2 * cpuidle.c - core cpuidle infrastructure
4 * (C) 2006-2007 Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>
5 * Shaohua Li <shaohua.li@intel.com>
6 * Adam Belay <abelay@novell.com>
8 * This code is licenced under the GPL.
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 <linux/suspend.h>
23 #include <linux/tick.h>
24 #include <trace/events/power.h>
28 DEFINE_PER_CPU(struct cpuidle_device *, cpuidle_devices);
29 DEFINE_PER_CPU(struct cpuidle_device, cpuidle_dev);
31 DEFINE_MUTEX(cpuidle_lock);
32 LIST_HEAD(cpuidle_detected_devices);
34 static int enabled_devices;
35 static int off __read_mostly;
36 static int initialized __read_mostly;
38 int cpuidle_disabled(void)
42 void disable_cpuidle(void)
47 bool cpuidle_not_available(struct cpuidle_driver *drv,
48 struct cpuidle_device *dev)
50 return off || !initialized || !drv || !dev || !dev->enabled;
54 * cpuidle_play_dead - cpu off-lining
56 * Returns in case of an error or no driver
58 int cpuidle_play_dead(void)
60 struct cpuidle_device *dev = __this_cpu_read(cpuidle_devices);
61 struct cpuidle_driver *drv = cpuidle_get_cpu_driver(dev);
67 /* Find lowest-power state that supports long-term idle */
68 for (i = drv->state_count - 1; i >= CPUIDLE_DRIVER_STATE_START; i--)
69 if (drv->states[i].enter_dead)
70 return drv->states[i].enter_dead(dev, i);
75 static int find_deepest_state(struct cpuidle_driver *drv,
76 struct cpuidle_device *dev, bool freeze)
78 unsigned int latency_req = 0;
79 int i, ret = freeze ? -1 : CPUIDLE_DRIVER_STATE_START - 1;
81 for (i = CPUIDLE_DRIVER_STATE_START; i < drv->state_count; i++) {
82 struct cpuidle_state *s = &drv->states[i];
83 struct cpuidle_state_usage *su = &dev->states_usage[i];
85 if (s->disabled || su->disable || s->exit_latency <= latency_req
86 || (freeze && !s->enter_freeze))
89 latency_req = s->exit_latency;
96 * cpuidle_find_deepest_state - Find the deepest available idle state.
97 * @drv: cpuidle driver for the given CPU.
98 * @dev: cpuidle device for the given CPU.
100 int cpuidle_find_deepest_state(struct cpuidle_driver *drv,
101 struct cpuidle_device *dev)
103 return find_deepest_state(drv, dev, false);
106 static void enter_freeze_proper(struct cpuidle_driver *drv,
107 struct cpuidle_device *dev, int index)
111 * The state used here cannot be a "coupled" one, because the "coupled"
112 * cpuidle mechanism enables interrupts and doing that with timekeeping
113 * suspended is generally unsafe.
115 drv->states[index].enter_freeze(dev, drv, index);
116 WARN_ON(!irqs_disabled());
118 * timekeeping_resume() that will be called by tick_unfreeze() for the
119 * last CPU executing it calls functions containing RCU read-side
120 * critical sections, so tell RCU about that.
122 RCU_NONIDLE(tick_unfreeze());
126 * cpuidle_enter_freeze - Enter an idle state suitable for suspend-to-idle.
127 * @drv: cpuidle driver for the given CPU.
128 * @dev: cpuidle device for the given CPU.
130 * If there are states with the ->enter_freeze callback, find the deepest of
131 * them and enter it with frozen tick.
133 int cpuidle_enter_freeze(struct cpuidle_driver *drv, struct cpuidle_device *dev)
138 * Find the deepest state with ->enter_freeze present, which guarantees
139 * that interrupts won't be enabled when it exits and allows the tick to
142 index = find_deepest_state(drv, dev, true);
144 enter_freeze_proper(drv, dev, index);
150 * cpuidle_enter_state - enter the state and update stats
151 * @dev: cpuidle device for this cpu
152 * @drv: cpuidle driver for this cpu
153 * @next_state: index into drv->states of the state to enter
155 int cpuidle_enter_state(struct cpuidle_device *dev, struct cpuidle_driver *drv,
160 struct cpuidle_state *target_state = &drv->states[index];
161 ktime_t time_start, time_end;
164 trace_cpu_idle_rcuidle(index, dev->cpu);
165 time_start = ktime_get();
167 entered_state = target_state->enter(dev, drv, index);
169 time_end = ktime_get();
170 trace_cpu_idle_rcuidle(PWR_EVENT_EXIT, dev->cpu);
172 if (!cpuidle_state_is_coupled(dev, drv, entered_state))
175 diff = ktime_to_us(ktime_sub(time_end, time_start));
179 dev->last_residency = (int) diff;
181 if (entered_state >= 0) {
182 /* Update cpuidle counters */
183 /* This can be moved to within driver enter routine
184 * but that results in multiple copies of same code.
