[PATCH v1 0/7] The power allocator thermal governor

[PATCH v1 0/7] The power allocator thermal governor

[Javi Merino]

Hi linux-pm,

The power allocator governor allocates device power to control
temperature.  This requires transforming performance requests into
requested power, which we do with an extended cooling device API
introduced in patch 2 (thermal: extend the cooling device API to
include power information).  Patch 3 (thermal: cpu_cooling: implement
the power cooling device API) extends the cpu cooling device using a
simple power model.

This series depend on the array printing helper v5[0] and the weight
fixes[1].  Rui said that he had applied patch 1 (thermal: let
governors have private data for each thermal zone) but I can't see it
in his tree, so I'm reposting it.

[0] http://mid.gmane.org/1422449335-8289-1-git-send-email-javi.merino%40arm.com
[1] http://thread.gmane.org/gmane.linux.power-management.general/55730

Changes since RFC v6:
  - Addressed Eduardo's review
    + Pass the interval to the static power function as suggested by
      Eduardo
    + Make the cooling device ops return 0 or -E* and put the
      calculation in a parameter, like the rest of the cooling device
      ops
    + Documentation improvements
  - Use thermal_cdev_update() to change cooling device states
  - Add a patch to export the power allocator governor's tzp
    parameters to sysfs

Changes since RFC v5:
  - Addressed Stephen's review of the trace patches.
  - Removed power actors and extended the cooling device interface
    instead.
  - Let platforms override the power allocator governor parameters in
    their thermal zone parameters

Changes since RFC v4:
  - Add more tracing
  - Document some of the limitations of the power allocator governor
  - Export the power_actor API and move power_actor.h to include/linux

Changes since RFC v3:
  - Use tz->passive to poll faster when the first trip point is hit.
  - Don't make a special directory for power_actors
  - Add a DT property for sustainable-power
  - Simplify the static power interface and pass the current thermal
    zone in every power_actor_ops to remove the controversial
    enum power_actor_types
  - Use locks with the actor_list list
  - Use cpufreq_get() to get the frequency of the cpu instead of
    using the notifiers.
  - Remove the prompt for THERMAL_POWER_ACTOR_CPU when configuring
    the kernel

Changes since RFC v2:
  - Changed the PI controller into a PID controller
  - Added static power to the cpu power model
  - tz parameter max_dissipatable_power renamed to sustainable_power
  - Register the cpufreq cooling device as part of the
    power_cpu_actor registration.

Changes since RFC v1:
  - Fixed finding cpufreq cooling devices in cpufreq_frequency_change()
  - Replaced the cooling device interface with a separate power actor
    API
  - Addressed most of Eduardo's comments
  - Incorporated ftrace support for bitmask to trace cpumasks

Cheers,
Javi & Punit

Javi Merino (6):
  thermal: let governors have private data for each thermal zone
  thermal: extend the cooling device API to include power information
  thermal: cpu_cooling: implement the power cooling device API
  thermal: introduce the Power Allocator governor
  thermal: add trace events to the power allocator governor
  thermal: export thermal_zone_parameters to sysfs

Punit Agrawal (1):
  of: thermal: Introduce sustainable power for a thermal zone

 .../devicetree/bindings/thermal/thermal.txt        |   9 +
 Documentation/thermal/cpu-cooling-api.txt          | 156 ++++++-
 Documentation/thermal/power_allocator.txt          | 241 ++++++++++
 Documentation/thermal/sysfs-api.txt                |  52 +++
 drivers/thermal/Kconfig                            |  15 +
 drivers/thermal/Makefile                           |   1 +
 drivers/thermal/cpu_cooling.c                      | 507 ++++++++++++++++++++-
 drivers/thermal/of-thermal.c                       |   4 +
 drivers/thermal/power_allocator.c                  | 496 ++++++++++++++++++++
 drivers/thermal/thermal_core.c                     | 254 ++++++++++-
 drivers/thermal/thermal_core.h                     |   8 +
 include/linux/cpu_cooling.h                        |  39 ++
 include/linux/thermal.h                            |  64 ++-
 include/trace/events/thermal.h                     |  58 +++
 include/trace/events/thermal_power_allocator.h     |  80 ++++
 15 files changed, 1964 insertions(+), 20 deletions(-)
 create mode 100644 Documentation/thermal/power_allocator.txt
 create mode 100644 drivers/thermal/power_allocator.c
 create mode 100644 include/trace/events/thermal_power_allocator.h

-- 
1.9.1

[PATCH v1 1/7] thermal: let governors have private data for each thermal zone

[Javi Merino]

A governor may need to store its current state between calls to
throttle().  That state depends on the thermal zone, so store it as
private data in struct thermal_zone_device.

The governors may have two new ops: bind_to_tz() and unbind_from_tz().
When provided, these functions let governors do some initialization
and teardown when they are bound/unbound to a tz and possibly store that
information in the governor_data field of the struct
thermal_zone_device.

Cc: Zhang Rui <rui.zhang@intel.com>
Cc: Eduardo Valentin <edubezval@gmail.com>
Signed-off-by: Javi Merino <javi.merino@arm.com>
---

Hi Rui,

You said[0] that you had applied it but I can't see it in any of your trees, so I'm sending it again.

[0] http://thread.gmane.org/gmane.linux.kernel/1845418/focus=54163
---
 drivers/thermal/thermal_core.c | 83 ++++++++++++++++++++++++++++++++++++++----
 include/linux/thermal.h        |  9 +++++
 2 files changed, 84 insertions(+), 8 deletions(-)

diff --git a/drivers/thermal/thermal_core.c b/drivers/thermal/thermal_core.c
index 87e0b0782023..bf230c64e016 100644
--- a/drivers/thermal/thermal_core.c
+++ b/drivers/thermal/thermal_core.c
@@ -75,6 +75,58 @@ static struct thermal_governor *__find_governor(const char *name)
 	return NULL;
 }
 
+/**
+ * bind_previous_governor() - bind the previous governor of the thermal zone
+ * @tz:		a valid pointer to a struct thermal_zone_device
+ * @failed_gov_name:	the name of the governor that failed to register
+ *
+ * Register the previous governor of the thermal zone after a new
+ * governor has failed to be bound.
+ */
+static void bind_previous_governor(struct thermal_zone_device *tz,
+				   const char *failed_gov_name)
+{
+	if (tz->governor && tz->governor->bind_to_tz) {
+		if (tz->governor->bind_to_tz(tz)) {
+			dev_err(&tz->device,
+				"governor %s failed to bind and the previous one (%s) failed to bind again, thermal zone %s has no governor\n",
+				failed_gov_name, tz->governor->name, tz->type);
+			tz->governor = NULL;
+		}
+	}
+}
+
+/**
+ * thermal_set_governor() - Switch to another governor
+ * @tz:		a valid pointer to a struct thermal_zone_device
+ * @new_gov:	pointer to the new governor
+ *
+ * Change the governor of thermal zone @tz.
+ *
+ * Return: 0 on success, an error if the new governor's bind_to_tz() failed.
+ */
+static int thermal_set_governor(struct thermal_zone_device *tz,
+				struct thermal_governor *new_gov)
+{
+	int ret = 0;
+
+	if (tz->governor && tz->governor->unbind_from_tz)
+		tz->governor->unbind_from_tz(tz);
+
+	if (new_gov && new_gov->bind_to_tz) {
+		ret = new_gov->bind_to_tz(tz);
+		if (ret) {
+			bind_previous_governor(tz, new_gov->name);
+
+			return ret;
+		}
+	}
+
+	tz->governor = new_gov;
+
+	return ret;
+}
+
 int thermal_register_governor(struct thermal_governor *governor)
 {
 	int err;
@@ -107,8 +159,15 @@ int thermal_register_governor(struct thermal_governor *governor)
 
 		name = pos->tzp->governor_name;
 
-		if (!strncasecmp(name, governor->name, THERMAL_NAME_LENGTH))
-			pos->governor = governor;
+		if (!strncasecmp(name, governor->name, THERMAL_NAME_LENGTH)) {
+			int ret;
+
+			ret = thermal_set_governor(pos, governor);
+			if (ret)
+				dev_err(&pos->device,
+					"Failed to set governor %s for thermal zone %s: %d\n",
+					governor->name, pos->type, ret);
+		}
 	}
 
 	mutex_unlock(&thermal_list_lock);
@@ -134,7 +193,7 @@ void thermal_unregister_governor(struct thermal_governor *governor)
 	list_for_each_entry(pos, &thermal_tz_list, node) {
 		if (!strncasecmp(pos->governor->name, governor->name,
 						THERMAL_NAME_LENGTH))
-			pos->governor = NULL;
+			thermal_set_governor(pos, NULL);
 	}
 
 	mutex_unlock(&thermal_list_lock);
@@ -763,8 +822,9 @@ policy_store(struct device *dev, struct device_attribute *attr,
 	if (!gov)
 		goto exit;
 
-	tz->governor = gov;
-	ret = count;
+	ret = thermal_set_governor(tz, gov);
+	if (!ret)
+		ret = count;
 
 exit:
 	mutex_unlock(&tz->lock);
@@ -1463,6 +1523,7 @@ struct thermal_zone_device *thermal_zone_device_register(const char *type,
 	int result;
 	int count;
 	int passive = 0;
+	struct thermal_governor *governor;
 
 	if (type && strlen(type) >= THERMAL_NAME_LENGTH)
 		return ERR_PTR(-EINVAL);
@@ -1553,9 +1614,15 @@ struct thermal_zone_device *thermal_zone_device_register(const char *type,
 	mutex_lock(&thermal_governor_lock);
 
 	if (tz->tzp)
-		tz->governor = __find_governor(tz->tzp->governor_name);
+		governor = __find_governor(tz->tzp->governor_name);
 	else
-		tz->governor = def_governor;
+		governor = def_governor;
+
+	result = thermal_set_governor(tz, governor);
+	if (result) {
+		mutex_unlock(&thermal_governor_lock);
+		goto unregister;
+	}
 
 	mutex_unlock(&thermal_governor_lock);
 
@@ -1644,7 +1711,7 @@ void thermal_zone_device_unregister(struct thermal_zone_device *tz)
 		device_remove_file(&tz->device, &dev_attr_mode);
 	device_remove_file(&tz->device, &dev_attr_policy);
 	remove_trip_attrs(tz);
-	tz->governor = NULL;
+	thermal_set_governor(tz, NULL);
 
 	thermal_remove_hwmon_sysfs(tz);
 	release_idr(&thermal_tz_idr, &thermal_idr_lock, tz->id);
diff --git a/include/linux/thermal.h b/include/linux/thermal.h
index fc52e307efab..03dec86abc79 100644
--- a/include/linux/thermal.h
+++ b/include/linux/thermal.h
@@ -162,6 +162,7 @@ struct thermal_attr {
  * @ops:	operations this &thermal_zone_device supports
  * @tzp:	thermal zone parameters
  * @governor:	pointer to the governor for this thermal zone
+ * @governor_data:	private pointer for governor data
  * @thermal_instances:	list of &struct thermal_instance of this thermal zone
  * @idr:	&struct idr to generate unique id for this zone's cooling
  *		devices
@@ -188,6 +189,7 @@ struct thermal_zone_device {
 	struct thermal_zone_device_ops *ops;
 	const struct thermal_zone_params *tzp;
 	struct thermal_governor *governor;
+	void *governor_data;
 	struct list_head thermal_instances;
 	struct idr idr;
 	struct mutex lock;
@@ -198,12 +200,19 @@ struct thermal_zone_device {
 /**
  * struct thermal_governor - structure that holds thermal governor information
  * @name:	name of the governor
+ * @bind_to_tz: callback called when binding to a thermal zone.  If it
+ *		returns 0, the governor is bound to the thermal zone,
+ *		otherwise it fails.
+ * @unbind_from_tz:	callback called when a governor is unbound from a
+ *			thermal zone.
  * @throttle:	callback called for every trip point even if temperature is
  *		below the trip point temperature
  * @governor_list:	node in thermal_governor_list (in thermal_core.c)
  */
 struct thermal_governor {
 	char name[THERMAL_NAME_LENGTH];
+	int (*bind_to_tz)(struct thermal_zone_device *tz);
+	void (*unbind_from_tz)(struct thermal_zone_device *tz);
 	int (*throttle)(struct thermal_zone_device *tz, int trip);
 	struct list_head	governor_list;
 };
-- 
1.9.1

[PATCH v1 2/7] thermal: extend the cooling device API to include power information

[Javi Merino]

Add three optional callbacks to the cooling device interface to allow
them to express power.  In addition to the callbacks, add helpers to
identify cooling devices that implement the power cooling device API.

Cc: Zhang Rui <rui.zhang@intel.com>
Cc: Eduardo Valentin <edubezval@gmail.com>
Signed-off-by: Javi Merino <javi.merino@arm.com>
---
 drivers/thermal/thermal_core.c | 52 ++++++++++++++++++++++++++++++++++++++++++
 include/linux/thermal.h        | 18 +++++++++++++++
 2 files changed, 70 insertions(+)

diff --git a/drivers/thermal/thermal_core.c b/drivers/thermal/thermal_core.c
index bf230c64e016..a01d4a72bd93 100644
--- a/drivers/thermal/thermal_core.c
+++ b/drivers/thermal/thermal_core.c
@@ -868,6 +868,58 @@ emul_temp_store(struct device *dev, struct device_attribute *attr,
 static DEVICE_ATTR(emul_temp, S_IWUSR, NULL, emul_temp_store);
 #endif/*CONFIG_THERMAL_EMULATION*/
 
+/**
+ * power_actor_get_max_power() - get the maximum power that a cdev can consume
+ * @cdev:	pointer to &thermal_cooling_device
+ * @tz:		a valid thermal zone device pointer
+ * @max_power:	pointer in which to store the maximum power
+ *
+ * Calculate the maximum power consumption in milliwats that the
+ * cooling device can currently consume and store it in @max_power.
+ *
+ * Return: 0 on success, -EINVAL if @cdev doesn't support the
+ * power_actor API or -E* on other error.
+ */
+int power_actor_get_max_power(struct thermal_cooling_device *cdev,
+			      struct thermal_zone_device *tz, u32 *max_power)
+{
+	if (!cdev_is_power_actor(cdev))
+		return -EINVAL;
+
+	return cdev->ops->state2power(cdev, tz, 0, max_power);
+}
+
+/**
+ * power_actor_set_power() - limit the maximum power that a cooling device can consume
+ * @cdev:	pointer to &thermal_cooling_device
+ * @instance:	thermal instance to update
+ * @power:	the power in milliwatts
+ *
+ * Set the cooling device to consume at most @power milliwatts.
+ *
+ * Return: 0 on success, -EINVAL if the cooling device does not
+ * implement the power actor API or -E* for other failures.
+ */
+int power_actor_set_power(struct thermal_cooling_device *cdev,
+			  struct thermal_instance *instance, u32 power)
+{
+	unsigned long state;
+	int ret;
+
+	if (!cdev_is_power_actor(cdev))
+		return -EINVAL;
+
+	ret = cdev->ops->power2state(cdev, instance->tz, power, &state);
+	if (ret)
+		return ret;
+
+	instance->target = state;
+	cdev->updated = false;
+	thermal_cdev_update(cdev);
+
+	return 0;
+}
+
 static DEVICE_ATTR(type, 0444, type_show, NULL);
 static DEVICE_ATTR(temp, 0444, temp_show, NULL);
 static DEVICE_ATTR(mode, 0644, mode_show, mode_store);
diff --git a/include/linux/thermal.h b/include/linux/thermal.h
index 03dec86abc79..288ac6fd743d 100644
--- a/include/linux/thermal.h
+++ b/include/linux/thermal.h
@@ -60,6 +60,7 @@
 
 struct thermal_zone_device;
 struct thermal_cooling_device;
+struct thermal_instance;
 
 enum thermal_device_mode {
 	THERMAL_DEVICE_DISABLED = 0,
@@ -113,6 +114,12 @@ struct thermal_cooling_device_ops {
 	int (*get_max_state) (struct thermal_cooling_device *, unsigned long *);
 	int (*get_cur_state) (struct thermal_cooling_device *, unsigned long *);
 	int (*set_cur_state) (struct thermal_cooling_device *, unsigned long);
+	int (*get_requested_power)(struct thermal_cooling_device *,
+				   struct thermal_zone_device *, u32 *);
+	int (*state2power)(struct thermal_cooling_device *,
+			   struct thermal_zone_device *, unsigned long, u32 *);
+	int (*power2state)(struct thermal_cooling_device *,
+			   struct thermal_zone_device *, u32, unsigned long *);
 };
 
 struct thermal_cooling_device {
@@ -323,6 +330,17 @@ void thermal_zone_of_sensor_unregister(struct device *dev,
 }
 
 #endif
+
+static inline bool cdev_is_power_actor(struct thermal_cooling_device *cdev)
+{
+	return cdev->ops->get_requested_power && cdev->ops->state2power &&
+		cdev->ops->power2state;
+}
+
+int power_actor_get_max_power(struct thermal_cooling_device *,
+			      struct thermal_zone_device *tz, u32 *max_power);
+int power_actor_set_power(struct thermal_cooling_device *,
+			  struct thermal_instance *, u32);
 struct thermal_zone_device *thermal_zone_device_register(const char *, int, int,
 		void *, struct thermal_zone_device_ops *,
 		const struct thermal_zone_params *, int, int);
-- 
1.9.1

[PATCH v1 3/7] thermal: cpu_cooling: implement the power cooling device API

[Javi Merino]

Add a basic power model to the cpu cooling device to implement the
power cooling device API.  The power model uses the current frequency,
current load and OPPs for the power calculations.  The cpus must have
registered their OPPs using the OPP library.

Cc: Zhang Rui <rui.zhang@intel.com>
Cc: Eduardo Valentin <edubezval@gmail.com>
Signed-off-by: Punit Agrawal <punit.agrawal@arm.com>
Signed-off-by: Javi Merino <javi.merino@arm.com>
---
 Documentation/thermal/cpu-cooling-api.txt | 156 +++++++++-
 drivers/thermal/cpu_cooling.c             | 480 +++++++++++++++++++++++++++++-
 include/linux/cpu_cooling.h               |  39 +++
 3 files changed, 670 insertions(+), 5 deletions(-)

diff --git a/Documentation/thermal/cpu-cooling-api.txt b/Documentation/thermal/cpu-cooling-api.txt
index 753e47cc2e20..71653584cd03 100644
--- a/Documentation/thermal/cpu-cooling-api.txt
+++ b/Documentation/thermal/cpu-cooling-api.txt
@@ -36,8 +36,162 @@ the user. The registration APIs returns the cooling device pointer.
     np: pointer to the cooling device device tree node
     clip_cpus: cpumask of cpus where the frequency constraints will happen.
 
-1.1.3 void cpufreq_cooling_unregister(struct thermal_cooling_device *cdev)
+1.1.3 struct thermal_cooling_device *cpufreq_power_cooling_register(
+    const struct cpumask *clip_cpus, u32 capacitance,
+    get_static_t plat_static_func)
+
+Similar to cpufreq_cooling_register, this function registers a cpufreq
+cooling device.  Using this function, the cooling device will
+implement the power extensions by using a simple cpu power model.  The
+cpus must have registered their OPPs using the OPP library.
+
+The additional parameters are needed for the power model (See 2. Power
+models).  "capacitance" is the dynamic power coefficient (See 2.1
+Dynamic power).  "plat_static_func" is a function to calculate the
+static power consumed by these cpus (See 2.2 Static power).
+
+1.1.4 struct thermal_cooling_device *of_cpufreq_power_cooling_register(
+    struct device_node *np, const struct cpumask *clip_cpus, u32 capacitance,
+    get_static_t plat_static_func)
+
+Similar to cpufreq_power_cooling_register, this function register a
+cpufreq cooling device with power extensions using the device tree
+information supplied by the np parameter.
+
+1.1.5 void cpufreq_cooling_unregister(struct thermal_cooling_device *cdev)
 
     This interface function unregisters the "thermal-cpufreq-%x" cooling device.
 
     cdev: Cooling device pointer which has to be unregistered.
+
+2. Power models
+
+The power API registration functions provide a simple power model for
+CPUs.  The current power is calculated as dynamic + (optionally)
+static power.  This power model requires that the operating-points of
+the CPUs are registered using the kernel's opp library and the
+`cpufreq_frequency_table` is assigned to the `struct device` of the
+cpu.  If you are using CONFIG_CPUFREQ_DT then the
+`cpufreq_frequency_table` should already be assigned to the cpu
+device.
+
+The `plat_static_func` parameter of `cpufreq_power_cooling_register()`
+and `of_cpufreq_power_cooling_register()` is optional.  If you don't
+provide it, only dynamic power will be considered.
+
+2.1 Dynamic power
+
+The dynamic power consumption of a processor depends on many factors.
+For a given processor implementation the primary factors are:
+
+- The time the processor spends running, consuming dynamic power, as
+  compared to the time in idle states where dynamic consumption is
+  negligible.  Herein we refer to this as 'utilisation'.
+- The voltage and frequency levels as a result of DVFS.  The DVFS
+  level is a dominant factor governing power consumption.
+- In running time the 'execution' behaviour (instruction types, memory
+  access patterns and so forth) causes, in most cases, a second order
+  variation.  In pathological cases this variation can be significant,
+  but typically it is of a much lesser impact than the factors above.
+
+A high level dynamic power consumption model may then be represented as:
+
+Pdyn = f(run) * Voltage^2 * Frequency * Utilisation
+
+f(run) here represents the described execution behaviour and its
+result has a units of Watts/Hz/Volt^2 (this often expressed in
+mW/MHz/uVolt^2)
+
+The detailed behaviour for f(run) could be modelled on-line.  However,
+in practice, such an on-line model has dependencies on a number of
+implementation specific processor support and characterisation
+factors.  Therefore, in initial implementation that contribution is
+represented as a constant coefficient.  This is a simplification
+consistent with the relative contribution to overall power variation.
+
+In this simplified representation our model becomes:
+
+Pdyn = Capacitance * Voltage^2 * Frequency * Utilisation
+
+Where `capacitance` is a constant that represents an indicative
+running time dynamic power coefficient in fundamental units of
+mW/MHz/uVolt^2.  Typical values for mobile CPUs might lie in range
+from 100 to 500.  For reference, the approximate values for the SoC in
+ARM's Juno Development Platform are 530 for the Cortex-A57 cluster and
+140 for the Cortex-A53 cluster.
+
+
+2.2 Static power
+
+Static leakage power consumption depends on a number of factors.  For a
+given circuit implementation the primary factors are:
+
+- Time the circuit spends in each 'power state'
+- Temperature
+- Operating voltage
+- Process grade
+
+The time the circuit spends in each 'power state' for a given
+evaluation period at first order means OFF or ON.  However,
+'retention' states can also be supported that reduce power during
+inactive periods without loss of context.
+
+Note: The visibility of state entries to the OS can vary, according to
+platform specifics, and this can then impact the accuracy of a model
+based on OS state information alone.  It might be possible in some
+cases to extract more accurate information from system resources.
+
+The temperature, operating voltage and process 'grade' (slow to fast)
+of the circuit are all significant factors in static leakage power
+consumption.  All of these have complex relationships to static power.
+
+Circuit implementation specific factors include the chosen silicon
+process as well as the type, number and size of transistors in both
+the logic gates and any RAM elements included.
+
+The static power consumption modelling must take into account the
+power managed regions that are implemented.  Taking the example of an
+ARM processor cluster, the modelling would take into account whether
+each CPU can be powered OFF separately or if only a single power
+region is implemented for the complete cluster.
+
+In one view, there are others, a static power consumption model can
+then start from a set of reference values for each power managed
+region (e.g. CPU, Cluster/L2) in each state (e.g. ON, OFF) at an
+arbitrary process grade, voltage and temperature point.  These values
+are then scaled for all of the following: the time in each state, the
+process grade, the current temperature and the operating voltage.
+However, since both implementation specific and complex relationships
+dominate the estimate, the appropriate interface to the model from the
+cpu cooling device is to provide a function callback that calculates
+the static power in this platform.  When registering the cpu cooling
+device pass a function pointer that follows the `get_static_t`
+prototype:
+
+    int plat_get_static(cpumask_t *cpumask, int interval,
+                        unsigned long voltage, u32 &power);
+
+`cpumask` is the cpumask of the cpus involved in the calculation.
+`voltage` is the voltage at which they are operating.  The function
+should calculate the average static power for the last `interval`
+milliseconds.  It returns 0 on success, -E* on error.  If it
+succeeds, it should store the static power in `power`.  Reading the
+temperature of the cpus described by `cpumask` is left for
+plat_get_static() to do as the platform knows best which thermal
+sensor is closest to the cpu.
+
+If `plat_static_func` is NULL, static power is considered to be
+negligible for this platform and only dynamic power is considered.
+
+The platform specific callback can then use any combination of tables
+and/or equations to permute the estimated value.  Process grade
+information is not passed to the model since access to such data, from
+on-chip measurement capability or manufacture time data, is platform
+specific.
+
+Note: the significance of static power for CPUs in comparison to
+dynamic power is highly dependent on implementation.  Given the
+potential complexity in implementation, the importance and accuracy of
+its inclusion when using cpu cooling devices should be assessed on a
+case by case basis.
+
diff --git a/drivers/thermal/cpu_cooling.c b/drivers/thermal/cpu_cooling.c
index f65f0d109fc8..a639aaf228f5 100644
--- a/drivers/thermal/cpu_cooling.c
+++ b/drivers/thermal/cpu_cooling.c
@@ -26,6 +26,7 @@
 #include <linux/thermal.h>
 #include <linux/cpufreq.h>
 #include <linux/err.h>
+#include <linux/pm_opp.h>
 #include <linux/slab.h>
 #include <linux/cpu.h>
 #include <linux/cpu_cooling.h>
@@ -45,6 +46,19 @@
  */
 
 /**
+ * struct power_table - frequency to power conversion
+ * @frequency:	frequency in KHz
+ * @power:	power in mW
+ *
+ * This structure is built when the cooling device registers and helps
+ * in translating frequency to power and viceversa.
+ */
+struct power_table {
+	u32 frequency;
+	u32 power;
+};
+
+/**
  * struct cpufreq_cooling_device - data for cooling device with cpufreq
  * @id: unique integer value corresponding to each cpufreq_cooling_device
  *	registered.
@@ -58,6 +72,15 @@
  *	cpufreq frequencies.
  * @allowed_cpus: all the cpus involved for this cpufreq_cooling_device.
  * @node: list_head to link all cpufreq_cooling_device together.
+ * @last_load: load measured by the latest call to cpufreq_get_actual_power()
+ * @time_in_idle: previous reading of the absolute time that this cpu was idle
+ * @time_in_idle_timestamp: wall time of the last invocation of
+ *	get_cpu_idle_time_us()
+ * @dyn_power_table: array of struct power_table for frequency to power
+ *	conversion, sorted in ascending order.
+ * @dyn_power_table_entries: number of entries in the @dyn_power_table array
+ * @cpu_dev: the first cpu_device from @allowed_cpus that has OPPs registered
+ * @plat_get_static_power: callback to calculate the static power
  *
  * This structure is required for keeping information of each registered
  * cpufreq_cooling_device.
@@ -71,6 +94,13 @@ struct cpufreq_cooling_device {
 	unsigned int *freq_table;	/* In descending order */
 	struct cpumask allowed_cpus;
 	struct list_head node;
+	u32 last_load;
+	u64 time_in_idle[NR_CPUS];
+	u64 time_in_idle_timestamp[NR_CPUS];
+	struct power_table *dyn_power_table;
+	int dyn_power_table_entries;
+	struct device *cpu_dev;
+	get_static_t plat_get_static_power;
 };
 static DEFINE_IDR(cpufreq_idr);
 static DEFINE_MUTEX(cooling_cpufreq_lock);
@@ -205,6 +235,210 @@ static int cpufreq_thermal_notifier(struct notifier_block *nb,
 	return 0;
 }
 
+/**
+ * build_dyn_power_table() - create a dynamic power to frequency table
+ * @cpufreq_device:	the cpufreq cooling device in which to store the table
+ * @capacitance: dynamic power coefficient for these cpus
+ *
+ * Build a dynamic power to frequency table for this cpu and store it
+ * in @cpufreq_device.  This table will be used in cpu_power_to_freq() and
+ * cpu_freq_to_power() to convert between power and frequency
+ * efficiently.  Power is stored in mW, frequency in KHz.  The
+ * resulting table is in ascending order.
+ *
+ * Return: 0 on success, -E* on error.
+ */
+static int build_dyn_power_table(struct cpufreq_cooling_device *cpufreq_device,
+				 u32 capacitance)
+{
+	struct power_table *power_table;
+	struct dev_pm_opp *opp;
+	struct device *dev = NULL;
+	int num_opps = 0, cpu, i, ret = 0;
+	unsigned long freq;
+
+	rcu_read_lock();
+
+	for_each_cpu(cpu, &cpufreq_device->allowed_cpus) {
+		dev = get_cpu_device(cpu);
+		if (!dev) {
+			dev_warn(&cpufreq_device->cool_dev->device,
+				 "No cpu device for cpu %d\n", cpu);
+			continue;
+		}
+
+		num_opps = dev_pm_opp_get_opp_count(dev);
+		if (num_opps > 0) {
+			break;
+		} else if (num_opps < 0) {
+			ret = num_opps;
+			goto unlock;
+		}
+	}
+
+	if (num_opps == 0) {
+		ret = -EINVAL;
+		goto unlock;
+	}
+
+	power_table = kcalloc(num_opps, sizeof(*power_table), GFP_KERNEL);
+
+	for (freq = 0, i = 0;
+	     opp = dev_pm_opp_find_freq_ceil(dev, &freq), !IS_ERR(opp);
+	     freq++, i++) {
+		u32 freq_mhz, voltage_mv;
+		u64 power;
+
+		freq_mhz = freq / 1000000;
+		voltage_mv = dev_pm_opp_get_voltage(opp) / 1000;
+
+		/*
+		 * Do the multiplication with MHz and millivolt so as
+		 * to not overflow.
+		 */
+		power = (u64)capacitance * freq_mhz * voltage_mv * voltage_mv;
+		do_div(power, 1000000000);
+
+		/* frequency is stored in power_table in KHz */
+		power_table[i].frequency = freq / 1000;
+
+		/* power is stored in mW */
+		power_table[i].power = power;
+	}
+
+	if (i == 0) {
+		ret = PTR_ERR(opp);
+		goto unlock;
+	}
+
+	cpufreq_device->cpu_dev = dev;
+	cpufreq_device->dyn_power_table = power_table;
+	cpufreq_device->dyn_power_table_entries = i;
+
+unlock:
+	rcu_read_unlock();
+	return ret;
+}
+
+static u32 cpu_freq_to_power(struct cpufreq_cooling_device *cpufreq_device,
+			     u32 freq)
+{
+	int i;
+	struct power_table *pt = cpufreq_device->dyn_power_table;
+
+	for (i = 1; i < cpufreq_device->dyn_power_table_entries; i++)
+		if (freq < pt[i].frequency)
+			break;
+
+	return pt[i - 1].power;
+}
+
+static u32 cpu_power_to_freq(struct cpufreq_cooling_device *cpufreq_device,
+			     u32 power)
+{
+	int i;
+	struct power_table *pt = cpufreq_device->dyn_power_table;
+
+	for (i = 1; i < cpufreq_device->dyn_power_table_entries; i++)
+		if (power < pt[i].power)
+			break;
+
+	return pt[i - 1].frequency;
+}
+
+/**
+ * get_load() - get load for a cpu since last updated
+ * @cpufreq_device:	&struct cpufreq_cooling_device for this cpu
+ * @cpu:	cpu number
+ *
+ * Return: The average load of cpu @cpu in percentage since this
+ * function was last called.
+ */
+static u32 get_load(struct cpufreq_cooling_device *cpufreq_device, int cpu)
+{
+	u32 load;
+	u64 now, now_idle, delta_time, delta_idle;
+
+	now_idle = get_cpu_idle_time(cpu, &now, 0);
+	delta_idle = now_idle - cpufreq_device->time_in_idle[cpu];
+	delta_time = now - cpufreq_device->time_in_idle_timestamp[cpu];
+
+	if (delta_time <= delta_idle)
+		load = 0;
+	else
+		load = div64_u64(100 * (delta_time - delta_idle), delta_time);
+
+	cpufreq_device->time_in_idle[cpu] = now_idle;
+	cpufreq_device->time_in_idle_timestamp[cpu] = now;
+
+	return load;
+}
+
+/**
+ * get_static_power() - calculate the static power consumed by the cpus
+ * @cpufreq_device:	struct &cpufreq_cooling_device for this cpu cdev
+ * @tz:		thermal zone device in which we're operating
+ * @freq:	frequency in KHz
+ * @power:	pointer in which to store the calculated static power
+ *
+ * Calculate the static power consumed by the cpus described by
+ * @cpu_actor running at frequency @freq.  This function relies on a
+ * platform specific function that should have been provided when the
+ * actor was registered.  If it wasn't, the static power is assumed to
+ * be negligible.  The calculated static power is stored in @power.
+ *
+ * Return: 0 on success, -E* on failure.
+ */
+static int get_static_power(struct cpufreq_cooling_device *cpufreq_device,
+			    struct thermal_zone_device *tz, unsigned long freq,
+			    u32 *power)
+{
+	struct dev_pm_opp *opp;
+	unsigned long voltage;
+	struct cpumask *cpumask = &cpufreq_device->allowed_cpus;
+	unsigned long freq_hz = freq * 1000;
+
+	if (!cpufreq_device->plat_get_static_power) {
+		*power = 0;
+		return 0;
+	}
+
+	rcu_read_lock();
+
+	opp = dev_pm_opp_find_freq_exact(cpufreq_device->cpu_dev, freq_hz,
+					 true);
+	voltage = dev_pm_opp_get_voltage(opp);
+
+	rcu_read_unlock();
+
+	if (voltage == 0) {
+		dev_warn_ratelimited(cpufreq_device->cpu_dev,
+				     "Failed to get voltage for frequency %lu: %ld\n",
+				     freq_hz, IS_ERR(opp) ? PTR_ERR(opp) : 0);
+		return -EINVAL;
+	}
+
+	return cpufreq_device->plat_get_static_power(cpumask, tz->passive_delay,
+						     voltage, power);
+}
+
+/**
+ * get_dynamic_power() - calculate the dynamic power
+ * @cpufreq_device:	&cpufreq_cooling_device for this cdev
+ * @freq:	current frequency
+ *
+ * Return: the dynamic power consumed by the cpus described by
+ * @cpufreq_device.
+ */
+static u32 get_dynamic_power(struct cpufreq_cooling_device *cpufreq_device,
+			     unsigned long freq)
+{
+	u32 raw_cpu_power;
+
+	raw_cpu_power = cpu_freq_to_power(cpufreq_device, freq);
+	return (raw_cpu_power * cpufreq_device->last_load) / 100;
+}
+
 /* cpufreq cooling device callback functions are defined below */
 
 /**
@@ -280,8 +514,161 @@ static int cpufreq_set_cur_state(struct thermal_cooling_device *cdev,
 	return 0;
 }
 
+/**
+ * cpufreq_get_requested_power() - get the current power
+ * @cdev:	&thermal_cooling_device pointer
+ * @tz:		a valid thermal zone device pointer
+ * @power:	pointer in which to store the resulting power
+ *
+ * Calculate the current power consumption of the cpus in milliwatts
+ * and store it in @power.  This function should actually calculate
+ * the requested power, but it's hard to get the frequency that
+ * cpufreq would have assigned if there were no thermal limits.
+ * Instead, we calculate the current power on the assumption that the
+ * immediate future will look like the immediate past.
+ *
+ * Return: 0 on success, -E* if getting the static power failed.
+ */
+static int cpufreq_get_requested_power(struct thermal_cooling_device *cdev,
+				       struct thermal_zone_device *tz,
+				       u32 *power)
+{
+	unsigned long freq;
+	int cpu, ret;
+	u32 static_power, dynamic_power, total_load = 0;
+	struct cpufreq_cooling_device *cpufreq_device = cdev->devdata;
+
+	freq = cpufreq_quick_get(cpumask_any(&cpufreq_device->allowed_cpus));
+
+	for_each_cpu(cpu, &cpufreq_device->allowed_cpus) {
+		u32 load;
+
+		if (cpu_online(cpu))
+			load = get_load(cpufreq_device, cpu);
+		else
+			load = 0;
+
+		total_load += load;
+	}
+
+	cpufreq_device->last_load = total_load;
+
+	dynamic_power = get_dynamic_power(cpufreq_device, freq);
+	ret = get_static_power(cpufreq_device, tz, freq, &static_power);
+	if (ret)
+		return ret;
+
+	*power = static_power + dynamic_power;
+	return 0;
+}
+
+/**
+ * cpufreq_state2power() - convert a cpu cdev state to power consumed
+ * @cdev:	&thermal_cooling_device pointer
+ * @tz:		a valid thermal zone device pointer
+ * @state:	cooling device state to be converted
+ * @power:	pointer in which to store the resulting power
+ *
+ * Convert cooling device state @state into power consumption in
+ * milliwatts assuming 100% load.  Store the calculated power in
+ * @power.
+ *
+ * Return: 0 on success, -EINVAL if the cooling device state could not
+ * be converted into a frequency or other -E* if there was an error
+ * when calculating the static power.
+ */
+static int cpufreq_state2power(struct thermal_cooling_device *cdev,
+			       struct thermal_zone_device *tz,
+			       unsigned long state, u32 *power)
+{
+	unsigned int freq, num_cpus;
+	cpumask_t cpumask;
+	u32 static_power, dynamic_power;
+	int ret;
+	struct cpufreq_cooling_device *cpufreq_device = cdev->devdata;
+
+	cpumask_and(&cpumask, &cpufreq_device->allowed_cpus, cpu_online_mask);
+	num_cpus = cpumask_weight(&cpumask);
+
+	/* None of our cpus are online, so no power */
+	if (num_cpus == 0) {
+		*power = 0;
+		return 0;
+	}
+
+	freq = cpufreq_device->freq_table[state];
+	if (!freq)
+		return -EINVAL;
+
+	dynamic_power = cpu_freq_to_power(cpufreq_device, freq) * num_cpus;
+	ret = get_static_power(cpufreq_device, tz, freq, &static_power);
+	if (ret)
+		return ret;
+
+	*power = static_power + dynamic_power;
+	return 0;
+}
+
+/**
+ * cpufreq_power2state() - convert power to a cooling device state
+ * @cdev:	&thermal_cooling_device pointer
+ * @tz:		a valid thermal zone device pointer
+ * @power:	power in milliwatts to be converted
+ * @state:	pointer in which to store the resulting state
+ *
+ * Calculate a cooling device state for the cpus described by @cdev
+ * that would allow them to consume at most @power mW and store it in
+ * @state.  Note that this calculation depends on external factors
+ * such as the cpu load or the current static power.  Calling this
+ * function with the same power as input can yield different cooling
+ * device states depending on those external factors.
+ *
+ * Return: 0 on success, -ENODEV if no cpus are online or -EINVAL if
+ * the calculated frequency could not be converted to a valid state.
+ * The latter should not happen unless the frequencies available to
+ * cpufreq have changed since the initialization of the cpu cooling
+ * device.
+ */
+static int cpufreq_power2state(struct thermal_cooling_device *cdev,
+			       struct thermal_zone_device *tz, u32 power,
+			       unsigned long *state)
+{
+	unsigned int cpu, cur_freq, target_freq;
+	int ret;
+	s32 dyn_power;
+	u32 last_load, normalised_power, static_power;
+	struct cpufreq_cooling_device *cpufreq_device = cdev->devdata;
+
+	cpu = cpumask_any_and(&cpufreq_device->allowed_cpus, cpu_online_mask);
+
+	/* None of our cpus are online */
+	if (cpu >= nr_cpu_ids)
+		return -ENODEV;
+
+	cur_freq = cpufreq_quick_get(cpu);
+	ret = get_static_power(cpufreq_device, tz, cur_freq, &static_power);
+	if (ret)
+		return ret;
+
+	dyn_power = power - static_power;
+	dyn_power = dyn_power > 0 ? dyn_power : 0;
+	last_load = cpufreq_device->last_load ?: 1;
+	normalised_power = (dyn_power * 100) / last_load;
+	target_freq = cpu_power_to_freq(cpufreq_device, normalised_power);
+
+	*state = cpufreq_cooling_get_level(cpu, target_freq);
+	if (*state == THERMAL_CSTATE_INVALID) {
+		dev_warn_ratelimited(&cdev->device,
+				     "Failed to convert %dKHz for cpu %d into a cdev state\n",
+				     target_freq, cpu);
+		return -EINVAL;
+	}
+
+	return 0;
+}
+
 /* Bind cpufreq callbacks to thermal cooling device ops */
-static struct thermal_cooling_device_ops const cpufreq_cooling_ops = {
+static struct thermal_cooling_device_ops cpufreq_cooling_ops = {
 	.get_max_state = cpufreq_get_max_state,
 	.get_cur_state = cpufreq_get_cur_state,
 	.set_cur_state = cpufreq_set_cur_state,
@@ -311,6 +698,9 @@ static unsigned int find_next_max(struct cpufreq_frequency_table *table,
  * @np: a valid struct device_node to the cooling device device tree node
  * @clip_cpus: cpumask of cpus where the frequency constraints will happen.
  * Normally this should be same as cpufreq policy->related_cpus.
+ * @capacitance: dynamic power coefficient for these cpus
+ * @plat_static_func: function to calculate the static power consumed by these
+ *                    cpus (optional)
  *
  * This interface function registers the cpufreq cooling device with the name
  * "thermal-cpufreq-%x". This api can support multiple instances of cpufreq
@@ -322,7 +712,8 @@ static unsigned int find_next_max(struct cpufreq_frequency_table *table,
  */
 static struct thermal_cooling_device *
 __cpufreq_cooling_register(struct device_node *np,
-			   const struct cpumask *clip_cpus)
+			const struct cpumask *clip_cpus, u32 capacitance,
+			get_static_t plat_static_func)
 {
 	struct thermal_cooling_device *cool_dev;
 	struct cpufreq_cooling_device *cpufreq_dev;
@@ -357,6 +748,20 @@ __cpufreq_cooling_register(struct device_node *np,
 
 	cpumask_copy(&cpufreq_dev->allowed_cpus, clip_cpus);
 
