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/clockchips.h>
12 #include <linux/kernel.h>
13 #include <linux/mutex.h>
14 #include <linux/sched.h>
15 #include <linux/notifier.h>
16 #include <linux/pm_qos.h>
17 #include <linux/cpu.h>
18 #include <linux/cpuidle.h>
19 #include <linux/ktime.h>
20 #include <linux/hrtimer.h>
21 #include <linux/module.h>
22 #include <trace/events/power.h>
26 DEFINE_PER_CPU(struct cpuidle_device *, cpuidle_devices);
27 DEFINE_PER_CPU(struct cpuidle_device, cpuidle_dev);
29 DEFINE_MUTEX(cpuidle_lock);
30 LIST_HEAD(cpuidle_detected_devices);
32 static int enabled_devices;
33 static int off __read_mostly;
34 static int initialized __read_mostly;
35 static bool use_deepest_state __read_mostly;
37 int cpuidle_disabled(void)
41 void disable_cpuidle(void)
47 * cpuidle_play_dead - cpu off-lining
49 * Returns in case of an error or no driver
51 int cpuidle_play_dead(void)
53 struct cpuidle_device *dev = __this_cpu_read(cpuidle_devices);
54 struct cpuidle_driver *drv = cpuidle_get_cpu_driver(dev);
60 /* Find lowest-power state that supports long-term idle */
61 for (i = drv->state_count - 1; i >= CPUIDLE_DRIVER_STATE_START; i--)
62 if (drv->states[i].enter_dead)
63 return drv->states[i].enter_dead(dev, i);
69 * cpuidle_use_deepest_state - Enable/disable the "deepest idle" mode.
70 * @enable: Whether enable or disable the feature.
72 * If the "deepest idle" mode is enabled, cpuidle will ignore the governor and
73 * always use the state with the greatest exit latency (out of the states that
76 * This function can only be called after cpuidle_pause() to avoid races.
78 void cpuidle_use_deepest_state(bool enable)
80 use_deepest_state = enable;
84 * cpuidle_find_deepest_state - Find the state of the greatest exit latency.
85 * @drv: cpuidle driver for a given CPU.
86 * @dev: cpuidle device for a given CPU.
88 static int cpuidle_find_deepest_state(struct cpuidle_driver *drv,
89 struct cpuidle_device *dev)
91 unsigned int latency_req = 0;
92 int i, ret = CPUIDLE_DRIVER_STATE_START - 1;
94 for (i = CPUIDLE_DRIVER_STATE_START; i < drv->state_count; i++) {
95 struct cpuidle_state *s = &drv->states[i];
96 struct cpuidle_state_usage *su = &dev->states_usage[i];
98 if (s->disabled || su->disable || s->exit_latency <= latency_req)
101 latency_req = s->exit_latency;
108 * cpuidle_enter_state - enter the state and update stats
109 * @dev: cpuidle device for this cpu
110 * @drv: cpuidle driver for this cpu
111 * @next_state: index into drv->states of the state to enter
113 int cpuidle_enter_state(struct cpuidle_device *dev, struct cpuidle_driver *drv,
118 struct cpuidle_state *target_state = &drv->states[index];
119 ktime_t time_start, time_end;
122 trace_cpu_idle_rcuidle(index, dev->cpu);
123 time_start = ktime_get();
125 entered_state = target_state->enter(dev, drv, index);
127 time_end = ktime_get();
128 trace_cpu_idle_rcuidle(PWR_EVENT_EXIT, dev->cpu);
130 if (!cpuidle_state_is_coupled(dev, drv, entered_state))
133 diff = ktime_to_us(ktime_sub(time_end, time_start));
137 dev->last_residency = (int) diff;
139 if (entered_state >= 0) {
140 /* Update cpuidle counters */
141 /* This can be moved to within driver enter routine
142 * but that results in multiple copies of same code.
144 dev->states_usage[entered_state].time += dev->last_residency;
145 dev->states_usage[entered_state].usage++;
147 dev->last_residency = 0;
150 return entered_state;
154 * cpuidle_select - ask the cpuidle framework to choose an idle state
156 * @drv: the cpuidle driver
157 * @dev: the cpuidle device
159 * Returns the index of the idle state.
161 int cpuidle_select(struct cpuidle_driver *drv, struct cpuidle_device *dev)
163 if (off || !initialized)
166 if (!drv || !dev || !dev->enabled)
169 if (unlikely(use_deepest_state))
170 return cpuidle_find_deepest_state(drv, dev);
172 return cpuidle_curr_governor->select(drv, dev);
176 * cpuidle_enter - enter into the specified idle state
178 * @drv: the cpuidle driver tied with the cpu
179 * @dev: the cpuidle device
180 * @index: the index in the idle state table
182 * Returns the index in the idle state, < 0 in case of error.
