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 <trace/events/power.h>
26 DEFINE_PER_CPU(struct cpuidle_device *, cpuidle_devices);
27 DEFINE_PER_CPU(struct cpuidle_device, cpuidle_dev);
29 DEFINE_MUTEX(cpuidle_lock);
30 LIST_HEAD(cpuidle_detected_devices);
32 static int enabled_devices;
33 static int off __read_mostly;
34 static int initialized __read_mostly;
36 int cpuidle_disabled(void)
40 void disable_cpuidle(void)
46 * cpuidle_play_dead - cpu off-lining
48 * Returns in case of an error or no driver
50 int cpuidle_play_dead(void)
52 struct cpuidle_device *dev = __this_cpu_read(cpuidle_devices);
53 struct cpuidle_driver *drv = cpuidle_get_cpu_driver(dev);
59 /* Find lowest-power state that supports long-term idle */
60 for (i = drv->state_count - 1; i >= CPUIDLE_DRIVER_STATE_START; i--)
61 if (drv->states[i].enter_dead)
62 return drv->states[i].enter_dead(dev, i);
68 * cpuidle_enter_state - enter the state and update stats
69 * @dev: cpuidle device for this cpu
70 * @drv: cpuidle driver for this cpu
71 * @next_state: index into drv->states of the state to enter
73 int cpuidle_enter_state(struct cpuidle_device *dev, struct cpuidle_driver *drv,
78 struct cpuidle_state *target_state = &drv->states[index];
79 ktime_t time_start, time_end;
82 time_start = ktime_get();
84 entered_state = target_state->enter(dev, drv, index);
86 time_end = ktime_get();
90 diff = ktime_to_us(ktime_sub(time_end, time_start));
94 dev->last_residency = (int) diff;
96 if (entered_state >= 0) {
97 /* Update cpuidle counters */
98 /* This can be moved to within driver enter routine
99 * but that results in multiple copies of same code.
101 dev->states_usage[entered_state].time += dev->last_residency;
102 dev->states_usage[entered_state].usage++;
104 dev->last_residency = 0;
107 return entered_state;
111 * cpuidle_idle_call - the main idle loop
113 * NOTE: no locks or semaphores should be used here
114 * return non-zero on failure
116 int cpuidle_idle_call(void)
118 struct cpuidle_device *dev = __this_cpu_read(cpuidle_devices);
119 struct cpuidle_driver *drv;
120 int next_state, entered_state;
123 if (off || !initialized)
126 /* check if the device is ready */
127 if (!dev || !dev->enabled)
130 drv = cpuidle_get_cpu_driver(dev);
132 /* ask the governor for the next state */
133 next_state = cpuidle_curr_governor->select(drv, dev);
134 if (need_resched()) {
135 dev->last_residency = 0;
136 /* give the governor an opportunity to reflect on the outcome */
137 if (cpuidle_curr_governor->reflect)
138 cpuidle_curr_governor->reflect(dev, next_state);
143 broadcast = !!(drv->states[next_state].flags & CPUIDLE_FLAG_TIMER_STOP);
146 clockevents_notify(CLOCK_EVT_NOTIFY_BROADCAST_ENTER, &dev->cpu))
150 trace_cpu_idle_rcuidle(next_state, dev->cpu);
152 if (cpuidle_state_is_coupled(dev, drv, next_state))
153 entered_state = cpuidle_enter_state_coupled(dev, drv,
156 entered_state = cpuidle_enter_state(dev, drv, next_state);
158 trace_cpu_idle_rcuidle(PWR_EVENT_EXIT, dev->cpu);
161 clockevents_notify(CLOCK_EVT_NOTIFY_BROADCAST_EXIT, &dev->cpu);
163 /* give the governor an opportunity to reflect on the outcome */
164 if (cpuidle_curr_governor->reflect)
165 cpuidle_curr_governor->reflect(dev, entered_state);
171 * cpuidle_install_idle_handler - installs the cpuidle idle loop handler
173 void cpuidle_install_idle_handler(void)
175 if (enabled_devices) {
176 /* Make sure all changes finished before we switch to new idle */
183 * cpuidle_uninstall_idle_handler - uninstalls the cpuidle idle loop handler
185 void cpuidle_uninstall_idle_handler(void)
187 if (enabled_devices) {
189 kick_all_cpus_sync();
194 * cpuidle_pause_and_lock - temporarily disables CPUIDLE
196 void cpuidle_pause_and_lock(void)
198 mutex_lock(&cpuidle_lock);
199 cpuidle_uninstall_idle_handler();
202 EXPORT_SYMBOL_GPL(cpuidle_pause_and_lock);
