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1/*
2 * linux/kernel/time/tick-broadcast.c
3 *
4 * This file contains functions which emulate a local clock-event
5 * device via a broadcast event source.
6 *
7 * Copyright(C) 2005-2006, Thomas Gleixner <tglx@linutronix.de>
8 * Copyright(C) 2005-2007, Red Hat, Inc., Ingo Molnar
9 * Copyright(C) 2006-2007, Timesys Corp., Thomas Gleixner
10 *
11 * This code is licenced under the GPL version 2. For details see
12 * kernel-base/COPYING.
13 */
14#include <linux/cpu.h>
15#include <linux/err.h>
16#include <linux/hrtimer.h>
17#include <linux/interrupt.h>
18#include <linux/percpu.h>
19#include <linux/profile.h>
20#include <linux/sched.h>
21#include <linux/smp.h>
22#include <linux/module.h>
23
24#include "tick-internal.h"
25
26/*
27 * Broadcast support for broken x86 hardware, where the local apic
28 * timer stops in C3 state.
29 */
30
31static struct tick_device tick_broadcast_device;
32static cpumask_var_t tick_broadcast_mask;
33static cpumask_var_t tick_broadcast_on;
34static cpumask_var_t tmpmask;
35static DEFINE_RAW_SPINLOCK(tick_broadcast_lock);
36static int tick_broadcast_force;
37
38#ifdef CONFIG_TICK_ONESHOT
39static void tick_broadcast_clear_oneshot(int cpu);
40#else
41static inline void tick_broadcast_clear_oneshot(int cpu) { }
42#endif
43
44/*
45 * Debugging: see timer_list.c
46 */
47struct tick_device *tick_get_broadcast_device(void)
48{
49 return &tick_broadcast_device;
50}
51
52struct cpumask *tick_get_broadcast_mask(void)
53{
54 return tick_broadcast_mask;
55}
56
57/*
58 * Start the device in periodic mode
59 */
60static void tick_broadcast_start_periodic(struct clock_event_device *bc)
61{
62 if (bc)
63 tick_setup_periodic(bc, 1);
64}
65
66/*
67 * Check, if the device can be utilized as broadcast device:
68 */
69static bool tick_check_broadcast_device(struct clock_event_device *curdev,
70 struct clock_event_device *newdev)
71{
72 if ((newdev->features & CLOCK_EVT_FEAT_DUMMY) ||
73 (newdev->features & CLOCK_EVT_FEAT_PERCPU) ||
74 (newdev->features & CLOCK_EVT_FEAT_C3STOP))
75 return false;
76
77 if (tick_broadcast_device.mode == TICKDEV_MODE_ONESHOT &&
78 !(newdev->features & CLOCK_EVT_FEAT_ONESHOT))
79 return false;
80
81 return !curdev || newdev->rating > curdev->rating;
82}
83
84/*
85 * Conditionally install/replace broadcast device
86 */
87void tick_install_broadcast_device(struct clock_event_device *dev)
88{
89 struct clock_event_device *cur = tick_broadcast_device.evtdev;
90
91 if (!tick_check_broadcast_device(cur, dev))
92 return;
93
94 if (!try_module_get(dev->owner))
95 return;
96
97 clockevents_exchange_device(cur, dev);
98 if (cur)
99 cur->event_handler = clockevents_handle_noop;
100 tick_broadcast_device.evtdev = dev;
101 if (!cpumask_empty(tick_broadcast_mask))
102 tick_broadcast_start_periodic(dev);
103 /*
104 * Inform all cpus about this. We might be in a situation
105 * where we did not switch to oneshot mode because the per cpu
106 * devices are affected by CLOCK_EVT_FEAT_C3STOP and the lack
107 * of a oneshot capable broadcast device. Without that
108 * notification the systems stays stuck in periodic mode
109 * forever.
110 */
111 if (dev->features & CLOCK_EVT_FEAT_ONESHOT)
112 tick_clock_notify();
113}
114
115/*
116 * Check, if the device is the broadcast device
117 */
118int tick_is_broadcast_device(struct clock_event_device *dev)
119{
120 return (dev && tick_broadcast_device.evtdev == dev);
121}
122
123int tick_broadcast_update_freq(struct clock_event_device *dev, u32 freq)
124{
125 int ret = -ENODEV;
126
127 if (tick_is_broadcast_device(dev)) {
128 raw_spin_lock(&tick_broadcast_lock);
129 ret = __clockevents_update_freq(dev, freq);
130 raw_spin_unlock(&tick_broadcast_lock);
131 }
132 return ret;
133}
134
135
136static void err_broadcast(const struct cpumask *mask)
137{
138 pr_crit_once("Failed to broadcast timer tick. Some CPUs may be unresponsive.\n");
139}
140
141static void tick_device_setup_broadcast_func(struct clock_event_device *dev)
142{
143 if (!dev->broadcast)
144 dev->broadcast = tick_broadcast;
145 if (!dev->broadcast) {
146 pr_warn_once("%s depends on broadcast, but no broadcast function available\n",
147 dev->name);
148 dev->broadcast = err_broadcast;
149 }
150}
151
152/*
153 * Check, if the device is disfunctional and a place holder, which
154 * needs to be handled by the broadcast device.
155 */
156int tick_device_uses_broadcast(struct clock_event_device *dev, int cpu)
157{
158 struct clock_event_device *bc = tick_broadcast_device.evtdev;
159 unsigned long flags;
160 int ret;
161
162 raw_spin_lock_irqsave(&tick_broadcast_lock, flags);
163
164 /*
165 * Devices might be registered with both periodic and oneshot
166 * mode disabled. This signals, that the device needs to be
167 * operated from the broadcast device and is a placeholder for
168 * the cpu local device.
169 */
170 if (!tick_device_is_functional(dev)) {
171 dev->event_handler = tick_handle_periodic;
172 tick_device_setup_broadcast_func(dev);
173 cpumask_set_cpu(cpu, tick_broadcast_mask);
174 if (tick_broadcast_device.mode == TICKDEV_MODE_PERIODIC)
175 tick_broadcast_start_periodic(bc);
176 else
177 tick_broadcast_setup_oneshot(bc);
178 ret = 1;
179 } else {
180 /*
181 * Clear the broadcast bit for this cpu if the
182 * device is not power state affected.
183 */
184 if (!(dev->features & CLOCK_EVT_FEAT_C3STOP))
185 cpumask_clear_cpu(cpu, tick_broadcast_mask);
186 else
187 tick_device_setup_broadcast_func(dev);
188
189 /*
190 * Clear the broadcast bit if the CPU is not in
191 * periodic broadcast on state.
