[RFC v3 00/12] PM: SoC idle support using PM domains

[RFC v3 00/12] PM: SoC idle support using PM domains

[Lina Iyer]

Hi all,

Changes since RFC v2 [6] -
- Bug fix for NULL callbacks
- Address review comments from Stephen

Changes since RFC v1 [1] -
- genpd lock abstraction using fn ptrs. Sparse is happier.
- Removed restriction that IRQ-safe domains can only have IRQ safe parents [3]
- changes in the way CPU domains are initialized, starting from CPU now
	* cpu-map node dependency removed
	* platform driver initiate CPU PM domain setup
- smaller patchset excluding genpd multiple level changes
	* they were submitted to ML earlier [2]
- cpuidle runtime PM and hotplug changes
- PSCI changes to detect if the f/w supports OSI
- updated documentation
- this new cover description

This series allows CPU common hardware blocks to enter idle state, when the
CPUs are in idle. A lightweight but important power saving in a battery powered
device is power savings when the device is not suspended. While being active,
the CPUs can save power by entering low power states with the help of cpuidle
framework, but the hardware supporting these CPU still remain active. This is
an effort in reducing power on these h/w block around the CPU during cpuidle.

Every CPU decides for itself the deepest low power mode possible and enters
that state to be more power effecient. This is unlike coupled states, where
CPUs have to wait until the last of the CPU is ready to enter the deepest idle.
The last of the CPU that enters idle decides for the domain, the best idle
state the domain may enter. This is also a higher level than what MCPM solves.
In newer SoC's the coherency and other race conditions coming out of warm reset
are handled in the firmware. This patchset helps Linux make the right power
decision for other h/w blocks that are dependent on the CPUs.

The idea is that CPU hierarchy (represented in DT) is modelled as regular
devices attached to their PM domains, which in turn may be attached to its
parent domain. When cpuidle puts the CPU to sleep, runtime PM for the CPU
device is notified, which suspends the CPU device. This triggers a reduction in
genpd domain usage count. When the last device in a domain suspends, the domain
is powered off as part of the same call. Similarly, the domain resumes before
the first CPU device resumes from idle. To achieve this the following changes
are needed -
	- genpd to support multiple idle states (more than just on/off)
	- genpd should support suspend/resume from IRQ safe context
	- CPU devices set up for runtime PM, as IRQ safe devices
	- cpuidle calls runtime PM ops when idling
	- the genpd power downs calling into a gov to determine the deepest idle state 
	- genpd ->power_on()/->power_off() callbacks to be handled by the platform

Patches from Axel [2] allow genpd to define multiple idle states and choose the
best idle state from them.

These patches build up on top of that -

- Patches [1, 2] - Genpd changes
Sets up Generic PM domains to be called from cpuidle. Genpd uses mutexes for
synchronization. This has to be changed to spinlocks for domains that may be
called from IRQ safe contexts.

- Patch [3] - CPU PM domains
Parses DT and sets up PM domains for CPUs and builds up the hierarchy of
domains and devices. These are bunch of helper functions.

- Patch [4] - ARM cpuidle driver
Enable ARM cpuidle driver to call runtime PM. Even though this has been done
for ARM, there is nothing architecture specific about this. Currently, all idle
states other than ARM clock gating calls into runtime PM. This could also be
state specific i.e call into runtime PM only after a certain state. The changes
may be made part of cpuidle framework, but needs discussion.

- Patches [5, 6, 7] - PM domain governor for CPUs
Introduces a new genpd governor that looks into the per-CPU tick device to
identify the next CPU wakeup and determine the available sleep time for the
domain. This along with QoS is used to determine the best idle state for the
domain. A domains' wake up is determined by the first CPU in that domain to
wake up. A coherency level domain's (parent of a domain containing CPU devices)
wake up is determined by the first CPU amongst all the CPUs to wake up.
Identifying the CPUs and their wakeups are the part of these patches.

- Patches [9, 10] - ARM64 PSCI platform driver
ARM64 PSCI v1.0 specific. PSCI OS initiated mode supports powering off CPU
clusters (caches etc, by configuring separate power controllers). These patches
enable Linux to determine if the f/w supports this mode and if so, uses CPU PM
domain helper functions to create PM domains and handles the power_on/power_off
callbacks. The resulting cluster state is passed as an argument to the f/w
along with the CPU state.

- Patches [11, 12] - DTS changes for MSM8916
QCOM 410c Dragonboard/96Board specific. Enables CPUidle and cluster idle for
this SoC. A compatible f/w (in the works) is needed for this support.

Testing and results -

This patchset has been tested on a QCOM 410c Dragonboard with a quad ARM v8 A53
CPU and 512KB L2 cache. Though not accurate, I see a ~20 mA drop in current
measured at the battery outside the SoC when the SoC idle is enabled. This
needs to be redone again to get an accurate measurement. I see about ~5 us
increase before entering idle state to determine the last man down and about
~20 us while coming out of idle (in Linux) when the cache is flushed and
powered down.

This was tested on top of 4.5-rc3. My series along with patches from Axel can
be found at [4]. Note that [5] has not been published on the ML, is needed for
this series.

Thanks,
Lina

[1]. http://comments.gmane.org/gmane.linux.ports.arm.msm/16232
[2]. http://permalink.gmane.org/gmane.linux.power-management.general/71387
[3]. http://permalink.gmane.org/gmane.linux.ports.arm.msm/17279
[4]. https://git.linaro.org/people/lina.iyer/linux-next.git/shortlog/refs/heads/genpd-psci-RFC-v3
[5]. https://git.linaro.org/people/lina.iyer/linux-next.git/commit/1dfec82c8c133b0fbcd245d739dade087a1dd1fc
[6]. https://lwn.net/Articles/675674/


Lina Iyer (12):
  PM / Domains: Abstract genpd locking
  PM / Domains: Support IRQ safe PM domains
  PM / cpu_domains: Setup PM domains for CPUs/clusters
  ARM: cpuidle: Add runtime PM support for CPUs
  timer: Export next wake up of a CPU
  PM / cpu_domains: Record CPUs that are part of the domain
  PM / cpu_domains: Add PM Domain governor for CPUs
  Documentation / cpu_domains: Describe CPU PM domains setup and
    governor
  drivers: firmware: psci: Allow OS Initiated suspend mode
  ARM64: psci: Support cluster idle states for OS-Initiated
  ARM64: dts: Add PSCI cpuidle support for MSM8916
  ARM64: dts: Define CPU power domain for MSM8916

 Documentation/power/cpu_domains.txt   |  79 ++++++++
 Documentation/power/devices.txt       |  12 +-
 arch/arm64/boot/dts/qcom/msm8916.dtsi |  49 +++++
 arch/arm64/kernel/psci.c              |  46 ++++-
 drivers/base/power/Makefile           |   1 +
 drivers/base/power/cpu_domains.c      | 365 ++++++++++++++++++++++++++++++++++
 drivers/base/power/domain.c           | 210 +++++++++++++++----
 drivers/cpuidle/cpuidle-arm.c         |  55 +++++
 drivers/firmware/psci.c               |  45 ++++-
 include/linux/cpu_domains.h           |  37 ++++
 include/linux/pm_domain.h             |  14 +-
 include/linux/psci.h                  |   2 +
 include/linux/tick.h                  |  10 +
 include/uapi/linux/psci.h             |   5 +
 kernel/time/tick-sched.c              |  13 ++
 15 files changed, 896 insertions(+), 47 deletions(-)
 create mode 100644 Documentation/power/cpu_domains.txt
 create mode 100644 drivers/base/power/cpu_domains.c
 create mode 100644 include/linux/cpu_domains.h

-- 
2.1.4

[RFC v3 00/12] PM: SoC idle support using PM domains

[Lina Iyer]

Hi all,

Changes since RFC v2 [6] -
- Bug fix for NULL callbacks
- Address review comments from Stephen

Changes since RFC v1 [1] -
- genpd lock abstraction using fn ptrs. Sparse is happier.
- Removed restriction that IRQ-safe domains can only have IRQ safe parents [3]
- changes in the way CPU domains are initialized, starting from CPU now
	* cpu-map node dependency removed
	* platform driver initiate CPU PM domain setup
- smaller patchset excluding genpd multiple level changes
	* they were submitted to ML earlier [2]
- cpuidle runtime PM and hotplug changes
- PSCI changes to detect if the f/w supports OSI
- updated documentation
- this new cover description

This series allows CPU common hardware blocks to enter idle state, when the
CPUs are in idle. A lightweight but important power saving in a battery powered
device is power savings when the device is not suspended. While being active,
the CPUs can save power by entering low power states with the help of cpuidle
framework, but the hardware supporting these CPU still remain active. This is
an effort in reducing power on these h/w block around the CPU during cpuidle.

Every CPU decides for itself the deepest low power mode possible and enters
that state to be more power effecient. This is unlike coupled states, where
CPUs have to wait until the last of the CPU is ready to enter the deepest idle.
The last of the CPU that enters idle decides for the domain, the best idle
state the domain may enter. This is also a higher level than what MCPM solves.
In newer SoC's the coherency and other race conditions coming out of warm reset
are handled in the firmware. This patchset helps Linux make the right power
decision for other h/w blocks that are dependent on the CPUs.

The idea is that CPU hierarchy (represented in DT) is modelled as regular
devices attached to their PM domains, which in turn may be attached to its
parent domain. When cpuidle puts the CPU to sleep, runtime PM for the CPU
device is notified, which suspends the CPU device. This triggers a reduction in
genpd domain usage count. When the last device in a domain suspends, the domain
is powered off as part of the same call. Similarly, the domain resumes before
the first CPU device resumes from idle. To achieve this the following changes
are needed -
	- genpd to support multiple idle states (more than just on/off)
	- genpd should support suspend/resume from IRQ safe context
	- CPU devices set up for runtime PM, as IRQ safe devices
	- cpuidle calls runtime PM ops when idling
	- the genpd power downs calling into a gov to determine the deepest idle state 
	- genpd ->power_on()/->power_off() callbacks to be handled by the platform

Patches from Axel [2] allow genpd to define multiple idle states and choose the
best idle state from them.

These patches build up on top of that -

- Patches [1, 2] - Genpd changes
Sets up Generic PM domains to be called from cpuidle. Genpd uses mutexes for
synchronization. This has to be changed to spinlocks for domains that may be
called from IRQ safe contexts.

- Patch [3] - CPU PM domains
Parses DT and sets up PM domains for CPUs and builds up the hierarchy of
domains and devices. These are bunch of helper functions.

- Patch [4] - ARM cpuidle driver
Enable ARM cpuidle driver to call runtime PM. Even though this has been done
for ARM, there is nothing architecture specific about this. Currently, all idle
states other than ARM clock gating calls into runtime PM. This could also be
state specific i.e call into runtime PM only after a certain state. The changes
may be made part of cpuidle framework, but needs discussion.

- Patches [5, 6, 7] - PM domain governor for CPUs
Introduces a new genpd governor that looks into the per-CPU tick device to
identify the next CPU wakeup and determine the available sleep time for the
domain. This along with QoS is used to determine the best idle state for the
domain. A domains' wake up is determined by the first CPU in that domain to
wake up. A coherency level domain's (parent of a domain containing CPU devices)
wake up is determined by the first CPU amongst all the CPUs to wake up.
Identifying the CPUs and their wakeups are the part of these patches.

- Patches [9, 10] - ARM64 PSCI platform driver
ARM64 PSCI v1.0 specific. PSCI OS initiated mode supports powering off CPU
clusters (caches etc, by configuring separate power controllers). These patches
enable Linux to determine if the f/w supports this mode and if so, uses CPU PM
domain helper functions to create PM domains and handles the power_on/power_off
callbacks. The resulting cluster state is passed as an argument to the f/w
along with the CPU state.

- Patches [11, 12] - DTS changes for MSM8916
QCOM 410c Dragonboard/96Board specific. Enables CPUidle and cluster idle for
this SoC. A compatible f/w (in the works) is needed for this support.

Testing and results -

This patchset has been tested on a QCOM 410c Dragonboard with a quad ARM v8 A53
CPU and 512KB L2 cache. Though not accurate, I see a ~20 mA drop in current
measured at the battery outside the SoC when the SoC idle is enabled. This
needs to be redone again to get an accurate measurement. I see about ~5 us
increase before entering idle state to determine the last man down and about
~20 us while coming out of idle (in Linux) when the cache is flushed and
powered down.

This was tested on top of 4.5-rc3. My series along with patches from Axel can
be found at [4]. Note that [5] has not been published on the ML, is needed for
this series.

Thanks,
Lina

[1]. http://comments.gmane.org/gmane.linux.ports.arm.msm/16232
[2]. http://permalink.gmane.org/gmane.linux.power-management.general/71387
[3]. http://permalink.gmane.org/gmane.linux.ports.arm.msm/17279
[4]. https://git.linaro.org/people/lina.iyer/linux-next.git/shortlog/refs/heads/genpd-psci-RFC-v3
[5]. https://git.linaro.org/people/lina.iyer/linux-next.git/commit/1dfec82c8c133b0fbcd245d739dade087a1dd1fc
[6]. https://lwn.net/Articles/675674/


Lina Iyer (12):
  PM / Domains: Abstract genpd locking
  PM / Domains: Support IRQ safe PM domains
  PM / cpu_domains: Setup PM domains for CPUs/clusters
  ARM: cpuidle: Add runtime PM support for CPUs
  timer: Export next wake up of a CPU
  PM / cpu_domains: Record CPUs that are part of the domain
  PM / cpu_domains: Add PM Domain governor for CPUs
  Documentation / cpu_domains: Describe CPU PM domains setup and
    governor
  drivers: firmware: psci: Allow OS Initiated suspend mode
  ARM64: psci: Support cluster idle states for OS-Initiated
  ARM64: dts: Add PSCI cpuidle support for MSM8916
  ARM64: dts: Define CPU power domain for MSM8916

 Documentation/power/cpu_domains.txt   |  79 ++++++++
 Documentation/power/devices.txt       |  12 +-
 arch/arm64/boot/dts/qcom/msm8916.dtsi |  49 +++++
 arch/arm64/kernel/psci.c              |  46 ++++-
 drivers/base/power/Makefile           |   1 +
 drivers/base/power/cpu_domains.c      | 365 ++++++++++++++++++++++++++++++++++
 drivers/base/power/domain.c           | 210 +++++++++++++++----
 drivers/cpuidle/cpuidle-arm.c         |  55 +++++
 drivers/firmware/psci.c               |  45 ++++-
 include/linux/cpu_domains.h           |  37 ++++
 include/linux/pm_domain.h             |  14 +-
 include/linux/psci.h                  |   2 +
 include/linux/tick.h                  |  10 +
 include/uapi/linux/psci.h             |   5 +
 kernel/time/tick-sched.c              |  13 ++
 15 files changed, 896 insertions(+), 47 deletions(-)
 create mode 100644 Documentation/power/cpu_domains.txt
 create mode 100644 drivers/base/power/cpu_domains.c
 create mode 100644 include/linux/cpu_domains.h

-- 
2.1.4

[BUG FIX] PM / cpu_domains: Check for NULL callbacks

[Lina Iyer]

Check for NULL platform callback before calling.

Signed-off-by: Lina Iyer <lina.iyer@linaro.org>
---
 drivers/base/power/cpu_domains.c | 10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/drivers/base/power/cpu_domains.c b/drivers/base/power/cpu_domains.c
index 7069411..bcaa474 100644
--- a/drivers/base/power/cpu_domains.c
+++ b/drivers/base/power/cpu_domains.c
@@ -157,16 +157,22 @@ static int cpu_pd_power_on(struct generic_pm_domain *genpd)
 {
 	struct cpu_pm_domain *pd = to_cpu_pd(genpd);
 
-	return pd->ops.power_on();
+	if (pd->ops.power_on)
+		return pd->ops.power_on();
+
+	return 0;
 }
 
 static int cpu_pd_power_off(struct generic_pm_domain *genpd)
 {
 	struct cpu_pm_domain *pd = to_cpu_pd(genpd);
 
-	return pd->ops.power_off(genpd->state_idx,
+	if (pd->ops.power_off)
+		return pd->ops.power_off(genpd->state_idx,
 			genpd->states[genpd->state_idx].param,
 			pd->cpus);
+
+	return 0;
 }
 
 /**
-- 
2.1.4

[BUG FIX] PM / cpu_domains: Check for NULL callbacks

[Lina Iyer]

Check for NULL platform callback before calling.

Signed-off-by: Lina Iyer <lina.iyer@linaro.org>
---
 drivers/base/power/cpu_domains.c | 10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/drivers/base/power/cpu_domains.c b/drivers/base/power/cpu_domains.c
index 7069411..bcaa474 100644
--- a/drivers/base/power/cpu_domains.c
+++ b/drivers/base/power/cpu_domains.c
@@ -157,16 +157,22 @@ static int cpu_pd_power_on(struct generic_pm_domain *genpd)
 {
 	struct cpu_pm_domain *pd = to_cpu_pd(genpd);
 
-	return pd->ops.power_on();
+	if (pd->ops.power_on)
+		return pd->ops.power_on();
+
+	return 0;
 }
 
 static int cpu_pd_power_off(struct generic_pm_domain *genpd)
 {
 	struct cpu_pm_domain *pd = to_cpu_pd(genpd);
 
-	return pd->ops.power_off(genpd->state_idx,
+	if (pd->ops.power_off)
+		return pd->ops.power_off(genpd->state_idx,
 			genpd->states[genpd->state_idx].param,
 			pd->cpus);
+
+	return 0;
 }
 
 /**
-- 
2.1.4

[RFC v3 01/12] PM / Domains: Abstract genpd locking

[Lina Iyer]

Abstract genpd lock/unlock calls, in preparation for domain specific
locks added in the following patches.

Cc: Ulf Hansson <ulf.hansson@linaro.org>
Cc: Kevin Hilman <khilman@linaro.org>
Cc: Rafael J. Wysocki <rjw@rjwysocki.net>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Krzysztof Kozłowski <k.kozlowski@samsung.com>
Signed-off-by: Lina Iyer <lina.iyer@linaro.org>
---
 drivers/base/power/domain.c | 109 ++++++++++++++++++++++++++++++--------------
 include/linux/pm_domain.h   |   5 +-
 2 files changed, 79 insertions(+), 35 deletions(-)

diff --git a/drivers/base/power/domain.c b/drivers/base/power/domain.c
index 3ddd05d..20533d9 100644
--- a/drivers/base/power/domain.c
+++ b/drivers/base/power/domain.c
@@ -40,6 +40,46 @@
 static LIST_HEAD(gpd_list);
 static DEFINE_MUTEX(gpd_list_lock);
 
+struct genpd_lock_fns {
+	void (*lock)(struct generic_pm_domain *genpd);
+	void (*lock_nested)(struct generic_pm_domain *genpd, int depth);
+	int (*lock_interruptible)(struct generic_pm_domain *genpd);
+	void (*unlock)(struct generic_pm_domain *genpd);
+};
+
+static void genpd_lock_mtx(struct generic_pm_domain *genpd)
+{
+	mutex_lock(&genpd->mlock);
+}
+
+static void genpd_lock_nested_mtx(struct generic_pm_domain *genpd,
+					int depth)
+{
+	mutex_lock_nested(&genpd->mlock, depth);
+}
+
+static int genpd_lock_interruptible_mtx(struct generic_pm_domain *genpd)
+{
+	return mutex_lock_interruptible(&genpd->mlock);
+}
+
+static void genpd_unlock_mtx(struct generic_pm_domain *genpd)
+{
+	return mutex_unlock(&genpd->mlock);
+}
+
+static const struct genpd_lock_fns genpd_mtx_fns  = {
+	.lock = genpd_lock_mtx,
+	.lock_nested = genpd_lock_nested_mtx,
+	.lock_interruptible = genpd_lock_interruptible_mtx,
+	.unlock = genpd_unlock_mtx,
+};
+
+#define genpd_lock(p)			p->lock_fns->lock(p)
+#define genpd_lock_nested(p, d)		p->lock_fns->lock_nested(p, d)
+#define genpd_lock_interruptible(p)	p->lock_fns->lock_interruptible(p)
+#define genpd_unlock(p)			p->lock_fns->unlock(p)
+
 /*
  * Get the generic PM domain for a particular struct device.
  * This validates the struct device pointer, the PM domain pointer,
@@ -202,9 +242,9 @@ static int genpd_poweron(struct generic_pm_domain *genpd, unsigned int depth)
 
 		genpd_sd_counter_inc(master);
 
-		mutex_lock_nested(&master->lock, depth + 1);
+		genpd_lock_nested(master, depth + 1);
 		ret = genpd_poweron(master, depth + 1);
-		mutex_unlock(&master->lock);
+		genpd_unlock(master);
 
 		if (ret) {
 			genpd_sd_counter_dec(master);
@@ -268,9 +308,9 @@ static int genpd_dev_pm_qos_notifier(struct notifier_block *nb,
 		spin_unlock_irq(&dev->power.lock);
 
 		if (!IS_ERR(genpd)) {
-			mutex_lock(&genpd->lock);
+			genpd_lock(genpd);
 			genpd->max_off_time_changed = true;
-			mutex_unlock(&genpd->lock);
+			genpd_unlock(genpd);
 		}
 
 		dev = dev->parent;
@@ -367,9 +407,9 @@ static void genpd_power_off_work_fn(struct work_struct *work)
 
 	genpd = container_of(work, struct generic_pm_domain, power_off_work);
 
-	mutex_lock(&genpd->lock);
+	genpd_lock(genpd);
 	genpd_poweroff(genpd, true);
-	mutex_unlock(&genpd->lock);
+	genpd_unlock(genpd);
 }
 
 /**
@@ -439,9 +479,9 @@ static int pm_genpd_runtime_suspend(struct device *dev)
 	if (dev->power.irq_safe)
 		return 0;
 
-	mutex_lock(&genpd->lock);
+	genpd_lock(genpd);
 	genpd_poweroff(genpd, false);
-	mutex_unlock(&genpd->lock);
+	genpd_unlock(genpd);
 
 	return 0;
 }
@@ -476,9 +516,9 @@ static int pm_genpd_runtime_resume(struct device *dev)
 		goto out;
 	}
 
-	mutex_lock(&genpd->lock);
+	genpd_lock(genpd);
 	ret = genpd_poweron(genpd, 0);
-	mutex_unlock(&genpd->lock);
+	genpd_unlock(genpd);
 
 	if (ret)
 		return ret;
@@ -692,14 +732,14 @@ static int pm_genpd_prepare(struct device *dev)
 	if (resume_needed(dev, genpd))
 		pm_runtime_resume(dev);
 
-	mutex_lock(&genpd->lock);
+	genpd_lock(genpd);
 
 	if (genpd->prepared_count++ == 0) {
 		genpd->suspended_count = 0;
 		genpd->suspend_power_off = genpd->status == GPD_STATE_POWER_OFF;
 	}
 
-	mutex_unlock(&genpd->lock);
+	genpd_unlock(genpd);
 
 	if (genpd->suspend_power_off) {
 		pm_runtime_put_noidle(dev);
@@ -717,12 +757,12 @@ static int pm_genpd_prepare(struct device *dev)
 
 	ret = pm_generic_prepare(dev);
 	if (ret) {
-		mutex_lock(&genpd->lock);
+		genpd_lock(genpd);
 
 		if (--genpd->prepared_count == 0)
 			genpd->suspend_power_off = false;
 
-		mutex_unlock(&genpd->lock);
+		genpd_unlock(genpd);
 		pm_runtime_enable(dev);
 	}
 
@@ -1080,13 +1120,13 @@ static void pm_genpd_complete(struct device *dev)
 	if (IS_ERR(genpd))
 		return;
 
-	mutex_lock(&genpd->lock);
+	genpd_lock(genpd);
 
 	run_complete = !genpd->suspend_power_off;
 	if (--genpd->prepared_count == 0)
 		genpd->suspend_power_off = false;
 
-	mutex_unlock(&genpd->lock);
+	genpd_unlock(genpd);
 
 	if (run_complete) {
 		pm_generic_complete(dev);
@@ -1260,7 +1300,7 @@ int __pm_genpd_add_device(struct generic_pm_domain *genpd, struct device *dev,
 	if (IS_ERR(gpd_data))
 		return PTR_ERR(gpd_data);
 
-	mutex_lock(&genpd->lock);
+	genpd_lock(genpd);
 
 	if (genpd->prepared_count > 0) {
 		ret = -EAGAIN;
@@ -1277,7 +1317,7 @@ int __pm_genpd_add_device(struct generic_pm_domain *genpd, struct device *dev,
 	list_add_tail(&gpd_data->base.list_node, &genpd->dev_list);
 
  out:
-	mutex_unlock(&genpd->lock);
+	genpd_unlock(genpd);
 
 	if (ret)
 		genpd_free_dev_data(dev, gpd_data);
@@ -1310,7 +1350,7 @@ int pm_genpd_remove_device(struct generic_pm_domain *genpd,
 	gpd_data = to_gpd_data(pdd);
 	dev_pm_qos_remove_notifier(dev, &gpd_data->nb);
 
-	mutex_lock(&genpd->lock);
+	genpd_lock(genpd);
 
 	if (genpd->prepared_count > 0) {
 		ret = -EAGAIN;
@@ -1325,14 +1365,14 @@ int pm_genpd_remove_device(struct generic_pm_domain *genpd,
 
 	list_del_init(&pdd->list_node);
 
-	mutex_unlock(&genpd->lock);
+	genpd_unlock(genpd);
 
 	genpd_free_dev_data(dev, gpd_data);
 
 	return 0;
 
  out:
-	mutex_unlock(&genpd->lock);
+	genpd_unlock(genpd);
 	dev_pm_qos_add_notifier(dev, &gpd_data->nb);
 
 	return ret;
@@ -1358,8 +1398,8 @@ int pm_genpd_add_subdomain(struct generic_pm_domain *genpd,
 	if (!link)
 		return -ENOMEM;
 
-	mutex_lock(&subdomain->lock);
-	mutex_lock_nested(&genpd->lock, SINGLE_DEPTH_NESTING);
+	genpd_lock(subdomain);
+	genpd_lock_nested(genpd, SINGLE_DEPTH_NESTING);
 
 	if (genpd->status == GPD_STATE_POWER_OFF
 	    &&  subdomain->status != GPD_STATE_POWER_OFF) {
@@ -1382,8 +1422,8 @@ int pm_genpd_add_subdomain(struct generic_pm_domain *genpd,
 		genpd_sd_counter_inc(genpd);
 
  out:
-	mutex_unlock(&genpd->lock);
-	mutex_unlock(&subdomain->lock);
+	genpd_unlock(genpd);
+	genpd_unlock(subdomain);
 	if (ret)
 		kfree(link);
 	return ret;
@@ -1404,8 +1444,8 @@ int pm_genpd_remove_subdomain(struct generic_pm_domain *genpd,
 	if (IS_ERR_OR_NULL(genpd) || IS_ERR_OR_NULL(subdomain))
 		return -EINVAL;
 
