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1/*
2 * linux/kernel/time/tick-broadcast.c
3 *
4 * This file contains functions which emulate a local clock-event
5 * device via a broadcast event source.
6 *
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
10 *
11 * This code is licenced under the GPL version 2. For details see
12 * kernel-base/COPYING.
13 */
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>
23
24#include "tick-internal.h"
25
26/*
27 * Broadcast support for broken x86 hardware, where the local apic
28 * timer stops in C3 state.
29 */
30
31static struct tick_device tick_broadcast_device;
32static cpumask_var_t tick_broadcast_mask;
33static cpumask_var_t tick_broadcast_on;
34static cpumask_var_t tmpmask;
35static DEFINE_RAW_SPINLOCK(tick_broadcast_lock);
36static int tick_broadcast_forced;
37
38#ifdef CONFIG_TICK_ONESHOT
39static void tick_broadcast_clear_oneshot(int cpu);
40static void tick_resume_broadcast_oneshot(struct clock_event_device *bc);
41#else
42static inline void tick_broadcast_clear_oneshot(int cpu) { }
43static inline void tick_resume_broadcast_oneshot(struct clock_event_device *bc) { }
44#endif
45
46/*
47 * Debugging: see timer_list.c
48 */
49struct tick_device *tick_get_broadcast_device(void)
50{
51 return &tick_broadcast_device;
52}
53
54struct cpumask *tick_get_broadcast_mask(void)
55{
56 return tick_broadcast_mask;
57}
58
59/*
60 * Start the device in periodic mode
61 */
62static void tick_broadcast_start_periodic(struct clock_event_device *bc)
63{
64 if (bc)
65 tick_setup_periodic(bc, 1);
66}
67
68/*
69 * Check, if the device can be utilized as broadcast device:
70 */
71static bool tick_check_broadcast_device(struct clock_event_device *curdev,
72 struct clock_event_device *newdev)
73{
74 if ((newdev->features & CLOCK_EVT_FEAT_DUMMY) ||
75 (newdev->features & CLOCK_EVT_FEAT_PERCPU) ||
76 (newdev->features & CLOCK_EVT_FEAT_C3STOP))
77 return false;
78
79 if (tick_broadcast_device.mode == TICKDEV_MODE_ONESHOT &&
80 !(newdev->features & CLOCK_EVT_FEAT_ONESHOT))
81 return false;
82
83 return !curdev || newdev->rating > curdev->rating;
84}
85
86/*
87 * Conditionally install/replace broadcast device
88 */
89void tick_install_broadcast_device(struct clock_event_device *dev)
90{
91 struct clock_event_device *cur = tick_broadcast_device.evtdev;
92
93 if (!tick_check_broadcast_device(cur, dev))
94 return;
95
96 if (!try_module_get(dev->owner))
97 return;
98
99 clockevents_exchange_device(cur, dev);
100 if (cur)
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);
105 /*
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
111 * forever.
112 */
113 if (dev->features & CLOCK_EVT_FEAT_ONESHOT)
114 tick_clock_notify();
115}
116
117/*
118 * Check, if the device is the broadcast device
119 */
120int tick_is_broadcast_device(struct clock_event_device *dev)
121{
122 return (dev && tick_broadcast_device.evtdev == dev);
123}
124
125int tick_broadcast_update_freq(struct clock_event_device *dev, u32 freq)
126{
127 int ret = -ENODEV;
128
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);
133 }
134 return ret;
135}
136
137
138static void err_broadcast(const struct cpumask *mask)
139{
140 pr_crit_once("Failed to broadcast timer tick. Some CPUs may be unresponsive.\n");
141}
142
143static void tick_device_setup_broadcast_func(struct clock_event_device *dev)
144{
145 if (!dev->broadcast)
146 dev->broadcast = tick_broadcast;
147 if (!dev->broadcast) {
148 pr_warn_once("%s depends on broadcast, but no broadcast function available\n",
149 dev->name);
150 dev->broadcast = err_broadcast;
151 }
152}
153
154/*
155 * Check, if the device is disfunctional and a place holder, which
156 * needs to be handled by the broadcast device.
157 */
158int tick_device_uses_broadcast(struct clock_event_device *dev, int cpu)
159{
160 struct clock_event_device *bc = tick_broadcast_device.evtdev;
161 unsigned long flags;
162 int ret = 0;
163
164 raw_spin_lock_irqsave(&tick_broadcast_lock, flags);
165
166 /*
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.
171 */
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);
178 else
179 tick_broadcast_setup_oneshot(bc);
180 ret = 1;
181 } else {
182 /*
183 * Clear the broadcast bit for this cpu if the
184 * device is not power state affected.
185 */
186 if (!(dev->features & CLOCK_EVT_FEAT_C3STOP))
187 cpumask_clear_cpu(cpu, tick_broadcast_mask);
188 else
189 tick_device_setup_broadcast_func(dev);
190
191 /*
192 * Clear the broadcast bit if the CPU is not in
193 * periodic broadcast on state.
194 */
195 if (!cpumask_test_cpu(cpu, tick_broadcast_on))
196 cpumask_clear_cpu(cpu, tick_broadcast_mask);
197
198 switch (tick_broadcast_device.mode) {
199 case TICKDEV_MODE_ONESHOT:
200 /*
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.
207 */
208 tick_broadcast_clear_oneshot(cpu);
209 ret = 0;
210 break;
211
212 case TICKDEV_MODE_PERIODIC:
213 /*
214 * If the system is in periodic mode, check
215 * whether the broadcast device can be
216 * switched off now.
217 */
218 if (cpumask_empty(tick_broadcast_mask) && bc)
219 clockevents_shutdown(bc);
220 /*
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
226 * hrtimer based.
227 */
228 if (bc && !(bc->features & CLOCK_EVT_FEAT_HRTIMER))
229 ret = cpumask_test_cpu(cpu, tick_broadcast_mask);
230 break;
231 default:
232 break;
233 }
234 }
235 raw_spin_unlock_irqrestore(&tick_broadcast_lock, flags);
236 return ret;
237}
238
239#ifdef CONFIG_GENERIC_CLOCKEVENTS_BROADCAST
240int tick_receive_broadcast(void)
241{
242 struct tick_device *td = this_cpu_ptr(&tick_cpu_device);
243 struct clock_event_device *evt = td->evtdev;
244
245 if (!evt)
246 return -ENODEV;
247
248 if (!evt->event_handler)
249 return -EINVAL;
250
251 evt->event_handler(evt);
252 return 0;
253}
254#endif
255
256/*
257 * Broadcast the event to the cpus, which are set in the mask (mangled).
258 */
259static bool tick_do_broadcast(struct cpumask *mask)
260{
261 int cpu = smp_processor_id();
262 struct tick_device *td;
263 bool local = false;
264
265 /*
266 * Check, if the current cpu is in the mask
267 */
268 if (cpumask_test_cpu(cpu, mask)) {
269 struct clock_event_device *bc = tick_broadcast_device.evtdev;
270
271 cpumask_clear_cpu(cpu, mask);
272 /*
273 * We only run the local handler, if the broadcast
274 * device is not hrtimer based. Otherwise we run into
275 * a hrtimer recursion.
276 *
277 * local timer_interrupt()
278 * local_handler()
279 * expire_hrtimers()
280 * bc_handler()
281 * local_handler()
282 * expire_hrtimers()
283 */
284 local = !(bc->features & CLOCK_EVT_FEAT_HRTIMER);
285 }
286
287 if (!cpumask_empty(mask)) {
288 /*
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)
293 */
294 td = &per_cpu(tick_cpu_device, cpumask_first(mask));
295 td->evtdev->broadcast(mask);
296 }
297 return local;
298}
299
300/*
301 * Periodic broadcast:
302 * - invoke the broadcast handlers
303 */
304static bool tick_do_periodic_broadcast(void)
305{
306 cpumask_and(tmpmask, cpu_online_mask, tick_broadcast_mask);
307 return tick_do_broadcast(tmpmask);
308}
309
310/*
311 * Event handler for periodic broadcast ticks
312 */
313static void tick_handle_periodic_broadcast(struct clock_event_device *dev)
314{
315 struct tick_device *td = this_cpu_ptr(&tick_cpu_device);
316 bool bc_local;
317
318 raw_spin_lock(&tick_broadcast_lock);
319
320 /* Handle spurious interrupts gracefully */
321 if (clockevent_state_shutdown(tick_broadcast_device.evtdev)) {
322 raw_spin_unlock(&tick_broadcast_lock);
323 return;
324 }
325
326 bc_local = tick_do_periodic_broadcast();
327
328 if (clockevent_state_oneshot(dev)) {
329 ktime_t next = ktime_add(dev->next_event, tick_period);
330
331 clockevents_program_event(dev, next, true);
332 }
333 raw_spin_unlock(&tick_broadcast_lock);
334
335 /*
336 * We run the handler of the local cpu after dropping
337 * tick_broadcast_lock because the handler might deadlock when
338 * trying to switch to oneshot mode.
339 */
340 if (bc_local)
341 td->evtdev->event_handler(td->evtdev);
342}
343
344/**
345 * tick_broadcast_control - Enable/disable or force broadcast mode
346 * @mode: The selected broadcast mode
347 *
348 * Called when the system enters a state where affected tick devices
349 * might stop. Note: TICK_BROADCAST_FORCE cannot be undone.
350 *
351 * Called with interrupts disabled, so clockevents_lock is not
352 * required here because the local clock event device cannot go away
353 * under us.
