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_driver();
72 int i, dead_state = -1;
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 +=
113 (unsigned long long)dev->last_residency;
114 dev->states_usage[entered_state].usage++;
116 dev->last_residency = 0;
119 return entered_state;
123 * cpuidle_idle_call - the main idle loop
125 * NOTE: no locks or semaphores should be used here
126 * return non-zero on failure
128 int cpuidle_idle_call(void)
130 struct cpuidle_device *dev = __this_cpu_read(cpuidle_devices);
131 struct cpuidle_driver *drv = cpuidle_get_driver();
132 int next_state, entered_state;
140 /* check if the device is ready */
141 if (!dev || !dev->enabled)
144 /* ask the governor for the next state */
145 next_state = cpuidle_curr_governor->select(drv, dev);
146 if (need_resched()) {
151 trace_power_start_rcuidle(POWER_CSTATE, next_state, dev->cpu);
152 trace_cpu_idle_rcuidle(next_state, dev->cpu);
154 if (cpuidle_state_is_coupled(dev, drv, next_state))
155 entered_state = cpuidle_enter_state_coupled(dev, drv,
158 entered_state = cpuidle_enter_state(dev, drv, next_state);
160 trace_power_end_rcuidle(dev->cpu);
161 trace_cpu_idle_rcuidle(PWR_EVENT_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_wrap_enter - performs timekeeping and irqen around enter function
233 * @dev: pointer to a valid cpuidle_device object
234 * @drv: pointer to a valid cpuidle_driver object
235 * @index: index of the target cpuidle state.
237 int cpuidle_wrap_enter(struct cpuidle_device *dev,
238 struct cpuidle_driver *drv, int index,
239 int (*enter)(struct cpuidle_device *dev,
240 struct cpuidle_driver *drv, int index))
242 ktime_t time_start, time_end;
245 time_start = ktime_get();
247 index = enter(dev, drv, index);
249 time_end = ktime_get();
253 diff = ktime_to_us(ktime_sub(time_end, time_start));
257 dev->last_residency = (int) diff;
262 #ifdef CONFIG_ARCH_HAS_CPU_RELAX
263 static int poll_idle(struct cpuidle_device *dev,
264 struct cpuidle_driver *drv, int index)
271 while (!need_resched())
275 diff = ktime_to_us(ktime_sub(t2, t1));
279 dev->last_residency = (int) diff;
284 static void poll_idle_init(struct cpuidle_driver *drv)
286 struct cpuidle_state *state = &drv->states[0];
288 snprintf(state->name, CPUIDLE_NAME_LEN, "POLL");
289 snprintf(state->desc, CPUIDLE_DESC_LEN, "CPUIDLE CORE POLL IDLE");
290 state->exit_latency = 0;
291 state->target_residency = 0;
292 state->power_usage = -1;
294 state->enter = poll_idle;
295 state->disabled = false;
298 static void poll_idle_init(struct cpuidle_driver *drv) {}
299 #endif /* CONFIG_ARCH_HAS_CPU_RELAX */
302 * cpuidle_enable_device - enables idle PM for a CPU
305 * This function must be called between cpuidle_pause_and_lock and
306 * cpuidle_resume_and_unlock when used externally.
308 int cpuidle_enable_device(struct cpuidle_device *dev)
311 struct cpuidle_driver *drv = cpuidle_get_driver();
318 if (!drv || !cpuidle_curr_governor)
320 if (!dev->state_count)
321 dev->state_count = drv->state_count;
323 if (dev->registered == 0) {
324 ret = __cpuidle_register_device(dev);
329 cpuidle_enter_ops = drv->en_core_tk_irqen ?
330 cpuidle_enter_tk : cpuidle_enter;
334 if ((ret = cpuidle_add_state_sysfs(dev)))
337 if (cpuidle_curr_governor->enable &&
338 (ret = cpuidle_curr_governor->enable(drv, dev)))
341 for (i = 0; i < dev->state_count; i++) {
342 dev->states_usage[i].usage = 0;
343 dev->states_usage[i].time = 0;
345 dev->last_residency = 0;
355 cpuidle_remove_state_sysfs(dev);
360 EXPORT_SYMBOL_GPL(cpuidle_enable_device);
363 * cpuidle_disable_device - disables idle PM for a CPU
366 * This function must be called between cpuidle_pause_and_lock and
367 * cpuidle_resume_and_unlock when used externally.
