cpuidle.c revision a6220fc19afc07fe77cfd16f5b8e568615517091 
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
26DEFINE_PER_CPU(struct cpuidle_device *, cpuidle_devices);
27DEFINE_PER_CPU(struct cpuidle_device, cpuidle_dev);
28
29DEFINE_MUTEX(cpuidle_lock);
30LIST_HEAD(cpuidle_detected_devices);
31
32static int enabled_devices;
33static int off __read_mostly;
34static int initialized __read_mostly;
35static bool use_deepest_state __read_mostly;
36
37int cpuidle_disabled(void)
38{
39	return off;
40}
41void disable_cpuidle(void)
42{
43	off = 1;
44}
45
46/**
47 * cpuidle_play_dead - cpu off-lining
48 *
49 * Returns in case of an error or no driver
50 */
51int cpuidle_play_dead(void)
52{
53	struct cpuidle_device *dev = __this_cpu_read(cpuidle_devices);
54	struct cpuidle_driver *drv = cpuidle_get_cpu_driver(dev);
55	int i;
56
57	if (!drv)
58		return -ENODEV;
59
60	/* Find lowest-power state that supports long-term idle */
61	for (i = drv->state_count - 1; i >= CPUIDLE_DRIVER_STATE_START; i--)
62		if (drv->states[i].enter_dead)
63			return drv->states[i].enter_dead(dev, i);
64
65	return -ENODEV;
66}
67
68/**
69 * cpuidle_use_deepest_state - Enable/disable the "deepest idle" mode.
70 * @enable: Whether enable or disable the feature.
71 *
72 * If the "deepest idle" mode is enabled, cpuidle will ignore the governor and
73 * always use the state with the greatest exit latency (out of the states that
74 * are not disabled).
75 *
76 * This function can only be called after cpuidle_pause() to avoid races.
77 */
78void cpuidle_use_deepest_state(bool enable)
79{
80	use_deepest_state = enable;
81}
82
83/**
84 * cpuidle_find_deepest_state - Find the state of the greatest exit latency.
85 * @drv: cpuidle driver for a given CPU.
86 * @dev: cpuidle device for a given CPU.
87 */
88static int cpuidle_find_deepest_state(struct cpuidle_driver *drv,
89				      struct cpuidle_device *dev)
90{
91	unsigned int latency_req = 0;
92	int i, ret = CPUIDLE_DRIVER_STATE_START - 1;
93
94	for (i = CPUIDLE_DRIVER_STATE_START; i < drv->state_count; i++) {
95		struct cpuidle_state *s = &drv->states[i];
96		struct cpuidle_state_usage *su = &dev->states_usage[i];
97
98		if (s->disabled || su->disable || s->exit_latency <= latency_req)
99			continue;
100
101		latency_req = s->exit_latency;
102		ret = i;
103	}
104	return ret;
105}
106
107/**
108 * cpuidle_enter_state - enter the state and update stats
109 * @dev: cpuidle device for this cpu
110 * @drv: cpuidle driver for this cpu
111 * @next_state: index into drv->states of the state to enter
112 */
113int cpuidle_enter_state(struct cpuidle_device *dev, struct cpuidle_driver *drv,
114			int index)
115{
116	int entered_state;
117
118	struct cpuidle_state *target_state = &drv->states[index];
119	ktime_t time_start, time_end;
120	s64 diff;
121
122	time_start = ktime_get();
123
124	entered_state = target_state->enter(dev, drv, index);
125
126	time_end = ktime_get();
127
128	if (!cpuidle_state_is_coupled(dev, drv, entered_state))
129		local_irq_enable();
130
131	diff = ktime_to_us(ktime_sub(time_end, time_start));
132	if (diff > INT_MAX)
133		diff = INT_MAX;
134
135	dev->last_residency = (int) diff;
136
137	if (entered_state >= 0) {
138		/* Update cpuidle counters */
139		/* This can be moved to within driver enter routine
140		 * but that results in multiple copies of same code.
141		 */
142		dev->states_usage[entered_state].time += dev->last_residency;
143		dev->states_usage[entered_state].usage++;
144	} else {
145		dev->last_residency = 0;
146	}
147
148	return entered_state;
149}
150
151/**
152 * cpuidle_select - ask the cpuidle framework to choose an idle state
153 *
154 * @drv: the cpuidle driver
155 * @dev: the cpuidle device
156 *
157 * Returns the index of the idle state.