-	mutex_lock(&subdomain->lock);
-	mutex_lock_nested(&genpd->lock, SINGLE_DEPTH_NESTING);
+	genpd_lock(subdomain);
+	genpd_lock_nested(genpd, SINGLE_DEPTH_NESTING);
 
 	if (!list_empty(&subdomain->slave_links) || subdomain->device_count) {
 		pr_warn("%s: unable to remove subdomain %s\n", genpd->name,
@@ -1429,8 +1469,8 @@ int pm_genpd_remove_subdomain(struct generic_pm_domain *genpd,
 	}
 
 out:
-	mutex_unlock(&genpd->lock);
-	mutex_unlock(&subdomain->lock);
+	genpd_unlock(genpd);
+	genpd_unlock(subdomain);
 
 	return ret;
 }
@@ -1595,7 +1635,8 @@ void pm_genpd_init(struct generic_pm_domain *genpd,
 	INIT_LIST_HEAD(&genpd->master_links);
 	INIT_LIST_HEAD(&genpd->slave_links);
 	INIT_LIST_HEAD(&genpd->dev_list);
-	mutex_init(&genpd->lock);
+	mutex_init(&genpd->mlock);
+	genpd->lock_fns = &genpd_mtx_fns;
 	genpd->gov = gov;
 	INIT_WORK(&genpd->power_off_work, genpd_power_off_work_fn);
 	atomic_set(&genpd->sd_count, 0);
@@ -1952,9 +1993,9 @@ int genpd_dev_pm_attach(struct device *dev)
 	dev->pm_domain->detach = genpd_dev_pm_detach;
 	dev->pm_domain->sync = genpd_dev_pm_sync;
 
-	mutex_lock(&pd->lock);
+	genpd_lock(pd);
 	ret = genpd_poweron(pd, 0);
-	mutex_unlock(&pd->lock);
+	genpd_unlock(pd);
 out:
 	return ret ? -EPROBE_DEFER : 0;
 }
@@ -2011,7 +2052,7 @@ static int pm_genpd_summary_one(struct seq_file *s,
 	struct gpd_link *link;
 	int ret;
 
-	ret = mutex_lock_interruptible(&genpd->lock);
+	ret = genpd_lock_interruptible(genpd);
 	if (ret)
 		return -ERESTARTSYS;
 
@@ -2047,7 +2088,7 @@ static int pm_genpd_summary_one(struct seq_file *s,
 
 	seq_puts(s, "\n");
 exit:
-	mutex_unlock(&genpd->lock);
+	genpd_unlock(genpd);
 
 	return 0;
 }
diff --git a/include/linux/pm_domain.h b/include/linux/pm_domain.h
index 376d7fa..6bebc56 100644
--- a/include/linux/pm_domain.h
+++ b/include/linux/pm_domain.h
@@ -44,13 +44,14 @@ struct genpd_power_state {
 	u32 param;
 };
 
+struct genpd_lock_fns;
+
 struct generic_pm_domain {
 	struct dev_pm_domain domain;	/* PM domain operations */
 	struct list_head gpd_list_node;	/* Node in the global PM domains list */
 	struct list_head master_links;	/* Links with PM domain as a master */
 	struct list_head slave_links;	/* Links with PM domain as a slave */
 	struct list_head dev_list;	/* List of devices */
-	struct mutex lock;
 	struct dev_power_governor *gov;
 	struct work_struct power_off_work;
 	const char *name;
@@ -74,6 +75,8 @@ struct generic_pm_domain {
 	struct genpd_power_state *states;
 	unsigned int state_count; /* number of states */
 	unsigned int state_idx; /* state that genpd will go to when off */
+	const struct genpd_lock_fns *lock_fns;
+	struct mutex mlock;
 
 };
 
-- 
2.1.4

[RFC v3 01/12] PM / Domains: Abstract genpd locking

[Lina Iyer]

Abstract genpd lock/unlock calls, in preparation for domain specific
locks added in the following patches.

Cc: Ulf Hansson <ulf.hansson@linaro.org>
Cc: Kevin Hilman <khilman@linaro.org>
Cc: Rafael J. Wysocki <rjw@rjwysocki.net>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Krzysztof Koz?owski <k.kozlowski@samsung.com>
Signed-off-by: Lina Iyer <lina.iyer@linaro.org>
---
 drivers/base/power/domain.c | 109 ++++++++++++++++++++++++++++++--------------
 include/linux/pm_domain.h   |   5 +-
 2 files changed, 79 insertions(+), 35 deletions(-)

diff --git a/drivers/base/power/domain.c b/drivers/base/power/domain.c
index 3ddd05d..20533d9 100644
--- a/drivers/base/power/domain.c
+++ b/drivers/base/power/domain.c
@@ -40,6 +40,46 @@
 static LIST_HEAD(gpd_list);
 static DEFINE_MUTEX(gpd_list_lock);
 
+struct genpd_lock_fns {
+	void (*lock)(struct generic_pm_domain *genpd);
+	void (*lock_nested)(struct generic_pm_domain *genpd, int depth);
+	int (*lock_interruptible)(struct generic_pm_domain *genpd);
+	void (*unlock)(struct generic_pm_domain *genpd);
+};
+
+static void genpd_lock_mtx(struct generic_pm_domain *genpd)
+{
+	mutex_lock(&genpd->mlock);
+}
+
+static void genpd_lock_nested_mtx(struct generic_pm_domain *genpd,
+					int depth)
+{
+	mutex_lock_nested(&genpd->mlock, depth);
+}
+
+static int genpd_lock_interruptible_mtx(struct generic_pm_domain *genpd)
+{
+	return mutex_lock_interruptible(&genpd->mlock);
+}
+
+static void genpd_unlock_mtx(struct generic_pm_domain *genpd)
+{
+	return mutex_unlock(&genpd->mlock);
+}
+
+static const struct genpd_lock_fns genpd_mtx_fns  = {
+	.lock = genpd_lock_mtx,
+	.lock_nested = genpd_lock_nested_mtx,
+	.lock_interruptible = genpd_lock_interruptible_mtx,
+	.unlock = genpd_unlock_mtx,
+};
+
+#define genpd_lock(p)			p->lock_fns->lock(p)
+#define genpd_lock_nested(p, d)		p->lock_fns->lock_nested(p, d)
+#define genpd_lock_interruptible(p)	p->lock_fns->lock_interruptible(p)
+#define genpd_unlock(p)			p->lock_fns->unlock(p)
+
 /*
  * Get the generic PM domain for a particular struct device.
  * This validates the struct device pointer, the PM domain pointer,
@@ -202,9 +242,9 @@ static int genpd_poweron(struct generic_pm_domain *genpd, unsigned int depth)
 
 		genpd_sd_counter_inc(master);
 
-		mutex_lock_nested(&master->lock, depth + 1);
+		genpd_lock_nested(master, depth + 1);
 		ret = genpd_poweron(master, depth + 1);
-		mutex_unlock(&master->lock);
+		genpd_unlock(master);
 
 		if (ret) {
 			genpd_sd_counter_dec(master);
@@ -268,9 +308,9 @@ static int genpd_dev_pm_qos_notifier(struct notifier_block *nb,
 		spin_unlock_irq(&dev->power.lock);
 
 		if (!IS_ERR(genpd)) {
-			mutex_lock(&genpd->lock);
+			genpd_lock(genpd);
 			genpd->max_off_time_changed = true;
-			mutex_unlock(&genpd->lock);
+			genpd_unlock(genpd);
 		}
 
 		dev = dev->parent;
@@ -367,9 +407,9 @@ static void genpd_power_off_work_fn(struct work_struct *work)
 
 	genpd = container_of(work, struct generic_pm_domain, power_off_work);
 
-	mutex_lock(&genpd->lock);
+	genpd_lock(genpd);
 	genpd_poweroff(genpd, true);
-	mutex_unlock(&genpd->lock);
+	genpd_unlock(genpd);
 }
 
 /**
@@ -439,9 +479,9 @@ static int pm_genpd_runtime_suspend(struct device *dev)
 	if (dev->power.irq_safe)
 		return 0;
 
-	mutex_lock(&genpd->lock);
+	genpd_lock(genpd);
 	genpd_poweroff(genpd, false);
-	mutex_unlock(&genpd->lock);
+	genpd_unlock(genpd);
 
 	return 0;
 }
@@ -476,9 +516,9 @@ static int pm_genpd_runtime_resume(struct device *dev)
 		goto out;
 	}
 
-	mutex_lock(&genpd->lock);
+	genpd_lock(genpd);
 	ret = genpd_poweron(genpd, 0);
-	mutex_unlock(&genpd->lock);
+	genpd_unlock(genpd);
 
 	if (ret)
 		return ret;
@@ -692,14 +732,14 @@ static int pm_genpd_prepare(struct device *dev)
 	if (resume_needed(dev, genpd))
 		pm_runtime_resume(dev);
 
-	mutex_lock(&genpd->lock);
+	genpd_lock(genpd);
 
 	if (genpd->prepared_count++ == 0) {
 		genpd->suspended_count = 0;
 		genpd->suspend_power_off = genpd->status == GPD_STATE_POWER_OFF;
 	}
 
-	mutex_unlock(&genpd->lock);
+	genpd_unlock(genpd);
 
 	if (genpd->suspend_power_off) {
 		pm_runtime_put_noidle(dev);
@@ -717,12 +757,12 @@ static int pm_genpd_prepare(struct device *dev)
 
 	ret = pm_generic_prepare(dev);
 	if (ret) {
-		mutex_lock(&genpd->lock);
+		genpd_lock(genpd);
 
 		if (--genpd->prepared_count == 0)
 			genpd->suspend_power_off = false;
 
-		mutex_unlock(&genpd->lock);
+		genpd_unlock(genpd);
 		pm_runtime_enable(dev);
 	}
 
@@ -1080,13 +1120,13 @@ static void pm_genpd_complete(struct device *dev)
 	if (IS_ERR(genpd))
 		return;
 
-	mutex_lock(&genpd->lock);
+	genpd_lock(genpd);
 
 	run_complete = !genpd->suspend_power_off;
 	if (--genpd->prepared_count == 0)
 		genpd->suspend_power_off = false;
 
-	mutex_unlock(&genpd->lock);
+	genpd_unlock(genpd);
 
 	if (run_complete) {
 		pm_generic_complete(dev);
@@ -1260,7 +1300,7 @@ int __pm_genpd_add_device(struct generic_pm_domain *genpd, struct device *dev,
 	if (IS_ERR(gpd_data))
 		return PTR_ERR(gpd_data);
 
-	mutex_lock(&genpd->lock);
+	genpd_lock(genpd);
 
 	if (genpd->prepared_count > 0) {
 		ret = -EAGAIN;
@@ -1277,7 +1317,7 @@ int __pm_genpd_add_device(struct generic_pm_domain *genpd, struct device *dev,
 	list_add_tail(&gpd_data->base.list_node, &genpd->dev_list);
 
  out:
-	mutex_unlock(&genpd->lock);
+	genpd_unlock(genpd);
 
 	if (ret)
 		genpd_free_dev_data(dev, gpd_data);
@@ -1310,7 +1350,7 @@ int pm_genpd_remove_device(struct generic_pm_domain *genpd,
 	gpd_data = to_gpd_data(pdd);
 	dev_pm_qos_remove_notifier(dev, &gpd_data->nb);
 
-	mutex_lock(&genpd->lock);
+	genpd_lock(genpd);
 
 	if (genpd->prepared_count > 0) {
 		ret = -EAGAIN;
@@ -1325,14 +1365,14 @@ int pm_genpd_remove_device(struct generic_pm_domain *genpd,
 
 	list_del_init(&pdd->list_node);
 
-	mutex_unlock(&genpd->lock);
+	genpd_unlock(genpd);
 
 	genpd_free_dev_data(dev, gpd_data);
 
 	return 0;
 
  out:
-	mutex_unlock(&genpd->lock);
+	genpd_unlock(genpd);
 	dev_pm_qos_add_notifier(dev, &gpd_data->nb);
 
 	return ret;
@@ -1358,8 +1398,8 @@ int pm_genpd_add_subdomain(struct generic_pm_domain *genpd,
 	if (!link)
 		return -ENOMEM;
 
-	mutex_lock(&subdomain->lock);
-	mutex_lock_nested(&genpd->lock, SINGLE_DEPTH_NESTING);
+	genpd_lock(subdomain);
+	genpd_lock_nested(genpd, SINGLE_DEPTH_NESTING);
 
 	if (genpd->status == GPD_STATE_POWER_OFF
 	    &&  subdomain->status != GPD_STATE_POWER_OFF) {
@@ -1382,8 +1422,8 @@ int pm_genpd_add_subdomain(struct generic_pm_domain *genpd,
 		genpd_sd_counter_inc(genpd);
 
  out:
-	mutex_unlock(&genpd->lock);
-	mutex_unlock(&subdomain->lock);
+	genpd_unlock(genpd);
+	genpd_unlock(subdomain);
 	if (ret)
 		kfree(link);
 	return ret;
@@ -1404,8 +1444,8 @@ int pm_genpd_remove_subdomain(struct generic_pm_domain *genpd,
 	if (IS_ERR_OR_NULL(genpd) || IS_ERR_OR_NULL(subdomain))
 		return -EINVAL;
 
-	mutex_lock(&subdomain->lock);
-	mutex_lock_nested(&genpd->lock, SINGLE_DEPTH_NESTING);
+	genpd_lock(subdomain);
+	genpd_lock_nested(genpd, SINGLE_DEPTH_NESTING);
 
 	if (!list_empty(&subdomain->slave_links) || subdomain->device_count) {
 		pr_warn("%s: unable to remove subdomain %s\n", genpd->name,
@@ -1429,8 +1469,8 @@ int pm_genpd_remove_subdomain(struct generic_pm_domain *genpd,
 	}
 
 out:
-	mutex_unlock(&genpd->lock);
-	mutex_unlock(&subdomain->lock);
+	genpd_unlock(genpd);
+	genpd_unlock(subdomain);
 
 	return ret;
 }
@@ -1595,7 +1635,8 @@ void pm_genpd_init(struct generic_pm_domain *genpd,
 	INIT_LIST_HEAD(&genpd->master_links);
 	INIT_LIST_HEAD(&genpd->slave_links);
 	INIT_LIST_HEAD(&genpd->dev_list);
-	mutex_init(&genpd->lock);
+	mutex_init(&genpd->mlock);
+	genpd->lock_fns = &genpd_mtx_fns;
 	genpd->gov = gov;
 	INIT_WORK(&genpd->power_off_work, genpd_power_off_work_fn);
 	atomic_set(&genpd->sd_count, 0);
@@ -1952,9 +1993,9 @@ int genpd_dev_pm_attach(struct device *dev)
 	dev->pm_domain->detach = genpd_dev_pm_detach;
 	dev->pm_domain->sync = genpd_dev_pm_sync;
 
-	mutex_lock(&pd->lock);
+	genpd_lock(pd);
 	ret = genpd_poweron(pd, 0);
-	mutex_unlock(&pd->lock);
+	genpd_unlock(pd);
 out:
 	return ret ? -EPROBE_DEFER : 0;
 }
@@ -2011,7 +2052,7 @@ static int pm_genpd_summary_one(struct seq_file *s,
 	struct gpd_link *link;
 	int ret;
 
-	ret = mutex_lock_interruptible(&genpd->lock);
+	ret = genpd_lock_interruptible(genpd);
 	if (ret)
 		return -ERESTARTSYS;
 
@@ -2047,7 +2088,7 @@ static int pm_genpd_summary_one(struct seq_file *s,
 
 	seq_puts(s, "\n");
 exit:
-	mutex_unlock(&genpd->lock);
+	genpd_unlock(genpd);
 
 	return 0;
 }
diff --git a/include/linux/pm_domain.h b/include/linux/pm_domain.h
index 376d7fa..6bebc56 100644
--- a/include/linux/pm_domain.h
+++ b/include/linux/pm_domain.h
@@ -44,13 +44,14 @@ struct genpd_power_state {
 	u32 param;
 };
 
+struct genpd_lock_fns;
+
 struct generic_pm_domain {
 	struct dev_pm_domain domain;	/* PM domain operations */
 	struct list_head gpd_list_node;	/* Node in the global PM domains list */
 	struct list_head master_links;	/* Links with PM domain as a master */
 	struct list_head slave_links;	/* Links with PM domain as a slave */
 	struct list_head dev_list;	/* List of devices */
-	struct mutex lock;
 	struct dev_power_governor *gov;
 	struct work_struct power_off_work;
 	const char *name;
@@ -74,6 +75,8 @@ struct generic_pm_domain {
 	struct genpd_power_state *states;
 	unsigned int state_count; /* number of states */
 	unsigned int state_idx; /* state that genpd will go to when off */
+	const struct genpd_lock_fns *lock_fns;
+	struct mutex mlock;
 
 };
 
-- 
2.1.4

[RFC v3 02/12] PM / Domains: Support IRQ safe PM domains

[Lina Iyer]

Generic Power Domains currently support turning on/off only in process
context. This prevents the usage of PM domains for domains that could be
powered on/off in a context where IRQs are disabled. Many such domains
exist today and do not get powered off, when the IRQ safe devices in
that domain are powered off, because of this limitation.

However, not all domains can operate in IRQ safe contexts. Genpd
therefore, has to support both cases where the domain may or may not
operate in IRQ safe contexts. Configuring genpd to use an appropriate
lock for that domain, would allow domains that have IRQ safe devices to
runtime suspend and resume, in atomic context.

To achieve domain specific locking, set the domain's ->flag to
GENPD_FLAG_IRQ_SAFE while defining the domain. This indicates that genpd
should use a spinlock instead of a mutex for locking the domain. Locking
is abstracted through genpd_lock() and genpd_unlock() functions that use
the flag to determine the appropriate lock to be used for that domain.

Domains that have lower latency to suspend and resume and can operate
with IRQs disabled may now be able to save power, when the component
devices and sub-domains are idle at runtime.

The restriction this imposes on the domain hierarchy is that non-IRQ
safe domains may not have IRQ-safe subdomains, but IRQ safe domains may
have IRQ safe and non-IRQ safe domains and devices.

Cc: Ulf Hansson <ulf.hansson@linaro.org>
Cc: Kevin Hilman <khilman@linaro.org>
Cc: Rafael J. Wysocki <rjw@rjwysocki.net>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Krzysztof Kozłowski <k.kozlowski@samsung.com>
Signed-off-by: Lina Iyer <lina.iyer@linaro.org>
---
 Documentation/power/devices.txt |  12 ++++-
 drivers/base/power/domain.c     | 105 ++++++++++++++++++++++++++++++++++++----
 include/linux/pm_domain.h       |  11 ++++-
 3 files changed, 117 insertions(+), 11 deletions(-)

diff --git a/Documentation/power/devices.txt b/Documentation/power/devices.txt
index 8ba6625..a622136 100644
--- a/Documentation/power/devices.txt
+++ b/Documentation/power/devices.txt
@@ -607,7 +607,17 @@ individually.  Instead, a set of devices sharing a power resource can be put
 into a low-power state together at the same time by turning off the shared
 power resource.  Of course, they also need to be put into the full-power state
 together, by turning the shared power resource on.  A set of devices with this
-property is often referred to as a power domain.
+property is often referred to as a power domain. A power domain may also be
+nested inside another power domain.
+
+Devices, by default, operate in process context. If a device can operate in
+IRQ safe context that has to be explicitly indicated by setting the irq_safe
+boolean inside struct generic_pm_domain to be true. Power domains by default,
+operate in process context but could have devices that are IRQ safe. Such
+power domains cannot be powered on/off during runtime PM. On the other hand,
+IRQ safe PM domains that have IRQ safe devices may be powered off when all
+the devices are in idle. An IRQ safe domain may only be attached as a
+subdomain to another IRQ safe domain.
 
 Support for power domains is provided through the pm_domain field of struct
 device.  This field is a pointer to an object of type struct dev_pm_domain,
diff --git a/drivers/base/power/domain.c b/drivers/base/power/domain.c
index 20533d9..9541d80 100644
--- a/drivers/base/power/domain.c
+++ b/drivers/base/power/domain.c
@@ -75,11 +75,59 @@ static const struct genpd_lock_fns genpd_mtx_fns  = {
 	.unlock = genpd_unlock_mtx,
 };
 
+static void genpd_lock_spin(struct generic_pm_domain *genpd)
+	__acquires(&genpd->slock)
+{
+	unsigned long flags;
+
+	spin_lock_irqsave(&genpd->slock, flags);
+	genpd->lock_flags = flags;
+}
+
+static void genpd_lock_nested_spin(struct generic_pm_domain *genpd,
+					int depth)
+	__acquires(&genpd->slock)
+{
+	unsigned long flags;
+
+	spin_lock_irqsave_nested(&genpd->slock, flags, depth);
+	genpd->lock_flags = flags;
+}
+
+static int genpd_lock_interruptible_spin(struct generic_pm_domain *genpd)
+	__acquires(&genpd->slock)
+{
+	unsigned long flags;
+
+	spin_lock_irqsave(&genpd->slock, flags);
+	genpd->lock_flags = flags;
+	return 0;
+}
+
+static void genpd_unlock_spin(struct generic_pm_domain *genpd)
+	__releases(&genpd->slock)
+{
+	spin_unlock_irqrestore(&genpd->slock, genpd->lock_flags);
+}
+
+static const struct genpd_lock_fns genpd_spin_fns = {
+	.lock = genpd_lock_spin,
+	.lock_nested = genpd_lock_nested_spin,
+	.lock_interruptible = genpd_lock_interruptible_spin,
+	.unlock = genpd_unlock_spin,
+};
+
 #define genpd_lock(p)			p->lock_fns->lock(p)
 #define genpd_lock_nested(p, d)		p->lock_fns->lock_nested(p, d)
 #define genpd_lock_interruptible(p)	p->lock_fns->lock_interruptible(p)
 #define genpd_unlock(p)			p->lock_fns->unlock(p)
 
+static inline bool irq_safe_dev_in_no_sleep_domain(struct device *dev,
+		struct generic_pm_domain *genpd)
+{
+	return dev->power.irq_safe && !genpd->irq_safe;
+}
+
 /*
  * Get the generic PM domain for a particular struct device.
  * This validates the struct device pointer, the PM domain pointer,
@@ -356,8 +404,17 @@ static int genpd_poweroff(struct generic_pm_domain *genpd, bool is_async)
 		if (stat > PM_QOS_FLAGS_NONE)
 			return -EBUSY;
 
-		if (!pm_runtime_suspended(pdd->dev) || pdd->dev->power.irq_safe)
+		/*
+		 * We do not want to power off the domain if the device is
+		 * not suspended or an IRQ safe device is part of this
+		 * non-IRQ safe domain.
+		 */
+		if (!pm_runtime_suspended(pdd->dev) ||
+			irq_safe_dev_in_no_sleep_domain(pdd->dev, genpd))
 			not_suspended++;
+		WARN_ONCE(irq_safe_dev_in_no_sleep_domain(pdd->dev, genpd),
+				"PM domain %s will not be powered off\n",
+				genpd->name);
 	}
 
 	if (not_suspended > 1 || (not_suspended == 1 && is_async))
@@ -473,10 +530,13 @@ static int pm_genpd_runtime_suspend(struct device *dev)
 	}
 
 	/*
-	 * If power.irq_safe is set, this routine will be run with interrupts
-	 * off, so it can't use mutexes.
+	 * If power.irq_safe is set, this routine may be run with
+	 * IRQ disabled, so suspend only if the power domain is
+	 * irq_safe.
 	 */
-	if (dev->power.irq_safe)
+	WARN_ONCE(irq_safe_dev_in_no_sleep_domain(dev, genpd),
+			"genpd %s will not be powered off\n", genpd->name);
+	if (irq_safe_dev_in_no_sleep_domain(dev, genpd))
 		return 0;
 
 	genpd_lock(genpd);
@@ -510,8 +570,11 @@ static int pm_genpd_runtime_resume(struct device *dev)
 	if (IS_ERR(genpd))
 		return -EINVAL;
 
-	/* If power.irq_safe, the PM domain is never powered off. */
-	if (dev->power.irq_safe) {
+	/*
+	 * As we don't power off a non IRQ safe domain, which holds
+	 * an IRQ safe device, we don't need to restore power to it.
+	 */
+	if (dev->power.irq_safe && !genpd->irq_safe) {
 		timed = false;
 		goto out;
 	}
@@ -1394,6 +1457,17 @@ int pm_genpd_add_subdomain(struct generic_pm_domain *genpd,
 	    || genpd == subdomain)
 		return -EINVAL;
 
+	/*
+	 * If the domain can be powered on/off in an IRQ safe
+	 * context, ensure that the subdomain can also be
+	 * powered on/off in that context.
+	 */
+	if (!genpd->irq_safe && subdomain->irq_safe) {
+		WARN("Parent %s of subdomain %s must be IRQ safe\n",
+				genpd->name, subdomain->name);
+		return -EINVAL;
+	}
+
 	link = kzalloc(sizeof(*link), GFP_KERNEL);
 	if (!link)
 		return -ENOMEM;
@@ -1610,6 +1684,19 @@ static int of_genpd_device_parse_states(struct device_node *np,
 	return 0;
 }
 
+static void genpd_lock_init(struct generic_pm_domain *genpd)
+{
+	if (genpd->flags & GENPD_FLAG_IRQ_SAFE) {
+		spin_lock_init(&genpd->slock);
+		genpd->irq_safe = true;
+		genpd->lock_fns = &genpd_spin_fns;
+	} else {
+		mutex_init(&genpd->mlock);
+		genpd->irq_safe = false;
+		genpd->lock_fns = &genpd_mtx_fns;
+	}
+}
+
 /**
  * pm_genpd_init - Initialize a generic I/O PM domain object.
  * @genpd: PM domain object to initialize.
@@ -1635,8 +1722,7 @@ void pm_genpd_init(struct generic_pm_domain *genpd,
 	INIT_LIST_HEAD(&genpd->master_links);
 	INIT_LIST_HEAD(&genpd->slave_links);
 	INIT_LIST_HEAD(&genpd->dev_list);
-	mutex_init(&genpd->mlock);
-	genpd->lock_fns = &genpd_mtx_fns;
+	genpd_lock_init(genpd);
 	genpd->gov = gov;
 	INIT_WORK(&genpd->power_off_work, genpd_power_off_work_fn);
 	atomic_set(&genpd->sd_count, 0);
@@ -2077,7 +2163,8 @@ static int pm_genpd_summary_one(struct seq_file *s,
 	}
 
 	list_for_each_entry(pm_data, &genpd->dev_list, list_node) {
-		kobj_path = kobject_get_path(&pm_data->dev->kobj, GFP_KERNEL);
+		kobj_path = kobject_get_path(&pm_data->dev->kobj,
+				genpd->irq_safe ? GFP_ATOMIC : GFP_KERNEL);
 		if (kobj_path == NULL)
 			continue;
 
diff --git a/include/linux/pm_domain.h b/include/linux/pm_domain.h
index 6bebc56..0091282 100644
--- a/include/linux/pm_domain.h
+++ b/include/linux/pm_domain.h
@@ -15,9 +15,11 @@
 #include <linux/err.h>
 #include <linux/of.h>
 #include <linux/notifier.h>
+#include <linux/spinlock.h>
 
 /* Defines used for the flags field in the struct generic_pm_domain */
 #define GENPD_FLAG_PM_CLK	(1U << 0) /* PM domain uses PM clk */
+#define GENPD_FLAG_IRQ_SAFE	(1U << 1) /* PM domain operates in atomic */
 
 enum gpd_status {
 	GPD_STATE_ACTIVE = 0,	/* PM domain is active */
@@ -76,7 +78,14 @@ struct generic_pm_domain {
 	unsigned int state_count; /* number of states */
 	unsigned int state_idx; /* state that genpd will go to when off */
 	const struct genpd_lock_fns *lock_fns;
-	struct mutex mlock;
+	bool irq_safe;
+	union {
+		struct mutex mlock;
+		struct {
+			spinlock_t slock;
+			unsigned long lock_flags;
+		};
+	};
 
 };
 
-- 
2.1.4

[RFC v3 02/12] PM / Domains: Support IRQ safe PM domains

[Lina Iyer]

Generic Power Domains currently support turning on/off only in process
context. This prevents the usage of PM domains for domains that could be
powered on/off in a context where IRQs are disabled. Many such domains
exist today and do not get powered off, when the IRQ safe devices in
that domain are powered off, because of this limitation.

