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 #if defined(CONFIG_ARCH_HAS_CPU_IDLE_WAIT)
44 static void cpuidle_kick_cpus(void)
48 #elif defined(CONFIG_SMP)
49 # error "Arch needs cpu_idle_wait() equivalent here"
50 #else /* !CONFIG_ARCH_HAS_CPU_IDLE_WAIT && !CONFIG_SMP */
51 static void cpuidle_kick_cpus(void) {}
54 static int __cpuidle_register_device(struct cpuidle_device *dev);
56 static inline int cpuidle_enter(struct cpuidle_device *dev,
57 struct cpuidle_driver *drv, int index)
59 struct cpuidle_state *target_state = &drv->states[index];
60 return target_state->enter(dev, drv, index);
63 static inline int cpuidle_enter_tk(struct cpuidle_device *dev,
64 struct cpuidle_driver *drv, int index)
66 return cpuidle_wrap_enter(dev, drv, index, cpuidle_enter);
69 typedef int (*cpuidle_enter_t)(struct cpuidle_device *dev,
70 struct cpuidle_driver *drv, int index);
72 static cpuidle_enter_t cpuidle_enter_ops;
75 * cpuidle_play_dead - cpu off-lining
77 * Returns in case of an error or no driver
79 int cpuidle_play_dead(void)
81 struct cpuidle_device *dev = __this_cpu_read(cpuidle_devices);
82 struct cpuidle_driver *drv = cpuidle_get_driver();
83 int i, dead_state = -1;
89 /* Find lowest-power state that supports long-term idle */
90 for (i = CPUIDLE_DRIVER_STATE_START; i < drv->state_count; i++) {
91 struct cpuidle_state *s = &drv->states[i];
93 if (s->power_usage < power_usage && s->enter_dead) {
94 power_usage = s->power_usage;
100 return drv->states[dead_state].enter_dead(dev, dead_state);
106 * cpuidle_idle_call - the main idle loop
108 * NOTE: no locks or semaphores should be used here
109 * return non-zero on failure
111 int cpuidle_idle_call(void)
113 struct cpuidle_device *dev = __this_cpu_read(cpuidle_devices);
114 struct cpuidle_driver *drv = cpuidle_get_driver();
115 int next_state, entered_state;
123 /* check if the device is ready */
124 if (!dev || !dev->enabled)
127 /* ask the governor for the next state */
128 next_state = cpuidle_curr_governor->select(drv, dev);
129 if (need_resched()) {
134 trace_power_start_rcuidle(POWER_CSTATE, next_state, dev->cpu);
135 trace_cpu_idle_rcuidle(next_state, dev->cpu);
137 entered_state = cpuidle_enter_ops(dev, drv, next_state);
139 trace_power_end_rcuidle(dev->cpu);
140 trace_cpu_idle_rcuidle(PWR_EVENT_EXIT, dev->cpu);
142 if (entered_state >= 0) {
143 /* Update cpuidle counters */
144 /* This can be moved to within driver enter routine
145 * but that results in multiple copies of same code.
147 dev->states_usage[entered_state].time +=
148 (unsigned long long)dev->last_residency;
149 dev->states_usage[entered_state].usage++;
151 dev->last_residency = 0;
154 /* give the governor an opportunity to reflect on the outcome */
155 if (cpuidle_curr_governor->reflect)
156 cpuidle_curr_governor->reflect(dev, entered_state);
162 * cpuidle_install_idle_handler - installs the cpuidle idle loop handler
164 void cpuidle_install_idle_handler(void)
166 if (enabled_devices) {
167 /* Make sure all changes finished before we switch to new idle */
174 * cpuidle_uninstall_idle_handler - uninstalls the cpuidle idle loop handler
176 void cpuidle_uninstall_idle_handler(void)
178 if (enabled_devices) {
185 * cpuidle_pause_and_lock - temporarily disables CPUIDLE
187 void cpuidle_pause_and_lock(void)
189 mutex_lock(&cpuidle_lock);
190 cpuidle_uninstall_idle_handler();
193 EXPORT_SYMBOL_GPL(cpuidle_pause_and_lock);
196 * cpuidle_resume_and_unlock - resumes CPUIDLE operation
198 void cpuidle_resume_and_unlock(void)
200 cpuidle_install_idle_handler();
201 mutex_unlock(&cpuidle_lock);
204 EXPORT_SYMBOL_GPL(cpuidle_resume_and_unlock);
207 * cpuidle_wrap_enter - performs timekeeping and irqen around enter function
208 * @dev: pointer to a valid cpuidle_device object
209 * @drv: pointer to a valid cpuidle_driver object
210 * @index: index of the target cpuidle state.
212 int cpuidle_wrap_enter(struct cpuidle_device *dev,
213 struct cpuidle_driver *drv, int index,
214 int (*enter)(struct cpuidle_device *dev,
215 struct cpuidle_driver *drv, int index))
217 ktime_t time_start, time_end;
220 time_start = ktime_get();
222 index = enter(dev, drv, index);
224 time_end = ktime_get();
228 diff = ktime_to_us(ktime_sub(time_end, time_start));
232 dev->last_residency = (int) diff;
237 #ifdef CONFIG_ARCH_HAS_CPU_RELAX
238 static int poll_idle(struct cpuidle_device *dev,
239 struct cpuidle_driver *drv, int index)
246 while (!need_resched())
250 diff = ktime_to_us(ktime_sub(t2, t1));
254 dev->last_residency = (int) diff;
259 static void poll_idle_init(struct cpuidle_driver *drv)
261 struct cpuidle_state *state = &drv->states[0];
263 snprintf(state->name, CPUIDLE_NAME_LEN, "POLL");
264 snprintf(state->desc, CPUIDLE_DESC_LEN, "CPUIDLE CORE POLL IDLE");
265 state->exit_latency = 0;
266 state->target_residency = 0;
267 state->power_usage = -1;
269 state->enter = poll_idle;
273 static void poll_idle_init(struct cpuidle_driver *drv) {}
274 #endif /* CONFIG_ARCH_HAS_CPU_RELAX */
277 * cpuidle_enable_device - enables idle PM for a CPU
280 * This function must be called between cpuidle_pause_and_lock and
281 * cpuidle_resume_and_unlock when used externally.
