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1/*
2 * linux/kernel/time/tick-common.c
3 *
4 * This file contains the base functions to manage periodic tick
5 * related events.
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/module.h>
22#include <trace/events/power.h>
23
24#include <asm/irq_regs.h>
25
26#include "tick-internal.h"
27
28/*
29 * Tick devices
30 */
31DEFINE_PER_CPU(struct tick_device, tick_cpu_device);
32/*
33 * Tick next event: keeps track of the tick time
34 */
35ktime_t tick_next_period;
36ktime_t tick_period;
37
38/*
39 * tick_do_timer_cpu is a timer core internal variable which holds the CPU NR
40 * which is responsible for calling do_timer(), i.e. the timekeeping stuff. This
41 * variable has two functions:
42 *
43 * 1) Prevent a thundering herd issue of a gazillion of CPUs trying to grab the
44 * timekeeping lock all at once. Only the CPU which is assigned to do the
45 * update is handling it.
46 *
47 * 2) Hand off the duty in the NOHZ idle case by setting the value to
48 * TICK_DO_TIMER_NONE, i.e. a non existing CPU. So the next cpu which looks
49 * at it will take over and keep the time keeping alive. The handover
50 * procedure also covers cpu hotplug.
51 */
52int tick_do_timer_cpu __read_mostly = TICK_DO_TIMER_BOOT;
53
54/*
55 * Debugging: see timer_list.c
56 */
57struct tick_device *tick_get_device(int cpu)
58{
59 return &per_cpu(tick_cpu_device, cpu);
60}
61
62/**
63 * tick_is_oneshot_available - check for a oneshot capable event device
64 */
65int tick_is_oneshot_available(void)
66{
67 struct clock_event_device *dev = __this_cpu_read(tick_cpu_device.evtdev);
68
69 if (!dev || !(dev->features & CLOCK_EVT_FEAT_ONESHOT))
70 return 0;
71 if (!(dev->features & CLOCK_EVT_FEAT_C3STOP))
72 return 1;
73 return tick_broadcast_oneshot_available();
74}
75
76/*
77 * Periodic tick
78 */
79static void tick_periodic(int cpu)
80{
81 if (tick_do_timer_cpu == cpu) {
82 write_seqlock(&jiffies_lock);
83
84 /* Keep track of the next tick event */
85 tick_next_period = ktime_add(tick_next_period, tick_period);
86
87 do_timer(1);
88 write_sequnlock(&jiffies_lock);
89 update_wall_time();
90 }
91
92 update_process_times(user_mode(get_irq_regs()));
93 profile_tick(CPU_PROFILING);
94}
95
96/*
97 * Event handler for periodic ticks
98 */
99void tick_handle_periodic(struct clock_event_device *dev)
100{
101 int cpu = smp_processor_id();
102 ktime_t next = dev->next_event;
103
104 tick_periodic(cpu);
105
106#if defined(CONFIG_HIGH_RES_TIMERS) || defined(CONFIG_NO_HZ_COMMON)
107 /*
108 * The cpu might have transitioned to HIGHRES or NOHZ mode via
109 * update_process_times() -> run_local_timers() ->
110 * hrtimer_run_queues().
111 */
112 if (dev->event_handler != tick_handle_periodic)
113 return;
114#endif
115
116 if (!clockevent_state_oneshot(dev))
117 return;
118 for (;;) {
119 /*
120 * Setup the next period for devices, which do not have
121 * periodic mode:
122 */
123 next = ktime_add(next, tick_period);
124
125 if (!clockevents_program_event(dev, next, false))
126 return;
127 /*
128 * Have to be careful here. If we're in oneshot mode,
129 * before we call tick_periodic() in a loop, we need
130 * to be sure we're using a real hardware clocksource.
131 * Otherwise we could get trapped in an infinite
132 * loop, as the tick_periodic() increments jiffies,
133 * which then will increment time, possibly causing
134 * the loop to trigger again and again.
