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 <linux/suspend.h>
23 #include <linux/tick.h>
24 #include <trace/events/power.h>
28 DEFINE_PER_CPU(struct cpuidle_device
*, cpuidle_devices
);
29 DEFINE_PER_CPU(struct cpuidle_device
, cpuidle_dev
);
31 DEFINE_MUTEX(cpuidle_lock
);
32 LIST_HEAD(cpuidle_detected_devices
);
34 static int enabled_devices
;
35 static int off __read_mostly
;
36 static int initialized __read_mostly
;
38 int cpuidle_disabled(void)
42 void disable_cpuidle(void)
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_find_deepest_state - Find deepest state meeting specific conditions.
71 * @drv: cpuidle driver for the given CPU.
72 * @dev: cpuidle device for the given CPU.
73 * @freeze: Whether or not the state should be suitable for suspend-to-idle.
75 static int cpuidle_find_deepest_state(struct cpuidle_driver
*drv
,
76 struct cpuidle_device
*dev
, bool freeze
)
78 unsigned int latency_req
= 0;
79 int i
, ret
= freeze
? -1 : CPUIDLE_DRIVER_STATE_START
- 1;
81 for (i
= CPUIDLE_DRIVER_STATE_START
; i
< drv
->state_count
; i
++) {
82 struct cpuidle_state
*s
= &drv
->states
[i
];
83 struct cpuidle_state_usage
*su
= &dev
->states_usage
[i
];
85 if (s
->disabled
|| su
->disable
|| s
->exit_latency
<= latency_req
86 || (freeze
&& !s
->enter_freeze
))
89 latency_req
= s
->exit_latency
;
95 static void enter_freeze_proper(struct cpuidle_driver
*drv
,
96 struct cpuidle_device
*dev
, int index
)
100 * The state used here cannot be a "coupled" one, because the "coupled"
101 * cpuidle mechanism enables interrupts and doing that with timekeeping
102 * suspended is generally unsafe.
104 drv
->states
[index
].enter_freeze(dev
, drv
, index
);
105 WARN_ON(!irqs_disabled());
107 * timekeeping_resume() that will be called by tick_unfreeze() for the
108 * last CPU executing it calls functions containing RCU read-side
109 * critical sections, so tell RCU about that.
111 RCU_NONIDLE(tick_unfreeze());
115 * cpuidle_enter_freeze - Enter an idle state suitable for suspend-to-idle.
117 * If there are states with the ->enter_freeze callback, find the deepest of
118 * them and enter it with frozen tick. Otherwise, find the deepest state
119 * available and enter it normally.
121 void cpuidle_enter_freeze(void)
123 struct cpuidle_device
*dev
= __this_cpu_read(cpuidle_devices
);
124 struct cpuidle_driver
*drv
= cpuidle_get_cpu_driver(dev
);
128 * Find the deepest state with ->enter_freeze present, which guarantees
129 * that interrupts won't be enabled when it exits and allows the tick to
132 index
= cpuidle_find_deepest_state(drv
, dev
, true);
134 enter_freeze_proper(drv
, dev
, index
);
139 * It is not safe to freeze the tick, find the deepest state available
140 * at all and try to enter it normally.
142 index
= cpuidle_find_deepest_state(drv
, dev
, false);
144 cpuidle_enter(drv
, dev
, index
);
148 /* Interrupts are enabled again here. */
153 * cpuidle_enter_state - enter the state and update stats
154 * @dev: cpuidle device for this cpu
155 * @drv: cpuidle driver for this cpu
156 * @next_state: index into drv->states of the state to enter
158 int cpuidle_enter_state(struct cpuidle_device
*dev
, struct cpuidle_driver
*drv
,
163 struct cpuidle_state
*target_state
= &drv
->states
[index
];
164 ktime_t time_start
, time_end
;
167 trace_cpu_idle_rcuidle(index
, dev
->cpu
);
168 time_start
= ktime_get();
170 entered_state
= target_state
->enter(dev
, drv
, index
);
172 time_end
= ktime_get();
173 trace_cpu_idle_rcuidle(PWR_EVENT_EXIT
, dev
->cpu
);
175 if (!cpuidle_state_is_coupled(dev
, drv
, entered_state
))
178 diff
= ktime_to_us(ktime_sub(time_end
, time_start
));
182 dev
->last_residency
= (int) diff
;
184 if (entered_state
>= 0) {
185 /* Update cpuidle counters */
186 /* This can be moved to within driver enter routine
187 * but that results in multiple copies of same code.
189 dev
->states_usage
[entered_state
].time
+= dev
->last_residency
;
190 dev
->states_usage
[entered_state
].usage
++;
192 dev
->last_residency
= 0;
195 return entered_state
;
199 * cpuidle_select - ask the cpuidle framework to choose an idle state
201 * @drv: the cpuidle driver
202 * @dev: the cpuidle device
204 * Returns the index of the idle state.
