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.
226 ret = cpumask_test_cpu(cpu, tick_broadcast_mask);
234 raw_spin_unlock_irqrestore(&tick_broadcast_lock, flags);
238 #ifdef CONFIG_GENERIC_CLOCKEVENTS_BROADCAST
239 int tick_receive_broadcast(void)
241 struct tick_device *td = this_cpu_ptr(&tick_cpu_device);
242 struct clock_event_device *evt = td->evtdev;
247 if (!evt->event_handler)
250 evt->event_handler(evt);
256 * Broadcast the event to the cpus, which are set in the mask (mangled).
258 static void tick_do_broadcast(struct cpumask *mask)
260 int cpu = smp_processor_id();
261 struct tick_device *td;
264 * Check, if the current cpu is in the mask
266 if (cpumask_test_cpu(cpu, mask)) {
267 cpumask_clear_cpu(cpu, mask);
268 td = &per_cpu(tick_cpu_device, cpu);
269 td->evtdev->event_handler(td->evtdev);
272 if (!cpumask_empty(mask)) {
274 * It might be necessary to actually check whether the devices
275 * have different broadcast functions. For now, just use the
276 * one of the first device. This works as long as we have this
277 * misfeature only on x86 (lapic)
279 td = &per_cpu(tick_cpu_device, cpumask_first(mask));
280 td->evtdev->broadcast(mask);
285 * Periodic broadcast:
286 * - invoke the broadcast handlers
288 static void tick_do_periodic_broadcast(void)
290 cpumask_and(tmpmask, cpu_online_mask, tick_broadcast_mask);
291 tick_do_broadcast(tmpmask);
295 * Event handler for periodic broadcast ticks
297 static void tick_handle_periodic_broadcast(struct clock_event_device *dev)
301 raw_spin_lock(&tick_broadcast_lock);
303 tick_do_periodic_broadcast();
306 * The device is in periodic mode. No reprogramming necessary:
308 if (dev->state == CLOCK_EVT_STATE_PERIODIC)
312 * Setup the next period for devices, which do not have
313 * periodic mode. We read dev->next_event first and add to it
314 * when the event already expired. clockevents_program_event()
315 * sets dev->next_event only when the event is really
316 * programmed to the device.
318 for (next = dev->next_event; ;) {
319 next = ktime_add(next, tick_period);
321 if (!clockevents_program_event(dev, next, false))
323 tick_do_periodic_broadcast();
326 raw_spin_unlock(&tick_broadcast_lock);
330 * tick_broadcast_control - Enable/disable or force broadcast mode
331 * @mode: The selected broadcast mode
333 * Called when the system enters a state where affected tick devices
334 * might stop. Note: TICK_BROADCAST_FORCE cannot be undone.
336 * Called with interrupts disabled, so clockevents_lock is not
337 * required here because the local clock event device cannot go away
340 void tick_broadcast_control(enum tick_broadcast_mode mode)
342 struct clock_event_device *bc, *dev;
343 struct tick_device *td;
346 td = this_cpu_ptr(&tick_cpu_device);
350 * Is the device not affected by the powerstate ?
352 if (!dev || !(dev->features & CLOCK_EVT_FEAT_C3STOP))
355 if (!tick_device_is_functional(dev))
358 raw_spin_lock(&tick_broadcast_lock);
359 cpu = smp_processor_id();
360 bc = tick_broadcast_device.evtdev;
361 bc_stopped = cpumask_empty(tick_broadcast_mask);
364 case TICK_BROADCAST_FORCE:
365 tick_broadcast_forced = 1;
366 case TICK_BROADCAST_ON:
367 cpumask_set_cpu(cpu, tick_broadcast_on);
368 if (!cpumask_test_and_set_cpu(cpu, tick_broadcast_mask)) {
369 if (tick_broadcast_device.mode ==
370 TICKDEV_MODE_PERIODIC)
371 clockevents_shutdown(dev);
375 case TICK_BROADCAST_OFF:
376 if (tick_broadcast_forced)
378 cpumask_clear_cpu(cpu, tick_broadcast_on);
379 if (!tick_device_is_functional(dev))
381 if (cpumask_test_and_clear_cpu(cpu, tick_broadcast_mask)) {
382 if (tick_broadcast_device.mode ==
383 TICKDEV_MODE_PERIODIC)
384 tick_setup_periodic(dev, 0);
389 if (cpumask_empty(tick_broadcast_mask)) {
391 clockevents_shutdown(bc);
392 } else if (bc_stopped) {
393 if (tick_broadcast_device.mode == TICKDEV_MODE_PERIODIC)
394 tick_broadcast_start_periodic(bc);
396 tick_broadcast_setup_oneshot(bc);
398 raw_spin_unlock(&tick_broadcast_lock);
400 EXPORT_SYMBOL_GPL(tick_broadcast_control);