135 */
136 if (timekeeping_valid_for_hres())
137 tick_periodic(cpu);
138 }
139}
140
141/*
142 * Setup the device for a periodic tick
143 */
144void tick_setup_periodic(struct clock_event_device *dev, int broadcast)
145{
146 tick_set_periodic_handler(dev, broadcast);
147
148 /* Broadcast setup ? */
149 if (!tick_device_is_functional(dev))
150 return;
151
152 if ((dev->features & CLOCK_EVT_FEAT_PERIODIC) &&
153 !tick_broadcast_oneshot_active()) {
154 clockevents_switch_state(dev, CLOCK_EVT_STATE_PERIODIC);
155 } else {
156 unsigned long seq;
157 ktime_t next;
158
159 do {
160 seq = read_seqbegin(&jiffies_lock);
161 next = tick_next_period;
162 } while (read_seqretry(&jiffies_lock, seq));
163
164 clockevents_switch_state(dev, CLOCK_EVT_STATE_ONESHOT);
165
166 for (;;) {
167 if (!clockevents_program_event(dev, next, false))
168 return;
169 next = ktime_add(next, tick_period);
170 }
171 }
172}
173
174/*
175 * Setup the tick device
176 */
177static void tick_setup_device(struct tick_device *td,
178 struct clock_event_device *newdev, int cpu,
179 const struct cpumask *cpumask)
180{
181 void (*handler)(struct clock_event_device *) = NULL;
182 ktime_t next_event = 0;
183
184 /*
185 * First device setup ?
186 */
187 if (!td->evtdev) {
188 /*
189 * If no cpu took the do_timer update, assign it to
190 * this cpu:
191 */
192 if (tick_do_timer_cpu == TICK_DO_TIMER_BOOT) {
193 if (!tick_nohz_full_cpu(cpu))
194 tick_do_timer_cpu = cpu;
195 else
196 tick_do_timer_cpu = TICK_DO_TIMER_NONE;
197 tick_next_period = ktime_get();
198 tick_period = NSEC_PER_SEC / HZ;
199 }
200
201 /*
202 * Startup in periodic mode first.
203 */
204 td->mode = TICKDEV_MODE_PERIODIC;
205 } else {
206 handler = td->evtdev->event_handler;
207 next_event = td->evtdev->next_event;
208 td->evtdev->event_handler = clockevents_handle_noop;
209 }
210
211 td->evtdev = newdev;
212
213 /*
214 * When the device is not per cpu, pin the interrupt to the
215 * current cpu:
216 */
217 if (!cpumask_equal(newdev->cpumask, cpumask))
218 irq_set_affinity(newdev->irq, cpumask);
219
220 /*
221 * When global broadcasting is active, check if the current
222 * device is registered as a placeholder for broadcast mode.
223 * This allows us to handle this x86 misfeature in a generic
224 * way. This function also returns !=0 when we keep the
225 * current active broadcast state for this CPU.
226 */
227 if (tick_device_uses_broadcast(newdev, cpu))
228 return;
229
230 if (td->mode == TICKDEV_MODE_PERIODIC)
231 tick_setup_periodic(newdev, 0);
232 else
233 tick_setup_oneshot(newdev, handler, next_event);
234}
235
236void tick_install_replacement(struct clock_event_device *newdev)
237{
238 struct tick_device *td = this_cpu_ptr(&tick_cpu_device);
239 int cpu = smp_processor_id();
240
241 clockevents_exchange_device(td->evtdev, newdev);
242 tick_setup_device(td, newdev, cpu, cpumask_of(cpu));
243 if (newdev->features & CLOCK_EVT_FEAT_ONESHOT)
244 tick_oneshot_notify();
245}
246
247static bool tick_check_percpu(struct clock_event_device *curdev,
248 struct clock_event_device *newdev, int cpu)
249{
250 if (!cpumask_test_cpu(cpu, newdev->cpumask))
251 return false;
252 if (cpumask_equal(newdev->cpumask, cpumask_of(cpu)))
253 return true;
254 /* Check if irq affinity can be set */
255 if (newdev->irq >= 0 && !irq_can_set_affinity(newdev->irq))
256 return false;
257 /* Prefer an existing cpu local device */
258 if (curdev && cpumask_equal(curdev->cpumask, cpumask_of(cpu)))
259 return false;
260 return true;
261}
262
263static bool tick_check_preferred(struct clock_event_device *curdev,
264 struct clock_event_device *newdev)
265{
266 /* Prefer oneshot capable device */
267 if (!(newdev->features & CLOCK_EVT_FEAT_ONESHOT)) {
268 if (curdev && (curdev->features & CLOCK_EVT_FEAT_ONESHOT))
269 return false;
270 if (tick_oneshot_mode_active())
271 return false;
272 }
273
274 /*
275 * Use the higher rated one, but prefer a CPU local device with a lower
276 * rating than a non-CPU local device
277 */
278 return !curdev ||
279 newdev->rating > curdev->rating ||
280 !cpumask_equal(curdev->cpumask, newdev->cpumask);
281}
282
283/*
284 * Check whether the new device is a better fit than curdev. curdev
285 * can be NULL !
