[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, 36 insertions, 0 deletions

diff --git a/kernel/time/tick-broadcast.c b/kernel/time/tick-broadcast.c
index 12b3efeb9f6..5567745470f 100644
--- a/kernel/time/tick-broadcast.c
+++ b/kernel/time/tick-broadcast.c
@@ -284,6 +284,42 @@ void tick_shutdown_broadcast(unsigned int *cpup)
 	spin_unlock_irqrestore(&tick_broadcast_lock, flags);
 }
 
+void tick_suspend_broadcast(void)
+{
+	struct clock_event_device *bc;
+	unsigned long flags;
+
+	spin_lock_irqsave(&tick_broadcast_lock, flags);
+
+	bc = tick_broadcast_device.evtdev;
+	if (bc && tick_broadcast_device.mode == TICKDEV_MODE_PERIODIC)
+		clockevents_set_mode(bc, CLOCK_EVT_MODE_SHUTDOWN);
+
+	spin_unlock_irqrestore(&tick_broadcast_lock, flags);
+}
+
+int tick_resume_broadcast(void)
+{
+	struct clock_event_device *bc;
+	unsigned long flags;
+	int broadcast = 0;
+
+	spin_lock_irqsave(&tick_broadcast_lock, flags);
+
+	bc = tick_broadcast_device.evtdev;
+	if (bc) {
+		if (tick_broadcast_device.mode == TICKDEV_MODE_PERIODIC &&
+		    !cpus_empty(tick_broadcast_mask))
+			tick_broadcast_start_periodic(bc);
+
+		broadcast = cpu_isset(smp_processor_id(), tick_broadcast_mask);
+	}
+	spin_unlock_irqrestore(&tick_broadcast_lock, flags);
+
+	return broadcast;
+}
+
+
 #ifdef CONFIG_TICK_ONESHOT
 
 static cpumask_t tick_broadcast_oneshot_mask;