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.h>
16 #include <linux/cpu.h>
17 #include <linux/cpuidle.h>
18 #include <linux/ktime.h>
19 #include <linux/hrtimer.h>
20 #include <linux/module.h>
21 #include <trace/events/power.h>
25 DEFINE_PER_CPU(struct cpuidle_device
*, cpuidle_devices
);
27 DEFINE_MUTEX(cpuidle_lock
);
28 LIST_HEAD(cpuidle_detected_devices
);
30 static int enabled_devices
;
31 static int off __read_mostly
;
32 static int initialized __read_mostly
;
34 int cpuidle_disabled(void)
38 void disable_cpuidle(void)
43 static int __cpuidle_register_device(struct cpuidle_device
*dev
);
45 static inline int cpuidle_enter(struct cpuidle_device
*dev
,
46 struct cpuidle_driver
*drv
, int index
)
48 struct cpuidle_state
*target_state
= &drv
->states
[index
];
49 return target_state
->enter(dev
, drv
, index
);
52 static inline int cpuidle_enter_tk(struct cpuidle_device
*dev
,
53 struct cpuidle_driver
*drv
, int index
)
55 return cpuidle_wrap_enter(dev
, drv
, index
, cpuidle_enter
);
58 typedef int (*cpuidle_enter_t
)(struct cpuidle_device
*dev
,
59 struct cpuidle_driver
*drv
, int index
);
61 static cpuidle_enter_t cpuidle_enter_ops
;
64 * cpuidle_play_dead - cpu off-lining
66 * Returns in case of an error or no driver
68 int cpuidle_play_dead(void)
70 struct cpuidle_device
*dev
= __this_cpu_read(cpuidle_devices
);
71 struct cpuidle_driver
*drv
= cpuidle_get_cpu_driver(dev
);
72 int i
, dead_state
= -1;
78 /* Find lowest-power state that supports long-term idle */
79 for (i
= CPUIDLE_DRIVER_STATE_START
; i
< drv
->state_count
; i
++) {
80 struct cpuidle_state
*s
= &drv
->states
[i
];
82 if (s
->power_usage
< power_usage
&& s
->enter_dead
) {
83 power_usage
= s
->power_usage
;
89 return drv
->states
[dead_state
].enter_dead(dev
, dead_state
);
95 * cpuidle_enter_state - enter the state and update stats
96 * @dev: cpuidle device for this cpu
97 * @drv: cpuidle driver for this cpu
98 * @next_state: index into drv->states of the state to enter
100 int cpuidle_enter_state(struct cpuidle_device
*dev
, struct cpuidle_driver
*drv
,
105 entered_state
= cpuidle_enter_ops(dev
, drv
, next_state
);
107 if (entered_state
>= 0) {
108 /* Update cpuidle counters */
109 /* This can be moved to within driver enter routine
110 * but that results in multiple copies of same code.
112 dev
->states_usage
[entered_state
].time
+=
113 (unsigned long long)dev
->last_residency
;
114 dev
->states_usage
[entered_state
].usage
++;
116 dev
->last_residency
= 0;
119 return entered_state
;
123 * cpuidle_idle_call - the main idle loop
125 * NOTE: no locks or semaphores should be used here
126 * return non-zero on failure
128 int cpuidle_idle_call(void)
130 struct cpuidle_device
*dev
= __this_cpu_read(cpuidle_devices
);
131 struct cpuidle_driver
*drv
;
132 int next_state
, entered_state
;
140 /* check if the device is ready */
141 if (!dev
|| !dev
->enabled
)
144 drv
= cpuidle_get_cpu_driver(dev
);
146 /* ask the governor for the next state */
147 next_state
= cpuidle_curr_governor
->select(drv
, dev
);
148 if (need_resched()) {
149 dev
->last_residency
= 0;
150 /* give the governor an opportunity to reflect on the outcome */
151 if (cpuidle_curr_governor
->reflect
)
152 cpuidle_curr_governor
->reflect(dev
, next_state
);
157 trace_power_start_rcuidle(POWER_CSTATE
, next_state
, dev
->cpu
);
158 trace_cpu_idle_rcuidle(next_state
, dev
->cpu
);
160 if (cpuidle_state_is_coupled(dev
, drv
, next_state
))
161 entered_state
= cpuidle_enter_state_coupled(dev
, drv
,
164 entered_state
