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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/notifier.h> |
16 | #include <linux/pm_qos.h> |
17 | #include <linux/cpu.h> |
18 | #include <linux/cpuidle.h> |
19 | #include <linux/ktime.h> |
20 | #include <linux/hrtimer.h> |
21 | #include <linux/module.h> |
22 | #include <trace/events/power.h> |
23 | |
24 | #include "cpuidle.h" |
25 | |
26 | DEFINE_PER_CPU(struct cpuidle_device *, cpuidle_devices); |
27 | DEFINE_PER_CPU(struct cpuidle_device, cpuidle_dev); |
28 | |
29 | DEFINE_MUTEX(cpuidle_lock); |
30 | LIST_HEAD(cpuidle_detected_devices); |
31 | |
32 | static int enabled_devices; |
33 | static int off __read_mostly; |
34 | static int initialized __read_mostly; |
35 | |
36 | int cpuidle_disabled(void) |
37 | { |
38 | return off; |
39 | } |
40 | void disable_cpuidle(void) |
41 | { |
42 | off = 1; |
43 | } |
44 | |
45 | static int __cpuidle_register_device(struct cpuidle_device *dev); |
46 | |
47 | /** |
48 | * cpuidle_play_dead - cpu off-lining |
49 | * |
50 | * Returns in case of an error or no driver |
51 | */ |
52 | int cpuidle_play_dead(void) |
53 | { |
54 | struct cpuidle_device *dev = __this_cpu_read(cpuidle_devices); |
55 | struct cpuidle_driver *drv = cpuidle_get_cpu_driver(dev); |
56 | int i; |
57 | |
58 | if (!drv) |
59 | return -ENODEV; |
60 | |
61 | /* Find lowest-power state that supports long-term idle */ |
62 | for (i = drv->state_count - 1; i >= CPUIDLE_DRIVER_STATE_START; i--) |
63 | if (drv->states[i].enter_dead) |
64 | return drv->states[i].enter_dead(dev, i); |
65 | |
66 | return -ENODEV; |
67 | } |
68 | |
69 | /** |
70 | * cpuidle_enter_state - enter the state and update stats |
71 | * @dev: cpuidle device for this cpu |
72 | * @drv: cpuidle driver for this cpu |
73 | * @next_state: index into drv->states of the state to enter |
74 | */ |
75 | int cpuidle_enter_state(struct cpuidle_device *dev, struct cpuidle_driver *drv, |
76 | int index) |
77 | { |
78 | int entered_state; |
79 | |
80 | struct cpuidle_state *target_state = &drv->states[index]; |
81 | ktime_t time_start, time_end; |
82 | s64 diff; |
83 | |
84 | time_start = ktime_get(); |
85 | |
86 | entered_state = target_state->enter(dev, drv, index); |
87 | |
88 | time_end = ktime_get(); |
89 | |
90 | local_irq_enable(); |
91 | |
92 | diff = ktime_to_us(ktime_sub(time_end, time_start)); |
93 | if (diff > INT_MAX) |
94 | diff = INT_MAX; |
95 | |
96 | dev->last_residency = (int) diff; |
97 | |
98 | if (entered_state >= 0) { |
99 | /* Update cpuidle counters */ |
100 | /* This can be moved to within driver enter routine |
101 | * but that results in multiple copies of same code. |
102 | */ |
103 | dev->states_usage[entered_state].time += dev->last_residency; |
104 | dev->states_usage[entered_state].usage++; |
105 | } else { |
106 | dev->last_residency = 0; |
107 | } |
108 | |
109 | return entered_state; |
110 | } |
111 | |
112 | /** |
113 | * cpuidle_idle_call - the main idle loop |
114 | * |
115 | * NOTE: no locks or semaphores should be used here |
116 | * return non-zero on failure |
117 | */ |
118 | int cpuidle_idle_call(void) |
119 | { |
120 | struct cpuidle_device *dev = __this_cpu_read(cpuidle_devices); |
121 | struct cpuidle_driver *drv; |
122 | int next_state, entered_state; |
123 | |
124 | if (off) |
