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);
57 * cpuidle_idle_call - the main idle loop
59 * NOTE: no locks or semaphores should be used here
60 * return non-zero on failure
62 int cpuidle_idle_call(void)
64 struct cpuidle_device *dev = __this_cpu_read(cpuidle_devices);
65 struct cpuidle_driver *drv = cpuidle_get_driver();
66 struct cpuidle_state *target_state;
67 int next_state, entered_state;
75 /* check if the device is ready */
76 if (!dev || !dev->enabled)
80 /* shows regressions, re-enable for 2.6.29 */
82 * run any timers that can be run now, at this point
83 * before calculating the idle duration etc.
85 hrtimer_peek_ahead_timers();
88 /* ask the governor for the next state */
89 next_state = cpuidle_curr_governor->select(drv, dev);
95 target_state = &drv->states[next_state];
97 trace_power_start(POWER_CSTATE, next_state, dev->cpu);
98 trace_cpu_idle(next_state, dev->cpu);
100 entered_state = target_state->enter(dev, drv, next_state);
102 trace_power_end(dev->cpu);
103 trace_cpu_idle(PWR_EVENT_EXIT, dev->cpu);
105 if (entered_state >= 0) {
106 /* Update cpuidle counters */
107 /* This can be moved to within driver enter routine
108 * but that results in multiple copies of same code.
110 dev->states_usage[entered_state].time +=
111 (unsigned long long)dev->last_residency;
112 dev->states_usage[entered_state].usage++;
115 /* give the governor an opportunity to reflect on the outcome */
116 if (cpuidle_curr_governor->reflect)
117 cpuidle_curr_governor->reflect(dev, entered_state);
123 * cpuidle_install_idle_handler - installs the cpuidle idle loop handler
125 void cpuidle_install_idle_handler(void)
127 if (enabled_devices) {
128 /* Make sure all changes finished before we switch to new idle */
135 * cpuidle_uninstall_idle_handler - uninstalls the cpuidle idle loop handler
137 void cpuidle_uninstall_idle_handler(void)
139 if (enabled_devices) {
146 * cpuidle_pause_and_lock - temporarily disables CPUIDLE
148 void cpuidle_pause_and_lock(void)
150 mutex_lock(&cpuidle_lock);
151 cpuidle_uninstall_idle_handler();
154 EXPORT_SYMBOL_GPL(cpuidle_pause_and_lock);
157 * cpuidle_resume_and_unlock - resumes CPUIDLE operation
159 void cpuidle_resume_and_unlock(void)
161 cpuidle_install_idle_handler();
162 mutex_unlock(&cpuidle_lock);
165 EXPORT_SYMBOL_GPL(cpuidle_resume_and_unlock);
167 #ifdef CONFIG_ARCH_HAS_CPU_RELAX
168 static int poll_idle(struct cpuidle_device *dev,
169 struct cpuidle_driver *drv, int index)
176 while (!need_resched())
180 diff = ktime_to_us(ktime_sub(t2, t1));
184 dev->last_residency = (int) diff;
189 static void poll_idle_init(struct cpuidle_driver *drv)
191 struct cpuidle_state *state = &drv->states[0];
193 snprintf(state->name, CPUIDLE_NAME_LEN, "POLL");
194 snprintf(state->desc, CPUIDLE_DESC_LEN, "CPUIDLE CORE POLL IDLE");
195 state->exit_latency = 0;
196 state->target_residency = 0;
197 state->power_usage = -1;
199 state->enter = poll_idle;
203 static void poll_idle_init(struct cpuidle_driver *drv) {}
204 #endif /* CONFIG_ARCH_HAS_CPU_RELAX */
207 * cpuidle_enable_device - enables idle PM for a CPU
210 * This function must be called between cpuidle_pause_and_lock and
211 * cpuidle_resume_and_unlock when used externally.
