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