192 */
193 if (!cpumask_test_cpu(cpu, tick_broadcast_on))
194 cpumask_clear_cpu(cpu, tick_broadcast_mask);
195
196 switch (tick_broadcast_device.mode) {
197 case TICKDEV_MODE_ONESHOT:
198 /*
199 * If the system is in oneshot mode we can
200 * unconditionally clear the oneshot mask bit,
201 * because the CPU is running and therefore
202 * not in an idle state which causes the power
203 * state affected device to stop. Let the
204 * caller initialize the device.
205 */
206 tick_broadcast_clear_oneshot(cpu);
207 ret = 0;
208 break;
209
210 case TICKDEV_MODE_PERIODIC:
211 /*
212 * If the system is in periodic mode, check
213 * whether the broadcast device can be
214 * switched off now.
215 */
216 if (cpumask_empty(tick_broadcast_mask) && bc)
217 clockevents_shutdown(bc);
218 /*
219 * If we kept the cpu in the broadcast mask,
220 * tell the caller to leave the per cpu device
221 * in shutdown state. The periodic interrupt
222 * is delivered by the broadcast device.
223 */
224 ret = cpumask_test_cpu(cpu, tick_broadcast_mask);
225 break;
226 default:
227 /* Nothing to do */
228 ret = 0;
229 break;
230 }
231 }
232 raw_spin_unlock_irqrestore(&tick_broadcast_lock, flags);
233 return ret;
234}
235
236#ifdef CONFIG_GENERIC_CLOCKEVENTS_BROADCAST
237int tick_receive_broadcast(void)
238{
239 struct tick_device *td = this_cpu_ptr(&tick_cpu_device);
240 struct clock_event_device *evt = td->evtdev;
241
242 if (!evt)
243 return -ENODEV;
244
245 if (!evt->event_handler)
246 return -EINVAL;
247
248 evt->event_handler(evt);
249 return 0;
250}
251#endif
252
253/*
254 * Broadcast the event to the cpus, which are set in the mask (mangled).
255 */
256static void tick_do_broadcast(struct cpumask *mask)
257{
258 int cpu = smp_processor_id();
259 struct tick_device *td;
260
261 /*
262 * Check, if the current cpu is in the mask
263 */
264 if (cpumask_test_cpu(cpu, mask)) {
265 cpumask_clear_cpu(cpu, mask);
266 td = &per_cpu(tick_cpu_device, cpu);
267 td->evtdev->event_handler(td->evtdev);
268 }
269
270 if (!cpumask_empty(mask)) {
271 /*
272 * It might be necessary to actually check whether the devices
273 * have different broadcast functions. For now, just use the
274 * one of the first device. This works as long as we have this
275 * misfeature only on x86 (lapic)
276 */
277 td = &per_cpu(tick_cpu_device, cpumask_first(mask));
278 td->evtdev->broadcast(mask);
279 }
280}
281
282/*
283 * Periodic broadcast:
284 * - invoke the broadcast handlers
285 */
286static void tick_do_periodic_broadcast(void)
287{
288 cpumask_and(tmpmask, cpu_online_mask, tick_broadcast_mask);
289 tick_do_broadcast(tmpmask);
290}
291
292/*
293 * Event handler for periodic broadcast ticks
294 */
295static void tick_handle_periodic_broadcast(struct clock_event_device *dev)
296{
297 ktime_t next;
298
299 raw_spin_lock(&tick_broadcast_lock);
300
301 tick_do_periodic_broadcast();
302
303 /*
304 * The device is in periodic mode. No reprogramming necessary:
305 */
306 if (dev->mode == CLOCK_EVT_MODE_PERIODIC)
307 goto unlock;
308
309 /*
310 * Setup the next period for devices, which do not have
311 * periodic mode. We read dev->next_event first and add to it
312 * when the event already expired. clockevents_program_event()
313 * sets dev->next_event only when the event is really
314 * programmed to the device.
315 */
316 for (next = dev->next_event; ;) {
317 next = ktime_add(next, tick_period);
318
319 if (!clockevents_program_event(dev, next, false))
320 goto unlock;
321 tick_do_periodic_broadcast();
322 }
323unlock:
324 raw_spin_unlock(&tick_broadcast_lock);
325}
326
327/*
328 * Powerstate information: The system enters/leaves a state, where
329 * affected devices might stop
330 */
331static void tick_do_broadcast_on_off(unsigned long *reason)
332{
333 struct clock_event_device *bc, *dev;
334 struct tick_device *td;
335 unsigned long flags;
336 int cpu, bc_stopped;
337
338 raw_spin_lock_irqsave(&tick_broadcast_lock, flags);
339
340 cpu = smp_processor_id();
341 td = &per_cpu(tick_cpu_device, cpu);
342 dev = td->evtdev;
343 bc = tick_broadcast_device.evtdev;
344
345 /*
346 * Is the device not affected by the powerstate ?
347 */
348 if (!dev || !(dev->features & CLOCK_EVT_FEAT_C3STOP))
349 goto out;
350
351 if (!tick_device_is_functional(dev))
352 goto out;
353
354 bc_stopped = cpumask_empty(tick_broadcast_mask);
355
356 switch (*reason) {
357 case CLOCK_EVT_NOTIFY_BROADCAST_ON:
358 case CLOCK_EVT_NOTIFY_BROADCAST_FORCE:
359 cpumask_set_cpu(cpu, tick_broadcast_on);
360 if (!cpumask_test_and_set_cpu(cpu, tick_broadcast_mask)) {
361 if (tick_broadcast_device.mode ==
362 TICKDEV_MODE_PERIODIC)
363 clockevents_shutdown(dev);
364 }
365 if (*reason == CLOCK_EVT_NOTIFY_BROADCAST_FORCE)
366 tick_broadcast_force = 1;
367 break;
368 case CLOCK_EVT_NOTIFY_BROADCAST_OFF:
369 if (tick_broadcast_force)
370 break;
371 cpumask_clear_cpu(cpu, tick_broadcast_on);
372 if (!tick_device_is_functional(dev))
373 break;
374 if (cpumask_test_and_clear_cpu(cpu, tick_broadcast_mask)) {
375 if (tick_broadcast_device.mode ==
376 TICKDEV_MODE_PERIODIC)
377 tick_setup_periodic(dev, 0);
378 }
379 break;
380 }
381
382 if (cpumask_empty(tick_broadcast_mask)) {
383 if (!bc_stopped)
384 clockevents_shutdown(bc);
385 } else if (bc_stopped) {
386 if (tick_broadcast_device.mode == TICKDEV_MODE_PERIODIC)
387 tick_broadcast_start_periodic(bc);
388 else
389 tick_broadcast_setup_oneshot(bc);
390 }
391out:
392 raw_spin_unlock_irqrestore(&tick_broadcast_lock, flags);
393}
394
395/*
396 * Powerstate information: The system enters/leaves a state, where
397 * affected devices might stop.