205 * cpuidle_resume_and_unlock - resumes CPUIDLE operation
207 void cpuidle_resume_and_unlock(void)
209 cpuidle_install_idle_handler();
210 mutex_unlock(&cpuidle_lock);
213 EXPORT_SYMBOL_GPL(cpuidle_resume_and_unlock);
215 /* Currently used in suspend/resume path to suspend cpuidle */
216 void cpuidle_pause(void)
218 mutex_lock(&cpuidle_lock);
219 cpuidle_uninstall_idle_handler();
220 mutex_unlock(&cpuidle_lock);
223 /* Currently used in suspend/resume path to resume cpuidle */
224 void cpuidle_resume(void)
226 mutex_lock(&cpuidle_lock);
227 cpuidle_install_idle_handler();
228 mutex_unlock(&cpuidle_lock);
232 * cpuidle_enable_device - enables idle PM for a CPU
235 * This function must be called between cpuidle_pause_and_lock and
236 * cpuidle_resume_and_unlock when used externally.
238 int cpuidle_enable_device(struct cpuidle_device *dev)
241 struct cpuidle_driver *drv;
249 drv = cpuidle_get_cpu_driver(dev);
251 if (!drv || !cpuidle_curr_governor)
254 if (!dev->registered)
257 if (!dev->state_count)
258 dev->state_count = drv->state_count;
260 ret = cpuidle_add_device_sysfs(dev);
264 if (cpuidle_curr_governor->enable &&
265 (ret = cpuidle_curr_governor->enable(drv, dev)))
276 cpuidle_remove_device_sysfs(dev);
281 EXPORT_SYMBOL_GPL(cpuidle_enable_device);
284 * cpuidle_disable_device - disables idle PM for a CPU
287 * This function must be called between cpuidle_pause_and_lock and
288 * cpuidle_resume_and_unlock when used externally.
290 void cpuidle_disable_device(struct cpuidle_device *dev)
292 struct cpuidle_driver *drv = cpuidle_get_cpu_driver(dev);
294 if (!dev || !dev->enabled)
297 if (!drv || !cpuidle_curr_governor)
302 if (cpuidle_curr_governor->disable)
303 cpuidle_curr_governor->disable(drv, dev);
305 cpuidle_remove_device_sysfs(dev);
309 EXPORT_SYMBOL_GPL(cpuidle_disable_device);
311 static void __cpuidle_unregister_device(struct cpuidle_device *dev)
313 struct cpuidle_driver *drv = cpuidle_get_cpu_driver(dev);
315 list_del(&dev->device_list);
316 per_cpu(cpuidle_devices, dev->cpu) = NULL;
317 module_put(drv->owner);
320 static void __cpuidle_device_init(struct cpuidle_device *dev)
322 memset(dev->states_usage, 0, sizeof(dev->states_usage));
323 dev->last_residency = 0;
327 * __cpuidle_register_device - internal register function called before register
328 * and enable routines
331 * cpuidle_lock mutex must be held before this is called
333 static int __cpuidle_register_device(struct cpuidle_device *dev)
336 struct cpuidle_driver *drv = cpuidle_get_cpu_driver(dev);
338 if (!try_module_get(drv->owner))
341 per_cpu(cpuidle_devices, dev->cpu) = dev;
342 list_add(&dev->device_list, &cpuidle_detected_devices);
344 ret = cpuidle_coupled_register_device(dev);
346 __cpuidle_unregister_device(dev);
354 * cpuidle_register_device - registers a CPU's idle PM feature
357 int cpuidle_register_device(struct cpuidle_device *dev)
364 mutex_lock(&cpuidle_lock);
369 __cpuidle_device_init(dev);
371 ret = __cpuidle_register_device(dev);
375 ret = cpuidle_add_sysfs(dev);
379 ret = cpuidle_enable_device(dev);
383 cpuidle_install_idle_handler();
386 mutex_unlock(&cpuidle_lock);
391 cpuidle_remove_sysfs(dev);
393 __cpuidle_unregister_device(dev);
397 EXPORT_SYMBOL_GPL(cpuidle_register_device);
400 * cpuidle_unregister_device - unregisters a CPU's idle PM feature
403 void cpuidle_unregister_device(struct cpuidle_device *dev)
405 if (!dev || dev->registered == 0)
408 cpuidle_pause_and_lock();
410 cpuidle_disable_device(dev);
412 cpuidle_remove_sysfs(dev);
414 __cpuidle_unregister_device(dev);
416 cpuidle_coupled_unregister_device(dev);
418 cpuidle_resume_and_unlock();
421 EXPORT_SYMBOL_GPL(cpuidle_unregister_device);
424 * cpuidle_unregister: unregister a driver and the devices. This function
425 * can be used only if the driver has been previously registered through
426 * the cpuidle_register function.