286 */
287bool tick_check_replacement(struct clock_event_device *curdev,
288 struct clock_event_device *newdev)
289{
290 if (!tick_check_percpu(curdev, newdev, smp_processor_id()))
291 return false;
292
293 return tick_check_preferred(curdev, newdev);
294}
295
296/*
297 * Check, if the new registered device should be used. Called with
298 * clockevents_lock held and interrupts disabled.
299 */
300void tick_check_new_device(struct clock_event_device *newdev)
301{
302 struct clock_event_device *curdev;
303 struct tick_device *td;
304 int cpu;
305
306 cpu = smp_processor_id();
307 td = &per_cpu(tick_cpu_device, cpu);
308 curdev = td->evtdev;
309
310 /* cpu local device ? */
311 if (!tick_check_percpu(curdev, newdev, cpu))
312 goto out_bc;
313
314 /* Preference decision */
315 if (!tick_check_preferred(curdev, newdev))
316 goto out_bc;
317
318 if (!try_module_get(newdev->owner))
319 return;
320
321 /*
322 * Replace the eventually existing device by the new
323 * device. If the current device is the broadcast device, do
324 * not give it back to the clockevents layer !
325 */
326 if (tick_is_broadcast_device(curdev)) {
327 clockevents_shutdown(curdev);
328 curdev = NULL;
329 }
330 clockevents_exchange_device(curdev, newdev);
331 tick_setup_device(td, newdev, cpu, cpumask_of(cpu));
332 if (newdev->features & CLOCK_EVT_FEAT_ONESHOT)
333 tick_oneshot_notify();
334 return;
335
336out_bc:
337 /*
338 * Can the new device be used as a broadcast device ?
339 */
340 tick_install_broadcast_device(newdev);
341}
342
343/**
344 * tick_broadcast_oneshot_control - Enter/exit broadcast oneshot mode
345 * @state: The target state (enter/exit)
346 *
347 * The system enters/leaves a state, where affected devices might stop
348 * Returns 0 on success, -EBUSY if the cpu is used to broadcast wakeups.
349 *
350 * Called with interrupts disabled, so clockevents_lock is not
351 * required here because the local clock event device cannot go away
352 * under us.
353 */
354int tick_broadcast_oneshot_control(enum tick_broadcast_state state)
355{
356 struct tick_device *td = this_cpu_ptr(&tick_cpu_device);
357
358 if (!(td->evtdev->features & CLOCK_EVT_FEAT_C3STOP))
359 return 0;
360
361 return __tick_broadcast_oneshot_control(state);
362}
363EXPORT_SYMBOL_GPL(tick_broadcast_oneshot_control);
364
365#ifdef CONFIG_HOTPLUG_CPU
366/*
367 * Transfer the do_timer job away from a dying cpu.
368 *
369 * Called with interrupts disabled. Not locking required. If
370 * tick_do_timer_cpu is owned by this cpu, nothing can change it.
371 */
372void tick_handover_do_timer(void)
373{
374 if (tick_do_timer_cpu == smp_processor_id()) {
375 int cpu = cpumask_first(cpu_online_mask);
376
377 tick_do_timer_cpu = (cpu < nr_cpu_ids) ? cpu :
378 TICK_DO_TIMER_NONE;
379 }
380}
381
382/*
383 * Shutdown an event device on a given cpu:
384 *
385 * This is called on a life CPU, when a CPU is dead. So we cannot
386 * access the hardware device itself.
387 * We just set the mode and remove it from the lists.
388 */
389void tick_shutdown(unsigned int cpu)
390{
391 struct tick_device *td = &per_cpu(tick_cpu_device, cpu);
392 struct clock_event_device *dev = td->evtdev;
393
394 td->mode = TICKDEV_MODE_PERIODIC;
395 if (dev) {
396 /*
397 * Prevent that the clock events layer tries to call
398 * the set mode function!
399 */
400 clockevent_set_state(dev, CLOCK_EVT_STATE_DETACHED);
401 clockevents_exchange_device(dev, NULL);
402 dev->event_handler = clockevents_handle_noop;
403 td->evtdev = NULL;
404 }
405}
406#endif
407
408/**
409 * tick_suspend_local - Suspend the local tick device
410 *
411 * Called from the local cpu for freeze with interrupts disabled.
412 *
413 * No locks required. Nothing can change the per cpu device.
414 */
415void tick_suspend_local(void)
416{
417 struct tick_device *td = this_cpu_ptr(&tick_cpu_device);
418
419 clockevents_shutdown(td->evtdev);
420}
421
422/**
423 * tick_resume_local - Resume the local tick device
424 *
425 * Called from the local CPU for unfreeze or XEN resume magic.
