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/kernel.h>
12 #include <linux/mutex.h>
13 #include <linux/sched.h>
14 #include <linux/notifier.h>
15 #include <linux/pm_qos.h>
16 #include <linux/cpu.h>
17 #include <linux/cpuidle.h>
18 #include <linux/ktime.h>
19 #include <linux/hrtimer.h>
20 #include <linux/module.h>
21 #include <trace/events/power.h>
25 DEFINE_PER_CPU(struct cpuidle_device *, cpuidle_devices);
27 DEFINE_MUTEX(cpuidle_lock);
28 LIST_HEAD(cpuidle_detected_devices);
30 static int enabled_devices;
31 static int off __read_mostly;
32 static int initialized __read_mostly;
34 int cpuidle_disabled(void)
38 void disable_cpuidle(void)
43 static int __cpuidle_register_device(struct cpuidle_device *dev);
45 static inline int cpuidle_enter(struct cpuidle_device *dev,
46 struct cpuidle_driver *drv, int index)
48 struct cpuidle_state *target_state = &drv->states[index];
49 return target_state->enter(dev, drv, index);
52 static inline int cpuidle_enter_tk(struct cpuidle_device *dev,
53 struct cpuidle_driver *drv, int index)
55 return cpuidle_wrap_enter(dev, drv, index, cpuidle_enter);
58 typedef int (*cpuidle_enter_t)(struct cpuidle_device *dev,
59 struct cpuidle_driver *drv, int index);
61 static cpuidle_enter_t cpuidle_enter_ops;
64 * cpuidle_play_dead - cpu off-lining
66 * Returns in case of an error or no driver
68 int cpuidle_play_dead(void)
70 struct cpuidle_device *dev = __this_cpu_read(cpuidle_devices);
71 struct cpuidle_driver *drv = cpuidle_get_cpu_driver(dev);
72 int i, dead_state = -1;
73 int power_usage = INT_MAX;
78 /* Find lowest-power state that supports long-term idle */
79 for (i = CPUIDLE_DRIVER_STATE_START; i < drv->state_count; i++) {
80 struct cpuidle_state *s = &drv->states[i];
82 if (s->power_usage < power_usage && s->enter_dead) {
83 power_usage = s->power_usage;
89 return drv->states[dead_state].enter_dead(dev, dead_state);
95 * cpuidle_enter_state - enter the state and update stats
96 * @dev: cpuidle device for this cpu
97 * @drv: cpuidle driver for this cpu
98 * @next_state: index into drv->states of the state to enter
100 int cpuidle_enter_state(struct cpuidle_device *dev, struct cpuidle_driver *drv,
105 entered_state = cpuidle_enter_ops(dev, drv, next_state);
107 if (entered_state >= 0) {
108 /* Update cpuidle counters */
109 /* This can be moved to within driver enter routine
110 * but that results in multiple copies of same code.
