[PATCH v4] power: new trace event to print device suspend and resume time

[Shuah Khan <shuah.kh@samsung.com>]

A new trace event is added to pm events to print time it takes to suspend and
resume a device. It generates trace message that includes device, driver,
parent information in addition to the type of pm ops invoked as well as the
pm event and error status from the pm ops. Example trace below:

bash-2239  [000] ....   290.883035: device_pm_report_time: backlight
 acpi_video0 parent=0000:00:02.0 state=freeze ops=class nsecs=332 err=0
bash-2239  [000] ....   290.883041: device_pm_report_time: rfkill rf
kill3 parent=phy0 state=freeze ops=legacy class nsecs=216 err=0
bash-2239  [001] ....   290.973892: device_pm_report_time: ieee80211
 phy0 parent=0000:01:00.0 state=freeze ops=legacy class nsecs=90846477 err=0

bash-2239  [001] ....   293.660129: device_pm_report_time: ieee80211 phy0 parent=0000:01:00.0 state=restore ops=legacy class nsecs=101295162 err=0
bash-2239  [001] ....   293.660147: device_pm_report_time: rfkill rfkill3 parent=phy0 state=restore ops=legacy class nsecs=1804 err=0
bash-2239  [001] ....   293.660157: device_pm_report_time: backlight acpi_video0 parent=0000:00:02.0 state=restore ops=class nsecs=757 err=0

Signed-off-by: Shuah Khan <shuah.kh@samsung.com>
---
 drivers/base/power/main.c    |   33 +++++++++++++++++++++++----------
 include/trace/events/power.h |   35 +++++++++++++++++++++++++++++++++++
 2 files changed, 58 insertions(+), 10 deletions(-)

diff --git a/drivers/base/power/main.c b/drivers/base/power/main.c
index 5a9b656..e7401c6 100644
--- a/drivers/base/power/main.c
+++ b/drivers/base/power/main.c
@@ -28,6 +28,7 @@
 #include <linux/sched.h>
 #include <linux/async.h>
 #include <linux/suspend.h>
+#include <trace/events/power.h>
 #include <linux/cpuidle.h>
 #include "../base.h"
 #include "power.h"
@@ -56,6 +57,8 @@ static pm_message_t pm_transition;
 
 static int async_error;
 
+static char *pm_verb(int);
+
 /**
  * device_pm_sleep_init - Initialize system suspend-related device fields.
  * @dev: Device object being initialized.
@@ -172,16 +175,23 @@ static ktime_t initcall_debug_start(struct device *dev)
 }
 
 static void initcall_debug_report(struct device *dev, ktime_t calltime,
-				  int error)
+				  int error, pm_message_t state, char *info)
 {
-	ktime_t delta, rettime;
+	ktime_t rettime;
+	s64 nsecs;
+
+	rettime = ktime_get();
+	nsecs = (s64) ktime_to_ns(ktime_sub(rettime, calltime));
 
 	if (pm_print_times_enabled) {
-		rettime = ktime_get();
-		delta = ktime_sub(rettime, calltime);
 		pr_info("call %s+ returned %d after %Ld usecs\n", dev_name(dev),
-			error, (unsigned long long)ktime_to_ns(delta) >> 10);
+			error, (unsigned long long)nsecs >> 10);
 	}
+
+	trace_device_pm_report_time(dev_name(dev), dev_driver_string(dev),
+				dev->parent ? dev_name(dev->parent) : "none",
+				info ? info : "none ",
+				nsecs, pm_verb(state.event), error);
 }
 
 /**
@@ -379,7 +389,7 @@ static int dpm_run_callback(pm_callback_t cb, struct device *dev,
 	error = cb(dev);
 	suspend_report_result(cb, error);
 
-	initcall_debug_report(dev, calltime, error);
+	initcall_debug_report(dev, calltime, error, state, info);
 
 	return error;
 }
@@ -1027,7 +1037,8 @@ EXPORT_SYMBOL_GPL(dpm_suspend_end);
  * @cb: Suspend callback to execute.
  */
 static int legacy_suspend(struct device *dev, pm_message_t state,
-			  int (*cb)(struct device *dev, pm_message_t state))
+			  int (*cb)(struct device *dev, pm_message_t state),
+			  char *info)
 {
 	int error;
 	ktime_t calltime;
@@ -1037,7 +1048,7 @@ static int legacy_suspend(struct device *dev, pm_message_t state,
 	error = cb(dev, state);
 	suspend_report_result(cb, error);
 
-	initcall_debug_report(dev, calltime, error);
+	initcall_debug_report(dev, calltime, error, state, info);
 
 	return error;
 }
@@ -1097,7 +1108,8 @@ static int __device_suspend(struct device *dev, pm_message_t state, bool async)
 			goto Run;
 		} else if (dev->class->suspend) {
 			pm_dev_dbg(dev, state, "legacy class ");
-			error = legacy_suspend(dev, state, dev->class->suspend);
+			error = legacy_suspend(dev, state, dev->class->suspend,
+						"legacy class ");
 			goto End;
 		}
 	}
@@ -1108,7 +1120,8 @@ static int __device_suspend(struct device *dev, pm_message_t state, bool async)
 			callback = pm_op(dev->bus->pm, state);
 		} else if (dev->bus->suspend) {
 			pm_dev_dbg(dev, state, "legacy bus ");
-			error = legacy_suspend(dev, state, dev->bus->suspend);
+			error = legacy_suspend(dev, state, dev->bus->suspend,
+						"legacy bus ");
 			goto End;
 		}
 	}
diff --git a/include/trace/events/power.h b/include/trace/events/power.h
index 8e42410..24afd22 100644
--- a/include/trace/events/power.h
+++ b/include/trace/events/power.h
@@ -66,6 +66,41 @@ TRACE_EVENT(machine_suspend,
 	TP_printk("state=%lu", (unsigned long)__entry->state)
 );
 
+TRACE_EVENT(device_pm_report_time,
+
+	TP_PROTO(const char *device, const char *driver, const char *parent,
+		 const char *pm_ops, s64 ops_time, char *pm_event_str,
+		 int error),
+
+	TP_ARGS(device, driver, parent, pm_ops, ops_time, pm_event_str, error),
+
+	TP_STRUCT__entry(
+		__string(device, device)
+		__string(driver, driver)
+		__string(parent, parent)
+		__string(pm_ops, pm_ops)
+		__string(pm_event_str, pm_event_str)
+		__field(s64, ops_time)
+		__field(int, error)
+	),
+
+	TP_fast_assign(
+		__assign_str(device, device);
+		__assign_str(driver, driver);
+		__assign_str(parent, parent);
+		__assign_str(pm_ops, pm_ops);
+		__assign_str(pm_event_str, pm_event_str);
+		__entry->ops_time = ops_time;
+		__entry->error = error;
+	),
+
+	/* ops_str has an extra space at the end */
+	TP_printk("%s %s parent=%s state=%s ops=%snsecs=%lld err=%d",
+		__get_str(driver), __get_str(device), __get_str(parent),
+		__get_str(pm_event_str), __get_str(pm_ops),
+		__entry->ops_time, __entry->error)
+);
+
 DECLARE_EVENT_CLASS(wakeup_source,
 
 	TP_PROTO(const char *name, unsigned int state),
-- 
1.7.10.4