2 * linux/kernel/time/tick-broadcast.c
4 * This file contains functions which emulate a local clock-event
5 * device via a broadcast event source.
7 * Copyright(C) 2005-2006, Thomas Gleixner <tglx@linutronix.de>
8 * Copyright(C) 2005-2007, Red Hat, Inc., Ingo Molnar
9 * Copyright(C) 2006-2007, Timesys Corp., Thomas Gleixner
11 * This code is licenced under the GPL version 2. For details see
12 * kernel-base/COPYING.
14 #include <linux/cpu.h>
15 #include <linux/err.h>
16 #include <linux/hrtimer.h>
17 #include <linux/interrupt.h>
18 #include <linux/percpu.h>
19 #include <linux/profile.h>
20 #include <linux/sched.h>
21 #include <linux/smp.h>
22 #include <linux/module.h>
24 #include "tick-internal.h"
27 * Broadcast support for broken x86 hardware, where the local apic
28 * timer stops in C3 state.
31 static struct tick_device tick_broadcast_device;
32 static cpumask_var_t tick_broadcast_mask;
33 static cpumask_var_t tick_broadcast_on;
34 static cpumask_var_t tmpmask;
35 static DEFINE_RAW_SPINLOCK(tick_broadcast_lock);
36 static int tick_broadcast_forced;
38 #ifdef CONFIG_TICK_ONESHOT
39 static void tick_broadcast_clear_oneshot(int cpu);
40 static void tick_resume_broadcast_oneshot(struct clock_event_device *bc);
42 static inline void tick_broadcast_clear_oneshot(int cpu) { }
43 static inline void tick_resume_broadcast_oneshot(struct clock_event_device *bc) { }
47 * Debugging: see timer_list.c
49 struct tick_device *tick_get_broadcast_device(void)
51 return &tick_broadcast_device;
54 struct cpumask *tick_get_broadcast_mask(void)
56 return tick_broadcast_mask;
60 * Start the device in periodic mode
62 static void tick_broadcast_start_periodic(struct clock_event_device *bc)
65 tick_setup_periodic(bc, 1);
69 * Check, if the device can be utilized as broadcast device:
71 static bool tick_check_broadcast_device(struct clock_event_device *curdev,
72 struct clock_event_device *newdev)
74 if ((newdev->features & CLOCK_EVT_FEAT_DUMMY) ||
75 (newdev->features & CLOCK_EVT_FEAT_PERCPU) ||
76 (newdev->features & CLOCK_EVT_FEAT_C3STOP))
79 if (tick_broadcast_device.mode == TICKDEV_MODE_ONESHOT &&
80 !(newdev->features & CLOCK_EVT_FEAT_ONESHOT))
83 return !curdev || newdev->rating > curdev->rating;
87 * Conditionally install/replace broadcast device
89 void tick_install_broadcast_device(struct clock_event_device *dev)
91 struct clock_event_device *cur = tick_broadcast_device.evtdev;
93 if (!tick_check_broadcast_device(cur, dev))
96 if (!try_module_get(dev->owner))
99 clockevents_exchange_device(cur, dev);
101 cur->event_handler = clockevents_handle_noop;
102 tick_broadcast_device.evtdev = dev;
103 if (!cpumask_empty(tick_broadcast_mask))
104 tick_broadcast_start_periodic(dev);
106 * Inform all cpus about this. We might be in a situation
107 * where we did not switch to oneshot mode because the per cpu
108 * devices are affected by CLOCK_EVT_FEAT_C3STOP and the lack
109 * of a oneshot capable broadcast device. Without that
110 * notification the systems stays stuck in periodic mode
113 if (dev->features & CLOCK_EVT_FEAT_ONESHOT)
118 * Check, if the device is the broadcast device
120 int tick_is_broadcast_device(struct clock_event_device *dev)
122 return (dev && tick_broadcast_device.evtdev == dev);
125 int tick_broadcast_update_freq(struct clock_event_device *dev, u32 freq)
129 if (tick_is_broadcast_device(dev)) {
130 raw_spin_lock(&tick_broadcast_lock);
131 ret = __clockevents_update_freq(dev, freq);
132 raw_spin_unlock(&tick_broadcast_lock);
138 static void err_broadcast(const struct cpumask *mask)
140 pr_crit_once("Failed to broadcast timer tick. Some CPUs may be unresponsive.\n");
143 static void tick_device_setup_broadcast_func(struct clock_event_device *dev)
146 dev->broadcast = tick_broadcast;
147 if (!dev->broadcast) {
148 pr_warn_once("%s depends on broadcast, but no broadcast function available\n",
150 dev->broadcast = err_broadcast;
155 * Check, if the device is disfunctional and a place holder, which
156 * needs to be handled by the broadcast device.