206 int cpuidle_select(struct cpuidle_driver
*drv
, struct cpuidle_device
*dev
)
208 if (off
|| !initialized
)
211 if (!drv
|| !dev
|| !dev
->enabled
)
214 return cpuidle_curr_governor
->select(drv
, dev
);
218 * cpuidle_enter - enter into the specified idle state
220 * @drv: the cpuidle driver tied with the cpu
221 * @dev: the cpuidle device
222 * @index: the index in the idle state table
224 * Returns the index in the idle state, < 0 in case of error.
225 * The error code depends on the backend driver
227 int cpuidle_enter(struct cpuidle_driver
*drv
, struct cpuidle_device
*dev
,
230 if (cpuidle_state_is_coupled(dev
, drv
, index
))
231 return cpuidle_enter_state_coupled(dev
, drv
, index
);
232 return cpuidle_enter_state(dev
, drv
, index
);
236 * cpuidle_reflect - tell the underlying governor what was the state
239 * @dev : the cpuidle device
240 * @index: the index in the idle state table
243 void cpuidle_reflect(struct cpuidle_device
*dev
, int index
)
245 if (cpuidle_curr_governor
->reflect
)
246 cpuidle_curr_governor
->reflect(dev
, index
);
250 * cpuidle_install_idle_handler - installs the cpuidle idle loop handler
252 void cpuidle_install_idle_handler(void)
254 if (enabled_devices
) {
255 /* Make sure all changes finished before we switch to new idle */
262 * cpuidle_uninstall_idle_handler - uninstalls the cpuidle idle loop handler
264 void cpuidle_uninstall_idle_handler(void)
266 if (enabled_devices
) {
268 wake_up_all_idle_cpus();
272 * Make sure external observers (such as the scheduler)
273 * are done looking at pointed idle states.
279 * cpuidle_pause_and_lock - temporarily disables CPUIDLE
281 void cpuidle_pause_and_lock(void)
283 mutex_lock(&cpuidle_lock
);
284 cpuidle_uninstall_idle_handler();
287 EXPORT_SYMBOL_GPL(cpuidle_pause_and_lock
);
290 * cpuidle_resume_and_unlock - resumes CPUIDLE operation
292 void cpuidle_resume_and_unlock(void)
294 cpuidle_install_idle_handler();
295 mutex_unlock(&cpuidle_lock
);
298 EXPORT_SYMBOL_GPL(cpuidle_resume_and_unlock
);
300 /* Currently used in suspend/resume path to suspend cpuidle */
301 void cpuidle_pause(void)
303 mutex_lock(&cpuidle_lock
);
304 cpuidle_uninstall_idle_handler();
305 mutex_unlock(&cpuidle_lock
);
308 /* Currently used in suspend/resume path to resume cpuidle */
309 void cpuidle_resume(void)
311 mutex_lock(&cpuidle_lock
);
312 cpuidle_install_idle_handler();
313 mutex_unlock(&cpuidle_lock
);
317 * cpuidle_enable_device - enables idle PM for a CPU
320 * This function must be called between cpuidle_pause_and_lock and
321 * cpuidle_resume_and_unlock when used externally.
323 int cpuidle_enable_device(struct cpuidle_device
*dev
)
326 struct cpuidle_driver
*drv
;
334 drv
= cpuidle_get_cpu_driver(dev
);
336 if (!drv
|| !cpuidle_curr_governor
)
339 if (!dev
->registered
)
342 if (!dev
->state_count
)
343 dev
->state_count
= drv
->state_count
;
345 ret
= cpuidle_add_device_sysfs(dev
);
349 if (cpuidle_curr_governor
->enable
&&
350 (ret
= cpuidle_curr_governor
->enable(drv
, dev
)))
361 cpuidle_remove_device_sysfs(dev
);
366 EXPORT_SYMBOL_GPL(cpuidle_enable_device
);
369 * cpuidle_disable_device - disables idle PM for a CPU
372 * This function must be called between cpuidle_pause_and_lock and
373 * cpuidle_resume_and_unlock when used externally.