398 */
399void tick_broadcast_on_off(unsigned long reason, int *oncpu)
400{
401 if (!cpumask_test_cpu(*oncpu, cpu_online_mask))
402 printk(KERN_ERR "tick-broadcast: ignoring broadcast for "
403 "offline CPU #%d\n", *oncpu);
404 else
405 tick_do_broadcast_on_off(&reason);
406}
407
408/*
409 * Set the periodic handler depending on broadcast on/off
410 */
411void tick_set_periodic_handler(struct clock_event_device *dev, int broadcast)
412{
413 if (!broadcast)
414 dev->event_handler = tick_handle_periodic;
415 else
416 dev->event_handler = tick_handle_periodic_broadcast;
417}
418
419/*
420 * Remove a CPU from broadcasting
421 */
422void tick_shutdown_broadcast(unsigned int *cpup)
423{
424 struct clock_event_device *bc;
425 unsigned long flags;
426 unsigned int cpu = *cpup;
427
428 raw_spin_lock_irqsave(&tick_broadcast_lock, flags);
429
430 bc = tick_broadcast_device.evtdev;
431 cpumask_clear_cpu(cpu, tick_broadcast_mask);
432 cpumask_clear_cpu(cpu, tick_broadcast_on);
433
434 if (tick_broadcast_device.mode == TICKDEV_MODE_PERIODIC) {
435 if (bc && cpumask_empty(tick_broadcast_mask))
436 clockevents_shutdown(bc);
437 }
438
439 raw_spin_unlock_irqrestore(&tick_broadcast_lock, flags);
440}
441
442void tick_suspend_broadcast(void)
443{
444 struct clock_event_device *bc;
445 unsigned long flags;
446
447 raw_spin_lock_irqsave(&tick_broadcast_lock, flags);
448
449 bc = tick_broadcast_device.evtdev;
450 if (bc)
451 clockevents_shutdown(bc);
452
453 raw_spin_unlock_irqrestore(&tick_broadcast_lock, flags);
454}
455
456int tick_resume_broadcast(void)
457{
458 struct clock_event_device *bc;
459 unsigned long flags;
460 int broadcast = 0;
461
462 raw_spin_lock_irqsave(&tick_broadcast_lock, flags);
463
464 bc = tick_broadcast_device.evtdev;
465
466 if (bc) {
467 clockevents_set_mode(bc, CLOCK_EVT_MODE_RESUME);
468
469 switch (tick_broadcast_device.mode) {
470 case TICKDEV_MODE_PERIODIC:
471 if (!cpumask_empty(tick_broadcast_mask))
472 tick_broadcast_start_periodic(bc);
473 broadcast = cpumask_test_cpu(smp_processor_id(),
474 tick_broadcast_mask);
475 break;
476 case TICKDEV_MODE_ONESHOT:
477 if (!cpumask_empty(tick_broadcast_mask))
478 broadcast = tick_resume_broadcast_oneshot(bc);
479 break;
480 }
481 }
482 raw_spin_unlock_irqrestore(&tick_broadcast_lock, flags);
483
484 return broadcast;
485}
486
487
488#ifdef CONFIG_TICK_ONESHOT
489
490static cpumask_var_t tick_broadcast_oneshot_mask;
491static cpumask_var_t tick_broadcast_pending_mask;
492static cpumask_var_t tick_broadcast_force_mask;
493
494/*
495 * Exposed for debugging: see timer_list.c
496 */
497struct cpumask *tick_get_broadcast_oneshot_mask(void)
498{
499 return tick_broadcast_oneshot_mask;
500}
501
502/*
503 * Called before going idle with interrupts disabled. Checks whether a
504 * broadcast event from the other core is about to happen. We detected
505 * that in tick_broadcast_oneshot_control(). The callsite can use this
506 * to avoid a deep idle transition as we are about to get the
507 * broadcast IPI right away.
508 */
509int tick_check_broadcast_expired(void)
510{
511 return cpumask_test_cpu(smp_processor_id(), tick_broadcast_force_mask);
512}
513
514/*
515 * Set broadcast interrupt affinity
516 */
517static void tick_broadcast_set_affinity(struct clock_event_device *bc,
518 const struct cpumask *cpumask)
519{
520 if (!(bc->features & CLOCK_EVT_FEAT_DYNIRQ))
521 return;
522
523 if (cpumask_equal(bc->cpumask, cpumask))
524 return;
525
526 bc->cpumask = cpumask;
527 irq_set_affinity(bc->irq, bc->cpumask);
528}
529
530static int tick_broadcast_set_event(struct clock_event_device *bc, int cpu,
531 ktime_t expires, int force)
532{
533 int ret;
534
535 if (bc->mode != CLOCK_EVT_MODE_ONESHOT)
536 clockevents_set_mode(bc, CLOCK_EVT_MODE_ONESHOT);
537
538 ret = clockevents_program_event(bc, expires, force);
539 if (!ret)
540 tick_broadcast_set_affinity(bc, cpumask_of(cpu));
541 return ret;
542}
543
544int tick_resume_broadcast_oneshot(struct clock_event_device *bc)
545{
546 clockevents_set_mode(bc, CLOCK_EVT_MODE_ONESHOT);
547 return 0;
548}
549
550/*
551 * Called from irq_enter() when idle was interrupted to reenable the
552 * per cpu device.
553 */
554void tick_check_oneshot_broadcast_this_cpu(void)
555{
556 if (cpumask_test_cpu(smp_processor_id(), tick_broadcast_oneshot_mask)) {
557 struct tick_device *td = &__get_cpu_var(tick_cpu_device);
558
559 /*
560 * We might be in the middle of switching over from
561 * periodic to oneshot. If the CPU has not yet
562 * switched over, leave the device alone.
563 */
564 if (td->mode == TICKDEV_MODE_ONESHOT) {
565 clockevents_set_mode(td->evtdev,
566 CLOCK_EVT_MODE_ONESHOT);
567 }
568 }
569}
570
571/*
572 * Handle oneshot mode broadcasting
573 */
574static void tick_handle_oneshot_broadcast(struct clock_event_device *dev)
575{
576 struct tick_device *td;
577 ktime_t now, next_event;
578 int cpu, next_cpu = 0;
579
580 raw_spin_lock(&tick_broadcast_lock);
581again:
582 dev->next_event.tv64 = KTIME_MAX;
583 next_event.tv64 = KTIME_MAX;
584 cpumask_clear(tmpmask);
585 now = ktime_get();
586 /* Find all expired events */
587 for_each_cpu(cpu, tick_broadcast_oneshot_mask) {
588 td = &per_cpu(tick_cpu_device, cpu);
589 if (td->evtdev->next_event.tv64 <= now.tv64) {
590 cpumask_set_cpu(cpu, tmpmask);
591 /*
592 * Mark the remote cpu in the pending mask, so
593 * it can avoid reprogramming the cpu local
594 * timer in tick_broadcast_oneshot_control().