158 int tick_device_uses_broadcast(struct clock_event_device *dev, int cpu)
160 struct clock_event_device *bc = tick_broadcast_device.evtdev;
164 raw_spin_lock_irqsave(&tick_broadcast_lock, flags);
167 * Devices might be registered with both periodic and oneshot
168 * mode disabled. This signals, that the device needs to be
169 * operated from the broadcast device and is a placeholder for
170 * the cpu local device.
172 if (!tick_device_is_functional(dev)) {
173 dev->event_handler = tick_handle_periodic;
174 tick_device_setup_broadcast_func(dev);
175 cpumask_set_cpu(cpu, tick_broadcast_mask);
176 if (tick_broadcast_device.mode == TICKDEV_MODE_PERIODIC)
177 tick_broadcast_start_periodic(bc);
179 tick_broadcast_setup_oneshot(bc);
183 * Clear the broadcast bit for this cpu if the
184 * device is not power state affected.
186 if (!(dev->features & CLOCK_EVT_FEAT_C3STOP))
187 cpumask_clear_cpu(cpu, tick_broadcast_mask);
189 tick_device_setup_broadcast_func(dev);
192 * Clear the broadcast bit if the CPU is not in
193 * periodic broadcast on state.
195 if (!cpumask_test_cpu(cpu, tick_broadcast_on))
196 cpumask_clear_cpu(cpu, tick_broadcast_mask);
198 switch (tick_broadcast_device.mode) {
199 case TICKDEV_MODE_ONESHOT:
201 * If the system is in oneshot mode we can
202 * unconditionally clear the oneshot mask bit,
203 * because the CPU is running and therefore
204 * not in an idle state which causes the power
205 * state affected device to stop. Let the
206 * caller initialize the device.
208 tick_broadcast_clear_oneshot(cpu);
212 case TICKDEV_MODE_PERIODIC:
214 * If the system is in periodic mode, check
215 * whether the broadcast device can be
218 if (cpumask_empty(tick_broadcast_mask) && bc)
219 clockevents_shutdown(bc);
221 * If we kept the cpu in the broadcast mask,
222 * tell the caller to leave the per cpu device
223 * in shutdown state. The periodic interrupt
224 * is delivered by the broadcast device, if
225 * the broadcast device exists and is not
228 if (bc && !(bc->features & CLOCK_EVT_FEAT_HRTIMER))
229 ret = cpumask_test_cpu(cpu, tick_broadcast_mask);
235 raw_spin_unlock_irqrestore(&tick_broadcast_lock, flags);
239 #ifdef CONFIG_GENERIC_CLOCKEVENTS_BROADCAST
240 int tick_receive_broadcast(void)
242 struct tick_device *td = this_cpu_ptr(&tick_cpu_device);
243 struct clock_event_device *evt = td->evtdev;
248 if (!evt->event_handler)
251 evt->event_handler(evt);
257 * Broadcast the event to the cpus, which are set in the mask (mangled).
259 static bool tick_do_broadcast(struct cpumask *mask)
261 int cpu = smp_processor_id();
262 struct tick_device *td;
266 * Check, if the current cpu is in the mask
268 if (cpumask_test_cpu(cpu, mask)) {
269 struct clock_event_device *bc = tick_broadcast_device.evtdev;
271 cpumask_clear_cpu(cpu, mask);
273 * We only run the local handler, if the broadcast
274 * device is not hrtimer based. Otherwise we run into
275 * a hrtimer recursion.