= cpuidle_enter_state(dev
, drv
, next_state
);
166 trace_power_end_rcuidle(dev
->cpu
);
167 trace_cpu_idle_rcuidle(PWR_EVENT_EXIT
, dev
->cpu
);
169 /* give the governor an opportunity to reflect on the outcome */
170 if (cpuidle_curr_governor
->reflect
)
171 cpuidle_curr_governor
->reflect(dev
, entered_state
);
177 * cpuidle_install_idle_handler - installs the cpuidle idle loop handler
179 void cpuidle_install_idle_handler(void)
181 if (enabled_devices
) {
182 /* Make sure all changes finished before we switch to new idle */
189 * cpuidle_uninstall_idle_handler - uninstalls the cpuidle idle loop handler
191 void cpuidle_uninstall_idle_handler(void)
193 if (enabled_devices
) {
195 kick_all_cpus_sync();
200 * cpuidle_pause_and_lock - temporarily disables CPUIDLE
202 void cpuidle_pause_and_lock(void)
204 mutex_lock(&cpuidle_lock
);
205 cpuidle_uninstall_idle_handler();
208 EXPORT_SYMBOL_GPL(cpuidle_pause_and_lock
);
211 * cpuidle_resume_and_unlock - resumes CPUIDLE operation
213 void cpuidle_resume_and_unlock(void)
215 cpuidle_install_idle_handler();
216 mutex_unlock(&cpuidle_lock
);
219 EXPORT_SYMBOL_GPL(cpuidle_resume_and_unlock
);
221 /* Currently used in suspend/resume path to suspend cpuidle */
222 void cpuidle_pause(void)
224 mutex_lock(&cpuidle_lock
);
225 cpuidle_uninstall_idle_handler();
226 mutex_unlock(&cpuidle_lock
);
229 /* Currently used in suspend/resume path to resume cpuidle */
230 void cpuidle_resume(void)
232 mutex_lock(&cpuidle_lock
);
233 cpuidle_install_idle_handler();
234 mutex_unlock(&cpuidle_lock
);
238 * cpuidle_wrap_enter - performs timekeeping and irqen around enter function
239 * @dev: pointer to a valid cpuidle_device object
240 * @drv: pointer to a valid cpuidle_driver object
241 * @index: index of the target cpuidle state.
243 int cpuidle_wrap_enter(struct cpuidle_device
*dev
,
244 struct cpuidle_driver
*drv
, int index
,
245 int (*enter
)(struct cpuidle_device
*dev
,
246 struct cpuidle_driver
*drv
, int index
))
248 ktime_t time_start
, time_end
;
251 time_start
= ktime_get();
253 index
= enter(dev
, drv
, index
);
255 time_end
= ktime_get();
259 diff
= ktime_to_us(ktime_sub(time_end
, time_start
));
263 dev
->last_residency
= (int) diff
;
268 #ifdef CONFIG_ARCH_HAS_CPU_RELAX
269 static int poll_idle(struct cpuidle_device
*dev
,
270 struct cpuidle_driver
*drv
, int index
)
277 while (!need_resched())
281 diff
= ktime_to_us(ktime_sub(t2
, t1
));
285 dev
->last_residency
= (int) diff
;
290 static void poll_idle_init(struct cpuidle_driver
*drv
)
292 struct cpuidle_state
*state
= &drv
->states
[0];
294 snprintf(state
->name
, CPUIDLE_NAME_LEN
, "POLL");
295 snprintf(state
->desc
, CPUIDLE_DESC_LEN
, "CPUIDLE CORE POLL IDLE");
296 state
->exit_latency
= 0;
297 state
->target_residency
= 0;
298 state
->power_usage
= -1;
300 state
->enter
= poll_idle
;
301 state
->disabled
= false;
304 static void poll_idle_init(struct cpuidle_driver
*drv
) {}
305 #endif /* CONFIG_ARCH_HAS_CPU_RELAX */
308 * cpuidle_enable_device - enables idle PM for a CPU
311 * This function must be called between cpuidle_pause_and_lock and
312 * cpuidle_resume_and_unlock when used externally.
314 int cpuidle_enable_device(struct cpuidle_device
*dev
)
317 struct cpuidle_driver
*drv
;
325 drv
= cpuidle_get_cpu_driver(dev
);
327 if (!drv
|| !cpuidle_curr_governor
)
330 if (!dev
->state_count
)
331 dev
->state_count
= drv
->state_count
;
333 if (dev
->registered
== 0) {
334 ret
= __cpuidle_register_device(dev
);
339 cpuidle_enter_ops
= drv
->en_core_tk_irqen
?