283 int cpuidle_enable_device(struct cpuidle_device *dev)
286 struct cpuidle_driver *drv = cpuidle_get_driver();
290 if (!drv || !cpuidle_curr_governor)
292 if (!dev->state_count)
293 dev->state_count = drv->state_count;
295 if (dev->registered == 0) {
296 ret = __cpuidle_register_device(dev);
301 cpuidle_enter_ops = drv->en_core_tk_irqen ?
302 cpuidle_enter_tk : cpuidle_enter;
306 if ((ret = cpuidle_add_state_sysfs(dev)))
309 if (cpuidle_curr_governor->enable &&
310 (ret = cpuidle_curr_governor->enable(drv, dev)))
313 for (i = 0; i < dev->state_count; i++) {
314 dev->states_usage[i].usage = 0;
315 dev->states_usage[i].time = 0;
317 dev->last_residency = 0;
327 cpuidle_remove_state_sysfs(dev);
332 EXPORT_SYMBOL_GPL(cpuidle_enable_device);
335 * cpuidle_disable_device - disables idle PM for a CPU
338 * This function must be called between cpuidle_pause_and_lock and
339 * cpuidle_resume_and_unlock when used externally.
341 void cpuidle_disable_device(struct cpuidle_device *dev)
345 if (!cpuidle_get_driver() || !cpuidle_curr_governor)
350 if (cpuidle_curr_governor->disable)
351 cpuidle_curr_governor->disable(cpuidle_get_driver(), dev);
353 cpuidle_remove_state_sysfs(dev);
357 EXPORT_SYMBOL_GPL(cpuidle_disable_device);
360 * __cpuidle_register_device - internal register function called before register
361 * and enable routines
364 * cpuidle_lock mutex must be held before this is called
366 static int __cpuidle_register_device(struct cpuidle_device *dev)
369 struct device *cpu_dev = get_cpu_device((unsigned long)dev->cpu);
370 struct cpuidle_driver *cpuidle_driver = cpuidle_get_driver();
374 if (!try_module_get(cpuidle_driver->owner))
377 init_completion(&dev->kobj_unregister);
379 per_cpu(cpuidle_devices, dev->cpu) = dev;
380 list_add(&dev->device_list, &cpuidle_detected_devices);
381 if ((ret = cpuidle_add_sysfs(cpu_dev))) {
382 module_put(cpuidle_driver->owner);
391 * cpuidle_register_device - registers a CPU's idle PM feature
394 int cpuidle_register_device(struct cpuidle_device *dev)
398 mutex_lock(&cpuidle_lock);
400 if ((ret = __cpuidle_register_device(dev))) {
401 mutex_unlock(&cpuidle_lock);
405 cpuidle_enable_device(dev);
406 cpuidle_install_idle_handler();
408 mutex_unlock(&cpuidle_lock);
414 EXPORT_SYMBOL_GPL(cpuidle_register_device);
417 * cpuidle_unregister_device - unregisters a CPU's idle PM feature
420 void cpuidle_unregister_device(struct cpuidle_device *dev)
422 struct device *cpu_dev = get_cpu_device((unsigned long)dev->cpu);
423 struct cpuidle_driver *cpuidle_driver = cpuidle_get_driver();
425 if (dev->registered == 0)
428 cpuidle_pause_and_lock();
430 cpuidle_disable_device(dev);
432 cpuidle_remove_sysfs(cpu_dev);
433 list_del(&dev->device_list);
434 wait_for_completion(&dev->kobj_unregister);
435 per_cpu(cpuidle_devices, dev->cpu) = NULL;
437 cpuidle_resume_and_unlock();
439 module_put(cpuidle_driver->owner);
442 EXPORT_SYMBOL_GPL(cpuidle_unregister_device);
446 static void smp_callback(void *v)
448 /* we already woke the CPU up, nothing more to do */
452 * This function gets called when a part of the kernel has a new latency
453 * requirement. This means we need to get all processors out of their C-state,
454 * and then recalculate a new suitable C-state. Just do a cross-cpu IPI; that
455 * wakes them all right up.
457 static int cpuidle_latency_notify(struct notifier_block *b,
458 unsigned long l, void *v)
460 smp_call_function(smp_callback, NULL, 1);
464 static struct notifier_block cpuidle_latency_notifier = {
465 .notifier_call = cpuidle_latency_notify,
468 static inline void latency_notifier_init(struct notifier_block *n)
470 pm_qos_add_notifier(PM_QOS_CPU_DMA_LATENCY, n);
473 #else /* CONFIG_SMP */
475 #define latency_notifier_init(x) do { } while (0)
477 #endif /* CONFIG_SMP */
480 * cpuidle_init - core initializer
482 static int __init cpuidle_init(void)
486 if (cpuidle_disabled())
489 ret = cpuidle_add_interface(cpu_subsys.dev_root);
493 latency_notifier_init(&cpuidle_latency_notifier);
498 module_param(off, int, 0444);
499 core_initcall(cpuidle_init);