277 * local timer_interrupt()
284 local = !(bc->features & CLOCK_EVT_FEAT_HRTIMER);
287 if (!cpumask_empty(mask)) {
289 * It might be necessary to actually check whether the devices
290 * have different broadcast functions. For now, just use the
291 * one of the first device. This works as long as we have this
292 * misfeature only on x86 (lapic)
294 td = &per_cpu(tick_cpu_device, cpumask_first(mask));
295 td->evtdev->broadcast(mask);
301 * Periodic broadcast:
302 * - invoke the broadcast handlers
304 static bool tick_do_periodic_broadcast(void)
306 cpumask_and(tmpmask, cpu_online_mask, tick_broadcast_mask);
307 return tick_do_broadcast(tmpmask);
311 * Event handler for periodic broadcast ticks
313 static void tick_handle_periodic_broadcast(struct clock_event_device *dev)
315 struct tick_device *td = this_cpu_ptr(&tick_cpu_device);
318 raw_spin_lock(&tick_broadcast_lock);
319 bc_local = tick_do_periodic_broadcast();
321 if (clockevent_state_oneshot(dev)) {
322 ktime_t next = ktime_add(dev->next_event, tick_period);
324 clockevents_program_event(dev, next, true);
326 raw_spin_unlock(&tick_broadcast_lock);
329 * We run the handler of the local cpu after dropping
330 * tick_broadcast_lock because the handler might deadlock when
331 * trying to switch to oneshot mode.
334 td->evtdev->event_handler(td->evtdev);
338 * tick_broadcast_control - Enable/disable or force broadcast mode
339 * @mode: The selected broadcast mode
341 * Called when the system enters a state where affected tick devices
342 * might stop. Note: TICK_BROADCAST_FORCE cannot be undone.
344 * Called with interrupts disabled, so clockevents_lock is not
345 * required here because the local clock event device cannot go away
348 void tick_broadcast_control(enum tick_broadcast_mode mode)
350 struct clock_event_device *bc, *dev;
351 struct tick_device *td;
354 td = this_cpu_ptr(&tick_cpu_device);
358 * Is the device not affected by the powerstate ?
360 if (!dev || !(dev->features & CLOCK_EVT_FEAT_C3STOP))
363 if (!tick_device_is_functional(dev))
366 raw_spin_lock(&tick_broadcast_lock);
367 cpu = smp_processor_id();
368 bc = tick_broadcast_device.evtdev;
369 bc_stopped = cpumask_empty(tick_broadcast_mask);
372 case TICK_BROADCAST_FORCE:
373 tick_broadcast_forced = 1;
374 case TICK_BROADCAST_ON:
375 cpumask_set_cpu(cpu, tick_broadcast_on);
376 if (!cpumask_test_and_set_cpu(cpu, tick_broadcast_mask)) {
378 * Only shutdown the cpu local device, if:
380 * - the broadcast device exists
381 * - the broadcast device is not a hrtimer based one
382 * - the broadcast device is in periodic mode to
383 * avoid a hickup during switch to oneshot mode
385 if (bc && !(bc->features & CLOCK_EVT_FEAT_HRTIMER) &&
386 tick_broadcast_device.mode == TICKDEV_MODE_PERIODIC)
387 clockevents_shutdown(dev);
391 case TICK_BROADCAST_OFF:
392 if (tick_broadcast_forced)
394 cpumask_clear_cpu(cpu, tick_broadcast_on);
395 if (!tick_device_is_functional(dev))
397 if (cpumask_test_and_clear_cpu(cpu, tick_broadcast_mask)) {
398 if (tick_broadcast_device.mode ==
399 TICKDEV_MODE_PERIODIC)
400 tick_setup_periodic(dev, 0);
405 if (cpumask_empty(tick_broadcast_mask)) {
407 clockevents_shutdown(bc);
408 } else if (bc_stopped) {
409 if (tick_broadcast_device.mode == TICKDEV_MODE_PERIODIC)
410 tick_broadcast_start_periodic(bc);
412 tick_broadcast_setup_oneshot(bc);
414 raw_spin_unlock(&tick_broadcast_lock);
416 EXPORT_SYMBOL_GPL(tick_broadcast_control);
419 * Set the periodic handler depending on broadcast on/off
421 void tick_set_periodic_handler(struct clock_event_device *dev, int broadcast)
424 dev->event_handler = tick_handle_periodic;
426 dev->event_handler = tick_handle_periodic_broadcast;
429 #ifdef CONFIG_HOTPLUG_CPU
431 * Remove a CPU from broadcasting
433 void tick_shutdown_broadcast(unsigned int cpu)
435 struct clock_event_device *bc;
438 raw_spin_lock_irqsave(&tick_broadcast_lock, flags);
440 bc = tick_broadcast_device.evtdev;
441 cpumask_clear_cpu(cpu, tick_broadcast_mask);
442 cpumask_clear_cpu(cpu, tick_broadcast_on);
444 if (tick_broadcast_device.mode == TICKDEV_MODE_PERIODIC) {
445 if (bc && cpumask_empty(tick_broadcast_mask))
446 clockevents_shutdown(bc);
449 raw_spin_unlock_irqrestore(&tick_broadcast_lock, flags);
453 void tick_suspend_broadcast(void)
455 struct clock_event_device *bc;
458 raw_spin_lock_irqsave(&tick_broadcast_lock, flags);
460 bc = tick_broadcast_device.evtdev;
462 clockevents_shutdown(bc);
464 raw_spin_unlock_irqrestore(&tick_broadcast_lock, flags);
468 * This is called from tick_resume_local() on a resuming CPU. That's
469 * called from the core resume function, tick_unfreeze() and the magic XEN
472 * In none of these cases the broadcast device mode can change and the
473 * bit of the resuming CPU in the broadcast mask is safe as well.