340 cpuidle_enter_tk
: cpuidle_enter
;
344 ret
= cpuidle_add_device_sysfs(dev
);
348 if (cpuidle_curr_governor
->enable
&&
349 (ret
= cpuidle_curr_governor
->enable(drv
, dev
)))
352 for (i
= 0; i
< dev
->state_count
; i
++) {
353 dev
->states_usage
[i
].usage
= 0;
354 dev
->states_usage
[i
].time
= 0;
356 dev
->last_residency
= 0;
366 cpuidle_remove_device_sysfs(dev
);
371 EXPORT_SYMBOL_GPL(cpuidle_enable_device
);
374 * cpuidle_disable_device - disables idle PM for a CPU
377 * This function must be called between cpuidle_pause_and_lock and
378 * cpuidle_resume_and_unlock when used externally.
380 void cpuidle_disable_device(struct cpuidle_device
*dev
)
382 struct cpuidle_driver
*drv
= cpuidle_get_cpu_driver(dev
);
384 if (!dev
|| !dev
->enabled
)
387 if (!drv
|| !cpuidle_curr_governor
)
392 if (cpuidle_curr_governor
->disable
)
393 cpuidle_curr_governor
->disable(drv
, dev
);
395 cpuidle_remove_device_sysfs(dev
);
399 EXPORT_SYMBOL_GPL(cpuidle_disable_device
);
402 * __cpuidle_register_device - internal register function called before register
403 * and enable routines
406 * cpuidle_lock mutex must be held before this is called
408 static int __cpuidle_register_device(struct cpuidle_device
*dev
)
411 struct cpuidle_driver
*drv
= cpuidle_get_cpu_driver(dev
);
413 if (!try_module_get(drv
->owner
))
416 per_cpu(cpuidle_devices
, dev
->cpu
) = dev
;
417 list_add(&dev
->device_list
, &cpuidle_detected_devices
);
418 ret
= cpuidle_add_sysfs(dev
);
422 ret
= cpuidle_coupled_register_device(dev
);
430 cpuidle_remove_sysfs(dev
);
432 list_del(&dev
->device_list
);
433 per_cpu(cpuidle_devices
, dev
->cpu
) = NULL
;
434 module_put(drv
->owner
);
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
);
451 if ((ret
= __cpuidle_register_device(dev
))) {
452 mutex_unlock(&cpuidle_lock
);
456 cpuidle_enable_device(dev
);
457 cpuidle_install_idle_handler();
459 mutex_unlock(&cpuidle_lock
);
465 EXPORT_SYMBOL_GPL(cpuidle_register_device
);
468 * cpuidle_unregister_device - unregisters a CPU's idle PM feature
471 void cpuidle_unregister_device(struct cpuidle_device
*dev
)
473 struct cpuidle_driver
*drv
= cpuidle_get_cpu_driver(dev
);
475 if (dev
->registered
== 0)
478 cpuidle_pause_and_lock();
480 cpuidle_disable_device(dev
);
482 cpuidle_remove_sysfs(dev
);
483 list_del(&dev
->device_list
);
484 per_cpu(cpuidle_devices
, dev
->cpu
) = NULL
;
486 cpuidle_coupled_unregister_device(dev
);
488 cpuidle_resume_and_unlock();
490 module_put(drv
->owner
);
493 EXPORT_SYMBOL_GPL(cpuidle_unregister_device
);
497 static void smp_callback(void *v
)
499 /* we already woke the CPU up, nothing more to do */
503 * This function gets called when a part of the kernel has a new latency
504 * requirement. This means we need to get all processors out of their C-state,
505 * and then recalculate a new suitable C-state. Just do a cross-cpu IPI; that
506 * wakes them all right up.
508 static int cpuidle_latency_notify(struct notifier_block
*b
,
509 unsigned long l
, void *v
)
511 smp_call_function(smp_callback
, NULL
, 1);
515 static struct notifier_block cpuidle_latency_notifier
= {
516 .notifier_call
= cpuidle_latency_notify
,
519 static inline void latency_notifier_init(struct notifier_block
*n
)
521 pm_qos_add_notifier(PM_QOS_CPU_DMA_LATENCY
, n
);
524 #else /* CONFIG_SMP */
526 #define latency_notifier_init(x) do { } while (0)
528 #endif /* CONFIG_SMP */
531 * cpuidle_init - core initializer
533 static int __init
cpuidle_init(void)
537 if (cpuidle_disabled())
540 ret
= cpuidle_add_interface(cpu_subsys
.dev_root
);
544 latency_notifier_init(&cpuidle_latency_notifier
);
549 module_param(off
, int, 0444);
550 core_initcall(cpuidle_init
);