354 */
355void tick_broadcast_control(enum tick_broadcast_mode mode)
356{
357 struct clock_event_device *bc, *dev;
358 struct tick_device *td;
359 int cpu, bc_stopped;
360
361 td = this_cpu_ptr(&tick_cpu_device);
362 dev = td->evtdev;
363
364 /*
365 * Is the device not affected by the powerstate ?
366 */
367 if (!dev || !(dev->features & CLOCK_EVT_FEAT_C3STOP))
368 return;
369
370 if (!tick_device_is_functional(dev))
371 return;
372
373 raw_spin_lock(&tick_broadcast_lock);
374 cpu = smp_processor_id();
375 bc = tick_broadcast_device.evtdev;
376 bc_stopped = cpumask_empty(tick_broadcast_mask);
377
378 switch (mode) {
379 case TICK_BROADCAST_FORCE:
380 tick_broadcast_forced = 1;
381 case TICK_BROADCAST_ON:
382 cpumask_set_cpu(cpu, tick_broadcast_on);
383 if (!cpumask_test_and_set_cpu(cpu, tick_broadcast_mask)) {
384 /*
385 * Only shutdown the cpu local device, if:
386 *
387 * - the broadcast device exists
388 * - the broadcast device is not a hrtimer based one
389 * - the broadcast device is in periodic mode to
390 * avoid a hickup during switch to oneshot mode
391 */
392 if (bc && !(bc->features & CLOCK_EVT_FEAT_HRTIMER) &&
393 tick_broadcast_device.mode == TICKDEV_MODE_PERIODIC)
394 clockevents_shutdown(dev);
395 }
396 break;
397
398 case TICK_BROADCAST_OFF:
399 if (tick_broadcast_forced)
400 break;
401 cpumask_clear_cpu(cpu, tick_broadcast_on);
402 if (!tick_device_is_functional(dev))
403 break;
404 if (cpumask_test_and_clear_cpu(cpu, tick_broadcast_mask)) {
405 if (tick_broadcast_device.mode ==
406 TICKDEV_MODE_PERIODIC)
407 tick_setup_periodic(dev, 0);
408 }
409 break;
410 }
411
412 if (bc) {
413 if (cpumask_empty(tick_broadcast_mask)) {
414 if (!bc_stopped)
415 clockevents_shutdown(bc);
416 } else if (bc_stopped) {
417 if (tick_broadcast_device.mode == TICKDEV_MODE_PERIODIC)
418 tick_broadcast_start_periodic(bc);
419 else
420 tick_broadcast_setup_oneshot(bc);
421 }
422 }
423 raw_spin_unlock(&tick_broadcast_lock);
424}
425EXPORT_SYMBOL_GPL(tick_broadcast_control);
426
427/*
428 * Set the periodic handler depending on broadcast on/off
429 */
430void tick_set_periodic_handler(struct clock_event_device *dev, int broadcast)
431{
432 if (!broadcast)
433 dev->event_handler = tick_handle_periodic;
434 else
435 dev->event_handler = tick_handle_periodic_broadcast;
436}
437
438#ifdef CONFIG_HOTPLUG_CPU
439/*
440 * Remove a CPU from broadcasting
441 */
442void tick_shutdown_broadcast(unsigned int cpu)
443{
444 struct clock_event_device *bc;
445 unsigned long flags;
446
447 raw_spin_lock_irqsave(&tick_broadcast_lock, flags);
448
449 bc = tick_broadcast_device.evtdev;
450 cpumask_clear_cpu(cpu, tick_broadcast_mask);
451 cpumask_clear_cpu(cpu, tick_broadcast_on);
452
453 if (tick_broadcast_device.mode == TICKDEV_MODE_PERIODIC) {
454 if (bc && cpumask_empty(tick_broadcast_mask))
455 clockevents_shutdown(bc);
456 }
457
458 raw_spin_unlock_irqrestore(&tick_broadcast_lock, flags);
459}
460#endif
461
462void tick_suspend_broadcast(void)
463{
464 struct clock_event_device *bc;
465 unsigned long flags;
466
467 raw_spin_lock_irqsave(&tick_broadcast_lock, flags);
468
469 bc = tick_broadcast_device.evtdev;
470 if (bc)
471 clockevents_shutdown(bc);
472
473 raw_spin_unlock_irqrestore(&tick_broadcast_lock, flags);
474}
475
476/*
477 * This is called from tick_resume_local() on a resuming CPU. That's
478 * called from the core resume function, tick_unfreeze() and the magic XEN
479 * resume hackery.
480 *
481 * In none of these cases the broadcast device mode can change and the
482 * bit of the resuming CPU in the broadcast mask is safe as well.
483 */
484bool tick_resume_check_broadcast(void)
485{
486 if (tick_broadcast_device.mode == TICKDEV_MODE_ONESHOT)
487 return false;
488 else
489 return cpumask_test_cpu(smp_processor_id(), tick_broadcast_mask);
490}
491
492void tick_resume_broadcast(void)
493{
494 struct clock_event_device *bc;
495 unsigned long flags;
496
497 raw_spin_lock_irqsave(&tick_broadcast_lock, flags);
498
499 bc = tick_broadcast_device.evtdev;
500
501 if (bc) {
502 clockevents_tick_resume(bc);
503
504 switch (tick_broadcast_device.mode) {
505 case TICKDEV_MODE_PERIODIC:
506 if (!cpumask_empty(tick_broadcast_mask))
507 tick_broadcast_start_periodic(bc);
508 break;
509 case TICKDEV_MODE_ONESHOT:
510 if (!cpumask_empty(tick_broadcast_mask))
511 tick_resume_broadcast_oneshot(bc);
512 break;
513 }
514 }
515 raw_spin_unlock_irqrestore(&tick_broadcast_lock, flags);
516}
517
518#ifdef CONFIG_TICK_ONESHOT
519
520static cpumask_var_t tick_broadcast_oneshot_mask;
521static cpumask_var_t tick_broadcast_pending_mask;
522static cpumask_var_t tick_broadcast_force_mask;
523
524/*
525 * Exposed for debugging: see timer_list.c
526 */
527struct cpumask *tick_get_broadcast_oneshot_mask(void)
528{
529 return tick_broadcast_oneshot_mask;
530}
531
532/*
533 * Called before going idle with interrupts disabled. Checks whether a
534 * broadcast event from the other core is about to happen. We detected
535 * that in tick_broadcast_oneshot_control(). The callsite can use this
536 * to avoid a deep idle transition as we are about to get the
537 * broadcast IPI right away.
538 */
539int tick_check_broadcast_expired(void)
540{
541 return cpumask_test_cpu(smp_processor_id(), tick_broadcast_force_mask);
542}
543
544/*
545 * Set broadcast interrupt affinity
546 */
547static void tick_broadcast_set_affinity(struct clock_event_device *bc,
548 const struct cpumask *cpumask)
549{
550 if (!(bc->features & CLOCK_EVT_FEAT_DYNIRQ))
551 return;
552
553 if (cpumask_equal(bc->cpumask, cpumask))
554 return;
555
556 bc->cpumask = cpumask;
557 irq_set_affinity(bc->irq, bc->cpumask);
558}
559
560static void tick_broadcast_set_event(struct clock_event_device *bc, int cpu,
561 ktime_t expires)
562{
563 if (!clockevent_state_oneshot(bc))
564 clockevents_switch_state(bc, CLOCK_EVT_STATE_ONESHOT);
565
566 clockevents_program_event(bc, expires, 1);
567 tick_broadcast_set_affinity(bc, cpumask_of(cpu));
568}
569
570static void tick_resume_broadcast_oneshot(struct clock_event_device *bc)
571{
572 clockevents_switch_state(bc, CLOCK_EVT_STATE_ONESHOT);
573}
574
575/*
576 * Called from irq_enter() when idle was interrupted to reenable the
577 * per cpu device.
578 */
579void tick_check_oneshot_broadcast_this_cpu(void)
580{
581 if (cpumask_test_cpu(smp_processor_id(), tick_broadcast_oneshot_mask)) {
582 struct tick_device *td = this_cpu_ptr(&tick_cpu_device);
583
584 /*
585 * We might be in the middle of switching over from
586 * periodic to oneshot. If the CPU has not yet
587 * switched over, leave the device alone.
588 */
589 if (td->mode == TICKDEV_MODE_ONESHOT) {
590 clockevents_switch_state(td->evtdev,
591 CLOCK_EVT_STATE_ONESHOT);
592 }
593 }
594}
595
596/*
597 * Handle oneshot mode broadcasting
598 */
599static void tick_handle_oneshot_broadcast(struct clock_event_device *dev)
600{
601 struct tick_device *td;
602 ktime_t now, next_event;
603 int cpu, next_cpu = 0;
604 bool bc_local;
605
606 raw_spin_lock(&tick_broadcast_lock);
607 dev->next_event.tv64 = KTIME_MAX;
608 next_event.tv64 = KTIME_MAX;
609 cpumask_clear(tmpmask);
610 now = ktime_get();
611 /* Find all expired events */
612 for_each_cpu(cpu, tick_broadcast_oneshot_mask) {
613 td = &per_cpu(tick_cpu_device, cpu);
614 if (td->evtdev->next_event.tv64 <= now.tv64) {
615 cpumask_set_cpu(cpu, tmpmask);
616 /*
617 * Mark the remote cpu in the pending mask, so
618 * it can avoid reprogramming the cpu local
619 * timer in tick_broadcast_oneshot_control().
