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 #if defined(CONFIG_ARCH_HAS_CPU_IDLE_WAIT)
44 static void cpuidle_kick_cpus(void)
48 #elif defined(CONFIG_SMP)
49 # error "Arch needs cpu_idle_wait() equivalent here"
50 #else /* !CONFIG_ARCH_HAS_CPU_IDLE_WAIT && !CONFIG_SMP */
51 static void cpuidle_kick_cpus(void) {}
54 static int __cpuidle_register_device(struct cpuidle_device
*dev
);
56 static inline int cpuidle_enter(struct cpuidle_device
*dev
,
57 struct cpuidle_driver
*drv
, int index
)
59 struct cpuidle_state
*target_state
= &drv
->states
[index
];
60 return target_state
->enter(dev
, drv
, index
);
63 static inline int cpuidle_enter_tk(struct cpuidle_device
*dev
,
64 struct cpuidle_driver
*drv
, int index
)
66 return cpuidle_wrap_enter(dev
, drv
, index
, cpuidle_enter
);
69 typedef int (*cpuidle_enter_t
)(struct cpuidle_device
*dev
,
70 struct cpuidle_driver
*drv
, int index
);
72 static cpuidle_enter_t cpuidle_enter_ops
;
75 * cpuidle_play_dead - cpu off-lining
77 * Returns in case of an error or no driver
79 int cpuidle_play_dead(void)
81 struct cpuidle_device
*dev
= __this_cpu_read(cpuidle_devices
);
82 struct cpuidle_driver
*drv
= cpuidle_get_driver();
83 int i
, dead_state
= -1;
89 /* Find lowest-power state that supports long-term idle */
90 for (i
= CPUIDLE_DRIVER_STATE_START
; i
< drv
->state_count
; i
++) {
91 struct cpuidle_state
*s
= &drv
->states
[i
];
93 if (s
->power_usage
< power_usage
&& s
->enter_dead
) {
94 power_usage
= s
->power_usage
;
100 return drv
->states
[dead_state
].enter_dead(dev
, dead_state
);
106 * cpuidle_idle_call - the main idle loop
108 * NOTE: no locks or semaphores should be used here
109 * return non-zero on failure
111 int cpuidle_idle_call(void)
113 struct cpuidle_device
*dev
= __this_cpu_read(cpuidle_devices
);
114 struct cpuidle_driver
*drv
= cpuidle_get_driver();
115 int next_state
, entered_state
;
123 /* check if the device is ready */
124 if (!dev
|| !dev
->enabled
)
128 /* shows regressions, re-enable for 2.6.29 */
130 * run any timers that can be run now, at this point
131 * before calculating the idle duration etc.
133 hrtimer_peek_ahead_timers();
136 /* ask the governor for the next state */
137 next_state
= cpuidle_curr_governor
->select(drv
, dev
);
138 if (need_resched()) {
143 trace_power_start_rcuidle(POWER_CSTATE
, next_state
, dev
->cpu
);
144 trace_cpu_idle_rcuidle(next_state
, dev
->cpu
);
146 entered_state
= cpuidle_enter_ops(dev
, drv
, next_state
);
148 trace_power_end_rcuidle(dev
->cpu
);
149 trace_cpu_idle_rcuidle(PWR_EVENT_EXIT
, dev
->cpu
);
151 if (entered_state
>= 0) {
152 /* Update cpuidle counters */
153 /* This can be moved to within driver enter routine
154 * but that results in multiple copies of same code.
156 dev
->states_usage
[entered_state
].time
+=
157 (unsigned long long)dev
->last_residency
;
158 dev
->states_usage
[entered_state
].usage
++;
160 dev
->last_residency
= 0;
163 /* give the governor an opportunity to reflect on the outcome */
164 if (cpuidle_curr_governor
->reflect
)
165 cpuidle_curr_governor
->reflect(dev
, entered_state
);
171 * cpuidle_install_idle_handler - installs the cpuidle idle loop handler
173 void cpuidle_install_idle_handler(void)
175 if (enabled_devices
) {
176 /* Make sure all changes finished before we switch to new idle */
183 * cpuidle_uninstall_idle_handler - uninstalls the cpuidle idle loop handler
185 void cpuidle_uninstall_idle_handler(void)
187 if (enabled_devices
) {
194 * cpuidle_pause_and_lock - temporarily disables CPUIDLE
196 void cpuidle_pause_and_lock(void)
198 mutex_lock(&cpuidle_lock
);
199 cpuidle_uninstall_idle_handler();
202 EXPORT_SYMBOL_GPL(cpuidle_pause_and_lock
);
205 * cpuidle_resume_and_unlock - resumes CPUIDLE operation
207 void cpuidle_resume_and_unlock(void)
209 cpuidle_install_idle_handler();
210 mutex_unlock(&cpuidle_lock
);
213 EXPORT_SYMBOL_GPL(cpuidle_resume_and_unlock
);
216 * cpuidle_wrap_enter - performs timekeeping and irqen around enter function
217 * @dev: pointer to a valid cpuidle_device object
218 * @drv: pointer to a valid cpuidle_driver object
219 * @index: index of the target cpuidle state.