475 bool tick_resume_check_broadcast(void)
477 if (tick_broadcast_device.mode == TICKDEV_MODE_ONESHOT)
480 return cpumask_test_cpu(smp_processor_id(), tick_broadcast_mask);
483 void tick_resume_broadcast(void)
485 struct clock_event_device *bc;
488 raw_spin_lock_irqsave(&tick_broadcast_lock, flags);
490 bc = tick_broadcast_device.evtdev;
493 clockevents_tick_resume(bc);
495 switch (tick_broadcast_device.mode) {
496 case TICKDEV_MODE_PERIODIC:
497 if (!cpumask_empty(tick_broadcast_mask))
498 tick_broadcast_start_periodic(bc);
500 case TICKDEV_MODE_ONESHOT:
501 if (!cpumask_empty(tick_broadcast_mask))
502 tick_resume_broadcast_oneshot(bc);
506 raw_spin_unlock_irqrestore(&tick_broadcast_lock, flags);
509 #ifdef CONFIG_TICK_ONESHOT
511 static cpumask_var_t tick_broadcast_oneshot_mask;
512 static cpumask_var_t tick_broadcast_pending_mask;
513 static cpumask_var_t tick_broadcast_force_mask;
516 * Exposed for debugging: see timer_list.c
518 struct cpumask *tick_get_broadcast_oneshot_mask(void)
520 return tick_broadcast_oneshot_mask;
524 * Called before going idle with interrupts disabled. Checks whether a
525 * broadcast event from the other core is about to happen. We detected
526 * that in tick_broadcast_oneshot_control(). The callsite can use this
527 * to avoid a deep idle transition as we are about to get the
528 * broadcast IPI right away.
530 int tick_check_broadcast_expired(void)
532 return cpumask_test_cpu(smp_processor_id(), tick_broadcast_force_mask);
536 * Set broadcast interrupt affinity
538 static void tick_broadcast_set_affinity(struct clock_event_device *bc,
539 const struct cpumask *cpumask)
541 if (!(bc->features & CLOCK_EVT_FEAT_DYNIRQ))
544 if (cpumask_equal(bc->cpumask, cpumask))
547 bc->cpumask = cpumask;
548 irq_set_affinity(bc->irq, bc->cpumask);
551 static void tick_broadcast_set_event(struct clock_event_device *bc, int cpu,
554 if (!clockevent_state_oneshot(bc))
555 clockevents_switch_state(bc, CLOCK_EVT_STATE_ONESHOT);
557 clockevents_program_event(bc, expires, 1);
558 tick_broadcast_set_affinity(bc, cpumask_of(cpu));
561 static void tick_resume_broadcast_oneshot(struct clock_event_device *bc)
563 clockevents_switch_state(bc, CLOCK_EVT_STATE_ONESHOT);
567 * Called from irq_enter() when idle was interrupted to reenable the
570 void tick_check_oneshot_broadcast_this_cpu(void)
572 if (cpumask_test_cpu(smp_processor_id(), tick_broadcast_oneshot_mask)) {
573 struct tick_device *td = this_cpu_ptr(&tick_cpu_device);
576 * We might be in the middle of switching over from
577 * periodic to oneshot. If the CPU has not yet
578 * switched over, leave the device alone.
