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1 | /* | |
2 | * cpuidle.c - core cpuidle infrastructure | |
3 | * | |
4 | * (C) 2006-2007 Venkatesh Pallipadi <venkatesh.pallipadi@intel.com> | |
5 | * Shaohua Li <shaohua.li@intel.com> | |
6 | * Adam Belay <abelay@novell.com> | |
7 | * | |
8 | * This code is licenced under the GPL. | |
9 | */ | |
10 | ||
11 | #include <linux/clockchips.h> | |
12 | #include <linux/kernel.h> | |
13 | #include <linux/mutex.h> | |
14 | #include <linux/sched.h> | |
15 | #include <linux/sched/clock.h> | |
16 | #include <linux/notifier.h> | |
17 | #include <linux/pm_qos.h> | |
18 | #include <linux/cpu.h> | |
19 | #include <linux/cpuidle.h> | |
20 | #include <linux/ktime.h> | |
21 | #include <linux/hrtimer.h> | |
22 | #include <linux/module.h> | |
23 | #include <linux/suspend.h> | |
24 | #include <linux/tick.h> | |
25 | #include <trace/events/power.h> | |
26 | ||
27 | #include "cpuidle.h" | |
28 | ||
29 | DEFINE_PER_CPU(struct cpuidle_device *, cpuidle_devices); | |
30 | DEFINE_PER_CPU(struct cpuidle_device, cpuidle_dev); | |
31 | ||
32 | DEFINE_MUTEX(cpuidle_lock); | |
33 | LIST_HEAD(cpuidle_detected_devices); | |
34 | ||
35 | static int enabled_devices; | |
36 | static int off __read_mostly; | |
37 | static int initialized __read_mostly; | |
38 | ||
39 | int cpuidle_disabled(void) | |
40 | { | |
41 | return off; | |
42 | } | |
43 | void disable_cpuidle(void) | |
44 | { | |
45 | off = 1; | |
46 | } | |
47 | ||
48 | bool cpuidle_not_available(struct cpuidle_driver *drv, | |
49 | struct cpuidle_device *dev) | |
50 | { | |
51 | return off || !initialized || !drv || !dev || !dev->enabled; | |
52 | } | |
53 | ||
54 | /** | |
55 | * cpuidle_play_dead - cpu off-lining | |
56 | * | |
57 | * Returns in case of an error or no driver | |
58 | */ | |
59 | int cpuidle_play_dead(void) | |
60 | { | |
61 | struct cpuidle_device *dev = __this_cpu_read(cpuidle_devices); | |
62 | struct cpuidle_driver *drv = cpuidle_get_cpu_driver(dev); | |
63 | int i; | |
64 | ||
65 | if (!drv) | |
66 | return -ENODEV; | |
67 | ||
68 | /* Find lowest-power state that supports long-term idle */ | |
69 | for (i = drv->state_count - 1; i >= 0; i--) | |
70 | if (drv->states[i].enter_dead) | |
71 | return drv->states[i].enter_dead(dev, i); | |
72 | ||
73 | return -ENODEV; | |
74 | } | |
75 | ||
76 | static int find_deepest_state(struct cpuidle_driver *drv, | |
77 | struct cpuidle_device *dev, | |
78 | unsigned int max_latency, | |
79 | unsigned int forbidden_flags, | |
80 | bool s2idle) | |
81 | { | |
82 | unsigned int latency_req = 0; | |
83 | int i, ret = 0; | |
84 | ||
85 | for (i = 1; i < drv->state_count; i++) { | |
86 | struct cpuidle_state *s = &drv->states[i]; | |
87 | struct cpuidle_state_usage *su = &dev->states_usage[i]; | |
88 | ||
89 | if (s->disabled || su->disable || s->exit_latency <= latency_req | |
90 | || s->exit_latency > max_latency | |
91 | || (s->flags & forbidden_flags) | |
92 | || (s2idle && !s->enter_s2idle)) | |
93 | continue; | |
94 | ||
95 | latency_req = s->exit_latency; | |
96 | ret = i; | |
97 | } | |
98 | return ret; | |
99 | } | |
100 | ||
101 | /** | |