125 | return -ENODEV; |
126 | |
127 | if (!initialized) |
128 | return -ENODEV; |
129 | |
130 | /* check if the device is ready */ |
131 | if (!dev || !dev->enabled) |
132 | return -EBUSY; |
133 | |
134 | drv = cpuidle_get_cpu_driver(dev); |
135 | |
136 | /* ask the governor for the next state */ |
137 | next_state = cpuidle_curr_governor->select(drv, dev); |
138 | if (need_resched()) { |
139 | dev->last_residency = 0; |
140 | /* give the governor an opportunity to reflect on the outcome */ |
141 | if (cpuidle_curr_governor->reflect) |
142 | cpuidle_curr_governor->reflect(dev, next_state); |
143 | local_irq_enable(); |
144 | return 0; |
145 | } |
146 | |
147 | trace_cpu_idle_rcuidle(next_state, dev->cpu); |
148 | |
149 | if (drv->states[next_state].flags & CPUIDLE_FLAG_TIMER_STOP) |
150 | clockevents_notify(CLOCK_EVT_NOTIFY_BROADCAST_ENTER, |
151 | &dev->cpu); |
152 | |
153 | if (cpuidle_state_is_coupled(dev, drv, next_state)) |
154 | entered_state = cpuidle_enter_state_coupled(dev, drv, |
155 | next_state); |
156 | else |
157 | entered_state = cpuidle_enter_state(dev, drv, next_state); |
158 | |
159 | if (drv->states[next_state].flags & CPUIDLE_FLAG_TIMER_STOP) |
160 | clockevents_notify(CLOCK_EVT_NOTIFY_BROADCAST_EXIT, |
161 | &dev->cpu); |
162 | |
163 | trace_cpu_idle_rcuidle(PWR_EVENT_EXIT, dev->cpu); |
164 | |
165 | /* give the governor an opportunity to reflect on the outcome */ |
166 | if (cpuidle_curr_governor->reflect) |
167 | cpuidle_curr_governor->reflect(dev, entered_state); |
168 | |
169 | return 0; |
170 | } |
171 | |
172 | /** |
173 | * cpuidle_install_idle_handler - installs the cpuidle idle loop handler |
174 | */ |
175 | void cpuidle_install_idle_handler(void) |
176 | { |
177 | if (enabled_devices) { |
178 | /* Make sure all changes finished before we switch to new idle */ |
179 | smp_wmb(); |
180 | initialized = 1; |
181 | } |
182 | } |
183 | |
184 | /** |
185 | * cpuidle_uninstall_idle_handler - uninstalls the cpuidle idle loop handler |
186 | */ |
187 | void cpuidle_uninstall_idle_handler(void) |
188 | { |
189 | if (enabled_devices) { |
190 | initialized = 0; |
191 | kick_all_cpus_sync(); |
192 | } |
193 | } |
194 | |
195 | /** |
196 | * cpuidle_pause_and_lock - temporarily disables CPUIDLE |
197 | */ |
198 | void cpuidle_pause_and_lock(void) |
199 | { |
200 | mutex_lock(&cpuidle_lock); |
201 | cpuidle_uninstall_idle_handler(); |
202 | } |
203 | |
204 | EXPORT_SYMBOL_GPL(cpuidle_pause_and_lock); |
205 | |
206 | /** |
207 | * cpuidle_resume_and_unlock - resumes CPUIDLE operation |
208 | */ |
209 | void cpuidle_resume_and_unlock(void) |
210 | { |
211 | cpuidle_install_idle_handler(); |
212 | mutex_unlock(&cpuidle_lock); |
213 | } |
214 | |
215 | EXPORT_SYMBOL_GPL(cpuidle_resume_and_unlock); |
216 | |
217 | /* Currently used in suspend/resume path to suspend cpuidle */ |
218 | void cpuidle_pause(void) |
219 | { |
220 | mutex_lock(&cpuidle_lock); |
221 | cpuidle_uninstall_idle_handler(); |
222 | mutex_unlock(&cpuidle_lock); |
223 | } |
224 | |
225 | /* Currently used in suspend/resume path to resume cpuidle */ |
226 | void cpuidle_resume(void) |
227 | { |
228 | mutex_lock(&cpuidle_lock); |
229 | cpuidle_install_idle_handler(); |
230 | mutex_unlock(&cpuidle_lock); |
231 | } |
232 | |
233 | #ifdef CONFIG_ARCH_HAS_CPU_RELAX |
