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