+	if (capacitance) {
+		cpufreq_cooling_ops.get_requested_power =
+			cpufreq_get_requested_power;
+		cpufreq_cooling_ops.state2power = cpufreq_state2power;
+		cpufreq_cooling_ops.power2state = cpufreq_power2state;
+		cpufreq_dev->plat_get_static_power = plat_static_func;
+
+		ret = build_dyn_power_table(cpufreq_dev, capacitance);
+		if (ret) {
+			cool_dev = ERR_PTR(ret);
+			goto free_table;
+		}
+	}
+
 	ret = get_idr(&cpufreq_idr, &cpufreq_dev->id);
 	if (ret) {
 		cool_dev = ERR_PTR(ret);
@@ -422,7 +827,7 @@ free_cdev:
 struct thermal_cooling_device *
 cpufreq_cooling_register(const struct cpumask *clip_cpus)
 {
-	return __cpufreq_cooling_register(NULL, clip_cpus);
+	return __cpufreq_cooling_register(NULL, clip_cpus, 0, NULL);
 }
 EXPORT_SYMBOL_GPL(cpufreq_cooling_register);
 
@@ -446,11 +851,78 @@ of_cpufreq_cooling_register(struct device_node *np,
 	if (!np)
 		return ERR_PTR(-EINVAL);
 
-	return __cpufreq_cooling_register(np, clip_cpus);
+	return __cpufreq_cooling_register(np, clip_cpus, 0, NULL);
 }
 EXPORT_SYMBOL_GPL(of_cpufreq_cooling_register);
 
 /**
+ * cpufreq_power_cooling_register() - create cpufreq cooling device with power extensions
+ * @clip_cpus:	cpumask of cpus where the frequency constraints will happen
+ * @capacitance:	dynamic power coefficient for these cpus
+ * @plat_static_func:	function to calculate the static power consumed by these
+ *			cpus (optional)
+ *
+ * This interface function registers the cpufreq cooling device with
+ * the name "thermal-cpufreq-%x".  This api can support multiple
+ * instances of cpufreq cooling devices.  Using this function, the
+ * cooling device will implement the power extensions by using a
+ * simple cpu power model.  The cpus must have registered their OPPs
+ * using the OPP library.
+ *
+ * An optional @plat_static_func may be provided to calculate the
+ * static power consumed by these cpus.  If the platform's static
+ * power consumption is unknown or negligible, make it NULL.
+ *
+ * Return: a valid struct thermal_cooling_device pointer on success,
+ * on failure, it returns a corresponding ERR_PTR().
+ */
+struct thermal_cooling_device *
+cpufreq_power_cooling_register(const struct cpumask *clip_cpus, u32 capacitance,
+			       get_static_t plat_static_func)
+{
+	return __cpufreq_cooling_register(NULL, clip_cpus, capacitance,
+				plat_static_func);
+}
+EXPORT_SYMBOL(cpufreq_power_cooling_register);
+
+/**
+ * of_cpufreq_power_cooling_register() - create cpufreq cooling device with power extensions
+ * @np:	a valid struct device_node to the cooling device device tree node
+ * @clip_cpus:	cpumask of cpus where the frequency constraints will happen
+ * @capacitance:	dynamic power coefficient for these cpus
+ * @plat_static_func:	function to calculate the static power consumed by these
+ *			cpus (optional)
+ *
+ * This interface function registers the cpufreq cooling device with
+ * the name "thermal-cpufreq-%x".  This api can support multiple
+ * instances of cpufreq cooling devices.  Using this API, the cpufreq
+ * cooling device will be linked to the device tree node provided.
+ * Using this function, the cooling device will implement the power
+ * extensions by using a simple cpu power model.  The cpus must have
+ * registered their OPPs using the OPP library.
+ *
+ * An optional @plat_static_func may be provided to calculate the
+ * static power consumed by these cpus.  If the platform's static
+ * power consumption is unknown or negligible, make it NULL.
+ *
+ * Return: a valid struct thermal_cooling_device pointer on success,
+ * on failure, it returns a corresponding ERR_PTR().
+ */
+struct thermal_cooling_device *
+of_cpufreq_power_cooling_register(struct device_node *np,
+				  const struct cpumask *clip_cpus,
+				  u32 capacitance,
+				  get_static_t plat_static_func)
+{
+	if (!np)
+		return ERR_PTR(-EINVAL);
+
+	return __cpufreq_cooling_register(np, clip_cpus, capacitance,
+				plat_static_func);
+}
+EXPORT_SYMBOL(of_cpufreq_power_cooling_register);
+
+/**
  * cpufreq_cooling_unregister - function to remove cpufreq cooling device.
  * @cdev: thermal cooling device pointer.
  *
diff --git a/include/linux/cpu_cooling.h b/include/linux/cpu_cooling.h
index bd955270d5aa..c156f5082758 100644
--- a/include/linux/cpu_cooling.h
+++ b/include/linux/cpu_cooling.h
@@ -28,6 +28,9 @@
 #include <linux/thermal.h>
 #include <linux/cpumask.h>
 
+typedef int (*get_static_t)(cpumask_t *cpumask, int interval,
+			    unsigned long voltage, u32 *power);
+
 #ifdef CONFIG_CPU_THERMAL
 /**
  * cpufreq_cooling_register - function to create cpufreq cooling device.
@@ -36,6 +39,10 @@
 struct thermal_cooling_device *
 cpufreq_cooling_register(const struct cpumask *clip_cpus);
 
+struct thermal_cooling_device *
+cpufreq_power_cooling_register(const struct cpumask *clip_cpus,
+			       u32 capacitance, get_static_t plat_static_func);
+
 /**
  * of_cpufreq_cooling_register - create cpufreq cooling device based on DT.
  * @np: a valid struct device_node to the cooling device device tree node.
@@ -45,6 +52,12 @@ cpufreq_cooling_register(const struct cpumask *clip_cpus);
 struct thermal_cooling_device *
 of_cpufreq_cooling_register(struct device_node *np,
 			    const struct cpumask *clip_cpus);
+
+struct thermal_cooling_device *
+of_cpufreq_power_cooling_register(struct device_node *np,
+				  const struct cpumask *clip_cpus,
+				  u32 capacitance,
+				  get_static_t plat_static_func);
 #else
 static inline struct thermal_cooling_device *
 of_cpufreq_cooling_register(struct device_node *np,
@@ -52,6 +65,15 @@ of_cpufreq_cooling_register(struct device_node *np,
 {
 	return ERR_PTR(-ENOSYS);
 }
+
+static inline struct thermal_cooling_device *
+of_cpufreq_power_cooling_register(struct device_node *np,
+				  const struct cpumask *clip_cpus,
+				  u32 capacitance,
+				  get_static_t plat_static_func)
+{
+	return NULL;
+}
 #endif
 
 /**
@@ -68,11 +90,28 @@ cpufreq_cooling_register(const struct cpumask *clip_cpus)
 	return ERR_PTR(-ENOSYS);
 }
 static inline struct thermal_cooling_device *
+cpufreq_power_cooling_register(const struct cpumask *clip_cpus,
+			       u32 capacitance, get_static_t plat_static_func)
+{
+	return NULL;
+}
+
+static inline struct thermal_cooling_device *
 of_cpufreq_cooling_register(struct device_node *np,
 			    const struct cpumask *clip_cpus)
 {
 	return ERR_PTR(-ENOSYS);
 }
+
+static inline struct thermal_cooling_device *
+of_cpufreq_power_cooling_register(struct device_node *np,
+				  const struct cpumask *clip_cpus,
+				  u32 capacitance,
+				  get_static_t plat_static_func)
+{
+	return NULL;
+}
+
 static inline
 void cpufreq_cooling_unregister(struct thermal_cooling_device *cdev)
 {
-- 
1.9.1

Re: [PATCH v1 3/7] thermal: cpu_cooling: implement the power cooling device API

[Eduardo Valentin]

[-- Attachment #1: Type: text/plain, Size: 33059 bytes --]

On Wed, Jan 28, 2015 at 05:00:34PM +0000, Javi Merino wrote:
> Add a basic power model to the cpu cooling device to implement the
> power cooling device API.  The power model uses the current frequency,
> current load and OPPs for the power calculations.  The cpus must have
> registered their OPPs using the OPP library.
> 
> Cc: Zhang Rui <rui.zhang@intel.com>
> Cc: Eduardo Valentin <edubezval@gmail.com>
> Signed-off-by: Punit Agrawal <punit.agrawal@arm.com>
> Signed-off-by: Javi Merino <javi.merino@arm.com>
> ---
>  Documentation/thermal/cpu-cooling-api.txt | 156 +++++++++-
>  drivers/thermal/cpu_cooling.c             | 480 +++++++++++++++++++++++++++++-
>  include/linux/cpu_cooling.h               |  39 +++
>  3 files changed, 670 insertions(+), 5 deletions(-)
> 
> diff --git a/Documentation/thermal/cpu-cooling-api.txt b/Documentation/thermal/cpu-cooling-api.txt
> index 753e47cc2e20..71653584cd03 100644
> --- a/Documentation/thermal/cpu-cooling-api.txt
> +++ b/Documentation/thermal/cpu-cooling-api.txt
> @@ -36,8 +36,162 @@ the user. The registration APIs returns the cooling device pointer.
>      np: pointer to the cooling device device tree node
>      clip_cpus: cpumask of cpus where the frequency constraints will happen.
>  
> -1.1.3 void cpufreq_cooling_unregister(struct thermal_cooling_device *cdev)
> +1.1.3 struct thermal_cooling_device *cpufreq_power_cooling_register(
> +    const struct cpumask *clip_cpus, u32 capacitance,
> +    get_static_t plat_static_func)
> +
> +Similar to cpufreq_cooling_register, this function registers a cpufreq
> +cooling device.  Using this function, the cooling device will
> +implement the power extensions by using a simple cpu power model.  The
> +cpus must have registered their OPPs using the OPP library.
> +
> +The additional parameters are needed for the power model (See 2. Power
> +models).  "capacitance" is the dynamic power coefficient (See 2.1
> +Dynamic power).  "plat_static_func" is a function to calculate the
> +static power consumed by these cpus (See 2.2 Static power).
> +
> +1.1.4 struct thermal_cooling_device *of_cpufreq_power_cooling_register(
> +    struct device_node *np, const struct cpumask *clip_cpus, u32 capacitance,
> +    get_static_t plat_static_func)
> +
> +Similar to cpufreq_power_cooling_register, this function register a
> +cpufreq cooling device with power extensions using the device tree
> +information supplied by the np parameter.
> +
> +1.1.5 void cpufreq_cooling_unregister(struct thermal_cooling_device *cdev)
>  
>      This interface function unregisters the "thermal-cpufreq-%x" cooling device.
>  
>      cdev: Cooling device pointer which has to be unregistered.
> +
> +2. Power models
> +
> +The power API registration functions provide a simple power model for
> +CPUs.  The current power is calculated as dynamic + (optionally)
> +static power.  This power model requires that the operating-points of
> +the CPUs are registered using the kernel's opp library and the
> +`cpufreq_frequency_table` is assigned to the `struct device` of the
> +cpu.  If you are using CONFIG_CPUFREQ_DT then the
> +`cpufreq_frequency_table` should already be assigned to the cpu
> +device.
> +
> +The `plat_static_func` parameter of `cpufreq_power_cooling_register()`
> +and `of_cpufreq_power_cooling_register()` is optional.  If you don't
> +provide it, only dynamic power will be considered.
> +
> +2.1 Dynamic power
> +
> +The dynamic power consumption of a processor depends on many factors.
> +For a given processor implementation the primary factors are:
> +
> +- The time the processor spends running, consuming dynamic power, as
> +  compared to the time in idle states where dynamic consumption is
> +  negligible.  Herein we refer to this as 'utilisation'.
> +- The voltage and frequency levels as a result of DVFS.  The DVFS
> +  level is a dominant factor governing power consumption.
> +- In running time the 'execution' behaviour (instruction types, memory
> +  access patterns and so forth) causes, in most cases, a second order
> +  variation.  In pathological cases this variation can be significant,
> +  but typically it is of a much lesser impact than the factors above.
> +
> +A high level dynamic power consumption model may then be represented as:
> +
> +Pdyn = f(run) * Voltage^2 * Frequency * Utilisation
> +
> +f(run) here represents the described execution behaviour and its
> +result has a units of Watts/Hz/Volt^2 (this often expressed in
> +mW/MHz/uVolt^2)
> +
> +The detailed behaviour for f(run) could be modelled on-line.  However,
> +in practice, such an on-line model has dependencies on a number of
> +implementation specific processor support and characterisation
> +factors.  Therefore, in initial implementation that contribution is
> +represented as a constant coefficient.  This is a simplification
> +consistent with the relative contribution to overall power variation.
> +
> +In this simplified representation our model becomes:
> +
> +Pdyn = Capacitance * Voltage^2 * Frequency * Utilisation
> +
> +Where `capacitance` is a constant that represents an indicative
> +running time dynamic power coefficient in fundamental units of
> +mW/MHz/uVolt^2.  Typical values for mobile CPUs might lie in range
> +from 100 to 500.  For reference, the approximate values for the SoC in
> +ARM's Juno Development Platform are 530 for the Cortex-A57 cluster and
> +140 for the Cortex-A53 cluster.
> +
> +
> +2.2 Static power
> +
> +Static leakage power consumption depends on a number of factors.  For a
> +given circuit implementation the primary factors are:
> +
> +- Time the circuit spends in each 'power state'
> +- Temperature
> +- Operating voltage
> +- Process grade
> +
> +The time the circuit spends in each 'power state' for a given
> +evaluation period at first order means OFF or ON.  However,
> +'retention' states can also be supported that reduce power during
> +inactive periods without loss of context.
> +
> +Note: The visibility of state entries to the OS can vary, according to
> +platform specifics, and this can then impact the accuracy of a model
> +based on OS state information alone.  It might be possible in some
> +cases to extract more accurate information from system resources.
> +
> +The temperature, operating voltage and process 'grade' (slow to fast)
> +of the circuit are all significant factors in static leakage power
> +consumption.  All of these have complex relationships to static power.
> +
> +Circuit implementation specific factors include the chosen silicon
> +process as well as the type, number and size of transistors in both
> +the logic gates and any RAM elements included.
> +
> +The static power consumption modelling must take into account the
> +power managed regions that are implemented.  Taking the example of an
> +ARM processor cluster, the modelling would take into account whether
> +each CPU can be powered OFF separately or if only a single power
> +region is implemented for the complete cluster.
> +
> +In one view, there are others, a static power consumption model can
> +then start from a set of reference values for each power managed
> +region (e.g. CPU, Cluster/L2) in each state (e.g. ON, OFF) at an
> +arbitrary process grade, voltage and temperature point.  These values
> +are then scaled for all of the following: the time in each state, the
> +process grade, the current temperature and the operating voltage.
> +However, since both implementation specific and complex relationships
> +dominate the estimate, the appropriate interface to the model from the
> +cpu cooling device is to provide a function callback that calculates
> +the static power in this platform.  When registering the cpu cooling
> +device pass a function pointer that follows the `get_static_t`
> +prototype:
> +
> +    int plat_get_static(cpumask_t *cpumask, int interval,
> +                        unsigned long voltage, u32 &power);
> +
> +`cpumask` is the cpumask of the cpus involved in the calculation.
> +`voltage` is the voltage at which they are operating.  The function
> +should calculate the average static power for the last `interval`
> +milliseconds.  It returns 0 on success, -E* on error.  If it
> +succeeds, it should store the static power in `power`.  Reading the
> +temperature of the cpus described by `cpumask` is left for
> +plat_get_static() to do as the platform knows best which thermal
> +sensor is closest to the cpu.
> +
> +If `plat_static_func` is NULL, static power is considered to be
> +negligible for this platform and only dynamic power is considered.
> +
> +The platform specific callback can then use any combination of tables
> +and/or equations to permute the estimated value.  Process grade
> +information is not passed to the model since access to such data, from
> +on-chip measurement capability or manufacture time data, is platform
> +specific.
> +
> +Note: the significance of static power for CPUs in comparison to
> +dynamic power is highly dependent on implementation.  Given the
> +potential complexity in implementation, the importance and accuracy of
> +its inclusion when using cpu cooling devices should be assessed on a
> +case by case basis.
> +
> diff --git a/drivers/thermal/cpu_cooling.c b/drivers/thermal/cpu_cooling.c
> index f65f0d109fc8..a639aaf228f5 100644
> --- a/drivers/thermal/cpu_cooling.c
> +++ b/drivers/thermal/cpu_cooling.c
> @@ -26,6 +26,7 @@
>  #include <linux/thermal.h>
>  #include <linux/cpufreq.h>
>  #include <linux/err.h>
> +#include <linux/pm_opp.h>
>  #include <linux/slab.h>
>  #include <linux/cpu.h>
>  #include <linux/cpu_cooling.h>
> @@ -45,6 +46,19 @@
>   */
>  
>  /**
> + * struct power_table - frequency to power conversion
> + * @frequency:	frequency in KHz
> + * @power:	power in mW
> + *
> + * This structure is built when the cooling device registers and helps
> + * in translating frequency to power and viceversa.
> + */
> +struct power_table {
> +	u32 frequency;
> +	u32 power;
> +};
> +
> +/**
>   * struct cpufreq_cooling_device - data for cooling device with cpufreq
>   * @id: unique integer value corresponding to each cpufreq_cooling_device
>   *	registered.
> @@ -58,6 +72,15 @@
>   *	cpufreq frequencies.
>   * @allowed_cpus: all the cpus involved for this cpufreq_cooling_device.
>   * @node: list_head to link all cpufreq_cooling_device together.
> + * @last_load: load measured by the latest call to cpufreq_get_actual_power()
> + * @time_in_idle: previous reading of the absolute time that this cpu was idle
> + * @time_in_idle_timestamp: wall time of the last invocation of
> + *	get_cpu_idle_time_us()
> + * @dyn_power_table: array of struct power_table for frequency to power
> + *	conversion, sorted in ascending order.
> + * @dyn_power_table_entries: number of entries in the @dyn_power_table array
> + * @cpu_dev: the first cpu_device from @allowed_cpus that has OPPs registered
> + * @plat_get_static_power: callback to calculate the static power
>   *
>   * This structure is required for keeping information of each registered
>   * cpufreq_cooling_device.
> @@ -71,6 +94,13 @@ struct cpufreq_cooling_device {
>  	unsigned int *freq_table;	/* In descending order */
>  	struct cpumask allowed_cpus;
>  	struct list_head node;
> +	u32 last_load;
> +	u64 time_in_idle[NR_CPUS];
> +	u64 time_in_idle_timestamp[NR_CPUS];
> +	struct power_table *dyn_power_table;
> +	int dyn_power_table_entries;
> +	struct device *cpu_dev;
> +	get_static_t plat_get_static_power;
>  };
>  static DEFINE_IDR(cpufreq_idr);
>  static DEFINE_MUTEX(cooling_cpufreq_lock);
> @@ -205,6 +235,210 @@ static int cpufreq_thermal_notifier(struct notifier_block *nb,
>  	return 0;
>  }
>  
> +/**
> + * build_dyn_power_table() - create a dynamic power to frequency table
> + * @cpufreq_device:	the cpufreq cooling device in which to store the table
> + * @capacitance: dynamic power coefficient for these cpus
> + *
> + * Build a dynamic power to frequency table for this cpu and store it
> + * in @cpufreq_device.  This table will be used in cpu_power_to_freq() and
> + * cpu_freq_to_power() to convert between power and frequency
> + * efficiently.  Power is stored in mW, frequency in KHz.  The
> + * resulting table is in ascending order.
> + *
> + * Return: 0 on success, -E* on error.
> + */
> +static int build_dyn_power_table(struct cpufreq_cooling_device *cpufreq_device,
> +				 u32 capacitance)
> +{
> +	struct power_table *power_table;
> +	struct dev_pm_opp *opp;
> +	struct device *dev = NULL;
> +	int num_opps = 0, cpu, i, ret = 0;
> +	unsigned long freq;
> +
> +	rcu_read_lock();
> +
> +	for_each_cpu(cpu, &cpufreq_device->allowed_cpus) {
> +		dev = get_cpu_device(cpu);
> +		if (!dev) {
> +			dev_warn(&cpufreq_device->cool_dev->device,
> +				 "No cpu device for cpu %d\n", cpu);
> +			continue;
> +		}
> +
> +		num_opps = dev_pm_opp_get_opp_count(dev);
> +		if (num_opps > 0) {
> +			break;
> +		} else if (num_opps < 0) {
> +			ret = num_opps;
> +			goto unlock;
> +		}
> +	}
> +
> +	if (num_opps == 0) {
> +		ret = -EINVAL;
> +		goto unlock;
> +	}
> +
> +	power_table = kcalloc(num_opps, sizeof(*power_table), GFP_KERNEL);
> +
> +	for (freq = 0, i = 0;
> +	     opp = dev_pm_opp_find_freq_ceil(dev, &freq), !IS_ERR(opp);
> +	     freq++, i++) {
> +		u32 freq_mhz, voltage_mv;
> +		u64 power;
> +
> +		freq_mhz = freq / 1000000;
> +		voltage_mv = dev_pm_opp_get_voltage(opp) / 1000;
> +
> +		/*
> +		 * Do the multiplication with MHz and millivolt so as
> +		 * to not overflow.
> +		 */
> +		power = (u64)capacitance * freq_mhz * voltage_mv * voltage_mv;
> +		do_div(power, 1000000000);
> +
> +		/* frequency is stored in power_table in KHz */
> +		power_table[i].frequency = freq / 1000;
> +
> +		/* power is stored in mW */
> +		power_table[i].power = power;
> +	}
> +
> +	if (i == 0) {
> +		ret = PTR_ERR(opp);
> +		goto unlock;
> +	}
> +
> +	cpufreq_device->cpu_dev = dev;
> +	cpufreq_device->dyn_power_table = power_table;
> +	cpufreq_device->dyn_power_table_entries = i;
> +
> +unlock:
> +	rcu_read_unlock();
> +	return ret;
> +}
> +
> +static u32 cpu_freq_to_power(struct cpufreq_cooling_device *cpufreq_device,
> +			     u32 freq)
> +{
> +	int i;
> +	struct power_table *pt = cpufreq_device->dyn_power_table;
> +
> +	for (i = 1; i < cpufreq_device->dyn_power_table_entries; i++)
> +		if (freq < pt[i].frequency)
> +			break;
> +
> +	return pt[i - 1].power;
> +}
> +
> +static u32 cpu_power_to_freq(struct cpufreq_cooling_device *cpufreq_device,
> +			     u32 power)
> +{
> +	int i;
> +	struct power_table *pt = cpufreq_device->dyn_power_table;
> +
> +	for (i = 1; i < cpufreq_device->dyn_power_table_entries; i++)
> +		if (power < pt[i].power)
> +			break;
> +
> +	return pt[i - 1].frequency;
> +}
> +
> +/**
> + * get_load() - get load for a cpu since last updated
> + * @cpufreq_device:	&struct cpufreq_cooling_device for this cpu
> + * @cpu:	cpu number
> + *
> + * Return: The average load of cpu @cpu in percentage since this
> + * function was last called.
> + */
> +static u32 get_load(struct cpufreq_cooling_device *cpufreq_device, int cpu)
> +{
> +	u32 load;
> +	u64 now, now_idle, delta_time, delta_idle;
> +
> +	now_idle = get_cpu_idle_time(cpu, &now, 0);
> +	delta_idle = now_idle - cpufreq_device->time_in_idle[cpu];
> +	delta_time = now - cpufreq_device->time_in_idle_timestamp[cpu];
> +
> +	if (delta_time <= delta_idle)
> +		load = 0;
> +	else
> +		load = div64_u64(100 * (delta_time - delta_idle), delta_time);
> +
> +	cpufreq_device->time_in_idle[cpu] = now_idle;
> +	cpufreq_device->time_in_idle_timestamp[cpu] = now;
> +
> +	return load;
> +}
> +
> +/**
> + * get_static_power() - calculate the static power consumed by the cpus
> + * @cpufreq_device:	struct &cpufreq_cooling_device for this cpu cdev
> + * @tz:		thermal zone device in which we're operating
> + * @freq:	frequency in KHz
> + * @power:	pointer in which to store the calculated static power
> + *
> + * Calculate the static power consumed by the cpus described by
> + * @cpu_actor running at frequency @freq.  This function relies on a
> + * platform specific function that should have been provided when the
> + * actor was registered.  If it wasn't, the static power is assumed to
> + * be negligible.  The calculated static power is stored in @power.
> + *
> + * Return: 0 on success, -E* on failure.
> + */
> +static int get_static_power(struct cpufreq_cooling_device *cpufreq_device,
> +			    struct thermal_zone_device *tz, unsigned long freq,
> +			    u32 *power)
> +{
> +	struct dev_pm_opp *opp;
> +	unsigned long voltage;
> +	struct cpumask *cpumask = &cpufreq_device->allowed_cpus;
> +	unsigned long freq_hz = freq * 1000;
> +
> +	if (!cpufreq_device->plat_get_static_power) {
> +		*power = 0;
> +		return 0;
> +	}
> +
> +	rcu_read_lock();
> +
> +	opp = dev_pm_opp_find_freq_exact(cpufreq_device->cpu_dev, freq_hz,
> +					 true);
> +	voltage = dev_pm_opp_get_voltage(opp);
> +
> +	rcu_read_unlock();
> +
> +	if (voltage == 0) {
> +		dev_warn_ratelimited(cpufreq_device->cpu_dev,
> +				     "Failed to get voltage for frequency %lu: %ld\n",
> +				     freq_hz, IS_ERR(opp) ? PTR_ERR(opp) : 0);
> +		return -EINVAL;
> +	}
> +
> +	return cpufreq_device->plat_get_static_power(cpumask, tz->passive_delay,
> +						     voltage, power);
> +}
> +
> +/**
> + * get_dynamic_power() - calculate the dynamic power
> + * @cpufreq_device:	&cpufreq_cooling_device for this cdev
> + * @freq:	current frequency
> + *
> + * Return: the dynamic power consumed by the cpus described by
> + * @cpufreq_device.
> + */
> +static u32 get_dynamic_power(struct cpufreq_cooling_device *cpufreq_device,
> +			     unsigned long freq)
> +{
> +	u32 raw_cpu_power;
> +
> +	raw_cpu_power = cpu_freq_to_power(cpufreq_device, freq);
> +	return (raw_cpu_power * cpufreq_device->last_load) / 100;
> +}
> +
>  /* cpufreq cooling device callback functions are defined below */
>  
>  /**
> @@ -280,8 +514,161 @@ static int cpufreq_set_cur_state(struct thermal_cooling_device *cdev,
>  	return 0;
>  }
>  
> +/**
> + * cpufreq_get_requested_power() - get the current power
> + * @cdev:	&thermal_cooling_device pointer
> + * @tz:		a valid thermal zone device pointer
> + * @power:	pointer in which to store the resulting power
> + *
> + * Calculate the current power consumption of the cpus in milliwatts
> + * and store it in @power.  This function should actually calculate
> + * the requested power, but it's hard to get the frequency that
> + * cpufreq would have assigned if there were no thermal limits.
> + * Instead, we calculate the current power on the assumption that the
> + * immediate future will look like the immediate past.
> + *
> + * Return: 0 on success, -E* if getting the static power failed.
> + */
> +static int cpufreq_get_requested_power(struct thermal_cooling_device *cdev,
> +				       struct thermal_zone_device *tz,
> +				       u32 *power)
> +{
> +	unsigned long freq;
> +	int cpu, ret;
> +	u32 static_power, dynamic_power, total_load = 0;
> +	struct cpufreq_cooling_device *cpufreq_device = cdev->devdata;
> +
> +	freq = cpufreq_quick_get(cpumask_any(&cpufreq_device->allowed_cpus));
> +
> +	for_each_cpu(cpu, &cpufreq_device->allowed_cpus) {
> +		u32 load;
> +
> +		if (cpu_online(cpu))
> +			load = get_load(cpufreq_device, cpu);
> +		else
> +			load = 0;
> +
> +		total_load += load;
> +	}
> +
> +	cpufreq_device->last_load = total_load;
> +
> +	dynamic_power = get_dynamic_power(cpufreq_device, freq);
> +	ret = get_static_power(cpufreq_device, tz, freq, &static_power);
> +	if (ret)
> +		return ret;
> +
> +	*power = static_power + dynamic_power;
> +	return 0;
> +}

Repeating the query I've just made on v5, do we care if the system uses
different opps during the load sampling interval? 

Meaning, 1 - idle might not reflect the correct load.


