[PATCH 0/3] Hierarchical thermal zones

[PATCH 0/3] Hierarchical thermal zones

[Javi Merino]

This series adds the ability to create a hierarchy of thermal zones.
Thermal zones created via platform code or device tree can be set up
to calculate their temperature as the maximum of all its underlying
thermal zones.  This came up from discussions during LPC.

The first patch adds the basic support to thermal core.  Patch 2 adds
device tree support and patch 3 exports the hierarchy to sysfs.

Javi Merino (3):
  thermal: Add support for hierarchical thermal zones
  thermal: of: parse stacked thermal zones from device tree
  thermal: show the sub thermal zones in sysfs

 .../devicetree/bindings/thermal/thermal.txt        | 154 +++++++++++++++++-
 Documentation/thermal/sysfs-api.txt                |  40 +++++
 drivers/thermal/of-thermal.c                       |  98 ++++++++++++
 drivers/thermal/thermal_core.c                     | 173 ++++++++++++++++++++-
 include/linux/thermal.h                            |  19 +++
 5 files changed, 476 insertions(+), 8 deletions(-)

-- 
1.9.1

[PATCH 1/3] thermal: Add support for hierarchical thermal zones

[Javi Merino]

Add the ability to stack thermal zones on top of each other, creating a
hierarchy of thermal zones.

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 |  35 +++++++++
 drivers/thermal/thermal_core.c      | 151 ++++++++++++++++++++++++++++++++++--
 include/linux/thermal.h             |  16 ++++
 3 files changed, 197 insertions(+), 5 deletions(-)

diff --git a/Documentation/thermal/sysfs-api.txt b/Documentation/thermal/sysfs-api.txt
index 10f062ea6bc2..5650b7eaaf7e 100644
--- a/Documentation/thermal/sysfs-api.txt
+++ b/Documentation/thermal/sysfs-api.txt
@@ -72,6 +72,41 @@ temperature) and throttle appropriate devices.
     It deletes the corresponding entry form /sys/class/thermal folder and
     unbind all the thermal cooling devices it uses.
 
+
+1.1.3 int thermal_zone_add_subtz(struct thermal_zone_device *tz,
+                                 struct thermal_zone_device *subtz)
+
+    Add subtz to the list of slaves of tz.  When calculating the
+    temperature of thermal zone tz, report the maximum of the slave
+    thermal zones.  This lets you create a hierarchy of thermal zones.
+    The hierarchy must be a Direct Acyclic Graph (DAG).  If a loop is
+    detected, thermal_zone_get_temp() will return -EDEADLK to prevent
+    the deadlock.  thermal_zone_add_subtz() does not affect subtz.
+
+    For example, if you have an SoC with a thermal sensor in each cpu
+    of the two cpus you could have a thermal zone to monitor each
+    sensor, let's call them cpu0_tz and cpu1_tz.  You could then have a
+    a SoC thermal zone (soc_tz) without a get_temp() op which can be
+    configured like this:
+
+    thermal_zone_add_subtz(soc_tz, cpu0_tz);
+    thermal_zone_add_subtz(soc_tz, cpu1_tz);
+
+    Now soc_tz's temperature is the maximum of cpu0_tz and cpu1_tz.
+    Furthermore, soc_tz could be combined with other thermal zones to
+    create a "device" thermal zone.
+
+
+1.1.4 int thermal_zone_del_subtz(struct thermal_zone_device *tz,
+                                 struct thermal_zone_device *subtz)
+
+    Delete subtz from the slave thermal zones of tz.  This basically
+    reverses what thermal_zone_add_subtz() does.  If tz still has
+    other slave thermal zones, its temperature would be the maximum of
+    the remaining slave thermal zones.  If tz no longer has slave
+    thermal zones, thermal_zone_get_temp() will return -EINVAL.
+
+
 1.2 thermal cooling device interface
 1.2.1 struct thermal_cooling_device *thermal_cooling_device_register(char *name,
 		void *devdata, struct thermal_cooling_device_ops *)
diff --git a/drivers/thermal/thermal_core.c b/drivers/thermal/thermal_core.c
index d9e525cc9c1c..a2ab482337f3 100644
--- a/drivers/thermal/thermal_core.c
+++ b/drivers/thermal/thermal_core.c
@@ -61,6 +61,11 @@ static DEFINE_MUTEX(thermal_governor_lock);
 
 static struct thermal_governor *def_governor;
 