369 void cpuidle_disable_device(struct cpuidle_device *dev)
371 if (!dev || !dev->enabled)
373 if (!cpuidle_get_driver() || !cpuidle_curr_governor)
378 if (cpuidle_curr_governor->disable)
379 cpuidle_curr_governor->disable(cpuidle_get_driver(), dev);
381 cpuidle_remove_state_sysfs(dev);
385 EXPORT_SYMBOL_GPL(cpuidle_disable_device);
388 * __cpuidle_register_device - internal register function called before register
389 * and enable routines
392 * cpuidle_lock mutex must be held before this is called
394 static int __cpuidle_register_device(struct cpuidle_device *dev)
397 struct device *cpu_dev = get_cpu_device((unsigned long)dev->cpu);
398 struct cpuidle_driver *cpuidle_driver = cpuidle_get_driver();
400 if (!try_module_get(cpuidle_driver->owner))
403 init_completion(&dev->kobj_unregister);
405 per_cpu(cpuidle_devices, dev->cpu) = dev;
406 list_add(&dev->device_list, &cpuidle_detected_devices);
407 ret = cpuidle_add_sysfs(cpu_dev);
411 ret = cpuidle_coupled_register_device(dev);
419 cpuidle_remove_sysfs(cpu_dev);
420 wait_for_completion(&dev->kobj_unregister);
422 list_del(&dev->device_list);
423 per_cpu(cpuidle_devices, dev->cpu) = NULL;
424 module_put(cpuidle_driver->owner);
429 * cpuidle_register_device - registers a CPU's idle PM feature
432 int cpuidle_register_device(struct cpuidle_device *dev)
439 mutex_lock(&cpuidle_lock);
441 if ((ret = __cpuidle_register_device(dev))) {
442 mutex_unlock(&cpuidle_lock);
446 cpuidle_enable_device(dev);
447 cpuidle_install_idle_handler();
449 mutex_unlock(&cpuidle_lock);
455 EXPORT_SYMBOL_GPL(cpuidle_register_device);
458 * cpuidle_unregister_device - unregisters a CPU's idle PM feature
461 void cpuidle_unregister_device(struct cpuidle_device *dev)
463 struct device *cpu_dev = get_cpu_device((unsigned long)dev->cpu);
464 struct cpuidle_driver *cpuidle_driver = cpuidle_get_driver();
466 if (dev->registered == 0)
469 cpuidle_pause_and_lock();
471 cpuidle_disable_device(dev);
473 cpuidle_remove_sysfs(cpu_dev);
474 list_del(&dev->device_list);
475 wait_for_completion(&dev->kobj_unregister);
476 per_cpu(cpuidle_devices, dev->cpu) = NULL;
478 cpuidle_coupled_unregister_device(dev);
480 cpuidle_resume_and_unlock();
482 module_put(cpuidle_driver->owner);
485 EXPORT_SYMBOL_GPL(cpuidle_unregister_device);
489 static void smp_callback(void *v)
491 /* we already woke the CPU up, nothing more to do */
495 * This function gets called when a part of the kernel has a new latency
496 * requirement. This means we need to get all processors out of their C-state,
497 * and then recalculate a new suitable C-state. Just do a cross-cpu IPI; that
498 * wakes them all right up.
500 static int cpuidle_latency_notify(struct notifier_block *b,
501 unsigned long l, void *v)
503 smp_call_function(smp_callback, NULL, 1);
507 static struct notifier_block cpuidle_latency_notifier = {
508 .notifier_call = cpuidle_latency_notify,
511 static inline void latency_notifier_init(struct notifier_block *n)
513 pm_qos_add_notifier(PM_QOS_CPU_DMA_LATENCY, n);
516 #else /* CONFIG_SMP */
518 #define latency_notifier_init(x) do { } while (0)
520 #endif /* CONFIG_SMP */
523 * cpuidle_init - core initializer
525 static int __init cpuidle_init(void)
529 if (cpuidle_disabled())
532 ret = cpuidle_add_interface(cpu_subsys.dev_root);
536 latency_notifier_init(&cpuidle_latency_notifier);
541 module_param(off, int, 0444);
542 core_initcall(cpuidle_init);