> +
> +/**
> + * cpufreq_state2power() - convert a cpu cdev state to power consumed
> + * @cdev:	&thermal_cooling_device pointer
> + * @tz:		a valid thermal zone device pointer
> + * @state:	cooling device state to be converted
> + * @power:	pointer in which to store the resulting power
> + *
> + * Convert cooling device state @state into power consumption in
> + * milliwatts assuming 100% load.  Store the calculated power in
> + * @power.
> + *
> + * Return: 0 on success, -EINVAL if the cooling device state could not
> + * be converted into a frequency or other -E* if there was an error
> + * when calculating the static power.
> + */
> +static int cpufreq_state2power(struct thermal_cooling_device *cdev,
> +			       struct thermal_zone_device *tz,
> +			       unsigned long state, u32 *power)
> +{
> +	unsigned int freq, num_cpus;
> +	cpumask_t cpumask;
> +	u32 static_power, dynamic_power;
> +	int ret;
> +	struct cpufreq_cooling_device *cpufreq_device = cdev->devdata;
> +
> +	cpumask_and(&cpumask, &cpufreq_device->allowed_cpus, cpu_online_mask);
> +	num_cpus = cpumask_weight(&cpumask);
> +
> +	/* None of our cpus are online, so no power */
> +	if (num_cpus == 0) {
> +		*power = 0;
> +		return 0;
> +	}
> +
> +	freq = cpufreq_device->freq_table[state];
> +	if (!freq)
> +		return -EINVAL;
> +
> +	dynamic_power = cpu_freq_to_power(cpufreq_device, freq) * num_cpus;
> +	ret = get_static_power(cpufreq_device, tz, freq, &static_power);
> +	if (ret)
> +		return ret;
> +
> +	*power = static_power + dynamic_power;
> +	return 0;
> +}
> +
> +/**
> + * cpufreq_power2state() - convert power to a cooling device state
> + * @cdev:	&thermal_cooling_device pointer
> + * @tz:		a valid thermal zone device pointer
> + * @power:	power in milliwatts to be converted
> + * @state:	pointer in which to store the resulting state
> + *
> + * Calculate a cooling device state for the cpus described by @cdev
> + * that would allow them to consume at most @power mW and store it in
> + * @state.  Note that this calculation depends on external factors
> + * such as the cpu load or the current static power.  Calling this
> + * function with the same power as input can yield different cooling
> + * device states depending on those external factors.
> + *
> + * Return: 0 on success, -ENODEV if no cpus are online or -EINVAL if
> + * the calculated frequency could not be converted to a valid state.
> + * The latter should not happen unless the frequencies available to
> + * cpufreq have changed since the initialization of the cpu cooling
> + * device.
> + */
> +static int cpufreq_power2state(struct thermal_cooling_device *cdev,
> +			       struct thermal_zone_device *tz, u32 power,
> +			       unsigned long *state)
> +{
> +	unsigned int cpu, cur_freq, target_freq;
> +	int ret;
> +	s32 dyn_power;
> +	u32 last_load, normalised_power, static_power;
> +	struct cpufreq_cooling_device *cpufreq_device = cdev->devdata;
> +
> +	cpu = cpumask_any_and(&cpufreq_device->allowed_cpus, cpu_online_mask);
> +
> +	/* None of our cpus are online */
> +	if (cpu >= nr_cpu_ids)
> +		return -ENODEV;
> +
> +	cur_freq = cpufreq_quick_get(cpu);
> +	ret = get_static_power(cpufreq_device, tz, cur_freq, &static_power);
> +	if (ret)
> +		return ret;
> +
> +	dyn_power = power - static_power;
> +	dyn_power = dyn_power > 0 ? dyn_power : 0;
> +	last_load = cpufreq_device->last_load ?: 1;
> +	normalised_power = (dyn_power * 100) / last_load;
> +	target_freq = cpu_power_to_freq(cpufreq_device, normalised_power);
> +
> +	*state = cpufreq_cooling_get_level(cpu, target_freq);
> +	if (*state == THERMAL_CSTATE_INVALID) {
> +		dev_warn_ratelimited(&cdev->device,
> +				     "Failed to convert %dKHz for cpu %d into a cdev state\n",
> +				     target_freq, cpu);
> +		return -EINVAL;
> +	}
> +
> +	return 0;
> +}
> +
>  /* Bind cpufreq callbacks to thermal cooling device ops */
> -static struct thermal_cooling_device_ops const cpufreq_cooling_ops = {
> +static struct thermal_cooling_device_ops cpufreq_cooling_ops = {
>  	.get_max_state = cpufreq_get_max_state,
>  	.get_cur_state = cpufreq_get_cur_state,
>  	.set_cur_state = cpufreq_set_cur_state,
> @@ -311,6 +698,9 @@ static unsigned int find_next_max(struct cpufreq_frequency_table *table,
>   * @np: a valid struct device_node to the cooling device device tree node
>   * @clip_cpus: cpumask of cpus where the frequency constraints will happen.
>   * Normally this should be same as cpufreq policy->related_cpus.
> + * @capacitance: dynamic power coefficient for these cpus
> + * @plat_static_func: function to calculate the static power consumed by these
> + *                    cpus (optional)
>   *
>   * This interface function registers the cpufreq cooling device with the name
>   * "thermal-cpufreq-%x". This api can support multiple instances of cpufreq
> @@ -322,7 +712,8 @@ static unsigned int find_next_max(struct cpufreq_frequency_table *table,
>   */
>  static struct thermal_cooling_device *
>  __cpufreq_cooling_register(struct device_node *np,
> -			   const struct cpumask *clip_cpus)
> +			const struct cpumask *clip_cpus, u32 capacitance,
> +			get_static_t plat_static_func)
>  {
>  	struct thermal_cooling_device *cool_dev;
>  	struct cpufreq_cooling_device *cpufreq_dev;
> @@ -357,6 +748,20 @@ __cpufreq_cooling_register(struct device_node *np,
>  
>  	cpumask_copy(&cpufreq_dev->allowed_cpus, clip_cpus);
>  
> +	if (capacitance) {
> +		cpufreq_cooling_ops.get_requested_power =
> +			cpufreq_get_requested_power;
> +		cpufreq_cooling_ops.state2power = cpufreq_state2power;
> +		cpufreq_cooling_ops.power2state = cpufreq_power2state;
> +		cpufreq_dev->plat_get_static_power = plat_static_func;
> +
> +		ret = build_dyn_power_table(cpufreq_dev, capacitance);
> +		if (ret) {
> +			cool_dev = ERR_PTR(ret);
> +			goto free_table;
> +		}
> +	}
> +
>  	ret = get_idr(&cpufreq_idr, &cpufreq_dev->id);
>  	if (ret) {
>  		cool_dev = ERR_PTR(ret);
> @@ -422,7 +827,7 @@ free_cdev:
>  struct thermal_cooling_device *
>  cpufreq_cooling_register(const struct cpumask *clip_cpus)
>  {
> -	return __cpufreq_cooling_register(NULL, clip_cpus);
> +	return __cpufreq_cooling_register(NULL, clip_cpus, 0, NULL);
>  }
>  EXPORT_SYMBOL_GPL(cpufreq_cooling_register);
>  
> @@ -446,11 +851,78 @@ of_cpufreq_cooling_register(struct device_node *np,
>  	if (!np)
>  		return ERR_PTR(-EINVAL);
>  
> -	return __cpufreq_cooling_register(np, clip_cpus);
> +	return __cpufreq_cooling_register(np, clip_cpus, 0, NULL);
>  }
>  EXPORT_SYMBOL_GPL(of_cpufreq_cooling_register);
>  
>  /**
> + * cpufreq_power_cooling_register() - create cpufreq cooling device with power extensions
> + * @clip_cpus:	cpumask of cpus where the frequency constraints will happen
> + * @capacitance:	dynamic power coefficient for these cpus
> + * @plat_static_func:	function to calculate the static power consumed by these
> + *			cpus (optional)
> + *
> + * This interface function registers the cpufreq cooling device with
> + * the name "thermal-cpufreq-%x".  This api can support multiple
> + * instances of cpufreq cooling devices.  Using this function, the
> + * cooling device will implement the power extensions by using a
> + * simple cpu power model.  The cpus must have registered their OPPs
> + * using the OPP library.
> + *
> + * An optional @plat_static_func may be provided to calculate the
> + * static power consumed by these cpus.  If the platform's static
> + * power consumption is unknown or negligible, make it NULL.
> + *
> + * Return: a valid struct thermal_cooling_device pointer on success,
> + * on failure, it returns a corresponding ERR_PTR().
> + */
> +struct thermal_cooling_device *
> +cpufreq_power_cooling_register(const struct cpumask *clip_cpus, u32 capacitance,
> +			       get_static_t plat_static_func)
> +{
> +	return __cpufreq_cooling_register(NULL, clip_cpus, capacitance,
> +				plat_static_func);
> +}
> +EXPORT_SYMBOL(cpufreq_power_cooling_register);
> +
> +/**
> + * of_cpufreq_power_cooling_register() - create cpufreq cooling device with power extensions
> + * @np:	a valid struct device_node to the cooling device device tree node
> + * @clip_cpus:	cpumask of cpus where the frequency constraints will happen
> + * @capacitance:	dynamic power coefficient for these cpus
> + * @plat_static_func:	function to calculate the static power consumed by these
> + *			cpus (optional)
> + *
> + * This interface function registers the cpufreq cooling device with
> + * the name "thermal-cpufreq-%x".  This api can support multiple
> + * instances of cpufreq cooling devices.  Using this API, the cpufreq
> + * cooling device will be linked to the device tree node provided.
> + * Using this function, the cooling device will implement the power
> + * extensions by using a simple cpu power model.  The cpus must have
> + * registered their OPPs using the OPP library.
> + *
> + * An optional @plat_static_func may be provided to calculate the
> + * static power consumed by these cpus.  If the platform's static
> + * power consumption is unknown or negligible, make it NULL.
> + *
> + * Return: a valid struct thermal_cooling_device pointer on success,
> + * on failure, it returns a corresponding ERR_PTR().
> + */
> +struct thermal_cooling_device *
> +of_cpufreq_power_cooling_register(struct device_node *np,
> +				  const struct cpumask *clip_cpus,
> +				  u32 capacitance,
> +				  get_static_t plat_static_func)
> +{
> +	if (!np)
> +		return ERR_PTR(-EINVAL);
> +
> +	return __cpufreq_cooling_register(np, clip_cpus, capacitance,
> +				plat_static_func);
> +}
> +EXPORT_SYMBOL(of_cpufreq_power_cooling_register);
> +
> +/**
>   * cpufreq_cooling_unregister - function to remove cpufreq cooling device.
>   * @cdev: thermal cooling device pointer.
>   *
> diff --git a/include/linux/cpu_cooling.h b/include/linux/cpu_cooling.h
> index bd955270d5aa..c156f5082758 100644
> --- a/include/linux/cpu_cooling.h
> +++ b/include/linux/cpu_cooling.h
> @@ -28,6 +28,9 @@
>  #include <linux/thermal.h>
>  #include <linux/cpumask.h>
>  
> +typedef int (*get_static_t)(cpumask_t *cpumask, int interval,
> +			    unsigned long voltage, u32 *power);
> +
>  #ifdef CONFIG_CPU_THERMAL
>  /**
>   * cpufreq_cooling_register - function to create cpufreq cooling device.
> @@ -36,6 +39,10 @@
>  struct thermal_cooling_device *
>  cpufreq_cooling_register(const struct cpumask *clip_cpus);
>  
> +struct thermal_cooling_device *
> +cpufreq_power_cooling_register(const struct cpumask *clip_cpus,
> +			       u32 capacitance, get_static_t plat_static_func);
> +
>  /**
>   * of_cpufreq_cooling_register - create cpufreq cooling device based on DT.
>   * @np: a valid struct device_node to the cooling device device tree node.
> @@ -45,6 +52,12 @@ cpufreq_cooling_register(const struct cpumask *clip_cpus);
>  struct thermal_cooling_device *
>  of_cpufreq_cooling_register(struct device_node *np,
>  			    const struct cpumask *clip_cpus);
> +
> +struct thermal_cooling_device *
> +of_cpufreq_power_cooling_register(struct device_node *np,
> +				  const struct cpumask *clip_cpus,
> +				  u32 capacitance,
> +				  get_static_t plat_static_func);
>  #else
>  static inline struct thermal_cooling_device *
>  of_cpufreq_cooling_register(struct device_node *np,
> @@ -52,6 +65,15 @@ of_cpufreq_cooling_register(struct device_node *np,
>  {
>  	return ERR_PTR(-ENOSYS);
>  }
> +
> +static inline struct thermal_cooling_device *
> +of_cpufreq_power_cooling_register(struct device_node *np,
> +				  const struct cpumask *clip_cpus,
> +				  u32 capacitance,
> +				  get_static_t plat_static_func)
> +{
> +	return NULL;
> +}
>  #endif
>  
>  /**
> @@ -68,11 +90,28 @@ cpufreq_cooling_register(const struct cpumask *clip_cpus)
>  	return ERR_PTR(-ENOSYS);
>  }
>  static inline struct thermal_cooling_device *
> +cpufreq_power_cooling_register(const struct cpumask *clip_cpus,
> +			       u32 capacitance, get_static_t plat_static_func)
> +{
> +	return NULL;
> +}
> +
> +static inline struct thermal_cooling_device *
>  of_cpufreq_cooling_register(struct device_node *np,
>  			    const struct cpumask *clip_cpus)
>  {
>  	return ERR_PTR(-ENOSYS);
>  }
> +
> +static inline struct thermal_cooling_device *
> +of_cpufreq_power_cooling_register(struct device_node *np,
> +				  const struct cpumask *clip_cpus,
> +				  u32 capacitance,
> +				  get_static_t plat_static_func)
> +{
> +	return NULL;
> +}
> +
>  static inline
>  void cpufreq_cooling_unregister(struct thermal_cooling_device *cdev)
>  {
> -- 
> 1.9.1
> 

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Re: [PATCH v1 3/7] thermal: cpu_cooling: implement the power cooling device API

[Javi Merino]

On Wed, Jan 28, 2015 at 05:56:08PM +0000, Eduardo Valentin wrote:
> On Wed, Jan 28, 2015 at 05:00:34PM +0000, Javi Merino wrote:
> > Add a basic power model to the cpu cooling device to implement the
> > power cooling device API.  The power model uses the current frequency,
> > current load and OPPs for the power calculations.  The cpus must have
> > registered their OPPs using the OPP library.
> > 
> > Cc: Zhang Rui <rui.zhang@intel.com>
> > Cc: Eduardo Valentin <edubezval@gmail.com>
> > Signed-off-by: Punit Agrawal <punit.agrawal@arm.com>
> > Signed-off-by: Javi Merino <javi.merino@arm.com>
> > ---
> >  Documentation/thermal/cpu-cooling-api.txt | 156 +++++++++-
> >  drivers/thermal/cpu_cooling.c             | 480 +++++++++++++++++++++++++++++-
> >  include/linux/cpu_cooling.h               |  39 +++
> >  3 files changed, 670 insertions(+), 5 deletions(-)
> > 
> > diff --git a/Documentation/thermal/cpu-cooling-api.txt b/Documentation/thermal/cpu-cooling-api.txt
> > index 753e47cc2e20..71653584cd03 100644
> > --- a/Documentation/thermal/cpu-cooling-api.txt
> > +++ b/Documentation/thermal/cpu-cooling-api.txt
> > @@ -36,8 +36,162 @@ the user. The registration APIs returns the cooling device pointer.
> >      np: pointer to the cooling device device tree node
> >      clip_cpus: cpumask of cpus where the frequency constraints will happen.
> >  
> > -1.1.3 void cpufreq_cooling_unregister(struct thermal_cooling_device *cdev)
> > +1.1.3 struct thermal_cooling_device *cpufreq_power_cooling_register(
> > +    const struct cpumask *clip_cpus, u32 capacitance,
> > +    get_static_t plat_static_func)
> > +
> > +Similar to cpufreq_cooling_register, this function registers a cpufreq
> > +cooling device.  Using this function, the cooling device will
> > +implement the power extensions by using a simple cpu power model.  The
> > +cpus must have registered their OPPs using the OPP library.
> > +
> > +The additional parameters are needed for the power model (See 2. Power
> > +models).  "capacitance" is the dynamic power coefficient (See 2.1
> > +Dynamic power).  "plat_static_func" is a function to calculate the
> > +static power consumed by these cpus (See 2.2 Static power).
> > +
> > +1.1.4 struct thermal_cooling_device *of_cpufreq_power_cooling_register(
> > +    struct device_node *np, const struct cpumask *clip_cpus, u32 capacitance,
> > +    get_static_t plat_static_func)
> > +
> > +Similar to cpufreq_power_cooling_register, this function register a
> > +cpufreq cooling device with power extensions using the device tree
> > +information supplied by the np parameter.
> > +
> > +1.1.5 void cpufreq_cooling_unregister(struct thermal_cooling_device *cdev)
> >  
> >      This interface function unregisters the "thermal-cpufreq-%x" cooling device.
> >  
> >      cdev: Cooling device pointer which has to be unregistered.
> > +
> > +2. Power models
> > +
> > +The power API registration functions provide a simple power model for
> > +CPUs.  The current power is calculated as dynamic + (optionally)
> > +static power.  This power model requires that the operating-points of
> > +the CPUs are registered using the kernel's opp library and the
> > +`cpufreq_frequency_table` is assigned to the `struct device` of the
> > +cpu.  If you are using CONFIG_CPUFREQ_DT then the
> > +`cpufreq_frequency_table` should already be assigned to the cpu
> > +device.
> > +
> > +The `plat_static_func` parameter of `cpufreq_power_cooling_register()`
> > +and `of_cpufreq_power_cooling_register()` is optional.  If you don't
> > +provide it, only dynamic power will be considered.
> > +
> > +2.1 Dynamic power
> > +
> > +The dynamic power consumption of a processor depends on many factors.
> > +For a given processor implementation the primary factors are:
> > +
> > +- The time the processor spends running, consuming dynamic power, as
> > +  compared to the time in idle states where dynamic consumption is
> > +  negligible.  Herein we refer to this as 'utilisation'.
> > +- The voltage and frequency levels as a result of DVFS.  The DVFS
> > +  level is a dominant factor governing power consumption.
> > +- In running time the 'execution' behaviour (instruction types, memory
> > +  access patterns and so forth) causes, in most cases, a second order
> > +  variation.  In pathological cases this variation can be significant,
> > +  but typically it is of a much lesser impact than the factors above.
> > +
> > +A high level dynamic power consumption model may then be represented as:
> > +
> > +Pdyn = f(run) * Voltage^2 * Frequency * Utilisation
> > +
> > +f(run) here represents the described execution behaviour and its
> > +result has a units of Watts/Hz/Volt^2 (this often expressed in
> > +mW/MHz/uVolt^2)
> > +
> > +The detailed behaviour for f(run) could be modelled on-line.  However,
> > +in practice, such an on-line model has dependencies on a number of
> > +implementation specific processor support and characterisation
> > +factors.  Therefore, in initial implementation that contribution is
> > +represented as a constant coefficient.  This is a simplification
> > +consistent with the relative contribution to overall power variation.
> > +
> > +In this simplified representation our model becomes:
> > +
> > +Pdyn = Capacitance * Voltage^2 * Frequency * Utilisation
> > +
> > +Where `capacitance` is a constant that represents an indicative
> > +running time dynamic power coefficient in fundamental units of
> > +mW/MHz/uVolt^2.  Typical values for mobile CPUs might lie in range
> > +from 100 to 500.  For reference, the approximate values for the SoC in
> > +ARM's Juno Development Platform are 530 for the Cortex-A57 cluster and
> > +140 for the Cortex-A53 cluster.
> > +
> > +
> > +2.2 Static power
> > +
> > +Static leakage power consumption depends on a number of factors.  For a
> > +given circuit implementation the primary factors are:
> > +
> > +- Time the circuit spends in each 'power state'
> > +- Temperature
> > +- Operating voltage
> > +- Process grade
> > +
> > +The time the circuit spends in each 'power state' for a given
> > +evaluation period at first order means OFF or ON.  However,
> > +'retention' states can also be supported that reduce power during
> > +inactive periods without loss of context.
> > +
> > +Note: The visibility of state entries to the OS can vary, according to
> > +platform specifics, and this can then impact the accuracy of a model
> > +based on OS state information alone.  It might be possible in some
> > +cases to extract more accurate information from system resources.
> > +
> > +The temperature, operating voltage and process 'grade' (slow to fast)
> > +of the circuit are all significant factors in static leakage power
> > +consumption.  All of these have complex relationships to static power.
> > +
> > +Circuit implementation specific factors include the chosen silicon
> > +process as well as the type, number and size of transistors in both
> > +the logic gates and any RAM elements included.
> > +
> > +The static power consumption modelling must take into account the
> > +power managed regions that are implemented.  Taking the example of an
> > +ARM processor cluster, the modelling would take into account whether
> > +each CPU can be powered OFF separately or if only a single power
> > +region is implemented for the complete cluster.
> > +
> > +In one view, there are others, a static power consumption model can
> > +then start from a set of reference values for each power managed
> > +region (e.g. CPU, Cluster/L2) in each state (e.g. ON, OFF) at an
> > +arbitrary process grade, voltage and temperature point.  These values
> > +are then scaled for all of the following: the time in each state, the
> > +process grade, the current temperature and the operating voltage.
> > +However, since both implementation specific and complex relationships
> > +dominate the estimate, the appropriate interface to the model from the
> > +cpu cooling device is to provide a function callback that calculates
> > +the static power in this platform.  When registering the cpu cooling
> > +device pass a function pointer that follows the `get_static_t`
> > +prototype:
> > +
> > +    int plat_get_static(cpumask_t *cpumask, int interval,
> > +                        unsigned long voltage, u32 &power);
> > +
> > +`cpumask` is the cpumask of the cpus involved in the calculation.
> > +`voltage` is the voltage at which they are operating.  The function
> > +should calculate the average static power for the last `interval`
> > +milliseconds.  It returns 0 on success, -E* on error.  If it
> > +succeeds, it should store the static power in `power`.  Reading the
> > +temperature of the cpus described by `cpumask` is left for
> > +plat_get_static() to do as the platform knows best which thermal
> > +sensor is closest to the cpu.
> > +
> > +If `plat_static_func` is NULL, static power is considered to be
> > +negligible for this platform and only dynamic power is considered.
> > +
> > +The platform specific callback can then use any combination of tables
> > +and/or equations to permute the estimated value.  Process grade
> > +information is not passed to the model since access to such data, from
> > +on-chip measurement capability or manufacture time data, is platform
> > +specific.
> > +
> > +Note: the significance of static power for CPUs in comparison to
> > +dynamic power is highly dependent on implementation.  Given the
> > +potential complexity in implementation, the importance and accuracy of
> > +its inclusion when using cpu cooling devices should be assessed on a
> > +case by case basis.
> > +
> > diff --git a/drivers/thermal/cpu_cooling.c b/drivers/thermal/cpu_cooling.c
> > index f65f0d109fc8..a639aaf228f5 100644
> > --- a/drivers/thermal/cpu_cooling.c
> > +++ b/drivers/thermal/cpu_cooling.c
> > @@ -26,6 +26,7 @@
> >  #include <linux/thermal.h>
> >  #include <linux/cpufreq.h>
> >  #include <linux/err.h>
> > +#include <linux/pm_opp.h>
> >  #include <linux/slab.h>
> >  #include <linux/cpu.h>
> >  #include <linux/cpu_cooling.h>
> > @@ -45,6 +46,19 @@
> >   */
> >  
> >  /**
> > + * struct power_table - frequency to power conversion
> > + * @frequency:	frequency in KHz
> > + * @power:	power in mW
> > + *
> > + * This structure is built when the cooling device registers and helps
> > + * in translating frequency to power and viceversa.
> > + */
> > +struct power_table {
> > +	u32 frequency;
> > +	u32 power;
> > +};
> > +
> > +/**
> >   * struct cpufreq_cooling_device - data for cooling device with cpufreq
> >   * @id: unique integer value corresponding to each cpufreq_cooling_device
> >   *	registered.
> > @@ -58,6 +72,15 @@
> >   *	cpufreq frequencies.
> >   * @allowed_cpus: all the cpus involved for this cpufreq_cooling_device.
> >   * @node: list_head to link all cpufreq_cooling_device together.
> > + * @last_load: load measured by the latest call to cpufreq_get_actual_power()
> > + * @time_in_idle: previous reading of the absolute time that this cpu was idle
> > + * @time_in_idle_timestamp: wall time of the last invocation of
> > + *	get_cpu_idle_time_us()
> > + * @dyn_power_table: array of struct power_table for frequency to power
> > + *	conversion, sorted in ascending order.
> > + * @dyn_power_table_entries: number of entries in the @dyn_power_table array
> > + * @cpu_dev: the first cpu_device from @allowed_cpus that has OPPs registered
> > + * @plat_get_static_power: callback to calculate the static power
> >   *
> >   * This structure is required for keeping information of each registered
> >   * cpufreq_cooling_device.
> > @@ -71,6 +94,13 @@ struct cpufreq_cooling_device {
> >  	unsigned int *freq_table;	/* In descending order */
> >  	struct cpumask allowed_cpus;
> >  	struct list_head node;
> > +	u32 last_load;
> > +	u64 time_in_idle[NR_CPUS];
> > +	u64 time_in_idle_timestamp[NR_CPUS];
> > +	struct power_table *dyn_power_table;
> > +	int dyn_power_table_entries;
> > +	struct device *cpu_dev;
> > +	get_static_t plat_get_static_power;
> >  };
> >  static DEFINE_IDR(cpufreq_idr);
> >  static DEFINE_MUTEX(cooling_cpufreq_lock);
> > @@ -205,6 +235,210 @@ static int cpufreq_thermal_notifier(struct notifier_block *nb,
> >  	return 0;
> >  }
> >  
> > +/**
> > + * build_dyn_power_table() - create a dynamic power to frequency table
> > + * @cpufreq_device:	the cpufreq cooling device in which to store the table
> > + * @capacitance: dynamic power coefficient for these cpus
> > + *
> > + * Build a dynamic power to frequency table for this cpu and store it
> > + * in @cpufreq_device.  This table will be used in cpu_power_to_freq() and
> > + * cpu_freq_to_power() to convert between power and frequency
> > + * efficiently.  Power is stored in mW, frequency in KHz.  The
> > + * resulting table is in ascending order.
> > + *
> > + * Return: 0 on success, -E* on error.
> > + */
> > +static int build_dyn_power_table(struct cpufreq_cooling_device *cpufreq_device,
> > +				 u32 capacitance)
> > +{
> > +	struct power_table *power_table;
> > +	struct dev_pm_opp *opp;
> > +	struct device *dev = NULL;
> > +	int num_opps = 0, cpu, i, ret = 0;
> > +	unsigned long freq;
> > +
> > +	rcu_read_lock();
> > +
> > +	for_each_cpu(cpu, &cpufreq_device->allowed_cpus) {
> > +		dev = get_cpu_device(cpu);
> > +		if (!dev) {
> > +			dev_warn(&cpufreq_device->cool_dev->device,
> > +				 "No cpu device for cpu %d\n", cpu);
> > +			continue;
> > +		}
> > +
> > +		num_opps = dev_pm_opp_get_opp_count(dev);
> > +		if (num_opps > 0) {
> > +			break;
> > +		} else if (num_opps < 0) {
> > +			ret = num_opps;
> > +			goto unlock;
> > +		}
> > +	}
> > +
> > +	if (num_opps == 0) {
> > +		ret = -EINVAL;
> > +		goto unlock;
> > +	}
> > +
> > +	power_table = kcalloc(num_opps, sizeof(*power_table), GFP_KERNEL);
> > +
> > +	for (freq = 0, i = 0;
> > +	     opp = dev_pm_opp_find_freq_ceil(dev, &freq), !IS_ERR(opp);
> > +	     freq++, i++) {
> > +		u32 freq_mhz, voltage_mv;
> > +		u64 power;
> > +
> > +		freq_mhz = freq / 1000000;
> > +		voltage_mv = dev_pm_opp_get_voltage(opp) / 1000;
> > +
> > +		/*
> > +		 * Do the multiplication with MHz and millivolt so as
> > +		 * to not overflow.
> > +		 */
> > +		power = (u64)capacitance * freq_mhz * voltage_mv * voltage_mv;
> > +		do_div(power, 1000000000);
> > +
> > +		/* frequency is stored in power_table in KHz */
> > +		power_table[i].frequency = freq / 1000;
> > +
> > +		/* power is stored in mW */
> > +		power_table[i].power = power;
> > +	}
> > +
> > +	if (i == 0) {
> > +		ret = PTR_ERR(opp);
> > +		goto unlock;
> > +	}
> > +
> > +	cpufreq_device->cpu_dev = dev;
> > +	cpufreq_device->dyn_power_table = power_table;
> > +	cpufreq_device->dyn_power_table_entries = i;
> > +
> > +unlock:
> > +	rcu_read_unlock();
> > +	return ret;
> > +}
> > +
> > +static u32 cpu_freq_to_power(struct cpufreq_cooling_device *cpufreq_device,
> > +			     u32 freq)
> > +{
> > +	int i;
> > +	struct power_table *pt = cpufreq_device->dyn_power_table;
> > +
> > +	for (i = 1; i < cpufreq_device->dyn_power_table_entries; i++)
> > +		if (freq < pt[i].frequency)
> > +			break;
> > +
> > +	return pt[i - 1].power;
> > +}
> > +
> > +static u32 cpu_power_to_freq(struct cpufreq_cooling_device *cpufreq_device,
> > +			     u32 power)
> > +{
> > +	int i;
> > +	struct power_table *pt = cpufreq_device->dyn_power_table;
> > +
> > +	for (i = 1; i < cpufreq_device->dyn_power_table_entries; i++)
> > +		if (power < pt[i].power)
> > +			break;
> > +
> > +	return pt[i - 1].frequency;
> > +}
> > +
> > +/**
> > + * get_load() - get load for a cpu since last updated
> > + * @cpufreq_device:	&struct cpufreq_cooling_device for this cpu
> > + * @cpu:	cpu number
> > + *
> > + * Return: The average load of cpu @cpu in percentage since this
> > + * function was last called.
> > + */
> > +static u32 get_load(struct cpufreq_cooling_device *cpufreq_device, int cpu)
> > +{
> > +	u32 load;
> > +	u64 now, now_idle, delta_time, delta_idle;
> > +
> > +	now_idle = get_cpu_idle_time(cpu, &now, 0);
> > +	delta_idle = now_idle - cpufreq_device->time_in_idle[cpu];
> > +	delta_time = now - cpufreq_device->time_in_idle_timestamp[cpu];
> > +
> > +	if (delta_time <= delta_idle)
> > +		load = 0;
> > +	else
> > +		load = div64_u64(100 * (delta_time - delta_idle), delta_time);
> > +
> > +	cpufreq_device->time_in_idle[cpu] = now_idle;
> > +	cpufreq_device->time_in_idle_timestamp[cpu] = now;
> > +
> > +	return load;
> > +}
> > +
> > +/**
> > + * get_static_power() - calculate the static power consumed by the cpus
> > + * @cpufreq_device:	struct &cpufreq_cooling_device for this cpu cdev
> > + * @tz:		thermal zone device in which we're operating
> > + * @freq:	frequency in KHz
> > + * @power:	pointer in which to store the calculated static power
> > + *
> > + * Calculate the static power consumed by the cpus described by
> > + * @cpu_actor running at frequency @freq.  This function relies on a
> > + * platform specific function that should have been provided when the
> > + * actor was registered.  If it wasn't, the static power is assumed to
> > + * be negligible.  The calculated static power is stored in @power.
> > + *
> > + * Return: 0 on success, -E* on failure.
> > + */
> > +static int get_static_power(struct cpufreq_cooling_device *cpufreq_device,
> > +			    struct thermal_zone_device *tz, unsigned long freq,
> > +			    u32 *power)
> > +{
> > +	struct dev_pm_opp *opp;
> > +	unsigned long voltage;
> > +	struct cpumask *cpumask = &cpufreq_device->allowed_cpus;
> > +	unsigned long freq_hz = freq * 1000;
> > +
> > +	if (!cpufreq_device->plat_get_static_power) {
> > +		*power = 0;
> > +		return 0;
> > +	}
> > +
> > +	rcu_read_lock();
> > +
> > +	opp = dev_pm_opp_find_freq_exact(cpufreq_device->cpu_dev, freq_hz,
> > +					 true);
> > +	voltage = dev_pm_opp_get_voltage(opp);
> > +
> > +	rcu_read_unlock();
> > +
> > +	if (voltage == 0) {
> > +		dev_warn_ratelimited(cpufreq_device->cpu_dev,
> > +				     "Failed to get voltage for frequency %lu: %ld\n",
> > +				     freq_hz, IS_ERR(opp) ? PTR_ERR(opp) : 0);
> > +		return -EINVAL;
> > +	}
> > +
> > +	return cpufreq_device->plat_get_static_power(cpumask, tz->passive_delay,
> > +						     voltage, power);
> > +}
> > +
> > +/**
> > + * get_dynamic_power() - calculate the dynamic power
> > + * @cpufreq_device:	&cpufreq_cooling_device for this cdev
> > + * @freq:	current frequency
> > + *
> > + * Return: the dynamic power consumed by the cpus described by
> > + * @cpufreq_device.
> > + */
> > +static u32 get_dynamic_power(struct cpufreq_cooling_device *cpufreq_device,
> > +			     unsigned long freq)
> > +{
> > +	u32 raw_cpu_power;
> > +
> > +	raw_cpu_power = cpu_freq_to_power(cpufreq_device, freq);
> > +	return (raw_cpu_power * cpufreq_device->last_load) / 100;
> > +}
> > +
> >  /* cpufreq cooling device callback functions are defined below */
> >  
> >  /**
> > @@ -280,8 +514,161 @@ static int cpufreq_set_cur_state(struct thermal_cooling_device *cdev,
> >  	return 0;
> >  }
> >  
> > +/**
> > + * cpufreq_get_requested_power() - get the current power
> > + * @cdev:	&thermal_cooling_device pointer
> > + * @tz:		a valid thermal zone device pointer
> > + * @power:	pointer in which to store the resulting power
> > + *
> > + * Calculate the current power consumption of the cpus in milliwatts
> > + * and store it in @power.  This function should actually calculate
> > + * the requested power, but it's hard to get the frequency that
> > + * cpufreq would have assigned if there were no thermal limits.
> > + * Instead, we calculate the current power on the assumption that the
> > + * immediate future will look like the immediate past.
> > + *
> > + * Return: 0 on success, -E* if getting the static power failed.
> > + */
> > +static int cpufreq_get_requested_power(struct thermal_cooling_device *cdev,
> > +				       struct thermal_zone_device *tz,
> > +				       u32 *power)
> > +{
> > +	unsigned long freq;
> > +	int cpu, ret;
> > +	u32 static_power, dynamic_power, total_load = 0;
> > +	struct cpufreq_cooling_device *cpufreq_device = cdev->devdata;
> > +
> > +	freq = cpufreq_quick_get(cpumask_any(&cpufreq_device->allowed_cpus));
> > +
> > +	for_each_cpu(cpu, &cpufreq_device->allowed_cpus) {
> > +		u32 load;
> > +
> > +		if (cpu_online(cpu))
> > +			load = get_load(cpufreq_device, cpu);
> > +		else
> > +			load = 0;
> > +
> > +		total_load += load;
> > +	}
> > +
> > +	cpufreq_device->last_load = total_load;
> > +
> > +	dynamic_power = get_dynamic_power(cpufreq_device, freq);
> > +	ret = get_static_power(cpufreq_device, tz, freq, &static_power);
> > +	if (ret)
> > +		return ret;
> > +
> > +	*power = static_power + dynamic_power;
> > +	return 0;
> > +}
> 
> Repeating the query I've just made on v5, do we care if the system uses
> different opps during the load sampling interval? 
> 
> Meaning, 1 - idle might not reflect the correct load.

Similarly to what we discussed in the other thread, we know it's a
simplification and we haven't seen it affecting performance.  We will
add a comment that clarifies this in the code.

Cheers,
Javi

[PATCH v1 4/7] thermal: introduce the Power Allocator governor

[Javi Merino]

The power allocator governor is a thermal governor that controls system
and device power allocation to control temperature.  Conceptually, the
implementation divides the sustainable power of a thermal zone among
all the heat sources in that zone.

This governor relies on "power actors", entities that represent heat
sources.  They can report current and maximum power consumption and
can set a given maximum power consumption, usually via a cooling
device.

The governor uses a Proportional Integral Derivative (PID) controller
driven by the temperature of the thermal zone.  The output of the
controller is a power budget that is then allocated to each power
actor that can have bearing on the temperature we are trying to
control.  It decides how much power to give each cooling device based
on the performance they are requesting.  The PID controller ensures
that the total power budget does not exceed the control temperature.

Cc: Zhang Rui <rui.zhang@intel.com>
Cc: Eduardo Valentin <edubezval@gmail.com>
Signed-off-by: Punit Agrawal <punit.agrawal@arm.com>
Signed-off-by: Javi Merino <javi.merino@arm.com>
---
 Documentation/thermal/power_allocator.txt | 241 +++++++++++++++
 drivers/thermal/Kconfig                   |  15 +
 drivers/thermal/Makefile                  |   1 +
 drivers/thermal/power_allocator.c         | 478 ++++++++++++++++++++++++++++++
 drivers/thermal/thermal_core.c            |   9 +-
 drivers/thermal/thermal_core.h            |   8 +
 include/linux/thermal.h                   |  37 ++-
 7 files changed, 782 insertions(+), 7 deletions(-)
 create mode 100644 Documentation/thermal/power_allocator.txt
 create mode 100644 drivers/thermal/power_allocator.c

diff --git a/Documentation/thermal/power_allocator.txt b/Documentation/thermal/power_allocator.txt
new file mode 100644
index 000000000000..c9604e76c544
--- /dev/null
+++ b/Documentation/thermal/power_allocator.txt
@@ -0,0 +1,241 @@
+Power allocator governor tunables
+=================================
+
+Trip points
+-----------
+
+The governor requires the following two passive trip points:
+
+1.  "switch on" trip point: temperature above which the governor
+    control loop starts operating.
+2.  "desired temperature" trip point: it should be higher than the
+    "switch on" trip point.  This the target temperature the governor
+    is controlling for.
+
+PID Controller
+--------------
+
+The power allocator governor implements a
+Proportional-Integral-Derivative controller (PID controller) with
+temperature as the control input and power as the controlled output:
+
+    P_max = k_p * e + k_i * err_integral + k_d * diff_err + sustainable_power
+
+where
+    e = desired_temperature - current_temperature
+    err_integral is the sum of previous errors
+    diff_err = e - previous_error
+
+It is similar to the one depicted below:
+
+                                      k_d
+                                       |
+current_temp                           |
+     |                                 v
+     |                +----------+   +---+
+     |         +----->| diff_err |-->| X |------+
+     |         |      +----------+   +---+      |
+     |         |                                |      tdp        actor
+     |         |                      k_i       |       |  get_requested_power()
+     |         |                       |        |       |        |     |
+     |         |                       |        |       |        |     | ...
+     v         |                       v        v       v        v     v
+   +---+       |      +-------+      +---+    +---+   +---+   +----------+
+   | S |-------+----->| sum e |----->| X |--->| S |-->| S |-->|power     |
+   +---+       |      +-------+      +---+    +---+   +---+   |allocation|
+     ^         |                                ^             +----------+
+     |         |                                |                |     |
+     |         |        +---+                   |                |     |
+     |         +------->| X |-------------------+                v     v
+     |                  +---+                               granted performance
+desired_temperature       ^
+                          |
+                          |
+                      k_po/k_pu
+
+Sustainable power
+-----------------
+
+An estimate of the sustainable dissipatable power (in mW) should be
+provided while registering the thermal zone.  This estimates the
+sustained power that can be dissipated at the desired control
+temperature.  This is the maximum sustained power for allocation at
+the desired maximum temperature.  The actual sustained power can vary
+for a number of reasons.  The closed loop controller will take care of
+variations such as environmental conditions, and some factors related
+to the speed-grade of the silicon.  `sustainable_power` is therefore
+simply an estimate, and may be tuned to affect the aggressiveness of
+the thermal ramp. For reference, the sustainable power of a 4" phone
+is typically 2000mW, while on a 10" tablet is around 4500mW (may vary
+depending on screen size).
+
+If you are using device tree, do add it as a property of the
+thermal-zone.  For example:
+
+	thermal-zones {
+		soc_thermal {
+			polling-delay = <1000>;
+			polling-delay-passive = <100>;
+			sustainable-power = <2500>;
+			...
+
+Instead, if the thermal zone is registered from the platform code, pass a
+`thermal_zone_params` that has a `sustainable_power`.  If no
+`thermal_zone_params` were being passed, then something like below
+will suffice:
+
+	static const struct thermal_zone_params tz_params = {
+		.sustainable_power = 3500,
+	};
+
+and then pass `tz_params` as the 5th parameter to
+`thermal_zone_device_register()`
+
+k_po and k_pu
+-------------
+
+The implementation of the PID controller in the power allocator
+thermal governor allows the configuration of two proportional term
+constants: `k_po` and `k_pu`.  `k_po` is the proportional term
+constant during temperature overshoot periods (current temperature is
+above "desired temperature" trip point).  Conversely, `k_pu` is the
+proportional term constant during temperature undershoot periods
+(current temperature below "desired temperature" trip point).
+
+These controls are intended as the primary mechanism for configuring
+the permitted thermal "ramp" of the system.  For instance, a lower
+`k_pu` value will provide a slower ramp, at the cost of capping
+available capacity at a low temperature.  On the other hand, a high
+value of `k_pu` will result in the governor granting very high power
+whilst temperature is low, and may lead to temperature overshooting.
+
+The default value for `k_pu` is:
+
+    2 * sustainable_power / (desired_temperature - switch_on_temp)
+
+This means that at `switch_on_temp` the output of the controller's
+proportional term will be 2 * `sustainable_power`.  The default value
+for `k_po` is:
+
+    sustainable_power / (desired_temperature - switch_on_temp)
+
+Focusing on the proportional and feed forward values of the PID
+controller equation we have:
+
+    P_max = k_p * e + sustainable_power
+
+The proportional term is proportional to the difference between the
+desired temperature and the current one.  When the current temperature
+is the desired one, then the proportional component is zero and
+`P_max` = `sustainable_power`.  That is, the system should operate in
+thermal equilibrium under constant load.  `sustainable_power` is only
+an estimate, which is the reason for closed-loop control such as this.
+
+Expanding `k_pu` we get:
+    P_max = 2 * sustainable_power * (T_set - T) / (T_set - T_on) +
+        sustainable_power
+
+where
+    T_set is the desired temperature
+    T is the current temperature
+    T_on is the switch on temperature
+
+When the current temperature is the switch_on temperature, the above
+formula becomes:
+
+    P_max = 2 * sustainable_power * (T_set - T_on) / (T_set - T_on) +
+        sustainable_power = 2 * sustainable_power + sustainable_power =
+        3 * sustainable_power
+
+Therefore, the proportional term alone linearly decreases power from
+3 * `sustainable_power` to `sustainable_power` as the temperature
+rises from the switch on temperature to the desired temperature.
+
+k_i and integral_cutoff
+-----------------------
+
+`k_i` configures the PID loop's integral term constant.  This term
+allows the PID controller to compensate for long term drift and for
+the quantized nature of the output control: cooling devices can't set
+the exact power that the governor requests.  When the temperature
+error is below `integral_cutoff`, errors are accumulated in the
+integral term.  This term is then multiplied by `k_i` and the result
+added to the output of the controller.  Typically `k_i` is set low (1
+or 2) and `integral_cutoff` is 0.
+
+k_d
+---
+
+`k_d` configures the PID loop's derivative term constant.  It's
+recommended to leave it as the default: 0.
+
+Cooling device power API
+========================
+
+Cooling devices controlled by this governor must supply the additional
+"power" API in their `cooling_device_ops`.  It consists on three ops:
+
+1. int get_requested_power(struct thermal_cooling_device *cdev,
+	struct thermal_zone_device *tz, u32 *power);
+@cdev: The `struct thermal_cooling_device` pointer
+@tz: thermal zone in which we are currently operating
+@power: pointer in which to store the calculated power
+
+`get_requested_power()` calculates the power requested by the device
+in milliwatts and stores it in @power .  It should return 0 on
+success, -E* on failure.  This is currently used by the power
+allocator governor to calculate how much power to give to each cooling
+device.
+
+2. int state2power(struct thermal_cooling_device *cdev, struct
+        thermal_zone_device *tz, unsigned long state, u32 *power);
+@cdev: The `struct thermal_cooling_device` pointer
+@tz: thermal zone in which we are currently operating
+@state: A cooling device state
+@power: pointer in which to store the equivalent power
+
+Convert cooling device state @state into power consumption in
+milliwatts and store it in @power.  It should return 0 on success, -E*
+on failure.  This is currently used by thermal core to calculate the
+maximum power that an actor can consume.
+
+3. int power2state(struct thermal_cooling_device *cdev, u32 power,
+	unsigned long *state);
+@cdev: The `struct thermal_cooling_device` pointer
+@power: power in milliwatts
+@state: pointer in which to store the resulting state
+
+Calculate a cooling device state that would make the device consume at
+most @power mW and store it in @state.  It should return 0 on success,
+-E* on failure.  This is currently used by the thermal core to convert
+a given power set by the power allocator governor to a state that the
+cooling device can set.  It is a function because this conversion may
+depend on external factors that may change so this function should the
+best conversion given "current circumstances".
+
+Cooling device weights
+----------------------
+
+Weights are a mechanism to bias the allocation among cooling
+devices.  They express the relative power efficiency of different
+cooling devices.  Higher weight can be used to express higher power
+efficiency.  Weighting is relative such that if each cooling device
+has a weight of one they are considered equal.  This is particularly
+useful in heterogeneous systems where two cooling devices may perform
+the same kind of compute, but with different efficiency.  For example,
+a system with two different types of processors.
+
+Weights are passed as part of the thermal zone's
+`thermal_bind_parameters`.
+
+Limitations of the power allocator governor
+===========================================
+
+The power allocator governor's PID controller works best if there is a
+periodic tick.  If you have a driver that calls
+`thermal_zone_device_update()` (or anything that ends up calling the
+governor's `throttle()` function) repetitively, the governor response
+won't be very good.  Note that this is not particular to this
+governor, step-wise will also misbehave if you call its throttle()
+faster than the normal thermal framework tick (due to interrupts for
+example) as it will overreact.
diff --git a/drivers/thermal/Kconfig b/drivers/thermal/Kconfig
index af40db0df58e..98a46383b19f 100644
--- a/drivers/thermal/Kconfig
+++ b/drivers/thermal/Kconfig
@@ -71,6 +71,14 @@ config THERMAL_DEFAULT_GOV_USER_SPACE
 	  Select this if you want to let the user space manage the
 	  platform thermals.
 