186 dev->states_usage[entered_state].time += dev->last_residency;
187 dev->states_usage[entered_state].usage++;
189 dev->last_residency = 0;
192 return entered_state;
196 * cpuidle_select - ask the cpuidle framework to choose an idle state
198 * @drv: the cpuidle driver
199 * @dev: the cpuidle device
201 * Returns the index of the idle state.
203 int cpuidle_select(struct cpuidle_driver *drv, struct cpuidle_device *dev)
205 return cpuidle_curr_governor->select(drv, dev);
209 * cpuidle_enter - enter into the specified idle state
211 * @drv: the cpuidle driver tied with the cpu
212 * @dev: the cpuidle device
213 * @index: the index in the idle state table
215 * Returns the index in the idle state, < 0 in case of error.
216 * The error code depends on the backend driver
218 int cpuidle_enter(struct cpuidle_driver *drv, struct cpuidle_device *dev,
221 if (cpuidle_state_is_coupled(dev, drv, index))
222 return cpuidle_enter_state_coupled(dev, drv, index);
223 return cpuidle_enter_state(dev, drv, index);
227 * cpuidle_reflect - tell the underlying governor what was the state
230 * @dev : the cpuidle device
231 * @index: the index in the idle state table
234 void cpuidle_reflect(struct cpuidle_device *dev, int index)
236 if (cpuidle_curr_governor->reflect)
237 cpuidle_curr_governor->reflect(dev, index);
241 * cpuidle_install_idle_handler - installs the cpuidle idle loop handler
243 void cpuidle_install_idle_handler(void)
245 if (enabled_devices) {
246 /* Make sure all changes finished before we switch to new idle */
253 * cpuidle_uninstall_idle_handler - uninstalls the cpuidle idle loop handler
255 void cpuidle_uninstall_idle_handler(void)
257 if (enabled_devices) {
259 wake_up_all_idle_cpus();
263 * Make sure external observers (such as the scheduler)
264 * are done looking at pointed idle states.
270 * cpuidle_pause_and_lock - temporarily disables CPUIDLE
272 void cpuidle_pause_and_lock(void)
274 mutex_lock(&cpuidle_lock);
275 cpuidle_uninstall_idle_handler();
278 EXPORT_SYMBOL_GPL(cpuidle_pause_and_lock);
281 * cpuidle_resume_and_unlock - resumes CPUIDLE operation
283 void cpuidle_resume_and_unlock(void)
285 cpuidle_install_idle_handler();
286 mutex_unlock(&cpuidle_lock);
289 EXPORT_SYMBOL_GPL(cpuidle_resume_and_unlock);
291 /* Currently used in suspend/resume path to suspend cpuidle */
292 void cpuidle_pause(void)
294 mutex_lock(&cpuidle_lock);
295 cpuidle_uninstall_idle_handler();
296 mutex_unlock(&cpuidle_lock);
299 /* Currently used in suspend/resume path to resume cpuidle */
300 void cpuidle_resume(void)
302 mutex_lock(&cpuidle_lock);
303 cpuidle_install_idle_handler();
304 mutex_unlock(&cpuidle_lock);
308 * cpuidle_enable_device - enables idle PM for a CPU
311 * This function must be called between cpuidle_pause_and_lock and
312 * cpuidle_resume_and_unlock when used externally.
314 int cpuidle_enable_device(struct cpuidle_device *dev)
317 struct cpuidle_driver *drv;
325 drv = cpuidle_get_cpu_driver(dev);
327 if (!drv || !cpuidle_curr_governor)
330 if (!dev->registered)
333 ret = cpuidle_add_device_sysfs(dev);
337 if (cpuidle_curr_governor->enable &&
338 (ret = cpuidle_curr_governor->enable(drv, dev)))
349 cpuidle_remove_device_sysfs(dev);
354 EXPORT_SYMBOL_GPL(cpuidle_enable_device);
357 * cpuidle_disable_device - disables idle PM for a CPU
360 * This function must be called between cpuidle_pause_and_lock and
361 * cpuidle_resume_and_unlock when used externally.