+struct thermal_zone_link {
+	struct thermal_zone_device *slave;
+	struct list_head node;
+};
+
 static struct thermal_governor *__find_governor(const char *name)
 {
 	struct thermal_governor *pos;
@@ -465,6 +470,42 @@ static void handle_thermal_trip(struct thermal_zone_device *tz, int trip)
 }
 
 /**
+ * get_subtz_temp() - get the maximum temperature of all the sub thermal zones
+ * @tz:	thermal zone pointer
+ * @temp: pointer in which to store the result
+ *
+ * Go through all the thermal zones listed in @tz slave_tzs and
+ * calculate the maximum temperature of all of them.  The maximum
+ * temperature is stored in @temp.
+ *
+ * Return: 0 on success, -EINVAL if there are no slave thermal zones,
+ * -E* if thermal_zone_get_temp() fails for any of the slave thermal
+ * zones.
+ */
+static int get_subtz_temp(struct thermal_zone_device *tz, int *temp)
+{
+	struct thermal_zone_link *link;
+	int max_temp = INT_MIN;
+
+	if (list_empty(&tz->slave_tzs))
+		return -EINVAL;
+
+	list_for_each_entry(link, &tz->slave_tzs, node) {
+		int this_temp, ret;
+
+		ret = thermal_zone_get_temp(link->slave, &this_temp);
+		if (ret)
+			return ret;
+
+		if (this_temp > max_temp)
+			max_temp = this_temp;
+	}
+
+	*temp = max_temp;
+	return 0;
+}
+
+/**
  * thermal_zone_get_temp() - returns the temperature of a thermal zone
  * @tz: a valid pointer to a struct thermal_zone_device
  * @temp: a valid pointer to where to store the resulting temperature.
@@ -481,11 +522,22 @@ int thermal_zone_get_temp(struct thermal_zone_device *tz, int *temp)
 	int crit_temp = INT_MAX;
 	enum thermal_trip_type type;
 
-	if (!tz || IS_ERR(tz) || !tz->ops->get_temp)
+	if (!tz || IS_ERR(tz))
 		goto exit;
 
+	/* Avoid loops */
+	if (tz->slave_tz_visited)
+		return -EDEADLK;
+
 	mutex_lock(&tz->lock);
 
+	tz->slave_tz_visited = true;
+
+	if (!tz->ops->get_temp) {
+		ret = get_subtz_temp(tz, temp);
+		goto unlock;
+	}
+
 	ret = tz->ops->get_temp(tz, temp);
 
 	if (IS_ENABLED(CONFIG_THERMAL_EMULATION) && tz->emul_temperature) {
@@ -506,7 +558,9 @@ int thermal_zone_get_temp(struct thermal_zone_device *tz, int *temp)
 		if (!ret && *temp < crit_temp)
 			*temp = tz->emul_temperature;
 	}
- 
+
+unlock:
+	tz->slave_tz_visited = false;
 	mutex_unlock(&tz->lock);
 exit:
 	return ret;
@@ -540,9 +594,6 @@ void thermal_zone_device_update(struct thermal_zone_device *tz)
 {
 	int count;
 
-	if (!tz->ops->get_temp)
-		return;
-
 	update_temperature(tz);
 
 	for (count = 0; count < tz->trips; count++)
@@ -1789,6 +1840,7 @@ struct thermal_zone_device *thermal_zone_device_register(const char *type,
 	if (!tz)
 		return ERR_PTR(-ENOMEM);
 
