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35728b82 | 1 | // SPDX-License-Identifier: GPL-2.0 |
906568c9 | 2 | /* |
906568c9 TG |
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 | |
906568c9 TG |
9 | */ |
10 | #include <linux/cpu.h> | |
11 | #include <linux/err.h> | |
12 | #include <linux/hrtimer.h> | |
d7b90689 | 13 | #include <linux/interrupt.h> |
5167c506 | 14 | #include <linux/nmi.h> |
906568c9 TG |
15 | #include <linux/percpu.h> |
16 | #include <linux/profile.h> | |
17 | #include <linux/sched.h> | |
ccf33d68 | 18 | #include <linux/module.h> |
75e0678e | 19 | #include <trace/events/power.h> |
906568c9 | 20 | |
d7b90689 RK |
21 | #include <asm/irq_regs.h> |
22 | ||
f8381cba TG |
23 | #include "tick-internal.h" |
24 | ||
906568c9 TG |
25 | /* |
26 | * Tick devices | |
27 | */ | |
f8381cba | 28 | DEFINE_PER_CPU(struct tick_device, tick_cpu_device); |
906568c9 | 29 | /* |
c398960c TG |
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. | |
906568c9 | 33 | */ |
f8381cba | 34 | ktime_t tick_next_period; |
050ded1b AM |
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 | */ | |
6441402b | 50 | int tick_do_timer_cpu __read_mostly = TICK_DO_TIMER_BOOT; |
08ae95f4 NP |
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 | */ | |
57 | static int tick_do_timer_boot_cpu __read_mostly = -1; | |
58 | #endif | |
906568c9 | 59 | |
289f480a IM |
60 | /* |
61 | * Debugging: see timer_list.c | |
62 | */ | |
63 | struct tick_device *tick_get_device(int cpu) | |
64 | { | |
65 | return &per_cpu(tick_cpu_device, cpu); | |
66 | } | |
67 | ||
79bf2bb3 TG |
68 | /** |
69 | * tick_is_oneshot_available - check for a oneshot capable event device | |
70 | */ | |
71 | int tick_is_oneshot_available(void) | |
72 | { | |
909ea964 | 73 | struct clock_event_device *dev = __this_cpu_read(tick_cpu_device.evtdev); |
79bf2bb3 | 74 | |
3a142a06 TG |
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(); | |
79bf2bb3 TG |
80 | } |
81 | ||
906568c9 TG |
82 | /* |
83 | * Periodic tick | |
84 | */ | |
85 | static void tick_periodic(int cpu) | |
86 | { | |
87 | if (tick_do_timer_cpu == cpu) { | |
e5d4d175 TG |
88 | raw_spin_lock(&jiffies_lock); |
89 | write_seqcount_begin(&jiffies_seq); | |
906568c9 TG |
90 | |
91 | /* Keep track of the next tick event */ | |
b9965449 | 92 | tick_next_period = ktime_add_ns(tick_next_period, TICK_NSEC); |
906568c9 TG |
93 | |
94 | do_timer(1); | |
e5d4d175 TG |
95 | write_seqcount_end(&jiffies_seq); |
96 | raw_spin_unlock(&jiffies_lock); | |
47a1b796 | 97 | update_wall_time(); |
906568c9 TG |
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 | */ | |
107 | void tick_handle_periodic(struct clock_event_device *dev) | |
108 | { | |
109 | int cpu = smp_processor_id(); | |
b97f0291 | 110 | ktime_t next = dev->next_event; |
906568c9 TG |
111 | |
112 | tick_periodic(cpu); | |
113 | ||
c6eb3f70 TG |
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 | ||
472c4a94 | 124 | if (!clockevent_state_oneshot(dev)) |
906568c9 | 125 | return; |
906568c9 | 126 | for (;;) { |
b97f0291 VK |
127 | /* |
128 | * Setup the next period for devices, which do not have | |
129 | * periodic mode: | |
130 | */ | |
b9965449 | 131 | next = ktime_add_ns(next, TICK_NSEC); |
b97f0291 | 132 | |
d1748302 | 133 | if (!clockevents_program_event(dev, next, false)) |