+config THERMAL_DEFAULT_GOV_POWER_ALLOCATOR
+	bool "power_allocator"
+	select THERMAL_GOV_POWER_ALLOCATOR
+	help
+	  Select this if you want to control temperature based on
+	  system and device power allocation. This governor can only
+	  operate on cooling devices that implement the power API.
+
 endchoice
 
 config THERMAL_GOV_FAIR_SHARE
@@ -99,6 +107,13 @@ config THERMAL_GOV_USER_SPACE
 	help
 	  Enable this to let the user space manage the platform thermals.
 
+config THERMAL_GOV_POWER_ALLOCATOR
+	bool "Power allocator thermal governor"
+	select THERMAL_POWER_ACTOR
+	help
+	  Enable this to manage platform thermals by dynamically
+	  allocating and limiting power to devices.
+
 config CPU_THERMAL
 	bool "generic cpu cooling support"
 	depends on CPU_FREQ
diff --git a/drivers/thermal/Makefile b/drivers/thermal/Makefile
index fa0dc486790f..cd769ab06cbb 100644
--- a/drivers/thermal/Makefile
+++ b/drivers/thermal/Makefile
@@ -14,6 +14,7 @@ thermal_sys-$(CONFIG_THERMAL_GOV_FAIR_SHARE)	+= fair_share.o
 thermal_sys-$(CONFIG_THERMAL_GOV_BANG_BANG)	+= gov_bang_bang.o
 thermal_sys-$(CONFIG_THERMAL_GOV_STEP_WISE)	+= step_wise.o
 thermal_sys-$(CONFIG_THERMAL_GOV_USER_SPACE)	+= user_space.o
+thermal_sys-$(CONFIG_THERMAL_GOV_POWER_ALLOCATOR)	+= power_allocator.o
 
 # cpufreq cooling
 thermal_sys-$(CONFIG_CPU_THERMAL)	+= cpu_cooling.o
diff --git a/drivers/thermal/power_allocator.c b/drivers/thermal/power_allocator.c
new file mode 100644
index 000000000000..c929143aee67
--- /dev/null
+++ b/drivers/thermal/power_allocator.c
@@ -0,0 +1,478 @@
+/*
+ * A power allocator to manage temperature
+ *
+ * Copyright (C) 2014 ARM Ltd.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ * This program is distributed "as is" WITHOUT ANY WARRANTY of any
+ * kind, whether express or implied; without even the implied warranty
+ * of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ */
+
+#define pr_fmt(fmt) "Power allocator: " fmt
+
+#include <linux/rculist.h>
+#include <linux/slab.h>
+#include <linux/thermal.h>
+
+#include "thermal_core.h"
+
+#define FRAC_BITS 10
+#define int_to_frac(x) ((x) << FRAC_BITS)
+#define frac_to_int(x) ((x) >> FRAC_BITS)
+
+/**
+ * mul_frac() - multiply two fixed-point numbers
+ * @x:	first multiplicand
+ * @y:	second multiplicand
+ *
+ * Return: the result of multiplying two fixed-point numbers.  The
+ * result is also a fixed-point number.
+ */
+static inline s64 mul_frac(s64 x, s64 y)
+{
+	return (x * y) >> FRAC_BITS;
+}
+
+enum power_allocator_trip_levels {
+	TRIP_SWITCH_ON = 0,	/* Switch on PID controller */
+	TRIP_MAX_DESIRED_TEMPERATURE, /* Temperature we are controlling for */
+
+	THERMAL_TRIP_NUM,
+};
+
+/**
+ * struct power_allocator_params - parameters for the power allocator governor
+ * @err_integral:	accumulated error in the PID controller.
+ * @prev_err:	error in the previous iteration of the PID controller.
+ *		Used to calculate the derivative term.
+ */
+struct power_allocator_params {
+	s64 err_integral;
+	s32 prev_err;
+};
+
+/**
+ * pid_controller() - PID controller
+ * @tz:	thermal zone we are operating in
+ * @current_temp:	the current temperature in millicelsius
+ * @control_temp:	the target temperature in millicelsius
+ * @max_allocatable_power:	maximum allocatable power for this thermal zone
+ *
+ * This PID controller increases the available power budget so that the
+ * temperature of the thermal zone gets as close as possible to
+ * @control_temp and limits the power if it exceeds it.  k_po is the
+ * proportional term when we are overshooting, k_pu is the
+ * proportional term when we are undershooting.  integral_cutoff is a
+ * threshold below which we stop accumulating the error.  The
+ * accumulated error is only valid if the requested power will make
+ * the system warmer.  If the system is mostly idle, there's no point
+ * in accumulating positive error.
+ *
+ * Return: The power budget for the next period.
+ */
+static u32 pid_controller(struct thermal_zone_device *tz,
+			  unsigned long current_temp,
+			  unsigned long control_temp,
+			  u32 max_allocatable_power)
+{
+	s64 p, i, d, power_range;
+	s32 err, max_power_frac;
+	struct power_allocator_params *params = tz->governor_data;
+
+	max_power_frac = int_to_frac(max_allocatable_power);
+
+	err = ((s32)control_temp - (s32)current_temp);
+	err = int_to_frac(err);
+
+	/* Calculate the proportional term */
+	p = mul_frac(err < 0 ? tz->tzp->k_po : tz->tzp->k_pu, err);
+
+	/*
+	 * Calculate the integral term
+	 *
+	 * if the error is less than cut off allow integration (but
+	 * the integral is limited to max power)
+	 */
+	i = mul_frac(tz->tzp->k_i, params->err_integral);
+
+	if (err < int_to_frac(tz->tzp->integral_cutoff)) {
+		s64 i_next = i + mul_frac(tz->tzp->k_i, err);
+
+		if (abs64(i_next) < max_power_frac) {
+			i = i_next;
+			params->err_integral += err;
+		}
+	}
+
+	/*
+	 * Calculate the derivative term
+	 *
+	 * We do err - prev_err, so with a positive k_d, a decreasing
+	 * error (i.e. driving closer to the line) results in less
+	 * power being applied, slowing down the controller)
+	 */
+	d = mul_frac(tz->tzp->k_d, err - params->prev_err);
+	params->prev_err = err;
+
+	power_range = p + i + d;
+
+	/* feed-forward the known sustainable dissipatable power */
+	power_range = tz->tzp->sustainable_power + frac_to_int(power_range);
+
+	return clamp(power_range, (s64)0, (s64)max_allocatable_power);
+}
+
+/**
+ * divvy_up_power() - divvy the allocated power between the actors
+ * @req_power:	each actor's requested power
+ * @max_power:	each actor's maximum available power
+ * @num_actors:	size of the @req_power, @max_power and @granted_power's array
+ * @total_req_power: sum of @req_power
+ * @power_range:	total allocated power
+ * @granted_power:	output array: each actor's granted power
+ *
+ * This function divides the total allocated power (@power_range)
+ * fairly between the actors.  It first tries to give each actor a
+ * share of the @power_range according to how much power it requested
+ * compared to the rest of the actors.  For example, if only one actor
+ * requests power, then it receives all the @power_range.  If
+ * three actors each requests 1mW, each receives a third of the
+ * @power_range.
+ *
+ * If any actor received more than their maximum power, then that
+ * surplus is re-divvied among the actors based on how far they are
+ * from their respective maximums.
+ *
+ * Granted power for each actor is written to @granted_power, which
+ * should've been allocated by the calling function.
+ */
+static void divvy_up_power(u32 *req_power, u32 *max_power, int num_actors,
+			   u32 total_req_power, u32 power_range,
+			   u32 *granted_power)
+{
+	u32 extra_power, capped_extra_power, extra_actor_power[num_actors];
+	int i;
+
+	/*
+	 * Prevent division by 0 if none of the actors request power.
+	 */
+	if (!total_req_power)
+		total_req_power = 1;
+
+	capped_extra_power = 0;
+	extra_power = 0;
+	for (i = 0; i < num_actors; i++) {
+		u64 req_range = req_power[i] * power_range;
+
+		granted_power[i] = div_u64(req_range, total_req_power);
+
+		if (granted_power[i] > max_power[i]) {
+			extra_power += granted_power[i] - max_power[i];
+			granted_power[i] = max_power[i];
+		}
+
+		extra_actor_power[i] = max_power[i] - granted_power[i];
+		capped_extra_power += extra_actor_power[i];
+	}
+
+	if (!extra_power)
+		return;
+
+	/*
+	 * Re-divvy the reclaimed extra among actors based on
+	 * how far they are from the max
+	 */
+	extra_power = min(extra_power, capped_extra_power);
+	if (capped_extra_power > 0)
+		for (i = 0; i < num_actors; i++)
+			granted_power[i] += (extra_actor_power[i] *
+					extra_power) / capped_extra_power;
+}
+
+static int allocate_power(struct thermal_zone_device *tz,
+			  unsigned long current_temp,
+			  unsigned long control_temp)
+{
+	struct thermal_instance *instance;
+	u32 *req_power, *max_power, *granted_power;
+	u32 total_req_power, max_allocatable_power;
+	u32 power_range;
+	int i, num_actors, ret = 0;
+
+	mutex_lock(&tz->lock);
+
+	num_actors = 0;
+	list_for_each_entry(instance, &tz->thermal_instances, tz_node)
+		if ((instance->trip == TRIP_MAX_DESIRED_TEMPERATURE) &&
+		    cdev_is_power_actor(instance->cdev))
+			num_actors++;
+
+	req_power = devm_kcalloc(&tz->device, num_actors, sizeof(*req_power),
+				 GFP_KERNEL);
+	if (!req_power) {
+		ret = -ENOMEM;
+		goto unlock;
+	}
+
+	max_power = devm_kcalloc(&tz->device, num_actors, sizeof(*max_power),
+				 GFP_KERNEL);
+	if (!max_power) {
+		ret = -ENOMEM;
+		goto free_req_power;
+	}
+
+	granted_power = devm_kcalloc(&tz->device, num_actors,
+				     sizeof(*granted_power), GFP_KERNEL);
+	if (!granted_power) {
+		ret = -ENOMEM;
+		goto free_max_power;
+	}
+
+	i = 0;
+	total_req_power = 0;
+	max_allocatable_power = 0;
+
+	list_for_each_entry(instance, &tz->thermal_instances, tz_node) {
+		struct thermal_cooling_device *cdev = instance->cdev;
+
+		if (instance->trip != TRIP_MAX_DESIRED_TEMPERATURE)
+			continue;
+
+		if (!cdev_is_power_actor(cdev))
+			continue;
+
+		if (cdev->ops->get_requested_power(cdev, tz, &req_power[i]))
+			continue;
+
+		req_power[i] = frac_to_int(instance->weight * req_power[i]);
+
+		if (power_actor_get_max_power(cdev, tz, &max_power[i]))
+			continue;
+
+		total_req_power += req_power[i];
+		max_allocatable_power += max_power[i];
+
+		i++;
+	}
+
+	power_range = pid_controller(tz, current_temp, control_temp,
+				     max_allocatable_power);
+
+	divvy_up_power(req_power, max_power, num_actors, total_req_power,
+		       power_range, granted_power);
+
+	i = 0;
+	list_for_each_entry(instance, &tz->thermal_instances, tz_node) {
+		if (instance->trip != TRIP_MAX_DESIRED_TEMPERATURE)
+			continue;
+
+		if (!cdev_is_power_actor(instance->cdev))
+			continue;
+
+		power_actor_set_power(instance->cdev, instance,
+				      granted_power[i]);
+
+		i++;
+	}
+
+	devm_kfree(&tz->device, granted_power);
+free_max_power:
+	devm_kfree(&tz->device, max_power);
+free_req_power:
+	devm_kfree(&tz->device, req_power);
+unlock:
+	mutex_unlock(&tz->lock);
+
+	return ret;
+}
+
+static int check_trips(struct thermal_zone_device *tz)
+{
+	int ret;
+	enum thermal_trip_type type;
+
+	if (tz->trips < THERMAL_TRIP_NUM)
+		return -EINVAL;
+
+	ret = tz->ops->get_trip_type(tz, TRIP_SWITCH_ON, &type);
+	if (ret)
+		return ret;
+
+	if (type != THERMAL_TRIP_PASSIVE)
+		return -EINVAL;
+
+	ret = tz->ops->get_trip_type(tz, TRIP_MAX_DESIRED_TEMPERATURE, &type);
+	if (ret)
+		return ret;
+
+	if (type != THERMAL_TRIP_PASSIVE)
+		return -EINVAL;
+
+	return ret;
+}
+
+static void reset_pid_controller(struct power_allocator_params *params)
+{
+	params->err_integral = 0;
+	params->prev_err = 0;
+}
+
+static void allow_maximum_power(struct thermal_zone_device *tz)
+{
+	struct thermal_instance *instance;
+
+	list_for_each_entry(instance, &tz->thermal_instances, tz_node) {
+		if ((instance->trip != TRIP_MAX_DESIRED_TEMPERATURE) ||
+		    (!cdev_is_power_actor(instance->cdev)))
+			continue;
+
+		instance->target = 0;
+		instance->cdev->updated = false;
+		thermal_cdev_update(instance->cdev);
+	}
+}
+
+/**
+ * power_allocator_bind() - bind the power_allocator governor to a thermal zone
+ * @tz:	thermal zone to bind it to
+ *
+ * Check that the thermal zone is valid for this governor, that is, it
+ * has two thermal trips.  If so, initialize the PID controller
+ * parameters and bind it to the thermal zone.
+ *
+ * Return: 0 on success, -EINVAL if the trips were invalid or -ENOMEM
+ * if we ran out of memory.
+ */
+static int power_allocator_bind(struct thermal_zone_device *tz)
+{
+	int ret;
+	struct power_allocator_params *params;
+	unsigned long switch_on_temp, control_temp;
+	u32 temperature_threshold;
+
+	ret = check_trips(tz);
+	if (ret) {
+		dev_err(&tz->device,
+			"thermal zone %s has wrong trip setup for power allocator\n",
+			tz->type);
+		return ret;
+	}
+
+	if (!tz->tzp || !tz->tzp->sustainable_power) {
+		dev_err(&tz->device,
+			"power_allocator: missing sustainable_power\n");
+		return -EINVAL;
+	}
+
+	params = devm_kzalloc(&tz->device, sizeof(*params), GFP_KERNEL);
+	if (!params)
+		return -ENOMEM;
+
+	ret = tz->ops->get_trip_temp(tz, TRIP_SWITCH_ON, &switch_on_temp);
+	if (ret)
+		goto free;
+
+	ret = tz->ops->get_trip_temp(tz, TRIP_MAX_DESIRED_TEMPERATURE,
+				&control_temp);
+	if (ret)
+		goto free;
+
+	temperature_threshold = control_temp - switch_on_temp;
+
+	tz->tzp->k_po = tz->tzp->k_po ?:
+		int_to_frac(tz->tzp->sustainable_power) / temperature_threshold;
+	tz->tzp->k_pu = tz->tzp->k_pu ?:
+		int_to_frac(2 * tz->tzp->sustainable_power) /
+		temperature_threshold;
+	tz->tzp->k_i = tz->tzp->k_i ?: int_to_frac(10) / 1000;
+	/*
+	 * The default for k_d and integral_cutoff is 0, so we can
+	 * leave them as they are.
+	 */
+
+	reset_pid_controller(params);
+
+	tz->governor_data = params;
+
+	return 0;
+
+free:
+	devm_kfree(&tz->device, params);
+	return ret;
+}
+
+static void power_allocator_unbind(struct thermal_zone_device *tz)
+{
+	dev_dbg(&tz->device, "Unbinding from thermal zone %d\n", tz->id);
+	devm_kfree(&tz->device, tz->governor_data);
+	tz->governor_data = NULL;
+}
+
+static int power_allocator_throttle(struct thermal_zone_device *tz, int trip)
+{
+	int ret;
+	unsigned long switch_on_temp, control_temp, current_temp;
+	struct power_allocator_params *params = tz->governor_data;
+
+	/*
+	 * We get called for every trip point but we only need to do
+	 * our calculations once
+	 */
+	if (trip != TRIP_MAX_DESIRED_TEMPERATURE)
+		return 0;
+
+	ret = thermal_zone_get_temp(tz, &current_temp);
+	if (ret) {
+		dev_warn(&tz->device, "Failed to get temperature: %d\n", ret);
+		return ret;
+	}
+
+	ret = tz->ops->get_trip_temp(tz, TRIP_SWITCH_ON, &switch_on_temp);
+	if (ret) {
+		dev_warn(&tz->device,
+			 "Failed to get switch on temperature: %d\n", ret);
+		return ret;
+	}
+
+	if (current_temp < switch_on_temp) {
+		tz->passive = 0;
+		reset_pid_controller(params);
+		allow_maximum_power(tz);
+		return 0;
+	}
+
+	tz->passive = 1;
+
+	ret = tz->ops->get_trip_temp(tz, TRIP_MAX_DESIRED_TEMPERATURE,
+				&control_temp);
+	if (ret) {
+		dev_warn(&tz->device,
+			 "Failed to get the maximum desired temperature: %d\n",
+			 ret);
+		return ret;
+	}
+
+	return allocate_power(tz, current_temp, control_temp);
+}
+
+static struct thermal_governor thermal_gov_power_allocator = {
+	.name		= "power_allocator",
+	.bind_to_tz	= power_allocator_bind,
+	.unbind_from_tz	= power_allocator_unbind,
+	.throttle	= power_allocator_throttle,
+};
+
+int thermal_gov_power_allocator_register(void)
+{
+	return thermal_register_governor(&thermal_gov_power_allocator);
+}
+
+void thermal_gov_power_allocator_unregister(void)
+{
+	thermal_unregister_governor(&thermal_gov_power_allocator);
+}
diff --git a/drivers/thermal/thermal_core.c b/drivers/thermal/thermal_core.c
index a01d4a72bd93..b77b5416929c 100644
--- a/drivers/thermal/thermal_core.c
+++ b/drivers/thermal/thermal_core.c
@@ -1567,7 +1567,7 @@ static void remove_trip_attrs(struct thermal_zone_device *tz)
 struct thermal_zone_device *thermal_zone_device_register(const char *type,
 	int trips, int mask, void *devdata,
 	struct thermal_zone_device_ops *ops,
-	const struct thermal_zone_params *tzp,
+	struct thermal_zone_params *tzp,
 	int passive_delay, int polling_delay)
 {
 	struct thermal_zone_device *tz;
@@ -1923,7 +1923,11 @@ static int __init thermal_register_governors(void)
 	if (result)
 		return result;
 
-	return thermal_gov_user_space_register();
+	result = thermal_gov_user_space_register();
+	if (result)
+		return result;
+
+	return thermal_gov_power_allocator_register();
 }
 
 static void thermal_unregister_governors(void)
@@ -1932,6 +1936,7 @@ static void thermal_unregister_governors(void)
 	thermal_gov_fair_share_unregister();
 	thermal_gov_bang_bang_unregister();
 	thermal_gov_user_space_unregister();
+	thermal_gov_power_allocator_unregister();
 }
 
 static int __init thermal_init(void)
diff --git a/drivers/thermal/thermal_core.h b/drivers/thermal/thermal_core.h
index 0531c752fbbb..28aa326806eb 100644
--- a/drivers/thermal/thermal_core.h
+++ b/drivers/thermal/thermal_core.h
@@ -85,6 +85,14 @@ static inline int thermal_gov_user_space_register(void) { return 0; }
 static inline void thermal_gov_user_space_unregister(void) {}
 #endif /* CONFIG_THERMAL_GOV_USER_SPACE */
 
+#ifdef CONFIG_THERMAL_GOV_POWER_ALLOCATOR
+int thermal_gov_power_allocator_register(void);
+void thermal_gov_power_allocator_unregister(void);
+#else
+static inline int thermal_gov_power_allocator_register(void) { return 0; }
+static inline void thermal_gov_power_allocator_unregister(void) {}
+#endif /* CONFIG_THERMAL_GOV_POWER_ALLOCATOR */
+
 /* device tree support */
 #ifdef CONFIG_THERMAL_OF
 int of_parse_thermal_zones(void);
diff --git a/include/linux/thermal.h b/include/linux/thermal.h
index 288ac6fd743d..b42f790bb23c 100644
--- a/include/linux/thermal.h
+++ b/include/linux/thermal.h
@@ -56,6 +56,8 @@
 #define DEFAULT_THERMAL_GOVERNOR       "fair_share"
 #elif defined(CONFIG_THERMAL_DEFAULT_GOV_USER_SPACE)
 #define DEFAULT_THERMAL_GOVERNOR       "user_space"
+#elif defined(CONFIG_THERMAL_DEFAULT_GOV_POWER_ALLOCATOR)
+#define DEFAULT_THERMAL_GOVERNOR       "power_allocator"
 #endif
 
 struct thermal_zone_device;
@@ -151,8 +153,7 @@ struct thermal_attr {
  * @devdata:	private pointer for device private data
  * @trips:	number of trip points the thermal zone supports
  * @passive_delay:	number of milliseconds to wait between polls when
- *			performing passive cooling.  Currenty only used by the
- *			step-wise governor
+ *			performing passive cooling.
  * @polling_delay:	number of milliseconds to wait between polls when
  *			checking whether trip points have been crossed (0 for
  *			interrupt driven systems)
@@ -162,7 +163,6 @@ struct thermal_attr {
  * @last_temperature:	previous temperature read
  * @emul_temperature:	emulated temperature when using CONFIG_THERMAL_EMULATION
  * @passive:		1 if you've crossed a passive trip point, 0 otherwise.
- *			Currenty only used by the step-wise governor.
  * @forced_passive:	If > 0, temperature at which to switch on all ACPI
  *			processor cooling devices.  Currently only used by the
  *			step-wise governor.
@@ -194,7 +194,7 @@ struct thermal_zone_device {
 	int passive;
 	unsigned int forced_passive;
 	struct thermal_zone_device_ops *ops;
-	const struct thermal_zone_params *tzp;
+	struct thermal_zone_params *tzp;
 	struct thermal_governor *governor;
 	void *governor_data;
 	struct list_head thermal_instances;
@@ -269,6 +269,33 @@ struct thermal_zone_params {
 
 	int num_tbps;	/* Number of tbp entries */
 	struct thermal_bind_params *tbp;
+
+	/*
+	 * Sustainable power (heat) that this thermal zone can dissipate in
+	 * mW
+	 */
+	u32 sustainable_power;
+
+	/*
+	 * Proportional parameter of the PID controller when
+	 * overshooting (i.e., when temperature is below the target)
+	 */
+	s32 k_po;
+
+	/*
+	 * Proportional parameter of the PID controller when
+	 * undershooting
+	 */
+	s32 k_pu;
+
+	/* Integral parameter of the PID controller */
+	s32 k_i;
+
+	/* Derivative parameter of the PID controller */
+	s32 k_d;
+
+	/* threshold below which the error is no longer accumulated */
+	s32 integral_cutoff;
 };
 
 struct thermal_genl_event {
@@ -343,7 +370,7 @@ int power_actor_set_power(struct thermal_cooling_device *,
 			  struct thermal_instance *, u32);
 struct thermal_zone_device *thermal_zone_device_register(const char *, int, int,
 		void *, struct thermal_zone_device_ops *,
-		const struct thermal_zone_params *, int, int);
+		struct thermal_zone_params *, int, int);
 void thermal_zone_device_unregister(struct thermal_zone_device *);
 
 int thermal_zone_bind_cooling_device(struct thermal_zone_device *, int,
-- 
1.9.1

Re: [PATCH v1 4/7] thermal: introduce the Power Allocator governor

[Lina Iyer]

On Wed, Jan 28 2015 at 14:42 -0700, Javi Merino wrote:
>The power allocator governor is a thermal governor that controls system
>and device power allocation to control temperature.  Conceptually, the
>implementation divides the sustainable power of a thermal zone among
>all the heat sources in that zone.
>
>This governor relies on "power actors", entities that represent heat
>sources.  They can report current and maximum power consumption and
>can set a given maximum power consumption, usually via a cooling
>device.
>
>The governor uses a Proportional Integral Derivative (PID) controller
>driven by the temperature of the thermal zone.  The output of the
>controller is a power budget that is then allocated to each power
>actor that can have bearing on the temperature we are trying to
>control.  It decides how much power to give each cooling device based
>on the performance they are requesting.  The PID controller ensures
>that the total power budget does not exceed the control temperature.
>
>Cc: Zhang Rui <rui.zhang@intel.com>
>Cc: Eduardo Valentin <edubezval@gmail.com>
>Signed-off-by: Punit Agrawal <punit.agrawal@arm.com>
>Signed-off-by: Javi Merino <javi.merino@arm.com>
>---
> Documentation/thermal/power_allocator.txt | 241 +++++++++++++++
> drivers/thermal/Kconfig                   |  15 +
> drivers/thermal/Makefile                  |   1 +
> drivers/thermal/power_allocator.c         | 478 ++++++++++++++++++++++++++++++
> drivers/thermal/thermal_core.c            |   9 +-
> drivers/thermal/thermal_core.h            |   8 +
> include/linux/thermal.h                   |  37 ++-
> 7 files changed, 782 insertions(+), 7 deletions(-)
> create mode 100644 Documentation/thermal/power_allocator.txt
> create mode 100644 drivers/thermal/power_allocator.c
>
>diff --git a/Documentation/thermal/power_allocator.txt b/Documentation/thermal/power_allocator.txt
>new file mode 100644
>index 000000000000..c9604e76c544
>--- /dev/null
>+++ b/Documentation/thermal/power_allocator.txt
>@@ -0,0 +1,241 @@
>+Power allocator governor tunables
>+=================================
>+
>+Trip points
>+-----------
>+
>+The governor requires the following two passive trip points:
>+
>+1.  "switch on" trip point: temperature above which the governor
>+    control loop starts operating.
>+2.  "desired temperature" trip point: it should be higher than the
>+    "switch on" trip point.  This the target temperature the governor
>+    is controlling for.
>+
>+PID Controller
>+--------------
>+
>+The power allocator governor implements a
>+Proportional-Integral-Derivative controller (PID controller) with
>+temperature as the control input and power as the controlled output:
>+
>+    P_max = k_p * e + k_i * err_integral + k_d * diff_err + sustainable_power
>+
>+where
>+    e = desired_temperature - current_temperature
>+    err_integral is the sum of previous errors
>+    diff_err = e - previous_error
>+
>+It is similar to the one depicted below:
>+
>+                                      k_d
>+                                       |
>+current_temp                           |
>+     |                                 v
>+     |                +----------+   +---+
>+     |         +----->| diff_err |-->| X |------+
>+     |         |      +----------+   +---+      |
>+     |         |                                |      tdp        actor
>+     |         |                      k_i       |       |  get_requested_power()
>+     |         |                       |        |       |        |     |
>+     |         |                       |        |       |        |     | ...
>+     v         |                       v        v       v        v     v
>+   +---+       |      +-------+      +---+    +---+   +---+   +----------+
>+   | S |-------+----->| sum e |----->| X |--->| S |-->| S |-->|power     |
>+   +---+       |      +-------+      +---+    +---+   +---+   |allocation|
>+     ^         |                                ^             +----------+
>+     |         |                                |                |     |
>+     |         |        +---+                   |                |     |
>+     |         +------->| X |-------------------+                v     v
>+     |                  +---+                               granted performance
>+desired_temperature       ^
>+                          |
>+                          |
>+                      k_po/k_pu
>+
>+Sustainable power
>+-----------------
>+
>+An estimate of the sustainable dissipatable power (in mW) should be
>+provided while registering the thermal zone.  This estimates the
>+sustained power that can be dissipated at the desired control
>+temperature.  This is the maximum sustained power for allocation at
>+the desired maximum temperature.  The actual sustained power can vary
>+for a number of reasons.  The closed loop controller will take care of
>+variations such as environmental conditions, and some factors related
>+to the speed-grade of the silicon.  `sustainable_power` is therefore
>+simply an estimate, and may be tuned to affect the aggressiveness of
>+the thermal ramp. For reference, the sustainable power of a 4" phone
>+is typically 2000mW, while on a 10" tablet is around 4500mW (may vary
>+depending on screen size).
>+
>+If you are using device tree, do add it as a property of the
>+thermal-zone.  For example:
>+
>+	thermal-zones {
>+		soc_thermal {
>+			polling-delay = <1000>;
>+			polling-delay-passive = <100>;
>+			sustainable-power = <2500>;
>+			...
>+
>+Instead, if the thermal zone is registered from the platform code, pass a
>+`thermal_zone_params` that has a `sustainable_power`.  If no
>+`thermal_zone_params` were being passed, then something like below
>+will suffice:
>+
>+	static const struct thermal_zone_params tz_params = {
>+		.sustainable_power = 3500,
>+	};
>+
>+and then pass `tz_params` as the 5th parameter to
>+`thermal_zone_device_register()`
>+
>+k_po and k_pu
>+-------------
>+
>+The implementation of the PID controller in the power allocator
>+thermal governor allows the configuration of two proportional term
>+constants: `k_po` and `k_pu`.  `k_po` is the proportional term
>+constant during temperature overshoot periods (current temperature is
>+above "desired temperature" trip point).  Conversely, `k_pu` is the
>+proportional term constant during temperature undershoot periods
>+(current temperature below "desired temperature" trip point).
>+
>+These controls are intended as the primary mechanism for configuring
>+the permitted thermal "ramp" of the system.  For instance, a lower
>+`k_pu` value will provide a slower ramp, at the cost of capping
>+available capacity at a low temperature.  On the other hand, a high
>+value of `k_pu` will result in the governor granting very high power
>+whilst temperature is low, and may lead to temperature overshooting.
>+
>+The default value for `k_pu` is:
>+
>+    2 * sustainable_power / (desired_temperature - switch_on_temp)
>+
>+This means that at `switch_on_temp` the output of the controller's
>+proportional term will be 2 * `sustainable_power`.  The default value
>+for `k_po` is:
>+
>+    sustainable_power / (desired_temperature - switch_on_temp)
>+
>+Focusing on the proportional and feed forward values of the PID
>+controller equation we have:
>+
>+    P_max = k_p * e + sustainable_power
>+
>+The proportional term is proportional to the difference between the
>+desired temperature and the current one.  When the current temperature
>+is the desired one, then the proportional component is zero and
>+`P_max` = `sustainable_power`.  That is, the system should operate in
>+thermal equilibrium under constant load.  `sustainable_power` is only
>+an estimate, which is the reason for closed-loop control such as this.
>+
>+Expanding `k_pu` we get:
>+    P_max = 2 * sustainable_power * (T_set - T) / (T_set - T_on) +
>+        sustainable_power
>+
>+where
>+    T_set is the desired temperature
>+    T is the current temperature
>+    T_on is the switch on temperature
>+
>+When the current temperature is the switch_on temperature, the above
>+formula becomes:
>+
>+    P_max = 2 * sustainable_power * (T_set - T_on) / (T_set - T_on) +
>+        sustainable_power = 2 * sustainable_power + sustainable_power =
>+        3 * sustainable_power
>+
>+Therefore, the proportional term alone linearly decreases power from
>+3 * `sustainable_power` to `sustainable_power` as the temperature
>+rises from the switch on temperature to the desired temperature.
>+
>+k_i and integral_cutoff
>+-----------------------
>+
>+`k_i` configures the PID loop's integral term constant.  This term
>+allows the PID controller to compensate for long term drift and for
>+the quantized nature of the output control: cooling devices can't set
>+the exact power that the governor requests.  When the temperature
>+error is below `integral_cutoff`, errors are accumulated in the
>+integral term.  This term is then multiplied by `k_i` and the result
>+added to the output of the controller.  Typically `k_i` is set low (1
>+or 2) and `integral_cutoff` is 0.
>+
>+k_d
>+---
>+
>+`k_d` configures the PID loop's derivative term constant.  It's
>+recommended to leave it as the default: 0.
>+
>+Cooling device power API
>+========================
>+
>+Cooling devices controlled by this governor must supply the additional
>+"power" API in their `cooling_device_ops`.  It consists on three ops:
>+
>+1. int get_requested_power(struct thermal_cooling_device *cdev,
>+	struct thermal_zone_device *tz, u32 *power);
>+@cdev: The `struct thermal_cooling_device` pointer
>+@tz: thermal zone in which we are currently operating
>+@power: pointer in which to store the calculated power
>+
>+`get_requested_power()` calculates the power requested by the device
>+in milliwatts and stores it in @power .  It should return 0 on
>+success, -E* on failure.  This is currently used by the power
>+allocator governor to calculate how much power to give to each cooling
>+device.
>+
>+2. int state2power(struct thermal_cooling_device *cdev, struct
>+        thermal_zone_device *tz, unsigned long state, u32 *power);
>+@cdev: The `struct thermal_cooling_device` pointer
>+@tz: thermal zone in which we are currently operating
>+@state: A cooling device state
>+@power: pointer in which to store the equivalent power
>+
>+Convert cooling device state @state into power consumption in
>+milliwatts and store it in @power.  It should return 0 on success, -E*
>+on failure.  This is currently used by thermal core to calculate the
>+maximum power that an actor can consume.
>+
>+3. int power2state(struct thermal_cooling_device *cdev, u32 power,
>+	unsigned long *state);
>+@cdev: The `struct thermal_cooling_device` pointer
>+@power: power in milliwatts
>+@state: pointer in which to store the resulting state
>+
>+Calculate a cooling device state that would make the device consume at
>+most @power mW and store it in @state.  It should return 0 on success,
>+-E* on failure.  This is currently used by the thermal core to convert
>+a given power set by the power allocator governor to a state that the
>+cooling device can set.  It is a function because this conversion may
>+depend on external factors that may change so this function should the
>+best conversion given "current circumstances".
>+
>+Cooling device weights
>+----------------------
>+
>+Weights are a mechanism to bias the allocation among cooling
>+devices.  They express the relative power efficiency of different
>+cooling devices.  Higher weight can be used to express higher power
>+efficiency.  Weighting is relative such that if each cooling device
>+has a weight of one they are considered equal.  This is particularly
>+useful in heterogeneous systems where two cooling devices may perform
>+the same kind of compute, but with different efficiency.  For example,
>+a system with two different types of processors.
>+
>+Weights are passed as part of the thermal zone's
>+`thermal_bind_parameters`.
>+
>+Limitations of the power allocator governor
>+===========================================
>+
>+The power allocator governor's PID controller works best if there is a
>+periodic tick.  If you have a driver that calls
>+`thermal_zone_device_update()` (or anything that ends up calling the
>+governor's `throttle()` function) repetitively, the governor response
>+won't be very good.  Note that this is not particular to this
>+governor, step-wise will also misbehave if you call its throttle()
>+faster than the normal thermal framework tick (due to interrupts for
>+example) as it will overreact.
>diff --git a/drivers/thermal/Kconfig b/drivers/thermal/Kconfig
>index af40db0df58e..98a46383b19f 100644
>--- a/drivers/thermal/Kconfig
>+++ b/drivers/thermal/Kconfig
>@@ -71,6 +71,14 @@ config THERMAL_DEFAULT_GOV_USER_SPACE
> 	  Select this if you want to let the user space manage the
> 	  platform thermals.
>
>+config THERMAL_DEFAULT_GOV_POWER_ALLOCATOR
>+	bool "power_allocator"
>+	select THERMAL_GOV_POWER_ALLOCATOR
>+	help
>+	  Select this if you want to control temperature based on
>+	  system and device power allocation. This governor can only
>+	  operate on cooling devices that implement the power API.
>+
> endchoice
>
> config THERMAL_GOV_FAIR_SHARE
>@@ -99,6 +107,13 @@ config THERMAL_GOV_USER_SPACE
> 	help
> 	  Enable this to let the user space manage the platform thermals.
>
>+config THERMAL_GOV_POWER_ALLOCATOR
>+	bool "Power allocator thermal governor"
>+	select THERMAL_POWER_ACTOR
>+	help
>+	  Enable this to manage platform thermals by dynamically
>+	  allocating and limiting power to devices.
>+
> config CPU_THERMAL
> 	bool "generic cpu cooling support"
> 	depends on CPU_FREQ
>diff --git a/drivers/thermal/Makefile b/drivers/thermal/Makefile
>index fa0dc486790f..cd769ab06cbb 100644
>--- a/drivers/thermal/Makefile
>+++ b/drivers/thermal/Makefile
>@@ -14,6 +14,7 @@ thermal_sys-$(CONFIG_THERMAL_GOV_FAIR_SHARE)	+= fair_share.o
> thermal_sys-$(CONFIG_THERMAL_GOV_BANG_BANG)	+= gov_bang_bang.o
> thermal_sys-$(CONFIG_THERMAL_GOV_STEP_WISE)	+= step_wise.o
> thermal_sys-$(CONFIG_THERMAL_GOV_USER_SPACE)	+= user_space.o
>+thermal_sys-$(CONFIG_THERMAL_GOV_POWER_ALLOCATOR)	+= power_allocator.o
>
> # cpufreq cooling
> thermal_sys-$(CONFIG_CPU_THERMAL)	+= cpu_cooling.o
>diff --git a/drivers/thermal/power_allocator.c b/drivers/thermal/power_allocator.c
>new file mode 100644
>index 000000000000..c929143aee67
>--- /dev/null
>+++ b/drivers/thermal/power_allocator.c
>@@ -0,0 +1,478 @@
>+/*
>+ * A power allocator to manage temperature
>+ *
>+ * Copyright (C) 2014 ARM Ltd.
>+ *
>+ * This program is free software; you can redistribute it and/or modify
>+ * it under the terms of the GNU General Public License version 2 as
>+ * published by the Free Software Foundation.
>+ *
>+ * This program is distributed "as is" WITHOUT ANY WARRANTY of any
>+ * kind, whether express or implied; without even the implied warranty
>+ * of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
>+ * GNU General Public License for more details.
>+ */
>+
>+#define pr_fmt(fmt) "Power allocator: " fmt
>+
>+#include <linux/rculist.h>
>+#include <linux/slab.h>
>+#include <linux/thermal.h>
>+
>+#include "thermal_core.h"
>+
>+#define FRAC_BITS 10
>+#define int_to_frac(x) ((x) << FRAC_BITS)
>+#define frac_to_int(x) ((x) >> FRAC_BITS)
>+
>+/**
>+ * mul_frac() - multiply two fixed-point numbers
>+ * @x:	first multiplicand
>+ * @y:	second multiplicand
>+ *
>+ * Return: the result of multiplying two fixed-point numbers.  The
>+ * result is also a fixed-point number.
>+ */
>+static inline s64 mul_frac(s64 x, s64 y)
>+{
>+	return (x * y) >> FRAC_BITS;
>+}
>+
>+enum power_allocator_trip_levels {
>+	TRIP_SWITCH_ON = 0,	/* Switch on PID controller */
>+	TRIP_MAX_DESIRED_TEMPERATURE, /* Temperature we are controlling for */
>+
>+	THERMAL_TRIP_NUM,
>+};

This has to be exported for tz's to respond to the request. See below.