620 */
621 cpumask_set_cpu(cpu, tick_broadcast_pending_mask);
622 } else if (td->evtdev->next_event.tv64 < next_event.tv64) {
623 next_event.tv64 = td->evtdev->next_event.tv64;
624 next_cpu = cpu;
625 }
626 }
627
628 /*
629 * Remove the current cpu from the pending mask. The event is
630 * delivered immediately in tick_do_broadcast() !
631 */
632 cpumask_clear_cpu(smp_processor_id(), tick_broadcast_pending_mask);
633
634 /* Take care of enforced broadcast requests */
635 cpumask_or(tmpmask, tmpmask, tick_broadcast_force_mask);
636 cpumask_clear(tick_broadcast_force_mask);
637
638 /*
639 * Sanity check. Catch the case where we try to broadcast to
640 * offline cpus.
641 */
642 if (WARN_ON_ONCE(!cpumask_subset(tmpmask, cpu_online_mask)))
643 cpumask_and(tmpmask, tmpmask, cpu_online_mask);
644
645 /*
646 * Wakeup the cpus which have an expired event.
647 */
648 bc_local = tick_do_broadcast(tmpmask);
649
650 /*
651 * Two reasons for reprogram:
652 *
653 * - The global event did not expire any CPU local
654 * events. This happens in dyntick mode, as the maximum PIT
655 * delta is quite small.
656 *
657 * - There are pending events on sleeping CPUs which were not
658 * in the event mask
659 */
660 if (next_event.tv64 != KTIME_MAX)
661 tick_broadcast_set_event(dev, next_cpu, next_event);
662
663 raw_spin_unlock(&tick_broadcast_lock);
664
665 if (bc_local) {
666 td = this_cpu_ptr(&tick_cpu_device);
667 td->evtdev->event_handler(td->evtdev);
668 }
669}
670
671static int broadcast_needs_cpu(struct clock_event_device *bc, int cpu)
672{
673 if (!(bc->features & CLOCK_EVT_FEAT_HRTIMER))
674 return 0;
675 if (bc->next_event.tv64 == KTIME_MAX)
676 return 0;
677 return bc->bound_on == cpu ? -EBUSY : 0;
678}
679
680static void broadcast_shutdown_local(struct clock_event_device *bc,
681 struct clock_event_device *dev)
682{
683 /*
684 * For hrtimer based broadcasting we cannot shutdown the cpu
685 * local device if our own event is the first one to expire or
686 * if we own the broadcast timer.
687 */
688 if (bc->features & CLOCK_EVT_FEAT_HRTIMER) {
689 if (broadcast_needs_cpu(bc, smp_processor_id()))
690 return;
691 if (dev->next_event.tv64 < bc->next_event.tv64)
692 return;
693 }
694 clockevents_switch_state(dev, CLOCK_EVT_STATE_SHUTDOWN);
695}
696
697int __tick_broadcast_oneshot_control(enum tick_broadcast_state state)
698{
699 struct clock_event_device *bc, *dev;
700 int cpu, ret = 0;
701 ktime_t now;
702
703 /*
704 * If there is no broadcast device, tell the caller not to go
705 * into deep idle.
706 */
707 if (!tick_broadcast_device.evtdev)
708 return -EBUSY;
709
710 dev = this_cpu_ptr(&tick_cpu_device)->evtdev;
711
712 raw_spin_lock(&tick_broadcast_lock);
713 bc = tick_broadcast_device.evtdev;
714 cpu = smp_processor_id();
715
716 if (state == TICK_BROADCAST_ENTER) {
717 /*
718 * If the current CPU owns the hrtimer broadcast
719 * mechanism, it cannot go deep idle and we do not add
720 * the CPU to the broadcast mask. We don't have to go
721 * through the EXIT path as the local timer is not
722 * shutdown.
723 */
724 ret = broadcast_needs_cpu(bc, cpu);
725 if (ret)
726 goto out;
727
728 /*
729 * If the broadcast device is in periodic mode, we
730 * return.
731 */
732 if (tick_broadcast_device.mode == TICKDEV_MODE_PERIODIC) {
733 /* If it is a hrtimer based broadcast, return busy */
734 if (bc->features & CLOCK_EVT_FEAT_HRTIMER)
735 ret = -EBUSY;
736 goto out;
737 }
738
739 if (!cpumask_test_and_set_cpu(cpu, tick_broadcast_oneshot_mask)) {
740 WARN_ON_ONCE(cpumask_test_cpu(cpu, tick_broadcast_pending_mask));
741
742 /* Conditionally shut down the local timer. */
743 broadcast_shutdown_local(bc, dev);
744
745 /*
746 * We only reprogram the broadcast timer if we
747 * did not mark ourself in the force mask and
748 * if the cpu local event is earlier than the
749 * broadcast event. If the current CPU is in
750 * the force mask, then we are going to be
751 * woken by the IPI right away; we return
752 * busy, so the CPU does not try to go deep
753 * idle.
754 */
755 if (cpumask_test_cpu(cpu, tick_broadcast_force_mask)) {
756 ret = -EBUSY;
757 } else if (dev->next_event.tv64 < bc->next_event.tv64) {
758 tick_broadcast_set_event(bc, cpu, dev->next_event);
759 /*
760 * In case of hrtimer broadcasts the
761 * programming might have moved the
762 * timer to this cpu. If yes, remove
763 * us from the broadcast mask and
764 * return busy.
765 */
766 ret = broadcast_needs_cpu(bc, cpu);
767 if (ret) {
768 cpumask_clear_cpu(cpu,
769 tick_broadcast_oneshot_mask);
770 }
771 }
772 }
773 } else {
774 if (cpumask_test_and_clear_cpu(cpu, tick_broadcast_oneshot_mask)) {
775 clockevents_switch_state(dev, CLOCK_EVT_STATE_ONESHOT);
776 /*
777 * The cpu which was handling the broadcast
778 * timer marked this cpu in the broadcast
779 * pending mask and fired the broadcast
780 * IPI. So we are going to handle the expired
781 * event anyway via the broadcast IPI
782 * handler. No need to reprogram the timer
783 * with an already expired event.
784 */
785 if (cpumask_test_and_clear_cpu(cpu,
786 tick_broadcast_pending_mask))
787 goto out;
788
789 /*
790 * Bail out if there is no next event.
791 */
792 if (dev->next_event.tv64 == KTIME_MAX)
793 goto out;
794 /*
795 * If the pending bit is not set, then we are
796 * either the CPU handling the broadcast
797 * interrupt or we got woken by something else.
798 *
799 * We are not longer in the broadcast mask, so
800 * if the cpu local expiry time is already
801 * reached, we would reprogram the cpu local
802 * timer with an already expired event.
803 *
804 * This can lead to a ping-pong when we return
805 * to idle and therefor rearm the broadcast
806 * timer before the cpu local timer was able
807 * to fire. This happens because the forced
808 * reprogramming makes sure that the event
809 * will happen in the future and depending on
810 * the min_delta setting this might be far
811 * enough out that the ping-pong starts.
812 *
813 * If the cpu local next_event has expired
814 * then we know that the broadcast timer
815 * next_event has expired as well and
816 * broadcast is about to be handled. So we
817 * avoid reprogramming and enforce that the
818 * broadcast handler, which did not run yet,
819 * will invoke the cpu local handler.
820 *
821 * We cannot call the handler directly from
822 * here, because we might be in a NOHZ phase
823 * and we did not go through the irq_enter()
824 * nohz fixups.
825 */
826 now = ktime_get();
827 if (dev->next_event.tv64 <= now.tv64) {
828 cpumask_set_cpu(cpu, tick_broadcast_force_mask);
829 goto out;
830 }
831 /*
832 * We got woken by something else. Reprogram
833 * the cpu local timer device.
834 */
835 tick_program_event(dev->next_event, 1);
836 }
837 }
838out:
839 raw_spin_unlock(&tick_broadcast_lock);
840 return ret;
841}
842
843/*
844 * Reset the one shot broadcast for a cpu
845 *
846 * Called with tick_broadcast_lock held
847 */
848static void tick_broadcast_clear_oneshot(int cpu)
849{
850 cpumask_clear_cpu(cpu, tick_broadcast_oneshot_mask);
851 cpumask_clear_cpu(cpu, tick_broadcast_pending_mask);
852}
853
854static void tick_broadcast_init_next_event(struct cpumask *mask,
855 ktime_t expires)
856{
857 struct tick_device *td;
858 int cpu;
859
860 for_each_cpu(cpu, mask) {
861 td = &per_cpu(tick_cpu_device, cpu);
862 if (td->evtdev)
863 td->evtdev->next_event = expires;
864 }
865}
866
867/**
868 * tick_broadcast_setup_oneshot - setup the broadcast device
869 */
870void tick_broadcast_setup_oneshot(struct clock_event_device *bc)
871{
872 int cpu = smp_processor_id();
873
874 /* Set it up only once ! */
875 if (bc->event_handler != tick_handle_oneshot_broadcast) {
876 int was_periodic = clockevent_state_periodic(bc);
877
878 bc->event_handler = tick_handle_oneshot_broadcast;
879
880 /*
881 * We must be careful here. There might be other CPUs
882 * waiting for periodic broadcast. We need to set the
883 * oneshot_mask bits for those and program the
884 * broadcast device to fire.