234 | static int poll_idle(struct cpuidle_device *dev, |
235 | struct cpuidle_driver *drv, int index) |
236 | { |
237 | ktime_t t1, t2; |
238 | s64 diff; |
239 | |
240 | t1 = ktime_get(); |
241 | local_irq_enable(); |
242 | while (!need_resched()) |
243 | cpu_relax(); |
244 | |
245 | t2 = ktime_get(); |
246 | diff = ktime_to_us(ktime_sub(t2, t1)); |
247 | if (diff > INT_MAX) |
248 | diff = INT_MAX; |
249 | |
250 | dev->last_residency = (int) diff; |
251 | |
252 | return index; |
253 | } |
254 | |
255 | static void poll_idle_init(struct cpuidle_driver *drv) |
256 | { |
257 | struct cpuidle_state *state = &drv->states[0]; |
258 | |
259 | snprintf(state->name, CPUIDLE_NAME_LEN, "POLL"); |
260 | snprintf(state->desc, CPUIDLE_DESC_LEN, "CPUIDLE CORE POLL IDLE"); |
261 | state->exit_latency = 0; |
262 | state->target_residency = 0; |
263 | state->power_usage = -1; |
264 | state->flags = 0; |
265 | state->enter = poll_idle; |
266 | state->disabled = false; |
267 | } |
268 | #else |
269 | static void poll_idle_init(struct cpuidle_driver *drv) {} |
270 | #endif /* CONFIG_ARCH_HAS_CPU_RELAX */ |
271 | |
272 | /** |
273 | * cpuidle_enable_device - enables idle PM for a CPU |
274 | * @dev: the CPU |
275 | * |
276 | * This function must be called between cpuidle_pause_and_lock and |
277 | * cpuidle_resume_and_unlock when used externally. |
278 | */ |
279 | int cpuidle_enable_device(struct cpuidle_device *dev) |
280 | { |
281 | int ret, i; |
282 | struct cpuidle_driver *drv; |
283 | |
284 | if (!dev) |
285 | return -EINVAL; |
286 | |
287 | if (dev->enabled) |
288 | return 0; |
289 | |
290 | drv = cpuidle_get_cpu_driver(dev); |
291 | |
292 | if (!drv || !cpuidle_curr_governor) |
293 | return -EIO; |
294 | |
295 | if (!dev->state_count) |
296 | dev->state_count = drv->state_count; |
297 | |
298 | if (dev->registered == 0) { |
299 | ret = __cpuidle_register_device(dev); |
300 | if (ret) |
301 | return ret; |
302 | } |
303 | |
304 | poll_idle_init(drv); |
305 | |
306 | ret = cpuidle_add_device_sysfs(dev); |
307 | if (ret) |
308 | return ret; |
309 | |
310 | if (cpuidle_curr_governor->enable && |
311 | (ret = cpuidle_curr_governor->enable(drv, dev))) |
312 | goto fail_sysfs; |
313 | |
314 | for (i = 0; i < dev->state_count; i++) { |
315 | dev->states_usage[i].usage = 0; |
316 | dev->states_usage[i].time = 0; |
317 | } |
318 | dev->last_residency = 0; |
319 | |
320 | smp_wmb(); |
321 | |
322 | dev->enabled = 1; |
323 | |
324 | enabled_devices++; |
325 | return 0; |
326 | |
327 | fail_sysfs: |
328 | cpuidle_remove_device_sysfs(dev); |
329 | |
330 | return ret; |
331 | } |
332 | |
333 | EXPORT_SYMBOL_GPL(cpuidle_enable_device); |
334 | |
335 | /** |
336 | * cpuidle_disable_device - disables idle PM for a CPU |
337 | * @dev: the CPU |
338 | * |
339 | * This function must be called between cpuidle_pause_and_lock and |
340 | * cpuidle_resume_and_unlock when used externally. |
341 | */ |
342 | void cpuidle_disable_device(struct cpuidle_device *dev) |
343 | { |
344 | struct cpuidle_driver *drv = cpuidle_get_cpu_driver(dev); |
345 | |
346 | if (!dev || !dev->enabled) |
347 | return; |
348 | |
349 | if (!drv || !cpuidle_curr_governor) |
350 | return; |
351 | |
352 | dev->enabled = 0; |
353 | |
354 | if (cpuidle_curr_governor->disable) |
355 | cpuidle_curr_governor->disable(drv, dev); |
356 | |