580 if (td->mode == TICKDEV_MODE_ONESHOT) {
581 clockevents_switch_state(td->evtdev,
582 CLOCK_EVT_STATE_ONESHOT);
588 * Handle oneshot mode broadcasting
590 static void tick_handle_oneshot_broadcast(struct clock_event_device *dev)
592 struct tick_device *td;
593 ktime_t now, next_event;
594 int cpu, next_cpu = 0;
597 raw_spin_lock(&tick_broadcast_lock);
598 dev->next_event.tv64 = KTIME_MAX;
599 next_event.tv64 = KTIME_MAX;
600 cpumask_clear(tmpmask);
602 /* Find all expired events */
603 for_each_cpu(cpu, tick_broadcast_oneshot_mask) {
604 td = &per_cpu(tick_cpu_device, cpu);
605 if (td->evtdev->next_event.tv64 <= now.tv64) {
606 cpumask_set_cpu(cpu, tmpmask);
608 * Mark the remote cpu in the pending mask, so
609 * it can avoid reprogramming the cpu local
610 * timer in tick_broadcast_oneshot_control().
612 cpumask_set_cpu(cpu, tick_broadcast_pending_mask);
613 } else if (td->evtdev->next_event.tv64 < next_event.tv64) {
614 next_event.tv64 = td->evtdev->next_event.tv64;
620 * Remove the current cpu from the pending mask. The event is
621 * delivered immediately in tick_do_broadcast() !
623 cpumask_clear_cpu(smp_processor_id(), tick_broadcast_pending_mask);
625 /* Take care of enforced broadcast requests */
626 cpumask_or(tmpmask, tmpmask, tick_broadcast_force_mask);
627 cpumask_clear(tick_broadcast_force_mask);
630 * Sanity check. Catch the case where we try to broadcast to
633 if (WARN_ON_ONCE(!cpumask_subset(tmpmask, cpu_online_mask)))
634 cpumask_and(tmpmask, tmpmask, cpu_online_mask);
637 * Wakeup the cpus which have an expired event.
639 bc_local = tick_do_broadcast(tmpmask);
642 * Two reasons for reprogram:
644 * - The global event did not expire any CPU local
645 * events. This happens in dyntick mode, as the maximum PIT
646 * delta is quite small.
648 * - There are pending events on sleeping CPUs which were not
651 if (next_event.tv64 != KTIME_MAX)
652 tick_broadcast_set_event(dev, next_cpu, next_event);
654 raw_spin_unlock(&tick_broadcast_lock);
657 td = this_cpu_ptr(&tick_cpu_device);
658 td->evtdev->event_handler(td->evtdev);
662 static int broadcast_needs_cpu(struct clock_event_device *bc, int cpu)
664 if (!(bc->features & CLOCK_EVT_FEAT_HRTIMER))
666 if (bc->next_event.tv64 == KTIME_MAX)
668 return bc->bound_on == cpu ? -EBUSY : 0;
671 static void broadcast_shutdown_local(struct clock_event_device *bc,
672 struct clock_event_device *dev)
675 * For hrtimer based broadcasting we cannot shutdown the cpu
676 * local device if our own event is the first one to expire or
677 * if we own the broadcast timer.
679 if (bc->features & CLOCK_EVT_FEAT_HRTIMER) {
680 if (broadcast_needs_cpu(bc, smp_processor_id()))
682 if (dev->next_event.tv64 < bc->next_event.tv64)
685 clockevents_switch_state(dev, CLOCK_EVT_STATE_SHUTDOWN);
688 int __tick_broadcast_oneshot_control(enum tick_broadcast_state state)
690 struct clock_event_device *bc, *dev;
691 struct tick_device *td;
696 * If there is no broadcast device, tell the caller not to go
699 if (!tick_broadcast_device.evtdev)
703 * Periodic mode does not care about the enter/exit of power
706 if (tick_broadcast_device.mode == TICKDEV_MODE_PERIODIC)
710 * We are called with preemtion disabled from the depth of the
711 * idle code, so we can't be moved away.