+	INIT_LIST_HEAD(&tz->slave_tzs);
 	INIT_LIST_HEAD(&tz->thermal_instances);
 	idr_init(&tz->idr);
 	mutex_init(&tz->lock);
@@ -1921,6 +1973,7 @@ void thermal_zone_device_unregister(struct thermal_zone_device *tz)
 	const struct thermal_zone_params *tzp;
 	struct thermal_cooling_device *cdev;
 	struct thermal_zone_device *pos = NULL;
+	struct thermal_zone_link *link, *tmp;
 
 	if (!tz)
 		return;
@@ -1958,6 +2011,9 @@ void thermal_zone_device_unregister(struct thermal_zone_device *tz)
 
 	mutex_unlock(&thermal_list_lock);
 
+	list_for_each_entry_safe(link, tmp, &tz->slave_tzs, node)
+		thermal_zone_del_subtz(tz, link->slave);
+
 	thermal_zone_device_set_polling(tz, 0);
 
 	if (tz->type[0])
@@ -1980,6 +2036,91 @@ void thermal_zone_device_unregister(struct thermal_zone_device *tz)
 EXPORT_SYMBOL_GPL(thermal_zone_device_unregister);
 
 /**
+ * thermal_zone_add_subtz() - add a sub thermal zone to a thermal zone
+ * @tz:	pointer to the master thermal zone
+ * @subtz: pointer to the slave thermal zone
+ *
+ * Add @subtz to the list of slave thermal zones of @tz.  If @tz
+ * doesn't provide a get_temp() op, its temperature will be calculated
+ * as a combination of the temperatures of its sub thermal zones.  See
+ * get_sub_tz_temp() for more information on how it's calculated.
+ *
+ * Return: 0 on success, -EINVAL if @tz or @subtz are not valid
+ * pointers, -EEXIST if the link already exists or -ENOMEM if we ran
+ * out of memory.
+ */
+int thermal_zone_add_subtz(struct thermal_zone_device *tz,
+			   struct thermal_zone_device *subtz)
+{
+	int ret;
+	struct thermal_zone_link *link;
+
+	if (IS_ERR_OR_NULL(tz) || IS_ERR_OR_NULL(subtz))
+		return -EINVAL;
+
+	mutex_lock(&tz->lock);
+
+	list_for_each_entry(link, &tz->slave_tzs, node) {
+		if (link->slave == subtz) {
+			ret = -EEXIST;
+			goto unlock;
+		}
+	}
+
+	link = kzalloc(sizeof(*link), GFP_KERNEL);
+	if (!link) {
+		ret = -ENOMEM;
+		goto unlock;
+	}
+
+	link->slave = subtz;
+	list_add_tail(&link->node, &tz->slave_tzs);
+
+	ret = 0;
+
+unlock:
+	mutex_unlock(&tz->lock);
+
+	return ret;
+}
+
+/**
+ * thermal_zone_del_subtz() - delete a sub thermal zone from its master thermal zone
+ * @tz:	pointer to the master thermal zone
+ * @subtz: pointer to the slave thermal zone
+ *
+ * Remove @subtz from the list of slave thermal zones of @tz.
+ *
+ * Return: 0 on success, -EINVAL if either thermal is invalid or if
+ * @subtz is not a slave of @tz.
+ */
+int thermal_zone_del_subtz(struct thermal_zone_device *tz,
+			   struct thermal_zone_device *subtz)
+{
+	int ret = -EINVAL;
+	struct thermal_zone_link *link;
+
+	if (IS_ERR_OR_NULL(tz) || IS_ERR_OR_NULL(subtz))
+		return -EINVAL;
+
+	mutex_lock(&tz->lock);
+
+	list_for_each_entry(link, &tz->slave_tzs, node) {
+		if (link->slave == subtz) {
+			list_del(&link->node);
+			kfree(link);
+
+			ret = 0;
+			break;
+		}
+	}
+
+	mutex_unlock(&tz->lock);
+
+	return ret;
+}
+
+/**
  * thermal_zone_get_zone_by_name() - search for a zone and returns its ref
  * @name: thermal zone name to fetch the temperature
  *
diff --git a/include/linux/thermal.h b/include/linux/thermal.h
index 157d366e761b..7996b4e7e61a 100644
--- a/include/linux/thermal.h
+++ b/include/linux/thermal.h
@@ -168,6 +168,8 @@ struct thermal_attr {
  * @ops:	operations this &thermal_zone_device supports
  * @tzp:	thermal zone parameters
  * @governor:	pointer to the governor for this thermal zone
+ * @slave_tzs:	list of thermal zones that are a slave of this thermal zone
+ * @slave_tz_visited: used to detect loops in stacked thermal zones
  * @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
@@ -195,6 +197,8 @@ struct thermal_zone_device {
 	struct thermal_zone_device_ops *ops;
 	struct thermal_zone_params *tzp;
 	struct thermal_governor *governor;
+	struct list_head slave_tzs;
+	bool slave_tz_visited;
 	void *governor_data;
 	struct list_head thermal_instances;
 	struct idr idr;
@@ -403,6 +407,10 @@ struct thermal_cooling_device *
 thermal_of_cooling_device_register(struct device_node *np, char *, void *,
 				   const struct thermal_cooling_device_ops *);
 void thermal_cooling_device_unregister(struct thermal_cooling_device *);
+int thermal_zone_add_subtz(struct thermal_zone_device *,
+			   struct thermal_zone_device *);
+int thermal_zone_del_subtz(struct thermal_zone_device *,
+			   struct thermal_zone_device *);
 struct thermal_zone_device *thermal_zone_get_zone_by_name(const char *name);
 int thermal_zone_get_temp(struct thermal_zone_device *tz, int *temp);
 