357 | cpuidle_remove_device_sysfs(dev); |
358 | enabled_devices--; |
359 | } |
360 | |
361 | EXPORT_SYMBOL_GPL(cpuidle_disable_device); |
362 | |
363 | /** |
364 | * __cpuidle_register_device - internal register function called before register |
365 | * and enable routines |
366 | * @dev: the cpu |
367 | * |
368 | * cpuidle_lock mutex must be held before this is called |
369 | */ |
370 | static int __cpuidle_register_device(struct cpuidle_device *dev) |
371 | { |
372 | int ret; |
373 | struct cpuidle_driver *drv = cpuidle_get_cpu_driver(dev); |
374 | |
375 | if (!try_module_get(drv->owner)) |
376 | return -EINVAL; |
377 | |
378 | per_cpu(cpuidle_devices, dev->cpu) = dev; |
379 | list_add(&dev->device_list, &cpuidle_detected_devices); |
380 | ret = cpuidle_add_sysfs(dev); |
381 | if (ret) |
382 | goto err_sysfs; |
383 | |
384 | ret = cpuidle_coupled_register_device(dev); |
385 | if (ret) |
386 | goto err_coupled; |
387 | |
388 | dev->registered = 1; |
389 | return 0; |
390 | |
391 | err_coupled: |
392 | cpuidle_remove_sysfs(dev); |
393 | err_sysfs: |
394 | list_del(&dev->device_list); |
395 | per_cpu(cpuidle_devices, dev->cpu) = NULL; |
396 | module_put(drv->owner); |
397 | return ret; |
398 | } |
399 | |
400 | /** |
401 | * cpuidle_register_device - registers a CPU's idle PM feature |
402 | * @dev: the cpu |
403 | */ |
404 | int cpuidle_register_device(struct cpuidle_device *dev) |
405 | { |
406 | int ret; |
407 | |
408 | if (!dev) |
409 | return -EINVAL; |
410 | |
411 | mutex_lock(&cpuidle_lock); |
412 | |
413 | if ((ret = __cpuidle_register_device(dev))) { |
414 | mutex_unlock(&cpuidle_lock); |
415 | return ret; |
416 | } |
417 | |
418 | cpuidle_enable_device(dev); |
419 | cpuidle_install_idle_handler(); |
420 | |
421 | mutex_unlock(&cpuidle_lock); |
422 | |
423 | return 0; |
424 | |
425 | } |
426 | |
427 | EXPORT_SYMBOL_GPL(cpuidle_register_device); |
428 | |
429 | /** |
430 | * cpuidle_unregister_device - unregisters a CPU's idle PM feature |
431 | * @dev: the cpu |
432 | */ |
433 | void cpuidle_unregister_device(struct cpuidle_device *dev) |
434 | { |
435 | struct cpuidle_driver *drv = cpuidle_get_cpu_driver(dev); |
436 | |
437 | if (dev->registered == 0) |
438 | return; |
439 | |
440 | cpuidle_pause_and_lock(); |
441 | |
442 | cpuidle_disable_device(dev); |
443 | |
444 | cpuidle_remove_sysfs(dev); |
445 | list_del(&dev->device_list); |
446 | per_cpu(cpuidle_devices, dev->cpu) = NULL; |
447 | |
448 | cpuidle_coupled_unregister_device(dev); |
449 | |
450 | cpuidle_resume_and_unlock(); |
451 | |
452 | module_put(drv->owner); |
453 | } |
454 | |
455 | EXPORT_SYMBOL_GPL(cpuidle_unregister_device); |
456 | |
457 | /** |
458 | * cpuidle_unregister: unregister a driver and the devices. This function |
459 | * can be used only if the driver has been previously registered through |
460 | * the cpuidle_register function. |
461 | * |
462 | * @drv: a valid pointer to a struct cpuidle_driver |
463 | */ |
464 | void cpuidle_unregister(struct cpuidle_driver *drv) |
465 | { |
466 | int cpu; |
467 | struct cpuidle_device *device; |
468 | |
469 | for_each_cpu(cpu, drv->cpumask) { |
470 | device = &per_cpu(cpuidle_dev, cpu); |
471 | cpuidle_unregister_device(device); |
472 | } |
473 | |
474 | cpuidle_unregister_driver(drv); |
475 | } |
476 | EXPORT_SYMBOL_GPL(cpuidle_unregister); |
