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/sched/clock.h>
16 #include <linux/notifier.h>
17 #include <linux/pm_qos.h>
18 #include <linux/cpu.h>
19 #include <linux/cpuidle.h>
20 #include <linux/ktime.h>
21 #include <linux/hrtimer.h>
22 #include <linux/module.h>
23 #include <linux/suspend.h>
24 #include <linux/tick.h>
25 #include <linux/mmu_context.h>
26 #include <trace/events/power.h>
30 DEFINE_PER_CPU(struct cpuidle_device
*, cpuidle_devices
);
31 DEFINE_PER_CPU(struct cpuidle_device
, cpuidle_dev
);
33 DEFINE_MUTEX(cpuidle_lock
);
34 LIST_HEAD(cpuidle_detected_devices
);
36 static int enabled_devices
;
37 static int off __read_mostly
;
38 static int initialized __read_mostly
;
40 int cpuidle_disabled(void)
44 void disable_cpuidle(void)
49 bool cpuidle_not_available(struct cpuidle_driver
*drv
,
50 struct cpuidle_device
*dev
)
52 return off
|| !initialized
|| !drv
|| !dev
|| !dev
->enabled
;
56 * cpuidle_play_dead - cpu off-lining
58 * Returns in case of an error or no driver
60 int cpuidle_play_dead(void)
62 struct cpuidle_device
*dev
= __this_cpu_read(cpuidle_devices
);
63 struct cpuidle_driver
*drv
= cpuidle_get_cpu_driver(dev
);
69 /* Find lowest-power state that supports long-term idle */
70 for (i
= drv
->state_count
- 1; i
>= 0; i
--)
71 if (drv
->states
[i
].enter_dead
)
72 return drv
->states
[i
].enter_dead(dev
, i
);
77 static int find_deepest_state(struct cpuidle_driver
*drv
,
78 struct cpuidle_device
*dev
,
80 unsigned int forbidden_flags
,
86 for (i
= 1; i
< drv
->state_count
; i
++) {
87 struct cpuidle_state
*s
= &drv
->states
[i
];
89 if (dev
->states_usage
[i
].disable
||
90 s
->exit_latency_ns
<= latency_req
||
91 s
->exit_latency_ns
> max_latency_ns
||
92 (s
->flags
& forbidden_flags
) ||
93 (s2idle
&& !s
->enter_s2idle
))
96 latency_req
= s
->exit_latency_ns
;
103 * cpuidle_use_deepest_state - Set/unset governor override mode.
104 * @latency_limit_ns: Idle state exit latency limit (or no override if 0).
106 * If @latency_limit_ns is nonzero, set the current CPU to use the deepest idle
107 * state with exit latency within @latency_limit_ns (override governors going
108 * forward), or do not override governors if it is zero.
110 void cpuidle_use_deepest_state(u64 latency_limit_ns
)
112 struct cpuidle_device
*dev
;
115 dev
= cpuidle_get_device();
117 dev
->forced_idle_latency_limit_ns
= latency_limit_ns
;
122 * cpuidle_find_deepest_state - Find the deepest available idle state.
123 * @drv: cpuidle driver for the given CPU.
124 * @dev: cpuidle device for the given CPU.
125 * @latency_limit_ns: Idle state exit latency limit
127 * Return: the index of the deepest available idle state.
129 int cpuidle_find_deepest_state(struct cpuidle_driver
*drv
,
130 struct cpuidle_device
*dev
,
131 u64 latency_limit_ns
)
133 return find_deepest_state(drv
, dev
, latency_limit_ns
, 0, false);
136 #ifdef CONFIG_SUSPEND
137 static void enter_s2idle_proper(struct cpuidle_driver
*drv
,
138 struct cpuidle_device
*dev
, int index
)
140 ktime_t time_start
, time_end
;
141 struct cpuidle_state
*target_state
= &drv
->states
[index
];
143 time_start
= ns_to_ktime(local_clock());
147 * The state used here cannot be a "coupled" one, because the "coupled"
148 * cpuidle mechanism enables interrupts and doing that with timekeeping
149 * suspended is generally unsafe.