112 dev->states_usage[entered_state].time += dev->last_residency;
113 dev->states_usage[entered_state].usage++;
115 dev->last_residency = 0;
118 return entered_state;
122 * cpuidle_idle_call - the main idle loop
124 * NOTE: no locks or semaphores should be used here
125 * return non-zero on failure
127 int cpuidle_idle_call(void)
129 struct cpuidle_device *dev = __this_cpu_read(cpuidle_devices);
130 struct cpuidle_driver *drv;
131 int next_state, entered_state;
139 /* check if the device is ready */
140 if (!dev || !dev->enabled)
143 drv = cpuidle_get_cpu_driver(dev);
145 /* ask the governor for the next state */
146 next_state = cpuidle_curr_governor->select(drv, dev);
147 if (need_resched()) {
148 dev->last_residency = 0;
149 /* give the governor an opportunity to reflect on the outcome */
150 if (cpuidle_curr_governor->reflect)
151 cpuidle_curr_governor->reflect(dev, next_state);
156 trace_power_start_rcuidle(POWER_CSTATE, next_state, dev->cpu);
157 trace_cpu_idle_rcuidle(next_state, dev->cpu);
159 if (cpuidle_state_is_coupled(dev, drv, next_state))
160 entered_state = cpuidle_enter_state_coupled(dev, drv,
163 entered_state = cpuidle_enter_state(dev, drv, next_state);
165 trace_power_end_rcuidle(dev->cpu);
166 trace_cpu_idle_rcuidle(PWR_EVENT_EXIT, dev->cpu);
168 /* give the governor an opportunity to reflect on the outcome */
169 if (cpuidle_curr_governor->reflect)
170 cpuidle_curr_governor->reflect(dev, entered_state);
176 * cpuidle_install_idle_handler - installs the cpuidle idle loop handler
178 void cpuidle_install_idle_handler(void)
180 if (enabled_devices) {
181 /* Make sure all changes finished before we switch to new idle */
188 * cpuidle_uninstall_idle_handler - uninstalls the cpuidle idle loop handler
190 void cpuidle_uninstall_idle_handler(void)
192 if (enabled_devices) {
194 kick_all_cpus_sync();
199 * cpuidle_pause_and_lock - temporarily disables CPUIDLE
201 void cpuidle_pause_and_lock(void)
203 mutex_lock(&cpuidle_lock);
204 cpuidle_uninstall_idle_handler();
207 EXPORT_SYMBOL_GPL(cpuidle_pause_and_lock);
210 * cpuidle_resume_and_unlock - resumes CPUIDLE operation
212 void cpuidle_resume_and_unlock(void)
214 cpuidle_install_idle_handler();
215 mutex_unlock(&cpuidle_lock);
218 EXPORT_SYMBOL_GPL(cpuidle_resume_and_unlock);
220 /* Currently used in suspend/resume path to suspend cpuidle */
221 void cpuidle_pause(void)
223 mutex_lock(&cpuidle_lock);
224 cpuidle_uninstall_idle_handler();
225 mutex_unlock(&cpuidle_lock);
228 /* Currently used in suspend/resume path to resume cpuidle */
229 void cpuidle_resume(void)
231 mutex_lock(&cpuidle_lock);
232 cpuidle_install_idle_handler();
233 mutex_unlock(&cpuidle_lock);
237 * cpuidle_wrap_enter - performs timekeeping and irqen around enter function
238 * @dev: pointer to a valid cpuidle_device object
239 * @drv: pointer to a valid cpuidle_driver object
240 * @index: index of the target cpuidle state.
242 int cpuidle_wrap_enter(struct cpuidle_device *dev,
243 struct cpuidle_driver *drv, int index,
244 int (*enter)(struct cpuidle_device *dev,
245 struct cpuidle_driver *drv, int index))
247 ktime_t time_start, time_end;
250 time_start = ktime_get();
252 index = enter(dev, drv, index);
254 time_end = ktime_get();
258 diff = ktime_to_us(ktime_sub(time_end, time_start));
262 dev->last_residency = (int) diff;
267 #ifdef CONFIG_ARCH_HAS_CPU_RELAX
268 static int poll_idle(struct cpuidle_device *dev,
269 struct cpuidle_driver *drv, int index)
276 while (!need_resched())
280 diff = ktime_to_us(ktime_sub(t2, t1));
284 dev->last_residency = (int) diff;
289 static void poll_idle_init(struct cpuidle_driver *drv)
291 struct cpuidle_state *state = &drv->states[0];
293 snprintf(state->name, CPUIDLE_NAME_LEN, "POLL");
294 snprintf(state->desc, CPUIDLE_DESC_LEN, "CPUIDLE CORE POLL IDLE");
295 state->exit_latency = 0;
296 state->target_residency = 0;
297 state->power_usage = -1;
299 state->enter = poll_idle;
300 state->disabled = false;
303 static void poll_idle_init(struct cpuidle_driver *drv) {}
304 #endif /* CONFIG_ARCH_HAS_CPU_RELAX */
307 * cpuidle_enable_device - enables idle PM for a CPU
310 * This function must be called between cpuidle_pause_and_lock and
311 * cpuidle_resume_and_unlock when used externally.
