[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>

3 files changed, 72 insertions, 0 deletions

diff --git a/kernel/time/tick-broadcast.c b/kernel/time/tick-broadcast.c
index 12b3efeb9f6f..5567745470f7 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;
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;
         }
diff --git a/kernel/time/tick-internal.h b/kernel/time/tick-internal.h
index 54861a0f29ff..75890efd24ff 100644
--- a/kernel/time/tick-internal.h
+++ b/kernel/time/tick-internal.h
@@ -67,6 +67,8 @@ extern int tick_check_broadcast_device(struct clock_event_device *dev);
 extern int tick_is_broadcast_device(struct clock_event_device *dev);
 extern void tick_broadcast_on_off(unsigned long reason, int *oncpu);
 extern void tick_shutdown_broadcast(unsigned int *cpup);
+extern void tick_suspend_broadcast(void);
+extern int tick_resume_broadcast(void);
 
 extern void
 tick_set_periodic_handler(struct clock_event_device *dev, int broadcast);
@@ -90,6 +92,8 @@ static inline int tick_device_uses_broadcast(struct clock_event_device *dev,
 static inline void tick_do_periodic_broadcast(struct clock_event_device *d) { }
 static inline void tick_broadcast_on_off(unsigned long reason, int *oncpu) { }
 static inline void tick_shutdown_broadcast(unsigned int *cpup) { }
+static inline void tick_suspend_broadcast(void) { }
+static inline int tick_resume_broadcast(void) { return 0; }
 
 /*
  * Set the periodic handler in non broadcast mode