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
;
36 int cpuidle_disabled(void)
40 void disable_cpuidle(void)
45 static int __cpuidle_register_device(struct cpuidle_device
*dev
);
48 * cpuidle_play_dead - cpu off-lining
50 * Returns in case of an error or no driver
52 int cpuidle_play_dead(void)
54 struct cpuidle_device
*dev
= __this_cpu_read(cpuidle_devices
);
55 struct cpuidle_driver
*drv
= cpuidle_get_cpu_driver(dev
);
61 /* Find lowest-power state that supports long-term idle */
62 for (i
= drv
->state_count
- 1; i
>= CPUIDLE_DRIVER_STATE_START
; i
--)
63 if (drv
->states
[i
].enter_dead
)
64 return drv
->states
[i
].enter_dead(dev
, i
);
70 * cpuidle_enter_state - enter the state and update stats
71 * @dev: cpuidle device for this cpu
72 * @drv: cpuidle driver for this cpu
73 * @next_state: index into drv->states of the state to enter
75 int cpuidle_enter_state(struct cpuidle_device
*dev
, struct cpuidle_driver
*drv
,
80 struct cpuidle_state
*target_state
= &drv
->states
[index
];
81 ktime_t time_start
, time_end
;
84 time_start
= ktime_get();
86 entered_state
= target_state
->enter(dev
, drv
, index
);
88 time_end
= ktime_get();
92 diff
= ktime_to_us(ktime_sub(time_end
, time_start
));
96 dev
->last_residency
= (int) diff
;
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_cpu_idle_rcuidle(next_state
, dev
->cpu
);
149 if (drv
->states
[next_state
].flags
& CPUIDLE_FLAG_TIMER_STOP
)
150 clockevents_notify(CLOCK_EVT_NOTIFY_BROADCAST_ENTER
,
153 if (cpuidle_state_is_coupled(dev
, drv
, next_state
))
154 entered_state
= cpuidle_enter_state_coupled(dev
, drv
,
157 entered_state
= cpuidle_enter_state(dev
, drv
, next_state
);
159 if (drv
->states
[next_state
].flags
& CPUIDLE_FLAG_TIMER_STOP
)
160 clockevents_notify(CLOCK_EVT_NOTIFY_BROADCAST_EXIT
,
163 trace_cpu_idle_rcuidle(PWR_EVENT_EXIT
, dev
->cpu
);
165 /* give the governor an opportunity to reflect on the outcome */
166 if (cpuidle_curr_governor
->reflect
)
167 cpuidle_curr_governor
->reflect(dev
, entered_state
);
173 * cpuidle_install_idle_handler - installs the cpuidle idle loop handler
175 void cpuidle_install_idle_handler(void)
177 if (enabled_devices
) {
178 /* Make sure all changes finished before we switch to new idle */
185 * cpuidle_uninstall_idle_handler - uninstalls the cpuidle idle loop handler
187 void cpuidle_uninstall_idle_handler(void)
189 if (enabled_devices
) {
191 kick_all_cpus_sync();
196 * cpuidle_pause_and_lock - temporarily disables CPUIDLE
198 void cpuidle_pause_and_lock(void)
200 mutex_lock(&cpuidle_lock
);
201 cpuidle_uninstall_idle_handler();
204 EXPORT_SYMBOL_GPL(cpuidle_pause_and_lock
);
207 * cpuidle_resume_and_unlock - resumes CPUIDLE operation
209 void cpuidle_resume_and_unlock(void)
211 cpuidle_install_idle_handler();
212 mutex_unlock(&cpuidle_lock
);
215 EXPORT_SYMBOL_GPL(cpuidle_resume_and_unlock
);
217 /* Currently used in suspend/resume path to suspend cpuidle */
218 void cpuidle_pause(void)
220 mutex_lock(&cpuidle_lock
);
221 cpuidle_uninstall_idle_handler();
222 mutex_unlock(&cpuidle_lock
);
225 /* Currently used in suspend/resume path to resume cpuidle */
226 void cpuidle_resume(void)
228 mutex_lock(&cpuidle_lock
);
229 cpuidle_install_idle_handler();
230 mutex_unlock(&cpuidle_lock
);
233 #ifdef CONFIG_ARCH_HAS_CPU_RELAX
234 static int poll_idle(struct cpuidle_device
*dev
,
235 struct cpuidle_driver
*drv
, int index
)
242 while (!need_resched())
246 diff
= ktime_to_us(ktime_sub(t2