906568c9 | 134 | return; |
74a03b69 | 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, | |
cacb3c76 | 141 | * which then will increment time, possibly causing |
74a03b69 | 142 | * the loop to trigger again and again. |
143 | */ | |
144 | if (timekeeping_valid_for_hres()) | |
145 | tick_periodic(cpu); | |
906568c9 TG |
146 | } |
147 | } | |
148 | ||
149 | /* | |
150 | * Setup the device for a periodic tick | |
151 | */ | |
f8381cba | 152 | void tick_setup_periodic(struct clock_event_device *dev, int broadcast) |
906568c9 | 153 | { |
f8381cba TG |
154 | tick_set_periodic_handler(dev, broadcast); |
155 | ||
156 | /* Broadcast setup ? */ | |
157 | if (!tick_device_is_functional(dev)) | |
158 | return; | |
906568c9 | 159 | |
27ce4cb4 TG |
160 | if ((dev->features & CLOCK_EVT_FEAT_PERIODIC) && |
161 | !tick_broadcast_oneshot_active()) { | |
d7eb231c | 162 | clockevents_switch_state(dev, CLOCK_EVT_STATE_PERIODIC); |
906568c9 | 163 | } else { |
e1e41b6c | 164 | unsigned int seq; |
906568c9 TG |
165 | ktime_t next; |
166 | ||
167 | do { | |
e5d4d175 | 168 | seq = read_seqcount_begin(&jiffies_seq); |
906568c9 | 169 | next = tick_next_period; |
e5d4d175 | 170 | } while (read_seqcount_retry(&jiffies_seq, seq)); |
906568c9 | 171 | |
d7eb231c | 172 | clockevents_switch_state(dev, CLOCK_EVT_STATE_ONESHOT); |
906568c9 TG |
173 | |
174 | for (;;) { | |
d1748302 | 175 | if (!clockevents_program_event(dev, next, false)) |
906568c9 | 176 | return; |
b9965449 | 177 | next = ktime_add_ns(next, TICK_NSEC); |
906568c9 TG |
178 | } |
179 | } | |
180 | } | |
181 | ||
08ae95f4 NP |
182 | #ifdef CONFIG_NO_HZ_FULL |
183 | static 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 | ||
192 | static 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 | ||
906568c9 TG |
202 | /* |
203 | * Setup the tick device | |
204 | */ | |
205 | static void tick_setup_device(struct tick_device *td, | |
206 | struct clock_event_device *newdev, int cpu, | |
0de26520 | 207 | const struct cpumask *cpumask) |
906568c9 | 208 | { |
906568c9 | 209 | void (*handler)(struct clock_event_device *) = NULL; |
8b0e1953 | 210 | ktime_t next_event = 0; |
906568c9 TG |
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 | */ | |
6441402b | 220 | if (tick_do_timer_cpu == TICK_DO_TIMER_BOOT) { |
e9523a0d SAS |
221 | ktime_t next_p; |
222 | u32 rem; | |
223 | ||
08ae95f4 NP |
224 | tick_do_timer_cpu = cpu; |
225 | ||
e9523a0d SAS |
226 | next_p = ktime_get(); |
227 | div_u64_rem(next_p, TICK_NSEC, &rem); | |
228 | if (rem) { | |
229 | next_p -= rem; | |
230 | next_p += TICK_NSEC; | |
231 | } | |
232 | ||
233 | tick_next_period = next_p; | |
08ae95f4 NP |
234 | #ifdef CONFIG_NO_HZ_FULL |
235 | /* | |
236 | * The boot CPU may be nohz_full, in which case set | |
237 | * tick_do_timer_boot_cpu so the first housekeeping | |
238 | * secondary that comes up will take do_timer from | |
239 | * us. | |
240 | */ | |
241 | if (tick_nohz_full_cpu(cpu)) | |
242 | tick_do_timer_boot_cpu = cpu; | |
243 | ||
244 | } else if (tick_do_timer_boot_cpu != -1 && | |
245 | !tick_nohz_full_cpu(cpu)) { | |
246 | tick_take_do_timer_from_boot(); | |
247 | tick_do_timer_boot_cpu = -1; | |
248 | WARN_ON(tick_do_timer_cpu != cpu); | |
249 | #endif | |
906568c9 TG |
250 | } |