However, not all domains can operate in IRQ safe contexts. Genpd
therefore, has to support both cases where the domain may or may not
operate in IRQ safe contexts. Configuring genpd to use an appropriate
lock for that domain, would allow domains that have IRQ safe devices to
runtime suspend and resume, in atomic context.

To achieve domain specific locking, set the domain's ->flag to
GENPD_FLAG_IRQ_SAFE while defining the domain. This indicates that genpd
should use a spinlock instead of a mutex for locking the domain. Locking
is abstracted through genpd_lock() and genpd_unlock() functions that use
the flag to determine the appropriate lock to be used for that domain.

Domains that have lower latency to suspend and resume and can operate
with IRQs disabled may now be able to save power, when the component
devices and sub-domains are idle at runtime.

The restriction this imposes on the domain hierarchy is that non-IRQ
safe domains may not have IRQ-safe subdomains, but IRQ safe domains may
have IRQ safe and non-IRQ safe domains and devices.

Cc: Ulf Hansson <ulf.hansson@linaro.org>
Cc: Kevin Hilman <khilman@linaro.org>
Cc: Rafael J. Wysocki <rjw@rjwysocki.net>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Krzysztof Koz?owski <k.kozlowski@samsung.com>
Signed-off-by: Lina Iyer <lina.iyer@linaro.org>
---
 Documentation/power/devices.txt |  12 ++++-
 drivers/base/power/domain.c     | 105 ++++++++++++++++++++++++++++++++++++----
 include/linux/pm_domain.h       |  11 ++++-
 3 files changed, 117 insertions(+), 11 deletions(-)

diff --git a/Documentation/power/devices.txt b/Documentation/power/devices.txt
index 8ba6625..a622136 100644
--- a/Documentation/power/devices.txt
+++ b/Documentation/power/devices.txt
@@ -607,7 +607,17 @@ individually.  Instead, a set of devices sharing a power resource can be put
 into a low-power state together at the same time by turning off the shared
 power resource.  Of course, they also need to be put into the full-power state
 together, by turning the shared power resource on.  A set of devices with this
-property is often referred to as a power domain.
+property is often referred to as a power domain. A power domain may also be
+nested inside another power domain.
+
+Devices, by default, operate in process context. If a device can operate in
+IRQ safe context that has to be explicitly indicated by setting the irq_safe
+boolean inside struct generic_pm_domain to be true. Power domains by default,
+operate in process context but could have devices that are IRQ safe. Such
+power domains cannot be powered on/off during runtime PM. On the other hand,
+IRQ safe PM domains that have IRQ safe devices may be powered off when all
+the devices are in idle. An IRQ safe domain may only be attached as a
+subdomain to another IRQ safe domain.
 
 Support for power domains is provided through the pm_domain field of struct
 device.  This field is a pointer to an object of type struct dev_pm_domain,
diff --git a/drivers/base/power/domain.c b/drivers/base/power/domain.c
index 20533d9..9541d80 100644
--- a/drivers/base/power/domain.c
+++ b/drivers/base/power/domain.c
@@ -75,11 +75,59 @@ static const struct genpd_lock_fns genpd_mtx_fns  = {
 	.unlock = genpd_unlock_mtx,
 };
 
+static void genpd_lock_spin(struct generic_pm_domain *genpd)
+	__acquires(&genpd->slock)
+{
+	unsigned long flags;
+
+	spin_lock_irqsave(&genpd->slock, flags);
+	genpd->lock_flags = flags;
+}
+
+static void genpd_lock_nested_spin(struct generic_pm_domain *genpd,
+					int depth)
+	__acquires(&genpd->slock)
+{
+	unsigned long flags;
+
+	spin_lock_irqsave_nested(&genpd->slock, flags, depth);
+	genpd->lock_flags = flags;
+}
+
+static int genpd_lock_interruptible_spin(struct generic_pm_domain *genpd)
+	__acquires(&genpd->slock)
+{
+	unsigned long flags;
+
+	spin_lock_irqsave(&genpd->slock, flags);
+	genpd->lock_flags = flags;
+	return 0;
+}
+
+static void genpd_unlock_spin(struct generic_pm_domain *genpd)
+	__releases(&genpd->slock)
+{
+	spin_unlock_irqrestore(&genpd->slock, genpd->lock_flags);
+}
+
+static const struct genpd_lock_fns genpd_spin_fns = {
+	.lock = genpd_lock_spin,
+	.lock_nested = genpd_lock_nested_spin,
+	.lock_interruptible = genpd_lock_interruptible_spin,
+	.unlock = genpd_unlock_spin,
+};
+
 #define genpd_lock(p)			p->lock_fns->lock(p)
 #define genpd_lock_nested(p, d)		p->lock_fns->lock_nested(p, d)
 #define genpd_lock_interruptible(p)	p->lock_fns->lock_interruptible(p)
 #define genpd_unlock(p)			p->lock_fns->unlock(p)
 
+static inline bool irq_safe_dev_in_no_sleep_domain(struct device *dev,
+		struct generic_pm_domain *genpd)
+{
+	return dev->power.irq_safe && !genpd->irq_safe;
+}
+
 /*
  * Get the generic PM domain for a particular struct device.
  * This validates the struct device pointer, the PM domain pointer,
@@ -356,8 +404,17 @@ static int genpd_poweroff(struct generic_pm_domain *genpd, bool is_async)
 		if (stat > PM_QOS_FLAGS_NONE)
 			return -EBUSY;
 
-		if (!pm_runtime_suspended(pdd->dev) || pdd->dev->power.irq_safe)
+		/*
+		 * We do not want to power off the domain if the device is
+		 * not suspended or an IRQ safe device is part of this
+		 * non-IRQ safe domain.
+		 */
+		if (!pm_runtime_suspended(pdd->dev) ||
+			irq_safe_dev_in_no_sleep_domain(pdd->dev, genpd))
 			not_suspended++;
+		WARN_ONCE(irq_safe_dev_in_no_sleep_domain(pdd->dev, genpd),
+				"PM domain %s will not be powered off\n",
+				genpd->name);
 	}
 
 	if (not_suspended > 1 || (not_suspended == 1 && is_async))
@@ -473,10 +530,13 @@ static int pm_genpd_runtime_suspend(struct device *dev)
 	}
 
 	/*
-	 * If power.irq_safe is set, this routine will be run with interrupts
-	 * off, so it can't use mutexes.
+	 * If power.irq_safe is set, this routine may be run with
+	 * IRQ disabled, so suspend only if the power domain is
+	 * irq_safe.
 	 */
-	if (dev->power.irq_safe)
+	WARN_ONCE(irq_safe_dev_in_no_sleep_domain(dev, genpd),
+			"genpd %s will not be powered off\n", genpd->name);
+	if (irq_safe_dev_in_no_sleep_domain(dev, genpd))
 		return 0;
 
 	genpd_lock(genpd);
@@ -510,8 +570,11 @@ static int pm_genpd_runtime_resume(struct device *dev)
 	if (IS_ERR(genpd))
 		return -EINVAL;
 
-	/* If power.irq_safe, the PM domain is never powered off. */
-	if (dev->power.irq_safe) {
+	/*
+	 * As we don't power off a non IRQ safe domain, which holds
+	 * an IRQ safe device, we don't need to restore power to it.
+	 */
+	if (dev->power.irq_safe && !genpd->irq_safe) {
 		timed = false;
 		goto out;
 	}
@@ -1394,6 +1457,17 @@ int pm_genpd_add_subdomain(struct generic_pm_domain *genpd,
 	    || genpd == subdomain)
 		return -EINVAL;
 
+	/*
+	 * If the domain can be powered on/off in an IRQ safe
+	 * context, ensure that the subdomain can also be
+	 * powered on/off in that context.
+	 */
+	if (!genpd->irq_safe && subdomain->irq_safe) {
+		WARN("Parent %s of subdomain %s must be IRQ safe\n",
+				genpd->name, subdomain->name);
+		return -EINVAL;
+	}
+
 	link = kzalloc(sizeof(*link), GFP_KERNEL);
 	if (!link)
 		return -ENOMEM;
@@ -1610,6 +1684,19 @@ static int of_genpd_device_parse_states(struct device_node *np,
 	return 0;
 }
 
+static void genpd_lock_init(struct generic_pm_domain *genpd)
+{
+	if (genpd->flags & GENPD_FLAG_IRQ_SAFE) {
+		spin_lock_init(&genpd->slock);
+		genpd->irq_safe = true;
+		genpd->lock_fns = &genpd_spin_fns;
+	} else {
+		mutex_init(&genpd->mlock);
+		genpd->irq_safe = false;
+		genpd->lock_fns = &genpd_mtx_fns;
+	}
+}
+
 /**
  * pm_genpd_init - Initialize a generic I/O PM domain object.
  * @genpd: PM domain object to initialize.
@@ -1635,8 +1722,7 @@ void pm_genpd_init(struct generic_pm_domain *genpd,
 	INIT_LIST_HEAD(&genpd->master_links);
 	INIT_LIST_HEAD(&genpd->slave_links);
 	INIT_LIST_HEAD(&genpd->dev_list);
-	mutex_init(&genpd->mlock);
-	genpd->lock_fns = &genpd_mtx_fns;
+	genpd_lock_init(genpd);
 	genpd->gov = gov;
 	INIT_WORK(&genpd->power_off_work, genpd_power_off_work_fn);
 	atomic_set(&genpd->sd_count, 0);
@@ -2077,7 +2163,8 @@ static int pm_genpd_summary_one(struct seq_file *s,
 	}
 
 	list_for_each_entry(pm_data, &genpd->dev_list, list_node) {
-		kobj_path = kobject_get_path(&pm_data->dev->kobj, GFP_KERNEL);
+		kobj_path = kobject_get_path(&pm_data->dev->kobj,
+				genpd->irq_safe ? GFP_ATOMIC : GFP_KERNEL);
 		if (kobj_path == NULL)
 			continue;
 
diff --git a/include/linux/pm_domain.h b/include/linux/pm_domain.h
index 6bebc56..0091282 100644
--- a/include/linux/pm_domain.h
+++ b/include/linux/pm_domain.h
@@ -15,9 +15,11 @@
 #include <linux/err.h>
 #include <linux/of.h>
 #include <linux/notifier.h>
+#include <linux/spinlock.h>
 
 /* Defines used for the flags field in the struct generic_pm_domain */
 #define GENPD_FLAG_PM_CLK	(1U << 0) /* PM domain uses PM clk */
+#define GENPD_FLAG_IRQ_SAFE	(1U << 1) /* PM domain operates in atomic */
 
 enum gpd_status {
 	GPD_STATE_ACTIVE = 0,	/* PM domain is active */
@@ -76,7 +78,14 @@ struct generic_pm_domain {
 	unsigned int state_count; /* number of states */
 	unsigned int state_idx; /* state that genpd will go to when off */
 	const struct genpd_lock_fns *lock_fns;
-	struct mutex mlock;
+	bool irq_safe;
+	union {
+		struct mutex mlock;
+		struct {
+			spinlock_t slock;
+			unsigned long lock_flags;
+		};
+	};
 
 };
 
-- 
2.1.4

[RFC v3 03/12] PM / cpu_domains: Setup PM domains for CPUs/clusters

[Lina Iyer]

Define and add Generic PM domains (genpd) for CPU clusters. Many new
SoCs group CPUs as clusters. Clusters share common resources like power
rails, caches, VFP, Coresight etc. When all CPUs in the cluster are
idle, these shared resources may also be put in their idle state.

CPUs may be associated with their domain providers in DT. The domains in
turn may be associated with their providers. This is clean way to model
the cluster hierarchy like that of ARM's big.little architecture.

For each CPU in the DT, we identify the domain provider; initialize and
register the PM domain if isn't already registered and attach all the
CPU devices to the domain. Usually, when there are multiple clusters of
CPUs, there is a top level coherency domain that is dependent on these
individual domains. All domains thus created are marked IRQ safe
automatically and therefore may be powered down when the CPUs in the
domain are powered down by cpuidle.

Reading DT, initializing Generic PM domains, attaching CPUs to it
domains are common functionalities across ARM SoCs. Provide a common set
of APIs to setup PM domains for CPU clusters and its parents. The
platform drivers may just call of_setup_cpu_pd() to do a single step
setup of CPU domains.

Cc: Ulf Hansson <ulf.hansson@linaro.org>
Cc: Daniel Lezcano <daniel.lezcano@linaro.org>
Cc: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Suggested-by: Kevin Hilman <khilman@linaro.org>
Signed-off-by: Lina Iyer <lina.iyer@linaro.org>
---
 drivers/base/power/Makefile      |   1 +
 drivers/base/power/cpu_domains.c | 267 +++++++++++++++++++++++++++++++++++++++
 include/linux/cpu_domains.h      |  35 +++++
 3 files changed, 303 insertions(+)
 create mode 100644 drivers/base/power/cpu_domains.c
 create mode 100644 include/linux/cpu_domains.h

diff --git a/drivers/base/power/Makefile b/drivers/base/power/Makefile
index 5998c53..9883e89 100644
--- a/drivers/base/power/Makefile
+++ b/drivers/base/power/Makefile
@@ -3,6 +3,7 @@ obj-$(CONFIG_PM_SLEEP)	+= main.o wakeup.o
 obj-$(CONFIG_PM_TRACE_RTC)	+= trace.o
 obj-$(CONFIG_PM_OPP)	+= opp/
 obj-$(CONFIG_PM_GENERIC_DOMAINS)	+=  domain.o domain_governor.o
+obj-$(CONFIG_PM_GENERIC_DOMAINS_OF)	+= cpu_domains.o
 obj-$(CONFIG_HAVE_CLK)	+= clock_ops.o
 
 ccflags-$(CONFIG_DEBUG_DRIVER) := -DDEBUG
diff --git a/drivers/base/power/cpu_domains.c b/drivers/base/power/cpu_domains.c
new file mode 100644
index 0000000..62704e6
--- /dev/null
+++ b/drivers/base/power/cpu_domains.c
@@ -0,0 +1,267 @@
+/*
+ * drivers/base/power/cpu_domains.c - Helper functions to create CPU PM domains.
+ *
+ * Copyright (C) 2016 Linaro 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.
+ */
+
+#include <linux/cpu.h>
+#include <linux/cpu_domains.h>
+#include <linux/cpu_pm.h>
+#include <linux/device.h>
+#include <linux/kernel.h>
+#include <linux/list.h>
+#include <linux/of.h>
+#include <linux/pm_domain.h>
+#include <linux/rculist.h>
+#include <linux/rcupdate.h>
+#include <linux/slab.h>
+
+#define CPU_PD_NAME_MAX 36
+
+struct cpu_pm_domain {
+	struct list_head link;
+	struct cpu_pd_ops ops;
+	struct generic_pm_domain *genpd;
+	struct cpu_pm_domain *parent;
+};
+
+/* List of CPU PM domains we care about */
+static LIST_HEAD(of_cpu_pd_list);
+static DEFINE_MUTEX(cpu_pd_list_lock);
+
+static inline
+struct cpu_pm_domain *to_cpu_pd(struct generic_pm_domain *d)
+{
+	struct cpu_pm_domain *pd;
+	struct cpu_pm_domain *res = NULL;
+
+	rcu_read_lock();
+	list_for_each_entry_rcu(pd, &of_cpu_pd_list, link)
+		if (pd->genpd == d) {
+			res = pd;
+			break;
+		}
+	rcu_read_unlock();
+
+	return res;
+}
+
+static int cpu_pd_attach_cpu(int cpu)
+{
+	int ret;
+	struct device *cpu_dev;
+
+	cpu_dev = get_cpu_device(cpu);
+	if (!cpu_dev) {
+		pr_warn("%s: Unable to get device for CPU%d\n",
+				__func__, cpu);
+		return -ENODEV;
+	}
+
+	ret = genpd_dev_pm_attach(cpu_dev);
+	if (ret)
+		dev_warn(cpu_dev,
+			"%s: Unable to attach to power-domain: %d\n",
+			__func__, ret);
+	else
+		dev_dbg(cpu_dev, "Attached to domain\n");
+
+	return ret;
+}
+
+static int cpu_pd_power_on(struct generic_pm_domain *genpd)
+{
+	struct cpu_pm_domain *pd = to_cpu_pd(genpd);
+
+	return pd->ops.power_on ? pd->ops.power_on() : 0;
+}
+
+static int cpu_pd_power_off(struct generic_pm_domain *genpd)
+{
+	struct cpu_pm_domain *pd = to_cpu_pd(genpd);
+
+	return pd->ops.power_off ? pd->ops.power_off(genpd->state_idx,
+					genpd->states[genpd->state_idx].param),
+					: 0;
+}
+
+/**
+ * of_init_cpu_pm_domain() - Initialize a CPU PM domain from a device node
+ *
+ * @dn: The domain provider's device node
+ * @ops: The power_on/_off callbacks for the domain
+ *
+ * Returns the generic_pm_domain (genpd) pointer to the domain on success
+ */
+static struct generic_pm_domain *of_init_cpu_pm_domain(struct device_node *dn,
+				const struct cpu_pd_ops *ops)
+{
+	struct cpu_pm_domain *pd = NULL;
+	struct generic_pm_domain *genpd = NULL;
+	int ret = -ENOMEM;
+
+	if (!of_device_is_available(dn))
+		return ERR_PTR(-ENODEV);
+
+	genpd = kzalloc(sizeof(*genpd), GFP_KERNEL);
+	if (!genpd)
+		goto fail;
+
+	genpd->name = kstrndup(dn->full_name, CPU_PD_NAME_MAX, GFP_KERNEL);
+	if (!genpd->name)
+		goto fail;
+
+	pd = kzalloc(sizeof(*pd), GFP_KERNEL);
+	if (!pd)
+		goto fail;
+
+	pd->genpd = genpd;
+	pd->genpd->power_off = cpu_pd_power_off;
+	pd->genpd->power_on = cpu_pd_power_on;
+	pd->genpd->flags |= GENPD_FLAG_IRQ_SAFE;
+	pd->ops.power_on = ops->power_on;
+	pd->ops.power_off = ops->power_off;
+
+	INIT_LIST_HEAD_RCU(&pd->link);
+	mutex_lock(&cpu_pd_list_lock);
+	list_add_rcu(&pd->link, &of_cpu_pd_list);
+	mutex_unlock(&cpu_pd_list_lock);
+
+	/* Register the CPU genpd */
+	pr_debug("adding %s as CPU PM domain\n", pd->genpd->name);
+	ret = of_pm_genpd_init(dn, pd->genpd, &simple_qos_governor, false);
+	if (ret) {
+		pr_err("Unable to initialize domain %s\n", dn->full_name);
+		goto fail;
+	}
+
+	ret = of_genpd_add_provider_simple(dn, pd->genpd);
+	if (ret)
+		pr_warn("Unable to add genpd %s as provider\n",
+				pd->genpd->name);
+
+	return pd->genpd;
+fail:
+
+	kfree(genpd->name);
+	kfree(genpd);
+	kfree(pd);
+	return ERR_PTR(ret);
+}
+
+static struct generic_pm_domain *of_get_cpu_domain(struct device_node *dn,
+		const struct cpu_pd_ops *ops, int cpu)
+{
+	struct of_phandle_args args;
+	struct generic_pm_domain *genpd, *parent;
+	struct cpu_pm_domain *cpu_pd, *parent_cpu_pd;
+	int ret;
+
+	/* Do we have this domain? If not, create the domain */
+	args.np = dn;
+	args.args_count = 0;
+
+	genpd = of_genpd_get_from_provider(&args);
+	if (!IS_ERR(genpd))
+		return genpd;
+
+	genpd = of_init_cpu_pm_domain(dn, ops);
+	if (IS_ERR(genpd))
+		return genpd;
+
+	/* Is there a domain provider for this domain? */
+	ret = of_parse_phandle_with_args(dn, "power-domains",
+			"#power-domain-cells", 0, &args);
+	if (ret < 0)
+		goto skip_parent;
+
+	/* Find its parent and attach this domain to it, recursively */
+	parent = of_get_cpu_domain(args.np, ops, cpu);
+	if (IS_ERR(parent))
+		goto skip_parent;
+
+	ret = pm_genpd_add_subdomain(genpd, parent);
+	if (ret) {
+		pr_err("%s: Unable to add sub-domain (%s)\n err: %d",
+				__func__, genpd->name, ret);
+		return ERR_PTR(ret);
+	}
+
+	/*
+	 * Reference parent domain for easy access.
+	 * Note: We could be attached to a domain that is not a
+	 * CPU PM domain in that case don't reference the parent.
+	 */
+	cpu_pd = to_cpu_pd(genpd);
+	parent_cpu_pd = to_cpu_pd(parent);
+
+	if (cpu_pd && parent_cpu_pd)
+		cpu_pd->parent = parent_cpu_pd;
+
+skip_parent:
+	of_node_put(dn);
+	return genpd;
+}
+
+/**
+ * of_setup_cpu_pd_single() - Setup the PM domains for a CPU
+ *
+ * @cpu: The CPU for which the PM domain is to be set up.
+ * @ops: The PM domain suspend/resume ops for the CPU's domain
+ *
+ * If the CPU PM domain exists already, then the CPU is attached to
+ * that CPU PD. If it doesn't, the domain is created, the @ops are
+ * set for power_on/power_off callbacks and then the CPU is attached
+ * to that domain. If the domain was created outside this framework,
+ * then we do not attach the CPU to the domain.
+ */
+int of_setup_cpu_pd_single(int cpu, const struct cpu_pd_ops *ops)
+{
+
+	struct device_node *dn;
+	struct generic_pm_domain *genpd;
+
+	dn = of_get_cpu_node(cpu, NULL);
+	if (!dn)
+		return -ENODEV;
+
+	dn = of_parse_phandle(dn, "power-domains", 0);
+	if (!dn)
+		return -ENODEV;
+
+	/* Find the genpd for this CPU, create if not found */
+	genpd = of_get_cpu_domain(dn, ops, cpu);
+	if (IS_ERR(genpd))
+		return PTR_ERR(genpd);
+
+	of_node_put(dn);
+	return cpu_pd_attach_cpu(cpu);
+}
+EXPORT_SYMBOL(of_setup_cpu_pd_single);
+
+/**
+ * of_setup_cpu_pd() - Setup the PM domains for all CPUs
+ *
+ * @ops: The PM domain suspend/resume ops for all the domains
+ *
+ * Setup the CPU PM domain and attach all possible CPUs to their respective
+ * domains. The domains are created if not already and then attached.
+ */
+int of_setup_cpu_pd(const struct cpu_pd_ops *ops)
+{
+	int cpu;
+	int ret;
+
+	for_each_possible_cpu(cpu) {
+		ret = of_setup_cpu_pd_single(cpu, ops);
+		if (ret)
+			break;
+	}
+
+	return ret;
+}
+EXPORT_SYMBOL(of_setup_cpu_pd);
diff --git a/include/linux/cpu_domains.h b/include/linux/cpu_domains.h
new file mode 100644
index 0000000..9530b2d
--- /dev/null
+++ b/include/linux/cpu_domains.h
@@ -0,0 +1,35 @@
+/*
+ * include/linux/cpu_domains.h
+ *
+ * Copyright (C) 2016 Linaro 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.
+ */
+
+#ifndef __CPU_DOMAINS_H__
+#define __CPU_DOMAINS_H__
+
+#include <linux/types.h>
+
+struct cpu_pd_ops {
+	int (*power_off)(u32 state_idx, u32 param);
+	int (*power_on)(void);
+};
+
+#ifdef CONFIG_PM_GENERIC_DOMAINS_OF
+int of_setup_cpu_pd_single(int cpu, const struct cpu_pd_ops *ops);
+int of_setup_cpu_pd(const struct cpu_pd_ops *ops);
+#else
+static inline int of_setup_cpu_pd_single(int cpu, const struct cpu_pd_ops *ops)
+{
+	return -ENODEV;
+}
+static inline int of_setup_cpu_pd(const struct cpu_pd_ops *ops)
+{
+	return -ENODEV;
+}
+#endif /* CONFIG_PM_GENERIC_DOMAINS_OF */
+
+#endif /* __CPU_DOMAINS_H__ */
-- 
2.1.4

[RFC v3 03/12] PM / cpu_domains: Setup PM domains for CPUs/clusters

[Lina Iyer]

Define and add Generic PM domains (genpd) for CPU clusters. Many new
SoCs group CPUs as clusters. Clusters share common resources like power
rails, caches, VFP, Coresight etc. When all CPUs in the cluster are
idle, these shared resources may also be put in their idle state.

CPUs may be associated with their domain providers in DT. The domains in
turn may be associated with their providers. This is clean way to model
the cluster hierarchy like that of ARM's big.little architecture.