102 | * cpuidle_use_deepest_state - Set/clear governor override flag. | |
103 | * @enable: New value of the flag. | |
104 | * | |
105 | * Set/unset the current CPU to use the deepest idle state (override governors | |
106 | * going forward if set). | |
107 | */ | |
108 | void cpuidle_use_deepest_state(bool enable) | |
109 | { | |
110 | struct cpuidle_device *dev; | |
111 | ||
112 | preempt_disable(); | |
113 | dev = cpuidle_get_device(); | |
114 | if (dev) | |
115 | dev->use_deepest_state = enable; | |
116 | preempt_enable(); | |
117 | } | |
118 | ||
119 | /** | |
120 | * cpuidle_find_deepest_state - Find the deepest available idle state. | |
121 | * @drv: cpuidle driver for the given CPU. | |
122 | * @dev: cpuidle device for the given CPU. | |
123 | */ | |
124 | int cpuidle_find_deepest_state(struct cpuidle_driver *drv, | |
125 | struct cpuidle_device *dev) | |
126 | { | |
127 | return find_deepest_state(drv, dev, UINT_MAX, 0, false); | |
128 | } | |
129 | ||
130 | #ifdef CONFIG_SUSPEND | |
131 | static void enter_s2idle_proper(struct cpuidle_driver *drv, | |
132 | struct cpuidle_device *dev, int index) | |
133 | { | |
134 | /* | |
135 | * trace_suspend_resume() called by tick_freeze() for the last CPU | |
136 | * executing it contains RCU usage regarded as invalid in the idle | |
137 | * context, so tell RCU about that. | |
138 | */ | |
139 | RCU_NONIDLE(tick_freeze()); | |
140 | /* | |
141 | * The state used here cannot be a "coupled" one, because the "coupled" | |
142 | * cpuidle mechanism enables interrupts and doing that with timekeeping | |
143 | * suspended is generally unsafe. | |
144 | */ | |
145 | stop_critical_timings(); | |
146 | drv->states[index].enter_s2idle(dev, drv, index); | |
147 | WARN_ON(!irqs_disabled()); | |
148 | /* | |
149 | * timekeeping_resume() that will be called by tick_unfreeze() for the | |
150 | * first CPU executing it calls functions containing RCU read-side | |
151 | * critical sections, so tell RCU about that. | |
152 | */ | |
153 | RCU_NONIDLE(tick_unfreeze()); | |
154 | start_critical_timings(); | |
155 | } | |
156 | ||
157 | /** | |
158 | * cpuidle_enter_s2idle - Enter an idle state suitable for suspend-to-idle. | |
159 | * @drv: cpuidle driver for the given CPU. | |
160 | * @dev: cpuidle device for the given CPU. | |
161 | * | |
162 | * If there are states with the ->enter_s2idle callback, find the deepest of | |
163 | * them and enter it with frozen tick. | |
164 | */ | |
165 | int cpuidle_enter_s2idle(struct cpuidle_driver *drv, struct cpuidle_device *dev) | |
166 | { | |
167 | int index; | |
168 | ||
169 | /* | |
170 | * Find the deepest state with ->enter_s2idle present, which guarantees | |
171 | * that interrupts won't be enabled when it exits and allows the tick to | |
172 | * be frozen safely. | |
173 | */ | |
174 | index = find_deepest_state(drv, dev, UINT_MAX, 0, true); | |
175 | if (index > 0) | |
176 | enter_s2idle_proper(drv, dev, index); | |
177 | ||
178 | return index; | |
179 | } | |
180 | #endif /* CONFIG_SUSPEND */ | |
181 | ||
182 | /** | |
183 | * cpuidle_enter_state - enter the state and update stats | |
184 | * @dev: cpuidle device for this cpu | |