>+
>+/**
>+ * struct power_allocator_params - parameters for the power allocator governor
>+ * @err_integral:	accumulated error in the PID controller.
>+ * @prev_err:	error in the previous iteration of the PID controller.
>+ *		Used to calculate the derivative term.
>+ */
>+struct power_allocator_params {
>+	s64 err_integral;
>+	s32 prev_err;
>+};
>+
>+/**
>+ * pid_controller() - PID controller
>+ * @tz:	thermal zone we are operating in
>+ * @current_temp:	the current temperature in millicelsius
>+ * @control_temp:	the target temperature in millicelsius
>+ * @max_allocatable_power:	maximum allocatable power for this thermal zone
>+ *
>+ * This PID controller increases the available power budget so that the
>+ * temperature of the thermal zone gets as close as possible to
>+ * @control_temp and limits the power if it exceeds it.  k_po is the
>+ * proportional term when we are overshooting, k_pu is the
>+ * proportional term when we are undershooting.  integral_cutoff is a
>+ * threshold below which we stop accumulating the error.  The
>+ * accumulated error is only valid if the requested power will make
>+ * the system warmer.  If the system is mostly idle, there's no point
>+ * in accumulating positive error.
>+ *
>+ * Return: The power budget for the next period.
>+ */
>+static u32 pid_controller(struct thermal_zone_device *tz,
>+			  unsigned long current_temp,
>+			  unsigned long control_temp,
>+			  u32 max_allocatable_power)
>+{
>+	s64 p, i, d, power_range;
>+	s32 err, max_power_frac;
>+	struct power_allocator_params *params = tz->governor_data;
>+
>+	max_power_frac = int_to_frac(max_allocatable_power);
>+
>+	err = ((s32)control_temp - (s32)current_temp);
>+	err = int_to_frac(err);
>+
>+	/* Calculate the proportional term */
>+	p = mul_frac(err < 0 ? tz->tzp->k_po : tz->tzp->k_pu, err);
>+
>+	/*
>+	 * Calculate the integral term
>+	 *
>+	 * if the error is less than cut off allow integration (but
>+	 * the integral is limited to max power)
>+	 */
>+	i = mul_frac(tz->tzp->k_i, params->err_integral);
>+
>+	if (err < int_to_frac(tz->tzp->integral_cutoff)) {
>+		s64 i_next = i + mul_frac(tz->tzp->k_i, err);
>+
>+		if (abs64(i_next) < max_power_frac) {
>+			i = i_next;
>+			params->err_integral += err;
>+		}
>+	}
>+
>+	/*
>+	 * Calculate the derivative term
>+	 *
>+	 * We do err - prev_err, so with a positive k_d, a decreasing
>+	 * error (i.e. driving closer to the line) results in less
>+	 * power being applied, slowing down the controller)
>+	 */
>+	d = mul_frac(tz->tzp->k_d, err - params->prev_err);
>+	params->prev_err = err;
>+
>+	power_range = p + i + d;
>+
>+	/* feed-forward the known sustainable dissipatable power */
>+	power_range = tz->tzp->sustainable_power + frac_to_int(power_range);
>+
>+	return clamp(power_range, (s64)0, (s64)max_allocatable_power);
>+}
>+
>+/**
>+ * divvy_up_power() - divvy the allocated power between the actors
>+ * @req_power:	each actor's requested power
>+ * @max_power:	each actor's maximum available power
>+ * @num_actors:	size of the @req_power, @max_power and @granted_power's array
>+ * @total_req_power: sum of @req_power
>+ * @power_range:	total allocated power
>+ * @granted_power:	output array: each actor's granted power
>+ *
>+ * This function divides the total allocated power (@power_range)
>+ * fairly between the actors.  It first tries to give each actor a
>+ * share of the @power_range according to how much power it requested
>+ * compared to the rest of the actors.  For example, if only one actor
>+ * requests power, then it receives all the @power_range.  If
>+ * three actors each requests 1mW, each receives a third of the
>+ * @power_range.
>+ *
>+ * If any actor received more than their maximum power, then that
>+ * surplus is re-divvied among the actors based on how far they are
>+ * from their respective maximums.
>+ *
>+ * Granted power for each actor is written to @granted_power, which
>+ * should've been allocated by the calling function.
>+ */
>+static void divvy_up_power(u32 *req_power, u32 *max_power, int num_actors,
>+			   u32 total_req_power, u32 power_range,
>+			   u32 *granted_power)
>+{
>+	u32 extra_power, capped_extra_power, extra_actor_power[num_actors];
>+	int i;
>+
>+	/*
>+	 * Prevent division by 0 if none of the actors request power.
>+	 */
>+	if (!total_req_power)
>+		total_req_power = 1;
>+
>+	capped_extra_power = 0;
>+	extra_power = 0;
>+	for (i = 0; i < num_actors; i++) {
>+		u64 req_range = req_power[i] * power_range;
>+
>+		granted_power[i] = div_u64(req_range, total_req_power);
>+
>+		if (granted_power[i] > max_power[i]) {
>+			extra_power += granted_power[i] - max_power[i];
>+			granted_power[i] = max_power[i];
>+		}
>+
>+		extra_actor_power[i] = max_power[i] - granted_power[i];
>+		capped_extra_power += extra_actor_power[i];
>+	}
>+
>+	if (!extra_power)
>+		return;
>+
>+	/*
>+	 * Re-divvy the reclaimed extra among actors based on
>+	 * how far they are from the max
>+	 */
>+	extra_power = min(extra_power, capped_extra_power);
>+	if (capped_extra_power > 0)
>+		for (i = 0; i < num_actors; i++)
>+			granted_power[i] += (extra_actor_power[i] *
>+					extra_power) / capped_extra_power;
>+}
>+
>+static int allocate_power(struct thermal_zone_device *tz,
>+			  unsigned long current_temp,
>+			  unsigned long control_temp)
>+{
>+	struct thermal_instance *instance;
>+	u32 *req_power, *max_power, *granted_power;
>+	u32 total_req_power, max_allocatable_power;
>+	u32 power_range;
>+	int i, num_actors, ret = 0;
>+
>+	mutex_lock(&tz->lock);
>+
>+	num_actors = 0;
>+	list_for_each_entry(instance, &tz->thermal_instances, tz_node)
>+		if ((instance->trip == TRIP_MAX_DESIRED_TEMPERATURE) &&
>+		    cdev_is_power_actor(instance->cdev))
>+			num_actors++;
>+
>+	req_power = devm_kcalloc(&tz->device, num_actors, sizeof(*req_power),
>+				 GFP_KERNEL);
>+	if (!req_power) {
>+		ret = -ENOMEM;
>+		goto unlock;
>+	}
>+
>+	max_power = devm_kcalloc(&tz->device, num_actors, sizeof(*max_power),
>+				 GFP_KERNEL);
>+	if (!max_power) {
>+		ret = -ENOMEM;
>+		goto free_req_power;
>+	}
>+
>+	granted_power = devm_kcalloc(&tz->device, num_actors,
>+				     sizeof(*granted_power), GFP_KERNEL);
>+	if (!granted_power) {
>+		ret = -ENOMEM;
>+		goto free_max_power;
>+	}

You could optimize this allocation by allocating them together and then
using an offset to get max_power and granted_power from req_power.

>+
>+	i = 0;
>+	total_req_power = 0;
>+	max_allocatable_power = 0;
>+
>+	list_for_each_entry(instance, &tz->thermal_instances, tz_node) {
>+		struct thermal_cooling_device *cdev = instance->cdev;
>+
>+		if (instance->trip != TRIP_MAX_DESIRED_TEMPERATURE)
>+			continue;
>+
>+		if (!cdev_is_power_actor(cdev))
>+			continue;
>+
>+		if (cdev->ops->get_requested_power(cdev, tz, &req_power[i]))
>+			continue;
>+
>+		req_power[i] = frac_to_int(instance->weight * req_power[i]);
>+
>+		if (power_actor_get_max_power(cdev, tz, &max_power[i]))
>+			continue;
>+
>+		total_req_power += req_power[i];
>+		max_allocatable_power += max_power[i];
>+
>+		i++;
>+	}
>+
>+	power_range = pid_controller(tz, current_temp, control_temp,
>+				     max_allocatable_power);
>+
>+	divvy_up_power(req_power, max_power, num_actors, total_req_power,
>+		       power_range, granted_power);
>+
>+	i = 0;
>+	list_for_each_entry(instance, &tz->thermal_instances, tz_node) {
>+		if (instance->trip != TRIP_MAX_DESIRED_TEMPERATURE)
>+			continue;
>+
>+		if (!cdev_is_power_actor(instance->cdev))
>+			continue;
>+
>+		power_actor_set_power(instance->cdev, instance,
>+				      granted_power[i]);
>+
>+		i++;
>+	}
>+
>+	devm_kfree(&tz->device, granted_power);
>+free_max_power:
>+	devm_kfree(&tz->device, max_power);
>+free_req_power:
>+	devm_kfree(&tz->device, req_power);
>+unlock:
>+	mutex_unlock(&tz->lock);
>+
>+	return ret;
>+}
>+
>+static int check_trips(struct thermal_zone_device *tz)
>+{
>+	int ret;
>+	enum thermal_trip_type type;
>+
>+	if (tz->trips < THERMAL_TRIP_NUM)
>+		return -EINVAL;
>+
>+	ret = tz->ops->get_trip_type(tz, TRIP_SWITCH_ON, &type);
>+	if (ret)
>+		return ret;

TZ should be able to correctly enumerate the value of this definition in
their driver.

I dont think anymore, this should be a enum thermal_trip_type, but it has to be
generic across governors.


Thanks,
Lina

>+
>+	if (type != THERMAL_TRIP_PASSIVE)
>+		return -EINVAL;
>+
>+	ret = tz->ops->get_trip_type(tz, TRIP_MAX_DESIRED_TEMPERATURE, &type);
>+	if (ret)
>+		return ret;
>+
>+	if (type != THERMAL_TRIP_PASSIVE)
>+		return -EINVAL;
>+
>+	return ret;
>+}
>+
>+static void reset_pid_controller(struct power_allocator_params *params)
>+{
>+	params->err_integral = 0;
>+	params->prev_err = 0;
>+}
>+
>+static void allow_maximum_power(struct thermal_zone_device *tz)
>+{
>+	struct thermal_instance *instance;
>+
>+	list_for_each_entry(instance, &tz->thermal_instances, tz_node) {
>+		if ((instance->trip != TRIP_MAX_DESIRED_TEMPERATURE) ||
>+		    (!cdev_is_power_actor(instance->cdev)))
>+			continue;
>+
>+		instance->target = 0;
>+		instance->cdev->updated = false;
>+		thermal_cdev_update(instance->cdev);
>+	}
>+}
>+
>+/**
>+ * power_allocator_bind() - bind the power_allocator governor to a thermal zone
>+ * @tz:	thermal zone to bind it to
>+ *
>+ * Check that the thermal zone is valid for this governor, that is, it
>+ * has two thermal trips.  If so, initialize the PID controller
>+ * parameters and bind it to the thermal zone.
>+ *
>+ * Return: 0 on success, -EINVAL if the trips were invalid or -ENOMEM
>+ * if we ran out of memory.
>+ */
>+static int power_allocator_bind(struct thermal_zone_device *tz)
>+{
>+	int ret;
>+	struct power_allocator_params *params;
>+	unsigned long switch_on_temp, control_temp;
>+	u32 temperature_threshold;
>+
>+	ret = check_trips(tz);
>+	if (ret) {
>+		dev_err(&tz->device,
>+			"thermal zone %s has wrong trip setup for power allocator\n",
>+			tz->type);
>+		return ret;
>+	}
>+
>+	if (!tz->tzp || !tz->tzp->sustainable_power) {
>+		dev_err(&tz->device,
>+			"power_allocator: missing sustainable_power\n");
>+		return -EINVAL;
>+	}
>+
>+	params = devm_kzalloc(&tz->device, sizeof(*params), GFP_KERNEL);
>+	if (!params)
>+		return -ENOMEM;
>+
>+	ret = tz->ops->get_trip_temp(tz, TRIP_SWITCH_ON, &switch_on_temp);
>+	if (ret)
>+		goto free;
>+
>+	ret = tz->ops->get_trip_temp(tz, TRIP_MAX_DESIRED_TEMPERATURE,
>+				&control_temp);
>+	if (ret)
>+		goto free;
>+
>+	temperature_threshold = control_temp - switch_on_temp;
>+
>+	tz->tzp->k_po = tz->tzp->k_po ?:
>+		int_to_frac(tz->tzp->sustainable_power) / temperature_threshold;
>+	tz->tzp->k_pu = tz->tzp->k_pu ?:
>+		int_to_frac(2 * tz->tzp->sustainable_power) /
>+		temperature_threshold;
>+	tz->tzp->k_i = tz->tzp->k_i ?: int_to_frac(10) / 1000;
>+	/*
>+	 * The default for k_d and integral_cutoff is 0, so we can
>+	 * leave them as they are.
>+	 */
>+
>+	reset_pid_controller(params);
>+
>+	tz->governor_data = params;
>+
>+	return 0;
>+
>+free:
>+	devm_kfree(&tz->device, params);
>+	return ret;
>+}
>+
>+static void power_allocator_unbind(struct thermal_zone_device *tz)
>+{
>+	dev_dbg(&tz->device, "Unbinding from thermal zone %d\n", tz->id);
>+	devm_kfree(&tz->device, tz->governor_data);
>+	tz->governor_data = NULL;
>+}
>+
>+static int power_allocator_throttle(struct thermal_zone_device *tz, int trip)
>+{
>+	int ret;
>+	unsigned long switch_on_temp, control_temp, current_temp;
>+	struct power_allocator_params *params = tz->governor_data;
>+
>+	/*
>+	 * We get called for every trip point but we only need to do
>+	 * our calculations once
>+	 */
>+	if (trip != TRIP_MAX_DESIRED_TEMPERATURE)
>+		return 0;
>+
>+	ret = thermal_zone_get_temp(tz, &current_temp);
>+	if (ret) {
>+		dev_warn(&tz->device, "Failed to get temperature: %d\n", ret);
>+		return ret;
>+	}
>+
>+	ret = tz->ops->get_trip_temp(tz, TRIP_SWITCH_ON, &switch_on_temp);
>+	if (ret) {
>+		dev_warn(&tz->device,
>+			 "Failed to get switch on temperature: %d\n", ret);
>+		return ret;
>+	}
>+
>+	if (current_temp < switch_on_temp) {
>+		tz->passive = 0;
>+		reset_pid_controller(params);
>+		allow_maximum_power(tz);
>+		return 0;
>+	}
>+
>+	tz->passive = 1;
>+
>+	ret = tz->ops->get_trip_temp(tz, TRIP_MAX_DESIRED_TEMPERATURE,
>+				&control_temp);
>+	if (ret) {
>+		dev_warn(&tz->device,
>+			 "Failed to get the maximum desired temperature: %d\n",
>+			 ret);
>+		return ret;
>+	}
>+
>+	return allocate_power(tz, current_temp, control_temp);
>+}
>+
>+static struct thermal_governor thermal_gov_power_allocator = {
>+	.name		= "power_allocator",
>+	.bind_to_tz	= power_allocator_bind,
>+	.unbind_from_tz	= power_allocator_unbind,
>+	.throttle	= power_allocator_throttle,
>+};
>+
>+int thermal_gov_power_allocator_register(void)
>+{
>+	return thermal_register_governor(&thermal_gov_power_allocator);
>+}
>+
>+void thermal_gov_power_allocator_unregister(void)
>+{
>+	thermal_unregister_governor(&thermal_gov_power_allocator);
>+}
>diff --git a/drivers/thermal/thermal_core.c b/drivers/thermal/thermal_core.c
>index a01d4a72bd93..b77b5416929c 100644
>--- a/drivers/thermal/thermal_core.c
>+++ b/drivers/thermal/thermal_core.c
>@@ -1567,7 +1567,7 @@ static void remove_trip_attrs(struct thermal_zone_device *tz)
> struct thermal_zone_device *thermal_zone_device_register(const char *type,
> 	int trips, int mask, void *devdata,
> 	struct thermal_zone_device_ops *ops,
>-	const struct thermal_zone_params *tzp,
>+	struct thermal_zone_params *tzp,
> 	int passive_delay, int polling_delay)
> {
> 	struct thermal_zone_device *tz;
>@@ -1923,7 +1923,11 @@ static int __init thermal_register_governors(void)
> 	if (result)
> 		return result;
>
>-	return thermal_gov_user_space_register();
>+	result = thermal_gov_user_space_register();
>+	if (result)
>+		return result;
>+
>+	return thermal_gov_power_allocator_register();
> }
>
> static void thermal_unregister_governors(void)
>@@ -1932,6 +1936,7 @@ static void thermal_unregister_governors(void)
> 	thermal_gov_fair_share_unregister();
> 	thermal_gov_bang_bang_unregister();
> 	thermal_gov_user_space_unregister();
>+	thermal_gov_power_allocator_unregister();
> }
>
> static int __init thermal_init(void)
>diff --git a/drivers/thermal/thermal_core.h b/drivers/thermal/thermal_core.h
>index 0531c752fbbb..28aa326806eb 100644
>--- a/drivers/thermal/thermal_core.h
>+++ b/drivers/thermal/thermal_core.h
>@@ -85,6 +85,14 @@ static inline int thermal_gov_user_space_register(void) { return 0; }
> static inline void thermal_gov_user_space_unregister(void) {}
> #endif /* CONFIG_THERMAL_GOV_USER_SPACE */
>
>+#ifdef CONFIG_THERMAL_GOV_POWER_ALLOCATOR
>+int thermal_gov_power_allocator_register(void);
>+void thermal_gov_power_allocator_unregister(void);
>+#else
>+static inline int thermal_gov_power_allocator_register(void) { return 0; }
>+static inline void thermal_gov_power_allocator_unregister(void) {}
>+#endif /* CONFIG_THERMAL_GOV_POWER_ALLOCATOR */
>+
> /* device tree support */
> #ifdef CONFIG_THERMAL_OF
> int of_parse_thermal_zones(void);
>diff --git a/include/linux/thermal.h b/include/linux/thermal.h
>index 288ac6fd743d..b42f790bb23c 100644
>--- a/include/linux/thermal.h
>+++ b/include/linux/thermal.h
>@@ -56,6 +56,8 @@
> #define DEFAULT_THERMAL_GOVERNOR       "fair_share"
> #elif defined(CONFIG_THERMAL_DEFAULT_GOV_USER_SPACE)
> #define DEFAULT_THERMAL_GOVERNOR       "user_space"
>+#elif defined(CONFIG_THERMAL_DEFAULT_GOV_POWER_ALLOCATOR)
>+#define DEFAULT_THERMAL_GOVERNOR       "power_allocator"
> #endif
>
> struct thermal_zone_device;
>@@ -151,8 +153,7 @@ struct thermal_attr {
>  * @devdata:	private pointer for device private data
>  * @trips:	number of trip points the thermal zone supports
>  * @passive_delay:	number of milliseconds to wait between polls when
>- *			performing passive cooling.  Currenty only used by the
>- *			step-wise governor
>+ *			performing passive cooling.
>  * @polling_delay:	number of milliseconds to wait between polls when
>  *			checking whether trip points have been crossed (0 for
>  *			interrupt driven systems)
>@@ -162,7 +163,6 @@ struct thermal_attr {
>  * @last_temperature:	previous temperature read
>  * @emul_temperature:	emulated temperature when using CONFIG_THERMAL_EMULATION
>  * @passive:		1 if you've crossed a passive trip point, 0 otherwise.
>- *			Currenty only used by the step-wise governor.
>  * @forced_passive:	If > 0, temperature at which to switch on all ACPI
>  *			processor cooling devices.  Currently only used by the
>  *			step-wise governor.
>@@ -194,7 +194,7 @@ struct thermal_zone_device {
> 	int passive;
> 	unsigned int forced_passive;
> 	struct thermal_zone_device_ops *ops;
>-	const struct thermal_zone_params *tzp;
>+	struct thermal_zone_params *tzp;
> 	struct thermal_governor *governor;
> 	void *governor_data;
> 	struct list_head thermal_instances;
>@@ -269,6 +269,33 @@ struct thermal_zone_params {
>
> 	int num_tbps;	/* Number of tbp entries */
> 	struct thermal_bind_params *tbp;
>+
>+	/*
>+	 * Sustainable power (heat) that this thermal zone can dissipate in
>+	 * mW
>+	 */
>+	u32 sustainable_power;
>+
>+	/*
>+	 * Proportional parameter of the PID controller when
>+	 * overshooting (i.e., when temperature is below the target)
>+	 */
>+	s32 k_po;
>+
>+	/*
>+	 * Proportional parameter of the PID controller when
>+	 * undershooting
>+	 */
>+	s32 k_pu;
>+
>+	/* Integral parameter of the PID controller */
>+	s32 k_i;
>+
>+	/* Derivative parameter of the PID controller */
>+	s32 k_d;
>+
>+	/* threshold below which the error is no longer accumulated */
>+	s32 integral_cutoff;
> };
>
> struct thermal_genl_event {
>@@ -343,7 +370,7 @@ int power_actor_set_power(struct thermal_cooling_device *,
> 			  struct thermal_instance *, u32);
> struct thermal_zone_device *thermal_zone_device_register(const char *, int, int,
> 		void *, struct thermal_zone_device_ops *,
>-		const struct thermal_zone_params *, int, int);
>+		struct thermal_zone_params *, int, int);
> void thermal_zone_device_unregister(struct thermal_zone_device *);
>
> int thermal_zone_bind_cooling_device(struct thermal_zone_device *, int,
>-- 
>1.9.1
>
>--
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Re: [PATCH v1 4/7] thermal: introduce the Power Allocator governor

[Javi Merino]

On Mon, Feb 02, 2015 at 11:51:20PM +0000, Lina Iyer wrote:
> On Wed, Jan 28 2015 at 14:42 -0700, Javi Merino wrote:
> >The power allocator governor is a thermal governor that controls system
> >and device power allocation to control temperature.  Conceptually, the
> >implementation divides the sustainable power of a thermal zone among
> >all the heat sources in that zone.
> >
> >This governor relies on "power actors", entities that represent heat
> >sources.  They can report current and maximum power consumption and
> >can set a given maximum power consumption, usually via a cooling
> >device.
> >
> >The governor uses a Proportional Integral Derivative (PID) controller
> >driven by the temperature of the thermal zone.  The output of the
> >controller is a power budget that is then allocated to each power
> >actor that can have bearing on the temperature we are trying to
> >control.  It decides how much power to give each cooling device based
> >on the performance they are requesting.  The PID controller ensures
> >that the total power budget does not exceed the control temperature.
> >
> >Cc: Zhang Rui <rui.zhang@intel.com>
> >Cc: Eduardo Valentin <edubezval@gmail.com>
> >Signed-off-by: Punit Agrawal <punit.agrawal@arm.com>
> >Signed-off-by: Javi Merino <javi.merino@arm.com>
> >---
> > Documentation/thermal/power_allocator.txt | 241 +++++++++++++++
> > drivers/thermal/Kconfig                   |  15 +
> > drivers/thermal/Makefile                  |   1 +
> > drivers/thermal/power_allocator.c         | 478 ++++++++++++++++++++++++++++++
> > drivers/thermal/thermal_core.c            |   9 +-
> > drivers/thermal/thermal_core.h            |   8 +
> > include/linux/thermal.h                   |  37 ++-
> > 7 files changed, 782 insertions(+), 7 deletions(-)
> > create mode 100644 Documentation/thermal/power_allocator.txt
> > create mode 100644 drivers/thermal/power_allocator.c
> >
[...]
> >diff --git a/drivers/thermal/power_allocator.c b/drivers/thermal/power_allocator.c
> >new file mode 100644
> >index 000000000000..c929143aee67
> >--- /dev/null
> >+++ b/drivers/thermal/power_allocator.c
> >@@ -0,0 +1,478 @@
> >+/*
> >+ * A power allocator to manage temperature
> >+ *
> >+ * Copyright (C) 2014 ARM Ltd.
> >+ *
> >+ * This program is free software; you can redistribute it and/or modify
> >+ * it under the terms of the GNU General Public License version 2 as
> >+ * published by the Free Software Foundation.
> >+ *
> >+ * This program is distributed "as is" WITHOUT ANY WARRANTY of any
> >+ * kind, whether express or implied; without even the implied warranty
> >+ * of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
> >+ * GNU General Public License for more details.
> >+ */
> >+
> >+#define pr_fmt(fmt) "Power allocator: " fmt
> >+
> >+#include <linux/rculist.h>
> >+#include <linux/slab.h>
> >+#include <linux/thermal.h>
> >+
> >+#include "thermal_core.h"
> >+
> >+#define FRAC_BITS 10
> >+#define int_to_frac(x) ((x) << FRAC_BITS)
> >+#define frac_to_int(x) ((x) >> FRAC_BITS)
> >+
> >+/**
> >+ * mul_frac() - multiply two fixed-point numbers
> >+ * @x:        first multiplicand
> >+ * @y:        second multiplicand
> >+ *
> >+ * Return: the result of multiplying two fixed-point numbers.  The
> >+ * result is also a fixed-point number.
> >+ */
> >+static inline s64 mul_frac(s64 x, s64 y)
> >+{
> >+      return (x * y) >> FRAC_BITS;
> >+}
> >+
> >+enum power_allocator_trip_levels {
> >+      TRIP_SWITCH_ON = 0,     /* Switch on PID controller */
> >+      TRIP_MAX_DESIRED_TEMPERATURE, /* Temperature we are controlling for */
> >+
> >+      THERMAL_TRIP_NUM,
> >+};
> 
> This has to be exported for tz's to respond to the request. See below.
> 
> >+
> >+/**
> >+ * struct power_allocator_params - parameters for the power allocator governor
> >+ * @err_integral:     accumulated error in the PID controller.
> >+ * @prev_err: error in the previous iteration of the PID controller.
> >+ *            Used to calculate the derivative term.
> >+ */
> >+struct power_allocator_params {
> >+      s64 err_integral;
> >+      s32 prev_err;
> >+};
> >+
> >+/**
> >+ * pid_controller() - PID controller
> >+ * @tz:       thermal zone we are operating in
> >+ * @current_temp:     the current temperature in millicelsius
> >+ * @control_temp:     the target temperature in millicelsius
> >+ * @max_allocatable_power:    maximum allocatable power for this thermal zone
> >+ *
> >+ * This PID controller increases the available power budget so that the
> >+ * temperature of the thermal zone gets as close as possible to
> >+ * @control_temp and limits the power if it exceeds it.  k_po is the
> >+ * proportional term when we are overshooting, k_pu is the
> >+ * proportional term when we are undershooting.  integral_cutoff is a
> >+ * threshold below which we stop accumulating the error.  The
> >+ * accumulated error is only valid if the requested power will make
> >+ * the system warmer.  If the system is mostly idle, there's no point
> >+ * in accumulating positive error.
> >+ *
> >+ * Return: The power budget for the next period.
> >+ */
> >+static u32 pid_controller(struct thermal_zone_device *tz,
> >+                        unsigned long current_temp,
> >+                        unsigned long control_temp,
> >+                        u32 max_allocatable_power)
> >+{
> >+      s64 p, i, d, power_range;
> >+      s32 err, max_power_frac;
> >+      struct power_allocator_params *params = tz->governor_data;
> >+
> >+      max_power_frac = int_to_frac(max_allocatable_power);
> >+
> >+      err = ((s32)control_temp - (s32)current_temp);
> >+      err = int_to_frac(err);
> >+
> >+      /* Calculate the proportional term */
> >+      p = mul_frac(err < 0 ? tz->tzp->k_po : tz->tzp->k_pu, err);
> >+
> >+      /*
> >+       * Calculate the integral term
> >+       *
> >+       * if the error is less than cut off allow integration (but
> >+       * the integral is limited to max power)
> >+       */
> >+      i = mul_frac(tz->tzp->k_i, params->err_integral);
> >+
> >+      if (err < int_to_frac(tz->tzp->integral_cutoff)) {
> >+              s64 i_next = i + mul_frac(tz->tzp->k_i, err);
> >+
> >+              if (abs64(i_next) < max_power_frac) {
> >+                      i = i_next;
> >+                      params->err_integral += err;
> >+              }
> >+      }
> >+
> >+      /*
> >+       * Calculate the derivative term
> >+       *
> >+       * We do err - prev_err, so with a positive k_d, a decreasing
> >+       * error (i.e. driving closer to the line) results in less
> >+       * power being applied, slowing down the controller)
> >+       */
> >+      d = mul_frac(tz->tzp->k_d, err - params->prev_err);
> >+      params->prev_err = err;
> >+
> >+      power_range = p + i + d;
> >+
> >+      /* feed-forward the known sustainable dissipatable power */
> >+      power_range = tz->tzp->sustainable_power + frac_to_int(power_range);
> >+
> >+      return clamp(power_range, (s64)0, (s64)max_allocatable_power);
> >+}
> >+
> >+/**
> >+ * divvy_up_power() - divvy the allocated power between the actors
> >+ * @req_power:        each actor's requested power
> >+ * @max_power:        each actor's maximum available power
> >+ * @num_actors:       size of the @req_power, @max_power and @granted_power's array
> >+ * @total_req_power: sum of @req_power
> >+ * @power_range:      total allocated power
> >+ * @granted_power:    output array: each actor's granted power
> >+ *
> >+ * This function divides the total allocated power (@power_range)
> >+ * fairly between the actors.  It first tries to give each actor a
> >+ * share of the @power_range according to how much power it requested
> >+ * compared to the rest of the actors.  For example, if only one actor
> >+ * requests power, then it receives all the @power_range.  If
> >+ * three actors each requests 1mW, each receives a third of the
> >+ * @power_range.
> >+ *
> >+ * If any actor received more than their maximum power, then that
> >+ * surplus is re-divvied among the actors based on how far they are
> >+ * from their respective maximums.
> >+ *
> >+ * Granted power for each actor is written to @granted_power, which
> >+ * should've been allocated by the calling function.
> >+ */
> >+static void divvy_up_power(u32 *req_power, u32 *max_power, int num_actors,
> >+                         u32 total_req_power, u32 power_range,
> >+                         u32 *granted_power)
> >+{
> >+      u32 extra_power, capped_extra_power, extra_actor_power[num_actors];
> >+      int i;
> >+
> >+      /*
> >+       * Prevent division by 0 if none of the actors request power.
> >+       */
> >+      if (!total_req_power)
> >+              total_req_power = 1;
> >+
> >+      capped_extra_power = 0;
> >+      extra_power = 0;
> >+      for (i = 0; i < num_actors; i++) {
> >+              u64 req_range = req_power[i] * power_range;
> >+
> >+              granted_power[i] = div_u64(req_range, total_req_power);
> >+
> >+              if (granted_power[i] > max_power[i]) {
> >+                      extra_power += granted_power[i] - max_power[i];
> >+                      granted_power[i] = max_power[i];
> >+              }
> >+
> >+              extra_actor_power[i] = max_power[i] - granted_power[i];
> >+              capped_extra_power += extra_actor_power[i];
> >+      }
> >+
> >+      if (!extra_power)
> >+              return;
> >+
> >+      /*
> >+       * Re-divvy the reclaimed extra among actors based on
> >+       * how far they are from the max
> >+       */
> >+      extra_power = min(extra_power, capped_extra_power);
> >+      if (capped_extra_power > 0)
> >+              for (i = 0; i < num_actors; i++)
> >+                      granted_power[i] += (extra_actor_power[i] *
> >+                                      extra_power) / capped_extra_power;
> >+}
> >+
> >+static int allocate_power(struct thermal_zone_device *tz,
> >+                        unsigned long current_temp,
> >+                        unsigned long control_temp)
> >+{
> >+      struct thermal_instance *instance;
> >+      u32 *req_power, *max_power, *granted_power;
> >+      u32 total_req_power, max_allocatable_power;
> >+      u32 power_range;
> >+      int i, num_actors, ret = 0;
> >+
> >+      mutex_lock(&tz->lock);
> >+
> >+      num_actors = 0;
> >+      list_for_each_entry(instance, &tz->thermal_instances, tz_node)
> >+              if ((instance->trip == TRIP_MAX_DESIRED_TEMPERATURE) &&
> >+                  cdev_is_power_actor(instance->cdev))
> >+                      num_actors++;
> >+
> >+      req_power = devm_kcalloc(&tz->device, num_actors, sizeof(*req_power),
> >+                               GFP_KERNEL);
> >+      if (!req_power) {
> >+              ret = -ENOMEM;
> >+              goto unlock;
> >+      }
> >+
> >+      max_power = devm_kcalloc(&tz->device, num_actors, sizeof(*max_power),
> >+                               GFP_KERNEL);
> >+      if (!max_power) {
> >+              ret = -ENOMEM;
> >+              goto free_req_power;
> >+      }
> >+
> >+      granted_power = devm_kcalloc(&tz->device, num_actors,
> >+                                   sizeof(*granted_power), GFP_KERNEL);
> >+      if (!granted_power) {
> >+              ret = -ENOMEM;
> >+              goto free_max_power;
> >+      }
> 
> You could optimize this allocation by allocating them together and then
> using an offset to get max_power and granted_power from req_power.

Makes sense, I've changed it to: 

	/*
	 * We need to allocate three arrays of the same size:
	 * req_power, max_power and granted_power.  They are going to
	 * be needed until this function returns.  Allocate them all
	 * in one go to simplify the allocation and deallocation
	 * logic.
	 */
	BUILD_BUG_ON(sizeof(*req_power) != sizeof(*max_power));
	BUILD_BUG_ON(sizeof(*req_power) != sizeof(*granted_power));
	req_power = devm_kcalloc(&tz->device, num_actors * 3,
				 sizeof(*req_power), GFP_KERNEL);
	if (!req_power) {
		ret = -ENOMEM;
		goto unlock;
	}

	max_power = &req_power[num_actors];
	granted_power = &req_power[2 * num_actors];

> >+
> >+      i = 0;
> >+      total_req_power = 0;
> >+      max_allocatable_power = 0;
> >+
> >+      list_for_each_entry(instance, &tz->thermal_instances, tz_node) {
> >+              struct thermal_cooling_device *cdev = instance->cdev;
> >+
> >+              if (instance->trip != TRIP_MAX_DESIRED_TEMPERATURE)
> >+                      continue;
> >+
> >+              if (!cdev_is_power_actor(cdev))
> >+                      continue;
> >+
> >+              if (cdev->ops->get_requested_power(cdev, tz, &req_power[i]))
> >+                      continue;
> >+
> >+              req_power[i] = frac_to_int(instance->weight * req_power[i]);
> >+
> >+              if (power_actor_get_max_power(cdev, tz, &max_power[i]))
> >+                      continue;
> >+
> >+              total_req_power += req_power[i];
> >+              max_allocatable_power += max_power[i];
> >+
> >+              i++;
> >+      }
> >+
> >+      power_range = pid_controller(tz, current_temp, control_temp,
> >+                                   max_allocatable_power);
> >+
> >+      divvy_up_power(req_power, max_power, num_actors, total_req_power,
> >+                     power_range, granted_power);
> >+
> >+      i = 0;
> >+      list_for_each_entry(instance, &tz->thermal_instances, tz_node) {
> >+              if (instance->trip != TRIP_MAX_DESIRED_TEMPERATURE)
> >+                      continue;
> >+
> >+              if (!cdev_is_power_actor(instance->cdev))
> >+                      continue;
> >+
> >+              power_actor_set_power(instance->cdev, instance,
> >+                                    granted_power[i]);
> >+
> >+              i++;
> >+      }
> >+
> >+      devm_kfree(&tz->device, granted_power);
> >+free_max_power:
> >+      devm_kfree(&tz->device, max_power);
> >+free_req_power:
> >+      devm_kfree(&tz->device, req_power);
> >+unlock:
> >+      mutex_unlock(&tz->lock);
> >+
> >+      return ret;
> >+}
> >+
> >+static int check_trips(struct thermal_zone_device *tz)
> >+{
> >+      int ret;
> >+      enum thermal_trip_type type;
> >+
> >+      if (tz->trips < THERMAL_TRIP_NUM)
> >+              return -EINVAL;
> >+
> >+      ret = tz->ops->get_trip_type(tz, TRIP_SWITCH_ON, &type);
> >+      if (ret)
> >+              return ret;
> 
> TZ should be able to correctly enumerate the value of this definition in
> their driver.

Right, drivers can use this enum so it should be in a header that they
can include.  I've moved the "enum power_allocator_trip_levels"
definition to thermal.h .  I considered drivers/thermal/thermal_core.h
but no drivers include that so it's probably not the right place
(others can correct me if I'm wrong).

