Power: Report suspend times from last_suspend_time

This node epxorts two values separated by space.
From left to right:
1. time spent in suspend/resume process
2. time spent sleep in suspend state

Change-Id: I2cb9a9408a5fd12166aaec11b935a0fd6a408c63

2 files changed, 52 insertions, 0 deletions

diff --git a/Documentation/ABI/testing/sysfs-kernel-wakeup_reasons b/Documentation/ABI/testing/sysfs-kernel-wakeup_reasons
new file mode 100644
index 000000000000..acb19b91c192
--- /dev/null
+++ b/Documentation/ABI/testing/sysfs-kernel-wakeup_reasons
@@ -0,0 +1,16 @@
+What:		/sys/kernel/wakeup_reasons/last_resume_reason
+Date:		February 2014
+Contact:	Ruchi Kandoi <kandoiruchi@google.com>
+Description:
+		The /sys/kernel/wakeup_reasons/last_resume_reason is
+		used to report wakeup reasons after system exited suspend.
+
+What:		/sys/kernel/wakeup_reasons/last_suspend_time
+Date:		March 2015
+Contact:	jinqian <jinqian@google.com>
+Description:
+		The /sys/kernel/wakeup_reasons/last_suspend_time is
+		used to report time spent in last suspend cycle. It contains
+		two numbers (in seconds) separated by space. First number is
+		the time spent in suspend and resume processes. Second number
+		is the time spent in sleep state.
\ No newline at end of file
diff --git a/kernel/power/wakeup_reason.c b/kernel/power/wakeup_reason.c
index 085c99edca06..76b53400cb16 100644
--- a/kernel/power/wakeup_reason.c
+++ b/kernel/power/wakeup_reason.c
@@ -36,6 +36,11 @@ static char abort_reason[MAX_SUSPEND_ABORT_LEN];
 static struct kobject *wakeup_reason;
 static DEFINE_SPINLOCK(resume_reason_lock);
 
+static struct timespec last_xtime; /* wall time before last suspend */
+static struct timespec curr_xtime; /* wall time after last suspend */
+static struct timespec last_stime; /* total_sleep_time before last suspend */
+static struct timespec curr_stime; /* total_sleep_time after last suspend */
+
 static ssize_t last_resume_reason_show(struct kobject *kobj, struct kobj_attribute *attr,
 		char *buf)
 {
@@ -59,10 +64,32 @@ static ssize_t last_resume_reason_show(struct kobject *kobj, struct kobj_attribu
 	return buf_offset;
 }
 
+static ssize_t last_suspend_time_show(struct kobject *kobj,
+			struct kobj_attribute *attr, char *buf)
+{
+	struct timespec sleep_time;
+	struct timespec total_time;
+	struct timespec suspend_resume_time;
+
+	sleep_time = timespec_sub(curr_stime, last_stime);
+	total_time = timespec_sub(curr_xtime, last_xtime);
+	suspend_resume_time = timespec_sub(total_time, sleep_time);
+
+	/*
+	 * suspend_resume_time is calculated from sleep_time. Userspace would
+	 * always need both. Export them in pair here.
+	 */
+	return sprintf(buf, "%lu.%09lu %lu.%09lu\n",
+				suspend_resume_time.tv_sec, suspend_resume_time.tv_nsec,
+				sleep_time.tv_sec, sleep_time.tv_nsec);
+}
+
 static struct kobj_attribute resume_reason = __ATTR_RO(last_resume_reason);
+static struct kobj_attribute suspend_time = __ATTR_RO(last_suspend_time);
 
 static struct attribute *attrs[] = {
 	&resume_reason.attr,
+	&suspend_time.attr,
 	NULL,
 };
 static struct attribute_group attr_group = {
@@ -133,12 +160,21 @@ void log_suspend_abort_reason(const char *fmt, ...)
 static int wakeup_reason_pm_event(struct notifier_block *notifier,
 		unsigned long pm_event, void *unused)
 {
+	struct timespec xtom; /* wall_to_monotonic, ignored */
+
 	switch (pm_event) {
 	case PM_SUSPEND_PREPARE:
 		spin_lock(&resume_reason_lock);
 		irqcount = 0;
 		suspend_abort = false;
 		spin_unlock(&resume_reason_lock);
+
+		get_xtime_and_monotonic_and_sleep_offset(&last_xtime, &xtom,
+			&last_stime);
+		break;
+	case PM_POST_SUSPEND:
+		get_xtime_and_monotonic_and_sleep_offset(&curr_xtime, &xtom,
+			&curr_stime);
 		break;
 	default:
 		break;