185 | * @drv: cpuidle driver for this cpu | |
186 | * @index: index into the states table in @drv of the state to enter | |
187 | */ | |
188 | int cpuidle_enter_state(struct cpuidle_device *dev, struct cpuidle_driver *drv, | |
189 | int index) | |
190 | { | |
191 | int entered_state; | |
192 | ||
193 | struct cpuidle_state *target_state = &drv->states[index]; | |
194 | bool broadcast = !!(target_state->flags & CPUIDLE_FLAG_TIMER_STOP); | |
195 | ktime_t time_start, time_end; | |
196 | s64 diff; | |
197 | ||
198 | /* | |
199 | * Tell the time framework to switch to a broadcast timer because our | |
200 | * local timer will be shut down. If a local timer is used from another | |
201 | * CPU as a broadcast timer, this call may fail if it is not available. | |
202 | */ | |
203 | if (broadcast && tick_broadcast_enter()) { | |
204 | index = find_deepest_state(drv, dev, target_state->exit_latency, | |
205 | CPUIDLE_FLAG_TIMER_STOP, false); | |
206 | if (index < 0) { | |
207 | default_idle_call(); | |
208 | return -EBUSY; | |
209 | } | |
210 | target_state = &drv->states[index]; | |
211 | broadcast = false; | |
212 | } | |
213 | ||
214 | /* Take note of the planned idle state. */ | |
215 | sched_idle_set_state(target_state); | |
216 | ||
217 | trace_cpu_idle_rcuidle(index, dev->cpu); | |
218 | time_start = ns_to_ktime(local_clock()); | |
219 | ||
220 | stop_critical_timings(); | |
221 | entered_state = target_state->enter(dev, drv, index); | |
222 | start_critical_timings(); | |
223 | ||
224 | sched_clock_idle_wakeup_event(); | |
225 | time_end = ns_to_ktime(local_clock()); | |
226 | trace_cpu_idle_rcuidle(PWR_EVENT_EXIT, dev->cpu); | |
227 | ||
228 | /* The cpu is no longer idle or about to enter idle. */ | |
229 | sched_idle_set_state(NULL); | |
230 | ||
231 | if (broadcast) { | |
232 | if (WARN_ON_ONCE(!irqs_disabled())) | |
233 | local_irq_disable(); | |
234 | ||
235 | tick_broadcast_exit(); | |
236 | } | |
237 | ||
238 | if (!cpuidle_state_is_coupled(drv, index)) | |
239 | local_irq_enable(); | |
240 | ||
241 | diff = ktime_us_delta(time_end, time_start); | |
242 | if (diff > INT_MAX) | |
243 | diff = INT_MAX; | |
244 | ||
245 | dev->last_residency = (int) diff; | |
246 | ||
247 | if (entered_state >= 0) { | |
248 | /* Update cpuidle counters */ | |
249 | /* This can be moved to within driver enter routine | |
250 | * but that results in multiple copies of same code. | |
251 | */ | |
252 | dev->states_usage[entered_state].time += dev->last_residency; | |
253 | dev->states_usage[entered_state].usage++; | |
254 | } else { | |
255 | dev->last_residency = 0; | |
256 | } | |
257 | ||
258 | return entered_state; | |
259 | } | |
260 | ||
261 | /** | |
262 | * cpuidle_select - ask the cpuidle framework to choose an idle state | |
263 | * | |
264 | * @drv: the cpuidle driver | |
265 | * @dev: the cpuidle device | |
266 | * | |
267 | * Returns the index of the idle state. The return value must not be negative. | |
268 | */ | |
269 | int cpuidle_select(struct cpuidle_driver *drv, struct cpuidle_device *dev) | |
270 | { | |
271 | return cpuidle_curr_governor->select(drv, dev); | |