151 stop_critical_timings();
152 if (!(target_state
->flags
& CPUIDLE_FLAG_RCU_IDLE
))
154 target_state
->enter_s2idle(dev
, drv
, index
);
155 if (WARN_ON_ONCE(!irqs_disabled()))
157 if (!(target_state
->flags
& CPUIDLE_FLAG_RCU_IDLE
))
160 start_critical_timings();
162 time_end
= ns_to_ktime(local_clock());
164 dev
->states_usage
[index
].s2idle_time
+= ktime_us_delta(time_end
, time_start
);
165 dev
->states_usage
[index
].s2idle_usage
++;
169 * cpuidle_enter_s2idle - Enter an idle state suitable for suspend-to-idle.
170 * @drv: cpuidle driver for the given CPU.
171 * @dev: cpuidle device for the given CPU.
173 * If there are states with the ->enter_s2idle callback, find the deepest of
174 * them and enter it with frozen tick.
176 int cpuidle_enter_s2idle(struct cpuidle_driver
*drv
, struct cpuidle_device
*dev
)
181 * Find the deepest state with ->enter_s2idle present, which guarantees
182 * that interrupts won't be enabled when it exits and allows the tick to
185 index
= find_deepest_state(drv
, dev
, U64_MAX
, 0, true);
187 enter_s2idle_proper(drv
, dev
, index
);
192 #endif /* CONFIG_SUSPEND */
195 * cpuidle_enter_state - enter the state and update stats
196 * @dev: cpuidle device for this cpu
197 * @drv: cpuidle driver for this cpu
198 * @index: index into the states table in @drv of the state to enter
200 int cpuidle_enter_state(struct cpuidle_device
*dev
, struct cpuidle_driver
*drv
,
205 struct cpuidle_state
*target_state
= &drv
->states
[index
];
206 bool broadcast
= !!(target_state
->flags
& CPUIDLE_FLAG_TIMER_STOP
);
207 ktime_t time_start
, time_end
;
210 * Tell the time framework to switch to a broadcast timer because our
211 * local timer will be shut down. If a local timer is used from another
212 * CPU as a broadcast timer, this call may fail if it is not available.
214 if (broadcast
&& tick_broadcast_enter()) {
215 index
= find_deepest_state(drv
, dev
, target_state
->exit_latency_ns
,
216 CPUIDLE_FLAG_TIMER_STOP
, false);
221 target_state
= &drv
->states
[index
];
225 if (target_state
->flags
& CPUIDLE_FLAG_TLB_FLUSHED
)
228 /* Take note of the planned idle state. */
229 sched_idle_set_state(target_state
);
231 trace_cpu_idle(index
, dev
->cpu
);
232 time_start
= ns_to_ktime(local_clock());
234 stop_critical_timings();
235 if (!(target_state
->flags
& CPUIDLE_FLAG_RCU_IDLE
))
237 entered_state
= target_state
->enter(dev
, drv
, index
);
238 if (!(target_state
->flags
& CPUIDLE_FLAG_RCU_IDLE
))
240 start_critical_timings();
242 sched_clock_idle_wakeup_event();
243 time_end
= ns_to_ktime(local_clock());
244 trace_cpu_idle(PWR_EVENT_EXIT
, dev
->cpu
);
246 /* The cpu is no longer idle or about to enter idle. */
247 sched_idle_set_state(NULL
);
250 if (WARN_ON_ONCE(!irqs_disabled()))
253 tick_broadcast_exit();
256 if (!cpuidle_state_is_coupled(drv
, index
))
259 if (entered_state
>= 0) {
260 s64 diff
, delay
= drv
->states
[entered_state
].exit_latency_ns
;
264 * Update cpuidle counters
265 * This can be moved to within driver enter routine,
266 * but that results in multiple copies of same code.