426 *
427 * No locks required. Nothing can change the per cpu device.
428 */
429void tick_resume_local(void)
430{
431 struct tick_device *td = this_cpu_ptr(&tick_cpu_device);
432 bool broadcast = tick_resume_check_broadcast();
433
434 clockevents_tick_resume(td->evtdev);
435 if (!broadcast) {
436 if (td->mode == TICKDEV_MODE_PERIODIC)
437 tick_setup_periodic(td->evtdev, 0);
438 else
439 tick_resume_oneshot();
440 }
441}
442
443/**
444 * tick_suspend - Suspend the tick and the broadcast device
445 *
446 * Called from syscore_suspend() via timekeeping_suspend with only one
447 * CPU online and interrupts disabled or from tick_unfreeze() under
448 * tick_freeze_lock.
449 *
450 * No locks required. Nothing can change the per cpu device.
451 */
452void tick_suspend(void)
453{
454 tick_suspend_local();
455 tick_suspend_broadcast();
456}
457
458/**
459 * tick_resume - Resume the tick and the broadcast device
460 *
461 * Called from syscore_resume() via timekeeping_resume with only one
462 * CPU online and interrupts disabled.
463 *
464 * No locks required. Nothing can change the per cpu device.
465 */
466void tick_resume(void)
467{
468 tick_resume_broadcast();
469 tick_resume_local();
470}
471
472#ifdef CONFIG_SUSPEND
473static DEFINE_RAW_SPINLOCK(tick_freeze_lock);
474static unsigned int tick_freeze_depth;
475
476/**
477 * tick_freeze - Suspend the local tick and (possibly) timekeeping.
478 *
479 * Check if this is the last online CPU executing the function and if so,
480 * suspend timekeeping. Otherwise suspend the local tick.
481 *
482 * Call with interrupts disabled. Must be balanced with %tick_unfreeze().
483 * Interrupts must not be enabled before the subsequent %tick_unfreeze().
484 */
485void tick_freeze(void)
486{
487 raw_spin_lock(&tick_freeze_lock);
488
489 tick_freeze_depth++;
490 if (tick_freeze_depth == num_online_cpus()) {
491 trace_suspend_resume(TPS("timekeeping_freeze"),
492 smp_processor_id(), true);
493 timekeeping_suspend();
494 } else {
495 tick_suspend_local();
496 }
497
498 raw_spin_unlock(&tick_freeze_lock);
499}
500
501/**
502 * tick_unfreeze - Resume the local tick and (possibly) timekeeping.
503 *
504 * Check if this is the first CPU executing the function and if so, resume
505 * timekeeping. Otherwise resume the local tick.
506 *
507 * Call with interrupts disabled. Must be balanced with %tick_freeze().
508 * Interrupts must not be enabled after the preceding %tick_freeze().
509 */
510void tick_unfreeze(void)
511{
512 raw_spin_lock(&tick_freeze_lock);
513
514 if (tick_freeze_depth == num_online_cpus()) {
515 timekeeping_resume();
516 trace_suspend_resume(TPS("timekeeping_freeze"),
517 smp_processor_id(), false);
518 } else {
519 tick_resume_local();
520 }
521
522 tick_freeze_depth--;
523
524 raw_spin_unlock(&tick_freeze_lock);
525}
526#endif /* CONFIG_SUSPEND */
527
528/**
529 * tick_init - initialize the tick control
530 */
531void __init tick_init(void)
532{
533 tick_broadcast_init();
534 tick_nohz_init();
535}
1// SPDX-License-Identifier: GPL-2.0
2/*
3 * This file contains the base functions to manage periodic tick
4 * related events.
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/nmi.h>
15#include <linux/percpu.h>
16#include <linux/profile.h>
17#include <linux/sched.h>
18#include <linux/module.h>
19#include <trace/events/power.h>
20
21#include <asm/irq_regs.h>
22
23#include "tick-internal.h"
24
25/*
26 * Tick devices
27 */
28DEFINE_PER_CPU(struct tick_device, tick_cpu_device);
29/*
30 * Tick next event: keeps track of the tick time. It's updated by the
31 * CPU which handles the tick and protected by jiffies_lock. There is
32 * no requirement to write hold the jiffies seqcount for it.
33 */
34ktime_t tick_next_period;
35
36/*
37 * tick_do_timer_cpu is a timer core internal variable which holds the CPU NR
38 * which is responsible for calling do_timer(), i.e. the timekeeping stuff. This
39 * variable has two functions:
40 *
41 * 1) Prevent a thundering herd issue of a gazillion of CPUs trying to grab the
42 * timekeeping lock all at once. Only the CPU which is assigned to do the
43 * update is handling it.
