[PATCH v5 3/3] PM/runtime:Replace jiffies based accounting with ktime based accounting

[Vincent Guittot]

From: Thara Gopinath <thara.gopinath at linaro.org>

This patch replaces jiffies based accounting for runtime_active_time
and runtime_suspended_time with ktime base accounting. This makes the
runtime debug counters inline with genpd and other pm subsytems which
uses ktime based accounting.

timekeeping is initialized before pm_runtime_init() so ktime_get() will
be ready before first call. In fact, timekeeping_init() is called early
in start_kernel() which is way before driver_init() (and that's when
devices can start to be initialized) called from rest_init() via
kernel_init_freeable() and do_basic_setup().

Signed-off-by: Thara Gopinath <thara.gopinath at linaro.org>
[move from ktime to raw nsec]
Signed-off-by: Vincent Guittot <vincent.guittot at linaro.org>
---
 drivers/base/power/runtime.c | 17 +++++++++--------
 drivers/base/power/sysfs.c   | 11 ++++++++---
 include/linux/pm.h           |  6 +++---
 3 files changed, 20 insertions(+), 14 deletions(-)

diff --git a/drivers/base/power/runtime.c b/drivers/base/power/runtime.c
index e695544..f700524 100644
--- a/drivers/base/power/runtime.c
+++ b/drivers/base/power/runtime.c
@@ -64,8 +64,8 @@ static int rpm_suspend(struct device *dev, int rpmflags);
  */
 void update_pm_runtime_accounting(struct device *dev)
 {
-	unsigned long now = jiffies;
-	unsigned long delta;
+	u64 now = ktime_to_ns(ktime_get());
+	u64 delta;
 
 	delta = now - dev->power.accounting_timestamp;
 
@@ -75,9 +75,9 @@ void update_pm_runtime_accounting(struct device *dev)
 		return;
 
 	if (dev->power.runtime_status == RPM_SUSPENDED)
-		dev->power.suspended_jiffies += delta;
+		dev->power.suspended_time += delta;
 	else
-		dev->power.active_jiffies += delta;
+		dev->power.active_time += delta;
 }
 
 static void __update_runtime_status(struct device *dev, enum rpm_status status)
@@ -88,17 +88,18 @@ static void __update_runtime_status(struct device *dev, enum rpm_status status)
 
 u64 pm_runtime_suspended_time(struct device *dev)
 {
-	unsigned long flags, time;
+	u64 time;
+	unsigned long flags;
 
 	spin_lock_irqsave(&dev->power.lock, flags);
 
 	update_pm_runtime_accounting(dev);
 
-	time = dev->power.suspended_jiffies;
+	time = dev->power.suspended_time;
 
 	spin_unlock_irqrestore(&dev->power.lock, flags);
 
-	return jiffies_to_nsecs(time);
+	return time;
 }
 EXPORT_SYMBOL_GPL(pm_runtime_suspended_time);
 
@@ -1503,7 +1504,7 @@ void pm_runtime_init(struct device *dev)
 	dev->power.request_pending = false;
 	dev->power.request = RPM_REQ_NONE;
 	dev->power.deferred_resume = false;
-	dev->power.accounting_timestamp = jiffies;
+	dev->power.accounting_timestamp = ktime_to_ns(ktime_get());
 	INIT_WORK(&dev->power.work, pm_runtime_work);
 
 	dev->power.timer_expires = 0;
diff --git a/drivers/base/power/sysfs.c b/drivers/base/power/sysfs.c
index d713738..96c8a22 100644
--- a/drivers/base/power/sysfs.c
+++ b/drivers/base/power/sysfs.c
@@ -125,9 +125,12 @@ static ssize_t runtime_active_time_show(struct device *dev,
 				struct device_attribute *attr, char *buf)
 {
 	int ret;
+	u64 tmp;
 	spin_lock_irq(&dev->power.lock);
 	update_pm_runtime_accounting(dev);
-	ret = sprintf(buf, "%i\n", jiffies_to_msecs(dev->power.active_jiffies));
+	tmp = dev->power.active_time;
+	do_div(tmp, NSEC_PER_MSEC);
+	ret = sprintf(buf, "%llu\n", tmp);
 	spin_unlock_irq(&dev->power.lock);
 	return ret;
 }
@@ -138,10 +141,12 @@ static ssize_t runtime_suspended_time_show(struct device *dev,
 				struct device_attribute *attr, char *buf)
 {
 	int ret;
+	u64 tmp;
 	spin_lock_irq(&dev->power.lock);
 	update_pm_runtime_accounting(dev);
-	ret = sprintf(buf, "%i\n",
-		jiffies_to_msecs(dev->power.suspended_jiffies));
+	tmp = dev->power.suspended_time;
+	do_div(tmp, NSEC_PER_MSEC);
+	ret = sprintf(buf, "%llu\n", tmp);
 	spin_unlock_irq(&dev->power.lock);
 	return ret;
 }
diff --git a/include/linux/pm.h b/include/linux/pm.h
index e723b78..e5a34e2 100644
--- a/include/linux/pm.h
+++ b/include/linux/pm.h
@@ -632,9 +632,9 @@ struct dev_pm_info {
 	int			runtime_error;
 	int			autosuspend_delay;
 	unsigned long		last_busy;
-	unsigned long		active_jiffies;
-	unsigned long		suspended_jiffies;
-	unsigned long		accounting_timestamp;
+	u64			active_time;
+	u64			suspended_time;
+	u64			accounting_timestamp;
 #endif
 	struct pm_subsys_data	*subsys_data;  /* Owned by the subsystem. */
 	void (*set_latency_tolerance)(struct device *, s32);
-- 
2.7.4