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-rw-r--r--kernel/time/tick-broadcast.c191
1 files changed, 190 insertions, 1 deletions
diff --git a/kernel/time/tick-broadcast.c b/kernel/time/tick-broadcast.c
index 0ee4968ff791..8314ecb32d33 100644
--- a/kernel/time/tick-broadcast.c
+++ b/kernel/time/tick-broadcast.c
@@ -29,7 +29,7 @@
struct tick_device tick_broadcast_device;
static cpumask_t tick_broadcast_mask;
-DEFINE_SPINLOCK(tick_broadcast_lock);
+static DEFINE_SPINLOCK(tick_broadcast_lock);
/*
* Start the device in periodic mode
@@ -215,6 +215,8 @@ static void tick_do_broadcast_on_off(void *why)
else {
if (tick_broadcast_device.mode == TICKDEV_MODE_PERIODIC)
tick_broadcast_start_periodic(bc);
+ else
+ tick_broadcast_setup_oneshot(bc);
}
out:
spin_unlock_irqrestore(&tick_broadcast_lock, flags);
@@ -268,3 +270,190 @@ void tick_shutdown_broadcast(unsigned int *cpup)
spin_unlock_irqrestore(&tick_broadcast_lock, flags);
}
+
+#ifdef CONFIG_TICK_ONESHOT
+
+static cpumask_t tick_broadcast_oneshot_mask;
+
+static int tick_broadcast_set_event(ktime_t expires, int force)
+{
+ struct clock_event_device *bc = tick_broadcast_device.evtdev;
+ ktime_t now = ktime_get();
+ int res;
+
+ for(;;) {
+ res = clockevents_program_event(bc, expires, now);
+ if (!res || !force)
+ return res;
+ now = ktime_get();
+ expires = ktime_add(now, ktime_set(0, bc->min_delta_ns));
+ }
+}
+
+/*
+ * Reprogram the broadcast device:
+ *
+ * Called with tick_broadcast_lock held and interrupts disabled.
+ */
+static int tick_broadcast_reprogram(void)
+{
+ ktime_t expires = { .tv64 = KTIME_MAX };
+ struct tick_device *td;
+ int cpu;
+
+ /*
+ * Find the event which expires next:
+ */
+ for (cpu = first_cpu(tick_broadcast_oneshot_mask); cpu != NR_CPUS;
+ cpu = next_cpu(cpu, tick_broadcast_oneshot_mask)) {
+ td = &per_cpu(tick_cpu_device, cpu);
+ if (td->evtdev->next_event.tv64 < expires.tv64)
+ expires = td->evtdev->next_event;
+ }
+
+ if (expires.tv64 == KTIME_MAX)
+ return 0;
+
+ return tick_broadcast_set_event(expires, 0);
+}
+
+/*
+ * Handle oneshot mode broadcasting
+ */
+static void tick_handle_oneshot_broadcast(struct clock_event_device *dev)
+{
+ struct tick_device *td;
+ cpumask_t mask;
+ ktime_t now;
+ int cpu;
+
+ spin_lock(&tick_broadcast_lock);
+again:
+ dev->next_event.tv64 = KTIME_MAX;
+ mask = CPU_MASK_NONE;
+ now = ktime_get();
+ /* Find all expired events */
+ for (cpu = first_cpu(tick_broadcast_oneshot_mask); cpu != NR_CPUS;
+ cpu = next_cpu(cpu, tick_broadcast_oneshot_mask)) {
+ td = &per_cpu(tick_cpu_device, cpu);
+ if (td->evtdev->next_event.tv64 <= now.tv64)
+ cpu_set(cpu, mask);
+ }
+
+ /*
+ * Wakeup the cpus which have an expired event. The broadcast
+ * device is reprogrammed in the return from idle code.
+ */
+ if (!tick_do_broadcast(mask)) {
+ /*
+ * The global event did not expire any CPU local
+ * events. This happens in dyntick mode, as the
+ * maximum PIT delta is quite small.
