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);
77 /* Find lowest-power state that supports long-term idle */
78 for (i = drv->state_count - 1; i >= CPUIDLE_DRIVER_STATE_START; i--)
79 if (drv->states[i].enter_dead)
80 return drv->states[i].enter_dead(dev, i);
86 * cpuidle_enter_state - enter the state and update stats
87 * @dev: cpuidle device for this cpu
88 * @drv: cpuidle driver for this cpu
89 * @next_state: index into drv->states of the state to enter
91 int cpuidle_enter_state(struct cpuidle_device *dev, struct cpuidle_driver *drv,
96 entered_state = cpuidle_enter_ops(dev, drv, next_state);
98 if (entered_state >= 0) {
99 /* Update cpuidle counters */
100 /* This can be moved to within driver enter routine
101 * but that results in multiple copies of same code.
103 dev->states_usage[entered_state].time += dev->last_residency;
104 dev->states_usage[entered_state].usage++;
106 dev->last_residency = 0;
109 return entered_state;
113 * cpuidle_idle_call - the main idle loop
115 * NOTE: no locks or semaphores should be used here
116 * return non-zero on failure
118 int cpuidle_idle_call(void)
120 struct cpuidle_device *dev = __this_cpu_read(cpuidle_devices);
121 struct cpuidle_driver *drv;
122 int next_state, entered_state;
130 /* check if the device is ready */
131 if (!dev || !dev->enabled)
134 drv = cpuidle_get_cpu_driver(dev);
136 /* ask the governor for the next state */
137 next_state = cpuidle_curr_governor->select(drv, dev);
138 if (need_resched()) {
139 dev->last_residency = 0;
140 /* give the governor an opportunity to reflect on the outcome */
141 if (cpuidle_curr_governor->reflect)
142 cpuidle_curr_governor->reflect(dev, next_state);
147 trace_power_start_rcuidle(POWER_CSTATE, next_state, dev->cpu);
148 trace_cpu_idle_rcuidle(next_state, dev->cpu);
150 if (cpuidle_state_is_coupled(dev, drv, next_state))
151 entered_state = cpuidle_enter_state_coupled(dev, drv,
154 entered_state = cpuidle_enter_state(dev, drv, next_state);
156 trace_power_end_rcuidle(dev->cpu);
157 trace_cpu_idle_rcuidle(PWR_EVENT_EXIT, dev->cpu);
159 /* give the governor an opportunity to reflect on the outcome */
160 if (cpuidle_curr_governor->reflect)
161 cpuidle_curr_governor->reflect(dev, entered_state);
167 * cpuidle_install_idle_handler - installs the cpuidle idle loop handler
169 void cpuidle_install_idle_handler(void)
171 if (enabled_devices) {
172 /* Make sure all changes finished before we switch to new idle */
179 * cpuidle_uninstall_idle_handler - uninstalls the cpuidle idle loop handler
181 void cpuidle_uninstall_idle_handler(void)
183 if (enabled_devices) {
185 kick_all_cpus_sync();
190 * cpuidle_pause_and_lock - temporarily disables CPUIDLE
192 void cpuidle_pause_and_lock(void)
194 mutex_lock(&cpuidle_lock);
195 cpuidle_uninstall_idle_handler();
198 EXPORT_SYMBOL_GPL(cpuidle_pause_and_lock);
201 * cpuidle_resume_and_unlock - resumes CPUIDLE operation
203 void cpuidle_resume_and_unlock(void)
205 cpuidle_install_idle_handler();
206 mutex_unlock(&cpuidle_lock);
209 EXPORT_SYMBOL_GPL(cpuidle_resume_and_unlock);
211 /* Currently used in suspend/resume path to suspend cpuidle */
212 void cpuidle_pause(void)
214 mutex_lock(&cpuidle_lock);
215 cpuidle_uninstall_idle_handler();
216 mutex_unlock(&cpuidle_lock);
219 /* Currently used in suspend/resume path to resume cpuidle */
220 void cpuidle_resume(void)
222 mutex_lock(&cpuidle_lock);
223 cpuidle_install_idle_handler();
224 mutex_unlock(&cpuidle_lock);
228 * cpuidle_wrap_enter - performs timekeeping and irqen around enter function
229 * @dev: pointer to a valid cpuidle_device object
230 * @drv: pointer to a valid cpuidle_driver object
231 * @index: index of the target cpuidle state.
