[PATCH v3 07/15] ARM: cpuidle: Add runtime PM support for CPUs

Lina Iyer
2016-08-04T23:04:54Z

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 e342565e..3abd145 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.
*/
ret = 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);
}
--
2.7.4