@@ -455,6 +463,14 @@ thermal_of_cooling_device_register(struct device_node *np,
 static inline void thermal_cooling_device_unregister(
 	struct thermal_cooling_device *cdev)
 { }
+static inline struct thermal_zone_device *
+thermal_zone_add_subtz(struct thermal_zone_device *tz,
+		       struct thermal_zone_device *subtz)
+{ return -ENODEV; }
+static inline struct thermal_zone_device *
+thermal_zone_del_subtz(struct thermal_zone_device *tz,
+		       struct thermal_zone_device *subtz)
+{ return -ENODEV; }
 static inline struct thermal_zone_device *thermal_zone_get_zone_by_name(
 		const char *name)
 { return ERR_PTR(-ENODEV); }
-- 
1.9.1

[PATCH 2/3] thermal: of: parse stacked thermal zones from device tree

[Javi Merino]

Let device tree set thermal zones in the thermal-sensors list of
phandles and set up the thermal zone hierarchy based on the information
present there.

Cc: Zhang Rui <rui.zhang@intel.com>
Cc: Eduardo Valentin <edubezval@gmail.com>
Signed-off-by: Javi Merino <javi.merino@arm.com>
---
 .../devicetree/bindings/thermal/thermal.txt        | 154 ++++++++++++++++++++-
 drivers/thermal/of-thermal.c                       |  98 +++++++++++++
 2 files changed, 249 insertions(+), 3 deletions(-)

diff --git a/Documentation/devicetree/bindings/thermal/thermal.txt b/Documentation/devicetree/bindings/thermal/thermal.txt
index 41b817f7b670..52b7e9ae3b4d 100644
--- a/Documentation/devicetree/bindings/thermal/thermal.txt
+++ b/Documentation/devicetree/bindings/thermal/thermal.txt
@@ -145,9 +145,12 @@ Required properties:
   Size: one cell
 
 - thermal-sensors:	A list of thermal sensor phandles and sensor specifier
-  Type: list of 	used while monitoring the thermal zone.
-  phandles + sensor
-  specifier
+  Type: list of 	used while monitoring the thermal zone. The phandles
+  phandles + sensor	can point to thermal sensors or other thermal zone
+  specifier		nodes. If it points to other thermal zone
+			nodes you should omit the sensor specifier
+			and set #thermal-sensor-cells to 0 for the
+			thermal zone.
 