For each CPU in the DT, we identify the domain provider; initialize and
register the PM domain if isn't already registered and attach all the
CPU devices to the domain. Usually, when there are multiple clusters of
CPUs, there is a top level coherency domain that is dependent on these
individual domains. All domains thus created are marked IRQ safe
automatically and therefore may be powered down when the CPUs in the
domain are powered down by cpuidle.

Reading DT, initializing Generic PM domains, attaching CPUs to it
domains are common functionalities across ARM SoCs. Provide a common set
of APIs to setup PM domains for CPU clusters and its parents. The
platform drivers may just call of_setup_cpu_pd() to do a single step
setup of CPU domains.

Cc: Ulf Hansson <ulf.hansson@linaro.org>
Cc: Daniel Lezcano <daniel.lezcano@linaro.org>
Cc: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Suggested-by: Kevin Hilman <khilman@linaro.org>
Signed-off-by: Lina Iyer <lina.iyer@linaro.org>
---
 drivers/base/power/Makefile      |   1 +
 drivers/base/power/cpu_domains.c | 267 +++++++++++++++++++++++++++++++++++++++
 include/linux/cpu_domains.h      |  35 +++++
 3 files changed, 303 insertions(+)
 create mode 100644 drivers/base/power/cpu_domains.c
 create mode 100644 include/linux/cpu_domains.h

diff --git a/drivers/base/power/Makefile b/drivers/base/power/Makefile
index 5998c53..9883e89 100644
--- a/drivers/base/power/Makefile
+++ b/drivers/base/power/Makefile
@@ -3,6 +3,7 @@ obj-$(CONFIG_PM_SLEEP)	+= main.o wakeup.o
 obj-$(CONFIG_PM_TRACE_RTC)	+= trace.o
 obj-$(CONFIG_PM_OPP)	+= opp/
 obj-$(CONFIG_PM_GENERIC_DOMAINS)	+=  domain.o domain_governor.o
+obj-$(CONFIG_PM_GENERIC_DOMAINS_OF)	+= cpu_domains.o
 obj-$(CONFIG_HAVE_CLK)	+= clock_ops.o
 
 ccflags-$(CONFIG_DEBUG_DRIVER) := -DDEBUG
diff --git a/drivers/base/power/cpu_domains.c b/drivers/base/power/cpu_domains.c
new file mode 100644
index 0000000..62704e6
--- /dev/null
+++ b/drivers/base/power/cpu_domains.c
@@ -0,0 +1,267 @@
+/*
+ * drivers/base/power/cpu_domains.c - Helper functions to create CPU PM domains.
+ *
+ * Copyright (C) 2016 Linaro 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.
+ */
+
+#include <linux/cpu.h>
+#include <linux/cpu_domains.h>
+#include <linux/cpu_pm.h>
+#include <linux/device.h>
+#include <linux/kernel.h>
+#include <linux/list.h>
+#include <linux/of.h>
+#include <linux/pm_domain.h>
+#include <linux/rculist.h>
+#include <linux/rcupdate.h>
+#include <linux/slab.h>
+
+#define CPU_PD_NAME_MAX 36
+
+struct cpu_pm_domain {
+	struct list_head link;
+	struct cpu_pd_ops ops;
+	struct generic_pm_domain *genpd;
+	struct cpu_pm_domain *parent;
+};
+
+/* List of CPU PM domains we care about */
+static LIST_HEAD(of_cpu_pd_list);
+static DEFINE_MUTEX(cpu_pd_list_lock);
+
+static inline
+struct cpu_pm_domain *to_cpu_pd(struct generic_pm_domain *d)
+{
+	struct cpu_pm_domain *pd;
+	struct cpu_pm_domain *res = NULL;
+
+	rcu_read_lock();
+	list_for_each_entry_rcu(pd, &of_cpu_pd_list, link)
+		if (pd->genpd == d) {
+			res = pd;
+			break;
+		}
+	rcu_read_unlock();
+
+	return res;
+}
+
+static int cpu_pd_attach_cpu(int cpu)
+{
+	int ret;
+	struct device *cpu_dev;
+
+	cpu_dev = get_cpu_device(cpu);
+	if (!cpu_dev) {
+		pr_warn("%s: Unable to get device for CPU%d\n",
+				__func__, cpu);
+		return -ENODEV;
+	}
+
+	ret = genpd_dev_pm_attach(cpu_dev);
+	if (ret)
+		dev_warn(cpu_dev,
+			"%s: Unable to attach to power-domain: %d\n",
+			__func__, ret);
+	else
+		dev_dbg(cpu_dev, "Attached to domain\n");
+
+	return ret;
+}
+
+static int cpu_pd_power_on(struct generic_pm_domain *genpd)
+{
+	struct cpu_pm_domain *pd = to_cpu_pd(genpd);
+
+	return pd->ops.power_on ? pd->ops.power_on() : 0;
+}
+
+static int cpu_pd_power_off(struct generic_pm_domain *genpd)
+{
+	struct cpu_pm_domain *pd = to_cpu_pd(genpd);
+
+	return pd->ops.power_off ? pd->ops.power_off(genpd->state_idx,
+					genpd->states[genpd->state_idx].param),
+					: 0;
+}
+
+/**
+ * of_init_cpu_pm_domain() - Initialize a CPU PM domain from a device node
+ *
+ * @dn: The domain provider's device node
+ * @ops: The power_on/_off callbacks for the domain
+ *
+ * Returns the generic_pm_domain (genpd) pointer to the domain on success
+ */
+static struct generic_pm_domain *of_init_cpu_pm_domain(struct device_node *dn,
+				const struct cpu_pd_ops *ops)
+{
+	struct cpu_pm_domain *pd = NULL;
+	struct generic_pm_domain *genpd = NULL;
+	int ret = -ENOMEM;
+
+	if (!of_device_is_available(dn))
+		return ERR_PTR(-ENODEV);
+
+	genpd = kzalloc(sizeof(*genpd), GFP_KERNEL);
+	if (!genpd)
+		goto fail;
+
+	genpd->name = kstrndup(dn->full_name, CPU_PD_NAME_MAX, GFP_KERNEL);
+	if (!genpd->name)
+		goto fail;
+
+	pd = kzalloc(sizeof(*pd), GFP_KERNEL);
+	if (!pd)
+		goto fail;
+
+	pd->genpd = genpd;
+	pd->genpd->power_off = cpu_pd_power_off;
+	pd->genpd->power_on = cpu_pd_power_on;
+	pd->genpd->flags |= GENPD_FLAG_IRQ_SAFE;
+	pd->ops.power_on = ops->power_on;
+	pd->ops.power_off = ops->power_off;
+
+	INIT_LIST_HEAD_RCU(&pd->link);
+	mutex_lock(&cpu_pd_list_lock);
+	list_add_rcu(&pd->link, &of_cpu_pd_list);
+	mutex_unlock(&cpu_pd_list_lock);
+
+	/* Register the CPU genpd */
+	pr_debug("adding %s as CPU PM domain\n", pd->genpd->name);
+	ret = of_pm_genpd_init(dn, pd->genpd, &simple_qos_governor, false);
+	if (ret) {
+		pr_err("Unable to initialize domain %s\n", dn->full_name);
+		goto fail;
+	}
+
+	ret = of_genpd_add_provider_simple(dn, pd->genpd);
+	if (ret)
+		pr_warn("Unable to add genpd %s as provider\n",
+				pd->genpd->name);
+
+	return pd->genpd;
+fail:
+
+	kfree(genpd->name);
+	kfree(genpd);
+	kfree(pd);
+	return ERR_PTR(ret);
+}
+
+static struct generic_pm_domain *of_get_cpu_domain(struct device_node *dn,
+		const struct cpu_pd_ops *ops, int cpu)
+{
+	struct of_phandle_args args;
+	struct generic_pm_domain *genpd, *parent;
+	struct cpu_pm_domain *cpu_pd, *parent_cpu_pd;
+	int ret;
+
+	/* Do we have this domain? If not, create the domain */
+	args.np = dn;
+	args.args_count = 0;
+
+	genpd = of_genpd_get_from_provider(&args);
+	if (!IS_ERR(genpd))
+		return genpd;
+
+	genpd = of_init_cpu_pm_domain(dn, ops);
+	if (IS_ERR(genpd))
+		return genpd;
+
+	/* Is there a domain provider for this domain? */
+	ret = of_parse_phandle_with_args(dn, "power-domains",
+			"#power-domain-cells", 0, &args);
+	if (ret < 0)
+		goto skip_parent;
+
+	/* Find its parent and attach this domain to it, recursively */
+	parent = of_get_cpu_domain(args.np, ops, cpu);
+	if (IS_ERR(parent))
+		goto skip_parent;
+
+	ret = pm_genpd_add_subdomain(genpd, parent);
+	if (ret) {
+		pr_err("%s: Unable to add sub-domain (%s)\n err: %d",
+				__func__, genpd->name, ret);
+		return ERR_PTR(ret);
+	}
+
+	/*
+	 * Reference parent domain for easy access.
+	 * Note: We could be attached to a domain that is not a
+	 * CPU PM domain in that case don't reference the parent.
+	 */
+	cpu_pd = to_cpu_pd(genpd);
+	parent_cpu_pd = to_cpu_pd(parent);
+
+	if (cpu_pd && parent_cpu_pd)
+		cpu_pd->parent = parent_cpu_pd;
+
+skip_parent:
+	of_node_put(dn);
+	return genpd;
+}
+
+/**
+ * of_setup_cpu_pd_single() - Setup the PM domains for a CPU
+ *
+ * @cpu: The CPU for which the PM domain is to be set up.
+ * @ops: The PM domain suspend/resume ops for the CPU's domain
+ *
+ * If the CPU PM domain exists already, then the CPU is attached to
+ * that CPU PD. If it doesn't, the domain is created, the @ops are
+ * set for power_on/power_off callbacks and then the CPU is attached
+ * to that domain. If the domain was created outside this framework,
+ * then we do not attach the CPU to the domain.
+ */
+int of_setup_cpu_pd_single(int cpu, const struct cpu_pd_ops *ops)
+{
+
+	struct device_node *dn;
+	struct generic_pm_domain *genpd;
+
+	dn = of_get_cpu_node(cpu, NULL);
+	if (!dn)
+		return -ENODEV;
+
+	dn = of_parse_phandle(dn, "power-domains", 0);
+	if (!dn)
+		return -ENODEV;
+
+	/* Find the genpd for this CPU, create if not found */
+	genpd = of_get_cpu_domain(dn, ops, cpu);
+	if (IS_ERR(genpd))
+		return PTR_ERR(genpd);
+
+	of_node_put(dn);
+	return cpu_pd_attach_cpu(cpu);
+}
+EXPORT_SYMBOL(of_setup_cpu_pd_single);
+
+/**
+ * of_setup_cpu_pd() - Setup the PM domains for all CPUs
+ *
+ * @ops: The PM domain suspend/resume ops for all the domains
+ *
+ * Setup the CPU PM domain and attach all possible CPUs to their respective
+ * domains. The domains are created if not already and then attached.
+ */
+int of_setup_cpu_pd(const struct cpu_pd_ops *ops)
+{
+	int cpu;
+	int ret;
+
+	for_each_possible_cpu(cpu) {
+		ret = of_setup_cpu_pd_single(cpu, ops);
+		if (ret)
+			break;
+	}
+
+	return ret;
+}
+EXPORT_SYMBOL(of_setup_cpu_pd);
diff --git a/include/linux/cpu_domains.h b/include/linux/cpu_domains.h
new file mode 100644
index 0000000..9530b2d
--- /dev/null
+++ b/include/linux/cpu_domains.h
@@ -0,0 +1,35 @@
+/*
+ * include/linux/cpu_domains.h
+ *
+ * Copyright (C) 2016 Linaro 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.
+ */
+
+#ifndef __CPU_DOMAINS_H__
+#define __CPU_DOMAINS_H__
+
+#include <linux/types.h>
+
+struct cpu_pd_ops {
+	int (*power_off)(u32 state_idx, u32 param);
+	int (*power_on)(void);
+};
+
+#ifdef CONFIG_PM_GENERIC_DOMAINS_OF
+int of_setup_cpu_pd_single(int cpu, const struct cpu_pd_ops *ops);
+int of_setup_cpu_pd(const struct cpu_pd_ops *ops);
+#else
+static inline int of_setup_cpu_pd_single(int cpu, const struct cpu_pd_ops *ops)
+{
+	return -ENODEV;
+}
+static inline int of_setup_cpu_pd(const struct cpu_pd_ops *ops)
+{
+	return -ENODEV;
+}
+#endif /* CONFIG_PM_GENERIC_DOMAINS_OF */
+
+#endif /* __CPU_DOMAINS_H__ */
-- 
2.1.4

[RFC v3 04/12] ARM: cpuidle: Add runtime PM support for CPUs

[Lina Iyer]

Notify runtime PM when the CPU is going to be powered off in the idle
state. This allows for runtime PM suspend/resume of the CPU as well as
its PM domain.

We do not call into runtime PM for ARM WFI to keep the default state
simple and faster.

Cc: Daniel Lezcano <daniel.lezcano@linaro.org>
Cc: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Signed-off-by: Lina Iyer <lina.iyer@linaro.org>
---
 drivers/cpuidle/cpuidle-arm.c | 55 +++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 55 insertions(+)

diff --git a/drivers/cpuidle/cpuidle-arm.c b/drivers/cpuidle/cpuidle-arm.c
index 545069d..4d6f197 100644
--- a/drivers/cpuidle/cpuidle-arm.c
+++ b/drivers/cpuidle/cpuidle-arm.c
@@ -11,12 +11,14 @@
 
 #define pr_fmt(fmt) "CPUidle arm: " fmt
 
+#include <linux/cpu.h>
 #include <linux/cpuidle.h>
 #include <linux/cpumask.h>
 #include <linux/cpu_pm.h>
 #include <linux/kernel.h>
 #include <linux/module.h>
 #include <linux/of.h>
+#include <linux/pm_runtime.h>
 #include <linux/slab.h>
 
 #include <asm/cpuidle.h>
@@ -37,6 +39,7 @@ static int arm_enter_idle_state(struct cpuidle_device *dev,
 				struct cpuidle_driver *drv, int idx)
 {
 	int ret;
+	struct device *cpu_dev = get_cpu_device(dev->cpu);
 
 	if (!idx) {
 		cpu_do_idle();
@@ -46,12 +49,20 @@ static int arm_enter_idle_state(struct cpuidle_device *dev,
 	ret = cpu_pm_enter();
 	if (!ret) {
 		/*
+		 * Call runtime PM suspend on our device
+		 * Notify RCU to pay attention to critical sections
+		 * called from within runtime PM.
+		 */
+		RCU_NONIDLE(pm_runtime_put_sync_suspend(cpu_dev));
+
+		/*
 		 * Pass idle state index to cpu_suspend which in turn will
 		 * call the CPU ops suspend protocol with idle index as a
 		 * parameter.
 		 */
 		arm_cpuidle_suspend(idx);
 
+		RCU_NONIDLE(pm_runtime_get_sync(cpu_dev));
 		cpu_pm_exit();
 	}
 
@@ -84,6 +95,34 @@ static const struct of_device_id arm_idle_state_match[] __initconst = {
 	{ },
 };
 
+#ifdef CONFIG_HOTPLUG_CPU
+static int arm_idle_cpu_hotplug(struct notifier_block *nb,
+			unsigned long action, void *data)
+{
+	struct device *cpu_dev = get_cpu_device(smp_processor_id());
+
+	/* Execute CPU runtime PM on that CPU */
+	switch (action & ~CPU_TASKS_FROZEN) {
+	case CPU_DYING:
+		pm_runtime_put_sync_suspend(cpu_dev);
+		break;
+	case CPU_STARTING:
+		pm_runtime_get_sync(cpu_dev);
+		break;
+	default:
+		break;
+	}
+
+	return NOTIFY_OK;
+}
+#else
+static int arm_idle_cpu_hotplug(struct notifier_block *nb,
+			unsigned long action, void *data)
+{
+	return NOTIFY_OK;
+}
+#endif
+
 /*
  * arm_idle_init
  *
@@ -96,6 +135,7 @@ static int __init arm_idle_init(void)
 	int cpu, ret;
 	struct cpuidle_driver *drv = &arm_idle_driver;
 	struct cpuidle_device *dev;
+	struct device *cpu_dev;
 
 	/*
 	 * Initialize idle states data, starting at index 1.
@@ -118,6 +158,16 @@ static int __init arm_idle_init(void)
 	 * idle states suspend back-end specific data
 	 */
 	for_each_possible_cpu(cpu) {
+
+		/* Initialize Runtime PM for the CPU */
+		cpu_dev = get_cpu_device(cpu);
+		pm_runtime_irq_safe(cpu_dev);
+		pm_runtime_enable(cpu_dev);
+		if (cpu_online(cpu)) {
+			pm_runtime_get_noresume(cpu_dev);
+			pm_runtime_set_active(cpu_dev);
+		}
+
 		ret = arm_cpuidle_init(cpu);
 
 		/*
@@ -148,10 +198,15 @@ static int __init arm_idle_init(void)
 		}
 	}
 
+	/* Register for hotplug notifications for runtime PM */
+	hotcpu_notifier(arm_idle_cpu_hotplug, 0);
+
 	return 0;
 out_fail:
 	while (--cpu >= 0) {
 		dev = per_cpu(cpuidle_devices, cpu);
+		cpu_dev = get_cpu_device(cpu);
+		__pm_runtime_disable(cpu_dev, false);
 		cpuidle_unregister_device(dev);
 		kfree(dev);
 	}
-- 
2.1.4

[RFC v3 04/12] ARM: cpuidle: Add runtime PM support for CPUs

[Lina Iyer]

Notify runtime PM when the CPU is going to be powered off in the idle
state. This allows for runtime PM suspend/resume of the CPU as well as
its PM domain.

We do not call into runtime PM for ARM WFI to keep the default state
simple and faster.

Cc: Daniel Lezcano <daniel.lezcano@linaro.org>
Cc: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Signed-off-by: Lina Iyer <lina.iyer@linaro.org>
---
 drivers/cpuidle/cpuidle-arm.c | 55 +++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 55 insertions(+)

diff --git a/drivers/cpuidle/cpuidle-arm.c b/drivers/cpuidle/cpuidle-arm.c
index 545069d..4d6f197 100644
--- a/drivers/cpuidle/cpuidle-arm.c
+++ b/drivers/cpuidle/cpuidle-arm.c
@@ -11,12 +11,14 @@
 
 #define pr_fmt(fmt) "CPUidle arm: " fmt
 
+#include <linux/cpu.h>
 #include <linux/cpuidle.h>
 #include <linux/cpumask.h>
 #include <linux/cpu_pm.h>
 #include <linux/kernel.h>
 #include <linux/module.h>
 #include <linux/of.h>
+#include <linux/pm_runtime.h>
 #include <linux/slab.h>
 
 #include <asm/cpuidle.h>
@@ -37,6 +39,7 @@ static int arm_enter_idle_state(struct cpuidle_device *dev,
 				struct cpuidle_driver *drv, int idx)
 {
 	int ret;
+	struct device *cpu_dev = get_cpu_device(dev->cpu);
 
 	if (!idx) {
 		cpu_do_idle();
@@ -46,12 +49,20 @@ static int arm_enter_idle_state(struct cpuidle_device *dev,
 	ret = cpu_pm_enter();
 	if (!ret) {
 		/*
+		 * Call runtime PM suspend on our device
+		 * Notify RCU to pay attention to critical sections
+		 * called from within runtime PM.
+		 */
+		RCU_NONIDLE(pm_runtime_put_sync_suspend(cpu_dev));
+
+		/*
 		 * Pass idle state index to cpu_suspend which in turn will
 		 * call the CPU ops suspend protocol with idle index as a
 		 * parameter.
 		 */
 		arm_cpuidle_suspend(idx);
 
+		RCU_NONIDLE(pm_runtime_get_sync(cpu_dev));
 		cpu_pm_exit();
 	}
 
@@ -84,6 +95,34 @@ static const struct of_device_id arm_idle_state_match[] __initconst = {
 	{ },
 };
 
+#ifdef CONFIG_HOTPLUG_CPU
+static int arm_idle_cpu_hotplug(struct notifier_block *nb,
+			unsigned long action, void *data)
+{
+	struct device *cpu_dev = get_cpu_device(smp_processor_id());
+
+	/* Execute CPU runtime PM on that CPU */
+	switch (action & ~CPU_TASKS_FROZEN) {
+	case CPU_DYING:
+		pm_runtime_put_sync_suspend(cpu_dev);
+		break;
+	case CPU_STARTING:
+		pm_runtime_get_sync(cpu_dev);
+		break;
+	default:
+		break;
+	}
+
+	return NOTIFY_OK;
+}
+#else
+static int arm_idle_cpu_hotplug(struct notifier_block *nb,
+			unsigned long action, void *data)
+{
+	return NOTIFY_OK;
+}
+#endif
+
 /*
  * arm_idle_init
  *
@@ -96,6 +135,7 @@ static int __init arm_idle_init(void)
 	int cpu, ret;
 	struct cpuidle_driver *drv = &arm_idle_driver;
 	struct cpuidle_device *dev;
+	struct device *cpu_dev;
 
 	/*
 	 * Initialize idle states data, starting at index 1.
@@ -118,6 +158,16 @@ static int __init arm_idle_init(void)
 	 * idle states suspend back-end specific data
 	 */
 	for_each_possible_cpu(cpu) {
+
+		/* Initialize Runtime PM for the CPU */
+		cpu_dev = get_cpu_device(cpu);
+		pm_runtime_irq_safe(cpu_dev);
+		pm_runtime_enable(cpu_dev);
+		if (cpu_online(cpu)) {
+			pm_runtime_get_noresume(cpu_dev);
+			pm_runtime_set_active(cpu_dev);
+		}
+
 		ret = arm_cpuidle_init(cpu);
 
 		/*
@@ -148,10 +198,15 @@ static int __init arm_idle_init(void)
 		}
 	}
 
+	/* Register for hotplug notifications for runtime PM */
+	hotcpu_notifier(arm_idle_cpu_hotplug, 0);
+
 	return 0;
 out_fail:
 	while (--cpu >= 0) {
 		dev = per_cpu(cpuidle_devices, cpu);
+		cpu_dev = get_cpu_device(cpu);
+		__pm_runtime_disable(cpu_dev, false);
 		cpuidle_unregister_device(dev);
 		kfree(dev);
 	}
-- 
2.1.4

[RFC v3 05/12] timer: Export next wake up of a CPU

[Lina Iyer]

Knowing the sleep length of the CPU is useful for the power state
determination on idle. However, when the common sleep time between
multiple CPUs is needed, the sleep length of a CPU is not useful.

By reading the next wake up event of a CPU, governors can determine the
first CPU to wake up (due to timer) amongst a cluster of CPUs and the
sleep time available between the last CPU to idle and the first CPU to
resume. This information is useful to determine if the caches and other
common hardware blocks can also be put in idle during this common period
of inactivity.

Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Lina Iyer <lina.iyer@linaro.org>
---
 include/linux/tick.h     | 10 ++++++++++
 kernel/time/tick-sched.c | 13 +++++++++++++
 2 files changed, 23 insertions(+)

diff --git a/include/linux/tick.h b/include/linux/tick.h
index 97fd4e5..b8a2e06 100644
--- a/include/linux/tick.h
+++ b/include/linux/tick.h
@@ -104,6 +104,7 @@ extern void tick_nohz_idle_enter(void);
 extern void tick_nohz_idle_exit(void);
 extern void tick_nohz_irq_exit(void);
 extern ktime_t tick_nohz_get_sleep_length(void);
+extern ktime_t tick_nohz_get_next_wakeup(int cpu);
 extern u64 get_cpu_idle_time_us(int cpu, u64 *last_update_time);
 extern u64 get_cpu_iowait_time_us(int cpu, u64 *last_update_time);
 #else /* !CONFIG_NO_HZ_COMMON */
@@ -118,6 +119,15 @@ static inline ktime_t tick_nohz_get_sleep_length(void)
 
 	return len;
 }
+
+static inline ktime_t tick_nohz_get_next_wakeup(int cpu)
+{
+	ktime_t len = { .tv64 = NSEC_PER_SEC/HZ };
+
+	/* Next wake up is the tick period, assume it starts now */
+	return ktime_add(len, ktime_get());
+}
+
 static inline u64 get_cpu_idle_time_us(int cpu, u64 *unused) { return -1; }
 static inline u64 get_cpu_iowait_time_us(int cpu, u64 *unused) { return -1; }
 #endif /* !CONFIG_NO_HZ_COMMON */
diff --git a/kernel/time/tick-sched.c b/kernel/time/tick-sched.c
index 0b17424..f0ddaec 100644
--- a/kernel/time/tick-sched.c
+++ b/kernel/time/tick-sched.c
@@ -888,6 +888,19 @@ ktime_t tick_nohz_get_sleep_length(void)
 	return ts->sleep_length;
 }
 
+/**
+ * tick_nohz_get_next_wakeup - return the next wake up of the CPU
+ *
+ * Called with interrupts disabled on the cpu
+ */
+ktime_t tick_nohz_get_next_wakeup(int cpu)
+{
+	struct clock_event_device *dev =
+			per_cpu(tick_cpu_device.evtdev, cpu);
+
+	return dev->next_event;
+}
+
 static void tick_nohz_account_idle_ticks(struct tick_sched *ts)
 {
 #ifndef CONFIG_VIRT_CPU_ACCOUNTING_NATIVE
-- 
2.1.4

[RFC v3 05/12] timer: Export next wake up of a CPU

[Lina Iyer]

Knowing the sleep length of the CPU is useful for the power state
determination on idle. However, when the common sleep time between
multiple CPUs is needed, the sleep length of a CPU is not useful.

By reading the next wake up event of a CPU, governors can determine the
first CPU to wake up (due to timer) amongst a cluster of CPUs and the
sleep time available between the last CPU to idle and the first CPU to
resume. This information is useful to determine if the caches and other
common hardware blocks can also be put in idle during this common period
of inactivity.

Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Lina Iyer <lina.iyer@linaro.org>
---
 include/linux/tick.h     | 10 ++++++++++
 kernel/time/tick-sched.c | 13 +++++++++++++
 2 files changed, 23 insertions(+)

diff --git a/include/linux/tick.h b/include/linux/tick.h
index 97fd4e5..b8a2e06 100644
--- a/include/linux/tick.h
+++ b/include/linux/tick.h
@@ -104,6 +104,7 @@ extern void tick_nohz_idle_enter(void);
 extern void tick_nohz_idle_exit(void);
 extern void tick_nohz_irq_exit(void);
 extern ktime_t tick_nohz_get_sleep_length(void);
+extern ktime_t tick_nohz_get_next_wakeup(int cpu);
 extern u64 get_cpu_idle_time_us(int cpu, u64 *last_update_time);
 extern u64 get_cpu_iowait_time_us(int cpu, u64 *last_update_time);
 #else /* !CONFIG_NO_HZ_COMMON */
@@ -118,6 +119,15 @@ static inline ktime_t tick_nohz_get_sleep_length(void)
 
 	return len;
 }
+
+static inline ktime_t tick_nohz_get_next_wakeup(int cpu)
+{
+	ktime_t len = { .tv64 = NSEC_PER_SEC/HZ };
+
+	/* Next wake up is the tick period, assume it starts now */
+	return ktime_add(len, ktime_get());
+}
+
 static inline u64 get_cpu_idle_time_us(int cpu, u64 *unused) { return -1; }
 static inline u64 get_cpu_iowait_time_us(int cpu, u64 *unused) { return -1; }
 #endif /* !CONFIG_NO_HZ_COMMON */
diff --git a/kernel/time/tick-sched.c b/kernel/time/tick-sched.c
index 0b17424..f0ddaec 100644
--- a/kernel/time/tick-sched.c
+++ b/kernel/time/tick-sched.c
@@ -888,6 +888,19 @@ ktime_t tick_nohz_get_sleep_length(void)
 	return ts->sleep_length;
 }
 
+/**
+ * tick_nohz_get_next_wakeup - return the next wake up of the CPU
+ *
+ * Called with interrupts disabled on the cpu
+ */
+ktime_t tick_nohz_get_next_wakeup(int cpu)
+{
+	struct clock_event_device *dev =
+			per_cpu(tick_cpu_device.evtdev, cpu);
+
+	return dev->next_event;
+}
+
 static void tick_nohz_account_idle_ticks(struct tick_sched *ts)
 {
 #ifndef CONFIG_VIRT_CPU_ACCOUNTING_NATIVE
-- 
2.1.4

[RFC v3 06/12] PM / cpu_domains: Record CPUs that are part of the domain

[Lina Iyer]

In order to power down a CPU domain, the domain needs information about
the CPUs in that domain. The reference counting for the CPU devices in a
domain is done by genpd. In order to understand the idle time for the
domain, it is necessary to know which CPUs are part of the domain, so
the domain governor may understand the sleep durations of the comprising
CPU devices and make a judicious decision on the domain's idle state.
This extends to the parent of such domains, which may have multiple such
CPU domains and therefore would need to know the sleep patterns of all
the CPUs in all the CPU domains.

To aid this functionality, traverse up the parent chain and set the CPU
in the cpumasks while attaching a CPU to its domain. This mask is
provided in the callback to the platform driver to help identify the
CPUs in the domain that is being powered off.

Signed-off-by: Lina Iyer <lina.iyer@linaro.org>
---
 drivers/base/power/cpu_domains.c | 28 ++++++++++++++++++++++++----
 include/linux/cpu_domains.h      |  4 +++-
 2 files changed, 27 insertions(+), 5 deletions(-)

diff --git a/drivers/base/power/cpu_domains.c b/drivers/base/power/cpu_domains.c
index 62704e6..62c1ab9 100644
--- a/drivers/base/power/cpu_domains.c
+++ b/drivers/base/power/cpu_domains.c
@@ -9,6 +9,7 @@
  */
 
 #include <linux/cpu.h>
+#include <linux/cpumask.h>
 #include <linux/cpu_domains.h>
 #include <linux/cpu_pm.h>
 #include <linux/device.h>
@@ -27,6 +28,7 @@ struct cpu_pm_domain {
 	struct cpu_pd_ops ops;
 	struct generic_pm_domain *genpd;
 	struct cpu_pm_domain *parent;
+	cpumask_var_t cpus;
 };
 
 /* List of CPU PM domains we care about */
@@ -50,7 +52,7 @@ struct cpu_pm_domain *to_cpu_pd(struct generic_pm_domain *d)
 	return res;
 }
 
-static int cpu_pd_attach_cpu(int cpu)
+static int cpu_pd_attach_cpu(struct cpu_pm_domain *cpu_pd, int cpu)
 {
 	int ret;
 	struct device *cpu_dev;
@@ -70,6 +72,11 @@ static int cpu_pd_attach_cpu(int cpu)
 	else
 		dev_dbg(cpu_dev, "Attached to domain\n");
 
+	while (!ret && cpu_pd) {
+		cpumask_set_cpu(cpu, cpu_pd->cpus);
+		cpu_pd = cpu_pd->parent;
+	};
+
 	return ret;
 }
 
@@ -85,8 +92,8 @@ static int cpu_pd_power_off(struct generic_pm_domain *genpd)
 	struct cpu_pm_domain *pd = to_cpu_pd(genpd);
 
 	return pd->ops.power_off ? pd->ops.power_off(genpd->state_idx,
-					genpd->states[genpd->state_idx].param),
-					: 0;
+					genpd->states[genpd->state_idx].param,
+					pd->cpus) : 0;
 }
 
 /**
@@ -119,6 +126,9 @@ static struct generic_pm_domain *of_init_cpu_pm_domain(struct device_node *dn,
 	if (!pd)
 		goto fail;
 
+	if (!zalloc_cpumask_var(&pd->cpus, GFP_KERNEL))
+		goto fail;
+
 	pd->genpd = genpd;
 	pd->genpd->power_off = cpu_pd_power_off;
 	pd->genpd->power_on = cpu_pd_power_on;
@@ -149,6 +159,8 @@ fail:
 
 	kfree(genpd->name);
 	kfree(genpd);
+	if (pd)
+		kfree(pd->cpus);
 	kfree(pd);
 	return ERR_PTR(ret);
 }
@@ -224,6 +236,7 @@ int of_setup_cpu_pd_single(int cpu, const struct cpu_pd_ops *ops)
 
 	struct device_node *dn;
 	struct generic_pm_domain *genpd;
+	struct cpu_pm_domain *cpu_pd;
 
 	dn = of_get_cpu_node(cpu, NULL);
 	if (!dn)
@@ -239,7 +252,14 @@ int of_setup_cpu_pd_single(int cpu, const struct cpu_pd_ops *ops)
 		return PTR_ERR(genpd);
 
 	of_node_put(dn);
-	return cpu_pd_attach_cpu(cpu);
+	cpu_pd = to_cpu_pd(genpd);
+	if (!cpu_pd) {
+		pr_err("%s: Genpd was created outside CPU PM domains\n",
+				__func__);
+		return -ENOENT;
+	}
+
+	return cpu_pd_attach_cpu(cpu_pd, cpu);
 }
 EXPORT_SYMBOL(of_setup_cpu_pd_single);
 
diff --git a/include/linux/cpu_domains.h b/include/linux/cpu_domains.h
index 9530b2d..50e3321 100644
--- a/include/linux/cpu_domains.h
+++ b/include/linux/cpu_domains.h
@@ -13,8 +13,10 @@
 
 #include <linux/types.h>
 
+struct cpumask;
+
 struct cpu_pd_ops {
-	int (*power_off)(u32 state_idx, u32 param);
+	int (*power_off)(u32 state_idx, u32 param, const struct cpumask *mask);
 	int (*power_on)(void);
 };
 
-- 
2.1.4

[RFC v3 06/12] PM / cpu_domains: Record CPUs that are part of the domain

[Lina Iyer]

In order to power down a CPU domain, the domain needs information about
the CPUs in that domain. The reference counting for the CPU devices in a
domain is done by genpd. In order to understand the idle time for the
domain, it is necessary to know which CPUs are part of the domain, so
the domain governor may understand the sleep durations of the comprising
CPU devices and make a judicious decision on the domain's idle state.
This extends to the parent of such domains, which may have multiple such
CPU domains and therefore would need to know the sleep patterns of all
the CPUs in all the CPU domains.

To aid this functionality, traverse up the parent chain and set the CPU
in the cpumasks while attaching a CPU to its domain. This mask is
provided in the callback to the platform driver to help identify the
CPUs in the domain that is being powered off.

Signed-off-by: Lina Iyer <lina.iyer@linaro.org>
---
 drivers/base/power/cpu_domains.c | 28 ++++++++++++++++++++++++----
 include/linux/cpu_domains.h      |  4 +++-
 2 files changed, 27 insertions(+), 5 deletions(-)

diff --git a/drivers/base/power/cpu_domains.c b/drivers/base/power/cpu_domains.c
index 62704e6..62c1ab9 100644
--- a/drivers/base/power/cpu_domains.c
+++ b/drivers/base/power/cpu_domains.c
@@ -9,6 +9,7 @@
  */
 
 #include <linux/cpu.h>
+#include <linux/cpumask.h>
 #include <linux/cpu_domains.h>
 #include <linux/cpu_pm.h>
 #include <linux/device.h>
@@ -27,6 +28,7 @@ struct cpu_pm_domain {
 	struct cpu_pd_ops ops;
 	struct generic_pm_domain *genpd;
 	struct cpu_pm_domain *parent;
+	cpumask_var_t cpus;
 };
 
 /* List of CPU PM domains we care about */
@@ -50,7 +52,7 @@ struct cpu_pm_domain *to_cpu_pd(struct generic_pm_domain *d)
 	return res;
 }
 
-static int cpu_pd_attach_cpu(int cpu)
+static int cpu_pd_attach_cpu(struct cpu_pm_domain *cpu_pd, int cpu)
 {
 	int ret;
 	struct device *cpu_dev;
@@ -70,6 +72,11 @@ static int cpu_pd_attach_cpu(int cpu)
 	else
 		dev_dbg(cpu_dev, "Attached to domain\n");
 
+	while (!ret && cpu_pd) {
+		cpumask_set_cpu(cpu, cpu_pd->cpus);
+		cpu_pd = cpu_pd->parent;
+	};
+
 	return ret;
 }
 
@@ -85,8 +92,8 @@ static int cpu_pd_power_off(struct generic_pm_domain *genpd)
 	struct cpu_pm_domain *pd = to_cpu_pd(genpd);
 
 	return pd->ops.power_off ? pd->ops.power_off(genpd->state_idx,
-					genpd->states[genpd->state_idx].param),
-					: 0;
+					genpd->states[genpd->state_idx].param,
+					pd->cpus) : 0;
 }
 
 /**
@@ -119,6 +126,9 @@ static struct generic_pm_domain *of_init_cpu_pm_domain(struct device_node *dn,
 	if (!pd)
 		goto fail;
 
+	if (!zalloc_cpumask_var(&pd->cpus, GFP_KERNEL))
+		goto fail;
+
 	pd->genpd = genpd;
 	pd->genpd->power_off = cpu_pd_power_off;
 	pd->genpd->power_on = cpu_pd_power_on;
@@ -149,6 +159,8 @@ fail:
 
 	kfree(genpd->name);
 	kfree(genpd);
+	if (pd)
+		kfree(pd->cpus);
 	kfree(pd);
 	return ERR_PTR(ret);
 }
@@ -224,6 +236,7 @@ int of_setup_cpu_pd_single(int cpu, const struct cpu_pd_ops *ops)
 
 	struct device_node *dn;
 	struct generic_pm_domain *genpd;
+	struct cpu_pm_domain *cpu_pd;
 
 	dn = of_get_cpu_node(cpu, NULL);
 	if (!dn)
@@ -239,7 +252,14 @@ int of_setup_cpu_pd_single(int cpu, const struct cpu_pd_ops *ops)
 		return PTR_ERR(genpd);
 
 	of_node_put(dn);
-	return cpu_pd_attach_cpu(cpu);
+	cpu_pd = to_cpu_pd(genpd);
+	if (!cpu_pd) {
+		pr_err("%s: Genpd was created outside CPU PM domains\n",
+				__func__);
+		return -ENOENT;
+	}
+
+	return cpu_pd_attach_cpu(cpu_pd, cpu);
 }
 EXPORT_SYMBOL(of_setup_cpu_pd_single);
 
diff --git a/include/linux/cpu_domains.h b/include/linux/cpu_domains.h
index 9530b2d..50e3321 100644
--- a/include/linux/cpu_domains.h
+++ b/include/linux/cpu_domains.h
@@ -13,8 +13,10 @@
 
 #include <linux/types.h>
 
+struct cpumask;
+
 struct cpu_pd_ops {
-	int (*power_off)(u32 state_idx, u32 param);
+	int (*power_off)(u32 state_idx, u32 param, const struct cpumask *mask);
 	int (*power_on)(void);
 };
 
-- 
2.1.4

[RFC v3 07/12] PM / cpu_domains: Add PM Domain governor for CPUs

[Lina Iyer]

A PM domain comprising of CPUs may be powered off when all the CPUs in
the domain are powered down. Powering down a CPU domain is generally a
expensive operation and therefore the power performance trade offs
should be considered. The time between the last CPU powering down and
the first CPU powering up in a domain, is the time available for the
domain to sleep. Ideally, the sleep time of the domain should fulfill
the residency requirement of the domains' idle state.

To do this effectively, read the time before the wakeup of the cluster's
CPUs and ensure that the domain's idle state sleep time guarantees the
QoS requirements of each of the CPU, the PM QoS CPU_DMA_LATENCY and the
state's residency.

Signed-off-by: Lina Iyer <lina.iyer@linaro.org>
---
 drivers/base/power/cpu_domains.c | 80 +++++++++++++++++++++++++++++++++++++++-
 1 file changed, 79 insertions(+), 1 deletion(-)

diff --git a/drivers/base/power/cpu_domains.c b/drivers/base/power/cpu_domains.c
index 62c1ab9..6ba05f8 100644
--- a/drivers/base/power/cpu_domains.c
+++ b/drivers/base/power/cpu_domains.c
@@ -17,9 +17,12 @@
 #include <linux/list.h>
 #include <linux/of.h>
 #include <linux/pm_domain.h>
+#include <linux/pm_qos.h>
+#include <linux/pm_runtime.h>
 #include <linux/rculist.h>
 #include <linux/rcupdate.h>
 #include <linux/slab.h>
+#include <linux/tick.h>
 
 #define CPU_PD_NAME_MAX 36
 
@@ -52,6 +55,81 @@ struct cpu_pm_domain *to_cpu_pd(struct generic_pm_domain *d)
 	return res;
 }
 
+static bool cpu_pd_down_ok(struct dev_pm_domain *pd)
+{
+	struct generic_pm_domain *genpd = pd_to_genpd(pd);
+	struct cpu_pm_domain *cpu_pd = to_cpu_pd(genpd);
+	int qos_ns = pm_qos_request(PM_QOS_CPU_DMA_LATENCY);
+	u64 sleep_ns;
+	ktime_t earliest, next_wakeup;
+	int cpu;
+	int i;
+
+	/* Reset the last set genpd state, default to index 0 */
+	genpd->state_idx = 0;
+
+	/* We don't want to power down, if QoS is 0 */
+	if (!qos_ns)
+		return false;
+
+	/*
+	 * Find the sleep time for the cluster.
+	 * The time between now and the first wake up of any CPU that
+	 * are in this domain hierarchy is the time available for the
+	 * domain to be idle.
+	 *
+	 * We only care about the next wakeup for any online CPU in that
+	 * cluster. Hotplug off any of the CPUs that we care about will
+	 * wait on the genpd lock, until we are done. Any other CPU hotplug
+	 * is not of consequence to our sleep time.
+	 */
+	earliest = ktime_set(KTIME_SEC_MAX, 0);
+	for_each_cpu_and(cpu, cpu_pd->cpus, cpu_online_mask) {
+		next_wakeup = tick_nohz_get_next_wakeup(cpu);
+		if (earliest.tv64 > next_wakeup.tv64)
+			earliest = next_wakeup;
+	}
+
+	sleep_ns = ktime_to_ns(ktime_sub(earliest, ktime_get()));
+	if (sleep_ns <= 0)
+		return false;
+
+	/*
+	 * Find the deepest sleep state that satisfies the residency
+	 * requirement and the QoS constraint
+	 */
+	for (i = genpd->state_count - 1; i >= 0; i--) {
+		u64 state_sleep_ns;
+
+		state_sleep_ns = genpd->states[i].power_off_latency_ns +
+			genpd->states[i].power_on_latency_ns +
+			genpd->states[i].residency_ns;
+
+		/*
+		 * If we can't sleep to save power in the state, move on
+		 * to the next lower idle state.
+		 */
+		if (state_sleep_ns > sleep_ns)
+			continue;
+
+		/*
+		 * We also don't want to sleep more than we should to
+		 * gaurantee QoS.
+		 */
+		if (state_sleep_ns < (qos_ns * NSEC_PER_USEC))
+			break;
+	}
+
+	if (i >= 0)
+		genpd->state_idx = i;
+
+	return (i >= 0);
+}
+
+static struct dev_power_governor cpu_pd_gov = {
+	.power_down_ok = cpu_pd_down_ok,
+};
+
 static int cpu_pd_attach_cpu(struct cpu_pm_domain *cpu_pd, int cpu)
 {
 	int ret;
@@ -143,7 +221,7 @@ static struct generic_pm_domain *of_init_cpu_pm_domain(struct device_node *dn,
 
 	/* Register the CPU genpd */
 	pr_debug("adding %s as CPU PM domain\n", pd->genpd->name);
-	ret = of_pm_genpd_init(dn, pd->genpd, &simple_qos_governor, false);
+	ret = of_pm_genpd_init(dn, pd->genpd, &cpu_pd_gov, false);
 	if (ret) {
 		pr_err("Unable to initialize domain %s\n", dn->full_name);
 		goto fail;
-- 
2.1.4

[RFC v3 07/12] PM / cpu_domains: Add PM Domain governor for CPUs

[Lina Iyer]

A PM domain comprising of CPUs may be powered off when all the CPUs in
the domain are powered down. Powering down a CPU domain is generally a
expensive operation and therefore the power performance trade offs
should be considered. The time between the last CPU powering down and
the first CPU powering up in a domain, is the time available for the
domain to sleep. Ideally, the sleep time of the domain should fulfill
the residency requirement of the domains' idle state.

To do this effectively, read the time before the wakeup of the cluster's
CPUs and ensure that the domain's idle state sleep time guarantees the
QoS requirements of each of the CPU, the PM QoS CPU_DMA_LATENCY and the
state's residency.

Signed-off-by: Lina Iyer <lina.iyer@linaro.org>
---
 drivers/base/power/cpu_domains.c | 80 +++++++++++++++++++++++++++++++++++++++-
 1 file changed, 79 insertions(+), 1 deletion(-)

diff --git a/drivers/base/power/cpu_domains.c b/drivers/base/power/cpu_domains.c
index 62c1ab9..6ba05f8 100644
--- a/drivers/base/power/cpu_domains.c
+++ b/drivers/base/power/cpu_domains.c
@@ -17,9 +17,12 @@
 #include <linux/list.h>
 #include <linux/of.h>
 #include <linux/pm_domain.h>
+#include <linux/pm_qos.h>
+#include <linux/pm_runtime.h>
 #include <linux/rculist.h>
 #include <linux/rcupdate.h>
 #include <linux/slab.h>
+#include <linux/tick.h>
 
 #define CPU_PD_NAME_MAX 36
 
@@ -52,6 +55,81 @@ struct cpu_pm_domain *to_cpu_pd(struct generic_pm_domain *d)
 	return res;
 }
 
+static bool cpu_pd_down_ok(struct dev_pm_domain *pd)
+{
+	struct generic_pm_domain *genpd = pd_to_genpd(pd);
+	struct cpu_pm_domain *cpu_pd = to_cpu_pd(genpd);
+	int qos_ns = pm_qos_request(PM_QOS_CPU_DMA_LATENCY);
+	u64 sleep_ns;
+	ktime_t earliest, next_wakeup;
+	int cpu;
+	int i;
+
+	/* Reset the last set genpd state, default to index 0 */
+	genpd->state_idx = 0;
+
+	/* We don't want to power down, if QoS is 0 */
+	if (!qos_ns)
+		return false;
+
+	/*
+	 * Find the sleep time for the cluster.
+	 * The time between now and the first wake up of any CPU that
+	 * are in this domain hierarchy is the time available for the
+	 * domain to be idle.
+	 *
+	 * We only care about the next wakeup for any online CPU in that
+	 * cluster. Hotplug off any of the CPUs that we care about will
+	 * wait on the genpd lock, until we are done. Any other CPU hotplug
+	 * is not of consequence to our sleep time.
+	 */
+	earliest = ktime_set(KTIME_SEC_MAX, 0);
+	for_each_cpu_and(cpu, cpu_pd->cpus, cpu_online_mask) {
+		next_wakeup = tick_nohz_get_next_wakeup(cpu);
+		if (earliest.tv64 > next_wakeup.tv64)
+			earliest = next_wakeup;
+	}
+
+	sleep_ns = ktime_to_ns(ktime_sub(earliest, ktime_get()));
+	if (sleep_ns <= 0)
+		return false;
+
+	/*
+	 * Find the deepest sleep state that satisfies the residency
+	 * requirement and the QoS constraint
+	 */
+	for (i = genpd->state_count - 1; i >= 0; i--) {
+		u64 state_sleep_ns;
+
+		state_sleep_ns = genpd->states[i].power_off_latency_ns +
+			genpd->states[i].power_on_latency_ns +
+			genpd->states[i].residency_ns;
+
+		/*
+		 * If we can't sleep to save power in the state, move on
+		 * to the next lower idle state.
+		 */
+		if (state_sleep_ns > sleep_ns)
+			continue;
+
+		/*
+		 * We also don't want to sleep more than we should to
+		 * gaurantee QoS.
+		 */
+		if (state_sleep_ns < (qos_ns * NSEC_PER_USEC))
+			break;
+	}
+
+	if (i >= 0)
+		genpd->state_idx = i;
+
+	return (i >= 0);
+}
+
+static struct dev_power_governor cpu_pd_gov = {
+	.power_down_ok = cpu_pd_down_ok,
+};
+
 static int cpu_pd_attach_cpu(struct cpu_pm_domain *cpu_pd, int cpu)
 {
 	int ret;
@@ -143,7 +221,7 @@ static struct generic_pm_domain *of_init_cpu_pm_domain(struct device_node *dn,
 
 	/* Register the CPU genpd */
 	pr_debug("adding %s as CPU PM domain\n", pd->genpd->name);
-	ret = of_pm_genpd_init(dn, pd->genpd, &simple_qos_governor, false);
+	ret = of_pm_genpd_init(dn, pd->genpd, &cpu_pd_gov, false);
 	if (ret) {
 		pr_err("Unable to initialize domain %s\n", dn->full_name);
 		goto fail;
-- 
2.1.4

[RFC v3 08/12] Documentation / cpu_domains: Describe CPU PM domains setup and governor

[Lina Iyer]

A generic CPU PM domain functionality is provided by
drivers/base/power/cpu_domains.c. This document describes the generic
usecase of CPU's PM domains, the setup of such domains and a CPU
specific genpd governor.

Signed-off-by: Lina Iyer <lina.iyer@linaro.org>
---
 Documentation/power/cpu_domains.txt | 79 +++++++++++++++++++++++++++++++++++++
 1 file changed, 79 insertions(+)
 create mode 100644 Documentation/power/cpu_domains.txt

diff --git a/Documentation/power/cpu_domains.txt b/Documentation/power/cpu_domains.txt
new file mode 100644
index 0000000..bd99e92
--- /dev/null
+++ b/Documentation/power/cpu_domains.txt
@@ -0,0 +1,79 @@
+CPU PM domains
+==============
+
+Newer CPUs are grouped in SoCs as clusters. A cluster in addition to the CPUs
+may have caches, floating point units and other architecture specific power
+controller that share resources when any of the CPUs are active. When the CPUs
+are in idle, some of these cluster components may also idle. A cluster may
+also be nested inside another cluster that provides common coherency
+interfaces to share data between the clusters. The organization of such
+clusters and CPU may be descibed in DT, since they are SoC specific.
+
+CPUIdle framework enables the CPUs to determine the sleep time and enter low
+power state to save power during periods of idle. CPUs in a cluster may enter
+and exit idle state independently of each other. During the time when all the
+CPUs are in idle state, the cluster may safely put some of the shared
+resources in their idle state. The time between the last CPU to enter idle and
+the first CPU to wake up is the time available for the cluster to enter its
+idle state.
+
+When SoCs power down the CPU during cpuidle, they generally have supplemental
+hardware that can handshake with the CPU with a signal that indicates that the
+CPU has stopped execution. The hardware is also responsible for warm booting
+the CPU on receiving an interrupt. In a cluster architecture, common resources
+that are shared by a cluster may also be powered down by an external
+microcontroller or a processor. The microcontroller may be programmed in
+advance to put the hardware blocks in a low power state, when the last active
+CPU sends the idle signal. When the signal is received, the microcontroller
+may trigger the hardware blocks to enter their low power state. When an
+interrupt to wakeup the processor is received, the microcontroller is
+responsible for bringing up the hardware blocks to its active state, before
+waking up the CPU. The timelines for such operations should be in the
+acceptable range for for CPU idle to get power benefits.
+
+CPU PM Domain Setup
+-------------------
+
+PM domains are represented in the DT as domain consumers and providers. A
+device may have a domain provider and a domain provider may support multiple
+domain consumers. Domains like clusters, may also be nested inside one
+another. A domain that has no active consumer, may be powered off and any
+resuming consumer would trigger the domain back to active. Parent domains may
+be powered off when the child domains are powered off. The CPU cluster can be
+fashioned as a PM domain. When the CPU devices are powered off, the PM domain
+may be powered off.
+
+Device idle is reference counted by runtime PM. When there is no active need
+for the device, runtime PM invokes callbacks to suspend the parent domain.
+Generic PM domain (genpd) handles the hierarchy of devices, domains and the
+reference counting of objects leading to last man down and first man up in the
+domain. The CPU domains helper functions defines PM domains for each CPU
+cluster and attaches the CPU devices to the respective PM domains.
+
+Platform drivers may use the following API to register their CPU PM domains.
+
+of_setup_cpu_pd() -
+Provides a single step registration of the CPU PM domain and attach CPUs to
+the genpd. Platform drivers may additionally register callbacks for power_on
+and power_off operations for the PM domain.
+
+of_setup_cpu_pd_single() -
+Define PM domain for a single CPU and attach the CPU to its domain.
+
+
+CPU PM Domain governor
+----------------------
+
+CPUs have a unique ability to determine their next wakeup. CPUs may wake up
+for known timer interrupts and unknown interrupts from idle. Prediction
+algorithms and heuristic based algorithms like the Menu governor for cpuidle
+can determine the next wakeup of the CPU. However, determining the wakeup
+across a group of CPUs is a tough problem to solve.
+
+A simplistic approach would be to resort to known wakeups of the CPUs in
+determining the next wakeup of any CPU in the cluster. The CPU PM domain
+governor does just that. By looking into the tick device of the CPUs, the
+governor can determine the sleep time between the last CPU and the first
+scheduled wakeup of any CPU in that domain. This combined with the PM QoS
+requirement for CPU_DMA_LATENCY can be used to determine the deepest possible
+idle state of the CPU domain.
-- 
2.1.4

[RFC v3 08/12] Documentation / cpu_domains: Describe CPU PM domains setup and governor

[Lina Iyer]

A generic CPU PM domain functionality is provided by
drivers/base/power/cpu_domains.c. This document describes the generic
usecase of CPU's PM domains, the setup of such domains and a CPU
specific genpd governor.