44 *
45 * 2) Hand off the duty in the NOHZ idle case by setting the value to
46 * TICK_DO_TIMER_NONE, i.e. a non existing CPU. So the next cpu which looks
47 * at it will take over and keep the time keeping alive. The handover
48 * procedure also covers cpu hotplug.
49 */
50int tick_do_timer_cpu __read_mostly = TICK_DO_TIMER_BOOT;
51#ifdef CONFIG_NO_HZ_FULL
52/*
53 * tick_do_timer_boot_cpu indicates the boot CPU temporarily owns
54 * tick_do_timer_cpu and it should be taken over by an eligible secondary
55 * when one comes online.
56 */
57static int tick_do_timer_boot_cpu __read_mostly = -1;
58#endif
59
60/*
61 * Debugging: see timer_list.c
62 */
63struct tick_device *tick_get_device(int cpu)
64{
65 return &per_cpu(tick_cpu_device, cpu);
66}
67
68/**
69 * tick_is_oneshot_available - check for a oneshot capable event device
70 */
71int tick_is_oneshot_available(void)
72{
73 struct clock_event_device *dev = __this_cpu_read(tick_cpu_device.evtdev);
74
75 if (!dev || !(dev->features & CLOCK_EVT_FEAT_ONESHOT))
76 return 0;
77 if (!(dev->features & CLOCK_EVT_FEAT_C3STOP))
78 return 1;
79 return tick_broadcast_oneshot_available();
80}
81
82/*
83 * Periodic tick
84 */
85static void tick_periodic(int cpu)
86{
87 if (tick_do_timer_cpu == cpu) {
88 raw_spin_lock(&jiffies_lock);
89 write_seqcount_begin(&jiffies_seq);
90
91 /* Keep track of the next tick event */
92 tick_next_period = ktime_add_ns(tick_next_period, TICK_NSEC);
93
94 do_timer(1);
95 write_seqcount_end(&jiffies_seq);
96 raw_spin_unlock(&jiffies_lock);
97 update_wall_time();
98 }
99
100 update_process_times(user_mode(get_irq_regs()));
101 profile_tick(CPU_PROFILING);
102}
103
104/*
105 * Event handler for periodic ticks
106 */
107void tick_handle_periodic(struct clock_event_device *dev)
108{
109 int cpu = smp_processor_id();
110 ktime_t next = dev->next_event;
111
112 tick_periodic(cpu);
113
114#if defined(CONFIG_HIGH_RES_TIMERS) || defined(CONFIG_NO_HZ_COMMON)
115 /*
116 * The cpu might have transitioned to HIGHRES or NOHZ mode via
117 * update_process_times() -> run_local_timers() ->
118 * hrtimer_run_queues().
119 */
120 if (dev->event_handler != tick_handle_periodic)
121 return;
122#endif
123
124 if (!clockevent_state_oneshot(dev))
125 return;
126 for (;;) {
127 /*
128 * Setup the next period for devices, which do not have
129 * periodic mode:
130 */
131 next = ktime_add_ns(next, TICK_NSEC);
132
133 if (!clockevents_program_event(dev, next, false))
134 return;
135 /*
136 * Have to be careful here. If we're in oneshot mode,
137 * before we call tick_periodic() in a loop, we need
138 * to be sure we're using a real hardware clocksource.
139 * Otherwise we could get trapped in an infinite
140 * loop, as the tick_periodic() increments jiffies,
141 * which then will increment time, possibly causing
142 * the loop to trigger again and again.