885 */
886 cpumask_copy(tmpmask, tick_broadcast_mask);
887 cpumask_clear_cpu(cpu, tmpmask);
888 cpumask_or(tick_broadcast_oneshot_mask,
889 tick_broadcast_oneshot_mask, tmpmask);
890
891 if (was_periodic && !cpumask_empty(tmpmask)) {
892 clockevents_switch_state(bc, CLOCK_EVT_STATE_ONESHOT);
893 tick_broadcast_init_next_event(tmpmask,
894 tick_next_period);
895 tick_broadcast_set_event(bc, cpu, tick_next_period);
896 } else
897 bc->next_event.tv64 = KTIME_MAX;
898 } else {
899 /*
900 * The first cpu which switches to oneshot mode sets
901 * the bit for all other cpus which are in the general
902 * (periodic) broadcast mask. So the bit is set and
903 * would prevent the first broadcast enter after this
904 * to program the bc device.
905 */
906 tick_broadcast_clear_oneshot(cpu);
907 }
908}
909
910/*
911 * Select oneshot operating mode for the broadcast device
912 */
913void tick_broadcast_switch_to_oneshot(void)
914{
915 struct clock_event_device *bc;
916 unsigned long flags;
917
918 raw_spin_lock_irqsave(&tick_broadcast_lock, flags);
919
920 tick_broadcast_device.mode = TICKDEV_MODE_ONESHOT;
921 bc = tick_broadcast_device.evtdev;
922 if (bc)
923 tick_broadcast_setup_oneshot(bc);
924
925 raw_spin_unlock_irqrestore(&tick_broadcast_lock, flags);
926}
927
928#ifdef CONFIG_HOTPLUG_CPU
929void hotplug_cpu__broadcast_tick_pull(int deadcpu)
930{
931 struct clock_event_device *bc;
932 unsigned long flags;
933
934 raw_spin_lock_irqsave(&tick_broadcast_lock, flags);
935 bc = tick_broadcast_device.evtdev;
936
937 if (bc && broadcast_needs_cpu(bc, deadcpu)) {
938 /* This moves the broadcast assignment to this CPU: */
939 clockevents_program_event(bc, bc->next_event, 1);
940 }
941 raw_spin_unlock_irqrestore(&tick_broadcast_lock, flags);
942}
943
944/*
945 * Remove a dead CPU from broadcasting
946 */
947void tick_shutdown_broadcast_oneshot(unsigned int cpu)
948{
949 unsigned long flags;
950
951 raw_spin_lock_irqsave(&tick_broadcast_lock, flags);
952
953 /*
954 * Clear the broadcast masks for the dead cpu, but do not stop
955 * the broadcast device!
956 */
957 cpumask_clear_cpu(cpu, tick_broadcast_oneshot_mask);
958 cpumask_clear_cpu(cpu, tick_broadcast_pending_mask);
959 cpumask_clear_cpu(cpu, tick_broadcast_force_mask);
960
961 raw_spin_unlock_irqrestore(&tick_broadcast_lock, flags);
962}
963#endif
964
965/*
966 * Check, whether the broadcast device is in one shot mode
967 */
968int tick_broadcast_oneshot_active(void)
969{
970 return tick_broadcast_device.mode == TICKDEV_MODE_ONESHOT;
971}
972
973/*
974 * Check whether the broadcast device supports oneshot.
975 */
976bool tick_broadcast_oneshot_available(void)
977{
978 struct clock_event_device *bc = tick_broadcast_device.evtdev;
979
980 return bc ? bc->features & CLOCK_EVT_FEAT_ONESHOT : false;
981}
982
983#else
984int __tick_broadcast_oneshot_control(enum tick_broadcast_state state)
985{
986 struct clock_event_device *bc = tick_broadcast_device.evtdev;
987
988 if (!bc || (bc->features & CLOCK_EVT_FEAT_HRTIMER))
989 return -EBUSY;
990
991 return 0;
992}
993#endif
994
995void __init tick_broadcast_init(void)
996{
997 zalloc_cpumask_var(&tick_broadcast_mask, GFP_NOWAIT);
998 zalloc_cpumask_var(&tick_broadcast_on, GFP_NOWAIT);
999 zalloc_cpumask_var(&tmpmask, GFP_NOWAIT);
1000#ifdef CONFIG_TICK_ONESHOT
1001 zalloc_cpumask_var(&tick_broadcast_oneshot_mask, GFP_NOWAIT);
1002 zalloc_cpumask_var(&tick_broadcast_pending_mask, GFP_NOWAIT);
1003 zalloc_cpumask_var(&tick_broadcast_force_mask, GFP_NOWAIT);
1004#endif
1005}
1// SPDX-License-Identifier: GPL-2.0
2/*
3 * This file contains functions which emulate a local clock-event
4 * device via a broadcast event source.
5 *
6 * Copyright(C) 2005-2006, Thomas Gleixner <tglx@linutronix.de>
7 * Copyright(C) 2005-2007, Red Hat, Inc., Ingo Molnar
8 * Copyright(C) 2006-2007, Timesys Corp., Thomas Gleixner
9 */
10#include <linux/cpu.h>
11#include <linux/err.h>
12#include <linux/hrtimer.h>
13#include <linux/interrupt.h>
14#include <linux/percpu.h>
15#include <linux/profile.h>
16#include <linux/sched.h>
17#include <linux/smp.h>
18#include <linux/module.h>
19
20#include "tick-internal.h"
21
22/*
23 * Broadcast support for broken x86 hardware, where the local apic
24 * timer stops in C3 state.
25 */
26
27static struct tick_device tick_broadcast_device;
28static cpumask_var_t tick_broadcast_mask __cpumask_var_read_mostly;
29static cpumask_var_t tick_broadcast_on __cpumask_var_read_mostly;
30static cpumask_var_t tmpmask __cpumask_var_read_mostly;
31static int tick_broadcast_forced;
32
33static __cacheline_aligned_in_smp DEFINE_RAW_SPINLOCK(tick_broadcast_lock);
34
35#ifdef CONFIG_TICK_ONESHOT
36static DEFINE_PER_CPU(struct clock_event_device *, tick_oneshot_wakeup_device);
37
38static void tick_broadcast_setup_oneshot(struct clock_event_device *bc, bool from_periodic);
39static void tick_broadcast_clear_oneshot(int cpu);
40static void tick_resume_broadcast_oneshot(struct clock_event_device *bc);
41# ifdef CONFIG_HOTPLUG_CPU
42static void tick_broadcast_oneshot_offline(unsigned int cpu);
43# endif
44#else
45static inline void
46tick_broadcast_setup_oneshot(struct clock_event_device *bc, bool from_periodic) { BUG(); }
47static inline void tick_broadcast_clear_oneshot(int cpu) { }
48static inline void tick_resume_broadcast_oneshot(struct clock_event_device *bc) { }
49# ifdef CONFIG_HOTPLUG_CPU
50static inline void tick_broadcast_oneshot_offline(unsigned int cpu) { }
51# endif
52#endif
53
54/*
55 * Debugging: see timer_list.c
56 */
57struct tick_device *tick_get_broadcast_device(void)
58{
59 return &tick_broadcast_device;
60}
61
62struct cpumask *tick_get_broadcast_mask(void)
63{
64 return tick_broadcast_mask;
65}
66
67static struct clock_event_device *tick_get_oneshot_wakeup_device(int cpu);
68
69const struct clock_event_device *tick_get_wakeup_device(int cpu)
70{
71 return tick_get_oneshot_wakeup_device(cpu);
72}
73
74/*
75 * Start the device in periodic mode
76 */
77static void tick_broadcast_start_periodic(struct clock_event_device *bc)
78{
79 if (bc)
80 tick_setup_periodic(bc, 1);
81}
82
83/*
84 * Check, if the device can be utilized as broadcast device:
85 */
86static bool tick_check_broadcast_device(struct clock_event_device *curdev,
87 struct clock_event_device *newdev)
88{
89 if ((newdev->features & CLOCK_EVT_FEAT_DUMMY) ||
90 (newdev->features & CLOCK_EVT_FEAT_PERCPU) ||
91 (newdev->features & CLOCK_EVT_FEAT_C3STOP))
92 return false;
93
94 if (tick_broadcast_device.mode == TICKDEV_MODE_ONESHOT &&
95 !(newdev->features & CLOCK_EVT_FEAT_ONESHOT))
96 return false;
97
98 return !curdev || newdev->rating > curdev->rating;
99}
100
101#ifdef CONFIG_TICK_ONESHOT
102static struct clock_event_device *tick_get_oneshot_wakeup_device(int cpu)
103{
104 return per_cpu(tick_oneshot_wakeup_device, cpu);
105}
106
107static void tick_oneshot_wakeup_handler(struct clock_event_device *wd)
108{
109 /*
110 * If we woke up early and the tick was reprogrammed in the
111 * meantime then this may be spurious but harmless.
