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_params.h>
16 #include <linux/cpu.h>
17 #include <linux/cpuidle.h>
18 #include <linux/ktime.h>
19 #include <linux/hrtimer.h>
20 #include <trace/events/power.h>
24 DEFINE_PER_CPU(struct cpuidle_device *, cpuidle_devices);
26 DEFINE_MUTEX(cpuidle_lock);
27 LIST_HEAD(cpuidle_detected_devices);
28 static void (*pm_idle_old)(void);
30 static int enabled_devices;
32 #if defined(CONFIG_ARCH_HAS_CPU_IDLE_WAIT)
33 static void cpuidle_kick_cpus(void)
37 #elif defined(CONFIG_SMP)
38 # error "Arch needs cpu_idle_wait() equivalent here"
39 #else /* !CONFIG_ARCH_HAS_CPU_IDLE_WAIT && !CONFIG_SMP */
40 static void cpuidle_kick_cpus(void) {}
43 static int __cpuidle_register_device(struct cpuidle_device *dev);
46 * cpuidle_idle_call - the main idle loop
48 * NOTE: no locks or semaphores should be used here
50 static void cpuidle_idle_call(void)
52 struct cpuidle_device *dev = __this_cpu_read(cpuidle_devices);
53 struct cpuidle_state *target_state;
56 /* check if the device is ready */
57 if (!dev || !dev->enabled) {
61 #if defined(CONFIG_ARCH_HAS_DEFAULT_IDLE)
70 /* shows regressions, re-enable for 2.6.29 */
72 * run any timers that can be run now, at this point
73 * before calculating the idle duration etc.
75 hrtimer_peek_ahead_timers();
79 * Call the device's prepare function before calling the
80 * governor's select function. ->prepare gives the device's
81 * cpuidle driver a chance to update any dynamic information
82 * of its cpuidle states for the current idle period, e.g.
83 * state availability, latencies, residencies, etc.
88 /* ask the governor for the next state */
89 next_state = cpuidle_curr_governor->select(dev);
95 target_state = &dev->states[next_state];
97 /* enter the state and update stats */
98 dev->last_state = target_state;
100 trace_power_start(POWER_CSTATE, next_state, dev->cpu);
101 trace_cpu_idle(next_state, dev->cpu);
103 dev->last_residency = target_state->enter(dev, target_state);
105 trace_power_end(dev->cpu);
106 trace_cpu_idle(PWR_EVENT_EXIT, dev->cpu);
109 target_state = dev->last_state;
111 target_state->time += (unsigned long long)dev->last_residency;
112 target_state->usage++;
114 /* give the governor an opportunity to reflect on the outcome */
115 if (cpuidle_curr_governor->reflect)
116 cpuidle_curr_governor->reflect(dev);
120 * cpuidle_install_idle_handler - installs the cpuidle idle loop handler
122 void cpuidle_install_idle_handler(void)
124 if (enabled_devices && (pm_idle != cpuidle_idle_call)) {
125 /* Make sure all changes finished before we switch to new idle */
127 pm_idle = cpuidle_idle_call;
132 * cpuidle_uninstall_idle_handler - uninstalls the cpuidle idle loop handler
134 void cpuidle_uninstall_idle_handler(void)
136 if (enabled_devices && pm_idle_old && (pm_idle != pm_idle_old)) {
137 pm_idle = pm_idle_old;
143 * cpuidle_pause_and_lock - temporarily disables CPUIDLE
145 void cpuidle_pause_and_lock(void)
147 mutex_lock(&cpuidle_lock);
148 cpuidle_uninstall_idle_handler();
151 EXPORT_SYMBOL_GPL(cpuidle_pause_and_lock);
154 * cpuidle_resume_and_unlock - resumes CPUIDLE operation
156 void cpuidle_resume_and_unlock(void)
158 cpuidle_install_idle_handler();
159 mutex_unlock(&cpuidle_lock);
162 EXPORT_SYMBOL_GPL(cpuidle_resume_and_unlock);
164 #ifdef CONFIG_ARCH_HAS_CPU_RELAX
165 static int poll_idle(struct cpuidle_device *dev, struct cpuidle_state *st)
173 while (!need_resched())
177 diff = ktime_to_us(ktime_sub(t2, t1));
185 static void poll_idle_init(struct cpuidle_device *dev)
187 struct cpuidle_state *state = &dev->states[0];
189 cpuidle_set_statedata(state, NULL);
191 snprintf(state->name, CPUIDLE_NAME_LEN, "POLL");
192 snprintf(state->desc, CPUIDLE_DESC_LEN, "CPUIDLE CORE POLL IDLE");
193 state->exit_latency = 0;
194 state->target_residency = 0;
195 state->power_usage = -1;
197 state->enter = poll_idle;
200 static void poll_idle_init(struct cpuidle_device *dev) {}
201 #endif /* CONFIG_ARCH_HAS_CPU_RELAX */
204 * cpuidle_enable_device - enables idle PM for a CPU
207 * This function must be called between cpuidle_pause_and_lock and
208 * cpuidle_resume_and_unlock when used externally.