363 void cpuidle_disable_device(struct cpuidle_device *dev)
365 struct cpuidle_driver *drv = cpuidle_get_cpu_driver(dev);
367 if (!dev || !dev->enabled)
370 if (!drv || !cpuidle_curr_governor)
375 if (cpuidle_curr_governor->disable)
376 cpuidle_curr_governor->disable(drv, dev);
378 cpuidle_remove_device_sysfs(dev);
382 EXPORT_SYMBOL_GPL(cpuidle_disable_device);
384 static void __cpuidle_unregister_device(struct cpuidle_device *dev)
386 struct cpuidle_driver *drv = cpuidle_get_cpu_driver(dev);
388 list_del(&dev->device_list);
389 per_cpu(cpuidle_devices, dev->cpu) = NULL;
390 module_put(drv->owner);
393 static void __cpuidle_device_init(struct cpuidle_device *dev)
395 memset(dev->states_usage, 0, sizeof(dev->states_usage));
396 dev->last_residency = 0;
400 * __cpuidle_register_device - internal register function called before register
401 * and enable routines
404 * cpuidle_lock mutex must be held before this is called
406 static int __cpuidle_register_device(struct cpuidle_device *dev)
409 struct cpuidle_driver *drv = cpuidle_get_cpu_driver(dev);
411 if (!try_module_get(drv->owner))
414 per_cpu(cpuidle_devices, dev->cpu) = dev;
415 list_add(&dev->device_list, &cpuidle_detected_devices);
417 ret = cpuidle_coupled_register_device(dev);
419 __cpuidle_unregister_device(dev);
427 * cpuidle_register_device - registers a CPU's idle PM feature
430 int cpuidle_register_device(struct cpuidle_device *dev)
437 mutex_lock(&cpuidle_lock);
442 __cpuidle_device_init(dev);
444 ret = __cpuidle_register_device(dev);
448 ret = cpuidle_add_sysfs(dev);
452 ret = cpuidle_enable_device(dev);
456 cpuidle_install_idle_handler();
459 mutex_unlock(&cpuidle_lock);
464 cpuidle_remove_sysfs(dev);
466 __cpuidle_unregister_device(dev);
470 EXPORT_SYMBOL_GPL(cpuidle_register_device);
473 * cpuidle_unregister_device - unregisters a CPU's idle PM feature
476 void cpuidle_unregister_device(struct cpuidle_device *dev)
478 if (!dev || dev->registered == 0)
481 cpuidle_pause_and_lock();
483 cpuidle_disable_device(dev);
485 cpuidle_remove_sysfs(dev);
487 __cpuidle_unregister_device(dev);
489 cpuidle_coupled_unregister_device(dev);
491 cpuidle_resume_and_unlock();
494 EXPORT_SYMBOL_GPL(cpuidle_unregister_device);
497 * cpuidle_unregister: unregister a driver and the devices. This function
498 * can be used only if the driver has been previously registered through
499 * the cpuidle_register function.
501 * @drv: a valid pointer to a struct cpuidle_driver
503 void cpuidle_unregister(struct cpuidle_driver *drv)
506 struct cpuidle_device *device;
508 for_each_cpu(cpu, drv->cpumask) {
509 device = &per_cpu(cpuidle_dev, cpu);
510 cpuidle_unregister_device(device);
513 cpuidle_unregister_driver(drv);
515 EXPORT_SYMBOL_GPL(cpuidle_unregister);
518 * cpuidle_register: registers the driver and the cpu devices with the
519 * coupled_cpus passed as parameter. This function is used for all common
520 * initialization pattern there are in the arch specific drivers. The
521 * devices is globally defined in this file.
523 * @drv : a valid pointer to a struct cpuidle_driver
524 * @coupled_cpus: a cpumask for the coupled states
526 * Returns 0 on success, < 0 otherwise
528 int cpuidle_register(struct cpuidle_driver *drv,
529 const struct cpumask *const coupled_cpus)
532 struct cpuidle_device *device;
534 ret = cpuidle_register_driver(drv);
536 pr_err("failed to register cpuidle driver\n");
540 for_each_cpu(cpu, drv->cpumask) {
541 device = &per_cpu(cpuidle_dev, cpu);
544 #ifdef CONFIG_ARCH_NEEDS_CPU_IDLE_COUPLED
546 * On multiplatform for ARM, the coupled idle states could be
547 * enabled in the kernel even if the cpuidle driver does not
548 * use it. Note, coupled_cpus is a struct copy.
551 device->coupled_cpus = *coupled_cpus;
553 ret = cpuidle_register_device(device);
557 pr_err("Failed to register cpuidle device for cpu%d\n", cpu);
559 cpuidle_unregister(drv);
565 EXPORT_SYMBOL_GPL(cpuidle_register);
570 * This function gets called when a part of the kernel has a new latency
571 * requirement. This means we need to get all processors out of their C-state,
572 * and then recalculate a new suitable C-state. Just do a cross-cpu IPI; that
573 * wakes them all right up.
575 static int cpuidle_latency_notify(struct notifier_block *b,
576 unsigned long l, void *v)
578 wake_up_all_idle_cpus();
582 static struct notifier_block cpuidle_latency_notifier = {
583 .notifier_call = cpuidle_latency_notify,
586 static inline void latency_notifier_init(struct notifier_block *n)
588 pm_qos_add_notifier(PM_QOS_CPU_DMA_LATENCY, n);
591 #else /* CONFIG_SMP */
593 #define latency_notifier_init(x) do { } while (0)
595 #endif /* CONFIG_SMP */
598 * cpuidle_init - core initializer
600 static int __init cpuidle_init(void)
604 if (cpuidle_disabled())
607 ret = cpuidle_add_interface(cpu_subsys.dev_root);
611 latency_notifier_init(&cpuidle_latency_notifier);
616 module_param(off, int, 0444);
617 core_initcall(cpuidle_init);