112 */
113 tick_receive_broadcast();
114}
115
116static bool tick_set_oneshot_wakeup_device(struct clock_event_device *newdev,
117 int cpu)
118{
119 struct clock_event_device *curdev = tick_get_oneshot_wakeup_device(cpu);
120
121 if (!newdev)
122 goto set_device;
123
124 if ((newdev->features & CLOCK_EVT_FEAT_DUMMY) ||
125 (newdev->features & CLOCK_EVT_FEAT_C3STOP))
126 return false;
127
128 if (!(newdev->features & CLOCK_EVT_FEAT_PERCPU) ||
129 !(newdev->features & CLOCK_EVT_FEAT_ONESHOT))
130 return false;
131
132 if (!cpumask_equal(newdev->cpumask, cpumask_of(cpu)))
133 return false;
134
135 if (curdev && newdev->rating <= curdev->rating)
136 return false;
137
138 if (!try_module_get(newdev->owner))
139 return false;
140
141 newdev->event_handler = tick_oneshot_wakeup_handler;
142set_device:
143 clockevents_exchange_device(curdev, newdev);
144 per_cpu(tick_oneshot_wakeup_device, cpu) = newdev;
145 return true;
146}
147#else
148static struct clock_event_device *tick_get_oneshot_wakeup_device(int cpu)
149{
150 return NULL;
151}
152
153static bool tick_set_oneshot_wakeup_device(struct clock_event_device *newdev,
154 int cpu)
155{
156 return false;
157}
158#endif
159
160/*
161 * Conditionally install/replace broadcast device
162 */
163void tick_install_broadcast_device(struct clock_event_device *dev, int cpu)
164{
165 struct clock_event_device *cur = tick_broadcast_device.evtdev;
166
167 if (tick_set_oneshot_wakeup_device(dev, cpu))
168 return;
169
170 if (!tick_check_broadcast_device(cur, dev))
171 return;
172
173 if (!try_module_get(dev->owner))
174 return;
175
176 clockevents_exchange_device(cur, dev);
177 if (cur)
178 cur->event_handler = clockevents_handle_noop;
179 tick_broadcast_device.evtdev = dev;
180 if (!cpumask_empty(tick_broadcast_mask))
181 tick_broadcast_start_periodic(dev);
182
183 if (!(dev->features & CLOCK_EVT_FEAT_ONESHOT))
184 return;
185
186 /*
187 * If the system already runs in oneshot mode, switch the newly
188 * registered broadcast device to oneshot mode explicitly.
189 */
190 if (tick_broadcast_oneshot_active()) {
191 tick_broadcast_switch_to_oneshot();
192 return;
193 }
194
195 /*
196 * Inform all cpus about this. We might be in a situation
197 * where we did not switch to oneshot mode because the per cpu
198 * devices are affected by CLOCK_EVT_FEAT_C3STOP and the lack
199 * of a oneshot capable broadcast device. Without that
200 * notification the systems stays stuck in periodic mode
201 * forever.
202 */
203 tick_clock_notify();
204}
205
206/*
207 * Check, if the device is the broadcast device
208 */
209int tick_is_broadcast_device(struct clock_event_device *dev)
210{
211 return (dev && tick_broadcast_device.evtdev == dev);
212}
213
214int tick_broadcast_update_freq(struct clock_event_device *dev, u32 freq)
215{
216 int ret = -ENODEV;
217
218 if (tick_is_broadcast_device(dev)) {
219 raw_spin_lock(&tick_broadcast_lock);
220 ret = __clockevents_update_freq(dev, freq);
221 raw_spin_unlock(&tick_broadcast_lock);
222 }
223 return ret;
224}
225
226
227static void err_broadcast(const struct cpumask *mask)
228{
229 pr_crit_once("Failed to broadcast timer tick. Some CPUs may be unresponsive.\n");
230}
231
232static void tick_device_setup_broadcast_func(struct clock_event_device *dev)
233{
234 if (!dev->broadcast)
235 dev->broadcast = tick_broadcast;
236 if (!dev->broadcast) {
237 pr_warn_once("%s depends on broadcast, but no broadcast function available\n",
238 dev->name);
239 dev->broadcast = err_broadcast;
240 }
241}
242
243/*
244 * Check, if the device is dysfunctional and a placeholder, which
245 * needs to be handled by the broadcast device.
246 */
247int tick_device_uses_broadcast(struct clock_event_device *dev, int cpu)
248{
249 struct clock_event_device *bc = tick_broadcast_device.evtdev;
250 unsigned long flags;
251 int ret = 0;
252
253 raw_spin_lock_irqsave(&tick_broadcast_lock, flags);
254
255 /*
256 * Devices might be registered with both periodic and oneshot
257 * mode disabled. This signals, that the device needs to be
258 * operated from the broadcast device and is a placeholder for
259 * the cpu local device.
260 */
261 if (!tick_device_is_functional(dev)) {
262 dev->event_handler = tick_handle_periodic;
263 tick_device_setup_broadcast_func(dev);
264 cpumask_set_cpu(cpu, tick_broadcast_mask);
265 if (tick_broadcast_device.mode == TICKDEV_MODE_PERIODIC)
266 tick_broadcast_start_periodic(bc);
267 else
268 tick_broadcast_setup_oneshot(bc, false);
269 ret = 1;
270 } else {
271 /*
272 * Clear the broadcast bit for this cpu if the
273 * device is not power state affected.
274 */
275 if (!(dev->features & CLOCK_EVT_FEAT_C3STOP))
276 cpumask_clear_cpu(cpu, tick_broadcast_mask);
277 else
278 tick_device_setup_broadcast_func(dev);
279
280 /*
281 * Clear the broadcast bit if the CPU is not in
282 * periodic broadcast on state.
283 */
284 if (!cpumask_test_cpu(cpu, tick_broadcast_on))
285 cpumask_clear_cpu(cpu, tick_broadcast_mask);
286
287 switch (tick_broadcast_device.mode) {
288 case TICKDEV_MODE_ONESHOT:
289 /*
290 * If the system is in oneshot mode we can
291 * unconditionally clear the oneshot mask bit,
292 * because the CPU is running and therefore
293 * not in an idle state which causes the power
294 * state affected device to stop. Let the
295 * caller initialize the device.
296 */
297 tick_broadcast_clear_oneshot(cpu);
298 ret = 0;
299 break;
300
301 case TICKDEV_MODE_PERIODIC:
302 /*
303 * If the system is in periodic mode, check
304 * whether the broadcast device can be
305 * switched off now.
306 */
307 if (cpumask_empty(tick_broadcast_mask) && bc)
308 clockevents_shutdown(bc);
309 /*
310 * If we kept the cpu in the broadcast mask,
311 * tell the caller to leave the per cpu device
312 * in shutdown state. The periodic interrupt
313 * is delivered by the broadcast device, if
314 * the broadcast device exists and is not
315 * hrtimer based.
316 */
317 if (bc && !(bc->features & CLOCK_EVT_FEAT_HRTIMER))
318 ret = cpumask_test_cpu(cpu, tick_broadcast_mask);
319 break;
320 default:
321 break;
322 }
323 }
324 raw_spin_unlock_irqrestore(&tick_broadcast_lock, flags);
325 return ret;
326}
327
328int tick_receive_broadcast(void)
329{
330 struct tick_device *td = this_cpu_ptr(&tick_cpu_device);
331 struct clock_event_device *evt = td->evtdev;
332
333 if (!evt)
334 return -ENODEV;
335
336 if (!evt->event_handler)
337 return -EINVAL;
338
339 evt->event_handler(evt);
340 return 0;
341}
342
343/*
344 * Broadcast the event to the cpus, which are set in the mask (mangled).
345 */
346static bool tick_do_broadcast(struct cpumask *mask)
347{
348 int cpu = smp_processor_id();
349 struct tick_device *td;
350 bool local = false;
351
352 /*
353 * Check, if the current cpu is in the mask
354 */
355 if (cpumask_test_cpu(cpu, mask)) {
356 struct clock_event_device *bc = tick_broadcast_device.evtdev;
357
358 cpumask_clear_cpu(cpu, mask);
359 /*
360 * We only run the local handler, if the broadcast
361 * device is not hrtimer based. Otherwise we run into
362 * a hrtimer recursion.
363 *
364 * local timer_interrupt()
365 * local_handler()
366 * expire_hrtimers()
367 * bc_handler()
368 * local_handler()
369 * expire_hrtimers()
370 */
371 local = !(bc->features & CLOCK_EVT_FEAT_HRTIMER);
372 }
373
374 if (!cpumask_empty(mask)) {
375 /*
376 * It might be necessary to actually check whether the devices
377 * have different broadcast functions. For now, just use the
378 * one of the first device. This works as long as we have this
379 * misfeature only on x86 (lapic)
380 */
381 td = &per_cpu(tick_cpu_device, cpumask_first(mask));
382 td->evtdev->broadcast(mask);
383 }
384 return local;
385}
386
387/*
388 * Periodic broadcast:
389 * - invoke the broadcast handlers
390 */
391static bool tick_do_periodic_broadcast(void)
392{
393 cpumask_and(tmpmask, cpu_online_mask, tick_broadcast_mask);
394 return tick_do_broadcast(tmpmask);
395}
396
397/*
398 * Event handler for periodic broadcast ticks
399 */
400static void tick_handle_periodic_broadcast(struct clock_event_device *dev)
401{
402 struct tick_device *td = this_cpu_ptr(&tick_cpu_device);
403 bool bc_local;
404
405 raw_spin_lock(&tick_broadcast_lock);
406
407 /* Handle spurious interrupts gracefully */
408 if (clockevent_state_shutdown(tick_broadcast_device.evtdev)) {
409 raw_spin_unlock(&tick_broadcast_lock);
410 return;
411 }
412
413 bc_local = tick_do_periodic_broadcast();
414
415 if (clockevent_state_oneshot(dev)) {
416 ktime_t next = ktime_add_ns(dev->next_event, TICK_NSEC);
417
418 clockevents_program_event(dev, next, true);
419 }
420 raw_spin_unlock(&tick_broadcast_lock);
421
422 /*
423 * We run the handler of the local cpu after dropping
424 * tick_broadcast_lock because the handler might deadlock when
425 * trying to switch to oneshot mode.
426 */
427 if (bc_local)
428 td->evtdev->event_handler(td->evtdev);
429}
430
431/**
432 * tick_broadcast_control - Enable/disable or force broadcast mode
433 * @mode: The selected broadcast mode
434 *
435 * Called when the system enters a state where affected tick devices
436 * might stop. Note: TICK_BROADCAST_FORCE cannot be undone.