403 * Set the periodic handler depending on broadcast on/off
405 void tick_set_periodic_handler(struct clock_event_device *dev, int broadcast)
408 dev->event_handler = tick_handle_periodic;
410 dev->event_handler = tick_handle_periodic_broadcast;
414 * Remove a CPU from broadcasting
416 void tick_shutdown_broadcast(unsigned int *cpup)
418 struct clock_event_device *bc;
420 unsigned int cpu = *cpup;
422 raw_spin_lock_irqsave(&tick_broadcast_lock, flags);
424 bc = tick_broadcast_device.evtdev;
425 cpumask_clear_cpu(cpu, tick_broadcast_mask);
426 cpumask_clear_cpu(cpu, tick_broadcast_on);
428 if (tick_broadcast_device.mode == TICKDEV_MODE_PERIODIC) {
429 if (bc && cpumask_empty(tick_broadcast_mask))
430 clockevents_shutdown(bc);
433 raw_spin_unlock_irqrestore(&tick_broadcast_lock, flags);
436 void tick_suspend_broadcast(void)
438 struct clock_event_device *bc;
441 raw_spin_lock_irqsave(&tick_broadcast_lock, flags);
443 bc = tick_broadcast_device.evtdev;
445 clockevents_shutdown(bc);
447 raw_spin_unlock_irqrestore(&tick_broadcast_lock, flags);
451 * This is called from tick_resume_local() on a resuming CPU. That's
452 * called from the core resume function, tick_unfreeze() and the magic XEN
455 * In none of these cases the broadcast device mode can change and the
456 * bit of the resuming CPU in the broadcast mask is safe as well.
458 bool tick_resume_check_broadcast(void)
460 if (tick_broadcast_device.mode == TICKDEV_MODE_ONESHOT)
463 return cpumask_test_cpu(smp_processor_id(), tick_broadcast_mask);
466 void tick_resume_broadcast(void)
468 struct clock_event_device *bc;
471 raw_spin_lock_irqsave(&tick_broadcast_lock, flags);
473 bc = tick_broadcast_device.evtdev;
476 clockevents_tick_resume(bc);
478 switch (tick_broadcast_device.mode) {
479 case TICKDEV_MODE_PERIODIC:
480 if (!cpumask_empty(tick_broadcast_mask))
481 tick_broadcast_start_periodic(bc);
483 case TICKDEV_MODE_ONESHOT:
484 if (!cpumask_empty(tick_broadcast_mask))
485 tick_resume_broadcast_oneshot(bc);
489 raw_spin_unlock_irqrestore(&tick_broadcast_lock, flags);
492 #ifdef CONFIG_TICK_ONESHOT
494 static cpumask_var_t tick_broadcast_oneshot_mask;
495 static cpumask_var_t tick_broadcast_pending_mask;
496 static cpumask_var_t tick_broadcast_force_mask;
499 * Exposed for debugging: see timer_list.c
501 struct cpumask *tick_get_broadcast_oneshot_mask(void)
503 return tick_broadcast_oneshot_mask;
507 * Called before going idle with interrupts disabled. Checks whether a
508 * broadcast event from the other core is about to happen. We detected
509 * that in tick_broadcast_oneshot_control(). The callsite can use this
510 * to avoid a deep idle transition as we are about to get the
511 * broadcast IPI right away.
513 int tick_check_broadcast_expired(void)
515 return cpumask_test_cpu(smp_processor_id(), tick_broadcast_force_mask);
519 * Set broadcast interrupt affinity
521 static void tick_broadcast_set_affinity(struct clock_event_device *bc,
522 const struct cpumask *cpumask)
524 if (!(bc->features & CLOCK_EVT_FEAT_DYNIRQ))
527 if (cpumask_equal(bc->cpumask, cpumask))
530 bc->cpumask = cpumask;
531 irq_set_affinity(bc->irq, bc->cpumask);
534 static int tick_broadcast_set_event(struct clock_event_device *bc, int cpu,
535 ktime_t expires, int force)
539 if (bc->state != CLOCK_EVT_STATE_ONESHOT)
540 clockevents_set_state(bc, CLOCK_EVT_STATE_ONESHOT);
542 ret = clockevents_program_event(bc, expires, force);
544 tick_broadcast_set_affinity(bc, cpumask_of(cpu));
548 static void tick_resume_broadcast_oneshot(struct clock_event_device *bc)
550 clockevents_set_state(bc, CLOCK_EVT_STATE_ONESHOT);
554 * Called from irq_enter() when idle was interrupted to reenable the
557 void tick_check_oneshot_broadcast_this_cpu(void)
559 if (cpumask_test_cpu(smp_processor_id(), tick_broadcast_oneshot_mask)) {
560 struct tick_device *td = this_cpu_ptr(&tick_cpu_device);
563 * We might be in the middle of switching over from
564 * periodic to oneshot. If the CPU has not yet
565 * switched over, leave the device alone.