268 diff
= ktime_sub(time_end
, time_start
);
270 dev
->last_residency_ns
= diff
;
271 dev
->states_usage
[entered_state
].time_ns
+= diff
;
272 dev
->states_usage
[entered_state
].usage
++;
274 if (diff
< drv
->states
[entered_state
].target_residency_ns
) {
275 for (i
= entered_state
- 1; i
>= 0; i
--) {
276 if (dev
->states_usage
[i
].disable
)
279 /* Shallower states are enabled, so update. */
280 dev
->states_usage
[entered_state
].above
++;
283 } else if (diff
> delay
) {
284 for (i
= entered_state
+ 1; i
< drv
->state_count
; i
++) {
285 if (dev
->states_usage
[i
].disable
)
289 * Update if a deeper state would have been a
290 * better match for the observed idle duration.
292 if (diff
- delay
>= drv
->states
[i
].target_residency_ns
)
293 dev
->states_usage
[entered_state
].below
++;
299 dev
->last_residency_ns
= 0;
300 dev
->states_usage
[index
].rejected
++;
303 return entered_state
;
307 * cpuidle_select - ask the cpuidle framework to choose an idle state
309 * @drv: the cpuidle driver
310 * @dev: the cpuidle device
311 * @stop_tick: indication on whether or not to stop the tick
313 * Returns the index of the idle state. The return value must not be negative.
315 * The memory location pointed to by @stop_tick is expected to be written the
316 * 'false' boolean value if the scheduler tick should not be stopped before
317 * entering the returned state.
319 int cpuidle_select(struct cpuidle_driver
*drv
, struct cpuidle_device
*dev
,
322 return cpuidle_curr_governor
->select(drv
, dev
, stop_tick
);
326 * cpuidle_enter - enter into the specified idle state
328 * @drv: the cpuidle driver tied with the cpu
329 * @dev: the cpuidle device
330 * @index: the index in the idle state table
332 * Returns the index in the idle state, < 0 in case of error.
333 * The error code depends on the backend driver
335 int cpuidle_enter(struct cpuidle_driver
*drv
, struct cpuidle_device
*dev
,
341 * Store the next hrtimer, which becomes either next tick or the next
342 * timer event, whatever expires first. Additionally, to make this data
343 * useful for consumers outside cpuidle, we rely on that the governor's
344 * ->select() callback have decided, whether to stop the tick or not.
346 WRITE_ONCE(dev
->next_hrtimer
, tick_nohz_get_next_hrtimer());
348 if (cpuidle_state_is_coupled(drv
, index
))
349 ret
= cpuidle_enter_state_coupled(dev
, drv
, index
);
351 ret
= cpuidle_enter_state(dev
, drv
, index
);
353 WRITE_ONCE(dev
->next_hrtimer
, 0);
358 * cpuidle_reflect - tell the underlying governor what was the state
361 * @dev : the cpuidle device
362 * @index: the index in the idle state table
365 void cpuidle_reflect(struct cpuidle_device
*dev
, int index
)
367 if (cpuidle_curr_governor
->reflect
&& index
>= 0)
368 cpuidle_curr_governor
->reflect(dev
, index
);
372 * cpuidle_poll_time - return amount of time to poll for,
373 * governors can override dev->poll_limit_ns if necessary
375 * @drv: the cpuidle driver tied with the cpu
376 * @dev: the cpuidle device
379 u64
cpuidle_poll_time(struct cpuidle_driver
*drv
,
380 struct cpuidle_device
*dev
)
385 if (dev
->poll_limit_ns
)
386 return dev
->poll_limit_ns
;
388 limit_ns
= TICK_NSEC
;
389 for (i
= 1; i
< drv
->state_count
; i
++) {
390 if (dev
->states_usage
[i
].disable
)
393 limit_ns
= drv
->states
[i
].target_residency_ns
;
397 dev
->poll_limit_ns
= limit_ns
;
399 return dev
->poll_limit_ns
;
403 * cpuidle_install_idle_handler - installs the cpuidle idle loop handler
405 void cpuidle_install_idle_handler(void)
407 if (enabled_devices
) {
408 /* Make sure all changes finished before we switch to new idle */
415 * cpuidle_uninstall_idle_handler - uninstalls the cpuidle idle loop handler
417 void cpuidle_uninstall_idle_handler(void)
419 if (enabled_devices
) {
421 wake_up_all_idle_cpus();
425 * Make sure external observers (such as the scheduler)
426 * are done looking at pointed idle states.