595 */
596 cpumask_set_cpu(cpu, tick_broadcast_pending_mask);
597 } else if (td->evtdev->next_event.tv64 < next_event.tv64) {
598 next_event.tv64 = td->evtdev->next_event.tv64;
599 next_cpu = cpu;
600 }
601 }
602
603 /*
604 * Remove the current cpu from the pending mask. The event is
605 * delivered immediately in tick_do_broadcast() !
606 */
607 cpumask_clear_cpu(smp_processor_id(), tick_broadcast_pending_mask);
608
609 /* Take care of enforced broadcast requests */
610 cpumask_or(tmpmask, tmpmask, tick_broadcast_force_mask);
611 cpumask_clear(tick_broadcast_force_mask);
612
613 /*
614 * Sanity check. Catch the case where we try to broadcast to
615 * offline cpus.
616 */
617 if (WARN_ON_ONCE(!cpumask_subset(tmpmask, cpu_online_mask)))
618 cpumask_and(tmpmask, tmpmask, cpu_online_mask);
619
620 /*
621 * Wakeup the cpus which have an expired event.
622 */
623 tick_do_broadcast(tmpmask);
624
625 /*
626 * Two reasons for reprogram:
627 *
628 * - The global event did not expire any CPU local
629 * events. This happens in dyntick mode, as the maximum PIT
630 * delta is quite small.
631 *
632 * - There are pending events on sleeping CPUs which were not
633 * in the event mask
634 */
635 if (next_event.tv64 != KTIME_MAX) {
636 /*
637 * Rearm the broadcast device. If event expired,
638 * repeat the above
639 */
640 if (tick_broadcast_set_event(dev, next_cpu, next_event, 0))
641 goto again;
642 }
643 raw_spin_unlock(&tick_broadcast_lock);
644}
645
646static int broadcast_needs_cpu(struct clock_event_device *bc, int cpu)
647{
648 if (!(bc->features & CLOCK_EVT_FEAT_HRTIMER))
649 return 0;
650 if (bc->next_event.tv64 == KTIME_MAX)
651 return 0;
652 return bc->bound_on == cpu ? -EBUSY : 0;
653}
654
655static void broadcast_shutdown_local(struct clock_event_device *bc,
656 struct clock_event_device *dev)
657{
658 /*
659 * For hrtimer based broadcasting we cannot shutdown the cpu
660 * local device if our own event is the first one to expire or
661 * if we own the broadcast timer.
662 */
663 if (bc->features & CLOCK_EVT_FEAT_HRTIMER) {
664 if (broadcast_needs_cpu(bc, smp_processor_id()))
665 return;
666 if (dev->next_event.tv64 < bc->next_event.tv64)
667 return;
668 }
669 clockevents_set_mode(dev, CLOCK_EVT_MODE_SHUTDOWN);
670}
671
672static void broadcast_move_bc(int deadcpu)
673{
674 struct clock_event_device *bc = tick_broadcast_device.evtdev;
675
676 if (!bc || !broadcast_needs_cpu(bc, deadcpu))
677 return;
678 /* This moves the broadcast assignment to this cpu */
679 clockevents_program_event(bc, bc->next_event, 1);
680}
681
682/*
683 * Powerstate information: The system enters/leaves a state, where
684 * affected devices might stop
685 * Returns 0 on success, -EBUSY if the cpu is used to broadcast wakeups.
686 */
687int tick_broadcast_oneshot_control(unsigned long reason)
688{
689 struct clock_event_device *bc, *dev;
690 struct tick_device *td;
691 unsigned long flags;
692 ktime_t now;
693 int cpu, ret = 0;
694
695 /*
696 * Periodic mode does not care about the enter/exit of power
697 * states
698 */
699 if (tick_broadcast_device.mode == TICKDEV_MODE_PERIODIC)
700 return 0;
701
702 /*
703 * We are called with preemtion disabled from the depth of the
704 * idle code, so we can't be moved away.
705 */
706 cpu = smp_processor_id();
707 td = &per_cpu(tick_cpu_device, cpu);
708 dev = td->evtdev;
709
710 if (!(dev->features & CLOCK_EVT_FEAT_C3STOP))
711 return 0;
712
713 bc = tick_broadcast_device.evtdev;
714
715 raw_spin_lock_irqsave(&tick_broadcast_lock, flags);
716 if (reason == CLOCK_EVT_NOTIFY_BROADCAST_ENTER) {
717 if (!cpumask_test_and_set_cpu(cpu, tick_broadcast_oneshot_mask)) {
718 WARN_ON_ONCE(cpumask_test_cpu(cpu, tick_broadcast_pending_mask));
719 broadcast_shutdown_local(bc, dev);
720 /*
721 * We only reprogram the broadcast timer if we
722 * did not mark ourself in the force mask and
723 * if the cpu local event is earlier than the
724 * broadcast event. If the current CPU is in
725 * the force mask, then we are going to be
726 * woken by the IPI right away.
727 */
728 if (!cpumask_test_cpu(cpu, tick_broadcast_force_mask) &&
729 dev->next_event.tv64 < bc->next_event.tv64)
730 tick_broadcast_set_event(bc, cpu, dev->next_event, 1);
731 }
732 /*
733 * If the current CPU owns the hrtimer broadcast
734 * mechanism, it cannot go deep idle and we remove the
735 * CPU from the broadcast mask. We don't have to go
736 * through the EXIT path as the local timer is not
737 * shutdown.
738 */
739 ret = broadcast_needs_cpu(bc, cpu);
740 if (ret)
741 cpumask_clear_cpu(cpu, tick_broadcast_oneshot_mask);
742 } else {
743 if (cpumask_test_and_clear_cpu(cpu, tick_broadcast_oneshot_mask)) {
744 clockevents_set_mode(dev, CLOCK_EVT_MODE_ONESHOT);
745 /*
746 * The cpu which was handling the broadcast
747 * timer marked this cpu in the broadcast
748 * pending mask and fired the broadcast
749 * IPI. So we are going to handle the expired
750 * event anyway via the broadcast IPI
751 * handler. No need to reprogram the timer
752 * with an already expired event.
753 */
754 if (cpumask_test_and_clear_cpu(cpu,
755 tick_broadcast_pending_mask))
756 goto out;
757
758 /*
759 * Bail out if there is no next event.
760 */
761 if (dev->next_event.tv64 == KTIME_MAX)
762 goto out;
763 /*
764 * If the pending bit is not set, then we are
765 * either the CPU handling the broadcast
766 * interrupt or we got woken by something else.
767 *
768 * We are not longer in the broadcast mask, so
769 * if the cpu local expiry time is already
770 * reached, we would reprogram the cpu local
771 * timer with an already expired event.