437 */
438void tick_broadcast_control(enum tick_broadcast_mode mode)
439{
440 struct clock_event_device *bc, *dev;
441 struct tick_device *td;
442 int cpu, bc_stopped;
443 unsigned long flags;
444
445 /* Protects also the local clockevent device. */
446 raw_spin_lock_irqsave(&tick_broadcast_lock, flags);
447 td = this_cpu_ptr(&tick_cpu_device);
448 dev = td->evtdev;
449
450 /*
451 * Is the device not affected by the powerstate ?
452 */
453 if (!dev || !(dev->features & CLOCK_EVT_FEAT_C3STOP))
454 goto out;
455
456 if (!tick_device_is_functional(dev))
457 goto out;
458
459 cpu = smp_processor_id();
460 bc = tick_broadcast_device.evtdev;
461 bc_stopped = cpumask_empty(tick_broadcast_mask);
462
463 switch (mode) {
464 case TICK_BROADCAST_FORCE:
465 tick_broadcast_forced = 1;
466 fallthrough;
467 case TICK_BROADCAST_ON:
468 cpumask_set_cpu(cpu, tick_broadcast_on);
469 if (!cpumask_test_and_set_cpu(cpu, tick_broadcast_mask)) {
470 /*
471 * Only shutdown the cpu local device, if:
472 *
473 * - the broadcast device exists
474 * - the broadcast device is not a hrtimer based one
475 * - the broadcast device is in periodic mode to
476 * avoid a hiccup during switch to oneshot mode
477 */
478 if (bc && !(bc->features & CLOCK_EVT_FEAT_HRTIMER) &&
479 tick_broadcast_device.mode == TICKDEV_MODE_PERIODIC)
480 clockevents_shutdown(dev);
481 }
482 break;
483
484 case TICK_BROADCAST_OFF:
485 if (tick_broadcast_forced)
486 break;
487 cpumask_clear_cpu(cpu, tick_broadcast_on);
488 if (cpumask_test_and_clear_cpu(cpu, tick_broadcast_mask)) {
489 if (tick_broadcast_device.mode ==
490 TICKDEV_MODE_PERIODIC)
491 tick_setup_periodic(dev, 0);
492 }
493 break;
494 }
495
496 if (bc) {
497 if (cpumask_empty(tick_broadcast_mask)) {
498 if (!bc_stopped)
499 clockevents_shutdown(bc);
500 } else if (bc_stopped) {
501 if (tick_broadcast_device.mode == TICKDEV_MODE_PERIODIC)
502 tick_broadcast_start_periodic(bc);
503 else
504 tick_broadcast_setup_oneshot(bc, false);
505 }
506 }
507out:
508 raw_spin_unlock_irqrestore(&tick_broadcast_lock, flags);
509}
510EXPORT_SYMBOL_GPL(tick_broadcast_control);
511
512/*
513 * Set the periodic handler depending on broadcast on/off
514 */
515void tick_set_periodic_handler(struct clock_event_device *dev, int broadcast)
516{
517 if (!broadcast)
518 dev->event_handler = tick_handle_periodic;
519 else
520 dev->event_handler = tick_handle_periodic_broadcast;
521}
522
523#ifdef CONFIG_HOTPLUG_CPU
524static void tick_shutdown_broadcast(void)
525{
526 struct clock_event_device *bc = tick_broadcast_device.evtdev;
527
528 if (tick_broadcast_device.mode == TICKDEV_MODE_PERIODIC) {
529 if (bc && cpumask_empty(tick_broadcast_mask))
530 clockevents_shutdown(bc);
531 }
532}
533
534/*
535 * Remove a CPU from broadcasting
536 */
537void tick_broadcast_offline(unsigned int cpu)
538{
539 raw_spin_lock(&tick_broadcast_lock);
540 cpumask_clear_cpu(cpu, tick_broadcast_mask);
541 cpumask_clear_cpu(cpu, tick_broadcast_on);
542 tick_broadcast_oneshot_offline(cpu);
543 tick_shutdown_broadcast();
544 raw_spin_unlock(&tick_broadcast_lock);
545}
546
547#endif
548
549void tick_suspend_broadcast(void)
550{
551 struct clock_event_device *bc;
552 unsigned long flags;
553
554 raw_spin_lock_irqsave(&tick_broadcast_lock, flags);
555
556 bc = tick_broadcast_device.evtdev;
557 if (bc)
558 clockevents_shutdown(bc);
559
560 raw_spin_unlock_irqrestore(&tick_broadcast_lock, flags);
561}
562
563/*
564 * This is called from tick_resume_local() on a resuming CPU. That's
565 * called from the core resume function, tick_unfreeze() and the magic XEN
566 * resume hackery.
567 *
568 * In none of these cases the broadcast device mode can change and the
569 * bit of the resuming CPU in the broadcast mask is safe as well.
570 */
571bool tick_resume_check_broadcast(void)
572{
573 if (tick_broadcast_device.mode == TICKDEV_MODE_ONESHOT)
574 return false;
575 else
576 return cpumask_test_cpu(smp_processor_id(), tick_broadcast_mask);
577}
578
579void tick_resume_broadcast(void)
580{
581 struct clock_event_device *bc;
582 unsigned long flags;
583
584 raw_spin_lock_irqsave(&tick_broadcast_lock, flags);
585
586 bc = tick_broadcast_device.evtdev;
587
588 if (bc) {
589 clockevents_tick_resume(bc);
590
591 switch (tick_broadcast_device.mode) {
592 case TICKDEV_MODE_PERIODIC:
593 if (!cpumask_empty(tick_broadcast_mask))
594 tick_broadcast_start_periodic(bc);
595 break;
596 case TICKDEV_MODE_ONESHOT:
597 if (!cpumask_empty(tick_broadcast_mask))
598 tick_resume_broadcast_oneshot(bc);
599 break;
600 }
601 }
602 raw_spin_unlock_irqrestore(&tick_broadcast_lock, flags);
603}
604
605#ifdef CONFIG_TICK_ONESHOT
606
607static cpumask_var_t tick_broadcast_oneshot_mask __cpumask_var_read_mostly;
608static cpumask_var_t tick_broadcast_pending_mask __cpumask_var_read_mostly;
609static cpumask_var_t tick_broadcast_force_mask __cpumask_var_read_mostly;
610
611/*
612 * Exposed for debugging: see timer_list.c
613 */
614struct cpumask *tick_get_broadcast_oneshot_mask(void)
615{
616 return tick_broadcast_oneshot_mask;
617}
618
619/*
620 * Called before going idle with interrupts disabled. Checks whether a
621 * broadcast event from the other core is about to happen. We detected
622 * that in tick_broadcast_oneshot_control(). The callsite can use this
623 * to avoid a deep idle transition as we are about to get the
624 * broadcast IPI right away.
625 */
626noinstr int tick_check_broadcast_expired(void)
627{
628#ifdef _ASM_GENERIC_BITOPS_INSTRUMENTED_NON_ATOMIC_H
629 return arch_test_bit(smp_processor_id(), cpumask_bits(tick_broadcast_force_mask));
630#else
631 return cpumask_test_cpu(smp_processor_id(), tick_broadcast_force_mask);
632#endif
633}
634
635/*
636 * Set broadcast interrupt affinity
637 */
638static void tick_broadcast_set_affinity(struct clock_event_device *bc,
639 const struct cpumask *cpumask)
640{
641 if (!(bc->features & CLOCK_EVT_FEAT_DYNIRQ))
642 return;
643
644 if (cpumask_equal(bc->cpumask, cpumask))
645 return;
646
647 bc->cpumask = cpumask;
648 irq_set_affinity(bc->irq, bc->cpumask);
649}
650
651static void tick_broadcast_set_event(struct clock_event_device *bc, int cpu,
652 ktime_t expires)
653{
654 if (!clockevent_state_oneshot(bc))
655 clockevents_switch_state(bc, CLOCK_EVT_STATE_ONESHOT);
656
657 clockevents_program_event(bc, expires, 1);
658 tick_broadcast_set_affinity(bc, cpumask_of(cpu));
659}
660
661static void tick_resume_broadcast_oneshot(struct clock_event_device *bc)
662{
663 clockevents_switch_state(bc, CLOCK_EVT_STATE_ONESHOT);
664}
665
666/*
667 * Called from irq_enter() when idle was interrupted to reenable the
668 * per cpu device.
669 */
670void tick_check_oneshot_broadcast_this_cpu(void)
671{
672 if (cpumask_test_cpu(smp_processor_id(), tick_broadcast_oneshot_mask)) {
673 struct tick_device *td = this_cpu_ptr(&tick_cpu_device);
674
675 /*
676 * We might be in the middle of switching over from
677 * periodic to oneshot. If the CPU has not yet
678 * switched over, leave the device alone.
679 */
680 if (td->mode == TICKDEV_MODE_ONESHOT) {
681 clockevents_switch_state(td->evtdev,
682 CLOCK_EVT_STATE_ONESHOT);
683 }
684 }
685}
686
687/*
688 * Handle oneshot mode broadcasting
689 */
690static void tick_handle_oneshot_broadcast(struct clock_event_device *dev)
691{
692 struct tick_device *td;
693 ktime_t now, next_event;
694 int cpu, next_cpu = 0;
695 bool bc_local;
696
697 raw_spin_lock(&tick_broadcast_lock);
698 dev->next_event = KTIME_MAX;
699 next_event = KTIME_MAX;
700 cpumask_clear(tmpmask);
701 now = ktime_get();
702 /* Find all expired events */
703 for_each_cpu(cpu, tick_broadcast_oneshot_mask) {
704 /*
705 * Required for !SMP because for_each_cpu() reports
706 * unconditionally CPU0 as set on UP kernels.