Cheers,
Javi

> I dont think anymore, this should be a enum thermal_trip_type, but it has to be
> generic across governors.
> 
> 
> Thanks,
> Lina

Re: [PATCH v1 4/7] thermal: introduce the Power Allocator governor

[Eduardo Valentin]

[-- Attachment #1: Type: text/plain, Size: 17245 bytes --]

On Tue, Feb 03, 2015 at 01:03:37PM +0000, Javi Merino wrote:
> On Mon, Feb 02, 2015 at 11:51:20PM +0000, Lina Iyer wrote:
> > On Wed, Jan 28 2015 at 14:42 -0700, Javi Merino wrote:
> > >The power allocator governor is a thermal governor that controls system
> > >and device power allocation to control temperature.  Conceptually, the
> > >implementation divides the sustainable power of a thermal zone among
> > >all the heat sources in that zone.
> > >
> > >This governor relies on "power actors", entities that represent heat
> > >sources.  They can report current and maximum power consumption and
> > >can set a given maximum power consumption, usually via a cooling
> > >device.
> > >
> > >The governor uses a Proportional Integral Derivative (PID) controller
> > >driven by the temperature of the thermal zone.  The output of the
> > >controller is a power budget that is then allocated to each power
> > >actor that can have bearing on the temperature we are trying to
> > >control.  It decides how much power to give each cooling device based
> > >on the performance they are requesting.  The PID controller ensures
> > >that the total power budget does not exceed the control temperature.
> > >
> > >Cc: Zhang Rui <rui.zhang@intel.com>
> > >Cc: Eduardo Valentin <edubezval@gmail.com>
> > >Signed-off-by: Punit Agrawal <punit.agrawal@arm.com>
> > >Signed-off-by: Javi Merino <javi.merino@arm.com>
> > >---
> > > Documentation/thermal/power_allocator.txt | 241 +++++++++++++++
> > > drivers/thermal/Kconfig                   |  15 +
> > > drivers/thermal/Makefile                  |   1 +
> > > drivers/thermal/power_allocator.c         | 478 ++++++++++++++++++++++++++++++
> > > drivers/thermal/thermal_core.c            |   9 +-
> > > drivers/thermal/thermal_core.h            |   8 +
> > > include/linux/thermal.h                   |  37 ++-
> > > 7 files changed, 782 insertions(+), 7 deletions(-)
> > > create mode 100644 Documentation/thermal/power_allocator.txt
> > > create mode 100644 drivers/thermal/power_allocator.c
> > >
> [...]
> > >diff --git a/drivers/thermal/power_allocator.c b/drivers/thermal/power_allocator.c
> > >new file mode 100644
> > >index 000000000000..c929143aee67
> > >--- /dev/null
> > >+++ b/drivers/thermal/power_allocator.c
> > >@@ -0,0 +1,478 @@
> > >+/*
> > >+ * A power allocator to manage temperature
> > >+ *
> > >+ * Copyright (C) 2014 ARM Ltd.
> > >+ *
> > >+ * This program is free software; you can redistribute it and/or modify
> > >+ * it under the terms of the GNU General Public License version 2 as
> > >+ * published by the Free Software Foundation.
> > >+ *
> > >+ * This program is distributed "as is" WITHOUT ANY WARRANTY of any
> > >+ * kind, whether express or implied; without even the implied warranty
> > >+ * of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
> > >+ * GNU General Public License for more details.
> > >+ */
> > >+
> > >+#define pr_fmt(fmt) "Power allocator: " fmt
> > >+
> > >+#include <linux/rculist.h>
> > >+#include <linux/slab.h>
> > >+#include <linux/thermal.h>
> > >+
> > >+#include "thermal_core.h"
> > >+
> > >+#define FRAC_BITS 10
> > >+#define int_to_frac(x) ((x) << FRAC_BITS)
> > >+#define frac_to_int(x) ((x) >> FRAC_BITS)
> > >+
> > >+/**
> > >+ * mul_frac() - multiply two fixed-point numbers
> > >+ * @x:        first multiplicand
> > >+ * @y:        second multiplicand
> > >+ *
> > >+ * Return: the result of multiplying two fixed-point numbers.  The
> > >+ * result is also a fixed-point number.
> > >+ */
> > >+static inline s64 mul_frac(s64 x, s64 y)
> > >+{
> > >+      return (x * y) >> FRAC_BITS;
> > >+}
> > >+
> > >+enum power_allocator_trip_levels {
> > >+      TRIP_SWITCH_ON = 0,     /* Switch on PID controller */
> > >+      TRIP_MAX_DESIRED_TEMPERATURE, /* Temperature we are controlling for */
> > >+
> > >+      THERMAL_TRIP_NUM,
> > >+};
> > 
> > This has to be exported for tz's to respond to the request. See below.
> > 
> > >+
> > >+/**
> > >+ * struct power_allocator_params - parameters for the power allocator governor
> > >+ * @err_integral:     accumulated error in the PID controller.
> > >+ * @prev_err: error in the previous iteration of the PID controller.
> > >+ *            Used to calculate the derivative term.
> > >+ */
> > >+struct power_allocator_params {
> > >+      s64 err_integral;
> > >+      s32 prev_err;
> > >+};
> > >+
> > >+/**
> > >+ * pid_controller() - PID controller
> > >+ * @tz:       thermal zone we are operating in
> > >+ * @current_temp:     the current temperature in millicelsius
> > >+ * @control_temp:     the target temperature in millicelsius
> > >+ * @max_allocatable_power:    maximum allocatable power for this thermal zone
> > >+ *
> > >+ * This PID controller increases the available power budget so that the
> > >+ * temperature of the thermal zone gets as close as possible to
> > >+ * @control_temp and limits the power if it exceeds it.  k_po is the
> > >+ * proportional term when we are overshooting, k_pu is the
> > >+ * proportional term when we are undershooting.  integral_cutoff is a
> > >+ * threshold below which we stop accumulating the error.  The
> > >+ * accumulated error is only valid if the requested power will make
> > >+ * the system warmer.  If the system is mostly idle, there's no point
> > >+ * in accumulating positive error.
> > >+ *
> > >+ * Return: The power budget for the next period.
> > >+ */
> > >+static u32 pid_controller(struct thermal_zone_device *tz,
> > >+                        unsigned long current_temp,
> > >+                        unsigned long control_temp,
> > >+                        u32 max_allocatable_power)
> > >+{
> > >+      s64 p, i, d, power_range;
> > >+      s32 err, max_power_frac;
> > >+      struct power_allocator_params *params = tz->governor_data;
> > >+
> > >+      max_power_frac = int_to_frac(max_allocatable_power);
> > >+
> > >+      err = ((s32)control_temp - (s32)current_temp);
> > >+      err = int_to_frac(err);
> > >+
> > >+      /* Calculate the proportional term */
> > >+      p = mul_frac(err < 0 ? tz->tzp->k_po : tz->tzp->k_pu, err);
> > >+
> > >+      /*
> > >+       * Calculate the integral term
> > >+       *
> > >+       * if the error is less than cut off allow integration (but
> > >+       * the integral is limited to max power)
> > >+       */
> > >+      i = mul_frac(tz->tzp->k_i, params->err_integral);
> > >+
> > >+      if (err < int_to_frac(tz->tzp->integral_cutoff)) {
> > >+              s64 i_next = i + mul_frac(tz->tzp->k_i, err);
> > >+
> > >+              if (abs64(i_next) < max_power_frac) {
> > >+                      i = i_next;
> > >+                      params->err_integral += err;
> > >+              }
> > >+      }
> > >+
> > >+      /*
> > >+       * Calculate the derivative term
> > >+       *
> > >+       * We do err - prev_err, so with a positive k_d, a decreasing
> > >+       * error (i.e. driving closer to the line) results in less
> > >+       * power being applied, slowing down the controller)
> > >+       */
> > >+      d = mul_frac(tz->tzp->k_d, err - params->prev_err);
> > >+      params->prev_err = err;
> > >+
> > >+      power_range = p + i + d;
> > >+
> > >+      /* feed-forward the known sustainable dissipatable power */
> > >+      power_range = tz->tzp->sustainable_power + frac_to_int(power_range);
> > >+
> > >+      return clamp(power_range, (s64)0, (s64)max_allocatable_power);
> > >+}
> > >+
> > >+/**
> > >+ * divvy_up_power() - divvy the allocated power between the actors
> > >+ * @req_power:        each actor's requested power
> > >+ * @max_power:        each actor's maximum available power
> > >+ * @num_actors:       size of the @req_power, @max_power and @granted_power's array
> > >+ * @total_req_power: sum of @req_power
> > >+ * @power_range:      total allocated power
> > >+ * @granted_power:    output array: each actor's granted power
> > >+ *
> > >+ * This function divides the total allocated power (@power_range)
> > >+ * fairly between the actors.  It first tries to give each actor a
> > >+ * share of the @power_range according to how much power it requested
> > >+ * compared to the rest of the actors.  For example, if only one actor
> > >+ * requests power, then it receives all the @power_range.  If
> > >+ * three actors each requests 1mW, each receives a third of the
> > >+ * @power_range.
> > >+ *
> > >+ * If any actor received more than their maximum power, then that
> > >+ * surplus is re-divvied among the actors based on how far they are
> > >+ * from their respective maximums.
> > >+ *
> > >+ * Granted power for each actor is written to @granted_power, which
> > >+ * should've been allocated by the calling function.
> > >+ */
> > >+static void divvy_up_power(u32 *req_power, u32 *max_power, int num_actors,
> > >+                         u32 total_req_power, u32 power_range,
> > >+                         u32 *granted_power)
> > >+{
> > >+      u32 extra_power, capped_extra_power, extra_actor_power[num_actors];
> > >+      int i;
> > >+
> > >+      /*
> > >+       * Prevent division by 0 if none of the actors request power.
> > >+       */
> > >+      if (!total_req_power)
> > >+              total_req_power = 1;
> > >+
> > >+      capped_extra_power = 0;
> > >+      extra_power = 0;
> > >+      for (i = 0; i < num_actors; i++) {
> > >+              u64 req_range = req_power[i] * power_range;
> > >+
> > >+              granted_power[i] = div_u64(req_range, total_req_power);
> > >+
> > >+              if (granted_power[i] > max_power[i]) {
> > >+                      extra_power += granted_power[i] - max_power[i];
> > >+                      granted_power[i] = max_power[i];
> > >+              }
> > >+
> > >+              extra_actor_power[i] = max_power[i] - granted_power[i];
> > >+              capped_extra_power += extra_actor_power[i];
> > >+      }
> > >+
> > >+      if (!extra_power)
> > >+              return;
> > >+
> > >+      /*
> > >+       * Re-divvy the reclaimed extra among actors based on
> > >+       * how far they are from the max
> > >+       */
> > >+      extra_power = min(extra_power, capped_extra_power);
> > >+      if (capped_extra_power > 0)
> > >+              for (i = 0; i < num_actors; i++)
> > >+                      granted_power[i] += (extra_actor_power[i] *
> > >+                                      extra_power) / capped_extra_power;
> > >+}
> > >+
> > >+static int allocate_power(struct thermal_zone_device *tz,
> > >+                        unsigned long current_temp,
> > >+                        unsigned long control_temp)
> > >+{
> > >+      struct thermal_instance *instance;
> > >+      u32 *req_power, *max_power, *granted_power;
> > >+      u32 total_req_power, max_allocatable_power;
> > >+      u32 power_range;
> > >+      int i, num_actors, ret = 0;
> > >+
> > >+      mutex_lock(&tz->lock);
> > >+
> > >+      num_actors = 0;
> > >+      list_for_each_entry(instance, &tz->thermal_instances, tz_node)
> > >+              if ((instance->trip == TRIP_MAX_DESIRED_TEMPERATURE) &&
> > >+                  cdev_is_power_actor(instance->cdev))
> > >+                      num_actors++;
> > >+
> > >+      req_power = devm_kcalloc(&tz->device, num_actors, sizeof(*req_power),
> > >+                               GFP_KERNEL);
> > >+      if (!req_power) {
> > >+              ret = -ENOMEM;
> > >+              goto unlock;
> > >+      }
> > >+
> > >+      max_power = devm_kcalloc(&tz->device, num_actors, sizeof(*max_power),
> > >+                               GFP_KERNEL);
> > >+      if (!max_power) {
> > >+              ret = -ENOMEM;
> > >+              goto free_req_power;
> > >+      }
> > >+
> > >+      granted_power = devm_kcalloc(&tz->device, num_actors,
> > >+                                   sizeof(*granted_power), GFP_KERNEL);
> > >+      if (!granted_power) {
> > >+              ret = -ENOMEM;
> > >+              goto free_max_power;
> > >+      }
> > 
> > You could optimize this allocation by allocating them together and then
> > using an offset to get max_power and granted_power from req_power.
> 
> Makes sense, I've changed it to: 
> 
> 	/*
> 	 * We need to allocate three arrays of the same size:
> 	 * req_power, max_power and granted_power.  They are going to
> 	 * be needed until this function returns.  Allocate them all
> 	 * in one go to simplify the allocation and deallocation
> 	 * logic.
> 	 */
> 	BUILD_BUG_ON(sizeof(*req_power) != sizeof(*max_power));
> 	BUILD_BUG_ON(sizeof(*req_power) != sizeof(*granted_power));
> 	req_power = devm_kcalloc(&tz->device, num_actors * 3,
> 				 sizeof(*req_power), GFP_KERNEL);
> 	if (!req_power) {
> 		ret = -ENOMEM;
> 		goto unlock;
> 	}
> 
> 	max_power = &req_power[num_actors];
> 	granted_power = &req_power[2 * num_actors];
> 
> > >+
> > >+      i = 0;
> > >+      total_req_power = 0;
> > >+      max_allocatable_power = 0;
> > >+
> > >+      list_for_each_entry(instance, &tz->thermal_instances, tz_node) {
> > >+              struct thermal_cooling_device *cdev = instance->cdev;
> > >+
> > >+              if (instance->trip != TRIP_MAX_DESIRED_TEMPERATURE)
> > >+                      continue;
> > >+
> > >+              if (!cdev_is_power_actor(cdev))
> > >+                      continue;
> > >+
> > >+              if (cdev->ops->get_requested_power(cdev, tz, &req_power[i]))
> > >+                      continue;
> > >+
> > >+              req_power[i] = frac_to_int(instance->weight * req_power[i]);
> > >+
> > >+              if (power_actor_get_max_power(cdev, tz, &max_power[i]))
> > >+                      continue;
> > >+
> > >+              total_req_power += req_power[i];
> > >+              max_allocatable_power += max_power[i];
> > >+
> > >+              i++;
> > >+      }
> > >+
> > >+      power_range = pid_controller(tz, current_temp, control_temp,
> > >+                                   max_allocatable_power);
> > >+
> > >+      divvy_up_power(req_power, max_power, num_actors, total_req_power,
> > >+                     power_range, granted_power);
> > >+
> > >+      i = 0;
> > >+      list_for_each_entry(instance, &tz->thermal_instances, tz_node) {
> > >+              if (instance->trip != TRIP_MAX_DESIRED_TEMPERATURE)
> > >+                      continue;
> > >+
> > >+              if (!cdev_is_power_actor(instance->cdev))
> > >+                      continue;
> > >+
> > >+              power_actor_set_power(instance->cdev, instance,
> > >+                                    granted_power[i]);
> > >+
> > >+              i++;
> > >+      }
> > >+
> > >+      devm_kfree(&tz->device, granted_power);
> > >+free_max_power:
> > >+      devm_kfree(&tz->device, max_power);
> > >+free_req_power:
> > >+      devm_kfree(&tz->device, req_power);
> > >+unlock:
> > >+      mutex_unlock(&tz->lock);
> > >+
> > >+      return ret;
> > >+}
> > >+
> > >+static int check_trips(struct thermal_zone_device *tz)
> > >+{
> > >+      int ret;
> > >+      enum thermal_trip_type type;
> > >+
> > >+      if (tz->trips < THERMAL_TRIP_NUM)
> > >+              return -EINVAL;
> > >+
> > >+      ret = tz->ops->get_trip_type(tz, TRIP_SWITCH_ON, &type);
> > >+      if (ret)
> > >+              return ret;
> > 
> > TZ should be able to correctly enumerate the value of this definition in
> > their driver.
> 
> Right, drivers can use this enum so it should be in a header that they
> can include.  I've moved the "enum power_allocator_trip_levels"
> definition to thermal.h .  I considered drivers/thermal/thermal_core.h
> but no drivers include that so it's probably not the right place
> (others can correct me if I'm wrong).

Well, I am not convinced drivers really need to be aware of these trip
types. Which kind of drivers are we talking? Thermal zone drivers?
cooling device drivers?

Lina, do you have an existing driver (it can be yet to be posted) that
would required using these types? To my understanding, these are simply
for the governor internal control, drivers do not really need to understand
the difference from one to another.

The purpose of the .bind_to_tz callback is exactly to verify if the
driver has added the required info into the thermal zone. Including the
trip setup.

Besides, the existing exposed trip types are sufficient, given that this
series is in a working state. Unless we have a valid use case to change
/ add trip types and expose them to driver, I would prefer to keep this
simple.

Side note, drivers/thermal/thermal_core.h has symbols that are not
exported. As drivers can be built as separated modules from thermal
core, I would not recommend include things in that header. The symbols
that are EXPORT_SYMBOL'ed are in thermal.h under include directory.

> 
> Cheers,
> Javi
> 
> > I dont think anymore, this should be a enum thermal_trip_type, but it has to be
> > generic across governors.
> > 
> > 
> > Thanks,
> > Lina

[-- Attachment #2: Digital signature --]
[-- Type: application/pgp-signature, Size: 473 bytes --]

Re: [PATCH v1 4/7] thermal: introduce the Power Allocator governor

[Lina Iyer]

On Tue, Feb 03 2015 at 08:30 -0700, Eduardo Valentin wrote:
>On Tue, Feb 03, 2015 at 01:03:37PM +0000, Javi Merino wrote:
>> On Mon, Feb 02, 2015 at 11:51:20PM +0000, Lina Iyer wrote:
>> > On Wed, Jan 28 2015 at 14:42 -0700, Javi Merino wrote:
>> > >The power allocator governor is a thermal governor that controls system
>> > >and device power allocation to control temperature.  Conceptually, the
>> > >implementation divides the sustainable power of a thermal zone among
>> > >all the heat sources in that zone.
>> > >
>> > >This governor relies on "power actors", entities that represent heat
>> > >sources.  They can report current and maximum power consumption and
>> > >can set a given maximum power consumption, usually via a cooling
>> > >device.
>> > >
>> > >The governor uses a Proportional Integral Derivative (PID) controller
>> > >driven by the temperature of the thermal zone.  The output of the
>> > >controller is a power budget that is then allocated to each power
>> > >actor that can have bearing on the temperature we are trying to
>> > >control.  It decides how much power to give each cooling device based
>> > >on the performance they are requesting.  The PID controller ensures
>> > >that the total power budget does not exceed the control temperature.
>> > >
>> > >Cc: Zhang Rui <rui.zhang@intel.com>
>> > >Cc: Eduardo Valentin <edubezval@gmail.com>
>> > >Signed-off-by: Punit Agrawal <punit.agrawal@arm.com>
>> > >Signed-off-by: Javi Merino <javi.merino@arm.com>
>> > >---
>> > > Documentation/thermal/power_allocator.txt | 241 +++++++++++++++
>> > > drivers/thermal/Kconfig                   |  15 +
>> > > drivers/thermal/Makefile                  |   1 +
>> > > drivers/thermal/power_allocator.c         | 478 ++++++++++++++++++++++++++++++
>> > > drivers/thermal/thermal_core.c            |   9 +-
>> > > drivers/thermal/thermal_core.h            |   8 +
>> > > include/linux/thermal.h                   |  37 ++-
>> > > 7 files changed, 782 insertions(+), 7 deletions(-)
>> > > create mode 100644 Documentation/thermal/power_allocator.txt
>> > > create mode 100644 drivers/thermal/power_allocator.c
>> > >
>> [...]
>> > >diff --git a/drivers/thermal/power_allocator.c b/drivers/thermal/power_allocator.c
>> > >new file mode 100644
>> > >index 000000000000..c929143aee67
>> > >--- /dev/null
>> > >+++ b/drivers/thermal/power_allocator.c
>> > >@@ -0,0 +1,478 @@
>> > >+/*
>> > >+ * A power allocator to manage temperature
>> > >+ *
>> > >+ * Copyright (C) 2014 ARM Ltd.
>> > >+ *
>> > >+ * This program is free software; you can redistribute it and/or modify
>> > >+ * it under the terms of the GNU General Public License version 2 as
>> > >+ * published by the Free Software Foundation.
>> > >+ *
>> > >+ * This program is distributed "as is" WITHOUT ANY WARRANTY of any
>> > >+ * kind, whether express or implied; without even the implied warranty
>> > >+ * of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
>> > >+ * GNU General Public License for more details.
>> > >+ */
>> > >+
>> > >+#define pr_fmt(fmt) "Power allocator: " fmt
>> > >+
>> > >+#include <linux/rculist.h>
>> > >+#include <linux/slab.h>
>> > >+#include <linux/thermal.h>
>> > >+
>> > >+#include "thermal_core.h"
>> > >+
>> > >+#define FRAC_BITS 10
>> > >+#define int_to_frac(x) ((x) << FRAC_BITS)
>> > >+#define frac_to_int(x) ((x) >> FRAC_BITS)
>> > >+
>> > >+/**
>> > >+ * mul_frac() - multiply two fixed-point numbers
>> > >+ * @x:        first multiplicand
>> > >+ * @y:        second multiplicand
>> > >+ *
>> > >+ * Return: the result of multiplying two fixed-point numbers.  The
>> > >+ * result is also a fixed-point number.
>> > >+ */
>> > >+static inline s64 mul_frac(s64 x, s64 y)
>> > >+{
>> > >+      return (x * y) >> FRAC_BITS;
>> > >+}
>> > >+
>> > >+enum power_allocator_trip_levels {
>> > >+      TRIP_SWITCH_ON = 0,     /* Switch on PID controller */
>> > >+      TRIP_MAX_DESIRED_TEMPERATURE, /* Temperature we are controlling for */
>> > >+
>> > >+      THERMAL_TRIP_NUM,
>> > >+};
>> >
>> > This has to be exported for tz's to respond to the request. See below.
>> >
>> > >+
>> > >+/**
>> > >+ * struct power_allocator_params - parameters for the power allocator governor
>> > >+ * @err_integral:     accumulated error in the PID controller.
>> > >+ * @prev_err: error in the previous iteration of the PID controller.
>> > >+ *            Used to calculate the derivative term.
>> > >+ */
>> > >+struct power_allocator_params {
>> > >+      s64 err_integral;
>> > >+      s32 prev_err;
>> > >+};
>> > >+
>> > >+/**
>> > >+ * pid_controller() - PID controller
>> > >+ * @tz:       thermal zone we are operating in
>> > >+ * @current_temp:     the current temperature in millicelsius
>> > >+ * @control_temp:     the target temperature in millicelsius
>> > >+ * @max_allocatable_power:    maximum allocatable power for this thermal zone
>> > >+ *
>> > >+ * This PID controller increases the available power budget so that the
>> > >+ * temperature of the thermal zone gets as close as possible to
>> > >+ * @control_temp and limits the power if it exceeds it.  k_po is the
>> > >+ * proportional term when we are overshooting, k_pu is the
>> > >+ * proportional term when we are undershooting.  integral_cutoff is a
>> > >+ * threshold below which we stop accumulating the error.  The
>> > >+ * accumulated error is only valid if the requested power will make
>> > >+ * the system warmer.  If the system is mostly idle, there's no point
>> > >+ * in accumulating positive error.
>> > >+ *
>> > >+ * Return: The power budget for the next period.
>> > >+ */
>> > >+static u32 pid_controller(struct thermal_zone_device *tz,
>> > >+                        unsigned long current_temp,
>> > >+                        unsigned long control_temp,
>> > >+                        u32 max_allocatable_power)
>> > >+{
>> > >+      s64 p, i, d, power_range;
>> > >+      s32 err, max_power_frac;
>> > >+      struct power_allocator_params *params = tz->governor_data;
>> > >+
>> > >+      max_power_frac = int_to_frac(max_allocatable_power);
>> > >+
>> > >+      err = ((s32)control_temp - (s32)current_temp);
>> > >+      err = int_to_frac(err);
>> > >+
>> > >+      /* Calculate the proportional term */
>> > >+      p = mul_frac(err < 0 ? tz->tzp->k_po : tz->tzp->k_pu, err);
>> > >+
>> > >+      /*
>> > >+       * Calculate the integral term
>> > >+       *
>> > >+       * if the error is less than cut off allow integration (but
>> > >+       * the integral is limited to max power)
>> > >+       */
>> > >+      i = mul_frac(tz->tzp->k_i, params->err_integral);
>> > >+
>> > >+      if (err < int_to_frac(tz->tzp->integral_cutoff)) {
>> > >+              s64 i_next = i + mul_frac(tz->tzp->k_i, err);
>> > >+
>> > >+              if (abs64(i_next) < max_power_frac) {
>> > >+                      i = i_next;
>> > >+                      params->err_integral += err;
>> > >+              }
>> > >+      }
>> > >+
>> > >+      /*
>> > >+       * Calculate the derivative term
>> > >+       *
>> > >+       * We do err - prev_err, so with a positive k_d, a decreasing
>> > >+       * error (i.e. driving closer to the line) results in less
>> > >+       * power being applied, slowing down the controller)
>> > >+       */
>> > >+      d = mul_frac(tz->tzp->k_d, err - params->prev_err);
>> > >+      params->prev_err = err;
>> > >+
>> > >+      power_range = p + i + d;
>> > >+
>> > >+      /* feed-forward the known sustainable dissipatable power */
>> > >+      power_range = tz->tzp->sustainable_power + frac_to_int(power_range);
>> > >+
>> > >+      return clamp(power_range, (s64)0, (s64)max_allocatable_power);
>> > >+}
>> > >+
>> > >+/**
>> > >+ * divvy_up_power() - divvy the allocated power between the actors
>> > >+ * @req_power:        each actor's requested power
>> > >+ * @max_power:        each actor's maximum available power
>> > >+ * @num_actors:       size of the @req_power, @max_power and @granted_power's array
>> > >+ * @total_req_power: sum of @req_power
>> > >+ * @power_range:      total allocated power
>> > >+ * @granted_power:    output array: each actor's granted power
>> > >+ *
>> > >+ * This function divides the total allocated power (@power_range)
>> > >+ * fairly between the actors.  It first tries to give each actor a
>> > >+ * share of the @power_range according to how much power it requested
>> > >+ * compared to the rest of the actors.  For example, if only one actor
>> > >+ * requests power, then it receives all the @power_range.  If
>> > >+ * three actors each requests 1mW, each receives a third of the
>> > >+ * @power_range.
>> > >+ *
>> > >+ * If any actor received more than their maximum power, then that
>> > >+ * surplus is re-divvied among the actors based on how far they are
>> > >+ * from their respective maximums.
>> > >+ *
>> > >+ * Granted power for each actor is written to @granted_power, which
>> > >+ * should've been allocated by the calling function.
>> > >+ */
>> > >+static void divvy_up_power(u32 *req_power, u32 *max_power, int num_actors,
>> > >+                         u32 total_req_power, u32 power_range,
>> > >+                         u32 *granted_power)
>> > >+{
>> > >+      u32 extra_power, capped_extra_power, extra_actor_power[num_actors];
>> > >+      int i;
>> > >+
>> > >+      /*
>> > >+       * Prevent division by 0 if none of the actors request power.
>> > >+       */
>> > >+      if (!total_req_power)
>> > >+              total_req_power = 1;
>> > >+
>> > >+      capped_extra_power = 0;
>> > >+      extra_power = 0;
>> > >+      for (i = 0; i < num_actors; i++) {
>> > >+              u64 req_range = req_power[i] * power_range;
>> > >+
>> > >+              granted_power[i] = div_u64(req_range, total_req_power);
>> > >+
>> > >+              if (granted_power[i] > max_power[i]) {
>> > >+                      extra_power += granted_power[i] - max_power[i];
>> > >+                      granted_power[i] = max_power[i];
>> > >+              }
>> > >+
>> > >+              extra_actor_power[i] = max_power[i] - granted_power[i];
>> > >+              capped_extra_power += extra_actor_power[i];
>> > >+      }
>> > >+
>> > >+      if (!extra_power)
>> > >+              return;
>> > >+
>> > >+      /*
>> > >+       * Re-divvy the reclaimed extra among actors based on
>> > >+       * how far they are from the max
>> > >+       */
>> > >+      extra_power = min(extra_power, capped_extra_power);
>> > >+      if (capped_extra_power > 0)
>> > >+              for (i = 0; i < num_actors; i++)
>> > >+                      granted_power[i] += (extra_actor_power[i] *
>> > >+                                      extra_power) / capped_extra_power;
>> > >+}
>> > >+
>> > >+static int allocate_power(struct thermal_zone_device *tz,
>> > >+                        unsigned long current_temp,
>> > >+                        unsigned long control_temp)
>> > >+{
>> > >+      struct thermal_instance *instance;
>> > >+      u32 *req_power, *max_power, *granted_power;
>> > >+      u32 total_req_power, max_allocatable_power;
>> > >+      u32 power_range;
>> > >+      int i, num_actors, ret = 0;
>> > >+
>> > >+      mutex_lock(&tz->lock);
>> > >+
>> > >+      num_actors = 0;
>> > >+      list_for_each_entry(instance, &tz->thermal_instances, tz_node)
>> > >+              if ((instance->trip == TRIP_MAX_DESIRED_TEMPERATURE) &&
>> > >+                  cdev_is_power_actor(instance->cdev))
>> > >+                      num_actors++;
>> > >+
>> > >+      req_power = devm_kcalloc(&tz->device, num_actors, sizeof(*req_power),
>> > >+                               GFP_KERNEL);
>> > >+      if (!req_power) {
>> > >+              ret = -ENOMEM;
>> > >+              goto unlock;
>> > >+      }
>> > >+
>> > >+      max_power = devm_kcalloc(&tz->device, num_actors, sizeof(*max_power),
>> > >+                               GFP_KERNEL);
>> > >+      if (!max_power) {
>> > >+              ret = -ENOMEM;
>> > >+              goto free_req_power;
>> > >+      }
>> > >+
>> > >+      granted_power = devm_kcalloc(&tz->device, num_actors,
>> > >+                                   sizeof(*granted_power), GFP_KERNEL);
>> > >+      if (!granted_power) {
>> > >+              ret = -ENOMEM;
>> > >+              goto free_max_power;
>> > >+      }
>> >
>> > You could optimize this allocation by allocating them together and then
>> > using an offset to get max_power and granted_power from req_power.
>>
>> Makes sense, I've changed it to:
>>
>> 	/*
>> 	 * We need to allocate three arrays of the same size:
>> 	 * req_power, max_power and granted_power.  They are going to
>> 	 * be needed until this function returns.  Allocate them all
>> 	 * in one go to simplify the allocation and deallocation
>> 	 * logic.
>> 	 */
>> 	BUILD_BUG_ON(sizeof(*req_power) != sizeof(*max_power));
>> 	BUILD_BUG_ON(sizeof(*req_power) != sizeof(*granted_power));
>> 	req_power = devm_kcalloc(&tz->device, num_actors * 3,
>> 				 sizeof(*req_power), GFP_KERNEL);
>> 	if (!req_power) {
>> 		ret = -ENOMEM;
>> 		goto unlock;
>> 	}
>>
>> 	max_power = &req_power[num_actors];
>> 	granted_power = &req_power[2 * num_actors];
>>
>> > >+
>> > >+      i = 0;
>> > >+      total_req_power = 0;
>> > >+      max_allocatable_power = 0;
>> > >+
>> > >+      list_for_each_entry(instance, &tz->thermal_instances, tz_node) {
>> > >+              struct thermal_cooling_device *cdev = instance->cdev;
>> > >+
>> > >+              if (instance->trip != TRIP_MAX_DESIRED_TEMPERATURE)
>> > >+                      continue;
>> > >+
>> > >+              if (!cdev_is_power_actor(cdev))
>> > >+                      continue;
>> > >+
>> > >+              if (cdev->ops->get_requested_power(cdev, tz, &req_power[i]))
>> > >+                      continue;
>> > >+
>> > >+              req_power[i] = frac_to_int(instance->weight * req_power[i]);
>> > >+
>> > >+              if (power_actor_get_max_power(cdev, tz, &max_power[i]))
>> > >+                      continue;
>> > >+
>> > >+              total_req_power += req_power[i];
>> > >+              max_allocatable_power += max_power[i];
>> > >+
>> > >+              i++;
>> > >+      }
>> > >+
>> > >+      power_range = pid_controller(tz, current_temp, control_temp,
>> > >+                                   max_allocatable_power);
>> > >+
>> > >+      divvy_up_power(req_power, max_power, num_actors, total_req_power,
>> > >+                     power_range, granted_power);
>> > >+
>> > >+      i = 0;
>> > >+      list_for_each_entry(instance, &tz->thermal_instances, tz_node) {
>> > >+              if (instance->trip != TRIP_MAX_DESIRED_TEMPERATURE)
>> > >+                      continue;
>> > >+
>> > >+              if (!cdev_is_power_actor(instance->cdev))
>> > >+                      continue;
>> > >+
>> > >+              power_actor_set_power(instance->cdev, instance,
>> > >+                                    granted_power[i]);
>> > >+
>> > >+              i++;
>> > >+      }
>> > >+
>> > >+      devm_kfree(&tz->device, granted_power);
>> > >+free_max_power:
>> > >+      devm_kfree(&tz->device, max_power);
>> > >+free_req_power:
>> > >+      devm_kfree(&tz->device, req_power);
>> > >+unlock:
>> > >+      mutex_unlock(&tz->lock);
>> > >+
>> > >+      return ret;
>> > >+}
>> > >+
>> > >+static int check_trips(struct thermal_zone_device *tz)
>> > >+{
>> > >+      int ret;
>> > >+      enum thermal_trip_type type;
>> > >+
>> > >+      if (tz->trips < THERMAL_TRIP_NUM)
>> > >+              return -EINVAL;
>> > >+
>> > >+      ret = tz->ops->get_trip_type(tz, TRIP_SWITCH_ON, &type);
>> > >+      if (ret)
>> > >+              return ret;
>> >
>> > TZ should be able to correctly enumerate the value of this definition in
>> > their driver.
>>
>> Right, drivers can use this enum so it should be in a header that they
>> can include.  I've moved the "enum power_allocator_trip_levels"
>> definition to thermal.h .  I considered drivers/thermal/thermal_core.h
>> but no drivers include that so it's probably not the right place
>> (others can correct me if I'm wrong).
>
>Well, I am not convinced drivers really need to be aware of these trip
>types. Which kind of drivers are we talking? Thermal zone drivers?
>cooling device drivers?

I am sorry, I am missing the point here. The Tz driver is requested to
return the type of an enum and if the enum is not shared, then how is
the driver expected to know what to return.
>
>Lina, do you have an existing driver (it can be yet to be posted) that
>would required using these types? To my understanding, these are simply
>for the governor internal control, drivers do not really need to understand
>the difference from one to another.

I am currently prototyping Javi's patches on QCOM existing solution. So its all WIP.
>
>The purpose of the .bind_to_tz callback is exactly to verify if the
>driver has added the required info into the thermal zone. Including the
>trip setup.

I may be completely off-base here and my understanding of trips is
questionable. But it seems like even with this callback, the driver
expected to know what the particular governor defines and needs from the
TZ.  The definitions may overlap and may mean different things in
different governros. To me a TZ driver should not care what the
governors are, but define some common parameters that any governor can
work with. Am I making sense here?

>
>Besides, the existing exposed trip types are sufficient, given that this
>series is in a working state. Unless we have a valid use case to change
>/ add trip types and expose them to driver, I would prefer to keep this
>simple.
>
>Side note, drivers/thermal/thermal_core.h has symbols that are not
>exported. As drivers can be built as separated modules from thermal
>core, I would not recommend include things in that header. The symbols
>that are EXPORT_SYMBOL'ed are in thermal.h under include directory.
>
>>
>> Cheers,
>> Javi
>>
>> > I dont think anymore, this should be a enum thermal_trip_type, but it has to be
>> > generic across governors.
>> >
>> >
>> > Thanks,
>> > Lina

Re: [PATCH v1 4/7] thermal: introduce the Power Allocator governor

[Eduardo Valentin]

[-- Attachment #1: Type: text/plain, Size: 2726 bytes --]

On Tue, Feb 03, 2015 at 10:32:11AM -0700, Lina Iyer wrote:

<big cut>

> >
> >Well, I am not convinced drivers really need to be aware of these trip
> >types. Which kind of drivers are we talking? Thermal zone drivers?
> >cooling device drivers?
> 
> I am sorry, I am missing the point here. The Tz driver is requested to
> return the type of an enum and if the enum is not shared, then how is
> the driver expected to know what to return.

Yeah, however, the only requirement I see for this governor is to have
two passive trip points.

> >
> >Lina, do you have an existing driver (it can be yet to be posted) that
> >would required using these types? To my understanding, these are simply
> >for the governor internal control, drivers do not really need to understand
> >the difference from one to another.
> 
> I am currently prototyping Javi's patches on QCOM existing solution. So its all WIP.

I see.

> >
> >The purpose of the .bind_to_tz callback is exactly to verify if the
> >driver has added the required info into the thermal zone. Including the
> >trip setup.
> 
> I may be completely off-base here and my understanding of trips is
> questionable. But it seems like even with this callback, the driver
> expected to know what the particular governor defines and needs from the
> TZ.  The definitions may overlap and may mean different things in
> different governros. To me a TZ driver should not care what the
> governors are, but define some common parameters that any governor can
> work with. Am I making sense here?


And that's is what I want to keep across the framework. Thermal zone
driver should not really be aware of governor details. Ideally, the
driver should provide a thermal zone that can be usable by different
governors. That is the ideal setup.

If we allow this new governor to have its own trip types, we will be
segregating thermal zones. And that should be avoid if possible.


> 
> >
> >Besides, the existing exposed trip types are sufficient, given that this
> >series is in a working state. Unless we have a valid use case to change
> >/ add trip types and expose them to driver, I would prefer to keep this
> >simple.
> >
> >Side note, drivers/thermal/thermal_core.h has symbols that are not
> >exported. As drivers can be built as separated modules from thermal
> >core, I would not recommend include things in that header. The symbols
> >that are EXPORT_SYMBOL'ed are in thermal.h under include directory.
> >
> >>
> >> Cheers,
> >> Javi
> >>
> >> > I dont think anymore, this should be a enum thermal_trip_type, but it has to be
> >> > generic across governors.
> >> >
> >> >
> >> > Thanks,
> >> > Lina
> 
> 

[-- Attachment #2: Digital signature --]
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Re: [PATCH v1 4/7] thermal: introduce the Power Allocator governor

[Lina Iyer]

On Tue, Feb 03 2015 at 12:20 -0700, Eduardo Valentin wrote:
>On Tue, Feb 03, 2015 at 10:32:11AM -0700, Lina Iyer wrote:
>
><big cut>
>
>> >
>> >Well, I am not convinced drivers really need to be aware of these trip
>> >types. Which kind of drivers are we talking? Thermal zone drivers?
>> >cooling device drivers?
>>
>> I am sorry, I am missing the point here. The Tz driver is requested to
>> return the type of an enum and if the enum is not shared, then how is
>> the driver expected to know what to return.
>
>Yeah, however, the only requirement I see for this governor is to have
>two passive trip points.
>
I understand, but the thermal zone may have multiple trip points that
are passive. How would the thermal zone indentify which trip point is of
interest to this particular governor.