 - trips:		A sub-node which is a container of only trip point nodes
   Type: sub-node	required to describe the thermal zone.
@@ -603,3 +606,148 @@ thermal-zones {
 The above example is a mix of previous examples, a sensor IP with several internal
 sensors used to monitor different zones, one of them is composed by several sensors and
 with different cooling devices.
+
+(e) Board thermal with stacked thermal zones
+
+Instead of setting up one thermal zone combining multiple thermal
+zones and multiple trip points for each cooling device, we can create
+a hierarchy of thermal zones.
+
+#include <dt-bindings/thermal/thermal.h>
+
+&i2c1 {
+	...
+	/*
+	 * An IC with several temperature sensor.
+	 */
+	adc_dummy: sensor@0x50 {
+		...
+		#thermal-sensor-cells = <1>; /* sensor internal ID */
+	};
+};
+
+thermal-zones {
+
+        cpu_thermal: cpu_thermal {
+		polling-delay-passive = <1000>; /* milliseconds */
+		polling-delay = <2500>; /* milliseconds */
+
+		sustainable-power = <2500>;
+
+		thermal-sensors = <&adc_dummy 0>
+
+		trips {
+			cpu_trip: cpu-trip {
+				temperature = <60000>; /* millicelsius */
+				hysteresis = <2000>; /* millicelsius */
+				type = "passive";
+			};
+                };
+
+		cooling-maps {
+			map0 {
+				trip = <&cpu_trip>;
+				cooling-device = <&cpu0 0 2>;
+			};
+                };
+        };
+
+        gpu_thermal: gpu_thermal {
+		polling-delay-passive = <1000>; /* milliseconds */
+		polling-delay = <2500>; /* milliseconds */
+
+		sustainable-power = <2500>;
+
+		thermal-sensors = <&adc_dummy 2>
+
+		trips {
+			gpu_trip: gpu-trip {
+				temperature = <55000>; /* millicelsius */
+				hysteresis = <2000>; /* millicelsius */
+				type = "passive";
+			}
+                };
+
+		cooling-maps {
+			map0 {
+				trip = <&gpu_trip>;
+				cooling-device = <&gpu0 0 2>;
+			};
+                };
+        };
+
+        lcd_thermal: lcd_thermal {
+		polling-delay-passive = <1000>; /* milliseconds */
+		polling-delay = <2500>; /* milliseconds */
+
+		sustainable-power = <2500>;
+
+		thermal-sensors = <&adc_dummy 1>
+
+		trips {
+			lcd_trip: lcp-trip {
+				temperature = <53000>; /* millicelsius */
+				hysteresis = <2000>; /* millicelsius */
+				type = "passive";
+			};
+                };
+
+		cooling-maps {
+			map0 {
+				trip = <&lcd_trip>;
+				cooling-device = <&lcd0 5 10>;
+			};
+                };
+        };
+
+	board_thermal: board-thermal {
+		polling-delay-passive = <1000>; /* milliseconds */
+		polling-delay = <2500>; /* milliseconds */
+
+		thermal-sensors = <&cpu_thermal &gpu_thermal &lcd_thermal>
+
+		sustainable-power = <2500>;
+
+		trips {
+			warm_trip: warm-trip {
+				temperature = <62000>; /* millicelsius */
+				hysteresis = <2000>; /* millicelsius */
+				type = "passive";
+			};
+			crit_trip: crit-trip {
+				temperature = <68000>; /* millicelsius */
+				hysteresis = <2000>; /* millicelsius */
+				type = "critical";
+			};
+		};
+
+		cooling-maps {
+			map0 {
+				trip = <&warm_trip>;
+				cooling-device = <&cpu0 2 2>;
+				contribution = <55>;
+			};
+			map1 {
+				trip = <&warm_trip>;
+				cooling-device = <&gpu0 2 2>;
+				contribution = <20>;
+			};
+			map2 {
+				trip = <&lcd_trip>;
+				cooling-device = <&lcd0 7 10>;
+				contribution = <15>;
+			};
+		};
+	};
+};
+
+The above example is a different take at example (d).  We create one
+thermal zone per sensor: cpu_thermal, gpu_thermal and lcd_thermal.
+Each of which has its own trip point for each own cooling device.  We
+then define a board_thermal thermal zone that is a combination of all
+the other thermal zones.  If the board hits its warm_trip, then all
+cooling devices are throttled.
+
+This example illustrates how we can throttle each device individually
+if its too hot and at the same time have some control over the whole
+system.
diff --git a/drivers/thermal/of-thermal.c b/drivers/thermal/of-thermal.c
index 42b7d4253b94..d0431f6058bd 100644
--- a/drivers/thermal/of-thermal.c
+++ b/drivers/thermal/of-thermal.c
@@ -166,6 +166,26 @@ of_thermal_get_trip_points(struct thermal_zone_device *tz)
 EXPORT_SYMBOL_GPL(of_thermal_get_trip_points);
 