272 | } | |
273 | ||
274 | /** | |
275 | * cpuidle_enter - enter into the specified idle state | |
276 | * | |
277 | * @drv: the cpuidle driver tied with the cpu | |
278 | * @dev: the cpuidle device | |
279 | * @index: the index in the idle state table | |
280 | * | |
281 | * Returns the index in the idle state, < 0 in case of error. | |
282 | * The error code depends on the backend driver | |
283 | */ | |
284 | int cpuidle_enter(struct cpuidle_driver *drv, struct cpuidle_device *dev, | |
285 | int index) | |
286 | { | |
287 | if (cpuidle_state_is_coupled(drv, index)) | |
288 | return cpuidle_enter_state_coupled(dev, drv, index); | |
289 | return cpuidle_enter_state(dev, drv, index); | |
290 | } | |
291 | ||
292 | /** | |
293 | * cpuidle_reflect - tell the underlying governor what was the state | |
294 | * we were in | |
295 | * | |
296 | * @dev : the cpuidle device | |
297 | * @index: the index in the idle state table | |
298 | * | |
299 | */ | |
300 | void cpuidle_reflect(struct cpuidle_device *dev, int index) | |
301 | { | |
302 | if (cpuidle_curr_governor->reflect && index >= 0) | |
303 | cpuidle_curr_governor->reflect(dev, index); | |
304 | } | |
305 | ||
306 | /** | |
307 | * cpuidle_install_idle_handler - installs the cpuidle idle loop handler | |
308 | */ | |
309 | void cpuidle_install_idle_handler(void) | |
310 | { | |
311 | if (enabled_devices) { | |
312 | /* Make sure all changes finished before we switch to new idle */ | |
313 | smp_wmb(); | |
314 | initialized = 1; | |
315 | } | |
316 | } | |
317 | ||
318 | /** | |
319 | * cpuidle_uninstall_idle_handler - uninstalls the cpuidle idle loop handler | |
320 | */ | |
321 | void cpuidle_uninstall_idle_handler(void) | |
322 | { | |
323 | if (enabled_devices) { | |
324 | initialized = 0; | |
325 | wake_up_all_idle_cpus(); | |
326 | } | |
327 | ||
328 | /* | |
329 | * Make sure external observers (such as the scheduler) | |
330 | * are done looking at pointed idle states. | |
331 | */ | |
332 | synchronize_rcu(); | |
333 | } | |
334 | ||
335 | /** | |
336 | * cpuidle_pause_and_lock - temporarily disables CPUIDLE | |
337 | */ | |
338 | void cpuidle_pause_and_lock(void) | |
339 | { | |
340 | mutex_lock(&cpuidle_lock); | |
341 | cpuidle_uninstall_idle_handler(); | |
342 | } | |
343 | ||
344 | EXPORT_SYMBOL_GPL(cpuidle_pause_and_lock); | |
345 | ||
346 | /** | |
347 | * cpuidle_resume_and_unlock - resumes CPUIDLE operation | |
348 | */ | |
349 | void cpuidle_resume_and_unlock(void) | |
350 | { | |
351 | cpuidle_install_idle_handler(); | |
352 | mutex_unlock(&cpuidle_lock); | |
353 | } | |
354 | ||
355 | EXPORT_SYMBOL_GPL(cpuidle_resume_and_unlock); | |
356 | ||
357 | /* Currently used in suspend/resume path to suspend cpuidle */ | |
358 | void cpuidle_pause(void) | |
359 | { | |
360 | mutex_lock(&cpuidle_lock); | |
361 | cpuidle_uninstall_idle_handler(); | |
362 | mutex_unlock(&cpuidle_lock); | |
363 | } | |
364 | ||
365 | /* Currently used in suspend/resume path to resume cpuidle */ | |
366 | void cpuidle_resume(void) | |
367 | { | |
368 | mutex_lock(&cpuidle_lock); | |
369 | cpuidle_install_idle_handler(); | |
370 | mutex_unlock(&cpuidle_lock); | |