428 * @drv: a valid pointer to a struct cpuidle_driver
430 void cpuidle_unregister(struct cpuidle_driver *drv)
433 struct cpuidle_device *device;
435 for_each_cpu(cpu, drv->cpumask) {
436 device = &per_cpu(cpuidle_dev, cpu);
437 cpuidle_unregister_device(device);
440 cpuidle_unregister_driver(drv);
442 EXPORT_SYMBOL_GPL(cpuidle_unregister);
445 * cpuidle_register: registers the driver and the cpu devices with the
446 * coupled_cpus passed as parameter. This function is used for all common
447 * initialization pattern there are in the arch specific drivers. The
448 * devices is globally defined in this file.
450 * @drv : a valid pointer to a struct cpuidle_driver
451 * @coupled_cpus: a cpumask for the coupled states
453 * Returns 0 on success, < 0 otherwise
455 int cpuidle_register(struct cpuidle_driver *drv,
456 const struct cpumask *const coupled_cpus)
459 struct cpuidle_device *device;
461 ret = cpuidle_register_driver(drv);
463 pr_err("failed to register cpuidle driver\n");
467 for_each_cpu(cpu, drv->cpumask) {
468 device = &per_cpu(cpuidle_dev, cpu);
471 #ifdef CONFIG_ARCH_NEEDS_CPU_IDLE_COUPLED
473 * On multiplatform for ARM, the coupled idle states could be
474 * enabled in the kernel even if the cpuidle driver does not
475 * use it. Note, coupled_cpus is a struct copy.
478 device->coupled_cpus = *coupled_cpus;
480 ret = cpuidle_register_device(device);
484 pr_err("Failed to register cpuidle device for cpu%d\n", cpu);
486 cpuidle_unregister(drv);
492 EXPORT_SYMBOL_GPL(cpuidle_register);
496 static void smp_callback(void *v)
498 /* we already woke the CPU up, nothing more to do */
502 * This function gets called when a part of the kernel has a new latency
503 * requirement. This means we need to get all processors out of their C-state,
504 * and then recalculate a new suitable C-state. Just do a cross-cpu IPI; that
505 * wakes them all right up.
507 static int cpuidle_latency_notify(struct notifier_block *b,
508 unsigned long l, void *v)
510 smp_call_function(smp_callback, NULL, 1);
514 static struct notifier_block cpuidle_latency_notifier = {
515 .notifier_call = cpuidle_latency_notify,
518 static inline void latency_notifier_init(struct notifier_block *n)
520 pm_qos_add_notifier(PM_QOS_CPU_DMA_LATENCY, n);
523 #else /* CONFIG_SMP */
525 #define latency_notifier_init(x) do { } while (0)
527 #endif /* CONFIG_SMP */
530 * cpuidle_init - core initializer
532 static int __init cpuidle_init(void)
536 if (cpuidle_disabled())
539 ret = cpuidle_add_interface(cpu_subsys.dev_root);
543 latency_notifier_init(&cpuidle_latency_notifier);
548 module_param(off, int, 0444);
549 core_initcall(cpuidle_init);