 /**
+ * of_thermal_is_thermal_zone() - check that a device node corresponds to a thermal zone
+ * @np:	the device node
+ *
+ * Valid thermal zone device nodes must provide the
+ * polling-delay-passive and polling-delay properties.  If this device
+ * node provides them return true, as it's a valid device node for a
+ * thermal zone.
+ */
+static bool of_thermal_is_thermal_zone(struct device_node *np)
+{
+	u32 out;
+
+	if ((of_property_read_u32(np, "polling-delay-passive", &out)) ||
+	    (of_property_read_u32(np, "polling-delay", &out)))
+		return false;
+
+	return true;
+}
+
+/**
  * of_thermal_set_emul_temp - function to set emulated temperature
  *
  * @tz:	pointer to a thermal zone
@@ -858,6 +878,81 @@ static inline void of_thermal_free_zone(struct __thermal_zone *tz)
 }
 
 /**
+ * link_stacked_thermal_zones() - link thermal zones that are a superset of thermal zones
+ * @np:	device node for the root of the thermal zones
+ *
+ * A thermal zone can specify other thermal zones as its input using
+ * the thermal-sensors property of device tree.  This function parses
+ * all the thermal zones in dt and adds the thermal zones in their
+ * thermal-sensors as sub-thermalzones.
+ */
+static void link_stacked_thermal_zones(struct device_node *np)
+{
+	struct device_node *child;
+
+	for_each_child_of_node(np, child) {
+		int i, num_sensors;
+		struct thermal_zone_device *tz;
+
+		num_sensors = of_count_phandle_with_args(child,
+							 "thermal-sensors",
+							 "#thermal-sensor-cells");
+		if (num_sensors <= 0)
+			continue;
+
+		tz = thermal_zone_get_zone_by_name(child->name);
+		if (IS_ERR_OR_NULL(tz)) {
+			/*
+			 * If the tz is available we should have added
+			 * it in of_parse_thermal_zones()
+			 */
+			WARN(of_device_is_available(child),
+			     "Couldn't find thermal zone for %s\n",
+			     of_node_full_name(child));
+			continue;
+		}
+
+		for (i = 0; i < num_sensors; i++) {
+			struct of_phandle_args sensor_specs;
+			struct thermal_zone_device *subtz;
+			int ret;
+
+			ret = of_parse_phandle_with_args(child,
+							"thermal-sensors",
+							"#thermal-sensor-cells",
+							i, &sensor_specs);
+			if (ret) {
+				pr_warn("Failed to parse thermal-sensors of %s: %d\n",
+					of_node_full_name(child), ret);
+				of_node_put(sensor_specs.np);
+				continue;
+			}
+
+			if (!of_thermal_is_thermal_zone(sensor_specs.np)) {
+				of_node_put(sensor_specs.np);
+				continue;
+			}
+
+			subtz = thermal_zone_get_zone_by_name(
+				sensor_specs.np->name);
+			if (IS_ERR_OR_NULL(subtz)) {
+				pr_warn("Couldn't find thermal zone for %s, is it disabled?\n",
+					of_node_full_name(sensor_specs.np));
+				of_node_put(sensor_specs.np);
+				continue;
+			}
+
+			ret = thermal_zone_add_subtz(tz, subtz);
+			if (ret)
+				pr_warn("Failed to add thermal zone %s to %s: %d\n",
+					subtz->type, tz->type, ret);
+
+			of_node_put(sensor_specs.np);
+		}
+	}
+}
+
+/**
  * of_parse_thermal_zones - parse device tree thermal data
  *
  * Initialization function that can be called by machine initialization
@@ -936,6 +1031,9 @@ int __init of_parse_thermal_zones(void)
 			/* attempting to build remaining zones still */
 		}
 	}
+
+	link_stacked_thermal_zones(np);
+
 	of_node_put(np);
 