251 | ||
252 | /* | |
253 | * Startup in periodic mode first. | |
254 | */ | |
255 | td->mode = TICKDEV_MODE_PERIODIC; | |
256 | } else { | |
257 | handler = td->evtdev->event_handler; | |
258 | next_event = td->evtdev->next_event; | |
7c1e7689 | 259 | td->evtdev->event_handler = clockevents_handle_noop; |
906568c9 TG |
260 | } |
261 | ||
262 | td->evtdev = newdev; | |
263 | ||
264 | /* | |
265 | * When the device is not per cpu, pin the interrupt to the | |
266 | * current cpu: | |
267 | */ | |
320ab2b0 | 268 | if (!cpumask_equal(newdev->cpumask, cpumask)) |
0de26520 | 269 | irq_set_affinity(newdev->irq, cpumask); |
906568c9 | 270 | |
f8381cba TG |
271 | /* |
272 | * When global broadcasting is active, check if the current | |
273 | * device is registered as a placeholder for broadcast mode. | |
274 | * This allows us to handle this x86 misfeature in a generic | |
07bd1172 TG |
275 | * way. This function also returns !=0 when we keep the |
276 | * current active broadcast state for this CPU. | |
f8381cba TG |
277 | */ |
278 | if (tick_device_uses_broadcast(newdev, cpu)) | |
279 | return; | |
280 | ||
906568c9 TG |
281 | if (td->mode == TICKDEV_MODE_PERIODIC) |
282 | tick_setup_periodic(newdev, 0); | |
79bf2bb3 TG |
283 | else |
284 | tick_setup_oneshot(newdev, handler, next_event); | |
906568c9 TG |
285 | } |
286 | ||
03e13cf5 TG |
287 | void tick_install_replacement(struct clock_event_device *newdev) |
288 | { | |
22127e93 | 289 | struct tick_device *td = this_cpu_ptr(&tick_cpu_device); |
03e13cf5 TG |
290 | int cpu = smp_processor_id(); |
291 | ||
292 | clockevents_exchange_device(td->evtdev, newdev); | |
293 | tick_setup_device(td, newdev, cpu, cpumask_of(cpu)); | |
294 | if (newdev->features & CLOCK_EVT_FEAT_ONESHOT) | |
295 | tick_oneshot_notify(); | |
296 | } | |
297 | ||
45cb8e01 TG |
298 | static bool tick_check_percpu(struct clock_event_device *curdev, |
299 | struct clock_event_device *newdev, int cpu) | |
300 | { | |
301 | if (!cpumask_test_cpu(cpu, newdev->cpumask)) | |
302 | return false; | |
303 | if (cpumask_equal(newdev->cpumask, cpumask_of(cpu))) | |
304 | return true; | |
305 | /* Check if irq affinity can be set */ | |
306 | if (newdev->irq >= 0 && !irq_can_set_affinity(newdev->irq)) | |
307 | return false; | |
308 | /* Prefer an existing cpu local device */ | |
309 | if (curdev && cpumask_equal(curdev->cpumask, cpumask_of(cpu))) | |
310 | return false; | |
311 | return true; | |
312 | } | |
313 | ||
314 | static bool tick_check_preferred(struct clock_event_device *curdev, | |
315 | struct clock_event_device *newdev) | |
316 | { | |
317 | /* Prefer oneshot capable device */ | |
318 | if (!(newdev->features & CLOCK_EVT_FEAT_ONESHOT)) { | |
319 | if (curdev && (curdev->features & CLOCK_EVT_FEAT_ONESHOT)) | |
320 | return false; | |
321 | if (tick_oneshot_mode_active()) | |
322 | return false; | |
323 | } | |
324 | ||
70e5975d SB |
325 | /* |
326 | * Use the higher rated one, but prefer a CPU local device with a lower | |
327 | * rating than a non-CPU local device | |
328 | */ | |
329 | return !curdev || | |
330 | newdev->rating > curdev->rating || | |
5b5ccbc2 | 331 | !cpumask_equal(curdev->cpumask, newdev->cpumask); |
45cb8e01 TG |
332 | } |
333 | ||
03e13cf5 TG |
334 | /* |