213 int cpuidle_enable_device(struct cpuidle_device *dev)
219 if (!cpuidle_get_driver() || !cpuidle_curr_governor)
221 if (!dev->state_count)
224 if (dev->registered == 0) {
225 ret = __cpuidle_register_device(dev);
230 poll_idle_init(cpuidle_get_driver());
232 if ((ret = cpuidle_add_state_sysfs(dev)))
235 if (cpuidle_curr_governor->enable &&
236 (ret = cpuidle_curr_governor->enable(cpuidle_get_driver(), dev)))
239 for (i = 0; i < dev->state_count; i++) {
240 dev->states_usage[i].usage = 0;
241 dev->states_usage[i].time = 0;
243 dev->last_residency = 0;
253 cpuidle_remove_state_sysfs(dev);
258 EXPORT_SYMBOL_GPL(cpuidle_enable_device);
261 * cpuidle_disable_device - disables idle PM for a CPU
264 * This function must be called between cpuidle_pause_and_lock and
265 * cpuidle_resume_and_unlock when used externally.
267 void cpuidle_disable_device(struct cpuidle_device *dev)
271 if (!cpuidle_get_driver() || !cpuidle_curr_governor)
276 if (cpuidle_curr_governor->disable)
277 cpuidle_curr_governor->disable(cpuidle_get_driver(), dev);
279 cpuidle_remove_state_sysfs(dev);
283 EXPORT_SYMBOL_GPL(cpuidle_disable_device);
286 * __cpuidle_register_device - internal register function called before register
287 * and enable routines
290 * cpuidle_lock mutex must be held before this is called
292 static int __cpuidle_register_device(struct cpuidle_device *dev)
295 struct sys_device *sys_dev = get_cpu_sysdev((unsigned long)dev->cpu);
296 struct cpuidle_driver *cpuidle_driver = cpuidle_get_driver();
300 if (!try_module_get(cpuidle_driver->owner))
303 init_completion(&dev->kobj_unregister);
305 per_cpu(cpuidle_devices, dev->cpu) = dev;
306 list_add(&dev->device_list, &cpuidle_detected_devices);
307 if ((ret = cpuidle_add_sysfs(sys_dev))) {
308 module_put(cpuidle_driver->owner);
317 * cpuidle_register_device - registers a CPU's idle PM feature
320 int cpuidle_register_device(struct cpuidle_device *dev)
324 mutex_lock(&cpuidle_lock);
326 if ((ret = __cpuidle_register_device(dev))) {
327 mutex_unlock(&cpuidle_lock);
331 cpuidle_enable_device(dev);
332 cpuidle_install_idle_handler();
334 mutex_unlock(&cpuidle_lock);
340 EXPORT_SYMBOL_GPL(cpuidle_register_device);
343 * cpuidle_unregister_device - unregisters a CPU's idle PM feature
346 void cpuidle_unregister_device(struct cpuidle_device *dev)
348 struct sys_device *sys_dev = get_cpu_sysdev((unsigned long)dev->cpu);
349 struct cpuidle_driver *cpuidle_driver = cpuidle_get_driver();
351 if (dev->registered == 0)
354 cpuidle_pause_and_lock();
356 cpuidle_disable_device(dev);
358 cpuidle_remove_sysfs(sys_dev);
359 list_del(&dev->device_list);
360 wait_for_completion(&dev->kobj_unregister);
361 per_cpu(cpuidle_devices, dev->cpu) = NULL;
363 cpuidle_resume_and_unlock();
365 module_put(cpuidle_driver->owner);
368 EXPORT_SYMBOL_GPL(cpuidle_unregister_device);
372 static void smp_callback(void *v)
374 /* we already woke the CPU up, nothing more to do */
378 * This function gets called when a part of the kernel has a new latency
379 * requirement. This means we need to get all processors out of their C-state,
380 * and then recalculate a new suitable C-state. Just do a cross-cpu IPI; that
381 * wakes them all right up.
383 static int cpuidle_latency_notify(struct notifier_block *b,
384 unsigned long l, void *v)
386 smp_call_function(smp_callback, NULL, 1);
390 static struct notifier_block cpuidle_latency_notifier = {
391 .notifier_call = cpuidle_latency_notify,
394 static inline void latency_notifier_init(struct notifier_block *n)
396 pm_qos_add_notifier(PM_QOS_CPU_DMA_LATENCY, n);
399 #else /* CONFIG_SMP */
401 #define latency_notifier_init(x) do { } while (0)
403 #endif /* CONFIG_SMP */
406 * cpuidle_init - core initializer
408 static int __init cpuidle_init(void)
412 if (cpuidle_disabled())
415 ret = cpuidle_add_class_sysfs(&cpu_sysdev_class);
419 latency_notifier_init(&cpuidle_latency_notifier);
424 module_param(off, int, 0444);
425 core_initcall(cpuidle_init);