, t1
));
250 dev
->last_residency
= (int) diff
;
255 static void poll_idle_init(struct cpuidle_driver
*drv
)
257 struct cpuidle_state
*state
= &drv
->states
[0];
259 snprintf(state
->name
, CPUIDLE_NAME_LEN
, "POLL");
260 snprintf(state
->desc
, CPUIDLE_DESC_LEN
, "CPUIDLE CORE POLL IDLE");
261 state
->exit_latency
= 0;
262 state
->target_residency
= 0;
263 state
->power_usage
= -1;
265 state
->enter
= poll_idle
;
266 state
->disabled
= false;
269 static void poll_idle_init(struct cpuidle_driver
*drv
) {}
270 #endif /* CONFIG_ARCH_HAS_CPU_RELAX */
273 * cpuidle_enable_device - enables idle PM for a CPU
276 * This function must be called between cpuidle_pause_and_lock and
277 * cpuidle_resume_and_unlock when used externally.
279 int cpuidle_enable_device(struct cpuidle_device
*dev
)
282 struct cpuidle_driver
*drv
;
290 drv
= cpuidle_get_cpu_driver(dev
);
292 if (!drv
|| !cpuidle_curr_governor
)
295 if (!dev
->state_count
)
296 dev
->state_count
= drv
->state_count
;
298 if (dev
->registered
== 0) {
299 ret
= __cpuidle_register_device(dev
);
306 ret
= cpuidle_add_device_sysfs(dev
);
310 if (cpuidle_curr_governor
->enable
&&
311 (ret
= cpuidle_curr_governor
->enable(drv
, dev
)))
314 for (i
= 0; i
< dev
->state_count
; i
++) {
315 dev
->states_usage
[i
].usage
= 0;
316 dev
->states_usage
[i
].time
= 0;
318 dev
->last_residency
= 0;
328 cpuidle_remove_device_sysfs(dev
);
333 EXPORT_SYMBOL_GPL(cpuidle_enable_device
);
336 * cpuidle_disable_device - disables idle PM for a CPU
339 * This function must be called between cpuidle_pause_and_lock and
340 * cpuidle_resume_and_unlock when used externally.
342 void cpuidle_disable_device(struct cpuidle_device
*dev
)
344 struct cpuidle_driver
*drv
= cpuidle_get_cpu_driver(dev
);
346 if (!dev
|| !dev
->enabled
)
349 if (!drv
|| !cpuidle_curr_governor
)
354 if (cpuidle_curr_governor
->disable
)
355 cpuidle_curr_governor
->disable(drv
, dev
);
357 cpuidle_remove_device_sysfs(dev
);
361 EXPORT_SYMBOL_GPL(cpuidle_disable_device
);
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
);
380 ret
= cpuidle_add_sysfs(dev
);
384 ret
= cpuidle_coupled_register_device(dev
);
392 cpuidle_remove_sysfs(dev
);
394 list_del(&dev
->device_list
);
395 per_cpu(cpuidle_devices
, dev
->cpu
) = NULL
;
396 module_put(drv
->owner
);
401 * cpuidle_register_device - registers a CPU's idle PM feature
404 int cpuidle_register_device(struct cpuidle_device
*dev
)
411 mutex_lock(&cpuidle_lock
);
413 if ((ret
= __cpuidle_register_device(dev
))) {
414 mutex_unlock(&cpuidle_lock
);
418 cpuidle_enable_device(dev
);
419 cpuidle_install_idle_handler();
421 mutex_unlock(&cpuidle_lock
);
427 EXPORT_SYMBOL_GPL(cpuidle_register_device
);
430 * cpuidle_unregister_device - unregisters a CPU's idle PM feature
433 void cpuidle_unregister_device(struct cpuidle_device
*dev
)
435 struct cpuidle_driver
*drv
= cpuidle_get_cpu_driver(dev
);
437 if (dev
->registered
== 0)
440 cpuidle_pause_and_lock();
442 cpuidle_disable_device(dev
);
444 cpuidle_remove_sysfs(dev
);
445 list_del(&dev
->device_list
);
446 per_cpu(cpuidle_devices
, dev
->cpu
) = NULL
;
448 cpuidle_coupled_unregister_device(dev
);
450 cpuidle_resume_and_unlock();
452 module_put(drv
->owner
);
455 EXPORT_SYMBOL_GPL(cpuidle_unregister_device
);
458 * cpuidle_unregister: unregister a driver and the devices. This function
459 * can be used only if the driver has been previously registered through
460 * the cpuidle_register function.