375 void cpuidle_disable_device(struct cpuidle_device
*dev
)
377 struct cpuidle_driver
*drv
= cpuidle_get_cpu_driver(dev
);
379 if (!dev
|| !dev
->enabled
)
382 if (!drv
|| !cpuidle_curr_governor
)
387 if (cpuidle_curr_governor
->disable
)
388 cpuidle_curr_governor
->disable(drv
, dev
);
390 cpuidle_remove_device_sysfs(dev
);
394 EXPORT_SYMBOL_GPL(cpuidle_disable_device
);
396 static void __cpuidle_unregister_device(struct cpuidle_device
*dev
)
398 struct cpuidle_driver
*drv
= cpuidle_get_cpu_driver(dev
);
400 list_del(&dev
->device_list
);
401 per_cpu(cpuidle_devices
, dev
->cpu
) = NULL
;
402 module_put(drv
->owner
);
405 static void __cpuidle_device_init(struct cpuidle_device
*dev
)
407 memset(dev
->states_usage
, 0, sizeof(dev
->states_usage
));
408 dev
->last_residency
= 0;
412 * __cpuidle_register_device - internal register function called before register
413 * and enable routines
416 * cpuidle_lock mutex must be held before this is called
418 static int __cpuidle_register_device(struct cpuidle_device
*dev
)
421 struct cpuidle_driver
*drv
= cpuidle_get_cpu_driver(dev
);
423 if (!try_module_get(drv
->owner
))
426 per_cpu(cpuidle_devices
, dev
->cpu
) = dev
;
427 list_add(&dev
->device_list
, &cpuidle_detected_devices
);
429 ret
= cpuidle_coupled_register_device(dev
);
431 __cpuidle_unregister_device(dev
);
439 * cpuidle_register_device - registers a CPU's idle PM feature
442 int cpuidle_register_device(struct cpuidle_device
*dev
)
449 mutex_lock(&cpuidle_lock
);
454 __cpuidle_device_init(dev
);
456 ret
= __cpuidle_register_device(dev
);
460 ret
= cpuidle_add_sysfs(dev
);
464 ret
= cpuidle_enable_device(dev
);
468 cpuidle_install_idle_handler();
471 mutex_unlock(&cpuidle_lock
);
476 cpuidle_remove_sysfs(dev
);
478 __cpuidle_unregister_device(dev
);
482 EXPORT_SYMBOL_GPL(cpuidle_register_device
);
485 * cpuidle_unregister_device - unregisters a CPU's idle PM feature
488 void cpuidle_unregister_device(struct cpuidle_device
*dev
)
490 if (!dev
|| dev
->registered
== 0)
493 cpuidle_pause_and_lock();
495 cpuidle_disable_device(dev
);
497 cpuidle_remove_sysfs(dev
);
499 __cpuidle_unregister_device(dev
);
501 cpuidle_coupled_unregister_device(dev
);
503 cpuidle_resume_and_unlock();
506 EXPORT_SYMBOL_GPL(cpuidle_unregister_device
);
509 * cpuidle_unregister: unregister a driver and the devices. This function
510 * can be used only if the driver has been previously registered through
511 * the cpuidle_register function.
513 * @drv: a valid pointer to a struct cpuidle_driver
515 void cpuidle_unregister(struct cpuidle_driver
*drv
)
518 struct cpuidle_device
*device
;
520 for_each_cpu(cpu
, drv
->cpumask
) {
521 device
= &per_cpu(cpuidle_dev
, cpu
);
522 cpuidle_unregister_device(device
);
525 cpuidle_unregister_driver(drv
);
527 EXPORT_SYMBOL_GPL(cpuidle_unregister
);
530 * cpuidle_register: registers the driver and the cpu devices with the
531 * coupled_cpus passed as parameter. This function is used for all common
532 * initialization pattern there are in the arch specific drivers. The
533 * devices is globally defined in this file.
535 * @drv : a valid pointer to a struct cpuidle_driver
536 * @coupled_cpus: a cpumask for the coupled states
538 * Returns 0 on success, < 0 otherwise
540 int cpuidle_register(struct cpuidle_driver
*drv
,
541 const struct cpumask
*const coupled_cpus
)
544 struct cpuidle_device
*device
;
546 ret
= cpuidle_register_driver(drv
);
548 pr_err("failed to register cpuidle driver\n");
552 for_each_cpu(cpu
, drv
->cpumask
) {
553 device
= &per_cpu(cpuidle_dev
, cpu
);
556 #ifdef CONFIG_ARCH_NEEDS_CPU_IDLE_COUPLED
558 * On multiplatform for ARM, the coupled idle states could be
559 * enabled in the kernel even if the cpuidle driver does not
560 * use it. Note, coupled_cpus is a struct copy.
563 device
->coupled_cpus
= *coupled_cpus
;
565 ret
= cpuidle_register_device(device
);
569 pr_err("Failed to register cpuidle device for cpu%d\n", cpu
);
571 cpuidle_unregister(drv
);
577 EXPORT_SYMBOL_GPL(cpuidle_register
);
582 * This function gets called when a part of the kernel has a new latency
583 * requirement. This means we need to get all processors out of their C-state,
584 * and then recalculate a new suitable C-state. Just do a cross-cpu IPI; that
585 * wakes them all right up.
587 static int cpuidle_latency_notify(struct notifier_block
*b
,
588 unsigned long l
, void *v
)
590 wake_up_all_idle_cpus();
594 static struct notifier_block cpuidle_latency_notifier
= {
595 .notifier_call
= cpuidle_latency_notify
,
598 static inline void latency_notifier_init(struct notifier_block
*n
)
600 pm_qos_add_notifier(PM_QOS_CPU_DMA_LATENCY
, n
);
603 #else /* CONFIG_SMP */
605 #define latency_notifier_init(x) do { } while (0)
607 #endif /* CONFIG_SMP */
610 * cpuidle_init - core initializer
612 static int __init
cpuidle_init(void)
616 if (cpuidle_disabled())
619 ret
= cpuidle_add_interface(cpu_subsys
.dev_root
);
623 latency_notifier_init(&cpuidle_latency_notifier
);
628 module_param(off
, int, 0444);
629 core_initcall(cpuidle_init
);