707 */
708 if (!IS_ENABLED(CONFIG_SMP) &&
709 cpumask_empty(tick_broadcast_oneshot_mask))
710 break;
711
712 td = &per_cpu(tick_cpu_device, cpu);
713 if (td->evtdev->next_event <= now) {
714 cpumask_set_cpu(cpu, tmpmask);
715 /*
716 * Mark the remote cpu in the pending mask, so
717 * it can avoid reprogramming the cpu local
718 * timer in tick_broadcast_oneshot_control().
719 */
720 cpumask_set_cpu(cpu, tick_broadcast_pending_mask);
721 } else if (td->evtdev->next_event < next_event) {
722 next_event = td->evtdev->next_event;
723 next_cpu = cpu;
724 }
725 }
726
727 /*
728 * Remove the current cpu from the pending mask. The event is
729 * delivered immediately in tick_do_broadcast() !
730 */
731 cpumask_clear_cpu(smp_processor_id(), tick_broadcast_pending_mask);
732
733 /* Take care of enforced broadcast requests */
734 cpumask_or(tmpmask, tmpmask, tick_broadcast_force_mask);
735 cpumask_clear(tick_broadcast_force_mask);
736
737 /*
738 * Sanity check. Catch the case where we try to broadcast to
739 * offline cpus.
740 */
741 if (WARN_ON_ONCE(!cpumask_subset(tmpmask, cpu_online_mask)))
742 cpumask_and(tmpmask, tmpmask, cpu_online_mask);
743
744 /*
745 * Wakeup the cpus which have an expired event.
746 */
747 bc_local = tick_do_broadcast(tmpmask);
748
749 /*
750 * Two reasons for reprogram:
751 *
752 * - The global event did not expire any CPU local
753 * events. This happens in dyntick mode, as the maximum PIT
754 * delta is quite small.
755 *
756 * - There are pending events on sleeping CPUs which were not
757 * in the event mask
758 */
759 if (next_event != KTIME_MAX)
760 tick_broadcast_set_event(dev, next_cpu, next_event);
761
762 raw_spin_unlock(&tick_broadcast_lock);
763
764 if (bc_local) {
765 td = this_cpu_ptr(&tick_cpu_device);
766 td->evtdev->event_handler(td->evtdev);
767 }
768}
769
770static int broadcast_needs_cpu(struct clock_event_device *bc, int cpu)
771{
772 if (!(bc->features & CLOCK_EVT_FEAT_HRTIMER))
773 return 0;
774 if (bc->next_event == KTIME_MAX)
775 return 0;
776 return bc->bound_on == cpu ? -EBUSY : 0;
777}
778
779static void broadcast_shutdown_local(struct clock_event_device *bc,
780 struct clock_event_device *dev)
781{
782 /*
783 * For hrtimer based broadcasting we cannot shutdown the cpu
784 * local device if our own event is the first one to expire or
785 * if we own the broadcast timer.
786 */
787 if (bc->features & CLOCK_EVT_FEAT_HRTIMER) {
788 if (broadcast_needs_cpu(bc, smp_processor_id()))
789 return;
790 if (dev->next_event < bc->next_event)
791 return;
792 }
793 clockevents_switch_state(dev, CLOCK_EVT_STATE_SHUTDOWN);
794}
795
796static int ___tick_broadcast_oneshot_control(enum tick_broadcast_state state,
797 struct tick_device *td,
798 int cpu)
799{
800 struct clock_event_device *bc, *dev = td->evtdev;
801 int ret = 0;
802 ktime_t now;
803
804 raw_spin_lock(&tick_broadcast_lock);
805 bc = tick_broadcast_device.evtdev;
806
807 if (state == TICK_BROADCAST_ENTER) {
808 /*
809 * If the current CPU owns the hrtimer broadcast
810 * mechanism, it cannot go deep idle and we do not add
811 * the CPU to the broadcast mask. We don't have to go
812 * through the EXIT path as the local timer is not
813 * shutdown.
814 */
815 ret = broadcast_needs_cpu(bc, cpu);
816 if (ret)
817 goto out;
818
819 /*
820 * If the broadcast device is in periodic mode, we
821 * return.
822 */
823 if (tick_broadcast_device.mode == TICKDEV_MODE_PERIODIC) {
824 /* If it is a hrtimer based broadcast, return busy */
825 if (bc->features & CLOCK_EVT_FEAT_HRTIMER)
826 ret = -EBUSY;
827 goto out;
828 }
829
830 if (!cpumask_test_and_set_cpu(cpu, tick_broadcast_oneshot_mask)) {
831 WARN_ON_ONCE(cpumask_test_cpu(cpu, tick_broadcast_pending_mask));
832
833 /* Conditionally shut down the local timer. */
834 broadcast_shutdown_local(bc, dev);
835
836 /*
837 * We only reprogram the broadcast timer if we
838 * did not mark ourself in the force mask and
839 * if the cpu local event is earlier than the
840 * broadcast event. If the current CPU is in
841 * the force mask, then we are going to be
842 * woken by the IPI right away; we return
843 * busy, so the CPU does not try to go deep
844 * idle.
845 */
846 if (cpumask_test_cpu(cpu, tick_broadcast_force_mask)) {
847 ret = -EBUSY;
848 } else if (dev->next_event < bc->next_event) {
849 tick_broadcast_set_event(bc, cpu, dev->next_event);
850 /*
851 * In case of hrtimer broadcasts the
852 * programming might have moved the
853 * timer to this cpu. If yes, remove
854 * us from the broadcast mask and
855 * return busy.
856 */
857 ret = broadcast_needs_cpu(bc, cpu);
858 if (ret) {
859 cpumask_clear_cpu(cpu,
860 tick_broadcast_oneshot_mask);
861 }
862 }
863 }
864 } else {
865 if (cpumask_test_and_clear_cpu(cpu, tick_broadcast_oneshot_mask)) {
866 clockevents_switch_state(dev, CLOCK_EVT_STATE_ONESHOT);
867 /*
868 * The cpu which was handling the broadcast
869 * timer marked this cpu in the broadcast
870 * pending mask and fired the broadcast
871 * IPI. So we are going to handle the expired
872 * event anyway via the broadcast IPI
873 * handler. No need to reprogram the timer
874 * with an already expired event.
875 */
876 if (cpumask_test_and_clear_cpu(cpu,
877 tick_broadcast_pending_mask))
878 goto out;
879
880 /*
881 * Bail out if there is no next event.
882 */
883 if (dev->next_event == KTIME_MAX)
884 goto out;
885 /*
886 * If the pending bit is not set, then we are
887 * either the CPU handling the broadcast
888 * interrupt or we got woken by something else.
889 *
890 * We are no longer in the broadcast mask, so
891 * if the cpu local expiry time is already
892 * reached, we would reprogram the cpu local
893 * timer with an already expired event.
894 *
895 * This can lead to a ping-pong when we return
896 * to idle and therefore rearm the broadcast
897 * timer before the cpu local timer was able
898 * to fire. This happens because the forced
899 * reprogramming makes sure that the event
900 * will happen in the future and depending on
901 * the min_delta setting this might be far
902 * enough out that the ping-pong starts.
903 *
904 * If the cpu local next_event has expired
905 * then we know that the broadcast timer
906 * next_event has expired as well and
907 * broadcast is about to be handled. So we
908 * avoid reprogramming and enforce that the
909 * broadcast handler, which did not run yet,
910 * will invoke the cpu local handler.
911 *
912 * We cannot call the handler directly from
913 * here, because we might be in a NOHZ phase
914 * and we did not go through the irq_enter()
915 * nohz fixups.
916 */
917 now = ktime_get();
918 if (dev->next_event <= now) {
919 cpumask_set_cpu(cpu, tick_broadcast_force_mask);
920 goto out;
921 }
922 /*
923 * We got woken by something else. Reprogram
924 * the cpu local timer device.
925 */
926 tick_program_event(dev->next_event, 1);
927 }
928 }
929out:
930 raw_spin_unlock(&tick_broadcast_lock);
931 return ret;
932}
933
934static int tick_oneshot_wakeup_control(enum tick_broadcast_state state,
935 struct tick_device *td,
936 int cpu)
937{
938 struct clock_event_device *dev, *wd;
939
940 dev = td->evtdev;
941 if (td->mode != TICKDEV_MODE_ONESHOT)
942 return -EINVAL;
943
944 wd = tick_get_oneshot_wakeup_device(cpu);
945 if (!wd)
946 return -ENODEV;
947
948 switch (state) {
949 case TICK_BROADCAST_ENTER:
950 clockevents_switch_state(dev, CLOCK_EVT_STATE_ONESHOT_STOPPED);
951 clockevents_switch_state(wd, CLOCK_EVT_STATE_ONESHOT);
952 clockevents_program_event(wd, dev->next_event, 1);
953 break;
954 case TICK_BROADCAST_EXIT:
955 /* We may have transitioned to oneshot mode while idle */
956 if (clockevent_get_state(wd) != CLOCK_EVT_STATE_ONESHOT)
957 return -ENODEV;
958 }
959
960 return 0;
961}
962
963int __tick_broadcast_oneshot_control(enum tick_broadcast_state state)
964{
965 struct tick_device *td = this_cpu_ptr(&tick_cpu_device);
966 int cpu = smp_processor_id();
967
968 if (!tick_oneshot_wakeup_control(state, td, cpu))
969 return 0;
970
971 if (tick_broadcast_device.evtdev)
972 return ___tick_broadcast_oneshot_control(state, td, cpu);
973
974 /*
975 * If there is no broadcast or wakeup device, tell the caller not
976 * to go into deep idle.