233 int cpuidle_wrap_enter(struct cpuidle_device *dev,
234 struct cpuidle_driver *drv, int index,
235 int (*enter)(struct cpuidle_device *dev,
236 struct cpuidle_driver *drv, int index))
238 ktime_t time_start, time_end;
241 time_start = ktime_get();
243 index = enter(dev, drv, index);
245 time_end = ktime_get();
249 diff = ktime_to_us(ktime_sub(time_end, time_start));
253 dev->last_residency = (int) diff;
258 #ifdef CONFIG_ARCH_HAS_CPU_RELAX
259 static int poll_idle(struct cpuidle_device *dev,
260 struct cpuidle_driver *drv, int index)
267 while (!need_resched())
271 diff = ktime_to_us(ktime_sub(t2, t1));
275 dev->last_residency = (int) diff;
280 static void poll_idle_init(struct cpuidle_driver *drv)
282 struct cpuidle_state *state = &drv->states[0];
284 snprintf(state->name, CPUIDLE_NAME_LEN, "POLL");
285 snprintf(state->desc, CPUIDLE_DESC_LEN, "CPUIDLE CORE POLL IDLE");
286 state->exit_latency = 0;
287 state->target_residency = 0;
288 state->power_usage = -1;
290 state->enter = poll_idle;
291 state->disabled = false;
294 static void poll_idle_init(struct cpuidle_driver *drv) {}
295 #endif /* CONFIG_ARCH_HAS_CPU_RELAX */
298 * cpuidle_enable_device - enables idle PM for a CPU
301 * This function must be called between cpuidle_pause_and_lock and
302 * cpuidle_resume_and_unlock when used externally.
304 int cpuidle_enable_device(struct cpuidle_device *dev)
307 struct cpuidle_driver *drv;
315 drv = cpuidle_get_cpu_driver(dev);
317 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 ret = cpuidle_add_device_sysfs(dev);
338 if (cpuidle_curr_governor->enable &&
339 (ret = cpuidle_curr_governor->enable(drv, dev)))
342 for (i = 0; i < dev->state_count; i++) {
343 dev->states_usage[i].usage = 0;
344 dev->states_usage[i].time = 0;
346 dev->last_residency = 0;
356 cpuidle_remove_device_sysfs(dev);
361 EXPORT_SYMBOL_GPL(cpuidle_enable_device);
364 * cpuidle_disable_device - disables idle PM for a CPU
367 * This function must be called between cpuidle_pause_and_lock and
368 * cpuidle_resume_and_unlock when used externally.
370 void cpuidle_disable_device(struct cpuidle_device *dev)
372 struct cpuidle_driver *drv = cpuidle_get_cpu_driver(dev);
374 if (!dev || !dev->enabled)
377 if (!drv || !cpuidle_curr_governor)
382 if (cpuidle_curr_governor->disable)
383 cpuidle_curr_governor->disable(drv, dev);
385 cpuidle_remove_device_sysfs(dev);
389 EXPORT_SYMBOL_GPL(cpuidle_disable_device);
392 * __cpuidle_register_device - internal register function called before register
393 * and enable routines
396 * cpuidle_lock mutex must be held before this is called
398 static int __cpuidle_register_device(struct cpuidle_device *dev)
401 struct cpuidle_driver *drv = cpuidle_get_cpu_driver(dev);
403 if (!try_module_get(drv->owner))
406 per_cpu(cpuidle_devices, dev->cpu) = dev;
407 list_add(&dev->device_list, &cpuidle_detected_devices);
408 ret = cpuidle_add_sysfs(dev);
412 ret = cpuidle_coupled_register_device(dev);
420 cpuidle_remove_sysfs(dev);
422 list_del(&dev->device_list);
423 per_cpu(cpuidle_devices, dev->cpu) = NULL;
424 module_put(drv->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 cpuidle_driver *drv = cpuidle_get_cpu_driver(dev);
465 if (dev->registered == 0)
468 cpuidle_pause_and_lock();
470 cpuidle_disable_device(dev);
472 cpuidle_remove_sysfs(dev);
473 list_del(&dev->device_list);
474 per_cpu(cpuidle_devices, dev->cpu) = NULL;
476 cpuidle_coupled_unregister_device(dev);
478 cpuidle_resume_and_unlock();
480 module_put(drv->owner);
483 EXPORT_SYMBOL_GPL(cpuidle_unregister_device);
487 static void smp_callback(void *v)
489 /* we already woke the CPU up, nothing more to do */
493 * This function gets called when a part of the kernel has a new latency
494 * requirement. This means we need to get all processors out of their C-state,
495 * and then recalculate a new suitable C-state. Just do a cross-cpu IPI; that
496 * wakes them all right up.
498 static int cpuidle_latency_notify(struct notifier_block *b,
499 unsigned long l, void *v)
501 smp_call_function(smp_callback, NULL, 1);
505 static struct notifier_block cpuidle_latency_notifier = {
506 .notifier_call = cpuidle_latency_notify,
509 static inline void latency_notifier_init(struct notifier_block *n)
511 pm_qos_add_notifier(PM_QOS_CPU_DMA_LATENCY, n);
514 #else /* CONFIG_SMP */
516 #define latency_notifier_init(x) do { } while (0)
518 #endif /* CONFIG_SMP */
521 * cpuidle_init - core initializer
523 static int __init cpuidle_init(void)
527 if (cpuidle_disabled())
530 ret = cpuidle_add_interface(cpu_subsys.dev_root);
534 latency_notifier_init(&cpuidle_latency_notifier);
539 module_param(off, int, 0444);
540 core_initcall(cpuidle_init);