Merge tag 'kbuild-v5.14' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy...
[linux-2.6-microblaze.git] / kernel / time / tick-broadcast.c
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
27 static struct tick_device tick_broadcast_device;
28 static cpumask_var_t tick_broadcast_mask __cpumask_var_read_mostly;
29 static cpumask_var_t tick_broadcast_on __cpumask_var_read_mostly;
30 static cpumask_var_t tmpmask __cpumask_var_read_mostly;
31 static int tick_broadcast_forced;
32
33 static __cacheline_aligned_in_smp DEFINE_RAW_SPINLOCK(tick_broadcast_lock);
34
35 #ifdef CONFIG_TICK_ONESHOT
36 static DEFINE_PER_CPU(struct clock_event_device *, tick_oneshot_wakeup_device);
37
38 static void tick_broadcast_setup_oneshot(struct clock_event_device *bc);
39 static void tick_broadcast_clear_oneshot(int cpu);
40 static void tick_resume_broadcast_oneshot(struct clock_event_device *bc);
41 # ifdef CONFIG_HOTPLUG_CPU
42 static void tick_broadcast_oneshot_offline(unsigned int cpu);
43 # endif
44 #else
45 static inline void tick_broadcast_setup_oneshot(struct clock_event_device *bc) { BUG(); }
46 static inline void tick_broadcast_clear_oneshot(int cpu) { }
47 static inline void tick_resume_broadcast_oneshot(struct clock_event_device *bc) { }
48 # ifdef CONFIG_HOTPLUG_CPU
49 static inline void tick_broadcast_oneshot_offline(unsigned int cpu) { }
50 # endif
51 #endif
52
53 /*
54  * Debugging: see timer_list.c
55  */
56 struct tick_device *tick_get_broadcast_device(void)
57 {
58         return &tick_broadcast_device;
59 }
60
61 struct cpumask *tick_get_broadcast_mask(void)
62 {
63         return tick_broadcast_mask;
64 }
65
66 static struct clock_event_device *tick_get_oneshot_wakeup_device(int cpu);
67
68 const 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  */
76 static 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  */
85 static 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
101 static struct clock_event_device *tick_get_oneshot_wakeup_device(int cpu)
102 {
103         return per_cpu(tick_oneshot_wakeup_device, cpu);
104 }
105
106 static 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
115 static 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;
141 set_device:
142         clockevents_exchange_device(curdev, newdev);
143         per_cpu(tick_oneshot_wakeup_device, cpu) = newdev;
144         return true;
145 }
146 #else
147 static struct clock_event_device *tick_get_oneshot_wakeup_device(int cpu)
148 {
149         return NULL;
150 }
151
152 static 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  */
162 void 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  */
208 int tick_is_broadcast_device(struct clock_event_device *dev)
209 {
210         return (dev && tick_broadcast_device.evtdev == dev);
211 }
212
213 int 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
226 static 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
231 static 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  */
246 int 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
327 int 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  */
345 static 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  */
390 static 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  */
399 static 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  */
437 void 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         }
506 out:
507         raw_spin_unlock_irqrestore(&tick_broadcast_lock, flags);
508 }
509 EXPORT_SYMBOL_GPL(tick_broadcast_control);
510
511 /*
512  * Set the periodic handler depending on broadcast on/off
513  */
514 void 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
523 static 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  */
536 void 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
548 void 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  */
570 bool 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
578 void 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
606 static cpumask_var_t tick_broadcast_oneshot_mask __cpumask_var_read_mostly;
607 static cpumask_var_t tick_broadcast_pending_mask __cpumask_var_read_mostly;
608 static cpumask_var_t tick_broadcast_force_mask __cpumask_var_read_mostly;
609
610 /*
611  * Exposed for debugging: see timer_list.c
612  */
613 struct 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  */
625 int 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  */
633 static 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
646 static 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
656 static 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  */
665 void 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  */
685 static 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
765 static 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
774 static 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
791 static 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         }
924 out:
925         raw_spin_unlock(&tick_broadcast_lock);
926         return ret;
927 }
928
929 static 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
958 int __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  */
981 static 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
987 static 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
1000 static 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  */
1019 static 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  */
1066 void 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
1082 void 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  */
1100 static 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  */
1118 int 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  */
1126 bool 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
1134 int __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
1145 void __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 }