567 if (td->mode == TICKDEV_MODE_ONESHOT) {
568 clockevents_set_state(td->evtdev,
569 CLOCK_EVT_STATE_ONESHOT);
575 * Handle oneshot mode broadcasting
577 static void tick_handle_oneshot_broadcast(struct clock_event_device *dev)
579 struct tick_device *td;
580 ktime_t now, next_event;
581 int cpu, next_cpu = 0;
583 raw_spin_lock(&tick_broadcast_lock);
585 dev->next_event.tv64 = KTIME_MAX;
586 next_event.tv64 = KTIME_MAX;
587 cpumask_clear(tmpmask);
589 /* Find all expired events */
590 for_each_cpu(cpu, tick_broadcast_oneshot_mask) {
591 td = &per_cpu(tick_cpu_device, cpu);
592 if (td->evtdev->next_event.tv64 <= now.tv64) {
593 cpumask_set_cpu(cpu, tmpmask);
595 * Mark the remote cpu in the pending mask, so
596 * it can avoid reprogramming the cpu local
597 * timer in tick_broadcast_oneshot_control().
599 cpumask_set_cpu(cpu, tick_broadcast_pending_mask);
600 } else if (td->evtdev->next_event.tv64 < next_event.tv64) {
601 next_event.tv64 = td->evtdev->next_event.tv64;
607 * Remove the current cpu from the pending mask. The event is
608 * delivered immediately in tick_do_broadcast() !
610 cpumask_clear_cpu(smp_processor_id(), tick_broadcast_pending_mask);
612 /* Take care of enforced broadcast requests */
613 cpumask_or(tmpmask, tmpmask, tick_broadcast_force_mask);
614 cpumask_clear(tick_broadcast_force_mask);
617 * Sanity check. Catch the case where we try to broadcast to
620 if (WARN_ON_ONCE(!cpumask_subset(tmpmask, cpu_online_mask)))
621 cpumask_and(tmpmask, tmpmask, cpu_online_mask);
624 * Wakeup the cpus which have an expired event.
626 tick_do_broadcast(tmpmask);
629 * Two reasons for reprogram:
631 * - The global event did not expire any CPU local
632 * events. This happens in dyntick mode, as the maximum PIT
633 * delta is quite small.
635 * - There are pending events on sleeping CPUs which were not
638 if (next_event.tv64 != KTIME_MAX) {
640 * Rearm the broadcast device. If event expired,
643 if (tick_broadcast_set_event(dev, next_cpu, next_event, 0))
646 raw_spin_unlock(&tick_broadcast_lock);
649 static int broadcast_needs_cpu(struct clock_event_device *bc, int cpu)
651 if (!(bc->features & CLOCK_EVT_FEAT_HRTIMER))
653 if (bc->next_event.tv64 == KTIME_MAX)
655 return bc->bound_on == cpu ? -EBUSY : 0;
658 static void broadcast_shutdown_local(struct clock_event_device *bc,
659 struct clock_event_device *dev)
662 * For hrtimer based broadcasting we cannot shutdown the cpu
663 * local device if our own event is the first one to expire or
664 * if we own the broadcast timer.
666 if (bc->features & CLOCK_EVT_FEAT_HRTIMER) {
667 if (broadcast_needs_cpu(bc, smp_processor_id()))
669 if (dev->next_event.tv64 < bc->next_event.tv64)
672 clockevents_set_state(dev, CLOCK_EVT_STATE_SHUTDOWN);
675 void hotplug_cpu__broadcast_tick_pull(int deadcpu)
677 struct clock_event_device *bc;
680 raw_spin_lock_irqsave(&tick_broadcast_lock, flags);
681 bc = tick_broadcast_device.evtdev;
683 if (bc && broadcast_needs_cpu(bc, deadcpu)) {
684 /* This moves the broadcast assignment to this CPU: */
685 clockevents_program_event(bc, bc->next_event, 1);
687 raw_spin_unlock_irqrestore(&tick_broadcast_lock, flags);
691 * tick_broadcast_oneshot_control - Enter/exit broadcast oneshot mode
692 * @state: The target state (enter/exit)
694 * The system enters/leaves a state, where affected devices might stop
695 * Returns 0 on success, -EBUSY if the cpu is used to broadcast wakeups.