Signed-off-by: Lina Iyer <lina.iyer@linaro.org>
---
 Documentation/power/cpu_domains.txt | 79 +++++++++++++++++++++++++++++++++++++
 1 file changed, 79 insertions(+)
 create mode 100644 Documentation/power/cpu_domains.txt

diff --git a/Documentation/power/cpu_domains.txt b/Documentation/power/cpu_domains.txt
new file mode 100644
index 0000000..bd99e92
--- /dev/null
+++ b/Documentation/power/cpu_domains.txt
@@ -0,0 +1,79 @@
+CPU PM domains
+==============
+
+Newer CPUs are grouped in SoCs as clusters. A cluster in addition to the CPUs
+may have caches, floating point units and other architecture specific power
+controller that share resources when any of the CPUs are active. When the CPUs
+are in idle, some of these cluster components may also idle. A cluster may
+also be nested inside another cluster that provides common coherency
+interfaces to share data between the clusters. The organization of such
+clusters and CPU may be descibed in DT, since they are SoC specific.
+
+CPUIdle framework enables the CPUs to determine the sleep time and enter low
+power state to save power during periods of idle. CPUs in a cluster may enter
+and exit idle state independently of each other. During the time when all the
+CPUs are in idle state, the cluster may safely put some of the shared
+resources in their idle state. The time between the last CPU to enter idle and
+the first CPU to wake up is the time available for the cluster to enter its
+idle state.
+
+When SoCs power down the CPU during cpuidle, they generally have supplemental
+hardware that can handshake with the CPU with a signal that indicates that the
+CPU has stopped execution. The hardware is also responsible for warm booting
+the CPU on receiving an interrupt. In a cluster architecture, common resources
+that are shared by a cluster may also be powered down by an external
+microcontroller or a processor. The microcontroller may be programmed in
+advance to put the hardware blocks in a low power state, when the last active
+CPU sends the idle signal. When the signal is received, the microcontroller
+may trigger the hardware blocks to enter their low power state. When an
+interrupt to wakeup the processor is received, the microcontroller is
+responsible for bringing up the hardware blocks to its active state, before
+waking up the CPU. The timelines for such operations should be in the
+acceptable range for for CPU idle to get power benefits.
+
+CPU PM Domain Setup
+-------------------
+
+PM domains are represented in the DT as domain consumers and providers. A
+device may have a domain provider and a domain provider may support multiple
+domain consumers. Domains like clusters, may also be nested inside one
+another. A domain that has no active consumer, may be powered off and any
+resuming consumer would trigger the domain back to active. Parent domains may
+be powered off when the child domains are powered off. The CPU cluster can be
+fashioned as a PM domain. When the CPU devices are powered off, the PM domain
+may be powered off.
+
+Device idle is reference counted by runtime PM. When there is no active need
+for the device, runtime PM invokes callbacks to suspend the parent domain.
+Generic PM domain (genpd) handles the hierarchy of devices, domains and the
+reference counting of objects leading to last man down and first man up in the
+domain. The CPU domains helper functions defines PM domains for each CPU
+cluster and attaches the CPU devices to the respective PM domains.
+
+Platform drivers may use the following API to register their CPU PM domains.
+
+of_setup_cpu_pd() -
+Provides a single step registration of the CPU PM domain and attach CPUs to
+the genpd. Platform drivers may additionally register callbacks for power_on
+and power_off operations for the PM domain.
+
+of_setup_cpu_pd_single() -
+Define PM domain for a single CPU and attach the CPU to its domain.
+
+
+CPU PM Domain governor
+----------------------
+
+CPUs have a unique ability to determine their next wakeup. CPUs may wake up
+for known timer interrupts and unknown interrupts from idle. Prediction
+algorithms and heuristic based algorithms like the Menu governor for cpuidle
+can determine the next wakeup of the CPU. However, determining the wakeup
+across a group of CPUs is a tough problem to solve.
+
+A simplistic approach would be to resort to known wakeups of the CPUs in
+determining the next wakeup of any CPU in the cluster. The CPU PM domain
+governor does just that. By looking into the tick device of the CPUs, the
+governor can determine the sleep time between the last CPU and the first
+scheduled wakeup of any CPU in that domain. This combined with the PM QoS
+requirement for CPU_DMA_LATENCY can be used to determine the deepest possible
+idle state of the CPU domain.
-- 
2.1.4

[RFC v3 09/12] drivers: firmware: psci: Allow OS Initiated suspend mode

[Lina Iyer]

PSCI firmware v1.0 onwards may support 2 different modes for
CPU_SUSPEND. Platform coordinated mode is the default and every firmware
should support it. The firmware shall also be the default mode.

With the kernel capable of deciding the state for CPU cluster and
coherency domains, the OS Initiated mode may now be used by the kernel,
provided the firmware supports it. SET_SUSPEND_MODE is a PSCI function
available on v1.0 onwards and can be used to set the mode in the
firmware.

Cc: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Lina Iyer <lina.iyer@linaro.org>
---
 drivers/firmware/psci.c   | 45 ++++++++++++++++++++++++++++++++++++++++++++-
 include/linux/psci.h      |  2 ++
 include/uapi/linux/psci.h |  5 +++++
 3 files changed, 51 insertions(+), 1 deletion(-)

diff --git a/drivers/firmware/psci.c b/drivers/firmware/psci.c
index f25cd79..03c084e 100644
--- a/drivers/firmware/psci.c
+++ b/drivers/firmware/psci.c
@@ -49,12 +49,19 @@
  * require cooperation with a Trusted OS driver.
  */
 static int resident_cpu = -1;
+static bool has_osi_pd;
+static bool psci_suspend_mode_is_osi;
 
 bool psci_tos_resident_on(int cpu)
 {
 	return cpu == resident_cpu;
 }
 
+bool psci_has_osi_pd_support(void)
+{
+	return has_osi_pd;
+}
+
 struct psci_operations psci_ops;
 
 typedef unsigned long (psci_fn)(unsigned long, unsigned long,
@@ -250,6 +257,26 @@ static int psci_system_suspend(unsigned long unused)
 			      virt_to_phys(cpu_resume), 0, 0);
 }
 
+int psci_set_suspend_mode_osi(bool enable)
+{
+	int ret;
+	int mode;
+
+	if (enable && !psci_has_osi_pd_support())
+		return -ENODEV;
+
+	if (enable == psci_suspend_mode_is_osi)
+		return 0;
+
+	mode = enable ? PSCI_1_0_SUSPEND_MODE_OSI : PSCI_1_0_SUSPEND_MODE_PC;
+	ret = invoke_psci_fn(PSCI_FN_NATIVE(1_0, SET_SUSPEND_MODE),
+			     mode, 0, 0);
+	if (!ret)
+		psci_suspend_mode_is_osi = enable;
+
+	return psci_to_linux_errno(ret);
+}
+
 static int psci_system_suspend_enter(suspend_state_t state)
 {
 	return cpu_suspend(0, psci_system_suspend);
@@ -443,10 +470,26 @@ out_put_node:
 	return err;
 }
 
+static int __init psci_1_0_init(struct device_node *np)
+{
+	int ret;
+
+	ret = psci_0_2_init(np);
+	if (ret)
+		return ret;
+
+	/* Check if PSCI OSI mode is available */
+	ret = psci_features(PSCI_FN_NATIVE(0_2, CPU_SUSPEND));
+	if (ret & PSCI_1_0_OS_INITIATED)
+		has_osi_pd = true;
+
+	return 0;
+}
+
 static const struct of_device_id const psci_of_match[] __initconst = {
 	{ .compatible = "arm,psci",	.data = psci_0_1_init},
 	{ .compatible = "arm,psci-0.2",	.data = psci_0_2_init},
-	{ .compatible = "arm,psci-1.0",	.data = psci_0_2_init},
+	{ .compatible = "arm,psci-1.0",	.data = psci_1_0_init},
 	{},
 };
 
diff --git a/include/linux/psci.h b/include/linux/psci.h
index 12c4865..deae633 100644
--- a/include/linux/psci.h
+++ b/include/linux/psci.h
@@ -23,6 +23,8 @@
 bool psci_tos_resident_on(int cpu);
 bool psci_power_state_loses_context(u32 state);
 bool psci_power_state_is_valid(u32 state);
+bool psci_has_osi_pd_support(void);
+int psci_set_suspend_mode_osi(bool enable);
 
 struct psci_operations {
 	int (*cpu_suspend)(u32 state, unsigned long entry_point);
diff --git a/include/uapi/linux/psci.h b/include/uapi/linux/psci.h
index 3d7a0fc..eaab6e3 100644
--- a/include/uapi/linux/psci.h
+++ b/include/uapi/linux/psci.h
@@ -50,6 +50,7 @@
 #define PSCI_1_0_FN_SYSTEM_SUSPEND		PSCI_0_2_FN(14)
 
 #define PSCI_1_0_FN64_SYSTEM_SUSPEND		PSCI_0_2_FN64(14)
+#define PSCI_1_0_FN64_SET_SUSPEND_MODE		PSCI_0_2_FN64(15)
 
 /* PSCI v0.2 power state encoding for CPU_SUSPEND function */
 #define PSCI_0_2_POWER_STATE_ID_MASK		0xffff
@@ -93,6 +94,10 @@
 #define PSCI_1_0_FEATURES_CPU_SUSPEND_PF_MASK	\
 			(0x1 << PSCI_1_0_FEATURES_CPU_SUSPEND_PF_SHIFT)
 
+#define PSCI_1_0_OS_INITIATED			BIT(0)
+#define PSCI_1_0_SUSPEND_MODE_PC		0
+#define PSCI_1_0_SUSPEND_MODE_OSI		1
+
 /* PSCI return values (inclusive of all PSCI versions) */
 #define PSCI_RET_SUCCESS			0
 #define PSCI_RET_NOT_SUPPORTED			-1
-- 
2.1.4

[RFC v3 09/12] drivers: firmware: psci: Allow OS Initiated suspend mode

[Lina Iyer]

PSCI firmware v1.0 onwards may support 2 different modes for
CPU_SUSPEND. Platform coordinated mode is the default and every firmware
should support it. The firmware shall also be the default mode.

With the kernel capable of deciding the state for CPU cluster and
coherency domains, the OS Initiated mode may now be used by the kernel,
provided the firmware supports it. SET_SUSPEND_MODE is a PSCI function
available on v1.0 onwards and can be used to set the mode in the
firmware.

Cc: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Lina Iyer <lina.iyer@linaro.org>
---
 drivers/firmware/psci.c   | 45 ++++++++++++++++++++++++++++++++++++++++++++-
 include/linux/psci.h      |  2 ++
 include/uapi/linux/psci.h |  5 +++++
 3 files changed, 51 insertions(+), 1 deletion(-)

diff --git a/drivers/firmware/psci.c b/drivers/firmware/psci.c
index f25cd79..03c084e 100644
--- a/drivers/firmware/psci.c
+++ b/drivers/firmware/psci.c
@@ -49,12 +49,19 @@
  * require cooperation with a Trusted OS driver.
  */
 static int resident_cpu = -1;
+static bool has_osi_pd;
+static bool psci_suspend_mode_is_osi;
 
 bool psci_tos_resident_on(int cpu)
 {
 	return cpu == resident_cpu;
 }
 
+bool psci_has_osi_pd_support(void)
+{
+	return has_osi_pd;
+}
+
 struct psci_operations psci_ops;
 
 typedef unsigned long (psci_fn)(unsigned long, unsigned long,
@@ -250,6 +257,26 @@ static int psci_system_suspend(unsigned long unused)
 			      virt_to_phys(cpu_resume), 0, 0);
 }
 
+int psci_set_suspend_mode_osi(bool enable)
+{
+	int ret;
+	int mode;
+
+	if (enable && !psci_has_osi_pd_support())
+		return -ENODEV;
+
+	if (enable == psci_suspend_mode_is_osi)
+		return 0;
+
+	mode = enable ? PSCI_1_0_SUSPEND_MODE_OSI : PSCI_1_0_SUSPEND_MODE_PC;
+	ret = invoke_psci_fn(PSCI_FN_NATIVE(1_0, SET_SUSPEND_MODE),
+			     mode, 0, 0);
+	if (!ret)
+		psci_suspend_mode_is_osi = enable;
+
+	return psci_to_linux_errno(ret);
+}
+
 static int psci_system_suspend_enter(suspend_state_t state)
 {
 	return cpu_suspend(0, psci_system_suspend);
@@ -443,10 +470,26 @@ out_put_node:
 	return err;
 }
 
+static int __init psci_1_0_init(struct device_node *np)
+{
+	int ret;
+
+	ret = psci_0_2_init(np);
+	if (ret)
+		return ret;
+
+	/* Check if PSCI OSI mode is available */
+	ret = psci_features(PSCI_FN_NATIVE(0_2, CPU_SUSPEND));
+	if (ret & PSCI_1_0_OS_INITIATED)
+		has_osi_pd = true;
+
+	return 0;
+}
+
 static const struct of_device_id const psci_of_match[] __initconst = {
 	{ .compatible = "arm,psci",	.data = psci_0_1_init},
 	{ .compatible = "arm,psci-0.2",	.data = psci_0_2_init},
-	{ .compatible = "arm,psci-1.0",	.data = psci_0_2_init},
+	{ .compatible = "arm,psci-1.0",	.data = psci_1_0_init},
 	{},
 };
 
diff --git a/include/linux/psci.h b/include/linux/psci.h
index 12c4865..deae633 100644
--- a/include/linux/psci.h
+++ b/include/linux/psci.h
@@ -23,6 +23,8 @@
 bool psci_tos_resident_on(int cpu);
 bool psci_power_state_loses_context(u32 state);
 bool psci_power_state_is_valid(u32 state);
+bool psci_has_osi_pd_support(void);
+int psci_set_suspend_mode_osi(bool enable);
 
 struct psci_operations {
 	int (*cpu_suspend)(u32 state, unsigned long entry_point);
diff --git a/include/uapi/linux/psci.h b/include/uapi/linux/psci.h
index 3d7a0fc..eaab6e3 100644
--- a/include/uapi/linux/psci.h
+++ b/include/uapi/linux/psci.h
@@ -50,6 +50,7 @@
 #define PSCI_1_0_FN_SYSTEM_SUSPEND		PSCI_0_2_FN(14)
 
 #define PSCI_1_0_FN64_SYSTEM_SUSPEND		PSCI_0_2_FN64(14)
+#define PSCI_1_0_FN64_SET_SUSPEND_MODE		PSCI_0_2_FN64(15)
 
 /* PSCI v0.2 power state encoding for CPU_SUSPEND function */
 #define PSCI_0_2_POWER_STATE_ID_MASK		0xffff
@@ -93,6 +94,10 @@
 #define PSCI_1_0_FEATURES_CPU_SUSPEND_PF_MASK	\
 			(0x1 << PSCI_1_0_FEATURES_CPU_SUSPEND_PF_SHIFT)
 
+#define PSCI_1_0_OS_INITIATED			BIT(0)
+#define PSCI_1_0_SUSPEND_MODE_PC		0
+#define PSCI_1_0_SUSPEND_MODE_OSI		1
+
 /* PSCI return values (inclusive of all PSCI versions) */
 #define PSCI_RET_SUCCESS			0
 #define PSCI_RET_NOT_SUPPORTED			-1
-- 
2.1.4

[RFC v3 10/12] ARM64: psci: Support cluster idle states for OS-Initiated

[Lina Iyer]

PSCI OS initiated firmware may allow Linux to determine the state of the
CPU cluster and the cluster at coherency level to enter idle states when
there are no active CPUs. Since Linux has a better idea of the QoS and
the wakeup pattern of the CPUs, the cluster idle states may be better
determined by the OS instead of the firmware.

The last CPU entering idle in a cluster, is responsible for selecting
the state of the cluster. Only one CPU in a cluster may provide the
cluster idle state to the firmware. Similarly, the last CPU in the
system may provide the state of the coherency domain along with the
cluster and the CPU state IDs.

Utilize the CPU PM domain framework's helper functions to build up the
hierarchy of cluster topology using Generic PM domains. We provide
callbacks for domain power_on and power_off. By appending the state IDs
at each domain level in the -power_off() callbacks, we build up a
composite state ID that can be passed onto the firmware to idle the CPU,
the cluster and the coherency interface.

Cc: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Lina Iyer <lina.iyer@linaro.org>
---
 arch/arm64/kernel/psci.c | 46 +++++++++++++++++++++++++++++++++++++++++++---
 1 file changed, 43 insertions(+), 3 deletions(-)

diff --git a/arch/arm64/kernel/psci.c b/arch/arm64/kernel/psci.c
index f67f35b..75b1707 100644
--- a/arch/arm64/kernel/psci.c
+++ b/arch/arm64/kernel/psci.c
@@ -15,6 +15,7 @@
 
 #define pr_fmt(fmt) "psci: " fmt
 
+#include <linux/cpu_domains.h>
 #include <linux/init.h>
 #include <linux/of.h>
 #include <linux/smp.h>
@@ -31,6 +32,24 @@
 #include <asm/suspend.h>
 
 static DEFINE_PER_CPU_READ_MOSTLY(u32 *, psci_power_state);
+static DEFINE_PER_CPU(u32, cluster_state_id);
+
+static inline u32 psci_get_composite_state_id(u32 cpu_state)
+{
+	return cpu_state | this_cpu_read(cluster_state_id);
+}
+
+static inline void psci_reset_composite_state_id(void)
+{
+	this_cpu_write(cluster_state_id, 0);
+}
+
+static int psci_pd_power_off(u32 state_idx, u32 param,
+		const struct cpumask *mask)
+{
+	__this_cpu_add(cluster_state_id, param);
+	return 0;
+}
 
 static int __maybe_unused cpu_psci_cpu_init_idle(unsigned int cpu)
 {
@@ -89,6 +108,19 @@ static int __maybe_unused cpu_psci_cpu_init_idle(unsigned int cpu)
 	}
 	/* Idle states parsed correctly, initialize per-cpu pointer */
 	per_cpu(psci_power_state, cpu) = psci_states;
+
+	if (psci_has_osi_pd_support()) {
+		const struct cpu_pd_ops psci_pd_ops = {
+			.power_off = psci_pd_power_off,
+		};
+
+		ret = of_setup_cpu_pd_single(cpu, &psci_pd_ops);
+		if (!ret)
+			ret = psci_set_suspend_mode_osi(true);
+		if (ret)
+			pr_warn("CPU%d: Error setting PSCI OSI mode\n", cpu);
+	}
+
 	return 0;
 
 free_mem:
@@ -117,6 +149,8 @@ static int cpu_psci_cpu_boot(unsigned int cpu)
 	if (err)
 		pr_err("failed to boot CPU%d (%d)\n", cpu, err);
 
+	/* Reset CPU cluster states */
+	psci_reset_composite_state_id();
 	return err;
 }
 
@@ -181,15 +215,16 @@ static int cpu_psci_cpu_kill(unsigned int cpu)
 static int psci_suspend_finisher(unsigned long index)
 {
 	u32 *state = __this_cpu_read(psci_power_state);
+	u32 ext_state = psci_get_composite_state_id(state[index - 1]);
 
-	return psci_ops.cpu_suspend(state[index - 1],
-				    virt_to_phys(cpu_resume));
+	return psci_ops.cpu_suspend(ext_state, virt_to_phys(cpu_resume));
 }
 
 static int __maybe_unused cpu_psci_cpu_suspend(unsigned long index)
 {
 	int ret;
 	u32 *state = __this_cpu_read(psci_power_state);
+	u32 ext_state = psci_get_composite_state_id(state[index - 1]);
 	/*
 	 * idle state index 0 corresponds to wfi, should never be called
 	 * from the cpu_suspend operations
@@ -198,10 +233,15 @@ static int __maybe_unused cpu_psci_cpu_suspend(unsigned long index)
 		return -EINVAL;
 
 	if (!psci_power_state_loses_context(state[index - 1]))
-		ret = psci_ops.cpu_suspend(state[index - 1], 0);
+		ret = psci_ops.cpu_suspend(ext_state, 0);
 	else
 		ret = cpu_suspend(index, psci_suspend_finisher);
 
+	/*
+	 * Clear the CPU's cluster states, we start afresh after coming
+	 * out of idle.
+	 */
+	psci_reset_composite_state_id();
 	return ret;
 }
 
-- 
2.1.4

[RFC v3 10/12] ARM64: psci: Support cluster idle states for OS-Initiated

[Lina Iyer]

PSCI OS initiated firmware may allow Linux to determine the state of the
CPU cluster and the cluster at coherency level to enter idle states when
there are no active CPUs. Since Linux has a better idea of the QoS and
the wakeup pattern of the CPUs, the cluster idle states may be better
determined by the OS instead of the firmware.

The last CPU entering idle in a cluster, is responsible for selecting
the state of the cluster. Only one CPU in a cluster may provide the
cluster idle state to the firmware. Similarly, the last CPU in the
system may provide the state of the coherency domain along with the
cluster and the CPU state IDs.

Utilize the CPU PM domain framework's helper functions to build up the
hierarchy of cluster topology using Generic PM domains. We provide
callbacks for domain power_on and power_off. By appending the state IDs
at each domain level in the -power_off() callbacks, we build up a
composite state ID that can be passed onto the firmware to idle the CPU,
the cluster and the coherency interface.

Cc: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Lina Iyer <lina.iyer@linaro.org>
---
 arch/arm64/kernel/psci.c | 46 +++++++++++++++++++++++++++++++++++++++++++---
 1 file changed, 43 insertions(+), 3 deletions(-)

diff --git a/arch/arm64/kernel/psci.c b/arch/arm64/kernel/psci.c
index f67f35b..75b1707 100644
--- a/arch/arm64/kernel/psci.c
+++ b/arch/arm64/kernel/psci.c
@@ -15,6 +15,7 @@
 
 #define pr_fmt(fmt) "psci: " fmt
 
+#include <linux/cpu_domains.h>
 #include <linux/init.h>
 #include <linux/of.h>
 #include <linux/smp.h>
@@ -31,6 +32,24 @@
 #include <asm/suspend.h>
 
 static DEFINE_PER_CPU_READ_MOSTLY(u32 *, psci_power_state);
+static DEFINE_PER_CPU(u32, cluster_state_id);
+
+static inline u32 psci_get_composite_state_id(u32 cpu_state)
+{
+	return cpu_state | this_cpu_read(cluster_state_id);
+}
+
+static inline void psci_reset_composite_state_id(void)
+{
+	this_cpu_write(cluster_state_id, 0);
+}
+
+static int psci_pd_power_off(u32 state_idx, u32 param,
+		const struct cpumask *mask)
+{
+	__this_cpu_add(cluster_state_id, param);
+	return 0;
+}
 
 static int __maybe_unused cpu_psci_cpu_init_idle(unsigned int cpu)
 {
@@ -89,6 +108,19 @@ static int __maybe_unused cpu_psci_cpu_init_idle(unsigned int cpu)
 	}
 	/* Idle states parsed correctly, initialize per-cpu pointer */
 	per_cpu(psci_power_state, cpu) = psci_states;
+
+	if (psci_has_osi_pd_support()) {
+		const struct cpu_pd_ops psci_pd_ops = {
+			.power_off = psci_pd_power_off,
+		};
+
+		ret = of_setup_cpu_pd_single(cpu, &psci_pd_ops);
+		if (!ret)
+			ret = psci_set_suspend_mode_osi(true);
+		if (ret)
+			pr_warn("CPU%d: Error setting PSCI OSI mode\n", cpu);
+	}
+
 	return 0;
 
 free_mem:
@@ -117,6 +149,8 @@ static int cpu_psci_cpu_boot(unsigned int cpu)
 	if (err)
 		pr_err("failed to boot CPU%d (%d)\n", cpu, err);
 
+	/* Reset CPU cluster states */
+	psci_reset_composite_state_id();
 	return err;
 }
 
@@ -181,15 +215,16 @@ static int cpu_psci_cpu_kill(unsigned int cpu)
 static int psci_suspend_finisher(unsigned long index)
 {
 	u32 *state = __this_cpu_read(psci_power_state);
+	u32 ext_state = psci_get_composite_state_id(state[index - 1]);
 
-	return psci_ops.cpu_suspend(state[index - 1],
-				    virt_to_phys(cpu_resume));
+	return psci_ops.cpu_suspend(ext_state, virt_to_phys(cpu_resume));
 }
 
 static int __maybe_unused cpu_psci_cpu_suspend(unsigned long index)
 {
 	int ret;
 	u32 *state = __this_cpu_read(psci_power_state);
+	u32 ext_state = psci_get_composite_state_id(state[index - 1]);
 	/*
 	 * idle state index 0 corresponds to wfi, should never be called
 	 * from the cpu_suspend operations
@@ -198,10 +233,15 @@ static int __maybe_unused cpu_psci_cpu_suspend(unsigned long index)
 		return -EINVAL;
 
 	if (!psci_power_state_loses_context(state[index - 1]))
-		ret = psci_ops.cpu_suspend(state[index - 1], 0);
+		ret = psci_ops.cpu_suspend(ext_state, 0);
 	else
 		ret = cpu_suspend(index, psci_suspend_finisher);
 
+	/*
+	 * Clear the CPU's cluster states, we start afresh after coming
+	 * out of idle.
+	 */
+	psci_reset_composite_state_id();
 	return ret;
 }
 
-- 
2.1.4

[RFC v3 11/12] ARM64: dts: Add PSCI cpuidle support for MSM8916

[Lina Iyer]

Add device bindings for CPUs to suspend using PSCI as the enable-method.