371 | } | |
372 | ||
373 | /** | |
374 | * cpuidle_enable_device - enables idle PM for a CPU | |
375 | * @dev: the CPU | |
376 | * | |
377 | * This function must be called between cpuidle_pause_and_lock and | |
378 | * cpuidle_resume_and_unlock when used externally. | |
379 | */ | |
380 | int cpuidle_enable_device(struct cpuidle_device *dev) | |
381 | { | |
382 | int ret; | |
383 | struct cpuidle_driver *drv; | |
384 | ||
385 | if (!dev) | |
386 | return -EINVAL; | |
387 | ||
388 | if (dev->enabled) | |
389 | return 0; | |
390 | ||
391 | if (!cpuidle_curr_governor) | |
392 | return -EIO; | |
393 | ||
394 | drv = cpuidle_get_cpu_driver(dev); | |
395 | ||
396 | if (!drv) | |
397 | return -EIO; | |
398 | ||
399 | if (!dev->registered) | |
400 | return -EINVAL; | |
401 | ||
402 | ret = cpuidle_add_device_sysfs(dev); | |
403 | if (ret) | |
404 | return ret; | |
405 | ||
406 | if (cpuidle_curr_governor->enable) { | |
407 | ret = cpuidle_curr_governor->enable(drv, dev); | |
408 | if (ret) | |
409 | goto fail_sysfs; | |
410 | } | |
411 | ||
412 | smp_wmb(); | |
413 | ||
414 | dev->enabled = 1; | |
415 | ||
416 | enabled_devices++; | |
417 | return 0; | |
418 | ||
419 | fail_sysfs: | |
420 | cpuidle_remove_device_sysfs(dev); | |
421 | ||
422 | return ret; | |
423 | } | |
424 | ||
425 | EXPORT_SYMBOL_GPL(cpuidle_enable_device); | |
426 | ||
427 | /** | |
428 | * cpuidle_disable_device - disables idle PM for a CPU | |
429 | * @dev: the CPU | |
430 | * | |
431 | * This function must be called between cpuidle_pause_and_lock and | |
432 | * cpuidle_resume_and_unlock when used externally. | |
433 | */ | |
434 | void cpuidle_disable_device(struct cpuidle_device *dev) | |
435 | { | |
436 | struct cpuidle_driver *drv = cpuidle_get_cpu_driver(dev); | |
437 | ||
438 | if (!dev || !dev->enabled) | |
439 | return; | |
440 | ||
441 | if (!drv || !cpuidle_curr_governor) | |
442 | return; | |
443 | ||
444 | dev->enabled = 0; | |
445 | ||
446 | if (cpuidle_curr_governor->disable) | |
447 | cpuidle_curr_governor->disable(drv, dev); | |
448 | ||
449 | cpuidle_remove_device_sysfs(dev); | |
450 | enabled_devices--; | |
451 | } | |
452 | ||
453 | EXPORT_SYMBOL_GPL(cpuidle_disable_device); | |
454 | ||
455 | static void __cpuidle_unregister_device(struct cpuidle_device *dev) | |
456 | { | |
457 | struct cpuidle_driver *drv = cpuidle_get_cpu_driver(dev); | |
458 | ||
459 | list_del(&dev->device_list); | |
460 | per_cpu(cpuidle_devices, dev->cpu) = NULL; | |
461 | module_put(drv->owner); | |
462 | ||
463 | dev->registered = 0; | |
464 | } | |
465 | ||
466 | static void __cpuidle_device_init(struct cpuidle_device *dev) | |
467 | { | |
468 | memset(dev->states_usage, 0, sizeof(dev->states_usage)); | |
469 | dev->last_residency = 0; | |
470 | } | |
471 | ||
472 | /** | |
473 | * __cpuidle_register_device - internal register function called before register | |
474 | * and enable routines | |
475 | * @dev: the cpu | |
476 | * | |
477 | * cpuidle_lock mutex must be held before this is called | |
478 | */ | |
479 | static int __cpuidle_register_device(struct cpuidle_device *dev) | |
480 | { | |
481 | int ret; | |