158 */
159int cpuidle_select(struct cpuidle_driver *drv, struct cpuidle_device *dev)
160{
161	if (off || !initialized)
162		return -ENODEV;
163
164	if (!drv || !dev || !dev->enabled)
165		return -EBUSY;
166
167	if (unlikely(use_deepest_state))
168		return cpuidle_find_deepest_state(drv, dev);
169
170	return cpuidle_curr_governor->select(drv, dev);
171}
172
173/**
174 * cpuidle_enter - enter into the specified idle state
175 *
176 * @drv:   the cpuidle driver tied with the cpu
177 * @dev:   the cpuidle device
178 * @index: the index in the idle state table
179 *
180 * Returns the index in the idle state, < 0 in case of error.
181 * The error code depends on the backend driver
182 */
183int cpuidle_enter(struct cpuidle_driver *drv, struct cpuidle_device *dev,
184		  int index)
185{
186	if (cpuidle_state_is_coupled(dev, drv, index))
187		return cpuidle_enter_state_coupled(dev, drv, index);
188	return cpuidle_enter_state(dev, drv, index);
189}
190
191/**
192 * cpuidle_reflect - tell the underlying governor what was the state
193 * we were in
194 *
195 * @dev  : the cpuidle device
196 * @index: the index in the idle state table
197 *
198 */
199void cpuidle_reflect(struct cpuidle_device *dev, int index)
200{
201	if (cpuidle_curr_governor->reflect && !unlikely(use_deepest_state))
202		cpuidle_curr_governor->reflect(dev, index);
203}
204
205/**
206 * cpuidle_install_idle_handler - installs the cpuidle idle loop handler
207 */
208void cpuidle_install_idle_handler(void)
209{
210	if (enabled_devices) {
211		/* Make sure all changes finished before we switch to new idle */
212		smp_wmb();
213		initialized = 1;
214	}
215}
216
217/**
218 * cpuidle_uninstall_idle_handler - uninstalls the cpuidle idle loop handler
219 */
220void cpuidle_uninstall_idle_handler(void)
221{
222	if (enabled_devices) {
223		initialized = 0;
224		kick_all_cpus_sync();
225	}
226}
227
228/**
229 * cpuidle_pause_and_lock - temporarily disables CPUIDLE
230 */
231void cpuidle_pause_and_lock(void)
232{
233	mutex_lock(&cpuidle_lock);
234	cpuidle_uninstall_idle_handler();
235}
236
237EXPORT_SYMBOL_GPL(cpuidle_pause_and_lock);
238
239/**
240 * cpuidle_resume_and_unlock - resumes CPUIDLE operation
241 */
242void cpuidle_resume_and_unlock(void)
243{
244	cpuidle_install_idle_handler();
245	mutex_unlock(&cpuidle_lock);
246}
247
248EXPORT_SYMBOL_GPL(cpuidle_resume_and_unlock);
249
250/* Currently used in suspend/resume path to suspend cpuidle */
251void cpuidle_pause(void)
252{
253	mutex_lock(&cpuidle_lock);
254	cpuidle_uninstall_idle_handler();
255	mutex_unlock(&cpuidle_lock);
256}
257
258/* Currently used in suspend/resume path to resume cpuidle */
259void cpuidle_resume(void)
260{
261	mutex_lock(&cpuidle_lock);
262	cpuidle_install_idle_handler();
263	mutex_unlock(&cpuidle_lock);
264}
265
266/**
267 * cpuidle_enable_device - enables idle PM for a CPU
268 * @dev: the CPU
269 *
270 * This function must be called between cpuidle_pause_and_lock and
271 * cpuidle_resume_and_unlock when used externally.