335 | * Check whether the new device is a better fit than curdev. curdev | |
336 | * can be NULL ! | |
337 | */ | |
338 | bool tick_check_replacement(struct clock_event_device *curdev, | |
339 | struct clock_event_device *newdev) | |
340 | { | |
521c4299 | 341 | if (!tick_check_percpu(curdev, newdev, smp_processor_id())) |
03e13cf5 TG |
342 | return false; |
343 | ||
344 | return tick_check_preferred(curdev, newdev); | |
345 | } | |
346 | ||
906568c9 | 347 | /* |
7126cac4 TG |
348 | * Check, if the new registered device should be used. Called with |
349 | * clockevents_lock held and interrupts disabled. | |
906568c9 | 350 | */ |
7172a286 | 351 | void tick_check_new_device(struct clock_event_device *newdev) |
906568c9 TG |
352 | { |
353 | struct clock_event_device *curdev; | |
354 | struct tick_device *td; | |
7172a286 | 355 | int cpu; |
906568c9 TG |
356 | |
357 | cpu = smp_processor_id(); | |
906568c9 TG |
358 | td = &per_cpu(tick_cpu_device, cpu); |
359 | curdev = td->evtdev; | |
906568c9 | 360 | |
d7840aaa | 361 | if (!tick_check_replacement(curdev, newdev)) |
45cb8e01 | 362 | goto out_bc; |
906568c9 | 363 | |
ccf33d68 TG |
364 | if (!try_module_get(newdev->owner)) |
365 | return; | |
366 | ||
906568c9 TG |
367 | /* |
368 | * Replace the eventually existing device by the new | |
f8381cba TG |
369 | * device. If the current device is the broadcast device, do |
370 | * not give it back to the clockevents layer ! | |
906568c9 | 371 | */ |
f8381cba | 372 | if (tick_is_broadcast_device(curdev)) { |
2344abbc | 373 | clockevents_shutdown(curdev); |
f8381cba TG |
374 | curdev = NULL; |
375 | } | |
906568c9 | 376 | clockevents_exchange_device(curdev, newdev); |
6b954823 | 377 | tick_setup_device(td, newdev, cpu, cpumask_of(cpu)); |
79bf2bb3 TG |
378 | if (newdev->features & CLOCK_EVT_FEAT_ONESHOT) |
379 | tick_oneshot_notify(); | |
7172a286 | 380 | return; |
f8381cba TG |
381 | |
382 | out_bc: | |
383 | /* | |
384 | * Can the new device be used as a broadcast device ? | |
385 | */ | |
c94a8537 | 386 | tick_install_broadcast_device(newdev, cpu); |
906568c9 TG |
387 | } |
388 | ||
f32dd117 TG |
389 | /** |
390 | * tick_broadcast_oneshot_control - Enter/exit broadcast oneshot mode | |
391 | * @state: The target state (enter/exit) | |
392 | * | |
393 | * The system enters/leaves a state, where affected devices might stop | |
394 | * Returns 0 on success, -EBUSY if the cpu is used to broadcast wakeups. | |
395 | * | |
396 | * Called with interrupts disabled, so clockevents_lock is not | |
397 | * required here because the local clock event device cannot go away | |
398 | * under us. | |
399 | */ | |
400 | int tick_broadcast_oneshot_control(enum tick_broadcast_state state) | |
401 | { | |
402 | struct tick_device *td = this_cpu_ptr(&tick_cpu_device); | |
403 | ||
404 | if (!(td->evtdev->features & CLOCK_EVT_FEAT_C3STOP)) | |
405 | return 0; | |
406 | ||
407 | return __tick_broadcast_oneshot_control(state); | |
408 | } | |
0f447051 | 409 | EXPORT_SYMBOL_GPL(tick_broadcast_oneshot_control); |
f32dd117 | 410 | |
52c063d1 | 411 | #ifdef CONFIG_HOTPLUG_CPU |
94df7de0 SD |
412 | /* |
413 | * Transfer the do_timer job away from a dying cpu. | |
414 | * | |
f12ad423 | 415 | * Called with interrupts disabled. No locking required. If |