432 * cpuidle_pause_and_lock - temporarily disables CPUIDLE
434 void cpuidle_pause_and_lock(void)
436 mutex_lock(&cpuidle_lock
);
437 cpuidle_uninstall_idle_handler();
440 EXPORT_SYMBOL_GPL(cpuidle_pause_and_lock
);
443 * cpuidle_resume_and_unlock - resumes CPUIDLE operation
445 void cpuidle_resume_and_unlock(void)
447 cpuidle_install_idle_handler();
448 mutex_unlock(&cpuidle_lock
);
451 EXPORT_SYMBOL_GPL(cpuidle_resume_and_unlock
);
453 /* Currently used in suspend/resume path to suspend cpuidle */
454 void cpuidle_pause(void)
456 mutex_lock(&cpuidle_lock
);
457 cpuidle_uninstall_idle_handler();
458 mutex_unlock(&cpuidle_lock
);
461 /* Currently used in suspend/resume path to resume cpuidle */
462 void cpuidle_resume(void)
464 mutex_lock(&cpuidle_lock
);
465 cpuidle_install_idle_handler();
466 mutex_unlock(&cpuidle_lock
);
470 * cpuidle_enable_device - enables idle PM for a CPU
473 * This function must be called between cpuidle_pause_and_lock and
474 * cpuidle_resume_and_unlock when used externally.
476 int cpuidle_enable_device(struct cpuidle_device
*dev
)
479 struct cpuidle_driver
*drv
;
487 if (!cpuidle_curr_governor
)
490 drv
= cpuidle_get_cpu_driver(dev
);
495 if (!dev
->registered
)
498 ret
= cpuidle_add_device_sysfs(dev
);
502 if (cpuidle_curr_governor
->enable
) {
503 ret
= cpuidle_curr_governor
->enable(drv
, dev
);
516 cpuidle_remove_device_sysfs(dev
);
521 EXPORT_SYMBOL_GPL(cpuidle_enable_device
);
524 * cpuidle_disable_device - disables idle PM for a CPU
527 * This function must be called between cpuidle_pause_and_lock and
528 * cpuidle_resume_and_unlock when used externally.
530 void cpuidle_disable_device(struct cpuidle_device
*dev
)
532 struct cpuidle_driver
*drv
= cpuidle_get_cpu_driver(dev
);
534 if (!dev
|| !dev
->enabled
)
537 if (!drv
|| !cpuidle_curr_governor
)
542 if (cpuidle_curr_governor
->disable
)
543 cpuidle_curr_governor
->disable(drv
, dev
);
545 cpuidle_remove_device_sysfs(dev
);
549 EXPORT_SYMBOL_GPL(cpuidle_disable_device
);
551 static void __cpuidle_unregister_device(struct cpuidle_device
*dev
)
553 struct cpuidle_driver
*drv
= cpuidle_get_cpu_driver(dev
);
555 list_del(&dev
->device_list
);
556 per_cpu(cpuidle_devices
, dev
->cpu
) = NULL
;
557 module_put(drv
->owner
);
562 static void __cpuidle_device_init(struct cpuidle_device
*dev
)
564 memset(dev
->states_usage
, 0, sizeof(dev
->states_usage
));
565 dev
->last_residency_ns
= 0;
566 dev
->next_hrtimer
= 0;
570 * __cpuidle_register_device - internal register function called before register
571 * and enable routines
574 * cpuidle_lock mutex must be held before this is called
576 static int __cpuidle_register_device(struct cpuidle_device
*dev
)
578 struct cpuidle_driver
*drv
= cpuidle_get_cpu_driver(dev
);
581 if (!try_module_get(drv
->owner
))
584 for (i
= 0; i
< drv
->state_count
; i
++) {
585 if (drv
->states
[i
].flags
& CPUIDLE_FLAG_UNUSABLE
)
586 dev
->states_usage
[i
].disable
|= CPUIDLE_STATE_DISABLED_BY_DRIVER
;
588 if (drv
->states
[i
].flags
& CPUIDLE_FLAG_OFF
)
589 dev
->states_usage
[i
].disable
|= CPUIDLE_STATE_DISABLED_BY_USER
;
592 per_cpu(cpuidle_devices
, dev
->cpu
) = dev