272 */
273int cpuidle_enable_device(struct cpuidle_device *dev)
274{
275	int ret;
276	struct cpuidle_driver *drv;
277
278	if (!dev)
279		return -EINVAL;
280
281	if (dev->enabled)
282		return 0;
283
284	drv = cpuidle_get_cpu_driver(dev);
285
286	if (!drv || !cpuidle_curr_governor)
287		return -EIO;
288
289	if (!dev->registered)
290		return -EINVAL;
291
292	if (!dev->state_count)
293		dev->state_count = drv->state_count;
294
295	ret = cpuidle_add_device_sysfs(dev);
296	if (ret)
297		return ret;
298
299	if (cpuidle_curr_governor->enable &&
300	    (ret = cpuidle_curr_governor->enable(drv, dev)))
301		goto fail_sysfs;
302
303	smp_wmb();
304
305	dev->enabled = 1;
306
307	enabled_devices++;
308	return 0;
309
310fail_sysfs:
311	cpuidle_remove_device_sysfs(dev);
312
313	return ret;
314}
315
316EXPORT_SYMBOL_GPL(cpuidle_enable_device);
317
318/**
319 * cpuidle_disable_device - disables idle PM for a CPU
320 * @dev: the CPU
321 *
322 * This function must be called between cpuidle_pause_and_lock and
323 * cpuidle_resume_and_unlock when used externally.
324 */
325void cpuidle_disable_device(struct cpuidle_device *dev)
326{
327	struct cpuidle_driver *drv = cpuidle_get_cpu_driver(dev);
328
329	if (!dev || !dev->enabled)
330		return;
331
332	if (!drv || !cpuidle_curr_governor)
333		return;
334
335	dev->enabled = 0;
336
337	if (cpuidle_curr_governor->disable)
338		cpuidle_curr_governor->disable(drv, dev);
339
340	cpuidle_remove_device_sysfs(dev);
341	enabled_devices--;
342}
343
344EXPORT_SYMBOL_GPL(cpuidle_disable_device);
345
346static void __cpuidle_unregister_device(struct cpuidle_device *dev)
347{
348	struct cpuidle_driver *drv = cpuidle_get_cpu_driver(dev);
349
350	list_del(&dev->device_list);
351	per_cpu(cpuidle_devices, dev->cpu) = NULL;
352	module_put(drv->owner);
353}
354
355static void __cpuidle_device_init(struct cpuidle_device *dev)
356{
357	memset(dev->states_usage, 0, sizeof(dev->states_usage));
358	dev->last_residency = 0;
359}
360
361/**
362 * __cpuidle_register_device - internal register function called before register
363 * and enable routines
364 * @dev: the cpu
365 *
366 * cpuidle_lock mutex must be held before this is called
367 */
368static int __cpuidle_register_device(struct cpuidle_device *dev)
369{
370	int ret;
371	struct cpuidle_driver *drv = cpuidle_get_cpu_driver(dev);
372
373	if (!try_module_get(drv->owner))
374		return -EINVAL;
375
376	per_cpu(cpuidle_devices, dev->cpu) = dev;
377	list_add(&dev->device_list, &cpuidle_detected_devices);
378
379	ret = cpuidle_coupled_register_device(dev);
380	if (ret)
381		__cpuidle_unregister_device(dev);
382	else
383		dev->registered = 1;
384
385	return ret;
386}
387
388/**
389 * cpuidle_register_device - registers a CPU's idle PM feature
390 * @dev: the cpu
391 */
392int cpuidle_register_device(struct cpuidle_device *dev)
393{
394	int ret = -EBUSY;
395
396	if (!dev)
397		return -EINVAL;
398
399	mutex_lock(&cpuidle_lock);
400
401	if (dev->registered)
402		goto out_unlock;
403
404	__cpuidle_device_init(dev);
405
406	ret = __cpuidle_register_device(dev);
407	if (ret)
408		goto out_unlock;
409
410	ret = cpuidle_add_sysfs(dev);
411	if (ret)
412		goto out_unregister;
413
414	ret = cpuidle_enable_device(dev);
415	if (ret)
416		goto out_sysfs;
417
418	cpuidle_install_idle_handler();
419
420out_unlock:
421	mutex_unlock(&cpuidle_lock);
422
423	return ret;
424
425out_sysfs:
426	cpuidle_remove_sysfs(dev);
427out_unregister:
428	__cpuidle_unregister_device(dev);
429	goto out_unlock;
430}
431
432EXPORT_SYMBOL_GPL(cpuidle_register_device);
433
434/**
435 * cpuidle_unregister_device - unregisters a CPU's idle PM feature
436 * @dev: the cpu
437 */
438void cpuidle_unregister_device(struct cpuidle_device *dev)
439{
440	if (!dev || dev->registered == 0)
441		return;
442
443	cpuidle_pause_and_lock();
444
445	cpuidle_disable_device(dev);
446
447	cpuidle_remove_sysfs(dev);
448
449	__cpuidle_unregister_device(dev);
450
451	cpuidle_coupled_unregister_device(dev);
452
453	cpuidle_resume_and_unlock();
454}
455
456EXPORT_SYMBOL_GPL(cpuidle_unregister_device);
457
458/**
459 * cpuidle_unregister: unregister a driver and the devices. This function
460 * can be used only if the driver has been previously registered through
461 * the cpuidle_register function.