713 td = this_cpu_ptr(&tick_cpu_device);
716 raw_spin_lock(&tick_broadcast_lock);
717 bc = tick_broadcast_device.evtdev;
718 cpu = smp_processor_id();
720 if (state == TICK_BROADCAST_ENTER) {
721 if (!cpumask_test_and_set_cpu(cpu, tick_broadcast_oneshot_mask)) {
722 WARN_ON_ONCE(cpumask_test_cpu(cpu, tick_broadcast_pending_mask));
723 broadcast_shutdown_local(bc, dev);
725 * We only reprogram the broadcast timer if we
726 * did not mark ourself in the force mask and
727 * if the cpu local event is earlier than the
728 * broadcast event. If the current CPU is in
729 * the force mask, then we are going to be
730 * woken by the IPI right away.
732 if (!cpumask_test_cpu(cpu, tick_broadcast_force_mask) &&
733 dev->next_event.tv64 < bc->next_event.tv64)
734 tick_broadcast_set_event(bc, cpu, dev->next_event);
737 * If the current CPU owns the hrtimer broadcast
738 * mechanism, it cannot go deep idle and we remove the
739 * CPU from the broadcast mask. We don't have to go
740 * through the EXIT path as the local timer is not
743 ret = broadcast_needs_cpu(bc, cpu);
745 cpumask_clear_cpu(cpu, tick_broadcast_oneshot_mask);
747 if (cpumask_test_and_clear_cpu(cpu, tick_broadcast_oneshot_mask)) {
748 clockevents_switch_state(dev, CLOCK_EVT_STATE_ONESHOT);
750 * The cpu which was handling the broadcast
751 * timer marked this cpu in the broadcast
752 * pending mask and fired the broadcast
753 * IPI. So we are going to handle the expired
754 * event anyway via the broadcast IPI
755 * handler. No need to reprogram the timer
756 * with an already expired event.
758 if (cpumask_test_and_clear_cpu(cpu,
759 tick_broadcast_pending_mask))
763 * Bail out if there is no next event.
765 if (dev->next_event.tv64 == KTIME_MAX)
768 * If the pending bit is not set, then we are
769 * either the CPU handling the broadcast
770 * interrupt or we got woken by something else.
772 * We are not longer in the broadcast mask, so
773 * if the cpu local expiry time is already
774 * reached, we would reprogram the cpu local
775 * timer with an already expired event.
777 * This can lead to a ping-pong when we return
778 * to idle and therefor rearm the broadcast
779 * timer before the cpu local timer was able
780 * to fire. This happens because the forced
781 * reprogramming makes sure that the event
782 * will happen in the future and depending on
783 * the min_delta setting this might be far
784 * enough out that the ping-pong starts.
786 * If the cpu local next_event has expired
787 * then we know that the broadcast timer
788 * next_event has expired as well and
789 * broadcast is about to be handled. So we
790 * avoid reprogramming and enforce that the
791 * broadcast handler, which did not run yet,
792 * will invoke the cpu local handler.
794 * We cannot call the handler directly from
795 * here, because we might be in a NOHZ phase
796 * and we did not go through the irq_enter()
800 if (dev->next_event.tv64 <= now.tv64) {
801 cpumask_set_cpu(cpu, tick_broadcast_force_mask);
805 * We got woken by something else. Reprogram
806 * the cpu local timer device.
808 tick_program_event(dev->next_event, 1);
812 raw_spin_unlock(&tick_broadcast_lock);
815 EXPORT_SYMBOL_GPL(tick_broadcast_oneshot_control);
818 * Reset the one shot broadcast for a cpu
820 * Called with tick_broadcast_lock held
822 static void tick_broadcast_clear_oneshot(int cpu)
824 cpumask_clear_cpu(cpu, tick_broadcast_oneshot_mask);
825 cpumask_clear_cpu(cpu, tick_broadcast_pending_mask);
828 static void tick_broadcast_init_next_event(struct cpumask *mask,
831 struct tick_device *td;
834 for_each_cpu(cpu, mask) {
835 td = &per_cpu(tick_cpu_device, cpu);
837 td->evtdev->next_event = expires;
842 * tick_broadcast_setup_oneshot - setup the broadcast device
844 void tick_broadcast_setup_oneshot(struct clock_event_device *bc)
846 int cpu = smp_processor_id();
848 /* Set it up only once ! */
849 if (bc->event_handler != tick_handle_oneshot_broadcast) {
850 int was_periodic = clockevent_state_periodic(bc);
852 bc->event_handler = tick_handle_oneshot_broadcast;
855 * We must be careful here. There might be other CPUs
856 * waiting for periodic broadcast. We need to set the
857 * oneshot_mask bits for those and program the
858 * broadcast device to fire.