183 * The error code depends on the backend driver
185 int cpuidle_enter(struct cpuidle_driver *drv, struct cpuidle_device *dev,
188 if (cpuidle_state_is_coupled(dev, drv, index))
189 return cpuidle_enter_state_coupled(dev, drv, index);
190 return cpuidle_enter_state(dev, drv, index);
194 * cpuidle_reflect - tell the underlying governor what was the state
197 * @dev : the cpuidle device
198 * @index: the index in the idle state table
201 void cpuidle_reflect(struct cpuidle_device *dev, int index)
203 if (cpuidle_curr_governor->reflect && !unlikely(use_deepest_state))
204 cpuidle_curr_governor->reflect(dev, index);
208 * cpuidle_install_idle_handler - installs the cpuidle idle loop handler
210 void cpuidle_install_idle_handler(void)
212 if (enabled_devices) {
213 /* Make sure all changes finished before we switch to new idle */
220 * cpuidle_uninstall_idle_handler - uninstalls the cpuidle idle loop handler
222 void cpuidle_uninstall_idle_handler(void)
224 if (enabled_devices) {
226 kick_all_cpus_sync();
231 * cpuidle_pause_and_lock - temporarily disables CPUIDLE
233 void cpuidle_pause_and_lock(void)
235 mutex_lock(&cpuidle_lock);
236 cpuidle_uninstall_idle_handler();
239 EXPORT_SYMBOL_GPL(cpuidle_pause_and_lock);
242 * cpuidle_resume_and_unlock - resumes CPUIDLE operation
244 void cpuidle_resume_and_unlock(void)
246 cpuidle_install_idle_handler();
247 mutex_unlock(&cpuidle_lock);
250 EXPORT_SYMBOL_GPL(cpuidle_resume_and_unlock);
252 /* Currently used in suspend/resume path to suspend cpuidle */
253 void cpuidle_pause(void)
255 mutex_lock(&cpuidle_lock);
256 cpuidle_uninstall_idle_handler();
257 mutex_unlock(&cpuidle_lock);
260 /* Currently used in suspend/resume path to resume cpuidle */
261 void cpuidle_resume(void)
263 mutex_lock(&cpuidle_lock);
264 cpuidle_install_idle_handler();
265 mutex_unlock(&cpuidle_lock);
269 * cpuidle_enable_device - enables idle PM for a CPU
272 * This function must be called between cpuidle_pause_and_lock and
273 * cpuidle_resume_and_unlock when used externally.
275 int cpuidle_enable_device(struct cpuidle_device *dev)
278 struct cpuidle_driver *drv;
286 drv = cpuidle_get_cpu_driver(dev);
288 if (!drv || !cpuidle_curr_governor)
291 if (!dev->registered)
294 if (!dev->state_count)
295 dev->state_count = drv->state_count;
297 ret = cpuidle_add_device_sysfs(dev);
301 if (cpuidle_curr_governor->enable &&
302 (ret = cpuidle_curr_governor->enable(drv, dev)))
313 cpuidle_remove_device_sysfs(dev);
318 EXPORT_SYMBOL_GPL(cpuidle_enable_device);
321 * cpuidle_disable_device - disables idle PM for a CPU
324 * This function must be called between cpuidle_pause_and_lock and
325 * cpuidle_resume_and_unlock when used externally.
