[PATCH] Save/restore periodic tick information over suspend/resume

The programming of periodic tick devices needs to be saved/restored
across suspend/resume - otherwise we might end up with a system coming
up that relies on getting a PIT (or HPET) interrupt, while those devices
default to 'no interrupts' after powerup. (To confuse things it worked
to a certain degree on some systems because the lapic gets initialized
as a side-effect of SMP bootup.)

This suspend / resume thing was dropped unintentionally during the
last-minute -mm code reshuffling.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 32 insertions, 0 deletions

diff --git a/kernel/time/tick-common.c b/kernel/time/tick-common.c
index 0986a2bfab49..43ba1bdec14c 100644
--- a/kernel/time/tick-common.c
+++ b/kernel/time/tick-common.c
@@ -298,6 +298,28 @@ static void tick_shutdown(unsigned int *cpup)
 	spin_unlock_irqrestore(&tick_device_lock, flags);
 }
 
+static void tick_suspend_periodic(void)
+{
+	struct tick_device *td = &__get_cpu_var(tick_cpu_device);
+	unsigned long flags;
+
+	spin_lock_irqsave(&tick_device_lock, flags);
+	if (td->mode == TICKDEV_MODE_PERIODIC)
+		clockevents_set_mode(td->evtdev, CLOCK_EVT_MODE_SHUTDOWN);
+	spin_unlock_irqrestore(&tick_device_lock, flags);
+}
+
+static void tick_resume_periodic(void)
+{
+	struct tick_device *td = &__get_cpu_var(tick_cpu_device);
+	unsigned long flags;
+
+	spin_lock_irqsave(&tick_device_lock, flags);
+	if (td->mode == TICKDEV_MODE_PERIODIC)
+		tick_setup_periodic(td->evtdev, 0);
+	spin_unlock_irqrestore(&tick_device_lock, flags);
+}
+
 /*
  * Notification about clock event devices
  */
@@ -325,6 +347,16 @@ static int tick_notify(struct notifier_block *nb, unsigned long reason,
 		tick_shutdown(dev);
 		break;
 
+	case CLOCK_EVT_NOTIFY_SUSPEND:
+		tick_suspend_periodic();
+		tick_suspend_broadcast();
+		break;
+
+	case CLOCK_EVT_NOTIFY_RESUME:
+		if (!tick_resume_broadcast())
+			tick_resume_periodic();
+		break;
+
 	default:
 		break;
 	}