462 * @drv: a valid pointer to a struct cpuidle_driver
464 void cpuidle_unregister(struct cpuidle_driver
*drv
)
467 struct cpuidle_device
*device
;
469 for_each_possible_cpu(cpu
) {
470 device
= &per_cpu(cpuidle_dev
, cpu
);
471 cpuidle_unregister_device(device
);
474 cpuidle_unregister_driver(drv
);
476 EXPORT_SYMBOL_GPL(cpuidle_unregister
);
479 * cpuidle_register: registers the driver and the cpu devices with the
480 * coupled_cpus passed as parameter. This function is used for all common
481 * initialization pattern there are in the arch specific drivers. The
482 * devices is globally defined in this file.
484 * @drv : a valid pointer to a struct cpuidle_driver
485 * @coupled_cpus: a cpumask for the coupled states
487 * Returns 0 on success, < 0 otherwise
489 int cpuidle_register(struct cpuidle_driver
*drv
,
490 const struct cpumask
*const coupled_cpus
)
493 struct cpuidle_device
*device
;
495 ret
= cpuidle_register_driver(drv
);
497 pr_err("failed to register cpuidle driver\n");
501 for_each_possible_cpu(cpu
) {
502 device
= &per_cpu(cpuidle_dev
, cpu
);
505 #ifdef CONFIG_ARCH_NEEDS_CPU_IDLE_COUPLED
507 * On multiplatform for ARM, the coupled idle states could
508 * enabled in the kernel even if the cpuidle driver does not
509 * use it. Note, coupled_cpus is a struct copy.
512 device
->coupled_cpus
= *coupled_cpus
;
514 ret
= cpuidle_register_device(device
);
518 pr_err("Failed to register cpuidle device for cpu%d\n", cpu
);
520 cpuidle_unregister(drv
);
526 EXPORT_SYMBOL_GPL(cpuidle_register
);
530 static void smp_callback(void *v
)
532 /* we already woke the CPU up, nothing more to do */
536 * This function gets called when a part of the kernel has a new latency
537 * requirement. This means we need to get all processors out of their C-state,
538 * and then recalculate a new suitable C-state. Just do a cross-cpu IPI; that
539 * wakes them all right up.
541 static int cpuidle_latency_notify(struct notifier_block
*b
,
542 unsigned long l
, void *v
)
544 smp_call_function(smp_callback
, NULL
, 1);
548 static struct notifier_block cpuidle_latency_notifier
= {
549 .notifier_call
= cpuidle_latency_notify
,
552 static inline void latency_notifier_init(struct notifier_block
*n
)
554 pm_qos_add_notifier(PM_QOS_CPU_DMA_LATENCY
, n
);
557 #else /* CONFIG_SMP */
559 #define latency_notifier_init(x) do { } while (0)
561 #endif /* CONFIG_SMP */
564 * cpuidle_init - core initializer
566 static int __init
cpuidle_init(void)
570 if (cpuidle_disabled())
573 ret
= cpuidle_add_interface(cpu_subsys
.dev_root
);
577 latency_notifier_init(&cpuidle_latency_notifier
);
582 module_param(off
, int, 0444);
583 core_initcall(cpuidle_init
);