143 */
144 if (timekeeping_valid_for_hres())
145 tick_periodic(cpu);
146 }
147}
148
149/*
150 * Setup the device for a periodic tick
151 */
152void tick_setup_periodic(struct clock_event_device *dev, int broadcast)
153{
154 tick_set_periodic_handler(dev, broadcast);
155
156 /* Broadcast setup ? */
157 if (!tick_device_is_functional(dev))
158 return;
159
160 if ((dev->features & CLOCK_EVT_FEAT_PERIODIC) &&
161 !tick_broadcast_oneshot_active()) {
162 clockevents_switch_state(dev, CLOCK_EVT_STATE_PERIODIC);
163 } else {
164 unsigned int seq;
165 ktime_t next;
166
167 do {
168 seq = read_seqcount_begin(&jiffies_seq);
169 next = tick_next_period;
170 } while (read_seqcount_retry(&jiffies_seq, seq));
171
172 clockevents_switch_state(dev, CLOCK_EVT_STATE_ONESHOT);
173
174 for (;;) {
175 if (!clockevents_program_event(dev, next, false))
176 return;
177 next = ktime_add_ns(next, TICK_NSEC);
178 }
179 }
180}
181
182#ifdef CONFIG_NO_HZ_FULL
183static void giveup_do_timer(void *info)
184{
185 int cpu = *(unsigned int *)info;
186
187 WARN_ON(tick_do_timer_cpu != smp_processor_id());
188
189 tick_do_timer_cpu = cpu;
190}
191
192static void tick_take_do_timer_from_boot(void)
193{
194 int cpu = smp_processor_id();
195 int from = tick_do_timer_boot_cpu;
196
197 if (from >= 0 && from != cpu)
198 smp_call_function_single(from, giveup_do_timer, &cpu, 1);
199}
200#endif
201
202/*
203 * Setup the tick device
204 */
205static void tick_setup_device(struct tick_device *td,
206 struct clock_event_device *newdev, int cpu,
207 const struct cpumask *cpumask)
208{
209 void (*handler)(struct clock_event_device *) = NULL;
210 ktime_t next_event = 0;
211
212 /*
213 * First device setup ?
214 */
215 if (!td->evtdev) {
216 /*
217 * If no cpu took the do_timer update, assign it to
218 * this cpu:
219 */
220 if (tick_do_timer_cpu == TICK_DO_TIMER_BOOT) {
221 tick_do_timer_cpu = cpu;
222 tick_next_period = ktime_get();
223#ifdef CONFIG_NO_HZ_FULL
224 /*
225 * The boot CPU may be nohz_full, in which case set
226 * tick_do_timer_boot_cpu so the first housekeeping
227 * secondary that comes up will take do_timer from
228 * us.
229 */
230 if (tick_nohz_full_cpu(cpu))
231 tick_do_timer_boot_cpu = cpu;
232
233 } else if (tick_do_timer_boot_cpu != -1 &&
234 !tick_nohz_full_cpu(cpu)) {
235 tick_take_do_timer_from_boot();
236 tick_do_timer_boot_cpu = -1;
237 WARN_ON(tick_do_timer_cpu != cpu);
238#endif
239 }
240
241 /*
242 * Startup in periodic mode first.
243 */
244 td->mode = TICKDEV_MODE_PERIODIC;
245 } else {
246 handler = td->evtdev->event_handler;
247 next_event = td->evtdev->next_event;
248 td->evtdev->event_handler = clockevents_handle_noop;
249 }
250
251 td->evtdev = newdev;
252
253 /*
254 * When the device is not per cpu, pin the interrupt to the
255 * current cpu:
256 */
257 if (!cpumask_equal(newdev->cpumask, cpumask))
258 irq_set_affinity(newdev->irq, cpumask);
259
260 /*
261 * When global broadcasting is active, check if the current
262 * device is registered as a placeholder for broadcast mode.
263 * This allows us to handle this x86 misfeature in a generic
264 * way. This function also returns !=0 when we keep the
265 * current active broadcast state for this CPU.
266 */
267 if (tick_device_uses_broadcast(newdev, cpu))
268 return;
269
270 if (td->mode == TICKDEV_MODE_PERIODIC)
271 tick_setup_periodic(newdev, 0);
272 else
273 tick_setup_oneshot(newdev, handler, next_event);
274}
275
276void tick_install_replacement(struct clock_event_device *newdev)
277{
278 struct tick_device *td = this_cpu_ptr(&tick_cpu_device);
279 int cpu = smp_processor_id();
280
281 clockevents_exchange_device(td->evtdev, newdev);
282 tick_setup_device(td, newdev, cpu, cpumask_of(cpu));
283 if (newdev->features & CLOCK_EVT_FEAT_ONESHOT)
284 tick_oneshot_notify();
285}
286
287static bool tick_check_percpu(struct clock_event_device *curdev,
288 struct clock_event_device *newdev, int cpu)
289{
290 if (!cpumask_test_cpu(cpu, newdev->cpumask))
291 return false;
292 if (cpumask_equal(newdev->cpumask, cpumask_of(cpu)))
293 return true;
294 /* Check if irq affinity can be set */
295 if (newdev->irq >= 0 && !irq_can_set_affinity(newdev->irq))
296 return false;
297 /* Prefer an existing cpu local device */
298 if (curdev && cpumask_equal(curdev->cpumask, cpumask_of(cpu)))
299 return false;
300 return true;
301}
302
303static bool tick_check_preferred(struct clock_event_device *curdev,
304 struct clock_event_device *newdev)
305{
306 /* Prefer oneshot capable device */
307 if (!(newdev->features & CLOCK_EVT_FEAT_ONESHOT)) {
308 if (curdev && (curdev->features & CLOCK_EVT_FEAT_ONESHOT))
309 return false;
310 if (tick_oneshot_mode_active())
311 return false;
312 }
313
314 /*
315 * Use the higher rated one, but prefer a CPU local device with a lower
316 * rating than a non-CPU local device
317 */
318 return !curdev ||
319 newdev->rating > curdev->rating ||
320 !cpumask_equal(curdev->cpumask, newdev->cpumask);
321}
322
323/*
324 * Check whether the new device is a better fit than curdev. curdev
325 * can be NULL !