 	return 0;
-- 
1.9.1

[PATCH 3/3] thermal: show the sub thermal zones in sysfs

[Javi Merino]

When a thermal zone is created that has sub thermal zones via
devicetree or via thermal_zone_add_subtz() expose that relationship in
sysfs.

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 |  5 +++++
 drivers/thermal/thermal_core.c      | 22 ++++++++++++++++++++++
 include/linux/thermal.h             |  3 +++
 3 files changed, 30 insertions(+)

diff --git a/Documentation/thermal/sysfs-api.txt b/Documentation/thermal/sysfs-api.txt
index 5650b7eaaf7e..53972973792a 100644
--- a/Documentation/thermal/sysfs-api.txt
+++ b/Documentation/thermal/sysfs-api.txt
@@ -220,6 +220,7 @@ 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
+    |---subtz[0-*]              Slave thermal zones of this thermal zone
     |---sustainable_power:      Sustainable dissipatable power
     |---k_po:                   Proportional term during temperature overshoot
     |---k_pu:                   Proportional term during temperature undershoot
@@ -355,6 +356,10 @@ emul_temp
 	  because userland can easily disable the thermal policy by simply
 	  flooding this sysfs node with low temperature values.
 
+subtz[0-*]
+	sysfs link to the slave thermal zone device.
+        RO, Optional
+
 sustainable_power
 	An estimate of the sustained power that can be dissipated by
 	the thermal zone. Used by the power allocator governor. For
diff --git a/drivers/thermal/thermal_core.c b/drivers/thermal/thermal_core.c
index a2ab482337f3..af72b704af36 100644
--- a/drivers/thermal/thermal_core.c
+++ b/drivers/thermal/thermal_core.c
@@ -62,6 +62,8 @@ static DEFINE_MUTEX(thermal_governor_lock);
 static struct thermal_governor *def_governor;
 
 struct thermal_zone_link {
+	int id;
+	char name[THERMAL_NAME_LENGTH];
 	struct thermal_zone_device *slave;
 	struct list_head node;
 };
@@ -2076,6 +2078,23 @@ int thermal_zone_add_subtz(struct thermal_zone_device *tz,
 	link->slave = subtz;
 	list_add_tail(&link->node, &tz->slave_tzs);
 
+	ret = get_idr(&tz->link_idr, NULL, &link->id);
+	if (ret) {
+		/*
+		 * Even if we couldn't create the symlink in sysfs,
+		 * we've linked the thermal zones, so return success
+		 */
+		ret = 0;
+		goto unlock;
+	}
+
+	snprintf(link->name, ARRAY_SIZE(link->name), "subtz%d", link->id);
+	ret = sysfs_create_link(&tz->device.kobj, &subtz->device.kobj,
+				link->name);
+	if (ret)
+		pr_warn("Failed to create symlink to sub thermal zone: %d\n",
+			ret);
+
 	ret = 0;
 
 unlock:
@@ -2107,6 +2126,9 @@ int thermal_zone_del_subtz(struct thermal_zone_device *tz,
 
