timekeeping: Add suspend and resume of clock event devices

Some clock event devices, for example such that belong to PM domains,
need to be handled in a spcial way during the timekeeping suspend
and resume (which takes place in the system core, or "syscore",
stages of system power transitions) in analogy with clock sources.

Introduce .suspend() and .resume() callbacks for clock event devices
that will be executed by timekeeping_suspend/_resume(), respectively,
next the the clock sources' .suspend() and .resume() callbacks.

Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>

2 files changed, 26 insertions, 0 deletions

diff --git a/kernel/time/clockevents.c b/kernel/time/clockevents.c
index 7e1ce01..30b6de0 100644
--- a/kernel/time/clockevents.c
+++ b/kernel/time/clockevents.c
@@ -397,6 +397,30 @@ void clockevents_exchange_device(struct clock_event_device *old,
 	local_irq_restore(flags);
 }
 
+/**
+ * clockevents_suspend - suspend clock devices
+ */
+void clockevents_suspend(void)
+{
+	struct clock_event_device *dev;
+
+	list_for_each_entry_reverse(dev, &clockevent_devices, list)
+		if (dev->suspend)
+			dev->suspend(dev);
+}
+
+/**
+ * clockevents_resume - resume clock devices
+ */
+void clockevents_resume(void)
+{
+	struct clock_event_device *dev;
+
+	list_for_each_entry(dev, &clockevent_devices, list)
+		if (dev->resume)
+			dev->resume(dev);
+}
+
 #ifdef CONFIG_GENERIC_CLOCKEVENTS
 /**
  * clockevents_notify - notification about relevant events
diff --git a/kernel/time/timekeeping.c b/kernel/time/timekeeping.c
index 34e5eac..312a675 100644
--- a/kernel/time/timekeeping.c
+++ b/kernel/time/timekeeping.c
@@ -773,6 +773,7 @@ static void timekeeping_resume(void)
 
 	read_persistent_clock(&ts);
 
+	clockevents_resume();
 	clocksource_resume();
 
 	write_seqlock_irqsave(&tk->lock, flags);
@@ -832,6 +833,7 @@ static int timekeeping_suspend(void)
 
 	clockevents_notify(CLOCK_EVT_NOTIFY_SUSPEND, NULL);
 	clocksource_suspend();
+	clockevents_suspend();
 
 	return 0;
 }