977 */
978 return -EBUSY;
979}
980
981/*
982 * Reset the one shot broadcast for a cpu
983 *
984 * Called with tick_broadcast_lock held
985 */
986static void tick_broadcast_clear_oneshot(int cpu)
987{
988 cpumask_clear_cpu(cpu, tick_broadcast_oneshot_mask);
989 cpumask_clear_cpu(cpu, tick_broadcast_pending_mask);
990}
991
992static void tick_broadcast_init_next_event(struct cpumask *mask,
993 ktime_t expires)
994{
995 struct tick_device *td;
996 int cpu;
997
998 for_each_cpu(cpu, mask) {
999 td = &per_cpu(tick_cpu_device, cpu);
1000 if (td->evtdev)
1001 td->evtdev->next_event = expires;
1002 }
1003}
1004
1005static inline ktime_t tick_get_next_period(void)
1006{
1007 ktime_t next;
1008
1009 /*
1010 * Protect against concurrent updates (store /load tearing on
1011 * 32bit). It does not matter if the time is already in the
1012 * past. The broadcast device which is about to be programmed will
1013 * fire in any case.
1014 */
1015 raw_spin_lock(&jiffies_lock);
1016 next = tick_next_period;
1017 raw_spin_unlock(&jiffies_lock);
1018 return next;
1019}
1020
1021/**
1022 * tick_broadcast_setup_oneshot - setup the broadcast device
1023 */
1024static void tick_broadcast_setup_oneshot(struct clock_event_device *bc,
1025 bool from_periodic)
1026{
1027 int cpu = smp_processor_id();
1028 ktime_t nexttick = 0;
1029
1030 if (!bc)
1031 return;
1032
1033 /*
1034 * When the broadcast device was switched to oneshot by the first
1035 * CPU handling the NOHZ change, the other CPUs will reach this
1036 * code via hrtimer_run_queues() -> tick_check_oneshot_change()
1037 * too. Set up the broadcast device only once!
1038 */
1039 if (bc->event_handler == tick_handle_oneshot_broadcast) {
1040 /*
1041 * The CPU which switched from periodic to oneshot mode
1042 * set the broadcast oneshot bit for all other CPUs which
1043 * are in the general (periodic) broadcast mask to ensure
1044 * that CPUs which wait for the periodic broadcast are
1045 * woken up.
1046 *
1047 * Clear the bit for the local CPU as the set bit would
1048 * prevent the first tick_broadcast_enter() after this CPU
1049 * switched to oneshot state to program the broadcast
1050 * device.
1051 *
1052 * This code can also be reached via tick_broadcast_control(),
1053 * but this cannot avoid the tick_broadcast_clear_oneshot()
1054 * as that would break the periodic to oneshot transition of
1055 * secondary CPUs. But that's harmless as the below only
1056 * clears already cleared bits.
1057 */
1058 tick_broadcast_clear_oneshot(cpu);
1059 return;
1060 }
1061
1062
1063 bc->event_handler = tick_handle_oneshot_broadcast;
1064 bc->next_event = KTIME_MAX;
1065
1066 /*
1067 * When the tick mode is switched from periodic to oneshot it must
1068 * be ensured that CPUs which are waiting for periodic broadcast
1069 * get their wake-up at the next tick. This is achieved by ORing
1070 * tick_broadcast_mask into tick_broadcast_oneshot_mask.
1071 *
1072 * For other callers, e.g. broadcast device replacement,
1073 * tick_broadcast_oneshot_mask must not be touched as this would
1074 * set bits for CPUs which are already NOHZ, but not idle. Their
1075 * next tick_broadcast_enter() would observe the bit set and fail
1076 * to update the expiry time and the broadcast event device.
1077 */
1078 if (from_periodic) {
1079 cpumask_copy(tmpmask, tick_broadcast_mask);
1080 /* Remove the local CPU as it is obviously not idle */
1081 cpumask_clear_cpu(cpu, tmpmask);
1082 cpumask_or(tick_broadcast_oneshot_mask, tick_broadcast_oneshot_mask, tmpmask);
1083
1084 /*
1085 * Ensure that the oneshot broadcast handler will wake the
1086 * CPUs which are still waiting for periodic broadcast.
1087 */
1088 nexttick = tick_get_next_period();
1089 tick_broadcast_init_next_event(tmpmask, nexttick);
1090
1091 /*
1092 * If the underlying broadcast clock event device is
1093 * already in oneshot state, then there is nothing to do.
1094 * The device was already armed for the next tick
1095 * in tick_handle_broadcast_periodic()
1096 */
1097 if (clockevent_state_oneshot(bc))
1098 return;
1099 }
1100
1101 /*
1102 * When switching from periodic to oneshot mode arm the broadcast
1103 * device for the next tick.
1104 *
1105 * If the broadcast device has been replaced in oneshot mode and
1106 * the oneshot broadcast mask is not empty, then arm it to expire
1107 * immediately in order to reevaluate the next expiring timer.
1108 * @nexttick is 0 and therefore in the past which will cause the
1109 * clockevent code to force an event.
1110 *
1111 * For both cases the programming can be avoided when the oneshot
1112 * broadcast mask is empty.
1113 *
1114 * tick_broadcast_set_event() implicitly switches the broadcast
1115 * device to oneshot state.
1116 */
1117 if (!cpumask_empty(tick_broadcast_oneshot_mask))
1118 tick_broadcast_set_event(bc, cpu, nexttick);
1119}
1120
1121/*
1122 * Select oneshot operating mode for the broadcast device
1123 */
1124void tick_broadcast_switch_to_oneshot(void)
1125{
1126 struct clock_event_device *bc;
1127 enum tick_device_mode oldmode;
1128 unsigned long flags;
1129
1130 raw_spin_lock_irqsave(&tick_broadcast_lock, flags);
1131
1132 oldmode = tick_broadcast_device.mode;
1133 tick_broadcast_device.mode = TICKDEV_MODE_ONESHOT;
1134 bc = tick_broadcast_device.evtdev;
1135 if (bc)
1136 tick_broadcast_setup_oneshot(bc, oldmode == TICKDEV_MODE_PERIODIC);
1137
1138 raw_spin_unlock_irqrestore(&tick_broadcast_lock, flags);
1139}
1140
1141#ifdef CONFIG_HOTPLUG_CPU
1142void hotplug_cpu__broadcast_tick_pull(int deadcpu)
1143{
1144 struct clock_event_device *bc;
1145 unsigned long flags;
1146
1147 raw_spin_lock_irqsave(&tick_broadcast_lock, flags);
1148 bc = tick_broadcast_device.evtdev;
1149
1150 if (bc && broadcast_needs_cpu(bc, deadcpu)) {
1151 /* This moves the broadcast assignment to this CPU: */
1152 clockevents_program_event(bc, bc->next_event, 1);
1153 }
1154 raw_spin_unlock_irqrestore(&tick_broadcast_lock, flags);
1155}
1156
1157/*
1158 * Remove a dying CPU from broadcasting
1159 */
1160static void tick_broadcast_oneshot_offline(unsigned int cpu)
1161{
1162 if (tick_get_oneshot_wakeup_device(cpu))
1163 tick_set_oneshot_wakeup_device(NULL, cpu);
1164
1165 /*
1166 * Clear the broadcast masks for the dead cpu, but do not stop
1167 * the broadcast device!
1168 */
1169 cpumask_clear_cpu(cpu, tick_broadcast_oneshot_mask);
1170 cpumask_clear_cpu(cpu, tick_broadcast_pending_mask);
1171 cpumask_clear_cpu(cpu, tick_broadcast_force_mask);
1172}
1173#endif
1174
1175/*
1176 * Check, whether the broadcast device is in one shot mode
1177 */
1178int tick_broadcast_oneshot_active(void)
1179{
1180 return tick_broadcast_device.mode == TICKDEV_MODE_ONESHOT;
1181}
1182
1183/*
1184 * Check whether the broadcast device supports oneshot.
1185 */
1186bool tick_broadcast_oneshot_available(void)
1187{
1188 struct clock_event_device *bc = tick_broadcast_device.evtdev;
1189
1190 return bc ? bc->features & CLOCK_EVT_FEAT_ONESHOT : false;
1191}
1192
1193#else
1194int __tick_broadcast_oneshot_control(enum tick_broadcast_state state)
1195{
1196 struct clock_event_device *bc = tick_broadcast_device.evtdev;
1197
1198 if (!bc || (bc->features & CLOCK_EVT_FEAT_HRTIMER))
1199 return -EBUSY;
1200
1201 return 0;
1202}
1203#endif
1204
1205void __init tick_broadcast_init(void)
1206{
1207 zalloc_cpumask_var(&tick_broadcast_mask, GFP_NOWAIT);
1208 zalloc_cpumask_var(&tick_broadcast_on, GFP_NOWAIT);
1209 zalloc_cpumask_var(&tmpmask, GFP_NOWAIT);
1210#ifdef CONFIG_TICK_ONESHOT
1211 zalloc_cpumask_var(&tick_broadcast_oneshot_mask, GFP_NOWAIT);
1212 zalloc_cpumask_var(&tick_broadcast_pending_mask, GFP_NOWAIT);
1213 zalloc_cpumask_var(&tick_broadcast_force_mask, GFP_NOWAIT);
1214#endif
1215}