+ */
+ if (tick_broadcast_reprogram())
+ goto again;
+ }
+ spin_unlock(&tick_broadcast_lock);
+}
+
+/*
+ * Powerstate information: The system enters/leaves a state, where
+ * affected devices might stop
+ */
+void tick_broadcast_oneshot_control(unsigned long reason)
+{
+ struct clock_event_device *bc, *dev;
+ struct tick_device *td;
+ unsigned long flags;
+ int cpu;
+
+ spin_lock_irqsave(&tick_broadcast_lock, flags);
+
+ /*
+ * Periodic mode does not care about the enter/exit of power
+ * states
+ */
+ if (tick_broadcast_device.mode == TICKDEV_MODE_PERIODIC)
+ goto out;
+
+ bc = tick_broadcast_device.evtdev;
+ cpu = smp_processor_id();
+ td = &per_cpu(tick_cpu_device, cpu);
+ dev = td->evtdev;
+
+ if (!(dev->features & CLOCK_EVT_FEAT_C3STOP))
+ goto out;
+
+ if (reason == CLOCK_EVT_NOTIFY_BROADCAST_ENTER) {
+ if (!cpu_isset(cpu, tick_broadcast_oneshot_mask)) {
+ cpu_set(cpu, tick_broadcast_oneshot_mask);
+ clockevents_set_mode(dev, CLOCK_EVT_MODE_SHUTDOWN);
+ if (dev->next_event.tv64 < bc->next_event.tv64)
+ tick_broadcast_set_event(dev->next_event, 1);
+ }
+ } else {
+ if (cpu_isset(cpu, tick_broadcast_oneshot_mask)) {
+ cpu_clear(cpu, tick_broadcast_oneshot_mask);
+ clockevents_set_mode(dev, CLOCK_EVT_MODE_ONESHOT);
+ if (dev->next_event.tv64 != KTIME_MAX)
+ tick_program_event(dev->next_event, 1);
+ }
+ }
+
+out:
+ spin_unlock_irqrestore(&tick_broadcast_lock, flags);
+}
+
+/**
+ * tick_broadcast_setup_highres - setup the broadcast device for highres
+ */
+void tick_broadcast_setup_oneshot(struct clock_event_device *bc)
+{
+ if (bc->mode != CLOCK_EVT_MODE_ONESHOT) {
+ bc->event_handler = tick_handle_oneshot_broadcast;
+ clockevents_set_mode(bc, CLOCK_EVT_MODE_ONESHOT);
+ bc->next_event.tv64 = KTIME_MAX;
+ }
+}
+
+/*
+ * Select oneshot operating mode for the broadcast device
+ */
+void tick_broadcast_switch_to_oneshot(void)
+{
+ struct clock_event_device *bc;
+ unsigned long flags;
+
+ spin_lock_irqsave(&tick_broadcast_lock, flags);
+
+ tick_broadcast_device.mode = TICKDEV_MODE_ONESHOT;
+ bc = tick_broadcast_device.evtdev;
+ if (bc)
+ tick_broadcast_setup_oneshot(bc);
+ spin_unlock_irqrestore(&tick_broadcast_lock, flags);
+}
+
+
+/*
+ * Remove a dead CPU from broadcasting
+ */
+void tick_shutdown_broadcast_oneshot(unsigned int *cpup)
+{
+ struct clock_event_device *bc;
+ unsigned long flags;
+ unsigned int cpu = *cpup;
+
+ spin_lock_irqsave(&tick_broadcast_lock, flags);
+
+ bc = tick_broadcast_device.evtdev;
+ cpu_clear(cpu, tick_broadcast_oneshot_mask);
+
+ if (tick_broadcast_device.mode == TICKDEV_MODE_ONESHOT) {
+ if (bc && cpus_empty(tick_broadcast_oneshot_mask))
+ clockevents_set_mode(bc, CLOCK_EVT_MODE_SHUTDOWN);
+ }
+
+ spin_unlock_irqrestore(&tick_broadcast_lock, flags);
+}
+
+#endif
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