;
593 list_add(&dev
->device_list
, &cpuidle_detected_devices
);
595 ret
= cpuidle_coupled_register_device(dev
);
597 __cpuidle_unregister_device(dev
);
605 * cpuidle_register_device - registers a CPU's idle PM feature
608 int cpuidle_register_device(struct cpuidle_device
*dev
)
615 mutex_lock(&cpuidle_lock
);
620 __cpuidle_device_init(dev
);
622 ret
= __cpuidle_register_device(dev
);
626 ret
= cpuidle_add_sysfs(dev
);
630 ret
= cpuidle_enable_device(dev
);
634 cpuidle_install_idle_handler();
637 mutex_unlock(&cpuidle_lock
);
642 cpuidle_remove_sysfs(dev
);
644 __cpuidle_unregister_device(dev
);
648 EXPORT_SYMBOL_GPL(cpuidle_register_device
);
651 * cpuidle_unregister_device - unregisters a CPU's idle PM feature
654 void cpuidle_unregister_device(struct cpuidle_device
*dev
)
656 if (!dev
|| dev
->registered
== 0)
659 cpuidle_pause_and_lock();
661 cpuidle_disable_device(dev
);
663 cpuidle_remove_sysfs(dev
);
665 __cpuidle_unregister_device(dev
);
667 cpuidle_coupled_unregister_device(dev
);
669 cpuidle_resume_and_unlock();
672 EXPORT_SYMBOL_GPL(cpuidle_unregister_device
);
675 * cpuidle_unregister: unregister a driver and the devices. This function
676 * can be used only if the driver has been previously registered through
677 * the cpuidle_register function.
679 * @drv: a valid pointer to a struct cpuidle_driver
681 void cpuidle_unregister(struct cpuidle_driver
*drv
)
684 struct cpuidle_device
*device
;
686 for_each_cpu(cpu
, drv
->cpumask
) {
687 device
= &per_cpu(cpuidle_dev
, cpu
);
688 cpuidle_unregister_device(device
);
691 cpuidle_unregister_driver(drv
);
693 EXPORT_SYMBOL_GPL(cpuidle_unregister
);
696 * cpuidle_register: registers the driver and the cpu devices with the
697 * coupled_cpus passed as parameter. This function is used for all common
698 * initialization pattern there are in the arch specific drivers. The
699 * devices is globally defined in this file.
701 * @drv : a valid pointer to a struct cpuidle_driver
702 * @coupled_cpus: a cpumask for the coupled states
704 * Returns 0 on success, < 0 otherwise
706 int cpuidle_register(struct cpuidle_driver
*drv
,
707 const struct cpumask
*const coupled_cpus
)
710 struct cpuidle_device
*device
;
712 ret
= cpuidle_register_driver(drv
);
714 pr_err("failed to register cpuidle driver\n");
718 for_each_cpu(cpu
, drv
->cpumask
) {
719 device
= &per_cpu(cpuidle_dev
, cpu
);
722 #ifdef CONFIG_ARCH_NEEDS_CPU_IDLE_COUPLED
724 * On multiplatform for ARM, the coupled idle states could be
725 * enabled in the kernel even if the cpuidle driver does not
726 * use it. Note, coupled_cpus is a struct copy.
729 device
->coupled_cpus
= *coupled_cpus
;
731 ret
= cpuidle_register_device(device
);
735 pr_err("Failed to register cpuidle device for cpu%d\n", cpu
);
737 cpuidle_unregister(drv
);
743 EXPORT_SYMBOL_GPL(cpuidle_register
);
746 * cpuidle_init - core initializer
748 static int __init
cpuidle_init(void)
750 if (cpuidle_disabled())
753 return cpuidle_add_interface(cpu_subsys
.dev_root
);
756 module_param(off
, int, 0444);
757 module_param_string(governor
, param_governor
, CPUIDLE_NAME_LEN
, 0444);
758 core_initcall(cpuidle_init
);