52c063d1 | 416 | * tick_do_timer_cpu is owned by this cpu, nothing can change it. |
94df7de0 | 417 | */ |
52c063d1 | 418 | void tick_handover_do_timer(void) |
94df7de0 | 419 | { |
f12ad423 TG |
420 | if (tick_do_timer_cpu == smp_processor_id()) |
421 | tick_do_timer_cpu = cpumask_first(cpu_online_mask); | |
94df7de0 SD |
422 | } |
423 | ||
906568c9 TG |
424 | /* |
425 | * Shutdown an event device on a given cpu: | |
426 | * | |
427 | * This is called on a life CPU, when a CPU is dead. So we cannot | |
428 | * access the hardware device itself. | |
429 | * We just set the mode and remove it from the lists. | |
430 | */ | |
a49b116d | 431 | void tick_shutdown(unsigned int cpu) |
906568c9 | 432 | { |
a49b116d | 433 | struct tick_device *td = &per_cpu(tick_cpu_device, cpu); |
906568c9 | 434 | struct clock_event_device *dev = td->evtdev; |
906568c9 | 435 | |
906568c9 TG |
436 | td->mode = TICKDEV_MODE_PERIODIC; |
437 | if (dev) { | |
438 | /* | |
439 | * Prevent that the clock events layer tries to call | |
440 | * the set mode function! | |
441 | */ | |
051ebd10 | 442 | clockevent_set_state(dev, CLOCK_EVT_STATE_DETACHED); |
906568c9 | 443 | clockevents_exchange_device(dev, NULL); |
6f7a05d7 | 444 | dev->event_handler = clockevents_handle_noop; |
906568c9 TG |
445 | td->evtdev = NULL; |
446 | } | |
906568c9 | 447 | } |
a49b116d | 448 | #endif |
906568c9 | 449 | |
4ffee521 | 450 | /** |
f46481d0 | 451 | * tick_suspend_local - Suspend the local tick device |
4ffee521 | 452 | * |
f46481d0 | 453 | * Called from the local cpu for freeze with interrupts disabled. |
4ffee521 TG |
454 | * |
455 | * No locks required. Nothing can change the per cpu device. | |
456 | */ | |
7270d11c | 457 | void tick_suspend_local(void) |
6321dd60 | 458 | { |
22127e93 | 459 | struct tick_device *td = this_cpu_ptr(&tick_cpu_device); |
6321dd60 | 460 | |
2344abbc | 461 | clockevents_shutdown(td->evtdev); |
6321dd60 TG |
462 | } |
463 | ||
4ffee521 | 464 | /** |
f46481d0 | 465 | * tick_resume_local - Resume the local tick device |
4ffee521 | 466 | * |
f46481d0 | 467 | * Called from the local CPU for unfreeze or XEN resume magic. |
4ffee521 TG |
468 | * |
469 | * No locks required. Nothing can change the per cpu device. | |
470 | */ | |
f46481d0 | 471 | void tick_resume_local(void) |
6321dd60 | 472 | { |
f46481d0 TG |
473 | struct tick_device *td = this_cpu_ptr(&tick_cpu_device); |
474 | bool broadcast = tick_resume_check_broadcast(); | |
6321dd60 | 475 | |
554ef387 | 476 | clockevents_tick_resume(td->evtdev); |
18de5bc4 TG |
477 | if (!broadcast) { |
478 | if (td->mode == TICKDEV_MODE_PERIODIC) | |
479 | tick_setup_periodic(td->evtdev, 0); | |
480 | else | |
481 | tick_resume_oneshot(); | |
482 | } | |
a761a67f TG |
483 | |
484 | /* | |
485 | * Ensure that hrtimers are up to date and the clockevents device | |
486 | * is reprogrammed correctly when high resolution timers are | |
487 | * enabled. | |
488 | */ | |
489 | hrtimers_resume_local(); | |
6321dd60 TG |
490 | } |
491 | ||
f46481d0 TG |
492 | /** |
493 | * tick_suspend - Suspend the tick and the broadcast device | |
494 | * | |
495 | * Called from syscore_suspend() via timekeeping_suspend with only one | |
496 | * CPU online and interrupts disabled or from tick_unfreeze() under | |
497 | * tick_freeze_lock. | |
498 | * | |