772 *
773 * This can lead to a ping-pong when we return
774 * to idle and therefor rearm the broadcast
775 * timer before the cpu local timer was able
776 * to fire. This happens because the forced
777 * reprogramming makes sure that the event
778 * will happen in the future and depending on
779 * the min_delta setting this might be far
780 * enough out that the ping-pong starts.
781 *
782 * If the cpu local next_event has expired
783 * then we know that the broadcast timer
784 * next_event has expired as well and
785 * broadcast is about to be handled. So we
786 * avoid reprogramming and enforce that the
787 * broadcast handler, which did not run yet,
788 * will invoke the cpu local handler.
789 *
790 * We cannot call the handler directly from
791 * here, because we might be in a NOHZ phase
792 * and we did not go through the irq_enter()
793 * nohz fixups.
794 */
795 now = ktime_get();
796 if (dev->next_event.tv64 <= now.tv64) {
797 cpumask_set_cpu(cpu, tick_broadcast_force_mask);
798 goto out;
799 }
800 /*
801 * We got woken by something else. Reprogram
802 * the cpu local timer device.
803 */
804 tick_program_event(dev->next_event, 1);
805 }
806 }
807out:
808 raw_spin_unlock_irqrestore(&tick_broadcast_lock, flags);
809 return ret;
810}
811
812/*
813 * Reset the one shot broadcast for a cpu
814 *
815 * Called with tick_broadcast_lock held
816 */
817static void tick_broadcast_clear_oneshot(int cpu)
818{
819 cpumask_clear_cpu(cpu, tick_broadcast_oneshot_mask);
820 cpumask_clear_cpu(cpu, tick_broadcast_pending_mask);
821}
822
823static void tick_broadcast_init_next_event(struct cpumask *mask,
824 ktime_t expires)
825{
826 struct tick_device *td;
827 int cpu;
828
829 for_each_cpu(cpu, mask) {
830 td = &per_cpu(tick_cpu_device, cpu);
831 if (td->evtdev)
832 td->evtdev->next_event = expires;
833 }
834}
835
836/**
837 * tick_broadcast_setup_oneshot - setup the broadcast device
838 */
839void tick_broadcast_setup_oneshot(struct clock_event_device *bc)
840{
841 int cpu = smp_processor_id();
842
843 /* Set it up only once ! */
844 if (bc->event_handler != tick_handle_oneshot_broadcast) {
845 int was_periodic = bc->mode == CLOCK_EVT_MODE_PERIODIC;
846
847 bc->event_handler = tick_handle_oneshot_broadcast;
848
849 /*
850 * We must be careful here. There might be other CPUs
851 * waiting for periodic broadcast. We need to set the
852 * oneshot_mask bits for those and program the
853 * broadcast device to fire.
854 */
855 cpumask_copy(tmpmask, tick_broadcast_mask);
856 cpumask_clear_cpu(cpu, tmpmask);
857 cpumask_or(tick_broadcast_oneshot_mask,
858 tick_broadcast_oneshot_mask, tmpmask);
859
860 if (was_periodic && !cpumask_empty(tmpmask)) {
861 clockevents_set_mode(bc, CLOCK_EVT_MODE_ONESHOT);
862 tick_broadcast_init_next_event(tmpmask,
863 tick_next_period);
864 tick_broadcast_set_event(bc, cpu, tick_next_period, 1);
865 } else
866 bc->next_event.tv64 = KTIME_MAX;
867 } else {
868 /*
869 * The first cpu which switches to oneshot mode sets
870 * the bit for all other cpus which are in the general
871 * (periodic) broadcast mask. So the bit is set and
872 * would prevent the first broadcast enter after this
873 * to program the bc device.
874 */
875 tick_broadcast_clear_oneshot(cpu);
876 }
877}
878
879/*
880 * Select oneshot operating mode for the broadcast device
881 */
882void tick_broadcast_switch_to_oneshot(void)
883{
884 struct clock_event_device *bc;
885 unsigned long flags;
886
887 raw_spin_lock_irqsave(&tick_broadcast_lock, flags);
888
889 tick_broadcast_device.mode = TICKDEV_MODE_ONESHOT;
890 bc = tick_broadcast_device.evtdev;
891 if (bc)
892 tick_broadcast_setup_oneshot(bc);
893
894 raw_spin_unlock_irqrestore(&tick_broadcast_lock, flags);
895}
896
897
898/*
899 * Remove a dead CPU from broadcasting
900 */
901void tick_shutdown_broadcast_oneshot(unsigned int *cpup)
902{
903 unsigned long flags;
904 unsigned int cpu = *cpup;
905
906 raw_spin_lock_irqsave(&tick_broadcast_lock, flags);
907
908 /*
909 * Clear the broadcast masks for the dead cpu, but do not stop
910 * the broadcast device!
911 */
912 cpumask_clear_cpu(cpu, tick_broadcast_oneshot_mask);
913 cpumask_clear_cpu(cpu, tick_broadcast_pending_mask);
914 cpumask_clear_cpu(cpu, tick_broadcast_force_mask);
915
916 broadcast_move_bc(cpu);
917
918 raw_spin_unlock_irqrestore(&tick_broadcast_lock, flags);
919}
920
921/*
922 * Check, whether the broadcast device is in one shot mode
923 */
924int tick_broadcast_oneshot_active(void)
925{
926 return tick_broadcast_device.mode == TICKDEV_MODE_ONESHOT;
927}
928
929/*
930 * Check whether the broadcast device supports oneshot.
931 */
932bool tick_broadcast_oneshot_available(void)
933{
934 struct clock_event_device *bc = tick_broadcast_device.evtdev;
935
936 return bc ? bc->features & CLOCK_EVT_FEAT_ONESHOT : false;
937}
938
939#endif
940
941void __init tick_broadcast_init(void)
942{
943 zalloc_cpumask_var(&tick_broadcast_mask, GFP_NOWAIT);
944 zalloc_cpumask_var(&tick_broadcast_on, GFP_NOWAIT);
945 zalloc_cpumask_var(&tmpmask, GFP_NOWAIT);
946#ifdef CONFIG_TICK_ONESHOT
947 zalloc_cpumask_var(&tick_broadcast_oneshot_mask, GFP_NOWAIT);
948 zalloc_cpumask_var(&tick_broadcast_pending_mask, GFP_NOWAIT);
949 zalloc_cpumask_var(&tick_broadcast_force_mask, GFP_NOWAIT);
950#endif
951}
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
22#include "tick-internal.h"
23
24/*
25 * Broadcast support for broken x86 hardware, where the local apic
26 * timer stops in C3 state.