Cc: <devicetree@vger.kernel.org>
Signed-off-by: Lina Iyer <lina.iyer@linaro.org>
---
 arch/arm64/boot/dts/qcom/msm8916.dtsi | 24 ++++++++++++++++++++++++
 1 file changed, 24 insertions(+)

diff --git a/arch/arm64/boot/dts/qcom/msm8916.dtsi b/arch/arm64/boot/dts/qcom/msm8916.dtsi
index 9153214..b7839a8 100644
--- a/arch/arm64/boot/dts/qcom/msm8916.dtsi
+++ b/arch/arm64/boot/dts/qcom/msm8916.dtsi
@@ -61,27 +61,51 @@
 			device_type = "cpu";
 			compatible = "arm,cortex-a53", "arm,armv8";
 			reg = <0x0>;
+			enable-method = "psci";
+			cpu-idle-states = <&CPU_SPC>;
 		};
 
 		CPU1: cpu@1 {
 			device_type = "cpu";
 			compatible = "arm,cortex-a53", "arm,armv8";
 			reg = <0x1>;
+			enable-method = "psci";
+			cpu-idle-states = <&CPU_SPC>;
 		};
 
 		CPU2: cpu@2 {
 			device_type = "cpu";
 			compatible = "arm,cortex-a53", "arm,armv8";
 			reg = <0x2>;
+			enable-method = "psci";
+			cpu-idle-states = <&CPU_SPC>;
 		};
 
 		CPU3: cpu@3 {
 			device_type = "cpu";
 			compatible = "arm,cortex-a53", "arm,armv8";
 			reg = <0x3>;
+			enable-method = "psci";
+			cpu-idle-states = <&CPU_SPC>;
+		};
+
+		idle-states {
+			CPU_SPC: spc {
+				compatible = "arm,idle-state";
+				arm,psci-suspend-param = <0x40000002>;
+				entry-latency-us = <130>;
+				exit-latency-us = <150>;
+				min-residency-us = <2000>;
+				local-timer-stop;
+			};
 		};
 	};
 
+	psci {
+		compatible = "arm,psci-1.0";
+		method = "smc";
+	};
+
 	timer {
 		compatible = "arm,armv8-timer";
 		interrupts = <GIC_PPI 2 (GIC_CPU_MASK_SIMPLE(4) | IRQ_TYPE_LEVEL_LOW)>,
-- 
2.1.4

[RFC v3 11/12] ARM64: dts: Add PSCI cpuidle support for MSM8916

[Lina Iyer]

Add device bindings for CPUs to suspend using PSCI as the enable-method.

Cc: <devicetree@vger.kernel.org>
Signed-off-by: Lina Iyer <lina.iyer@linaro.org>
---
 arch/arm64/boot/dts/qcom/msm8916.dtsi | 24 ++++++++++++++++++++++++
 1 file changed, 24 insertions(+)

diff --git a/arch/arm64/boot/dts/qcom/msm8916.dtsi b/arch/arm64/boot/dts/qcom/msm8916.dtsi
index 9153214..b7839a8 100644
--- a/arch/arm64/boot/dts/qcom/msm8916.dtsi
+++ b/arch/arm64/boot/dts/qcom/msm8916.dtsi
@@ -61,27 +61,51 @@
 			device_type = "cpu";
 			compatible = "arm,cortex-a53", "arm,armv8";
 			reg = <0x0>;
+			enable-method = "psci";
+			cpu-idle-states = <&CPU_SPC>;
 		};
 
 		CPU1: cpu at 1 {
 			device_type = "cpu";
 			compatible = "arm,cortex-a53", "arm,armv8";
 			reg = <0x1>;
+			enable-method = "psci";
+			cpu-idle-states = <&CPU_SPC>;
 		};
 
 		CPU2: cpu at 2 {
 			device_type = "cpu";
 			compatible = "arm,cortex-a53", "arm,armv8";
 			reg = <0x2>;
+			enable-method = "psci";
+			cpu-idle-states = <&CPU_SPC>;
 		};
 
 		CPU3: cpu at 3 {
 			device_type = "cpu";
 			compatible = "arm,cortex-a53", "arm,armv8";
 			reg = <0x3>;
+			enable-method = "psci";
+			cpu-idle-states = <&CPU_SPC>;
+		};
+
+		idle-states {
+			CPU_SPC: spc {
+				compatible = "arm,idle-state";
+				arm,psci-suspend-param = <0x40000002>;
+				entry-latency-us = <130>;
+				exit-latency-us = <150>;
+				min-residency-us = <2000>;
+				local-timer-stop;
+			};
 		};
 	};
 
+	psci {
+		compatible = "arm,psci-1.0";
+		method = "smc";
+	};
+
 	timer {
 		compatible = "arm,armv8-timer";
 		interrupts = <GIC_PPI 2 (GIC_CPU_MASK_SIMPLE(4) | IRQ_TYPE_LEVEL_LOW)>,
-- 
2.1.4

[RFC v3 12/12] ARM64: dts: Define CPU power domain for MSM8916

[Lina Iyer]

Define power domain and the power states for the domain as defined by
the PSCI firmware. The 8916 firmware supports OS initiated method of
powering off the CPU clusters.

Cc: <devicetree@vger.kernel.org>
Signed-off-by: Lina Iyer <lina.iyer@linaro.org>
---
 arch/arm64/boot/dts/qcom/msm8916.dtsi | 25 +++++++++++++++++++++++++
 1 file changed, 25 insertions(+)

diff --git a/arch/arm64/boot/dts/qcom/msm8916.dtsi b/arch/arm64/boot/dts/qcom/msm8916.dtsi
index b7839a8..62dade8 100644
--- a/arch/arm64/boot/dts/qcom/msm8916.dtsi
+++ b/arch/arm64/boot/dts/qcom/msm8916.dtsi
@@ -63,6 +63,7 @@
 			reg = <0x0>;
 			enable-method = "psci";
 			cpu-idle-states = <&CPU_SPC>;
+			power-domains = <&CPU_PD>;
 		};
 
 		CPU1: cpu@1 {
@@ -71,6 +72,7 @@
 			reg = <0x1>;
 			enable-method = "psci";
 			cpu-idle-states = <&CPU_SPC>;
+			power-domains = <&CPU_PD>;
 		};
 
 		CPU2: cpu@2 {
@@ -79,6 +81,7 @@
 			reg = <0x2>;
 			enable-method = "psci";
 			cpu-idle-states = <&CPU_SPC>;
+			power-domains = <&CPU_PD>;
 		};
 
 		CPU3: cpu@3 {
@@ -87,6 +90,7 @@
 			reg = <0x3>;
 			enable-method = "psci";
 			cpu-idle-states = <&CPU_SPC>;
+			power-domains = <&CPU_PD>;
 		};
 
 		idle-states {
@@ -101,6 +105,27 @@
 		};
 	};
 
+	CPU_PD: cpu-pd@0 {
+		#power-domain-cells = <0>;
+		power-states = <&CLUSTER_RET>, <&CLUSTER_PWR_DWN>;
+	};
+
+	pd-power-states {
+		CLUSTER_RET: power-state@1 {
+			state-param = <0x1000010>;
+			entry-latency-us = <500>;
+			exit-latency-us = <500>;
+			residency-us = <2000>;
+		 };
+
+		CLUSTER_PWR_DWN: power-state@2 {
+			state-param = <0x1000030>;
+			entry-latency-us = <2000>;
+			exit-latency-us = <2000>;
+			residency-us = <6000>;
+		};
+	};
+
 	psci {
 		compatible = "arm,psci-1.0";
 		method = "smc";
-- 
2.1.4

[RFC v3 12/12] ARM64: dts: Define CPU power domain for MSM8916

[Lina Iyer]

Define power domain and the power states for the domain as defined by
the PSCI firmware. The 8916 firmware supports OS initiated method of
powering off the CPU clusters.

Cc: <devicetree@vger.kernel.org>
Signed-off-by: Lina Iyer <lina.iyer@linaro.org>
---
 arch/arm64/boot/dts/qcom/msm8916.dtsi | 25 +++++++++++++++++++++++++
 1 file changed, 25 insertions(+)

diff --git a/arch/arm64/boot/dts/qcom/msm8916.dtsi b/arch/arm64/boot/dts/qcom/msm8916.dtsi
index b7839a8..62dade8 100644
--- a/arch/arm64/boot/dts/qcom/msm8916.dtsi
+++ b/arch/arm64/boot/dts/qcom/msm8916.dtsi
@@ -63,6 +63,7 @@
 			reg = <0x0>;
 			enable-method = "psci";
 			cpu-idle-states = <&CPU_SPC>;
+			power-domains = <&CPU_PD>;
 		};
 
 		CPU1: cpu at 1 {
@@ -71,6 +72,7 @@
 			reg = <0x1>;
 			enable-method = "psci";
 			cpu-idle-states = <&CPU_SPC>;
+			power-domains = <&CPU_PD>;
 		};
 
 		CPU2: cpu at 2 {
@@ -79,6 +81,7 @@
 			reg = <0x2>;
 			enable-method = "psci";
 			cpu-idle-states = <&CPU_SPC>;
+			power-domains = <&CPU_PD>;
 		};
 
 		CPU3: cpu at 3 {
@@ -87,6 +90,7 @@
 			reg = <0x3>;
 			enable-method = "psci";
 			cpu-idle-states = <&CPU_SPC>;
+			power-domains = <&CPU_PD>;
 		};
 
 		idle-states {
@@ -101,6 +105,27 @@
 		};
 	};
 
+	CPU_PD: cpu-pd at 0 {
+		#power-domain-cells = <0>;
+		power-states = <&CLUSTER_RET>, <&CLUSTER_PWR_DWN>;
+	};
+
+	pd-power-states {
+		CLUSTER_RET: power-state at 1 {
+			state-param = <0x1000010>;
+			entry-latency-us = <500>;
+			exit-latency-us = <500>;
+			residency-us = <2000>;
+		 };
+
+		CLUSTER_PWR_DWN: power-state at 2 {
+			state-param = <0x1000030>;
+			entry-latency-us = <2000>;
+			exit-latency-us = <2000>;
+			residency-us = <6000>;
+		};
+	};
+
 	psci {
 		compatible = "arm,psci-1.0";
 		method = "smc";
-- 
2.1.4

Re: [BUG FIX] PM / cpu_domains: Check for NULL callbacks

[Lina Iyer]

Ignore this patch pls. This change has been folded in.

Thanks,
Lina

On Tue, Mar 01 2016 at 14:15 -0700, Lina Iyer wrote:
>Check for NULL platform callback before calling.
>
>Signed-off-by: Lina Iyer <lina.iyer@linaro.org>
>---
> drivers/base/power/cpu_domains.c | 10 ++++++++--
> 1 file changed, 8 insertions(+), 2 deletions(-)
>
>diff --git a/drivers/base/power/cpu_domains.c b/drivers/base/power/cpu_domains.c
>index 7069411..bcaa474 100644
>--- a/drivers/base/power/cpu_domains.c
>+++ b/drivers/base/power/cpu_domains.c
>@@ -157,16 +157,22 @@ static int cpu_pd_power_on(struct generic_pm_domain *genpd)
> {
> 	struct cpu_pm_domain *pd = to_cpu_pd(genpd);
>
>-	return pd->ops.power_on();
>+	if (pd->ops.power_on)
>+		return pd->ops.power_on();
>+
>+	return 0;
> }
>
> static int cpu_pd_power_off(struct generic_pm_domain *genpd)
> {
> 	struct cpu_pm_domain *pd = to_cpu_pd(genpd);
>
>-	return pd->ops.power_off(genpd->state_idx,
>+	if (pd->ops.power_off)
>+		return pd->ops.power_off(genpd->state_idx,
> 			genpd->states[genpd->state_idx].param,
> 			pd->cpus);
>+
>+	return 0;
> }
>
> /**
>-- 
>2.1.4
>

[BUG FIX] PM / cpu_domains: Check for NULL callbacks

[Lina Iyer]

Ignore this patch pls. This change has been folded in.

Thanks,
Lina

On Tue, Mar 01 2016 at 14:15 -0700, Lina Iyer wrote:
>Check for NULL platform callback before calling.
>
>Signed-off-by: Lina Iyer <lina.iyer@linaro.org>
>---
> drivers/base/power/cpu_domains.c | 10 ++++++++--
> 1 file changed, 8 insertions(+), 2 deletions(-)
>
>diff --git a/drivers/base/power/cpu_domains.c b/drivers/base/power/cpu_domains.c
>index 7069411..bcaa474 100644
>--- a/drivers/base/power/cpu_domains.c
>+++ b/drivers/base/power/cpu_domains.c
>@@ -157,16 +157,22 @@ static int cpu_pd_power_on(struct generic_pm_domain *genpd)
> {
> 	struct cpu_pm_domain *pd = to_cpu_pd(genpd);
>
>-	return pd->ops.power_on();
>+	if (pd->ops.power_on)
>+		return pd->ops.power_on();
>+
>+	return 0;
> }
>
> static int cpu_pd_power_off(struct generic_pm_domain *genpd)
> {
> 	struct cpu_pm_domain *pd = to_cpu_pd(genpd);
>
>-	return pd->ops.power_off(genpd->state_idx,
>+	if (pd->ops.power_off)
>+		return pd->ops.power_off(genpd->state_idx,
> 			genpd->states[genpd->state_idx].param,
> 			pd->cpus);
>+
>+	return 0;
> }
>
> /**
>-- 
>2.1.4
>

Re: [RFC v3 02/12] PM / Domains: Support IRQ safe PM domains

[Kevin Hilman]

Lina Iyer <lina.iyer@linaro.org> writes:

> Generic Power Domains currently support turning on/off only in process
> context. This prevents the usage of PM domains for domains that could be
> powered on/off in a context where IRQs are disabled. Many such domains
> exist today and do not get powered off, when the IRQ safe devices in
> that domain are powered off, because of this limitation.
>
> However, not all domains can operate in IRQ safe contexts. Genpd
> therefore, has to support both cases where the domain may or may not
> operate in IRQ safe contexts. Configuring genpd to use an appropriate
> lock for that domain, would allow domains that have IRQ safe devices to
> runtime suspend and resume, in atomic context.
>
> To achieve domain specific locking, set the domain's ->flag to
> GENPD_FLAG_IRQ_SAFE while defining the domain. This indicates that genpd
> should use a spinlock instead of a mutex for locking the domain. Locking
> is abstracted through genpd_lock() and genpd_unlock() functions that use
> the flag to determine the appropriate lock to be used for that domain.
>
> Domains that have lower latency to suspend and resume and can operate
> with IRQs disabled may now be able to save power, when the component
> devices and sub-domains are idle at runtime.
>
> The restriction this imposes on the domain hierarchy is that non-IRQ
> safe domains may not have IRQ-safe subdomains, but IRQ safe domains may
> have IRQ safe and non-IRQ safe domains and devices.

I'm starting to think we also need a patch to the debugfg
pm_genpd_summary that will show which domains and which devices are IRQ
safe.

> Cc: Ulf Hansson <ulf.hansson@linaro.org>
> Cc: Kevin Hilman <khilman@linaro.org>
> Cc: Rafael J. Wysocki <rjw@rjwysocki.net>
> Cc: Geert Uytterhoeven <geert@linux-m68k.org>
> Cc: Krzysztof Kozłowski <k.kozlowski@samsung.com>
> Signed-off-by: Lina Iyer <lina.iyer@linaro.org>
> ---
>  Documentation/power/devices.txt |  12 ++++-
>  drivers/base/power/domain.c     | 105 ++++++++++++++++++++++++++++++++++++----
>  include/linux/pm_domain.h       |  11 ++++-
>  3 files changed, 117 insertions(+), 11 deletions(-)
>
> diff --git a/Documentation/power/devices.txt b/Documentation/power/devices.txt
> index 8ba6625..a622136 100644
> --- a/Documentation/power/devices.txt
> +++ b/Documentation/power/devices.txt
> @@ -607,7 +607,17 @@ individually.  Instead, a set of devices sharing a power resource can be put
>  into a low-power state together at the same time by turning off the shared
>  power resource.  Of course, they also need to be put into the full-power state
>  together, by turning the shared power resource on.  A set of devices with this
> -property is often referred to as a power domain.
> +property is often referred to as a power domain. A power domain may also be
> +nested inside another power domain.
> +
> +Devices, by default, operate in process context. If a device can operate in

Not device(s), but runtime PM callbacks for devices are what happen in
process context by default.

> +IRQ safe context that has to be explicitly indicated by setting the irq_safe
> +boolean inside struct generic_pm_domain to be true.

Maybe reference pm_runtime.txt documentation where this is described in
more detail.

> Power domains by default,
> +operate in process context but could have devices that are IRQ safe. Such
> +power domains cannot be powered on/off during runtime PM.

because...  ?

> On the other hand,
> +IRQ safe PM domains that have IRQ safe devices may be powered off when all
> +the devices are in idle. An IRQ safe domain may only be attached as a
> +subdomain to another IRQ safe domain.

The documentation should describe these limitations more, and the
reasons.

Also, this whole new paragraph you added should probably be the last
paragraph in this section, rather than between these two.

Maybe add a sub-section about IRQ safe domains and their limitations.

>  Support for power domains is provided through the pm_domain field of struct
>  device.  This field is a pointer to an object of type struct dev_pm_domain,
> diff --git a/drivers/base/power/domain.c b/drivers/base/power/domain.c
> index 20533d9..9541d80 100644
> --- a/drivers/base/power/domain.c
> +++ b/drivers/base/power/domain.c
> @@ -75,11 +75,59 @@ static const struct genpd_lock_fns genpd_mtx_fns  = {
>  	.unlock = genpd_unlock_mtx,
>  };
>  
> +static void genpd_lock_spin(struct generic_pm_domain *genpd)
> +	__acquires(&genpd->slock)
> +{
> +	unsigned long flags;
> +
> +	spin_lock_irqsave(&genpd->slock, flags);
> +	genpd->lock_flags = flags;
> +}
> +
> +static void genpd_lock_nested_spin(struct generic_pm_domain *genpd,
> +					int depth)
> +	__acquires(&genpd->slock)
> +{
> +	unsigned long flags;
> +
> +	spin_lock_irqsave_nested(&genpd->slock, flags, depth);
> +	genpd->lock_flags = flags;
> +}
> +
> +static int genpd_lock_interruptible_spin(struct generic_pm_domain *genpd)
> +	__acquires(&genpd->slock)
> +{
> +	unsigned long flags;
> +
> +	spin_lock_irqsave(&genpd->slock, flags);
> +	genpd->lock_flags = flags;
> +	return 0;
> +}
> +
> +static void genpd_unlock_spin(struct generic_pm_domain *genpd)
> +	__releases(&genpd->slock)
> +{
> +	spin_unlock_irqrestore(&genpd->slock, genpd->lock_flags);
> +}
> +
> +static const struct genpd_lock_fns genpd_spin_fns = {
> +	.lock = genpd_lock_spin,
> +	.lock_nested = genpd_lock_nested_spin,
> +	.lock_interruptible = genpd_lock_interruptible_spin,
> +	.unlock = genpd_unlock_spin,
> +};
> +
>  #define genpd_lock(p)			p->lock_fns->lock(p)
>  #define genpd_lock_nested(p, d)		p->lock_fns->lock_nested(p, d)
>  #define genpd_lock_interruptible(p)	p->lock_fns->lock_interruptible(p)
>  #define genpd_unlock(p)			p->lock_fns->unlock(p)
>  
> +static inline bool irq_safe_dev_in_no_sleep_domain(struct device *dev,
> +		struct generic_pm_domain *genpd)
> +{
> +	return dev->power.irq_safe && !genpd->irq_safe;
> +}
> +
>  /*
>   * Get the generic PM domain for a particular struct device.
>   * This validates the struct device pointer, the PM domain pointer,
> @@ -356,8 +404,17 @@ static int genpd_poweroff(struct generic_pm_domain *genpd, bool is_async)
>  		if (stat > PM_QOS_FLAGS_NONE)
>  			return -EBUSY;
>  
> -		if (!pm_runtime_suspended(pdd->dev) || pdd->dev->power.irq_safe)
> +		/*
> +		 * We do not want to power off the domain if the device is
> +		 * not suspended or an IRQ safe device is part of this
> +		 * non-IRQ safe domain.
> +		 */
> +		if (!pm_runtime_suspended(pdd->dev) ||
> +			irq_safe_dev_in_no_sleep_domain(pdd->dev, genpd))
>  			not_suspended++;
> +		WARN_ONCE(irq_safe_dev_in_no_sleep_domain(pdd->dev, genpd),
> +				"PM domain %s will not be powered off\n",
> +				genpd->name);

This WARN should include why.  "...because it contains IRQ safe
devices." or something similar, so it gives users a hint about what's
going on.

>  	}
>  
>  	if (not_suspended > 1 || (not_suspended == 1 && is_async))
> @@ -473,10 +530,13 @@ static int pm_genpd_runtime_suspend(struct device *dev)
>  	}
>  
>  	/*
> -	 * If power.irq_safe is set, this routine will be run with interrupts
> -	 * off, so it can't use mutexes.
> +	 * If power.irq_safe is set, this routine may be run with
> +	 * IRQ disabled, so suspend only if the power domain is

s/IRQ/IRQs/ (though I'm not sure why you changed from "interrupts off")

> +	 * irq_safe.
>  	 */
> -	if (dev->power.irq_safe)
> +	WARN_ONCE(irq_safe_dev_in_no_sleep_domain(dev, genpd),
> +			"genpd %s will not be powered off\n", genpd->name);

again, add why.

> +	if (irq_safe_dev_in_no_sleep_domain(dev, genpd))
>  		return 0;
>  
>  	genpd_lock(genpd);
> @@ -510,8 +570,11 @@ static int pm_genpd_runtime_resume(struct device *dev)
>  	if (IS_ERR(genpd))
>  		return -EINVAL;
>  
> -	/* If power.irq_safe, the PM domain is never powered off. */
> -	if (dev->power.irq_safe) {
> +	/*
> +	 * As we don't power off a non IRQ safe domain, which holds
> +	 * an IRQ safe device, we don't need to restore power to it.
> +	 */
> +	if (dev->power.irq_safe && !genpd->irq_safe) {
>  		timed = false;
>  		goto out;
>  	}
> @@ -1394,6 +1457,17 @@ int pm_genpd_add_subdomain(struct generic_pm_domain *genpd,
>  	    || genpd == subdomain)
>  		return -EINVAL;
>  
> +	/*
> +	 * If the domain can be powered on/off in an IRQ safe
> +	 * context, ensure that the subdomain can also be
> +	 * powered on/off in that context.
> +	 */
> +	if (!genpd->irq_safe && subdomain->irq_safe) {
> +		WARN("Parent %s of subdomain %s must be IRQ safe\n",
> +				genpd->name, subdomain->name);
> +		return -EINVAL;
> +	}
> +
>  	link = kzalloc(sizeof(*link), GFP_KERNEL);
>  	if (!link)
>  		return -ENOMEM;
> @@ -1610,6 +1684,19 @@ static int of_genpd_device_parse_states(struct device_node *np,
>  	return 0;
>  }
>  
> +static void genpd_lock_init(struct generic_pm_domain *genpd)
> +{
> +	if (genpd->flags & GENPD_FLAG_IRQ_SAFE) {
> +		spin_lock_init(&genpd->slock);
> +		genpd->irq_safe = true;
> +		genpd->lock_fns = &genpd_spin_fns;
> +	} else {
> +		mutex_init(&genpd->mlock);
> +		genpd->irq_safe = false;
> +		genpd->lock_fns = &genpd_mtx_fns;
> +	}
> +}
> +
>  /**
>   * pm_genpd_init - Initialize a generic I/O PM domain object.
>   * @genpd: PM domain object to initialize.
> @@ -1635,8 +1722,7 @@ void pm_genpd_init(struct generic_pm_domain *genpd,
>  	INIT_LIST_HEAD(&genpd->master_links);
>  	INIT_LIST_HEAD(&genpd->slave_links);
>  	INIT_LIST_HEAD(&genpd->dev_list);
> -	mutex_init(&genpd->mlock);
> -	genpd->lock_fns = &genpd_mtx_fns;
> +	genpd_lock_init(genpd);
>  	genpd->gov = gov;
>  	INIT_WORK(&genpd->power_off_work, genpd_power_off_work_fn);
>  	atomic_set(&genpd->sd_count, 0);
> @@ -2077,7 +2163,8 @@ static int pm_genpd_summary_one(struct seq_file *s,
>  	}
>  
>  	list_for_each_entry(pm_data, &genpd->dev_list, list_node) {
> -		kobj_path = kobject_get_path(&pm_data->dev->kobj, GFP_KERNEL);
> +		kobj_path = kobject_get_path(&pm_data->dev->kobj,
> +				genpd->irq_safe ? GFP_ATOMIC : GFP_KERNEL);

hmm, really? the debugfs stuff is called from atomic context?

Oh, because these same functions currently use the genpd->lock mutex.
Shrug.  OK.

>  		if (kobj_path == NULL)
>  			continue;
>  
> diff --git a/include/linux/pm_domain.h b/include/linux/pm_domain.h
> index 6bebc56..0091282 100644
> --- a/include/linux/pm_domain.h
> +++ b/include/linux/pm_domain.h
> @@ -15,9 +15,11 @@
>  #include <linux/err.h>
>  #include <linux/of.h>
>  #include <linux/notifier.h>
> +#include <linux/spinlock.h>
>  
>  /* Defines used for the flags field in the struct generic_pm_domain */
>  #define GENPD_FLAG_PM_CLK	(1U << 0) /* PM domain uses PM clk */
> +#define GENPD_FLAG_IRQ_SAFE	(1U << 1) /* PM domain operates in atomic */
>  
>  enum gpd_status {
>  	GPD_STATE_ACTIVE = 0,	/* PM domain is active */
> @@ -76,7 +78,14 @@ struct generic_pm_domain {
>  	unsigned int state_count; /* number of states */
>  	unsigned int state_idx; /* state that genpd will go to when off */
>  	const struct genpd_lock_fns *lock_fns;
> -	struct mutex mlock;
> +	bool irq_safe;
> +	union {
> +		struct mutex mlock;
> +		struct {
> +			spinlock_t slock;
> +			unsigned long lock_flags;
> +		};
> +	};
>  
>  };

Kevin

[RFC v3 02/12] PM / Domains: Support IRQ safe PM domains

[Kevin Hilman]

Lina Iyer <lina.iyer@linaro.org> writes:

> Generic Power Domains currently support turning on/off only in process
> context. This prevents the usage of PM domains for domains that could be
> powered on/off in a context where IRQs are disabled. Many such domains
> exist today and do not get powered off, when the IRQ safe devices in
> that domain are powered off, because of this limitation.
>
> However, not all domains can operate in IRQ safe contexts. Genpd
> therefore, has to support both cases where the domain may or may not
> operate in IRQ safe contexts. Configuring genpd to use an appropriate
> lock for that domain, would allow domains that have IRQ safe devices to
> runtime suspend and resume, in atomic context.
>
> To achieve domain specific locking, set the domain's ->flag to
> GENPD_FLAG_IRQ_SAFE while defining the domain. This indicates that genpd
> should use a spinlock instead of a mutex for locking the domain. Locking
> is abstracted through genpd_lock() and genpd_unlock() functions that use
> the flag to determine the appropriate lock to be used for that domain.
>
> Domains that have lower latency to suspend and resume and can operate
> with IRQs disabled may now be able to save power, when the component
> devices and sub-domains are idle at runtime.
>
> The restriction this imposes on the domain hierarchy is that non-IRQ
> safe domains may not have IRQ-safe subdomains, but IRQ safe domains may
> have IRQ safe and non-IRQ safe domains and devices.