326 */
327bool tick_check_replacement(struct clock_event_device *curdev,
328 struct clock_event_device *newdev)
329{
330 if (!tick_check_percpu(curdev, newdev, smp_processor_id()))
331 return false;
332
333 return tick_check_preferred(curdev, newdev);
334}
335
336/*
337 * Check, if the new registered device should be used. Called with
338 * clockevents_lock held and interrupts disabled.
339 */
340void tick_check_new_device(struct clock_event_device *newdev)
341{
342 struct clock_event_device *curdev;
343 struct tick_device *td;
344 int cpu;
345
346 cpu = smp_processor_id();
347 td = &per_cpu(tick_cpu_device, cpu);
348 curdev = td->evtdev;
349
350 if (!tick_check_replacement(curdev, newdev))
351 goto out_bc;
352
353 if (!try_module_get(newdev->owner))
354 return;
355
356 /*
357 * Replace the eventually existing device by the new
358 * device. If the current device is the broadcast device, do
359 * not give it back to the clockevents layer !
360 */
361 if (tick_is_broadcast_device(curdev)) {
362 clockevents_shutdown(curdev);
363 curdev = NULL;
364 }
365 clockevents_exchange_device(curdev, newdev);
366 tick_setup_device(td, newdev, cpu, cpumask_of(cpu));
367 if (newdev->features & CLOCK_EVT_FEAT_ONESHOT)
368 tick_oneshot_notify();
369 return;
370
371out_bc:
372 /*
373 * Can the new device be used as a broadcast device ?
374 */
375 tick_install_broadcast_device(newdev, cpu);
376}
377
378/**
379 * tick_broadcast_oneshot_control - Enter/exit broadcast oneshot mode
380 * @state: The target state (enter/exit)
381 *
382 * The system enters/leaves a state, where affected devices might stop
383 * Returns 0 on success, -EBUSY if the cpu is used to broadcast wakeups.
384 *
385 * Called with interrupts disabled, so clockevents_lock is not
386 * required here because the local clock event device cannot go away
387 * under us.
388 */
389int tick_broadcast_oneshot_control(enum tick_broadcast_state state)
390{
391 struct tick_device *td = this_cpu_ptr(&tick_cpu_device);
392
393 if (!(td->evtdev->features & CLOCK_EVT_FEAT_C3STOP))
394 return 0;
395
396 return __tick_broadcast_oneshot_control(state);
397}
398EXPORT_SYMBOL_GPL(tick_broadcast_oneshot_control);
399
400#ifdef CONFIG_HOTPLUG_CPU
401/*
402 * Transfer the do_timer job away from a dying cpu.
403 *
404 * Called with interrupts disabled. No locking required. If
405 * tick_do_timer_cpu is owned by this cpu, nothing can change it.
406 */
407void tick_handover_do_timer(void)
408{
409 if (tick_do_timer_cpu == smp_processor_id())
410 tick_do_timer_cpu = cpumask_first(cpu_online_mask);
411}
412
413/*
414 * Shutdown an event device on a given cpu:
415 *
416 * This is called on a life CPU, when a CPU is dead. So we cannot
417 * access the hardware device itself.
418 * We just set the mode and remove it from the lists.
419 */
420void tick_shutdown(unsigned int cpu)
421{
422 struct tick_device *td = &per_cpu(tick_cpu_device, cpu);
423 struct clock_event_device *dev = td->evtdev;
424
425 td->mode = TICKDEV_MODE_PERIODIC;
426 if (dev) {
427 /*
428 * Prevent that the clock events layer tries to call
429 * the set mode function!