860 cpumask_copy(tmpmask, tick_broadcast_mask);
861 cpumask_clear_cpu(cpu, tmpmask);
862 cpumask_or(tick_broadcast_oneshot_mask,
863 tick_broadcast_oneshot_mask, tmpmask);
865 if (was_periodic && !cpumask_empty(tmpmask)) {
866 clockevents_switch_state(bc, CLOCK_EVT_STATE_ONESHOT);
867 tick_broadcast_init_next_event(tmpmask,
869 tick_broadcast_set_event(bc, cpu, tick_next_period);
871 bc->next_event.tv64 = KTIME_MAX;
874 * The first cpu which switches to oneshot mode sets
875 * the bit for all other cpus which are in the general
876 * (periodic) broadcast mask. So the bit is set and
877 * would prevent the first broadcast enter after this
878 * to program the bc device.
880 tick_broadcast_clear_oneshot(cpu);
885 * Select oneshot operating mode for the broadcast device
887 void tick_broadcast_switch_to_oneshot(void)
889 struct clock_event_device *bc;
892 raw_spin_lock_irqsave(&tick_broadcast_lock, flags);
894 tick_broadcast_device.mode = TICKDEV_MODE_ONESHOT;
895 bc = tick_broadcast_device.evtdev;
897 tick_broadcast_setup_oneshot(bc);
899 raw_spin_unlock_irqrestore(&tick_broadcast_lock, flags);
902 #ifdef CONFIG_HOTPLUG_CPU
903 void hotplug_cpu__broadcast_tick_pull(int deadcpu)
905 struct clock_event_device *bc;
908 raw_spin_lock_irqsave(&tick_broadcast_lock, flags);
909 bc = tick_broadcast_device.evtdev;
911 if (bc && broadcast_needs_cpu(bc, deadcpu)) {
912 /* This moves the broadcast assignment to this CPU: */
913 clockevents_program_event(bc, bc->next_event, 1);
915 raw_spin_unlock_irqrestore(&tick_broadcast_lock, flags);
919 * Remove a dead CPU from broadcasting
921 void tick_shutdown_broadcast_oneshot(unsigned int cpu)
925 raw_spin_lock_irqsave(&tick_broadcast_lock, flags);
928 * Clear the broadcast masks for the dead cpu, but do not stop
929 * the broadcast device!
931 cpumask_clear_cpu(cpu, tick_broadcast_oneshot_mask);
932 cpumask_clear_cpu(cpu, tick_broadcast_pending_mask);
933 cpumask_clear_cpu(cpu, tick_broadcast_force_mask);
935 raw_spin_unlock_irqrestore(&tick_broadcast_lock, flags);
940 * Check, whether the broadcast device is in one shot mode
942 int tick_broadcast_oneshot_active(void)
944 return tick_broadcast_device.mode == TICKDEV_MODE_ONESHOT;
948 * Check whether the broadcast device supports oneshot.
950 bool tick_broadcast_oneshot_available(void)
952 struct clock_event_device *bc = tick_broadcast_device.evtdev;
954 return bc ? bc->features & CLOCK_EVT_FEAT_ONESHOT : false;
958 int __tick_broadcast_oneshot_control(enum tick_broadcast_state state)
960 struct clock_event_device *bc = tick_broadcast_device.evtdev;
962 if (!bc || (bc->features & CLOCK_EVT_FEAT_HRTIMER))
969 void __init tick_broadcast_init(void)
971 zalloc_cpumask_var(&tick_broadcast_mask, GFP_NOWAIT);
972 zalloc_cpumask_var(&tick_broadcast_on, GFP_NOWAIT);
973 zalloc_cpumask_var(&tmpmask, GFP_NOWAIT);
974 #ifdef CONFIG_TICK_ONESHOT
975 zalloc_cpumask_var(&tick_broadcast_oneshot_mask, GFP_NOWAIT);
976 zalloc_cpumask_var(&tick_broadcast_pending_mask, GFP_NOWAIT);
977 zalloc_cpumask_var(&tick_broadcast_force_mask, GFP_NOWAIT);