27 */
28
29static struct tick_device tick_broadcast_device;
30/* FIXME: Use cpumask_var_t. */
31static DECLARE_BITMAP(tick_broadcast_mask, NR_CPUS);
32static DECLARE_BITMAP(tmpmask, NR_CPUS);
33static DEFINE_RAW_SPINLOCK(tick_broadcast_lock);
34static int tick_broadcast_force;
35
36#ifdef CONFIG_TICK_ONESHOT
37static void tick_broadcast_clear_oneshot(int cpu);
38#else
39static inline void tick_broadcast_clear_oneshot(int cpu) { }
40#endif
41
42/*
43 * Debugging: see timer_list.c
44 */
45struct tick_device *tick_get_broadcast_device(void)
46{
47 return &tick_broadcast_device;
48}
49
50struct cpumask *tick_get_broadcast_mask(void)
51{
52 return to_cpumask(tick_broadcast_mask);
53}
54
55/*
56 * Start the device in periodic mode
57 */
58static void tick_broadcast_start_periodic(struct clock_event_device *bc)
59{
60 if (bc)
61 tick_setup_periodic(bc, 1);
62}
63
64/*
65 * Check, if the device can be utilized as broadcast device:
66 */
67int tick_check_broadcast_device(struct clock_event_device *dev)
68{
69 if ((tick_broadcast_device.evtdev &&
70 tick_broadcast_device.evtdev->rating >= dev->rating) ||
71 (dev->features & CLOCK_EVT_FEAT_C3STOP))
72 return 0;
73
74 clockevents_exchange_device(NULL, dev);
75 tick_broadcast_device.evtdev = dev;
76 if (!cpumask_empty(tick_get_broadcast_mask()))
77 tick_broadcast_start_periodic(dev);
78 return 1;
79}
80
81/*
82 * Check, if the device is the broadcast device
83 */
84int tick_is_broadcast_device(struct clock_event_device *dev)
85{
86 return (dev && tick_broadcast_device.evtdev == dev);
87}
88
89/*
90 * Check, if the device is disfunctional and a place holder, which
91 * needs to be handled by the broadcast device.
92 */
93int tick_device_uses_broadcast(struct clock_event_device *dev, int cpu)
94{
95 unsigned long flags;
96 int ret = 0;
97
98 raw_spin_lock_irqsave(&tick_broadcast_lock, flags);
99
100 /*
101 * Devices might be registered with both periodic and oneshot
102 * mode disabled. This signals, that the device needs to be
103 * operated from the broadcast device and is a placeholder for
104 * the cpu local device.
105 */
106 if (!tick_device_is_functional(dev)) {
107 dev->event_handler = tick_handle_periodic;
108 cpumask_set_cpu(cpu, tick_get_broadcast_mask());
109 tick_broadcast_start_periodic(tick_broadcast_device.evtdev);
110 ret = 1;
111 } else {
112 /*
113 * When the new device is not affected by the stop
114 * feature and the cpu is marked in the broadcast mask
115 * then clear the broadcast bit.
116 */
117 if (!(dev->features & CLOCK_EVT_FEAT_C3STOP)) {
118 int cpu = smp_processor_id();
119
120 cpumask_clear_cpu(cpu, tick_get_broadcast_mask());
121 tick_broadcast_clear_oneshot(cpu);
122 }
123 }
124 raw_spin_unlock_irqrestore(&tick_broadcast_lock, flags);
125 return ret;
126}
127
128/*
129 * Broadcast the event to the cpus, which are set in the mask (mangled).
130 */
131static void tick_do_broadcast(struct cpumask *mask)
132{
133 int cpu = smp_processor_id();
134 struct tick_device *td;
135
136 /*
137 * Check, if the current cpu is in the mask
138 */
139 if (cpumask_test_cpu(cpu, mask)) {
140 cpumask_clear_cpu(cpu, mask);
141 td = &per_cpu(tick_cpu_device, cpu);
142 td->evtdev->event_handler(td->evtdev);
143 }
144
145 if (!cpumask_empty(mask)) {
146 /*
147 * It might be necessary to actually check whether the devices
148 * have different broadcast functions. For now, just use the
149 * one of the first device. This works as long as we have this
150 * misfeature only on x86 (lapic)
151 */
152 td = &per_cpu(tick_cpu_device, cpumask_first(mask));
153 td->evtdev->broadcast(mask);
154 }
155}
156
157/*
158 * Periodic broadcast:
159 * - invoke the broadcast handlers
160 */
161static void tick_do_periodic_broadcast(void)
162{
163 raw_spin_lock(&tick_broadcast_lock);
164
165 cpumask_and(to_cpumask(tmpmask),
166 cpu_online_mask, tick_get_broadcast_mask());
167 tick_do_broadcast(to_cpumask(tmpmask));
168
169 raw_spin_unlock(&tick_broadcast_lock);
170}
171
172/*
173 * Event handler for periodic broadcast ticks
174 */
175static void tick_handle_periodic_broadcast(struct clock_event_device *dev)
176{
177 ktime_t next;
178
179 tick_do_periodic_broadcast();
180
181 /*
182 * The device is in periodic mode. No reprogramming necessary:
183 */
184 if (dev->mode == CLOCK_EVT_MODE_PERIODIC)
185 return;
186
187 /*
188 * Setup the next period for devices, which do not have
189 * periodic mode. We read dev->next_event first and add to it
190 * when the event already expired. clockevents_program_event()
191 * sets dev->next_event only when the event is really
192 * programmed to the device.
193 */
194 for (next = dev->next_event; ;) {
195 next = ktime_add(next, tick_period);
196
197 if (!clockevents_program_event(dev, next, ktime_get()))
198 return;
199 tick_do_periodic_broadcast();
200 }
201}
202
203/*
204 * Powerstate information: The system enters/leaves a state, where
205 * affected devices might stop
206 */
207static void tick_do_broadcast_on_off(unsigned long *reason)
208{
209 struct clock_event_device *bc, *dev;
210 struct tick_device *td;
211 unsigned long flags;
212 int cpu, bc_stopped;
213
214 raw_spin_lock_irqsave(&tick_broadcast_lock, flags);
215
216 cpu = smp_processor_id();
217 td = &per_cpu(tick_cpu_device, cpu);
218 dev = td->evtdev;
219 bc = tick_broadcast_device.evtdev;
220
221 /*
222 * Is the device not affected by the powerstate ?