327 void cpuidle_disable_device(struct cpuidle_device *dev)
329 struct cpuidle_driver *drv = cpuidle_get_cpu_driver(dev);
331 if (!dev || !dev->enabled)
334 if (!drv || !cpuidle_curr_governor)
339 if (cpuidle_curr_governor->disable)
340 cpuidle_curr_governor->disable(drv, dev);
342 cpuidle_remove_device_sysfs(dev);
346 EXPORT_SYMBOL_GPL(cpuidle_disable_device);
348 static void __cpuidle_unregister_device(struct cpuidle_device *dev)
350 struct cpuidle_driver *drv = cpuidle_get_cpu_driver(dev);
352 list_del(&dev->device_list);
353 per_cpu(cpuidle_devices, dev->cpu) = NULL;
354 module_put(drv->owner);
357 static void __cpuidle_device_init(struct cpuidle_device *dev)
359 memset(dev->states_usage, 0, sizeof(dev->states_usage));
360 dev->last_residency = 0;
364 * __cpuidle_register_device - internal register function called before register
365 * and enable routines
368 * cpuidle_lock mutex must be held before this is called
370 static int __cpuidle_register_device(struct cpuidle_device *dev)
373 struct cpuidle_driver *drv = cpuidle_get_cpu_driver(dev);
375 if (!try_module_get(drv->owner))
378 per_cpu(cpuidle_devices, dev->cpu) = dev;
379 list_add(&dev->device_list, &cpuidle_detected_devices);
381 ret = cpuidle_coupled_register_device(dev);
383 __cpuidle_unregister_device(dev);
391 * cpuidle_register_device - registers a CPU's idle PM feature
394 int cpuidle_register_device(struct cpuidle_device *dev)
401 mutex_lock(&cpuidle_lock);
406 __cpuidle_device_init(dev);
408 ret = __cpuidle_register_device(dev);
412 ret = cpuidle_add_sysfs(dev);
416 ret = cpuidle_enable_device(dev);
420 cpuidle_install_idle_handler();
423 mutex_unlock(&cpuidle_lock);
428 cpuidle_remove_sysfs(dev);
430 __cpuidle_unregister_device(dev);
434 EXPORT_SYMBOL_GPL(cpuidle_register_device);
437 * cpuidle_unregister_device - unregisters a CPU's idle PM feature
440 void cpuidle_unregister_device(struct cpuidle_device *dev)
442 if (!dev || dev->registered == 0)
445 cpuidle_pause_and_lock();
447 cpuidle_disable_device(dev);
449 cpuidle_remove_sysfs(dev);
451 __cpuidle_unregister_device(dev);
453 cpuidle_coupled_unregister_device(dev);
455 cpuidle_resume_and_unlock();
458 EXPORT_SYMBOL_GPL(cpuidle_unregister_device);
461 * cpuidle_unregister: unregister a driver and the devices. This function
462 * can be used only if the driver has been previously registered through
463 * the cpuidle_register function.
465 * @drv: a valid pointer to a struct cpuidle_driver
467 void cpuidle_unregister(struct cpuidle_driver *drv)
470 struct cpuidle_device *device;
472 for_each_cpu(cpu, drv->cpumask) {
473 device = &per_cpu(cpuidle_dev, cpu);
474 cpuidle_unregister_device(device);
477 cpuidle_unregister_driver(drv);
479 EXPORT_SYMBOL_GPL(cpuidle_unregister);
482 * cpuidle_register: registers the driver and the cpu devices with the
483 * coupled_cpus passed as parameter. This function is used for all common
484 * initialization pattern there are in the arch specific drivers. The
485 * devices is globally defined in this file.
487 * @drv : a valid pointer to a struct cpuidle_driver
488 * @coupled_cpus: a cpumask for the coupled states
490 * Returns 0 on success, < 0 otherwise
492 int cpuidle_register(struct cpuidle_driver *drv,
493 const struct cpumask *const coupled_cpus)
496 struct cpuidle_device *device;
498 ret = cpuidle_register_driver(drv);
500 pr_err("failed to register cpuidle driver\n");
504 for_each_cpu(cpu, drv->cpumask) {
505 device = &per_cpu(cpuidle_dev, cpu);
508 #ifdef CONFIG_ARCH_NEEDS_CPU_IDLE_COUPLED
510 * On multiplatform for ARM, the coupled idle states could be
511 * enabled in the kernel even if the cpuidle driver does not
512 * use it. Note, coupled_cpus is a struct copy.
515 device->coupled_cpus = *coupled_cpus;
517 ret = cpuidle_register_device(device);
521 pr_err("Failed to register cpuidle device for cpu%d\n", cpu);
523 cpuidle_unregister(drv);
529 EXPORT_SYMBOL_GPL(cpuidle_register);
533 static void smp_callback(void *v)
535 /* we already woke the CPU up, nothing more to do */
539 * This function gets called when a part of the kernel has a new latency
540 * requirement. This means we need to get all processors out of their C-state,
541 * and then recalculate a new suitable C-state. Just do a cross-cpu IPI; that
542 * wakes them all right up.
544 static int cpuidle_latency_notify(struct notifier_block *b,
545 unsigned long l, void *v)
547 smp_call_function(smp_callback, NULL, 1);
551 static struct notifier_block cpuidle_latency_notifier = {
552 .notifier_call = cpuidle_latency_notify,
555 static inline void latency_notifier_init(struct notifier_block *n)
557 pm_qos_add_notifier(PM_QOS_CPU_DMA_LATENCY, n);
560 #else /* CONFIG_SMP */
562 #define latency_notifier_init(x) do { } while (0)
564 #endif /* CONFIG_SMP */
567 * cpuidle_init - core initializer
569 static int __init cpuidle_init(void)
573 if (cpuidle_disabled())
576 ret = cpuidle_add_interface(cpu_subsys.dev_root);
580 latency_notifier_init(&cpuidle_latency_notifier);
585 module_param(off, int, 0444);
586 core_initcall(cpuidle_init);