477 | |
478 | /** |
479 | * cpuidle_register: registers the driver and the cpu devices with the |
480 | * coupled_cpus passed as parameter. This function is used for all common |
481 | * initialization pattern there are in the arch specific drivers. The |
482 | * devices is globally defined in this file. |
483 | * |
484 | * @drv : a valid pointer to a struct cpuidle_driver |
485 | * @coupled_cpus: a cpumask for the coupled states |
486 | * |
487 | * Returns 0 on success, < 0 otherwise |
488 | */ |
489 | int cpuidle_register(struct cpuidle_driver *drv, |
490 | const struct cpumask *const coupled_cpus) |
491 | { |
492 | int ret, cpu; |
493 | struct cpuidle_device *device; |
494 | |
495 | ret = cpuidle_register_driver(drv); |
496 | if (ret) { |
497 | pr_err("failed to register cpuidle driver\n"); |
498 | return ret; |
499 | } |
500 | |
501 | for_each_cpu(cpu, drv->cpumask) { |
502 | device = &per_cpu(cpuidle_dev, cpu); |
503 | device->cpu = cpu; |
504 | |
505 | #ifdef CONFIG_ARCH_NEEDS_CPU_IDLE_COUPLED |
506 | /* |
507 | * On multiplatform for ARM, the coupled idle states could |
508 | * enabled in the kernel even if the cpuidle driver does not |
509 | * use it. Note, coupled_cpus is a struct copy. |
510 | */ |
511 | if (coupled_cpus) |
512 | device->coupled_cpus = *coupled_cpus; |
513 | #endif |
514 | ret = cpuidle_register_device(device); |
515 | if (!ret) |
516 | continue; |
517 | |
518 | pr_err("Failed to register cpuidle device for cpu%d\n", cpu); |
519 | |
520 | cpuidle_unregister(drv); |
521 | break; |
522 | } |
523 | |
524 | return ret; |
525 | } |
526 | EXPORT_SYMBOL_GPL(cpuidle_register); |
527 | |
528 | #ifdef CONFIG_SMP |
529 | |
530 | static void smp_callback(void *v) |
531 | { |
532 | /* we already woke the CPU up, nothing more to do */ |
533 | } |
534 | |
535 | /* |
536 | * This function gets called when a part of the kernel has a new latency |
537 | * requirement. This means we need to get all processors out of their C-state, |
538 | * and then recalculate a new suitable C-state. Just do a cross-cpu IPI; that |
539 | * wakes them all right up. |
540 | */ |
541 | static int cpuidle_latency_notify(struct notifier_block *b, |
542 | unsigned long l, void *v) |
543 | { |
544 | smp_call_function(smp_callback, NULL, 1); |
545 | return NOTIFY_OK; |
546 | } |
547 | |
548 | static struct notifier_block cpuidle_latency_notifier = { |
549 | .notifier_call = cpuidle_latency_notify, |
550 | }; |
551 | |
552 | static inline void latency_notifier_init(struct notifier_block *n) |
553 | { |
554 | pm_qos_add_notifier(PM_QOS_CPU_DMA_LATENCY, n); |
555 | } |
556 | |
557 | #else /* CONFIG_SMP */ |
558 | |
559 | #define latency_notifier_init(x) do { } while (0) |
560 | |
561 | #endif /* CONFIG_SMP */ |
562 | |
563 | /** |
564 | * cpuidle_init - core initializer |
565 | */ |
566 | static int __init cpuidle_init(void) |
567 | { |
568 | int ret; |
569 | |
570 | if (cpuidle_disabled()) |
571 | return -ENODEV; |
572 | |
573 | ret = cpuidle_add_interface(cpu_subsys.dev_root); |
574 | if (ret) |
575 | return ret; |
576 | |
577 | latency_notifier_init(&cpuidle_latency_notifier); |
578 | |
579 | return 0; |
580 | } |
581 | |
582 | module_param(off, int, 0444); |
583 | core_initcall(cpuidle_init); |
584 |
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