 	list_for_each_entry(link, &tz->slave_tzs, node) {
 		if (link->slave == subtz) {
+			sysfs_remove_link(&tz->device.kobj, link->name);
+			release_idr(&tz->link_idr, NULL, link->id);
+
 			list_del(&link->node);
 			kfree(link);
 
diff --git a/include/linux/thermal.h b/include/linux/thermal.h
index 7996b4e7e61a..c5ca3be8b7ec 100644
--- a/include/linux/thermal.h
+++ b/include/linux/thermal.h
@@ -174,6 +174,8 @@ struct thermal_attr {
  * @thermal_instances:	list of &struct thermal_instance of this thermal zone
  * @idr:	&struct idr to generate unique id for this zone's cooling
  *		devices
+ * @link_idr:	&struct idr to generate unique ids for this zone's links to
+ *		other thermal zones
  * @lock:	lock to protect thermal_instances list
  * @node:	node in thermal_tz_list (in thermal_core.c)
  * @poll_queue:	delayed work for polling
@@ -202,6 +204,7 @@ struct thermal_zone_device {
 	void *governor_data;
 	struct list_head thermal_instances;
 	struct idr idr;
+	struct idr link_idr;
 	struct mutex lock;
 	struct list_head node;
 	struct delayed_work poll_queue;
-- 
1.9.1

Re: [PATCH 1/3] thermal: Add support for hierarchical thermal zones

[kbuild test robot]

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Hi Javi,

[auto build test WARNING on thermal/next -- if it's inappropriate base, please suggest rules for selecting the more suitable base]

url:    https://github.com/0day-ci/linux/commits/Javi-Merino/Hierarchical-thermal-zones/20151031-005118
config: m32r-m32104ut_defconfig (attached as .config)
reproduce:
        wget https://git.kernel.org/cgit/linux/kernel/git/wfg/lkp-tests.git/plain/sbin/make.cross -O ~/bin/make.cross
        chmod +x ~/bin/make.cross
        # save the attached .config to linux build tree
        make.cross ARCH=m32r 

All warnings (new ones prefixed by >>):

   In file included from drivers/hwmon/lm75.c:31:0:
   include/linux/thermal.h: In function 'thermal_zone_add_subtz':
>> include/linux/thermal.h:471:3: warning: return makes pointer from integer without a cast
    { return -ENODEV; }
      ^
   include/linux/thermal.h: In function 'thermal_zone_del_subtz':
   include/linux/thermal.h:475:3: warning: return makes pointer from integer without a cast
    { return -ENODEV; }
      ^

vim +471 include/linux/thermal.h

   455	static inline void thermal_zone_device_update(struct thermal_zone_device *tz)
   456	{ }
   457	static inline struct thermal_cooling_device *
   458	thermal_cooling_device_register(char *type, void *devdata,
   459		const struct thermal_cooling_device_ops *ops)
   460	{ return ERR_PTR(-ENODEV); }
   461	static inline struct thermal_cooling_device *
   462	thermal_of_cooling_device_register(struct device_node *np,
   463		char *type, void *devdata, const struct thermal_cooling_device_ops *ops)
   464	{ return ERR_PTR(-ENODEV); }
   465	static inline void thermal_cooling_device_unregister(
   466		struct thermal_cooling_device *cdev)
   467	{ }
   468	static inline struct thermal_zone_device *
   469	thermal_zone_add_subtz(struct thermal_zone_device *tz,
   470			       struct thermal_zone_device *subtz)
 > 471	{ return -ENODEV; }
   472	static inline struct thermal_zone_device *
   473	thermal_zone_del_subtz(struct thermal_zone_device *tz,
   474			       struct thermal_zone_device *subtz)
   475	{ return -ENODEV; }
   476	static inline struct thermal_zone_device *thermal_zone_get_zone_by_name(
   477			const char *name)
   478	{ return ERR_PTR(-ENODEV); }
   479	static inline int thermal_zone_get_temp(

---
0-DAY kernel test infrastructure                Open Source Technology Center
https://lists.01.org/pipermail/kbuild-all                   Intel Corporation

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