>From what I see, every governor can define its number/type of trip
requirements and the TZ can define any number of trip points. I dont see
how I can write a TZ driver tha would work with a  governor in the
future that may expect more than 2 passive trip points.

>> >
>> >Lina, do you have an existing driver (it can be yet to be posted) that
>> >would required using these types? To my understanding, these are simply
>> >for the governor internal control, drivers do not really need to understand
>> >the difference from one to another.
>>
>> I am currently prototyping Javi's patches on QCOM existing solution. So its all WIP.
>
>I see.
>
>> >
>> >The purpose of the .bind_to_tz callback is exactly to verify if the
>> >driver has added the required info into the thermal zone. Including the
>> >trip setup.
>>
>> I may be completely off-base here and my understanding of trips is
>> questionable. But it seems like even with this callback, the driver
>> expected to know what the particular governor defines and needs from the
>> TZ.  The definitions may overlap and may mean different things in
>> different governros. To me a TZ driver should not care what the
>> governors are, but define some common parameters that any governor can
>> work with. Am I making sense here?
>
>
>And that's is what I want to keep across the framework. Thermal zone
>driver should not really be aware of governor details. Ideally, the
>driver should provide a thermal zone that can be usable by different
>governors. That is the ideal setup.

Right, but if the governors have no common enums, the driver would not know how
many trip points to implement.

>
>If we allow this new governor to have its own trip types, we will be
>segregating thermal zones. And that should be avoid if possible.
>
>
>>
>> >
>> >Besides, the existing exposed trip types are sufficient, given that this
>> >series is in a working state. Unless we have a valid use case to change
>> >/ add trip types and expose them to driver, I would prefer to keep this
>> >simple.
>> >
>> >Side note, drivers/thermal/thermal_core.h has symbols that are not
>> >exported. As drivers can be built as separated modules from thermal
>> >core, I would not recommend include things in that header. The symbols
>> >that are EXPORT_SYMBOL'ed are in thermal.h under include directory.
>> >
>> >>
>> >> Cheers,
>> >> Javi
>> >>
>> >> > I dont think anymore, this should be a enum thermal_trip_type, but it has to be
>> >> > generic across governors.
>> >> >
>> >> >
>> >> > Thanks,
>> >> > Lina
>>
>>

Re: [PATCH v1 4/7] thermal: introduce the Power Allocator governor

[Javi Merino]

Hi Lina,

On Wed, Feb 04, 2015 at 11:47:16PM +0000, Lina Iyer wrote:
> On Tue, Feb 03 2015 at 12:20 -0700, Eduardo Valentin wrote:
> >On Tue, Feb 03, 2015 at 10:32:11AM -0700, Lina Iyer wrote:
> >
> ><big cut>
> >
> >> >
> >> >Well, I am not convinced drivers really need to be aware of these trip
> >> >types. Which kind of drivers are we talking? Thermal zone drivers?
> >> >cooling device drivers?
> >>
> >> I am sorry, I am missing the point here. The Tz driver is requested to
> >> return the type of an enum and if the enum is not shared, then how is
> >> the driver expected to know what to return.
> >
> >Yeah, however, the only requirement I see for this governor is to have
> >two passive trip points.
> >
> I understand, but the thermal zone may have multiple trip points that
> are passive. How would the thermal zone indentify which trip point is of
> interest to this particular governor.
> 
> From what I see, every governor can define its number/type of trip
> requirements and the TZ can define any number of trip points. I dont see
> how I can write a TZ driver tha would work with a  governor in the
> future that may expect more than 2 passive trip points.
> 
> >> >
> >> >Lina, do you have an existing driver (it can be yet to be posted) that
> >> >would required using these types? To my understanding, these are simply
> >> >for the governor internal control, drivers do not really need to understand
> >> >the difference from one to another.
> >>
> >> I am currently prototyping Javi's patches on QCOM existing solution. So its all WIP.
> >
> >I see.
> >
> >> >
> >> >The purpose of the .bind_to_tz callback is exactly to verify if the
> >> >driver has added the required info into the thermal zone. Including the
> >> >trip setup.
> >>
> >> I may be completely off-base here and my understanding of trips is
> >> questionable. But it seems like even with this callback, the driver
> >> expected to know what the particular governor defines and needs from the
> >> TZ.  The definitions may overlap and may mean different things in
> >> different governros. To me a TZ driver should not care what the
> >> governors are, but define some common parameters that any governor can
> >> work with. Am I making sense here?
> >
> >
> >And that's is what I want to keep across the framework. Thermal zone
> >driver should not really be aware of governor details. Ideally, the
> >driver should provide a thermal zone that can be usable by different
> >governors. That is the ideal setup.
> 
> Right, but if the governors have no common enums, the driver would not know how
> many trip points to implement.

The constraint we currently have in the power allocator governor is
that trip points 0 and 1 must be passive.  Actually, all the governor
needs is two passive trip points, but they don't need to be pinned to
a specific number.  The "switch on" trip point has to be the first
passive trip point, but it need not be trip point 0.  We could relax
this constraint to just make it exactly that: "the first passive trip
point".  As for the control temperature, we could relax the constraint
to make it "the last passive trip point of the thermal zone".  Would
that work for you?

> >If we allow this new governor to have its own trip types, we will be
> >segregating thermal zones. And that should be avoid if possible.
> >
> >
> >>
> >> >
> >> >Besides, the existing exposed trip types are sufficient, given that this
> >> >series is in a working state. Unless we have a valid use case to change
> >> >/ add trip types and expose them to driver, I would prefer to keep this
> >> >simple.
> >> >
> >> >Side note, drivers/thermal/thermal_core.h has symbols that are not
> >> >exported. As drivers can be built as separated modules from thermal
> >> >core, I would not recommend include things in that header. The symbols
> >> >that are EXPORT_SYMBOL'ed are in thermal.h under include directory.
> >> >
> >> >>
> >> >> Cheers,
> >> >> Javi
> >> >>
> >> >> > I dont think anymore, this should be a enum thermal_trip_type, but it has to be
> >> >> > generic across governors.
> >> >> >
> >> >> >
> >> >> > Thanks,
> >> >> > Lina
> >>
> >>
> 
> 
> 

Re: [PATCH v1 4/7] thermal: introduce the Power Allocator governor

[Eduardo Valentin]

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Javi,

One minor clarification as follows:

On Wed, Jan 28, 2015 at 05:00:35PM +0000, Javi Merino wrote:

<big cut>

> +
> +k_d
> +---
> +
> +`k_d` configures the PID loop's derivative term constant.  It's
> +recommended to leave it as the default: 0.
> +

I know we are considering K_d = 0. However, ...

<yet another big cut>

> +	/*
> +	 * Calculate the derivative term
> +	 *
> +	 * We do err - prev_err, so with a positive k_d, a decreasing
> +	 * error (i.e. driving closer to the line) results in less
> +	 * power being applied, slowing down the controller)
> +	 */
> +	d = mul_frac(tz->tzp->k_d, err - params->prev_err);


... Shouldn't the above d component consider the rate of changes over time of the error?

I would expect you should do:
d = k_d * (dE / dt)

or

d = K_d * ((err - params->prev_err) / sampling_period)

in plain C:

+	d = mul_frac(tz->tzp->k_d, err - params->prev_err);
+	d /= tz->passive_polling; /* might require fixed point division */

---
Eduardo Valentin

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Re: [PATCH v1 4/7] thermal: introduce the Power Allocator governor

[Javi Merino]

Hi Eduardo,

On Tue, Feb 24, 2015 at 06:21:26PM +0000, Eduardo Valentin wrote:
> On Wed, Jan 28, 2015 at 05:00:35PM +0000, Javi Merino wrote:
> > +
> > +k_d
> > +---
> > +
> > +`k_d` configures the PID loop's derivative term constant.  It's
> > +recommended to leave it as the default: 0.
> > +
> 
> I know we are considering K_d = 0. However, ...
> 
> <yet another big cut>
> 
> > +	/*
> > +	 * Calculate the derivative term
> > +	 *
> > +	 * We do err - prev_err, so with a positive k_d, a decreasing
> > +	 * error (i.e. driving closer to the line) results in less
> > +	 * power being applied, slowing down the controller)
> > +	 */
> > +	d = mul_frac(tz->tzp->k_d, err - params->prev_err);
> 
> 
> ... Shouldn't the above d component consider the rate of changes over time of the error?
> 
> I would expect you should do:
> d = k_d * (dE / dt)
> 
> or
> 
> d = K_d * ((err - params->prev_err) / sampling_period)
> 
> in plain C:
> 
> +	d = mul_frac(tz->tzp->k_d, err - params->prev_err);
> +	d /= tz->passive_polling; /* might require fixed point division */

Could do.  To be honest, both k_d and passive_polling are constants so
I don't think you get anything by doing this other than the added
complexity of the fixed point division.  As you said, the default k_d
is 0, so I'm not strongly against it.

Cheers,
Javi

Re: [PATCH v1 4/7] thermal: introduce the Power Allocator governor

[Eduardo Valentin]

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On Wed, Feb 25, 2015 at 02:48:49PM +0000, Javi Merino wrote:
> Hi Eduardo,
> 
> On Tue, Feb 24, 2015 at 06:21:26PM +0000, Eduardo Valentin wrote:
> > On Wed, Jan 28, 2015 at 05:00:35PM +0000, Javi Merino wrote:
> > > +
> > > +k_d
> > > +---
> > > +
> > > +`k_d` configures the PID loop's derivative term constant.  It's
> > > +recommended to leave it as the default: 0.
> > > +
> > 
> > I know we are considering K_d = 0. However, ...
> > 
> > <yet another big cut>
> > 
> > > +	/*
> > > +	 * Calculate the derivative term
> > > +	 *
> > > +	 * We do err - prev_err, so with a positive k_d, a decreasing
> > > +	 * error (i.e. driving closer to the line) results in less
> > > +	 * power being applied, slowing down the controller)
> > > +	 */
> > > +	d = mul_frac(tz->tzp->k_d, err - params->prev_err);
> > 
> > 
> > ... Shouldn't the above d component consider the rate of changes over time of the error?
> > 
> > I would expect you should do:
> > d = k_d * (dE / dt)
> > 
> > or
> > 
> > d = K_d * ((err - params->prev_err) / sampling_period)
> > 
> > in plain C:
> > 
> > +	d = mul_frac(tz->tzp->k_d, err - params->prev_err);
> > +	d /= tz->passive_polling; /* might require fixed point division */
> 
> Could do.  To be honest, both k_d and passive_polling are constants so

Yes, I agree that they are constants. But if you deploy the thermal zone
with different sampling period on different devices, then the behavior
will change.

> I don't think you get anything by doing this other than the added
> complexity of the fixed point division.  As you said, the default k_d
> is 0, so I'm not strongly against it.

OK. Then I would prefer to add the division, as it makes the code aligned
to the concept.

> 
> Cheers,
> Javi

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Re: [PATCH v1 4/7] thermal: introduce the Power Allocator governor

[Javi Merino]

On Wed, Feb 25, 2015 at 07:00:38PM +0000, Eduardo Valentin wrote:
> On Wed, Feb 25, 2015 at 02:48:49PM +0000, Javi Merino wrote:
> > Hi Eduardo,
> > 
> > On Tue, Feb 24, 2015 at 06:21:26PM +0000, Eduardo Valentin wrote:
> > > On Wed, Jan 28, 2015 at 05:00:35PM +0000, Javi Merino wrote:
> > > > +
> > > > +k_d
> > > > +---
> > > > +
> > > > +`k_d` configures the PID loop's derivative term constant.  It's
> > > > +recommended to leave it as the default: 0.
> > > > +
> > > 
> > > I know we are considering K_d = 0. However, ...
> > > 
> > > <yet another big cut>
> > > 
> > > > +	/*
> > > > +	 * Calculate the derivative term
> > > > +	 *
> > > > +	 * We do err - prev_err, so with a positive k_d, a decreasing
> > > > +	 * error (i.e. driving closer to the line) results in less
> > > > +	 * power being applied, slowing down the controller)
> > > > +	 */
> > > > +	d = mul_frac(tz->tzp->k_d, err - params->prev_err);
> > > 
> > > 
> > > ... Shouldn't the above d component consider the rate of changes over time of the error?
> > > 
> > > I would expect you should do:
> > > d = k_d * (dE / dt)
> > > 
> > > or
> > > 
> > > d = K_d * ((err - params->prev_err) / sampling_period)
> > > 
> > > in plain C:
> > > 
> > > +	d = mul_frac(tz->tzp->k_d, err - params->prev_err);
> > > +	d /= tz->passive_polling; /* might require fixed point division */
> > 
> > Could do.  To be honest, both k_d and passive_polling are constants so
> 
> Yes, I agree that they are constants. But if you deploy the thermal zone
> with different sampling period on different devices, then the behavior
> will change.
> 
> > I don't think you get anything by doing this other than the added
> > complexity of the fixed point division.  As you said, the default k_d
> > is 0, so I'm not strongly against it.
> 
> OK. Then I would prefer to add the division, as it makes the code aligned
> to the concept.

Fair enough, I've added it to the code.  We will send a v2 later today
if all regressions pass.

Cheers,
Javi

Re: [PATCH v1 4/7] thermal: introduce the Power Allocator governor

[Eduardo Valentin]

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On Wed, Jan 28, 2015 at 05:00:35PM +0000, Javi Merino wrote:
> The power allocator governor is a thermal governor that controls system
> and device power allocation to control temperature.  Conceptually, the
> implementation divides the sustainable power of a thermal zone among
> all the heat sources in that zone.
> 
> This governor relies on "power actors", entities that represent heat
> sources.  They can report current and maximum power consumption and
> can set a given maximum power consumption, usually via a cooling
> device.
> 
> The governor uses a Proportional Integral Derivative (PID) controller
> driven by the temperature of the thermal zone.  The output of the
> controller is a power budget that is then allocated to each power
> actor that can have bearing on the temperature we are trying to
> control.  It decides how much power to give each cooling device based
> on the performance they are requesting.  The PID controller ensures
> that the total power budget does not exceed the control temperature.
> 
> Cc: Zhang Rui <rui.zhang@intel.com>
> Cc: Eduardo Valentin <edubezval@gmail.com>
> Signed-off-by: Punit Agrawal <punit.agrawal@arm.com>
> Signed-off-by: Javi Merino <javi.merino@arm.com>
> ---
>  Documentation/thermal/power_allocator.txt | 241 +++++++++++++++
>  drivers/thermal/Kconfig                   |  15 +
>  drivers/thermal/Makefile                  |   1 +
>  drivers/thermal/power_allocator.c         | 478 ++++++++++++++++++++++++++++++
>  drivers/thermal/thermal_core.c            |   9 +-
>  drivers/thermal/thermal_core.h            |   8 +
>  include/linux/thermal.h                   |  37 ++-
>  7 files changed, 782 insertions(+), 7 deletions(-)
>  create mode 100644 Documentation/thermal/power_allocator.txt
>  create mode 100644 drivers/thermal/power_allocator.c
> 
> diff --git a/Documentation/thermal/power_allocator.txt b/Documentation/thermal/power_allocator.txt
> new file mode 100644
> index 000000000000..c9604e76c544
> --- /dev/null
> +++ b/Documentation/thermal/power_allocator.txt
> @@ -0,0 +1,241 @@
> +Power allocator governor tunables
> +=================================
> +
> +Trip points
> +-----------
> +
> +The governor requires the following two passive trip points:
> +
> +1.  "switch on" trip point: temperature above which the governor
> +    control loop starts operating.
> +2.  "desired temperature" trip point: it should be higher than the
> +    "switch on" trip point.  This the target temperature the governor
> +    is controlling for.
> +
> +PID Controller
> +--------------
> +
> +The power allocator governor implements a
> +Proportional-Integral-Derivative controller (PID controller) with
> +temperature as the control input and power as the controlled output:
> +
> +    P_max = k_p * e + k_i * err_integral + k_d * diff_err + sustainable_power
> +
> +where
> +    e = desired_temperature - current_temperature
> +    err_integral is the sum of previous errors
> +    diff_err = e - previous_error
> +
> +It is similar to the one depicted below:
> +
> +                                      k_d
> +                                       |
> +current_temp                           |
> +     |                                 v
> +     |                +----------+   +---+
> +     |         +----->| diff_err |-->| X |------+
> +     |         |      +----------+   +---+      |
> +     |         |                                |      tdp        actor
> +     |         |                      k_i       |       |  get_requested_power()
> +     |         |                       |        |       |        |     |
> +     |         |                       |        |       |        |     | ...
> +     v         |                       v        v       v        v     v
> +   +---+       |      +-------+      +---+    +---+   +---+   +----------+
> +   | S |-------+----->| sum e |----->| X |--->| S |-->| S |-->|power     |
> +   +---+       |      +-------+      +---+    +---+   +---+   |allocation|
> +     ^         |                                ^             +----------+
> +     |         |                                |                |     |
> +     |         |        +---+                   |                |     |
> +     |         +------->| X |-------------------+                v     v
> +     |                  +---+                               granted performance
> +desired_temperature       ^
> +                          |
> +                          |
> +                      k_po/k_pu
> +
> +Sustainable power
> +-----------------
> +
> +An estimate of the sustainable dissipatable power (in mW) should be
> +provided while registering the thermal zone.  This estimates the
> +sustained power that can be dissipated at the desired control
> +temperature.  This is the maximum sustained power for allocation at
> +the desired maximum temperature.  The actual sustained power can vary
> +for a number of reasons.  The closed loop controller will take care of
> +variations such as environmental conditions, and some factors related
> +to the speed-grade of the silicon.  `sustainable_power` is therefore
> +simply an estimate, and may be tuned to affect the aggressiveness of
> +the thermal ramp. For reference, the sustainable power of a 4" phone
> +is typically 2000mW, while on a 10" tablet is around 4500mW (may vary
> +depending on screen size).
> +
> +If you are using device tree, do add it as a property of the
> +thermal-zone.  For example:
> +
> +	thermal-zones {
> +		soc_thermal {
> +			polling-delay = <1000>;
> +			polling-delay-passive = <100>;
> +			sustainable-power = <2500>;
> +			...
> +
> +Instead, if the thermal zone is registered from the platform code, pass a
> +`thermal_zone_params` that has a `sustainable_power`.  If no
> +`thermal_zone_params` were being passed, then something like below
> +will suffice:
> +
> +	static const struct thermal_zone_params tz_params = {
> +		.sustainable_power = 3500,
> +	};
> +
> +and then pass `tz_params` as the 5th parameter to
> +`thermal_zone_device_register()`
> +
> +k_po and k_pu
> +-------------
> +
> +The implementation of the PID controller in the power allocator
> +thermal governor allows the configuration of two proportional term
> +constants: `k_po` and `k_pu`.  `k_po` is the proportional term
> +constant during temperature overshoot periods (current temperature is
> +above "desired temperature" trip point).  Conversely, `k_pu` is the
> +proportional term constant during temperature undershoot periods
> +(current temperature below "desired temperature" trip point).
> +
> +These controls are intended as the primary mechanism for configuring
> +the permitted thermal "ramp" of the system.  For instance, a lower
> +`k_pu` value will provide a slower ramp, at the cost of capping
> +available capacity at a low temperature.  On the other hand, a high
> +value of `k_pu` will result in the governor granting very high power
> +whilst temperature is low, and may lead to temperature overshooting.
> +
> +The default value for `k_pu` is:
> +
> +    2 * sustainable_power / (desired_temperature - switch_on_temp)
> +
> +This means that at `switch_on_temp` the output of the controller's
> +proportional term will be 2 * `sustainable_power`.  The default value
> +for `k_po` is:
> +
> +    sustainable_power / (desired_temperature - switch_on_temp)
> +
> +Focusing on the proportional and feed forward values of the PID
> +controller equation we have:
> +
> +    P_max = k_p * e + sustainable_power
> +
> +The proportional term is proportional to the difference between the
> +desired temperature and the current one.  When the current temperature
> +is the desired one, then the proportional component is zero and
> +`P_max` = `sustainable_power`.  That is, the system should operate in
> +thermal equilibrium under constant load.  `sustainable_power` is only
> +an estimate, which is the reason for closed-loop control such as this.
> +
> +Expanding `k_pu` we get:
> +    P_max = 2 * sustainable_power * (T_set - T) / (T_set - T_on) +
> +        sustainable_power
> +
> +where
> +    T_set is the desired temperature
> +    T is the current temperature
> +    T_on is the switch on temperature
> +
> +When the current temperature is the switch_on temperature, the above
> +formula becomes:
> +
> +    P_max = 2 * sustainable_power * (T_set - T_on) / (T_set - T_on) +
> +        sustainable_power = 2 * sustainable_power + sustainable_power =
> +        3 * sustainable_power
> +
> +Therefore, the proportional term alone linearly decreases power from
> +3 * `sustainable_power` to `sustainable_power` as the temperature
> +rises from the switch on temperature to the desired temperature.
> +
> +k_i and integral_cutoff
> +-----------------------
> +
> +`k_i` configures the PID loop's integral term constant.  This term
> +allows the PID controller to compensate for long term drift and for
> +the quantized nature of the output control: cooling devices can't set
> +the exact power that the governor requests.  When the temperature
> +error is below `integral_cutoff`, errors are accumulated in the
> +integral term.  This term is then multiplied by `k_i` and the result
> +added to the output of the controller.  Typically `k_i` is set low (1
> +or 2) and `integral_cutoff` is 0.
> +
> +k_d
> +---
> +
> +`k_d` configures the PID loop's derivative term constant.  It's
> +recommended to leave it as the default: 0.
> +
> +Cooling device power API
> +========================
> +
> +Cooling devices controlled by this governor must supply the additional
> +"power" API in their `cooling_device_ops`.  It consists on three ops:
> +
> +1. int get_requested_power(struct thermal_cooling_device *cdev,
> +	struct thermal_zone_device *tz, u32 *power);
> +@cdev: The `struct thermal_cooling_device` pointer
> +@tz: thermal zone in which we are currently operating
> +@power: pointer in which to store the calculated power
> +
> +`get_requested_power()` calculates the power requested by the device
> +in milliwatts and stores it in @power .  It should return 0 on
> +success, -E* on failure.  This is currently used by the power
> +allocator governor to calculate how much power to give to each cooling
> +device.
> +
> +2. int state2power(struct thermal_cooling_device *cdev, struct
> +        thermal_zone_device *tz, unsigned long state, u32 *power);
> +@cdev: The `struct thermal_cooling_device` pointer
> +@tz: thermal zone in which we are currently operating
> +@state: A cooling device state
> +@power: pointer in which to store the equivalent power
> +
> +Convert cooling device state @state into power consumption in
> +milliwatts and store it in @power.  It should return 0 on success, -E*
> +on failure.  This is currently used by thermal core to calculate the
> +maximum power that an actor can consume.
> +
> +3. int power2state(struct thermal_cooling_device *cdev, u32 power,
> +	unsigned long *state);
> +@cdev: The `struct thermal_cooling_device` pointer
> +@power: power in milliwatts
> +@state: pointer in which to store the resulting state
> +
> +Calculate a cooling device state that would make the device consume at
> +most @power mW and store it in @state.  It should return 0 on success,
> +-E* on failure.  This is currently used by the thermal core to convert
> +a given power set by the power allocator governor to a state that the
> +cooling device can set.  It is a function because this conversion may
> +depend on external factors that may change so this function should the
> +best conversion given "current circumstances".
> +
> +Cooling device weights
> +----------------------
> +
> +Weights are a mechanism to bias the allocation among cooling
> +devices.  They express the relative power efficiency of different
> +cooling devices.  Higher weight can be used to express higher power
> +efficiency.  Weighting is relative such that if each cooling device
> +has a weight of one they are considered equal.  This is particularly
> +useful in heterogeneous systems where two cooling devices may perform
> +the same kind of compute, but with different efficiency.  For example,
> +a system with two different types of processors.
> +
> +Weights are passed as part of the thermal zone's
> +`thermal_bind_parameters`.
> +
> +Limitations of the power allocator governor
> +===========================================
> +
> +The power allocator governor's PID controller works best if there is a
> +periodic tick.  If you have a driver that calls
> +`thermal_zone_device_update()` (or anything that ends up calling the
> +governor's `throttle()` function) repetitively, the governor response
> +won't be very good.  Note that this is not particular to this
> +governor, step-wise will also misbehave if you call its throttle()
> +faster than the normal thermal framework tick (due to interrupts for
> +example) as it will overreact.
> diff --git a/drivers/thermal/Kconfig b/drivers/thermal/Kconfig
> index af40db0df58e..98a46383b19f 100644
> --- a/drivers/thermal/Kconfig
> +++ b/drivers/thermal/Kconfig
> @@ -71,6 +71,14 @@ config THERMAL_DEFAULT_GOV_USER_SPACE
>  	  Select this if you want to let the user space manage the
>  	  platform thermals.
>  
> +config THERMAL_DEFAULT_GOV_POWER_ALLOCATOR
> +	bool "power_allocator"
> +	select THERMAL_GOV_POWER_ALLOCATOR
> +	help
> +	  Select this if you want to control temperature based on
> +	  system and device power allocation. This governor can only
> +	  operate on cooling devices that implement the power API.
> +
>  endchoice
>  
>  config THERMAL_GOV_FAIR_SHARE
> @@ -99,6 +107,13 @@ config THERMAL_GOV_USER_SPACE
>  	help
>  	  Enable this to let the user space manage the platform thermals.
>  
> +config THERMAL_GOV_POWER_ALLOCATOR
> +	bool "Power allocator thermal governor"
> +	select THERMAL_POWER_ACTOR
> +	help
> +	  Enable this to manage platform thermals by dynamically
> +	  allocating and limiting power to devices.
> +
>  config CPU_THERMAL
>  	bool "generic cpu cooling support"
>  	depends on CPU_FREQ
> diff --git a/drivers/thermal/Makefile b/drivers/thermal/Makefile
> index fa0dc486790f..cd769ab06cbb 100644
> --- a/drivers/thermal/Makefile
> +++ b/drivers/thermal/Makefile
> @@ -14,6 +14,7 @@ thermal_sys-$(CONFIG_THERMAL_GOV_FAIR_SHARE)	+= fair_share.o
>  thermal_sys-$(CONFIG_THERMAL_GOV_BANG_BANG)	+= gov_bang_bang.o
>  thermal_sys-$(CONFIG_THERMAL_GOV_STEP_WISE)	+= step_wise.o
>  thermal_sys-$(CONFIG_THERMAL_GOV_USER_SPACE)	+= user_space.o
> +thermal_sys-$(CONFIG_THERMAL_GOV_POWER_ALLOCATOR)	+= power_allocator.o
>  
>  # cpufreq cooling
>  thermal_sys-$(CONFIG_CPU_THERMAL)	+= cpu_cooling.o
> diff --git a/drivers/thermal/power_allocator.c b/drivers/thermal/power_allocator.c
> new file mode 100644
> index 000000000000..c929143aee67
> --- /dev/null
> +++ b/drivers/thermal/power_allocator.c
> @@ -0,0 +1,478 @@
> +/*
> + * A power allocator to manage temperature
> + *
> + * Copyright (C) 2014 ARM Ltd.
> + *
> + * This program is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU General Public License version 2 as
> + * published by the Free Software Foundation.
> + *
> + * This program is distributed "as is" WITHOUT ANY WARRANTY of any
> + * kind, whether express or implied; without even the implied warranty
> + * of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
> + * GNU General Public License for more details.
> + */
> +
> +#define pr_fmt(fmt) "Power allocator: " fmt
> +
> +#include <linux/rculist.h>
> +#include <linux/slab.h>
> +#include <linux/thermal.h>
> +
> +#include "thermal_core.h"
> +
> +#define FRAC_BITS 10
> +#define int_to_frac(x) ((x) << FRAC_BITS)
> +#define frac_to_int(x) ((x) >> FRAC_BITS)
> +
> +/**
> + * mul_frac() - multiply two fixed-point numbers
> + * @x:	first multiplicand
> + * @y:	second multiplicand
> + *
> + * Return: the result of multiplying two fixed-point numbers.  The
> + * result is also a fixed-point number.
> + */
> +static inline s64 mul_frac(s64 x, s64 y)
> +{
> +	return (x * y) >> FRAC_BITS;
> +}
> +
> +enum power_allocator_trip_levels {
> +	TRIP_SWITCH_ON = 0,	/* Switch on PID controller */
> +	TRIP_MAX_DESIRED_TEMPERATURE, /* Temperature we are controlling for */
> +
> +	THERMAL_TRIP_NUM,
> +};
> +
> +/**
> + * struct power_allocator_params - parameters for the power allocator governor
> + * @err_integral:	accumulated error in the PID controller.
> + * @prev_err:	error in the previous iteration of the PID controller.
> + *		Used to calculate the derivative term.
> + */
> +struct power_allocator_params {
> +	s64 err_integral;
> +	s32 prev_err;
> +};
> +
> +/**
> + * pid_controller() - PID controller
> + * @tz:	thermal zone we are operating in
> + * @current_temp:	the current temperature in millicelsius
> + * @control_temp:	the target temperature in millicelsius
> + * @max_allocatable_power:	maximum allocatable power for this thermal zone
> + *
> + * This PID controller increases the available power budget so that the
> + * temperature of the thermal zone gets as close as possible to
> + * @control_temp and limits the power if it exceeds it.  k_po is the
> + * proportional term when we are overshooting, k_pu is the
> + * proportional term when we are undershooting.  integral_cutoff is a
> + * threshold below which we stop accumulating the error.  The
> + * accumulated error is only valid if the requested power will make
> + * the system warmer.  If the system is mostly idle, there's no point
> + * in accumulating positive error.
> + *
> + * Return: The power budget for the next period.
> + */
> +static u32 pid_controller(struct thermal_zone_device *tz,
> +			  unsigned long current_temp,
> +			  unsigned long control_temp,
> +			  u32 max_allocatable_power)
> +{
> +	s64 p, i, d, power_range;
> +	s32 err, max_power_frac;
> +	struct power_allocator_params *params = tz->governor_data;
> +
> +	max_power_frac = int_to_frac(max_allocatable_power);
> +
> +	err = ((s32)control_temp - (s32)current_temp);
> +	err = int_to_frac(err);
> +
> +	/* Calculate the proportional term */
> +	p = mul_frac(err < 0 ? tz->tzp->k_po : tz->tzp->k_pu, err);
> +
> +	/*
> +	 * Calculate the integral term
> +	 *
> +	 * if the error is less than cut off allow integration (but
> +	 * the integral is limited to max power)
> +	 */
> +	i = mul_frac(tz->tzp->k_i, params->err_integral);
> +
> +	if (err < int_to_frac(tz->tzp->integral_cutoff)) {
> +		s64 i_next = i + mul_frac(tz->tzp->k_i, err);
> +
> +		if (abs64(i_next) < max_power_frac) {
> +			i = i_next;
> +			params->err_integral += err;
> +		}
> +	}
> +
> +	/*
> +	 * Calculate the derivative term
> +	 *
> +	 * We do err - prev_err, so with a positive k_d, a decreasing
> +	 * error (i.e. driving closer to the line) results in less
> +	 * power being applied, slowing down the controller)
> +	 */
> +	d = mul_frac(tz->tzp->k_d, err - params->prev_err);
> +	params->prev_err = err;
> +
> +	power_range = p + i + d;
> +
> +	/* feed-forward the known sustainable dissipatable power */
> +	power_range = tz->tzp->sustainable_power + frac_to_int(power_range);
> +
> +	return clamp(power_range, (s64)0, (s64)max_allocatable_power);
> +}
> +
> +/**
> + * divvy_up_power() - divvy the allocated power between the actors
> + * @req_power:	each actor's requested power
> + * @max_power:	each actor's maximum available power
> + * @num_actors:	size of the @req_power, @max_power and @granted_power's array
> + * @total_req_power: sum of @req_power
> + * @power_range:	total allocated power
> + * @granted_power:	output array: each actor's granted power
> + *
> + * This function divides the total allocated power (@power_range)
> + * fairly between the actors.  It first tries to give each actor a
> + * share of the @power_range according to how much power it requested
> + * compared to the rest of the actors.  For example, if only one actor
> + * requests power, then it receives all the @power_range.  If
> + * three actors each requests 1mW, each receives a third of the
> + * @power_range.
> + *
> + * If any actor received more than their maximum power, then that
> + * surplus is re-divvied among the actors based on how far they are
> + * from their respective maximums.
> + *
> + * Granted power for each actor is written to @granted_power, which
> + * should've been allocated by the calling function.
> + */
> +static void divvy_up_power(u32 *req_power, u32 *max_power, int num_actors,
> +			   u32 total_req_power, u32 power_range,
> +			   u32 *granted_power)
> +{
> +	u32 extra_power, capped_extra_power, extra_actor_power[num_actors];

Just now I noticed this variable-size array. I know the number of actors
are constant, and in average it should be less than 10 in magnitude, but
I don't believe variable-sized arrays are a good practice in kernel.