I'm starting to think we also need a patch to the debugfg
pm_genpd_summary that will show which domains and which devices are IRQ
safe.

> Cc: Ulf Hansson <ulf.hansson@linaro.org>
> Cc: Kevin Hilman <khilman@linaro.org>
> Cc: Rafael J. Wysocki <rjw@rjwysocki.net>
> Cc: Geert Uytterhoeven <geert@linux-m68k.org>
> Cc: Krzysztof Koz?owski <k.kozlowski@samsung.com>
> Signed-off-by: Lina Iyer <lina.iyer@linaro.org>
> ---
>  Documentation/power/devices.txt |  12 ++++-
>  drivers/base/power/domain.c     | 105 ++++++++++++++++++++++++++++++++++++----
>  include/linux/pm_domain.h       |  11 ++++-
>  3 files changed, 117 insertions(+), 11 deletions(-)
>
> diff --git a/Documentation/power/devices.txt b/Documentation/power/devices.txt
> index 8ba6625..a622136 100644
> --- a/Documentation/power/devices.txt
> +++ b/Documentation/power/devices.txt
> @@ -607,7 +607,17 @@ individually.  Instead, a set of devices sharing a power resource can be put
>  into a low-power state together at the same time by turning off the shared
>  power resource.  Of course, they also need to be put into the full-power state
>  together, by turning the shared power resource on.  A set of devices with this
> -property is often referred to as a power domain.
> +property is often referred to as a power domain. A power domain may also be
> +nested inside another power domain.
> +
> +Devices, by default, operate in process context. If a device can operate in

Not device(s), but runtime PM callbacks for devices are what happen in
process context by default.

> +IRQ safe context that has to be explicitly indicated by setting the irq_safe
> +boolean inside struct generic_pm_domain to be true.

Maybe reference pm_runtime.txt documentation where this is described in
more detail.

> Power domains by default,
> +operate in process context but could have devices that are IRQ safe. Such
> +power domains cannot be powered on/off during runtime PM.

because...  ?

> On the other hand,
> +IRQ safe PM domains that have IRQ safe devices may be powered off when all
> +the devices are in idle. An IRQ safe domain may only be attached as a
> +subdomain to another IRQ safe domain.

The documentation should describe these limitations more, and the
reasons.

Also, this whole new paragraph you added should probably be the last
paragraph in this section, rather than between these two.

Maybe add a sub-section about IRQ safe domains and their limitations.

>  Support for power domains is provided through the pm_domain field of struct
>  device.  This field is a pointer to an object of type struct dev_pm_domain,
> diff --git a/drivers/base/power/domain.c b/drivers/base/power/domain.c
> index 20533d9..9541d80 100644
> --- a/drivers/base/power/domain.c
> +++ b/drivers/base/power/domain.c
> @@ -75,11 +75,59 @@ static const struct genpd_lock_fns genpd_mtx_fns  = {
>  	.unlock = genpd_unlock_mtx,
>  };
>  
> +static void genpd_lock_spin(struct generic_pm_domain *genpd)
> +	__acquires(&genpd->slock)
> +{
> +	unsigned long flags;
> +
> +	spin_lock_irqsave(&genpd->slock, flags);
> +	genpd->lock_flags = flags;
> +}
> +
> +static void genpd_lock_nested_spin(struct generic_pm_domain *genpd,
> +					int depth)
> +	__acquires(&genpd->slock)
> +{
> +	unsigned long flags;
> +
> +	spin_lock_irqsave_nested(&genpd->slock, flags, depth);
> +	genpd->lock_flags = flags;
> +}
> +
> +static int genpd_lock_interruptible_spin(struct generic_pm_domain *genpd)
> +	__acquires(&genpd->slock)
> +{
> +	unsigned long flags;
> +
> +	spin_lock_irqsave(&genpd->slock, flags);
> +	genpd->lock_flags = flags;
> +	return 0;
> +}
> +
> +static void genpd_unlock_spin(struct generic_pm_domain *genpd)
> +	__releases(&genpd->slock)
> +{
> +	spin_unlock_irqrestore(&genpd->slock, genpd->lock_flags);
> +}
> +
> +static const struct genpd_lock_fns genpd_spin_fns = {
> +	.lock = genpd_lock_spin,
> +	.lock_nested = genpd_lock_nested_spin,
> +	.lock_interruptible = genpd_lock_interruptible_spin,
> +	.unlock = genpd_unlock_spin,
> +};
> +
>  #define genpd_lock(p)			p->lock_fns->lock(p)
>  #define genpd_lock_nested(p, d)		p->lock_fns->lock_nested(p, d)
>  #define genpd_lock_interruptible(p)	p->lock_fns->lock_interruptible(p)
>  #define genpd_unlock(p)			p->lock_fns->unlock(p)
>  
> +static inline bool irq_safe_dev_in_no_sleep_domain(struct device *dev,
> +		struct generic_pm_domain *genpd)
> +{
> +	return dev->power.irq_safe && !genpd->irq_safe;
> +}
> +
>  /*
>   * Get the generic PM domain for a particular struct device.
>   * This validates the struct device pointer, the PM domain pointer,
> @@ -356,8 +404,17 @@ static int genpd_poweroff(struct generic_pm_domain *genpd, bool is_async)
>  		if (stat > PM_QOS_FLAGS_NONE)
>  			return -EBUSY;
>  
> -		if (!pm_runtime_suspended(pdd->dev) || pdd->dev->power.irq_safe)
> +		/*
> +		 * We do not want to power off the domain if the device is
> +		 * not suspended or an IRQ safe device is part of this
> +		 * non-IRQ safe domain.
> +		 */
> +		if (!pm_runtime_suspended(pdd->dev) ||
> +			irq_safe_dev_in_no_sleep_domain(pdd->dev, genpd))
>  			not_suspended++;
> +		WARN_ONCE(irq_safe_dev_in_no_sleep_domain(pdd->dev, genpd),
> +				"PM domain %s will not be powered off\n",
> +				genpd->name);

This WARN should include why.  "...because it contains IRQ safe
devices." or something similar, so it gives users a hint about what's
going on.

>  	}
>  
>  	if (not_suspended > 1 || (not_suspended == 1 && is_async))
> @@ -473,10 +530,13 @@ static int pm_genpd_runtime_suspend(struct device *dev)
>  	}
>  
>  	/*
> -	 * If power.irq_safe is set, this routine will be run with interrupts
> -	 * off, so it can't use mutexes.
> +	 * If power.irq_safe is set, this routine may be run with
> +	 * IRQ disabled, so suspend only if the power domain is

s/IRQ/IRQs/ (though I'm not sure why you changed from "interrupts off")

> +	 * irq_safe.
>  	 */
> -	if (dev->power.irq_safe)
> +	WARN_ONCE(irq_safe_dev_in_no_sleep_domain(dev, genpd),
> +			"genpd %s will not be powered off\n", genpd->name);

again, add why.

> +	if (irq_safe_dev_in_no_sleep_domain(dev, genpd))
>  		return 0;
>  
>  	genpd_lock(genpd);
> @@ -510,8 +570,11 @@ static int pm_genpd_runtime_resume(struct device *dev)
>  	if (IS_ERR(genpd))
>  		return -EINVAL;
>  
> -	/* If power.irq_safe, the PM domain is never powered off. */
> -	if (dev->power.irq_safe) {
> +	/*
> +	 * As we don't power off a non IRQ safe domain, which holds
> +	 * an IRQ safe device, we don't need to restore power to it.
> +	 */
> +	if (dev->power.irq_safe && !genpd->irq_safe) {
>  		timed = false;
>  		goto out;
>  	}
> @@ -1394,6 +1457,17 @@ int pm_genpd_add_subdomain(struct generic_pm_domain *genpd,
>  	    || genpd == subdomain)
>  		return -EINVAL;
>  
> +	/*
> +	 * If the domain can be powered on/off in an IRQ safe
> +	 * context, ensure that the subdomain can also be
> +	 * powered on/off in that context.
> +	 */
> +	if (!genpd->irq_safe && subdomain->irq_safe) {
> +		WARN("Parent %s of subdomain %s must be IRQ safe\n",
> +				genpd->name, subdomain->name);
> +		return -EINVAL;
> +	}
> +
>  	link = kzalloc(sizeof(*link), GFP_KERNEL);
>  	if (!link)
>  		return -ENOMEM;
> @@ -1610,6 +1684,19 @@ static int of_genpd_device_parse_states(struct device_node *np,
>  	return 0;
>  }
>  
> +static void genpd_lock_init(struct generic_pm_domain *genpd)
> +{
> +	if (genpd->flags & GENPD_FLAG_IRQ_SAFE) {
> +		spin_lock_init(&genpd->slock);
> +		genpd->irq_safe = true;
> +		genpd->lock_fns = &genpd_spin_fns;
> +	} else {
> +		mutex_init(&genpd->mlock);
> +		genpd->irq_safe = false;
> +		genpd->lock_fns = &genpd_mtx_fns;
> +	}
> +}
> +
>  /**
>   * pm_genpd_init - Initialize a generic I/O PM domain object.
>   * @genpd: PM domain object to initialize.
> @@ -1635,8 +1722,7 @@ void pm_genpd_init(struct generic_pm_domain *genpd,
>  	INIT_LIST_HEAD(&genpd->master_links);
>  	INIT_LIST_HEAD(&genpd->slave_links);
>  	INIT_LIST_HEAD(&genpd->dev_list);
> -	mutex_init(&genpd->mlock);
> -	genpd->lock_fns = &genpd_mtx_fns;
> +	genpd_lock_init(genpd);
>  	genpd->gov = gov;
>  	INIT_WORK(&genpd->power_off_work, genpd_power_off_work_fn);
>  	atomic_set(&genpd->sd_count, 0);
> @@ -2077,7 +2163,8 @@ static int pm_genpd_summary_one(struct seq_file *s,
>  	}
>  
>  	list_for_each_entry(pm_data, &genpd->dev_list, list_node) {
> -		kobj_path = kobject_get_path(&pm_data->dev->kobj, GFP_KERNEL);
> +		kobj_path = kobject_get_path(&pm_data->dev->kobj,
> +				genpd->irq_safe ? GFP_ATOMIC : GFP_KERNEL);

hmm, really? the debugfs stuff is called from atomic context?

Oh, because these same functions currently use the genpd->lock mutex.
Shrug.  OK.

>  		if (kobj_path == NULL)
>  			continue;
>  
> diff --git a/include/linux/pm_domain.h b/include/linux/pm_domain.h
> index 6bebc56..0091282 100644
> --- a/include/linux/pm_domain.h
> +++ b/include/linux/pm_domain.h
> @@ -15,9 +15,11 @@
>  #include <linux/err.h>
>  #include <linux/of.h>
>  #include <linux/notifier.h>
> +#include <linux/spinlock.h>
>  
>  /* Defines used for the flags field in the struct generic_pm_domain */
>  #define GENPD_FLAG_PM_CLK	(1U << 0) /* PM domain uses PM clk */
> +#define GENPD_FLAG_IRQ_SAFE	(1U << 1) /* PM domain operates in atomic */
>  
>  enum gpd_status {
>  	GPD_STATE_ACTIVE = 0,	/* PM domain is active */
> @@ -76,7 +78,14 @@ struct generic_pm_domain {
>  	unsigned int state_count; /* number of states */
>  	unsigned int state_idx; /* state that genpd will go to when off */
>  	const struct genpd_lock_fns *lock_fns;
> -	struct mutex mlock;
> +	bool irq_safe;
> +	union {
> +		struct mutex mlock;
> +		struct {
> +			spinlock_t slock;
> +			unsigned long lock_flags;
> +		};
> +	};
>  
>  };

Kevin

Re: [RFC v3 03/12] PM / cpu_domains: Setup PM domains for CPUs/clusters

[Kevin Hilman]

Lina Iyer <lina.iyer@linaro.org> writes:

> Define and add Generic PM domains (genpd) for CPU clusters. Many new

Not sure this is "new". :)

> SoCs group CPUs as clusters. Clusters share common resources like power
> rails, caches, VFP, Coresight etc. When all CPUs in the cluster are
> idle, these shared resources may also be put in their idle state.
>
> CPUs may be associated with their domain providers in DT. The domains in
> turn may be associated with their providers.

Not sure what this sentence means.

> This is clean way to model
> the cluster hierarchy like that of ARM's big.little architecture.

... or any multi-cluster architecture with independent power rails.

> For each CPU in the DT, we identify the domain provider; initialize and
> register the PM domain if isn't already registered and attach all the
> CPU devices to the domain. Usually, when there are multiple clusters of
> CPUs, there is a top level coherency domain that is dependent on these
> individual domains. All domains thus created are marked IRQ safe
> automatically and therefore may be powered down when the CPUs in the
> domain are powered down by cpuidle.

s/by cpuidle/during the idle path/

A bit about why IRQ safe is needed during the idle path would be good also.

> Reading DT, initializing Generic PM domains, attaching CPUs to it

s/it/their/

> domains are common functionalities across ARM SoCs. Provide a common set

s/ARM/many/

> of APIs to setup PM domains for CPU clusters and its parents. The
> platform drivers may just call of_setup_cpu_pd() to do a single step
> setup of CPU domains.
>
> Cc: Ulf Hansson <ulf.hansson@linaro.org>
> Cc: Daniel Lezcano <daniel.lezcano@linaro.org>
> Cc: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
> Suggested-by: Kevin Hilman <khilman@linaro.org>
> Signed-off-by: Lina Iyer <lina.iyer@linaro.org>
> ---
>  drivers/base/power/Makefile      |   1 +
>  drivers/base/power/cpu_domains.c | 267 +++++++++++++++++++++++++++++++++++++++
>  include/linux/cpu_domains.h      |  35 +++++

nit: cpu_pm_domains.[ch] ?

>  3 files changed, 303 insertions(+)
>  create mode 100644 drivers/base/power/cpu_domains.c
>  create mode 100644 include/linux/cpu_domains.h
>

[...]

> +/**
> + * of_init_cpu_pm_domain() - Initialize a CPU PM domain from a device node
> + *
> + * @dn: The domain provider's device node
> + * @ops: The power_on/_off callbacks for the domain
> + *
> + * Returns the generic_pm_domain (genpd) pointer to the domain on success
> + */
> +static struct generic_pm_domain *of_init_cpu_pm_domain(struct device_node *dn,
> +				const struct cpu_pd_ops *ops)
> +{
> +	struct cpu_pm_domain *pd = NULL;
> +	struct generic_pm_domain *genpd = NULL;
> +	int ret = -ENOMEM;
> +
> +	if (!of_device_is_available(dn))
> +		return ERR_PTR(-ENODEV);
> +
> +	genpd = kzalloc(sizeof(*genpd), GFP_KERNEL);
> +	if (!genpd)
> +		goto fail;
> +
> +	genpd->name = kstrndup(dn->full_name, CPU_PD_NAME_MAX, GFP_KERNEL);
> +	if (!genpd->name)
> +		goto fail;
> +
> +	pd = kzalloc(sizeof(*pd), GFP_KERNEL);
> +	if (!pd)
> +		goto fail;
> +
> +	pd->genpd = genpd;
> +	pd->genpd->power_off = cpu_pd_power_off;
> +	pd->genpd->power_on = cpu_pd_power_on;
> +	pd->genpd->flags |= GENPD_FLAG_IRQ_SAFE;

Again, just to be thorough, maybe a comment here describing that CPU PM
domains must be IRQ safe because the callbacks happend during the idle
path when interrupts are disabled.

[...]

I ran out of time for the day here, but will continue looking at the
rest implementation later.  Thought it best to send what I already
reviewed though.

Kevin

[RFC v3 03/12] PM / cpu_domains: Setup PM domains for CPUs/clusters

[Kevin Hilman]

Lina Iyer <lina.iyer@linaro.org> writes:

> Define and add Generic PM domains (genpd) for CPU clusters. Many new

Not sure this is "new". :)

> SoCs group CPUs as clusters. Clusters share common resources like power
> rails, caches, VFP, Coresight etc. When all CPUs in the cluster are
> idle, these shared resources may also be put in their idle state.
>
> CPUs may be associated with their domain providers in DT. The domains in
> turn may be associated with their providers.

Not sure what this sentence means.

> This is clean way to model
> the cluster hierarchy like that of ARM's big.little architecture.

... or any multi-cluster architecture with independent power rails.

> For each CPU in the DT, we identify the domain provider; initialize and
> register the PM domain if isn't already registered and attach all the
> CPU devices to the domain. Usually, when there are multiple clusters of
> CPUs, there is a top level coherency domain that is dependent on these
> individual domains. All domains thus created are marked IRQ safe
> automatically and therefore may be powered down when the CPUs in the
> domain are powered down by cpuidle.

s/by cpuidle/during the idle path/

A bit about why IRQ safe is needed during the idle path would be good also.

> Reading DT, initializing Generic PM domains, attaching CPUs to it

s/it/their/

> domains are common functionalities across ARM SoCs. Provide a common set

s/ARM/many/

> of APIs to setup PM domains for CPU clusters and its parents. The
> platform drivers may just call of_setup_cpu_pd() to do a single step
> setup of CPU domains.
>
> Cc: Ulf Hansson <ulf.hansson@linaro.org>
> Cc: Daniel Lezcano <daniel.lezcano@linaro.org>
> Cc: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
> Suggested-by: Kevin Hilman <khilman@linaro.org>
> Signed-off-by: Lina Iyer <lina.iyer@linaro.org>
> ---
>  drivers/base/power/Makefile      |   1 +
>  drivers/base/power/cpu_domains.c | 267 +++++++++++++++++++++++++++++++++++++++
>  include/linux/cpu_domains.h      |  35 +++++

nit: cpu_pm_domains.[ch] ?

>  3 files changed, 303 insertions(+)
>  create mode 100644 drivers/base/power/cpu_domains.c
>  create mode 100644 include/linux/cpu_domains.h
>

[...]

> +/**
> + * of_init_cpu_pm_domain() - Initialize a CPU PM domain from a device node
> + *
> + * @dn: The domain provider's device node
> + * @ops: The power_on/_off callbacks for the domain
> + *
> + * Returns the generic_pm_domain (genpd) pointer to the domain on success
> + */
> +static struct generic_pm_domain *of_init_cpu_pm_domain(struct device_node *dn,
> +				const struct cpu_pd_ops *ops)
> +{
> +	struct cpu_pm_domain *pd = NULL;
> +	struct generic_pm_domain *genpd = NULL;
> +	int ret = -ENOMEM;
> +
> +	if (!of_device_is_available(dn))
> +		return ERR_PTR(-ENODEV);
> +
> +	genpd = kzalloc(sizeof(*genpd), GFP_KERNEL);
> +	if (!genpd)
> +		goto fail;
> +
> +	genpd->name = kstrndup(dn->full_name, CPU_PD_NAME_MAX, GFP_KERNEL);
> +	if (!genpd->name)
> +		goto fail;
> +
> +	pd = kzalloc(sizeof(*pd), GFP_KERNEL);
> +	if (!pd)
> +		goto fail;
> +
> +	pd->genpd = genpd;
> +	pd->genpd->power_off = cpu_pd_power_off;
> +	pd->genpd->power_on = cpu_pd_power_on;
> +	pd->genpd->flags |= GENPD_FLAG_IRQ_SAFE;

Again, just to be thorough, maybe a comment here describing that CPU PM
domains must be IRQ safe because the callbacks happend during the idle
path when interrupts are disabled.

[...]

I ran out of time for the day here, but will continue looking at the
rest implementation later.  Thought it best to send what I already
reviewed though.

Kevin

Re: [RFC v3 01/12] PM / Domains: Abstract genpd locking

[Ulf Hansson]

On 1 March 2016 at 22:15, Lina Iyer <lina.iyer@linaro.org> wrote:
> Abstract genpd lock/unlock calls, in preparation for domain specific
> locks added in the following patches.
>
> Cc: Ulf Hansson <ulf.hansson@linaro.org>
> Cc: Kevin Hilman <khilman@linaro.org>
> Cc: Rafael J. Wysocki <rjw@rjwysocki.net>
> Cc: Geert Uytterhoeven <geert@linux-m68k.org>
> Cc: Krzysztof Kozłowski <k.kozlowski@samsung.com>
> Signed-off-by: Lina Iyer <lina.iyer@linaro.org>

[...]

> +struct genpd_lock_fns;
> +
>  struct generic_pm_domain {
>         struct dev_pm_domain domain;    /* PM domain operations */
>         struct list_head gpd_list_node; /* Node in the global PM domains list */
>         struct list_head master_links;  /* Links with PM domain as a master */
>         struct list_head slave_links;   /* Links with PM domain as a slave */
>         struct list_head dev_list;      /* List of devices */
> -       struct mutex lock;
>         struct dev_power_governor *gov;
>         struct work_struct power_off_work;
>         const char *name;
> @@ -74,6 +75,8 @@ struct generic_pm_domain {
>         struct genpd_power_state *states;
>         unsigned int state_count; /* number of states */
>         unsigned int state_idx; /* state that genpd will go to when off */
> +       const struct genpd_lock_fns *lock_fns;
> +       struct mutex mlock;

Nitpick: I wouldn't mind if you name this mtx_lock, as it would be a
bit more consistent with the corresponding helper functions.

>
>  };
>
> --
> 2.1.4
>

Otherwise this looks good to me!

Acked-by: Ulf Hansson <ulf.hansson@linaro.org>

One issue I noticed though, this patch isn't based upon Rafael's
latest tree, thus it can't be applied as is. Could you perhaps
re-base?

I suppose that's needed for some of the other patches as well. I think
we should split up the dependency a bit better so we can move forward
with standalone patches.

Kind regards
Uffe

[RFC v3 01/12] PM / Domains: Abstract genpd locking

[Ulf Hansson]

On 1 March 2016 at 22:15, Lina Iyer <lina.iyer@linaro.org> wrote:
> Abstract genpd lock/unlock calls, in preparation for domain specific
> locks added in the following patches.
>
> Cc: Ulf Hansson <ulf.hansson@linaro.org>
> Cc: Kevin Hilman <khilman@linaro.org>
> Cc: Rafael J. Wysocki <rjw@rjwysocki.net>
> Cc: Geert Uytterhoeven <geert@linux-m68k.org>
> Cc: Krzysztof Koz?owski <k.kozlowski@samsung.com>
> Signed-off-by: Lina Iyer <lina.iyer@linaro.org>

[...]

> +struct genpd_lock_fns;
> +
>  struct generic_pm_domain {
>         struct dev_pm_domain domain;    /* PM domain operations */
>         struct list_head gpd_list_node; /* Node in the global PM domains list */
>         struct list_head master_links;  /* Links with PM domain as a master */
>         struct list_head slave_links;   /* Links with PM domain as a slave */
>         struct list_head dev_list;      /* List of devices */
> -       struct mutex lock;
>         struct dev_power_governor *gov;
>         struct work_struct power_off_work;
>         const char *name;
> @@ -74,6 +75,8 @@ struct generic_pm_domain {
>         struct genpd_power_state *states;
>         unsigned int state_count; /* number of states */
>         unsigned int state_idx; /* state that genpd will go to when off */
> +       const struct genpd_lock_fns *lock_fns;
> +       struct mutex mlock;

Nitpick: I wouldn't mind if you name this mtx_lock, as it would be a
bit more consistent with the corresponding helper functions.

>
>  };
>
> --
> 2.1.4
>

Otherwise this looks good to me!

Acked-by: Ulf Hansson <ulf.hansson@linaro.org>

One issue I noticed though, this patch isn't based upon Rafael's
latest tree, thus it can't be applied as is. Could you perhaps
re-base?

I suppose that's needed for some of the other patches as well. I think
we should split up the dependency a bit better so we can move forward
with standalone patches.

Kind regards
Uffe

Re: [RFC v3 04/12] ARM: cpuidle: Add runtime PM support for CPUs

[Stephen Boyd]

On 03/01, Lina Iyer wrote:
> @@ -46,12 +49,20 @@ static int arm_enter_idle_state(struct cpuidle_device *dev,
>  	ret = cpu_pm_enter();
>  	if (!ret) {
>  		/*
> +		 * Call runtime PM suspend on our device
> +		 * Notify RCU to pay attention to critical sections
> +		 * called from within runtime PM.
> +		 */

I was thinking something more along the lines of 

		/*
		 * RCU is idle at this point but runtime PM uses
		 * tracepoints which use RCU so we must resume RCU
		 * while we use runtime PM here.
		 */

> +		RCU_NONIDLE(pm_runtime_put_sync_suspend(cpu_dev));
> +

-- 
Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum,
a Linux Foundation Collaborative Project

[RFC v3 04/12] ARM: cpuidle: Add runtime PM support for CPUs

[Stephen Boyd]

On 03/01, Lina Iyer wrote:
> @@ -46,12 +49,20 @@ static int arm_enter_idle_state(struct cpuidle_device *dev,
>  	ret = cpu_pm_enter();
>  	if (!ret) {
>  		/*
> +		 * Call runtime PM suspend on our device
> +		 * Notify RCU to pay attention to critical sections
> +		 * called from within runtime PM.
> +		 */

I was thinking something more along the lines of 

		/*
		 * RCU is idle at this point but runtime PM uses
		 * tracepoints which use RCU so we must resume RCU
		 * while we use runtime PM here.
		 */

> +		RCU_NONIDLE(pm_runtime_put_sync_suspend(cpu_dev));
> +

-- 
Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum,
a Linux Foundation Collaborative Project

Re: [RFC v3 11/12] ARM64: dts: Add PSCI cpuidle support for MSM8916

[Andy Gross]

On Tue, Mar 01, 2016 at 02:15:30PM -0700, Lina Iyer wrote:
> Add device bindings for CPUs to suspend using PSCI as the enable-method.
> 
> Cc: <devicetree@vger.kernel.org>
> Signed-off-by: Lina Iyer <lina.iyer@linaro.org>

Works great.  All CPUs functional and I saw SPC idle states incrementing.

Tested-by: Andy Gross <andy.gross@linaro.org>

[RFC v3 11/12] ARM64: dts: Add PSCI cpuidle support for MSM8916

[Andy Gross]

On Tue, Mar 01, 2016 at 02:15:30PM -0700, Lina Iyer wrote:
> Add device bindings for CPUs to suspend using PSCI as the enable-method.
> 
> Cc: <devicetree@vger.kernel.org>
> Signed-off-by: Lina Iyer <lina.iyer@linaro.org>

Works great.  All CPUs functional and I saw SPC idle states incrementing.

Tested-by: Andy Gross <andy.gross@linaro.org>