697 * Called with interrupts disabled, so clockevents_lock is not
698 * required here because the local clock event device cannot go away
701 int tick_broadcast_oneshot_control(enum tick_broadcast_state state)
703 struct clock_event_device *bc, *dev;
704 struct tick_device *td;
709 * Periodic mode does not care about the enter/exit of power
712 if (tick_broadcast_device.mode == TICKDEV_MODE_PERIODIC)
716 * We are called with preemtion disabled from the depth of the
717 * idle code, so we can't be moved away.
719 td = this_cpu_ptr(&tick_cpu_device);
722 if (!(dev->features & CLOCK_EVT_FEAT_C3STOP))
725 raw_spin_lock(&tick_broadcast_lock);
726 bc = tick_broadcast_device.evtdev;
727 cpu = smp_processor_id();
729 if (state == TICK_BROADCAST_ENTER) {
730 if (!cpumask_test_and_set_cpu(cpu, tick_broadcast_oneshot_mask)) {
731 WARN_ON_ONCE(cpumask_test_cpu(cpu, tick_broadcast_pending_mask));
732 broadcast_shutdown_local(bc, dev);
734 * We only reprogram the broadcast timer if we
735 * did not mark ourself in the force mask and
736 * if the cpu local event is earlier than the
737 * broadcast event. If the current CPU is in
738 * the force mask, then we are going to be
739 * woken by the IPI right away.
741 if (!cpumask_test_cpu(cpu, tick_broadcast_force_mask) &&
742 dev->next_event.tv64 < bc->next_event.tv64)
743 tick_broadcast_set_event(bc, cpu, dev->next_event, 1);
746 * If the current CPU owns the hrtimer broadcast
747 * mechanism, it cannot go deep idle and we remove the
748 * CPU from the broadcast mask. We don't have to go
749 * through the EXIT path as the local timer is not
752 ret = broadcast_needs_cpu(bc, cpu);
754 cpumask_clear_cpu(cpu, tick_broadcast_oneshot_mask);
756 if (cpumask_test_and_clear_cpu(cpu, tick_broadcast_oneshot_mask)) {
757 clockevents_set_state(dev, CLOCK_EVT_STATE_ONESHOT);
759 * The cpu which was handling the broadcast
760 * timer marked this cpu in the broadcast
761 * pending mask and fired the broadcast
762 * IPI. So we are going to handle the expired
763 * event anyway via the broadcast IPI
764 * handler. No need to reprogram the timer
765 * with an already expired event.
767 if (cpumask_test_and_clear_cpu(cpu,
768 tick_broadcast_pending_mask))
772 * Bail out if there is no next event.
774 if (dev->next_event.tv64 == KTIME_MAX)
777 * If the pending bit is not set, then we are
778 * either the CPU handling the broadcast
779 * interrupt or we got woken by something else.
781 * We are not longer in the broadcast mask, so
782 * if the cpu local expiry time is already
783 * reached, we would reprogram the cpu local
784 * timer with an already expired event.
786 * This can lead to a ping-pong when we return
787 * to idle and therefor rearm the broadcast
788 * timer before the cpu local timer was able
789 * to fire. This happens because the forced
790 * reprogramming makes sure that the event
791 * will happen in the future and depending on
792 * the min_delta setting this might be far
793 * enough out that the ping-pong starts.
795 * If the cpu local next_event has expired
796 * then we know that the broadcast timer
797 * next_event has expired as well and
798 * broadcast is about to be handled. So we
799 * avoid reprogramming and enforce that the
800 * broadcast handler, which did not run yet,
801 * will invoke the cpu local handler.
803 * We cannot call the handler directly from
804 * here, because we might be in a NOHZ phase
805 * and we did not go through the irq_enter()
809 if (dev->next_event.tv64 <= now.tv64) {
810 cpumask_set_cpu(cpu, tick_broadcast_force_mask);
814 * We got woken by something else. Reprogram
815 * the cpu local timer device.