499 | * No locks required. Nothing can change the per cpu device. | |
500 | */ | |
501 | void tick_suspend(void) | |
502 | { | |
503 | tick_suspend_local(); | |
504 | tick_suspend_broadcast(); | |
505 | } | |
506 | ||
507 | /** | |
508 | * tick_resume - Resume the tick and the broadcast device | |
509 | * | |
510 | * Called from syscore_resume() via timekeeping_resume with only one | |
511 | * CPU online and interrupts disabled. | |
512 | * | |
513 | * No locks required. Nothing can change the per cpu device. | |
514 | */ | |
515 | void tick_resume(void) | |
516 | { | |
517 | tick_resume_broadcast(); | |
518 | tick_resume_local(); | |
519 | } | |
520 | ||
87e9b9f1 | 521 | #ifdef CONFIG_SUSPEND |
124cf911 RW |
522 | static DEFINE_RAW_SPINLOCK(tick_freeze_lock); |
523 | static unsigned int tick_freeze_depth; | |
524 | ||
525 | /** | |
526 | * tick_freeze - Suspend the local tick and (possibly) timekeeping. | |
527 | * | |
528 | * Check if this is the last online CPU executing the function and if so, | |
529 | * suspend timekeeping. Otherwise suspend the local tick. | |
530 | * | |
531 | * Call with interrupts disabled. Must be balanced with %tick_unfreeze(). | |
532 | * Interrupts must not be enabled before the subsequent %tick_unfreeze(). | |
533 | */ | |
534 | void tick_freeze(void) | |
535 | { | |
536 | raw_spin_lock(&tick_freeze_lock); | |
537 | ||
538 | tick_freeze_depth++; | |
75e0678e RW |
539 | if (tick_freeze_depth == num_online_cpus()) { |
540 | trace_suspend_resume(TPS("timekeeping_freeze"), | |
541 | smp_processor_id(), true); | |
c1a957d1 | 542 | system_state = SYSTEM_SUSPEND; |
3f2552f7 | 543 | sched_clock_suspend(); |
124cf911 | 544 | timekeeping_suspend(); |
75e0678e | 545 | } else { |
f46481d0 | 546 | tick_suspend_local(); |
75e0678e | 547 | } |
124cf911 RW |
548 | |
549 | raw_spin_unlock(&tick_freeze_lock); | |
550 | } | |
551 | ||
552 | /** | |
553 | * tick_unfreeze - Resume the local tick and (possibly) timekeeping. | |
554 | * | |
555 | * Check if this is the first CPU executing the function and if so, resume | |
556 | * timekeeping. Otherwise resume the local tick. | |
557 | * | |
558 | * Call with interrupts disabled. Must be balanced with %tick_freeze(). | |
559 | * Interrupts must not be enabled after the preceding %tick_freeze(). | |
560 | */ | |
561 | void tick_unfreeze(void) | |
562 | { | |
563 | raw_spin_lock(&tick_freeze_lock); | |
564 | ||
75e0678e | 565 | if (tick_freeze_depth == num_online_cpus()) { |
124cf911 | 566 | timekeeping_resume(); |
3f2552f7 | 567 | sched_clock_resume(); |
c1a957d1 | 568 | system_state = SYSTEM_RUNNING; |
75e0678e RW |
569 | trace_suspend_resume(TPS("timekeeping_freeze"), |
570 | smp_processor_id(), false); | |
571 | } else { | |
5167c506 | 572 | touch_softlockup_watchdog(); |
422fe750 | 573 | tick_resume_local(); |
75e0678e | 574 | } |
124cf911 RW |
575 | |
576 | tick_freeze_depth--; | |
577 | ||
578 | raw_spin_unlock(&tick_freeze_lock); | |
579 | } | |
87e9b9f1 | 580 | #endif /* CONFIG_SUSPEND */ |
124cf911 | 581 | |
906568c9 TG |
582 | /** |
583 | * tick_init - initialize the tick control | |
906568c9 TG |
584 | */ |
585 | void __init tick_init(void) | |
586 | { | |
b352bc1c | 587 | tick_broadcast_init(); |
a80e49e2 | 588 | tick_nohz_init(); |
906568c9 | 589 | } |