462 *
463 * @drv: a valid pointer to a struct cpuidle_driver
464 */
465void cpuidle_unregister(struct cpuidle_driver *drv)
466{
467	int cpu;
468	struct cpuidle_device *device;
469
470	for_each_cpu(cpu, drv->cpumask) {
471		device = &per_cpu(cpuidle_dev, cpu);
472		cpuidle_unregister_device(device);
473	}
474
475	cpuidle_unregister_driver(drv);
476}
477EXPORT_SYMBOL_GPL(cpuidle_unregister);
478
479/**
480 * cpuidle_register: registers the driver and the cpu devices with the
481 * coupled_cpus passed as parameter. This function is used for all common
482 * initialization pattern there are in the arch specific drivers. The
483 * devices is globally defined in this file.
484 *
485 * @drv         : a valid pointer to a struct cpuidle_driver
486 * @coupled_cpus: a cpumask for the coupled states
487 *
488 * Returns 0 on success, < 0 otherwise
489 */
490int cpuidle_register(struct cpuidle_driver *drv,
491		     const struct cpumask *const coupled_cpus)
492{
493	int ret, cpu;
494	struct cpuidle_device *device;
495
496	ret = cpuidle_register_driver(drv);
497	if (ret) {
498		pr_err("failed to register cpuidle driver\n");
499		return ret;
500	}
501
502	for_each_cpu(cpu, drv->cpumask) {
503		device = &per_cpu(cpuidle_dev, cpu);
504		device->cpu = cpu;
505
506#ifdef CONFIG_ARCH_NEEDS_CPU_IDLE_COUPLED
507		/*
508		 * On multiplatform for ARM, the coupled idle states could be
509		 * enabled in the kernel even if the cpuidle driver does not
510		 * use it. Note, coupled_cpus is a struct copy.
511		 */
512		if (coupled_cpus)
513			device->coupled_cpus = *coupled_cpus;
514#endif
515		ret = cpuidle_register_device(device);
516		if (!ret)
517			continue;
518
519		pr_err("Failed to register cpuidle device for cpu%d\n", cpu);
520
521		cpuidle_unregister(drv);
522		break;
523	}
524
525	return ret;
526}
527EXPORT_SYMBOL_GPL(cpuidle_register);
528
529#ifdef CONFIG_SMP
530
531static void smp_callback(void *v)
532{
533	/* we already woke the CPU up, nothing more to do */
534}
535
536/*
537 * This function gets called when a part of the kernel has a new latency
538 * requirement.  This means we need to get all processors out of their C-state,
539 * and then recalculate a new suitable C-state. Just do a cross-cpu IPI; that
540 * wakes them all right up.
541 */
542static int cpuidle_latency_notify(struct notifier_block *b,
543		unsigned long l, void *v)
544{
545	smp_call_function(smp_callback, NULL, 1);
546	return NOTIFY_OK;
547}
548
549static struct notifier_block cpuidle_latency_notifier = {
550	.notifier_call = cpuidle_latency_notify,
551};
552
553static inline void latency_notifier_init(struct notifier_block *n)
554{
555	pm_qos_add_notifier(PM_QOS_CPU_DMA_LATENCY, n);
556}
557
558#else /* CONFIG_SMP */
559
560#define latency_notifier_init(x) do { } while (0)
561
562#endif /* CONFIG_SMP */
563
564/**
565 * cpuidle_init - core initializer
566 */
567static int __init cpuidle_init(void)
568{
569	int ret;
570
571	if (cpuidle_disabled())
572		return -ENODEV;
573
574	ret = cpuidle_add_interface(cpu_subsys.dev_root);
575	if (ret)
576		return ret;
577
578	latency_notifier_init(&cpuidle_latency_notifier);
579
580	return 0;
581}
582
583module_param(off, int, 0444);
584core_initcall(cpuidle_init);
585