817 tick_program_event(dev->next_event, 1);
821 raw_spin_unlock(&tick_broadcast_lock);
824 EXPORT_SYMBOL_GPL(tick_broadcast_oneshot_control);
827 * Reset the one shot broadcast for a cpu
829 * Called with tick_broadcast_lock held
831 static void tick_broadcast_clear_oneshot(int cpu)
833 cpumask_clear_cpu(cpu, tick_broadcast_oneshot_mask);
834 cpumask_clear_cpu(cpu, tick_broadcast_pending_mask);
837 static void tick_broadcast_init_next_event(struct cpumask *mask,
840 struct tick_device *td;
843 for_each_cpu(cpu, mask) {
844 td = &per_cpu(tick_cpu_device, cpu);
846 td->evtdev->next_event = expires;
851 * tick_broadcast_setup_oneshot - setup the broadcast device
853 void tick_broadcast_setup_oneshot(struct clock_event_device *bc)
855 int cpu = smp_processor_id();
857 /* Set it up only once ! */
858 if (bc->event_handler != tick_handle_oneshot_broadcast) {
859 int was_periodic = bc->state == CLOCK_EVT_STATE_PERIODIC;
861 bc->event_handler = tick_handle_oneshot_broadcast;
864 * We must be careful here. There might be other CPUs
865 * waiting for periodic broadcast. We need to set the
866 * oneshot_mask bits for those and program the
867 * broadcast device to fire.
869 cpumask_copy(tmpmask, tick_broadcast_mask);
870 cpumask_clear_cpu(cpu, tmpmask);
871 cpumask_or(tick_broadcast_oneshot_mask,
872 tick_broadcast_oneshot_mask, tmpmask);
874 if (was_periodic && !cpumask_empty(tmpmask)) {
875 clockevents_set_state(bc, CLOCK_EVT_STATE_ONESHOT);
876 tick_broadcast_init_next_event(tmpmask,
878 tick_broadcast_set_event(bc, cpu, tick_next_period, 1);
880 bc->next_event.tv64 = KTIME_MAX;
883 * The first cpu which switches to oneshot mode sets
884 * the bit for all other cpus which are in the general
885 * (periodic) broadcast mask. So the bit is set and
886 * would prevent the first broadcast enter after this
887 * to program the bc device.
889 tick_broadcast_clear_oneshot(cpu);
894 * Select oneshot operating mode for the broadcast device
896 void tick_broadcast_switch_to_oneshot(void)
898 struct clock_event_device *bc;
901 raw_spin_lock_irqsave(&tick_broadcast_lock, flags);
903 tick_broadcast_device.mode = TICKDEV_MODE_ONESHOT;
904 bc = tick_broadcast_device.evtdev;
906 tick_broadcast_setup_oneshot(bc);
908 raw_spin_unlock_irqrestore(&tick_broadcast_lock, flags);
913 * Remove a dead CPU from broadcasting
915 void tick_shutdown_broadcast_oneshot(unsigned int *cpup)
918 unsigned int cpu = *cpup;
920 raw_spin_lock_irqsave(&tick_broadcast_lock, flags);
923 * Clear the broadcast masks for the dead cpu, but do not stop
924 * the broadcast device!
926 cpumask_clear_cpu(cpu, tick_broadcast_oneshot_mask);
927 cpumask_clear_cpu(cpu, tick_broadcast_pending_mask);
928 cpumask_clear_cpu(cpu, tick_broadcast_force_mask);
930 raw_spin_unlock_irqrestore(&tick_broadcast_lock, flags);
934 * Check, whether the broadcast device is in one shot mode
936 int tick_broadcast_oneshot_active(void)
938 return tick_broadcast_device.mode == TICKDEV_MODE_ONESHOT;
942 * Check whether the broadcast device supports oneshot.
944 bool tick_broadcast_oneshot_available(void)
946 struct clock_event_device *bc = tick_broadcast_device.evtdev;
948 return bc ? bc->features & CLOCK_EVT_FEAT_ONESHOT : false;
953 void __init tick_broadcast_init(void)
955 zalloc_cpumask_var(&tick_broadcast_mask, GFP_NOWAIT);
956 zalloc_cpumask_var(&tick_broadcast_on, GFP_NOWAIT);
957 zalloc_cpumask_var(&tmpmask, GFP_NOWAIT);
958 #ifdef CONFIG_TICK_ONESHOT
959 zalloc_cpumask_var(&tick_broadcast_oneshot_mask, GFP_NOWAIT);
960 zalloc_cpumask_var(&tick_broadcast_pending_mask, GFP_NOWAIT);
961 zalloc_cpumask_var(&tick_broadcast_force_mask, GFP_NOWAIT);