482 | struct cpuidle_driver *drv = cpuidle_get_cpu_driver(dev); | |
483 | ||
484 | if (!try_module_get(drv->owner)) | |
485 | return -EINVAL; | |
486 | ||
487 | per_cpu(cpuidle_devices, dev->cpu) = dev; | |
488 | list_add(&dev->device_list, &cpuidle_detected_devices); | |
489 | ||
490 | ret = cpuidle_coupled_register_device(dev); | |
491 | if (ret) | |
492 | __cpuidle_unregister_device(dev); | |
493 | else | |
494 | dev->registered = 1; | |
495 | ||
496 | return ret; | |
497 | } | |
498 | ||
499 | /** | |
500 | * cpuidle_register_device - registers a CPU's idle PM feature | |
501 | * @dev: the cpu | |
502 | */ | |
503 | int cpuidle_register_device(struct cpuidle_device *dev) | |
504 | { | |
505 | int ret = -EBUSY; | |
506 | ||
507 | if (!dev) | |
508 | return -EINVAL; | |
509 | ||
510 | mutex_lock(&cpuidle_lock); | |
511 | ||
512 | if (dev->registered) | |
513 | goto out_unlock; | |
514 | ||
515 | __cpuidle_device_init(dev); | |
516 | ||
517 | ret = __cpuidle_register_device(dev); | |
518 | if (ret) | |
519 | goto out_unlock; | |
520 | ||
521 | ret = cpuidle_add_sysfs(dev); | |
522 | if (ret) | |
523 | goto out_unregister; | |
524 | ||
525 | ret = cpuidle_enable_device(dev); | |
526 | if (ret) | |
527 | goto out_sysfs; | |
528 | ||
529 | cpuidle_install_idle_handler(); | |
530 | ||
531 | out_unlock: | |
532 | mutex_unlock(&cpuidle_lock); | |
533 | ||
534 | return ret; | |
535 | ||
536 | out_sysfs: | |
537 | cpuidle_remove_sysfs(dev); | |
538 | out_unregister: | |
539 | __cpuidle_unregister_device(dev); | |
540 | goto out_unlock; | |
541 | } | |
542 | ||
543 | EXPORT_SYMBOL_GPL(cpuidle_register_device); | |
544 | ||
545 | /** | |
546 | * cpuidle_unregister_device - unregisters a CPU's idle PM feature | |
547 | * @dev: the cpu | |
548 | */ | |
549 | void cpuidle_unregister_device(struct cpuidle_device *dev) | |
550 | { | |
551 | if (!dev || dev->registered == 0) | |
552 | return; | |
553 | ||
554 | cpuidle_pause_and_lock(); | |
555 | ||
556 | cpuidle_disable_device(dev); | |
557 | ||
558 | cpuidle_remove_sysfs(dev); | |
559 | ||
560 | __cpuidle_unregister_device(dev); | |
561 | ||
562 | cpuidle_coupled_unregister_device(dev); | |
563 | ||
564 | cpuidle_resume_and_unlock(); | |
565 | } | |
566 | ||
567 | EXPORT_SYMBOL_GPL(cpuidle_unregister_device); | |
568 | ||
569 | /** | |
570 | * cpuidle_unregister: unregister a driver and the devices. This function | |
571 | * can be used only if the driver has been previously registered through | |
572 | * the cpuidle_register function. | |
573 | * | |
574 | * @drv: a valid pointer to a struct cpuidle_driver | |
575 | */ | |
576 | void cpuidle_unregister(struct cpuidle_driver *drv) | |
577 | { | |
578 | int cpu; | |
579 | struct cpuidle_device *device; | |
580 | ||
581 | for_each_cpu(cpu, drv->cpumask) { | |
582 | device = &per_cpu(cpuidle_dev, cpu); | |
583 | cpuidle_unregister_device(device); | |
584 | } | |
585 | ||
586 | cpuidle_unregister_driver(drv); | |
587 | } | |
588 | EXPORT_SYMBOL_GPL(cpuidle_unregister); | |
589 | ||
590 | /** | |
591 | * cpuidle_register: registers the driver and the cpu devices with the | |