313 int cpuidle_enable_device(struct cpuidle_device *dev)
316 struct cpuidle_driver *drv;
324 drv = cpuidle_get_cpu_driver(dev);
326 if (!drv || !cpuidle_curr_governor)
329 if (!dev->state_count)
330 dev->state_count = drv->state_count;
332 if (dev->registered == 0) {
333 ret = __cpuidle_register_device(dev);
338 cpuidle_enter_ops = drv->en_core_tk_irqen ?
339 cpuidle_enter_tk : cpuidle_enter;
343 ret = cpuidle_add_device_sysfs(dev);
347 if (cpuidle_curr_governor->enable &&
348 (ret = cpuidle_curr_governor->enable(drv, dev)))
351 for (i = 0; i < dev->state_count; i++) {
352 dev->states_usage[i].usage = 0;
353 dev->states_usage[i].time = 0;
355 dev->last_residency = 0;
365 cpuidle_remove_device_sysfs(dev);
370 EXPORT_SYMBOL_GPL(cpuidle_enable_device);
373 * cpuidle_disable_device - disables idle PM for a CPU
376 * This function must be called between cpuidle_pause_and_lock and
377 * cpuidle_resume_and_unlock when used externally.
379 void cpuidle_disable_device(struct cpuidle_device *dev)
381 struct cpuidle_driver *drv = cpuidle_get_cpu_driver(dev);
383 if (!dev || !dev->enabled)
386 if (!drv || !cpuidle_curr_governor)
391 if (cpuidle_curr_governor->disable)
392 cpuidle_curr_governor->disable(drv, dev);
394 cpuidle_remove_device_sysfs(dev);
398 EXPORT_SYMBOL_GPL(cpuidle_disable_device);
401 * __cpuidle_register_device - internal register function called before register
402 * and enable routines
405 * cpuidle_lock mutex must be held before this is called
407 static int __cpuidle_register_device(struct cpuidle_device *dev)
410 struct cpuidle_driver *drv = cpuidle_get_cpu_driver(dev);
412 if (!try_module_get(drv->owner))
415 per_cpu(cpuidle_devices, dev->cpu) = dev;
416 list_add(&dev->device_list, &cpuidle_detected_devices);
417 ret = cpuidle_add_sysfs(dev);
421 ret = cpuidle_coupled_register_device(dev);
429 cpuidle_remove_sysfs(dev);
431 list_del(&dev->device_list);
432 per_cpu(cpuidle_devices, dev->cpu) = NULL;
433 module_put(drv->owner);
438 * cpuidle_register_device - registers a CPU's idle PM feature
441 int cpuidle_register_device(struct cpuidle_device *dev)
448 mutex_lock(&cpuidle_lock);
450 if ((ret = __cpuidle_register_device(dev))) {
451 mutex_unlock(&cpuidle_lock);
455 cpuidle_enable_device(dev);
456 cpuidle_install_idle_handler();
458 mutex_unlock(&cpuidle_lock);
464 EXPORT_SYMBOL_GPL(cpuidle_register_device);
467 * cpuidle_unregister_device - unregisters a CPU's idle PM feature
470 void cpuidle_unregister_device(struct cpuidle_device *dev)
472 struct cpuidle_driver *drv = cpuidle_get_cpu_driver(dev);
474 if (dev->registered == 0)
477 cpuidle_pause_and_lock();
479 cpuidle_disable_device(dev);
481 cpuidle_remove_sysfs(dev);
482 list_del(&dev->device_list);
483 per_cpu(cpuidle_devices, dev->cpu) = NULL;
485 cpuidle_coupled_unregister_device(dev);
487 cpuidle_resume_and_unlock();
489 module_put(drv->owner);
492 EXPORT_SYMBOL_GPL(cpuidle_unregister_device);
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);