210 int cpuidle_enable_device(struct cpuidle_device *dev)
216 if (!cpuidle_get_driver() || !cpuidle_curr_governor)
218 if (!dev->state_count)
221 if (dev->registered == 0) {
222 ret = __cpuidle_register_device(dev);
229 if ((ret = cpuidle_add_state_sysfs(dev)))
232 if (cpuidle_curr_governor->enable &&
233 (ret = cpuidle_curr_governor->enable(dev)))
236 for (i = 0; i < dev->state_count; i++) {
237 dev->states[i].usage = 0;
238 dev->states[i].time = 0;
240 dev->last_residency = 0;
241 dev->last_state = NULL;
251 cpuidle_remove_state_sysfs(dev);
256 EXPORT_SYMBOL_GPL(cpuidle_enable_device);
259 * cpuidle_disable_device - disables idle PM for a CPU
262 * This function must be called between cpuidle_pause_and_lock and
263 * cpuidle_resume_and_unlock when used externally.
265 void cpuidle_disable_device(struct cpuidle_device *dev)
269 if (!cpuidle_get_driver() || !cpuidle_curr_governor)
274 if (cpuidle_curr_governor->disable)
275 cpuidle_curr_governor->disable(dev);
277 cpuidle_remove_state_sysfs(dev);
281 EXPORT_SYMBOL_GPL(cpuidle_disable_device);
284 * __cpuidle_register_device - internal register function called before register
285 * and enable routines
288 * cpuidle_lock mutex must be held before this is called
290 static int __cpuidle_register_device(struct cpuidle_device *dev)
293 struct sys_device *sys_dev = get_cpu_sysdev((unsigned long)dev->cpu);
294 struct cpuidle_driver *cpuidle_driver = cpuidle_get_driver();
298 if (!try_module_get(cpuidle_driver->owner))
301 init_completion(&dev->kobj_unregister);
304 * cpuidle driver should set the dev->power_specified bit
305 * before registering the device if the driver provides
306 * power_usage numbers.
308 * For those devices whose ->power_specified is not set,
309 * we fill in power_usage with decreasing values as the
310 * cpuidle code has an implicit assumption that state Cn
311 * uses less power than C(n-1).
313 * With CONFIG_ARCH_HAS_CPU_RELAX, C0 is already assigned
314 * an power value of -1. So we use -2, -3, etc, for other
317 if (!dev->power_specified) {
319 for (i = CPUIDLE_DRIVER_STATE_START; i < dev->state_count; i++)
320 dev->states[i].power_usage = -1 - i;
323 per_cpu(cpuidle_devices, dev->cpu) = dev;
324 list_add(&dev->device_list, &cpuidle_detected_devices);
325 if ((ret = cpuidle_add_sysfs(sys_dev))) {
326 module_put(cpuidle_driver->owner);
335 * cpuidle_register_device - registers a CPU's idle PM feature
338 int cpuidle_register_device(struct cpuidle_device *dev)
342 mutex_lock(&cpuidle_lock);
344 if ((ret = __cpuidle_register_device(dev))) {
345 mutex_unlock(&cpuidle_lock);
349 cpuidle_enable_device(dev);
350 cpuidle_install_idle_handler();
352 mutex_unlock(&cpuidle_lock);
358 EXPORT_SYMBOL_GPL(cpuidle_register_device);
361 * cpuidle_unregister_device - unregisters a CPU's idle PM feature
364 void cpuidle_unregister_device(struct cpuidle_device *dev)
366 struct sys_device *sys_dev = get_cpu_sysdev((unsigned long)dev->cpu);
367 struct cpuidle_driver *cpuidle_driver = cpuidle_get_driver();
369 if (dev->registered == 0)
372 cpuidle_pause_and_lock();
374 cpuidle_disable_device(dev);
376 cpuidle_remove_sysfs(sys_dev);
377 list_del(&dev->device_list);
378 wait_for_completion(&dev->kobj_unregister);
379 per_cpu(cpuidle_devices, dev->cpu) = NULL;
381 cpuidle_resume_and_unlock();
383 module_put(cpuidle_driver->owner);
386 EXPORT_SYMBOL_GPL(cpuidle_unregister_device);
390 static void smp_callback(void *v)
392 /* we already woke the CPU up, nothing more to do */
396 * This function gets called when a part of the kernel has a new latency
397 * requirement. This means we need to get all processors out of their C-state,
398 * and then recalculate a new suitable C-state. Just do a cross-cpu IPI; that
399 * wakes them all right up.
401 static int cpuidle_latency_notify(struct notifier_block *b,
402 unsigned long l, void *v)
404 smp_call_function(smp_callback, NULL, 1);
408 static struct notifier_block cpuidle_latency_notifier = {
409 .notifier_call = cpuidle_latency_notify,
412 static inline void latency_notifier_init(struct notifier_block *n)
414 pm_qos_add_notifier(PM_QOS_CPU_DMA_LATENCY, n);
417 #else /* CONFIG_SMP */
419 #define latency_notifier_init(x) do { } while (0)
421 #endif /* CONFIG_SMP */
424 * cpuidle_init - core initializer
426 static int __init cpuidle_init(void)
430 pm_idle_old = pm_idle;
432 ret = cpuidle_add_class_sysfs(&cpu_sysdev_class);
436 latency_notifier_init(&cpuidle_latency_notifier);
441 core_initcall(cpuidle_init);