430 */
431 clockevent_set_state(dev, CLOCK_EVT_STATE_DETACHED);
432 clockevents_exchange_device(dev, NULL);
433 dev->event_handler = clockevents_handle_noop;
434 td->evtdev = NULL;
435 }
436}
437#endif
438
439/**
440 * tick_suspend_local - Suspend the local tick device
441 *
442 * Called from the local cpu for freeze with interrupts disabled.
443 *
444 * No locks required. Nothing can change the per cpu device.
445 */
446void tick_suspend_local(void)
447{
448 struct tick_device *td = this_cpu_ptr(&tick_cpu_device);
449
450 clockevents_shutdown(td->evtdev);
451}
452
453/**
454 * tick_resume_local - Resume the local tick device
455 *
456 * Called from the local CPU for unfreeze or XEN resume magic.
457 *
458 * No locks required. Nothing can change the per cpu device.
459 */
460void tick_resume_local(void)
461{
462 struct tick_device *td = this_cpu_ptr(&tick_cpu_device);
463 bool broadcast = tick_resume_check_broadcast();
464
465 clockevents_tick_resume(td->evtdev);
466 if (!broadcast) {
467 if (td->mode == TICKDEV_MODE_PERIODIC)
468 tick_setup_periodic(td->evtdev, 0);
469 else
470 tick_resume_oneshot();
471 }
472
473 /*
474 * Ensure that hrtimers are up to date and the clockevents device
475 * is reprogrammed correctly when high resolution timers are
476 * enabled.
477 */
478 hrtimers_resume_local();
479}
480
481/**
482 * tick_suspend - Suspend the tick and the broadcast device
483 *
484 * Called from syscore_suspend() via timekeeping_suspend with only one
485 * CPU online and interrupts disabled or from tick_unfreeze() under
486 * tick_freeze_lock.
487 *
488 * No locks required. Nothing can change the per cpu device.
489 */
490void tick_suspend(void)
491{
492 tick_suspend_local();
493 tick_suspend_broadcast();
494}
495
496/**
497 * tick_resume - Resume the tick and the broadcast device
498 *
499 * Called from syscore_resume() via timekeeping_resume with only one
500 * CPU online and interrupts disabled.
501 *
502 * No locks required. Nothing can change the per cpu device.
503 */
504void tick_resume(void)
505{
506 tick_resume_broadcast();
507 tick_resume_local();
508}
509
510#ifdef CONFIG_SUSPEND
511static DEFINE_RAW_SPINLOCK(tick_freeze_lock);
512static unsigned int tick_freeze_depth;
513
514/**
515 * tick_freeze - Suspend the local tick and (possibly) timekeeping.
516 *
517 * Check if this is the last online CPU executing the function and if so,
518 * suspend timekeeping. Otherwise suspend the local tick.
519 *
520 * Call with interrupts disabled. Must be balanced with %tick_unfreeze().
521 * Interrupts must not be enabled before the subsequent %tick_unfreeze().
522 */
523void tick_freeze(void)
524{
525 raw_spin_lock(&tick_freeze_lock);
526
527 tick_freeze_depth++;
528 if (tick_freeze_depth == num_online_cpus()) {
529 trace_suspend_resume(TPS("timekeeping_freeze"),
530 smp_processor_id(), true);
531 system_state = SYSTEM_SUSPEND;
532 sched_clock_suspend();
533 timekeeping_suspend();
534 } else {
535 tick_suspend_local();
536 }
537
538 raw_spin_unlock(&tick_freeze_lock);
539}
540
541/**
542 * tick_unfreeze - Resume the local tick and (possibly) timekeeping.
543 *
544 * Check if this is the first CPU executing the function and if so, resume
545 * timekeeping. Otherwise resume the local tick.
546 *
547 * Call with interrupts disabled. Must be balanced with %tick_freeze().
548 * Interrupts must not be enabled after the preceding %tick_freeze().
549 */
550void tick_unfreeze(void)
551{
552 raw_spin_lock(&tick_freeze_lock);
553
554 if (tick_freeze_depth == num_online_cpus()) {
555 timekeeping_resume();
556 sched_clock_resume();
557 system_state = SYSTEM_RUNNING;
558 trace_suspend_resume(TPS("timekeeping_freeze"),
559 smp_processor_id(), false);
560 } else {
561 touch_softlockup_watchdog();
562 tick_resume_local();
563 }
564
565 tick_freeze_depth--;
566
567 raw_spin_unlock(&tick_freeze_lock);
568}
569#endif /* CONFIG_SUSPEND */
570
571/**
572 * tick_init - initialize the tick control
573 */
574void __init tick_init(void)
575{
576 tick_broadcast_init();
577 tick_nohz_init();
578}