Even though I don't see this one as a treat, can we avoid it?
Sparse error:

drivers/thermal/power_allocator.c:172:64: error: bad constant expression


> +	int i;
> +
> +	/*
> +	 * Prevent division by 0 if none of the actors request power.
> +	 */
> +	if (!total_req_power)
> +		total_req_power = 1;
> +
> +	capped_extra_power = 0;
> +	extra_power = 0;
> +	for (i = 0; i < num_actors; i++) {
> +		u64 req_range = req_power[i] * power_range;
> +
> +		granted_power[i] = div_u64(req_range, total_req_power);
> +
> +		if (granted_power[i] > max_power[i]) {
> +			extra_power += granted_power[i] - max_power[i];
> +			granted_power[i] = max_power[i];
> +		}
> +
> +		extra_actor_power[i] = max_power[i] - granted_power[i];
> +		capped_extra_power += extra_actor_power[i];
> +	}
> +
> +	if (!extra_power)
> +		return;
> +
> +	/*
> +	 * Re-divvy the reclaimed extra among actors based on
> +	 * how far they are from the max
> +	 */
> +	extra_power = min(extra_power, capped_extra_power);
> +	if (capped_extra_power > 0)
> +		for (i = 0; i < num_actors; i++)
> +			granted_power[i] += (extra_actor_power[i] *
> +					extra_power) / capped_extra_power;
> +}
> +
> +static int allocate_power(struct thermal_zone_device *tz,
> +			  unsigned long current_temp,
> +			  unsigned long control_temp)
> +{
> +	struct thermal_instance *instance;
> +	u32 *req_power, *max_power, *granted_power;
> +	u32 total_req_power, max_allocatable_power;
> +	u32 power_range;
> +	int i, num_actors, ret = 0;
> +
> +	mutex_lock(&tz->lock);
> +
> +	num_actors = 0;
> +	list_for_each_entry(instance, &tz->thermal_instances, tz_node)
> +		if ((instance->trip == TRIP_MAX_DESIRED_TEMPERATURE) &&
> +		    cdev_is_power_actor(instance->cdev))
> +			num_actors++;
> +
> +	req_power = devm_kcalloc(&tz->device, num_actors, sizeof(*req_power),
> +				 GFP_KERNEL);
> +	if (!req_power) {
> +		ret = -ENOMEM;
> +		goto unlock;
> +	}
> +
> +	max_power = devm_kcalloc(&tz->device, num_actors, sizeof(*max_power),
> +				 GFP_KERNEL);
> +	if (!max_power) {
> +		ret = -ENOMEM;
> +		goto free_req_power;
> +	}
> +
> +	granted_power = devm_kcalloc(&tz->device, num_actors,
> +				     sizeof(*granted_power), GFP_KERNEL);
> +	if (!granted_power) {
> +		ret = -ENOMEM;
> +		goto free_max_power;
> +	}
> +
> +	i = 0;
> +	total_req_power = 0;
> +	max_allocatable_power = 0;
> +
> +	list_for_each_entry(instance, &tz->thermal_instances, tz_node) {
> +		struct thermal_cooling_device *cdev = instance->cdev;
> +
> +		if (instance->trip != TRIP_MAX_DESIRED_TEMPERATURE)
> +			continue;
> +
> +		if (!cdev_is_power_actor(cdev))
> +			continue;
> +
> +		if (cdev->ops->get_requested_power(cdev, tz, &req_power[i]))
> +			continue;
> +
> +		req_power[i] = frac_to_int(instance->weight * req_power[i]);
> +
> +		if (power_actor_get_max_power(cdev, tz, &max_power[i]))
> +			continue;
> +
> +		total_req_power += req_power[i];
> +		max_allocatable_power += max_power[i];
> +
> +		i++;
> +	}
> +
> +	power_range = pid_controller(tz, current_temp, control_temp,
> +				     max_allocatable_power);
> +
> +	divvy_up_power(req_power, max_power, num_actors, total_req_power,
> +		       power_range, granted_power);
> +
> +	i = 0;
> +	list_for_each_entry(instance, &tz->thermal_instances, tz_node) {
> +		if (instance->trip != TRIP_MAX_DESIRED_TEMPERATURE)
> +			continue;
> +
> +		if (!cdev_is_power_actor(instance->cdev))
> +			continue;
> +
> +		power_actor_set_power(instance->cdev, instance,
> +				      granted_power[i]);
> +
> +		i++;
> +	}
> +
> +	devm_kfree(&tz->device, granted_power);
> +free_max_power:
> +	devm_kfree(&tz->device, max_power);
> +free_req_power:
> +	devm_kfree(&tz->device, req_power);
> +unlock:
> +	mutex_unlock(&tz->lock);
> +
> +	return ret;
> +}
> +
> +static int check_trips(struct thermal_zone_device *tz)
> +{
> +	int ret;
> +	enum thermal_trip_type type;
> +
> +	if (tz->trips < THERMAL_TRIP_NUM)
> +		return -EINVAL;
> +
> +	ret = tz->ops->get_trip_type(tz, TRIP_SWITCH_ON, &type);
> +	if (ret)
> +		return ret;
> +
> +	if (type != THERMAL_TRIP_PASSIVE)
> +		return -EINVAL;
> +
> +	ret = tz->ops->get_trip_type(tz, TRIP_MAX_DESIRED_TEMPERATURE, &type);
> +	if (ret)
> +		return ret;
> +
> +	if (type != THERMAL_TRIP_PASSIVE)
> +		return -EINVAL;
> +
> +	return ret;
> +}
> +
> +static void reset_pid_controller(struct power_allocator_params *params)
> +{
> +	params->err_integral = 0;
> +	params->prev_err = 0;
> +}
> +
> +static void allow_maximum_power(struct thermal_zone_device *tz)
> +{
> +	struct thermal_instance *instance;
> +
> +	list_for_each_entry(instance, &tz->thermal_instances, tz_node) {
> +		if ((instance->trip != TRIP_MAX_DESIRED_TEMPERATURE) ||
> +		    (!cdev_is_power_actor(instance->cdev)))
> +			continue;
> +
> +		instance->target = 0;
> +		instance->cdev->updated = false;
> +		thermal_cdev_update(instance->cdev);
> +	}
> +}
> +
> +/**
> + * power_allocator_bind() - bind the power_allocator governor to a thermal zone
> + * @tz:	thermal zone to bind it to
> + *
> + * Check that the thermal zone is valid for this governor, that is, it
> + * has two thermal trips.  If so, initialize the PID controller
> + * parameters and bind it to the thermal zone.
> + *
> + * Return: 0 on success, -EINVAL if the trips were invalid or -ENOMEM
> + * if we ran out of memory.
> + */
> +static int power_allocator_bind(struct thermal_zone_device *tz)
> +{
> +	int ret;
> +	struct power_allocator_params *params;
> +	unsigned long switch_on_temp, control_temp;
> +	u32 temperature_threshold;
> +
> +	ret = check_trips(tz);
> +	if (ret) {
> +		dev_err(&tz->device,
> +			"thermal zone %s has wrong trip setup for power allocator\n",
> +			tz->type);
> +		return ret;
> +	}
> +
> +	if (!tz->tzp || !tz->tzp->sustainable_power) {
> +		dev_err(&tz->device,
> +			"power_allocator: missing sustainable_power\n");
> +		return -EINVAL;
> +	}
> +
> +	params = devm_kzalloc(&tz->device, sizeof(*params), GFP_KERNEL);
> +	if (!params)
> +		return -ENOMEM;
> +
> +	ret = tz->ops->get_trip_temp(tz, TRIP_SWITCH_ON, &switch_on_temp);
> +	if (ret)
> +		goto free;
> +
> +	ret = tz->ops->get_trip_temp(tz, TRIP_MAX_DESIRED_TEMPERATURE,
> +				&control_temp);
> +	if (ret)
> +		goto free;
> +
> +	temperature_threshold = control_temp - switch_on_temp;
> +
> +	tz->tzp->k_po = tz->tzp->k_po ?:
> +		int_to_frac(tz->tzp->sustainable_power) / temperature_threshold;
> +	tz->tzp->k_pu = tz->tzp->k_pu ?:
> +		int_to_frac(2 * tz->tzp->sustainable_power) /
> +		temperature_threshold;
> +	tz->tzp->k_i = tz->tzp->k_i ?: int_to_frac(10) / 1000;
> +	/*
> +	 * The default for k_d and integral_cutoff is 0, so we can
> +	 * leave them as they are.
> +	 */
> +
> +	reset_pid_controller(params);
> +
> +	tz->governor_data = params;
> +
> +	return 0;
> +
> +free:
> +	devm_kfree(&tz->device, params);
> +	return ret;
> +}
> +
> +static void power_allocator_unbind(struct thermal_zone_device *tz)
> +{
> +	dev_dbg(&tz->device, "Unbinding from thermal zone %d\n", tz->id);
> +	devm_kfree(&tz->device, tz->governor_data);
> +	tz->governor_data = NULL;
> +}
> +
> +static int power_allocator_throttle(struct thermal_zone_device *tz, int trip)
> +{
> +	int ret;
> +	unsigned long switch_on_temp, control_temp, current_temp;
> +	struct power_allocator_params *params = tz->governor_data;
> +
> +	/*
> +	 * We get called for every trip point but we only need to do
> +	 * our calculations once
> +	 */
> +	if (trip != TRIP_MAX_DESIRED_TEMPERATURE)
> +		return 0;
> +
> +	ret = thermal_zone_get_temp(tz, &current_temp);
> +	if (ret) {
> +		dev_warn(&tz->device, "Failed to get temperature: %d\n", ret);
> +		return ret;
> +	}
> +
> +	ret = tz->ops->get_trip_temp(tz, TRIP_SWITCH_ON, &switch_on_temp);
> +	if (ret) {
> +		dev_warn(&tz->device,
> +			 "Failed to get switch on temperature: %d\n", ret);
> +		return ret;
> +	}
> +
> +	if (current_temp < switch_on_temp) {
> +		tz->passive = 0;
> +		reset_pid_controller(params);
> +		allow_maximum_power(tz);
> +		return 0;
> +	}
> +
> +	tz->passive = 1;
> +
> +	ret = tz->ops->get_trip_temp(tz, TRIP_MAX_DESIRED_TEMPERATURE,
> +				&control_temp);
> +	if (ret) {
> +		dev_warn(&tz->device,
> +			 "Failed to get the maximum desired temperature: %d\n",
> +			 ret);
> +		return ret;
> +	}
> +
> +	return allocate_power(tz, current_temp, control_temp);
> +}
> +
> +static struct thermal_governor thermal_gov_power_allocator = {
> +	.name		= "power_allocator",
> +	.bind_to_tz	= power_allocator_bind,
> +	.unbind_from_tz	= power_allocator_unbind,
> +	.throttle	= power_allocator_throttle,
> +};
> +
> +int thermal_gov_power_allocator_register(void)
> +{
> +	return thermal_register_governor(&thermal_gov_power_allocator);
> +}
> +
> +void thermal_gov_power_allocator_unregister(void)
> +{
> +	thermal_unregister_governor(&thermal_gov_power_allocator);
> +}
> diff --git a/drivers/thermal/thermal_core.c b/drivers/thermal/thermal_core.c
> index a01d4a72bd93..b77b5416929c 100644
> --- a/drivers/thermal/thermal_core.c
> +++ b/drivers/thermal/thermal_core.c
> @@ -1567,7 +1567,7 @@ static void remove_trip_attrs(struct thermal_zone_device *tz)
>  struct thermal_zone_device *thermal_zone_device_register(const char *type,
>  	int trips, int mask, void *devdata,
>  	struct thermal_zone_device_ops *ops,
> -	const struct thermal_zone_params *tzp,
> +	struct thermal_zone_params *tzp,
>  	int passive_delay, int polling_delay)
>  {
>  	struct thermal_zone_device *tz;
> @@ -1923,7 +1923,11 @@ static int __init thermal_register_governors(void)
>  	if (result)
>  		return result;
>  
> -	return thermal_gov_user_space_register();
> +	result = thermal_gov_user_space_register();
> +	if (result)
> +		return result;
> +
> +	return thermal_gov_power_allocator_register();
>  }
>  
>  static void thermal_unregister_governors(void)
> @@ -1932,6 +1936,7 @@ static void thermal_unregister_governors(void)
>  	thermal_gov_fair_share_unregister();
>  	thermal_gov_bang_bang_unregister();
>  	thermal_gov_user_space_unregister();
> +	thermal_gov_power_allocator_unregister();
>  }
>  
>  static int __init thermal_init(void)
> diff --git a/drivers/thermal/thermal_core.h b/drivers/thermal/thermal_core.h
> index 0531c752fbbb..28aa326806eb 100644
> --- a/drivers/thermal/thermal_core.h
> +++ b/drivers/thermal/thermal_core.h
> @@ -85,6 +85,14 @@ static inline int thermal_gov_user_space_register(void) { return 0; }
>  static inline void thermal_gov_user_space_unregister(void) {}
>  #endif /* CONFIG_THERMAL_GOV_USER_SPACE */
>  
> +#ifdef CONFIG_THERMAL_GOV_POWER_ALLOCATOR
> +int thermal_gov_power_allocator_register(void);
> +void thermal_gov_power_allocator_unregister(void);
> +#else
> +static inline int thermal_gov_power_allocator_register(void) { return 0; }
> +static inline void thermal_gov_power_allocator_unregister(void) {}
> +#endif /* CONFIG_THERMAL_GOV_POWER_ALLOCATOR */
> +
>  /* device tree support */
>  #ifdef CONFIG_THERMAL_OF
>  int of_parse_thermal_zones(void);
> diff --git a/include/linux/thermal.h b/include/linux/thermal.h
> index 288ac6fd743d..b42f790bb23c 100644
> --- a/include/linux/thermal.h
> +++ b/include/linux/thermal.h
> @@ -56,6 +56,8 @@
>  #define DEFAULT_THERMAL_GOVERNOR       "fair_share"
>  #elif defined(CONFIG_THERMAL_DEFAULT_GOV_USER_SPACE)
>  #define DEFAULT_THERMAL_GOVERNOR       "user_space"
> +#elif defined(CONFIG_THERMAL_DEFAULT_GOV_POWER_ALLOCATOR)
> +#define DEFAULT_THERMAL_GOVERNOR       "power_allocator"
>  #endif
>  
>  struct thermal_zone_device;
> @@ -151,8 +153,7 @@ struct thermal_attr {
>   * @devdata:	private pointer for device private data
>   * @trips:	number of trip points the thermal zone supports
>   * @passive_delay:	number of milliseconds to wait between polls when
> - *			performing passive cooling.  Currenty only used by the
> - *			step-wise governor
> + *			performing passive cooling.
>   * @polling_delay:	number of milliseconds to wait between polls when
>   *			checking whether trip points have been crossed (0 for
>   *			interrupt driven systems)
> @@ -162,7 +163,6 @@ struct thermal_attr {
>   * @last_temperature:	previous temperature read
>   * @emul_temperature:	emulated temperature when using CONFIG_THERMAL_EMULATION
>   * @passive:		1 if you've crossed a passive trip point, 0 otherwise.
> - *			Currenty only used by the step-wise governor.
>   * @forced_passive:	If > 0, temperature at which to switch on all ACPI
>   *			processor cooling devices.  Currently only used by the
>   *			step-wise governor.
> @@ -194,7 +194,7 @@ struct thermal_zone_device {
>  	int passive;
>  	unsigned int forced_passive;
>  	struct thermal_zone_device_ops *ops;
> -	const struct thermal_zone_params *tzp;
> +	struct thermal_zone_params *tzp;
>  	struct thermal_governor *governor;
>  	void *governor_data;
>  	struct list_head thermal_instances;
> @@ -269,6 +269,33 @@ struct thermal_zone_params {
>  
>  	int num_tbps;	/* Number of tbp entries */
>  	struct thermal_bind_params *tbp;
> +
> +	/*
> +	 * Sustainable power (heat) that this thermal zone can dissipate in
> +	 * mW
> +	 */
> +	u32 sustainable_power;
> +
> +	/*
> +	 * Proportional parameter of the PID controller when
> +	 * overshooting (i.e., when temperature is below the target)
> +	 */
> +	s32 k_po;
> +
> +	/*
> +	 * Proportional parameter of the PID controller when
> +	 * undershooting
> +	 */
> +	s32 k_pu;
> +
> +	/* Integral parameter of the PID controller */
> +	s32 k_i;
> +
> +	/* Derivative parameter of the PID controller */
> +	s32 k_d;
> +
> +	/* threshold below which the error is no longer accumulated */
> +	s32 integral_cutoff;
>  };
>  
>  struct thermal_genl_event {
> @@ -343,7 +370,7 @@ int power_actor_set_power(struct thermal_cooling_device *,
>  			  struct thermal_instance *, u32);
>  struct thermal_zone_device *thermal_zone_device_register(const char *, int, int,
>  		void *, struct thermal_zone_device_ops *,
> -		const struct thermal_zone_params *, int, int);
> +		struct thermal_zone_params *, int, int);
>  void thermal_zone_device_unregister(struct thermal_zone_device *);
>  
>  int thermal_zone_bind_cooling_device(struct thermal_zone_device *, int,
> -- 
> 1.9.1
> 

[-- Attachment #2: Digital signature --]
[-- Type: application/pgp-signature, Size: 473 bytes --]

[PATCH v1 5/7] thermal: add trace events to the power allocator governor

[Javi Merino]

Add trace events for the power allocator governor and the power actor
interface of the cpu cooling device.

Cc: Zhang Rui <rui.zhang@intel.com>
Cc: Eduardo Valentin <edubezval@gmail.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Ingo Molnar <mingo@redhat.com>
Signed-off-by: Javi Merino <javi.merino@arm.com>
---
 drivers/thermal/cpu_cooling.c                  | 31 +++++++++-
 drivers/thermal/power_allocator.c              | 22 ++++++-
 include/trace/events/thermal.h                 | 58 +++++++++++++++++++
 include/trace/events/thermal_power_allocator.h | 80 ++++++++++++++++++++++++++
 4 files changed, 187 insertions(+), 4 deletions(-)
 create mode 100644 include/trace/events/thermal_power_allocator.h

diff --git a/drivers/thermal/cpu_cooling.c b/drivers/thermal/cpu_cooling.c
index a639aaf228f5..1ca8fe580721 100644
--- a/drivers/thermal/cpu_cooling.c
+++ b/drivers/thermal/cpu_cooling.c
@@ -31,6 +31,8 @@
 #include <linux/cpu.h>
 #include <linux/cpu_cooling.h>
 
+#include <trace/events/thermal.h>
+
 /*
  * Cooling state <-> CPUFreq frequency
  *
@@ -534,12 +536,20 @@ static int cpufreq_get_requested_power(struct thermal_cooling_device *cdev,
 				       u32 *power)
 {
 	unsigned long freq;
-	int cpu, ret;
+	int i = 0, cpu, ret;
 	u32 static_power, dynamic_power, total_load = 0;
 	struct cpufreq_cooling_device *cpufreq_device = cdev->devdata;
+	u32 *load_cpu = NULL;
 
 	freq = cpufreq_quick_get(cpumask_any(&cpufreq_device->allowed_cpus));
 
+	if (trace_thermal_power_cpu_get_power_enabled()) {
+		u32 ncpus = cpumask_weight(&cpufreq_device->allowed_cpus);
+
+		load_cpu = devm_kcalloc(&cdev->device, ncpus, sizeof(*load_cpu),
+					GFP_KERNEL);
+	}
+
 	for_each_cpu(cpu, &cpufreq_device->allowed_cpus) {
 		u32 load;
 
@@ -549,14 +559,29 @@ static int cpufreq_get_requested_power(struct thermal_cooling_device *cdev,
 			load = 0;
 
 		total_load += load;
+		if (trace_thermal_power_cpu_limit_enabled() && load_cpu)
+			load_cpu[i] = load;
+
+		i++;
 	}
 
 	cpufreq_device->last_load = total_load;
 
 	dynamic_power = get_dynamic_power(cpufreq_device, freq);
 	ret = get_static_power(cpufreq_device, tz, freq, &static_power);
-	if (ret)
+	if (ret) {
+		if (load_cpu)
+			devm_kfree(&cdev->device, load_cpu);
 		return ret;
+	}
+
+	if (trace_thermal_power_cpu_limit_enabled() && load_cpu) {
+		trace_thermal_power_cpu_get_power(
+			&cpufreq_device->allowed_cpus,
+			freq, load_cpu, i, dynamic_power, static_power);
+
+		devm_kfree(&cdev->device, load_cpu);
+	}
 
 	*power = static_power + dynamic_power;
 	return 0;
@@ -664,6 +689,8 @@ static int cpufreq_power2state(struct thermal_cooling_device *cdev,
 		return -EINVAL;
 	}
 
+	trace_thermal_power_cpu_limit(&cpufreq_device->allowed_cpus,
+				      target_freq, *state, power);
 	return 0;
 }
 
diff --git a/drivers/thermal/power_allocator.c b/drivers/thermal/power_allocator.c
index c929143aee67..34c9a9025c54 100644
--- a/drivers/thermal/power_allocator.c
+++ b/drivers/thermal/power_allocator.c
@@ -19,6 +19,9 @@
 #include <linux/slab.h>
 #include <linux/thermal.h>
 
+#define CREATE_TRACE_POINTS
+#include <trace/events/thermal_power_allocator.h>
+
 #include "thermal_core.h"
 
 #define FRAC_BITS 10
@@ -124,7 +127,14 @@ static u32 pid_controller(struct thermal_zone_device *tz,
 	/* feed-forward the known sustainable dissipatable power */
 	power_range = tz->tzp->sustainable_power + frac_to_int(power_range);
 
-	return clamp(power_range, (s64)0, (s64)max_allocatable_power);
+	power_range = clamp(power_range, (s64)0, (s64)max_allocatable_power);
+
+	trace_thermal_power_allocator_pid(frac_to_int(err),
+					  frac_to_int(params->err_integral),
+					  frac_to_int(p), frac_to_int(i),
+					  frac_to_int(d), power_range);
+
+	return power_range;
 }
 
 /**
@@ -201,7 +211,7 @@ static int allocate_power(struct thermal_zone_device *tz,
 	struct thermal_instance *instance;
 	u32 *req_power, *max_power, *granted_power;
 	u32 total_req_power, max_allocatable_power;
-	u32 power_range;
+	u32 total_granted_power, power_range;
 	int i, num_actors, ret = 0;
 
 	mutex_lock(&tz->lock);
@@ -266,6 +276,7 @@ static int allocate_power(struct thermal_zone_device *tz,
 	divvy_up_power(req_power, max_power, num_actors, total_req_power,
 		       power_range, granted_power);
 
+	total_granted_power = 0;
 	i = 0;
 	list_for_each_entry(instance, &tz->thermal_instances, tz_node) {
 		if (instance->trip != TRIP_MAX_DESIRED_TEMPERATURE)
@@ -276,10 +287,17 @@ static int allocate_power(struct thermal_zone_device *tz,
 
 		power_actor_set_power(instance->cdev, instance,
 				      granted_power[i]);
+		total_granted_power += granted_power[i];
 
 		i++;
 	}
 
+	trace_thermal_power_allocator(req_power, total_req_power, granted_power,
+				      total_granted_power, num_actors,
+				      power_range, max_allocatable_power,
+				      current_temp,
+				      (s32)control_temp - (s32)current_temp);
+
 	devm_kfree(&tz->device, granted_power);
 free_max_power:
 	devm_kfree(&tz->device, max_power);
diff --git a/include/trace/events/thermal.h b/include/trace/events/thermal.h
index 0f4f95d63c03..8b1f80682b80 100644
--- a/include/trace/events/thermal.h
+++ b/include/trace/events/thermal.h
@@ -77,6 +77,64 @@ TRACE_EVENT(thermal_zone_trip,
 		__entry->trip_type)
 );
 
+TRACE_EVENT(thermal_power_cpu_get_power,
+	TP_PROTO(const struct cpumask *cpus, unsigned long freq, u32 *load,
+		size_t load_len, u32 dynamic_power, u32 static_power),
+
+	TP_ARGS(cpus, freq, load, load_len, dynamic_power, static_power),
+
+	TP_STRUCT__entry(
+		__bitmask(cpumask, num_possible_cpus())
+		__field(unsigned long, freq          )
+		__dynamic_array(u32,   load, load_len)
+		__field(size_t,        load_len      )
+		__field(u32,           dynamic_power )
+		__field(u32,           static_power  )
+	),
+
+	TP_fast_assign(
+		__assign_bitmask(cpumask, cpumask_bits(cpus),
+				num_possible_cpus());
+		__entry->freq = freq;
+		memcpy(__get_dynamic_array(load), load,
+			load_len * sizeof(*load));
+		__entry->load_len = load_len;
+		__entry->dynamic_power = dynamic_power;
+		__entry->static_power = static_power;
+	),
+
+	TP_printk("cpus=%s freq=%lu load={%s} dynamic_power=%d static_power=%d",
+		__get_bitmask(cpumask), __entry->freq,
+		__print_array(__get_dynamic_array(load), __entry->load_len, 4),
+		__entry->dynamic_power, __entry->static_power)
+);
+
+TRACE_EVENT(thermal_power_cpu_limit,
+	TP_PROTO(const struct cpumask *cpus, unsigned int freq,
+		unsigned long cdev_state, u32 power),
+
+	TP_ARGS(cpus, freq, cdev_state, power),
+
+	TP_STRUCT__entry(
+		__bitmask(cpumask, num_possible_cpus())
+		__field(unsigned int,  freq      )
+		__field(unsigned long, cdev_state)
+		__field(u32,           power     )
+	),
+
+	TP_fast_assign(
+		__assign_bitmask(cpumask, cpumask_bits(cpus),
+				num_possible_cpus());
+		__entry->freq = freq;
+		__entry->cdev_state = cdev_state;
+		__entry->power = power;
+	),
+
+	TP_printk("cpus=%s freq=%u cdev_state=%lu power=%u",
+		__get_bitmask(cpumask), __entry->freq, __entry->cdev_state,
+		__entry->power)
+);
+
 #endif /* _TRACE_THERMAL_H */
 
 /* This part must be outside protection */
diff --git a/include/trace/events/thermal_power_allocator.h b/include/trace/events/thermal_power_allocator.h
new file mode 100644
index 000000000000..c6a6d34858ef
--- /dev/null
+++ b/include/trace/events/thermal_power_allocator.h
@@ -0,0 +1,80 @@
+#undef TRACE_SYSTEM
+#define TRACE_SYSTEM thermal_power_allocator
+
+#if !defined(_TRACE_THERMAL_POWER_ALLOCATOR_H) || defined(TRACE_HEADER_MULTI_READ)
+#define _TRACE_THERMAL_POWER_ALLOCATOR_H
+
+#include <linux/tracepoint.h>
+
+TRACE_EVENT(thermal_power_allocator,
+	TP_PROTO(u32 *req_power, u32 total_req_power, u32 *granted_power,
+		u32 total_granted_power, size_t num_actors, u32 power_range,
+		u32 max_allocatable_power, unsigned long current_temp,
+		s32 delta_temp),
+	TP_ARGS(req_power, total_req_power, granted_power, total_granted_power,
+		num_actors, power_range, max_allocatable_power, current_temp,
+		delta_temp),
+	TP_STRUCT__entry(
+		__dynamic_array(u32,   req_power, num_actors    )
+		__field(u32,           total_req_power          )
+		__dynamic_array(u32,   granted_power, num_actors)
+		__field(u32,           total_granted_power      )
+		__field(size_t,        num_actors               )
+		__field(u32,           power_range              )
+		__field(u32,           max_allocatable_power    )
+		__field(unsigned long, current_temp             )
+		__field(s32,           delta_temp               )
+	),
+	TP_fast_assign(
+		memcpy(__get_dynamic_array(req_power), req_power,
+			num_actors * sizeof(*req_power));
+		__entry->total_req_power = total_req_power;
+		memcpy(__get_dynamic_array(granted_power), granted_power,
+			num_actors * sizeof(*granted_power));
+		__entry->total_granted_power = total_granted_power;
+		__entry->num_actors = num_actors;
+		__entry->power_range = power_range;
+		__entry->max_allocatable_power = max_allocatable_power;
+		__entry->current_temp = current_temp;
+		__entry->delta_temp = delta_temp;
+	),
+
+	TP_printk("req_power={%s} total_req_power=%u granted_power={%s} total_granted_power=%u power_range=%u max_allocatable_power=%u current_temperature=%lu delta_temperature=%d",
+		__print_array(__get_dynamic_array(req_power),
+                              __entry->num_actors, 4),
+		__entry->total_req_power,
+		__print_array(__get_dynamic_array(granted_power),
+                              __entry->num_actors, 4),
+		__entry->total_granted_power, __entry->power_range,
+		__entry->max_allocatable_power, __entry->current_temp,
+		__entry->delta_temp)
+);
+
+TRACE_EVENT(thermal_power_allocator_pid,
+	TP_PROTO(s32 err, s32 err_integral, s64 p, s64 i, s64 d, s32 output),
+	TP_ARGS(err, err_integral, p, i, d, output),
+	TP_STRUCT__entry(
+		__field(s32, err         )
+		__field(s32, err_integral)
+		__field(s64, p           )
+		__field(s64, i           )
+		__field(s64, d           )
+		__field(s32, output      )
+	),
+	TP_fast_assign(
+		__entry->err = err;
+		__entry->err_integral = err_integral;
+		__entry->p = p;
+		__entry->i = i;
+		__entry->d = d;
+		__entry->output = output;
+	),
+
+	TP_printk("err=%d err_integral=%d p=%lld i=%lld d=%lld output=%d",
+		__entry->err, __entry->err_integral,
+		__entry->p, __entry->i, __entry->d, __entry->output)
+);
+#endif /* _TRACE_THERMAL_POWER_ALLOCATOR_H */
+
+/* This part must be outside protection */
+#include <trace/define_trace.h>
-- 
1.9.1

Re: [PATCH v1 5/7] thermal: add trace events to the power allocator governor

[Steven Rostedt]

On Wed, 28 Jan 2015 17:00:36 +0000
Javi Merino <javi.merino@arm.com> wrote:

> +	if (trace_thermal_power_cpu_limit_enabled() && load_cpu) {
> +		trace_thermal_power_cpu_get_power(
> +			&cpufreq_device->allowed_cpus,
> +			freq, load_cpu, i, dynamic_power, static_power);
> +
> +		devm_kfree(&cdev->device, load_cpu);

You may want to move the devm_kfree() out of the
trace_thermal_power_cpu_limit_enabled() check. There could be a race
where that gets disabled while this function is running and you just
leaked memory.

	if (load_cpu)
		devm_kfree(&cdev->device, load_cpu);

should be done by itself.

-- Steve

> +	}
>  
>  	*power = static_power + dynamic_power;
>  	return 0;
> @@ -664,6 +689,8 @@ static int cpufreq_power2state(struct thermal_cooling_device *cdev,
>  		return -EINVAL;
>  	}
>  
> +	trace_thermal_power_cpu_limit(&cpufreq_device->allowed_cpus,
> +				      target_freq, *state, power);
>  	return 0;
>  }
>  

Re: [PATCH v1 5/7] thermal: add trace events to the power allocator governor

[Javi Merino]

On Wed, Jan 28, 2015 at 05:31:06PM +0000, Steven Rostedt wrote:
> On Wed, 28 Jan 2015 17:00:36 +0000
> Javi Merino <javi.merino@arm.com> wrote:
> 
> > +	if (trace_thermal_power_cpu_limit_enabled() && load_cpu) {
> > +		trace_thermal_power_cpu_get_power(
> > +			&cpufreq_device->allowed_cpus,
> > +			freq, load_cpu, i, dynamic_power, static_power);
> > +
> > +		devm_kfree(&cdev->device, load_cpu);
> 
> You may want to move the devm_kfree() out of the
> trace_thermal_power_cpu_limit_enabled() check. There could be a race
> where that gets disabled while this function is running and you just
> leaked memory.
> 
> 	if (load_cpu)
> 		devm_kfree(&cdev->device, load_cpu);
> 
> should be done by itself.

Good catch!  I've changed it to 

	if (load_cpu) {
		trace_thermal_power_cpu_get_power(
			&cpufreq_device->allowed_cpus,
			freq, load_cpu, i, dynamic_power, static_power);

		devm_kfree(&cdev->device, load_cpu);
	}

This way, if the trace is disabled while in the function,
trace_thermal_power_cpu_get_power() doesn't get executed but you free
load_cpu.  If the opposite happens (the trace gets enabled while in
the function), load_cpu is NULL and you don't pass the NULL pointer to
trace_thermal_power_cpu_get_power().

Cheers,
Javi

[PATCH v1 6/7] of: thermal: Introduce sustainable power for a thermal zone

[Javi Merino]

From: Punit Agrawal <punit.agrawal@arm.com>

Introduce an optional property called, sustainable-power, which
represents the power (in mW) which the thermal zone can safely
dissipate.

If provided the property is parsed and associated with the thermal
zone via the thermal zone parameters.

Cc: Zhang Rui <rui.zhang@intel.com>
Cc: Eduardo Valentin <edubezval@gmail.com>
Signed-off-by: Punit Agrawal <punit.agrawal@arm.com>
---
 Documentation/devicetree/bindings/thermal/thermal.txt | 9 +++++++++
 drivers/thermal/of-thermal.c                          | 4 ++++
 2 files changed, 13 insertions(+)

diff --git a/Documentation/devicetree/bindings/thermal/thermal.txt b/Documentation/devicetree/bindings/thermal/thermal.txt
index f5db6b72a36f..99d6608c9d5f 100644
--- a/Documentation/devicetree/bindings/thermal/thermal.txt
+++ b/Documentation/devicetree/bindings/thermal/thermal.txt
@@ -167,6 +167,13 @@ Optional property:
 			by means of sensor ID. Additional coefficients are
 			interpreted as constant offset.
 
+- sustainable-power:	An estimate of the sustainable power (in mW) that the
+  Type: unsigned	thermal zone can dissipate at the desired
+  Size: one cell	control temperature.  For reference, the
+			sustainable power of a 4'' phone is typically
+			2000mW, while on a 10'' tablet is around
+			4500mW.
+
 Note: The delay properties are bound to the maximum dT/dt (temperature
 derivative over time) in two situations for a thermal zone:
 (i)  - when passive cooling is activated (polling-delay-passive); and
@@ -546,6 +553,8 @@ thermal-zones {
 		 */
 		coefficients =		<1200	-345	890>;
 
+		sustainable-power = <2500>;
+
 		trips {
 			/* Trips are based on resulting linear equation */
 			cpu-trip: cpu-trip {
diff --git a/drivers/thermal/of-thermal.c b/drivers/thermal/of-thermal.c
index d717f3dab6f1..b44296541938 100644
--- a/drivers/thermal/of-thermal.c
+++ b/drivers/thermal/of-thermal.c
@@ -862,6 +862,7 @@ int __init of_parse_thermal_zones(void)
 	for_each_child_of_node(np, child) {
 		struct thermal_zone_device *zone;
 		struct thermal_zone_params *tzp;
+		u32 prop;
 
 		/* Check whether child is enabled or not */
 		if (!of_device_is_available(child))
@@ -888,6 +889,9 @@ int __init of_parse_thermal_zones(void)
 		/* No hwmon because there might be hwmon drivers registering */
 		tzp->no_hwmon = true;
 
+		if (!of_property_read_u32(child, "sustainable-power", &prop))
+			tzp->sustainable_power = prop;
+
 		zone = thermal_zone_device_register(child->name, tz->ntrips,
 						    0, tz,
 						    ops, tzp,
-- 
1.9.1

[PATCH v1 7/7] thermal: export thermal_zone_parameters to sysfs

[Javi Merino]

It's useful for tuning to be able to edit thermal_zone_parameters from
userspace.  Export them to the thermal_zone sysfs so that they can be
easily changed.

Cc: Zhang Rui <rui.zhang@intel.com>
Cc: Eduardo Valentin <edubezval@gmail.com>
Signed-off-by: Javi Merino <javi.merino@arm.com>
---
 Documentation/thermal/sysfs-api.txt |  52 +++++++++++++++++
 drivers/thermal/thermal_core.c      | 110 ++++++++++++++++++++++++++++++++++++
 2 files changed, 162 insertions(+)

diff --git a/Documentation/thermal/sysfs-api.txt b/Documentation/thermal/sysfs-api.txt
index 87519cb379ee..a95aabfad014 100644
--- a/Documentation/thermal/sysfs-api.txt
+++ b/Documentation/thermal/sysfs-api.txt
@@ -176,6 +176,12 @@ Thermal zone device sys I/F, created once it's registered:
     |---trip_point_[0-*]_type:	Trip point type
     |---trip_point_[0-*]_hyst:	Hysteresis value for this trip point
     |---emul_temp:		Emulated temperature set node
+    |---sustainable_power:      Sustainable dissipatable power
+    |---k_po:                   Proportional term during temperature overshoot
+    |---k_pu:                   Proportional term during temperature undershoot
+    |---k_i:                    PID's integral term in the power allocator gov
+    |---k_d:                    PID's derivative term in the power allocator
+    |---integral_cutoff:        Offset above which errors are accumulated
 
 Thermal cooling device sys I/F, created once it's registered:
 /sys/class/thermal/cooling_device[0-*]:
@@ -289,6 +295,52 @@ emul_temp
 	  because userland can easily disable the thermal policy by simply
 	  flooding this sysfs node with low temperature values.
 
+sustainable_power
+	An estimate of the sustained power that can be dissipated by
+	the thermal zone. Used by the power allocator governor. For
+	more information see Documentation/thermal/power_allocator.txt
+	Unit: milliwatts
+	RW, Optional
+
+k_po
+	The proportional term of the power allocator governor's PID
+	controller during temperature overshoot. Temperature overshoot
+	is when the current temperature is above the "desired
+	temperature" trip point. For more information see
+	Documentation/thermal/power_allocator.txt
+	RW, Optional
+
+k_pu
+	The proportional term of the power allocator governor's PID
+	controller during temperature undershoot. Temperature undershoot
+	is when the current temperature is below the "desired
+	temperature" trip point. For more information see
+	Documentation/thermal/power_allocator.txt
+	RW, Optional
+
+k_i
+	The integral term of the power allocator governor's PID
+	controller. This term allows the PID controller to compensate
+	for long term drift. For more information see
+	Documentation/thermal/power_allocator.txt
+	RW, Optional
+
+k_d
+	The derivative term of the power allocator governor's PID
+	controller. For more information see
+	Documentation/thermal/power_allocator.txt
+	RW, Optional
+
+integral_cutoff
+	Temperature offset from the desired temperature trip point
+	above which the integral term of the power allocator
+	governor's PID controller starts accumulating errors. For
+	example, if integral_cutoff is 0, then the integral term only
+	accumulates error when temperature is above the desired
+	temperature trip point. For more information see
+	Documentation/thermal/power_allocator.txt
+	RW, Optional
+
 *****************************
 * Cooling device attributes *
 *****************************
diff --git a/drivers/thermal/thermal_core.c b/drivers/thermal/thermal_core.c
index b77b5416929c..bde5e0442321 100644
--- a/drivers/thermal/thermal_core.c
+++ b/drivers/thermal/thermal_core.c
@@ -868,6 +868,111 @@ emul_temp_store(struct device *dev, struct device_attribute *attr,
 static DEVICE_ATTR(emul_temp, S_IWUSR, NULL, emul_temp_store);
 #endif/*CONFIG_THERMAL_EMULATION*/
 
+#ifdef CONFIG_THERMAL_GOV_POWER_ALLOCATOR
+
+static ssize_t
+sustainable_power_show(struct device *dev, struct device_attribute *devattr,
+		       char *buf)
+{
+	struct thermal_zone_device *tz = to_thermal_zone(dev);
+
+	if (tz->tzp)
+		return sprintf(buf, "%u\n", tz->tzp->sustainable_power);
+	else
+		return -EIO;
+}
+
+static ssize_t
+sustainable_power_store(struct device *dev, struct device_attribute *devattr,
+			const char *buf, size_t count)
+{
+	struct thermal_zone_device *tz = to_thermal_zone(dev);
+	u32 sustainable_power;
+
+	if (!tz->tzp)
+		return -EIO;
+
+	if (kstrtou32(buf, 10, &sustainable_power))
+		return -EINVAL;
+
+	tz->tzp->sustainable_power = sustainable_power;
+
+	return count;
+}
+static DEVICE_ATTR(sustainable_power, S_IWUSR | S_IRUGO, sustainable_power_show,
+		sustainable_power_store);
+
+#define create_s32_tzp_attr(name)					\
+	static ssize_t							\
+	name##_show(struct device *dev, struct device_attribute *devattr, \
+		char *buf)						\
+	{								\
+	struct thermal_zone_device *tz = to_thermal_zone(dev);		\
+									\
+	if (tz->tzp)							\
+		return sprintf(buf, "%u\n", tz->tzp->name);		\
+	else								\
+		return -EIO;						\
+	}								\
+									\
+	static ssize_t							\
+	name##_store(struct device *dev, struct device_attribute *devattr, \
+		const char *buf, size_t count)				\
+	{								\
+		struct thermal_zone_device *tz = to_thermal_zone(dev);	\
+		s32 value;						\
+									\
+		if (!tz->tzp)						\
+			return -EIO;					\
+									\
+		if (kstrtos32(buf, 10, &value))				\
+			return -EINVAL;					\
+									\
+		tz->tzp->name = value;					\
+									\
+		return count;						\
+	}								\
+	static DEVICE_ATTR(name, S_IWUSR | S_IRUGO, name##_show, name##_store)
+
+create_s32_tzp_attr(k_po);
+create_s32_tzp_attr(k_pu);
+create_s32_tzp_attr(k_i);
+create_s32_tzp_attr(k_d);
+create_s32_tzp_attr(integral_cutoff);
+#undef create_s32_tzp_attr
+
+static struct device_attribute *dev_tzp_attrs[] = {
+	&dev_attr_sustainable_power,
+	&dev_attr_k_po,
+	&dev_attr_k_pu,
+	&dev_attr_k_i,
+	&dev_attr_k_d,
+	&dev_attr_integral_cutoff,
+};
+
+static int create_power_allocator_tzp_attrs(struct device *dev)
+{
+	int i;
+
+	for (i = 0; i < ARRAY_SIZE(dev_tzp_attrs); i++) {
+		int ret;
+		struct device_attribute *dev_attr = dev_tzp_attrs[i];
+
+		ret = device_create_file(dev, dev_attr);
+		if (ret)
+			return ret;
+	}
+
+	return 0;
+}
+
+#else  /* !CONFIG_THERMAL_GOV_POWER_ALLOCATOR */
+static int create_power_allocator_tzp_attrs(struct device *dev)
+{
+	return 0;
+}
+#endif
+
 /**
  * power_actor_get_max_power() - get the maximum power that a cdev can consume
  * @cdev:	pointer to &thermal_cooling_device
@@ -1662,6 +1767,11 @@ struct thermal_zone_device *thermal_zone_device_register(const char *type,
 	if (result)
 		goto unregister;
 
+	/* Add power_allocator specific thermal zone params */
+	result = create_power_allocator_tzp_attrs(&tz->device);
+	if (result)
+		goto unregister;
+
 	/* Update 'this' zone's governor information */
 	mutex_lock(&thermal_governor_lock);
 
-- 
1.9.1

Re: [PATCH v1 0/7] The power allocator thermal governor

[Javi Merino]

Hi linux-pm,

On Wed, Jan 28, 2015 at 05:00:31PM +0000, Javi Merino wrote:
> The power allocator governor allocates device power to control
> temperature.  This requires transforming performance requests into
> requested power, which we do with an extended cooling device API
> introduced in patch 2 (thermal: extend the cooling device API to
> include power information).  Patch 3 (thermal: cpu_cooling: implement
> the power cooling device API) extends the cpu cooling device using a
> simple power model.

We have compared the Power Allocator governor against Step Wise and
generated a report:

https://wiki.linaro.org/WorkingGroups/PowerManagement/Resources/EAS/IPAEvidencev1

Cheers,
Javi & Kapileshwar (KP)