223 */
224 if (!dev || !(dev->features & CLOCK_EVT_FEAT_C3STOP))
225 goto out;
226
227 if (!tick_device_is_functional(dev))
228 goto out;
229
230 bc_stopped = cpumask_empty(tick_get_broadcast_mask());
231
232 switch (*reason) {
233 case CLOCK_EVT_NOTIFY_BROADCAST_ON:
234 case CLOCK_EVT_NOTIFY_BROADCAST_FORCE:
235 if (!cpumask_test_cpu(cpu, tick_get_broadcast_mask())) {
236 cpumask_set_cpu(cpu, tick_get_broadcast_mask());
237 if (tick_broadcast_device.mode ==
238 TICKDEV_MODE_PERIODIC)
239 clockevents_shutdown(dev);
240 }
241 if (*reason == CLOCK_EVT_NOTIFY_BROADCAST_FORCE)
242 tick_broadcast_force = 1;
243 break;
244 case CLOCK_EVT_NOTIFY_BROADCAST_OFF:
245 if (!tick_broadcast_force &&
246 cpumask_test_cpu(cpu, tick_get_broadcast_mask())) {
247 cpumask_clear_cpu(cpu, tick_get_broadcast_mask());
248 if (tick_broadcast_device.mode ==
249 TICKDEV_MODE_PERIODIC)
250 tick_setup_periodic(dev, 0);
251 }
252 break;
253 }
254
255 if (cpumask_empty(tick_get_broadcast_mask())) {
256 if (!bc_stopped)
257 clockevents_shutdown(bc);
258 } else if (bc_stopped) {
259 if (tick_broadcast_device.mode == TICKDEV_MODE_PERIODIC)
260 tick_broadcast_start_periodic(bc);
261 else
262 tick_broadcast_setup_oneshot(bc);
263 }
264out:
265 raw_spin_unlock_irqrestore(&tick_broadcast_lock, flags);
266}
267
268/*
269 * Powerstate information: The system enters/leaves a state, where
270 * affected devices might stop.
271 */
272void tick_broadcast_on_off(unsigned long reason, int *oncpu)
273{
274 if (!cpumask_test_cpu(*oncpu, cpu_online_mask))
275 printk(KERN_ERR "tick-broadcast: ignoring broadcast for "
276 "offline CPU #%d\n", *oncpu);
277 else
278 tick_do_broadcast_on_off(&reason);
279}
280
281/*
282 * Set the periodic handler depending on broadcast on/off
283 */
284void tick_set_periodic_handler(struct clock_event_device *dev, int broadcast)
285{
286 if (!broadcast)
287 dev->event_handler = tick_handle_periodic;
288 else
289 dev->event_handler = tick_handle_periodic_broadcast;
290}
291
292/*
293 * Remove a CPU from broadcasting
294 */
295void tick_shutdown_broadcast(unsigned int *cpup)
296{
297 struct clock_event_device *bc;
298 unsigned long flags;
299 unsigned int cpu = *cpup;
300
301 raw_spin_lock_irqsave(&tick_broadcast_lock, flags);
302
303 bc = tick_broadcast_device.evtdev;
304 cpumask_clear_cpu(cpu, tick_get_broadcast_mask());
305
306 if (tick_broadcast_device.mode == TICKDEV_MODE_PERIODIC) {
307 if (bc && cpumask_empty(tick_get_broadcast_mask()))
308 clockevents_shutdown(bc);
309 }
310
311 raw_spin_unlock_irqrestore(&tick_broadcast_lock, flags);
312}
313
314void tick_suspend_broadcast(void)
315{
316 struct clock_event_device *bc;
317 unsigned long flags;
318
319 raw_spin_lock_irqsave(&tick_broadcast_lock, flags);
320
321 bc = tick_broadcast_device.evtdev;
322 if (bc)
323 clockevents_shutdown(bc);
324
325 raw_spin_unlock_irqrestore(&tick_broadcast_lock, flags);
326}
327
328int tick_resume_broadcast(void)
329{
330 struct clock_event_device *bc;
331 unsigned long flags;
332 int broadcast = 0;
333
334 raw_spin_lock_irqsave(&tick_broadcast_lock, flags);
335
336 bc = tick_broadcast_device.evtdev;
337
338 if (bc) {
339 clockevents_set_mode(bc, CLOCK_EVT_MODE_RESUME);
340
341 switch (tick_broadcast_device.mode) {
342 case TICKDEV_MODE_PERIODIC:
343 if (!cpumask_empty(tick_get_broadcast_mask()))
344 tick_broadcast_start_periodic(bc);
345 broadcast = cpumask_test_cpu(smp_processor_id(),
346 tick_get_broadcast_mask());
347 break;
348 case TICKDEV_MODE_ONESHOT:
349 broadcast = tick_resume_broadcast_oneshot(bc);
350 break;
351 }
352 }
353 raw_spin_unlock_irqrestore(&tick_broadcast_lock, flags);
354
355 return broadcast;
356}
357
358
359#ifdef CONFIG_TICK_ONESHOT
360
361/* FIXME: use cpumask_var_t. */
362static DECLARE_BITMAP(tick_broadcast_oneshot_mask, NR_CPUS);
363
364/*
365 * Exposed for debugging: see timer_list.c
366 */
367struct cpumask *tick_get_broadcast_oneshot_mask(void)
368{
369 return to_cpumask(tick_broadcast_oneshot_mask);
370}
371
372static int tick_broadcast_set_event(ktime_t expires, int force)
373{
374 struct clock_event_device *bc = tick_broadcast_device.evtdev;
375
376 return tick_dev_program_event(bc, expires, force);
377}
378
379int tick_resume_broadcast_oneshot(struct clock_event_device *bc)
380{
381 clockevents_set_mode(bc, CLOCK_EVT_MODE_ONESHOT);
382 return 0;
383}
384
385/*
386 * Called from irq_enter() when idle was interrupted to reenable the
387 * per cpu device.
388 */
389void tick_check_oneshot_broadcast(int cpu)
390{
391 if (cpumask_test_cpu(cpu, to_cpumask(tick_broadcast_oneshot_mask))) {
392 struct tick_device *td = &per_cpu(tick_cpu_device, cpu);
393
394 clockevents_set_mode(td->evtdev, CLOCK_EVT_MODE_ONESHOT);
395 }
396}
397
398/*
399 * Handle oneshot mode broadcasting
400 */
401static void tick_handle_oneshot_broadcast(struct clock_event_device *dev)
402{
403 struct tick_device *td;
404 ktime_t now, next_event;
405 int cpu;
406
407 raw_spin_lock(&tick_broadcast_lock);
408again:
409 dev->next_event.tv64 = KTIME_MAX;
410 next_event.tv64 = KTIME_MAX;
411 cpumask_clear(to_cpumask(tmpmask));
412 now = ktime_get();
413 /* Find all expired events */
414 for_each_cpu(cpu, tick_get_broadcast_oneshot_mask()) {
415 td = &per_cpu(tick_cpu_device, cpu);
416 if (td->evtdev->next_event.tv64 <= now.tv64)
417 cpumask_set_cpu(cpu, to_cpumask(tmpmask));
418 else if (td->evtdev->next_event.tv64 < next_event.tv64)
419 next_event.tv64 = td->evtdev->next_event.tv64;
420 }
421
422 /*
423 * Wakeup the cpus which have an expired event.
424 */
425 tick_do_broadcast(to_cpumask(tmpmask));
426
427 /*
428 * Two reasons for reprogram:
429 *
430 * - The global event did not expire any CPU local
431 * events. This happens in dyntick mode, as the maximum PIT
432 * delta is quite small.