592 | * coupled_cpus passed as parameter. This function is used for all common | |
593 | * initialization pattern there are in the arch specific drivers. The | |
594 | * devices is globally defined in this file. | |
595 | * | |
596 | * @drv : a valid pointer to a struct cpuidle_driver | |
597 | * @coupled_cpus: a cpumask for the coupled states | |
598 | * | |
599 | * Returns 0 on success, < 0 otherwise | |
600 | */ | |
601 | int cpuidle_register(struct cpuidle_driver *drv, | |
602 | const struct cpumask *const coupled_cpus) | |
603 | { | |
604 | int ret, cpu; | |
605 | struct cpuidle_device *device; | |
606 | ||
607 | ret = cpuidle_register_driver(drv); | |
608 | if (ret) { | |
609 | pr_err("failed to register cpuidle driver\n"); | |
610 | return ret; | |
611 | } | |
612 | ||
613 | for_each_cpu(cpu, drv->cpumask) { | |
614 | device = &per_cpu(cpuidle_dev, cpu); | |
615 | device->cpu = cpu; | |
616 | ||
617 | #ifdef CONFIG_ARCH_NEEDS_CPU_IDLE_COUPLED | |
618 | /* | |
619 | * On multiplatform for ARM, the coupled idle states could be | |
620 | * enabled in the kernel even if the cpuidle driver does not | |
621 | * use it. Note, coupled_cpus is a struct copy. | |
622 | */ | |
623 | if (coupled_cpus) | |
624 | device->coupled_cpus = *coupled_cpus; | |
625 | #endif | |
626 | ret = cpuidle_register_device(device); | |
627 | if (!ret) | |
628 | continue; | |
629 | ||
630 | pr_err("Failed to register cpuidle device for cpu%d\n", cpu); | |
631 | ||
632 | cpuidle_unregister(drv); | |
633 | break; | |
634 | } | |
635 | ||
636 | return ret; | |
637 | } | |
638 | EXPORT_SYMBOL_GPL(cpuidle_register); | |
639 | ||
640 | #ifdef CONFIG_SMP | |
641 | ||
642 | /* | |
643 | * This function gets called when a part of the kernel has a new latency | |
644 | * requirement. This means we need to get all processors out of their C-state, | |
645 | * and then recalculate a new suitable C-state. Just do a cross-cpu IPI; that | |
646 | * wakes them all right up. | |
647 | */ | |
648 | static int cpuidle_latency_notify(struct notifier_block *b, | |
649 | unsigned long l, void *v) | |
650 | { | |
651 | wake_up_all_idle_cpus(); | |
652 | return NOTIFY_OK; | |
653 | } | |
654 | ||
655 | static struct notifier_block cpuidle_latency_notifier = { | |
656 | .notifier_call = cpuidle_latency_notify, | |
657 | }; | |
658 | ||
659 | static inline void latency_notifier_init(struct notifier_block *n) | |
660 | { | |
661 | pm_qos_add_notifier(PM_QOS_CPU_DMA_LATENCY, n); | |
662 | } | |
663 | ||
664 | #else /* CONFIG_SMP */ | |
665 | ||
666 | #define latency_notifier_init(x) do { } while (0) | |
667 | ||
668 | #endif /* CONFIG_SMP */ | |
669 | ||
670 | /** | |
671 | * cpuidle_init - core initializer | |
672 | */ | |
673 | static int __init cpuidle_init(void) | |
674 | { | |
675 | int ret; | |
676 | ||
677 | if (cpuidle_disabled()) | |
678 | return -ENODEV; | |
679 | ||
680 | ret = cpuidle_add_interface(cpu_subsys.dev_root); | |
681 | if (ret) | |
682 | return ret; | |
683 | ||
684 | latency_notifier_init(&cpuidle_latency_notifier); | |
685 | ||
686 | return 0; | |
687 | } | |
688 | ||
689 | module_param(off, int, 0444); | |
690 | core_initcall(cpuidle_init); |