433 *
434 * - There are pending events on sleeping CPUs which were not
435 * in the event mask
436 */
437 if (next_event.tv64 != KTIME_MAX) {
438 /*
439 * Rearm the broadcast device. If event expired,
440 * repeat the above
441 */
442 if (tick_broadcast_set_event(next_event, 0))
443 goto again;
444 }
445 raw_spin_unlock(&tick_broadcast_lock);
446}
447
448/*
449 * Powerstate information: The system enters/leaves a state, where
450 * affected devices might stop
451 */
452void tick_broadcast_oneshot_control(unsigned long reason)
453{
454 struct clock_event_device *bc, *dev;
455 struct tick_device *td;
456 unsigned long flags;
457 int cpu;
458
459 /*
460 * Periodic mode does not care about the enter/exit of power
461 * states
462 */
463 if (tick_broadcast_device.mode == TICKDEV_MODE_PERIODIC)
464 return;
465
466 /*
467 * We are called with preemtion disabled from the depth of the
468 * idle code, so we can't be moved away.
469 */
470 cpu = smp_processor_id();
471 td = &per_cpu(tick_cpu_device, cpu);
472 dev = td->evtdev;
473
474 if (!(dev->features & CLOCK_EVT_FEAT_C3STOP))
475 return;
476
477 bc = tick_broadcast_device.evtdev;
478
479 raw_spin_lock_irqsave(&tick_broadcast_lock, flags);
480 if (reason == CLOCK_EVT_NOTIFY_BROADCAST_ENTER) {
481 if (!cpumask_test_cpu(cpu, tick_get_broadcast_oneshot_mask())) {
482 cpumask_set_cpu(cpu, tick_get_broadcast_oneshot_mask());
483 clockevents_set_mode(dev, CLOCK_EVT_MODE_SHUTDOWN);
484 if (dev->next_event.tv64 < bc->next_event.tv64)
485 tick_broadcast_set_event(dev->next_event, 1);
486 }
487 } else {
488 if (cpumask_test_cpu(cpu, tick_get_broadcast_oneshot_mask())) {
489 cpumask_clear_cpu(cpu,
490 tick_get_broadcast_oneshot_mask());
491 clockevents_set_mode(dev, CLOCK_EVT_MODE_ONESHOT);
492 if (dev->next_event.tv64 != KTIME_MAX)
493 tick_program_event(dev->next_event, 1);
494 }
495 }
496 raw_spin_unlock_irqrestore(&tick_broadcast_lock, flags);
497}
498
499/*
500 * Reset the one shot broadcast for a cpu
501 *
502 * Called with tick_broadcast_lock held
503 */
504static void tick_broadcast_clear_oneshot(int cpu)
505{
506 cpumask_clear_cpu(cpu, tick_get_broadcast_oneshot_mask());
507}
508
509static void tick_broadcast_init_next_event(struct cpumask *mask,
510 ktime_t expires)
511{
512 struct tick_device *td;
513 int cpu;
514
515 for_each_cpu(cpu, mask) {
516 td = &per_cpu(tick_cpu_device, cpu);
517 if (td->evtdev)
518 td->evtdev->next_event = expires;
519 }
520}
521
522/**
523 * tick_broadcast_setup_oneshot - setup the broadcast device
524 */
525void tick_broadcast_setup_oneshot(struct clock_event_device *bc)
526{
527 int cpu = smp_processor_id();
528
529 /* Set it up only once ! */
530 if (bc->event_handler != tick_handle_oneshot_broadcast) {
531 int was_periodic = bc->mode == CLOCK_EVT_MODE_PERIODIC;
532
533 bc->event_handler = tick_handle_oneshot_broadcast;
534 clockevents_set_mode(bc, CLOCK_EVT_MODE_ONESHOT);
535
536 /* Take the do_timer update */
537 tick_do_timer_cpu = cpu;
538
539 /*
540 * We must be careful here. There might be other CPUs
541 * waiting for periodic broadcast. We need to set the
542 * oneshot_mask bits for those and program the
543 * broadcast device to fire.
544 */
545 cpumask_copy(to_cpumask(tmpmask), tick_get_broadcast_mask());
546 cpumask_clear_cpu(cpu, to_cpumask(tmpmask));
547 cpumask_or(tick_get_broadcast_oneshot_mask(),
548 tick_get_broadcast_oneshot_mask(),
549 to_cpumask(tmpmask));
550
551 if (was_periodic && !cpumask_empty(to_cpumask(tmpmask))) {
552 tick_broadcast_init_next_event(to_cpumask(tmpmask),
553 tick_next_period);
554 tick_broadcast_set_event(tick_next_period, 1);
555 } else
556 bc->next_event.tv64 = KTIME_MAX;
557 } else {
558 /*
559 * The first cpu which switches to oneshot mode sets
560 * the bit for all other cpus which are in the general
561 * (periodic) broadcast mask. So the bit is set and
562 * would prevent the first broadcast enter after this
563 * to program the bc device.
564 */
565 tick_broadcast_clear_oneshot(cpu);
566 }
567}
568
569/*
570 * Select oneshot operating mode for the broadcast device
571 */
572void tick_broadcast_switch_to_oneshot(void)
573{
574 struct clock_event_device *bc;
575 unsigned long flags;
576
577 raw_spin_lock_irqsave(&tick_broadcast_lock, flags);
578
579 tick_broadcast_device.mode = TICKDEV_MODE_ONESHOT;
580 bc = tick_broadcast_device.evtdev;
581 if (bc)
582 tick_broadcast_setup_oneshot(bc);
583 raw_spin_unlock_irqrestore(&tick_broadcast_lock, flags);
584}
585
586
587/*
588 * Remove a dead CPU from broadcasting
589 */
590void tick_shutdown_broadcast_oneshot(unsigned int *cpup)
591{
592 unsigned long flags;
593 unsigned int cpu = *cpup;
594
595 raw_spin_lock_irqsave(&tick_broadcast_lock, flags);
596
597 /*
598 * Clear the broadcast mask flag for the dead cpu, but do not
599 * stop the broadcast device!
600 */
601 cpumask_clear_cpu(cpu, tick_get_broadcast_oneshot_mask());
602
603 raw_spin_unlock_irqrestore(&tick_broadcast_lock, flags);
604}
605
606/*
607 * Check, whether the broadcast device is in one shot mode
608 */
609int tick_broadcast_oneshot_active(void)
610{
611 return tick_broadcast_device.mode == TICKDEV_MODE_ONESHOT;
612}
613
614/*
615 * Check whether the broadcast device supports oneshot.
616 */
617bool tick_broadcast_oneshot_available(void)
618{
619 struct clock_event_device *bc = tick_broadcast_device.evtdev;
620
621 return bc ? bc->features & CLOCK_EVT_FEAT_ONESHOT : false;
622}
623
624#endif