221 int cpuidle_wrap_enter(struct cpuidle_device
*dev
,
222 struct cpuidle_driver
*drv
, int index
,
223 int (*enter
)(struct cpuidle_device
*dev
,
224 struct cpuidle_driver
*drv
, int index
))
226 ktime_t time_start
, time_end
;
229 time_start
= ktime_get();
231 index
= enter(dev
, drv
, index
);
233 time_end
= ktime_get();
237 diff
= ktime_to_us(ktime_sub(time_end
, time_start
));
241 dev
->last_residency
= (int) diff
;
246 #ifdef CONFIG_ARCH_HAS_CPU_RELAX
247 static int poll_idle(struct cpuidle_device
*dev
,
248 struct cpuidle_driver
*drv
, int index
)
255 while (!need_resched())
259 diff
= ktime_to_us(ktime_sub(t2
, t1
));
263 dev
->last_residency
= (int) diff
;
268 static void poll_idle_init(struct cpuidle_driver
*drv
)
270 struct cpuidle_state
*state
= &drv
->states
[0];
272 snprintf(state
->name
, CPUIDLE_NAME_LEN
, "POLL");
273 snprintf(state
->desc
, CPUIDLE_DESC_LEN
, "CPUIDLE CORE POLL IDLE");
274 state
->exit_latency
= 0;
275 state
->target_residency
= 0;
276 state
->power_usage
= -1;
278 state
->enter
= poll_idle
;
282 static void poll_idle_init(struct cpuidle_driver
*drv
) {}
283 #endif /* CONFIG_ARCH_HAS_CPU_RELAX */
286 * cpuidle_enable_device - enables idle PM for a CPU
289 * This function must be called between cpuidle_pause_and_lock and
290 * cpuidle_resume_and_unlock when used externally.
292 int cpuidle_enable_device(struct cpuidle_device
*dev
)
295 struct cpuidle_driver
*drv
= cpuidle_get_driver();
299 if (!drv
|| !cpuidle_curr_governor
)
301 if (!dev
->state_count
)
302 dev
->state_count
= drv
->state_count
;
304 if (dev
->registered
== 0) {
305 ret
= __cpuidle_register_device(dev
);
310 cpuidle_enter_ops
= drv
->en_core_tk_irqen
?
311 cpuidle_enter_tk
: cpuidle_enter
;
315 if ((ret
= cpuidle_add_state_sysfs(dev
)))
318 if (cpuidle_curr_governor
->enable
&&
319 (ret
= cpuidle_curr_governor
->enable(drv
, dev
)))
322 for (i
= 0; i
< dev
->state_count
; i
++) {
323 dev
->states_usage
[i
].usage
= 0;
324 dev
->states_usage
[i
].time
= 0;
326 dev
->last_residency
= 0;
336 cpuidle_remove_state_sysfs(dev
);
341 EXPORT_SYMBOL_GPL(cpuidle_enable_device
);
344 * cpuidle_disable_device - disables idle PM for a CPU
347 * This function must be called between cpuidle_pause_and_lock and
348 * cpuidle_resume_and_unlock when used externally.
350 void cpuidle_disable_device(struct cpuidle_device
*dev
)
354 if (!cpuidle_get_driver() || !cpuidle_curr_governor
)
359 if (cpuidle_curr_governor
->disable
)
360 cpuidle_curr_governor
->disable(cpuidle_get_driver(), dev
);
362 cpuidle_remove_state_sysfs(dev
);
366 EXPORT_SYMBOL_GPL(cpuidle_disable_device
);
369 * __cpuidle_register_device - internal register function called before register
370 * and enable routines
373 * cpuidle_lock mutex must be held before this is called
375 static int __cpuidle_register_device(struct cpuidle_device
*dev
)
378 struct device
*cpu_dev
= get_cpu_device((unsigned long)dev
->cpu
);
379 struct cpuidle_driver
*cpuidle_driver
= cpuidle_get_driver();
383 if (!try_module_get(cpuidle_driver
->owner
))
386 init_completion(&dev
->kobj_unregister
);
388 per_cpu(cpuidle_devices
, dev
->cpu
) = dev
;
389 list_add(&dev
->device_list
, &cpuidle_detected_devices
);
390 if ((ret
= cpuidle_add_sysfs(cpu_dev
))) {
391 module_put(cpuidle_driver
->owner
);
400 * cpuidle_register_device - registers a CPU's idle PM feature
403 int cpuidle_register_device(struct cpuidle_device
*dev
)
407 mutex_lock(&cpuidle_lock
);
409 if ((ret
= __cpuidle_register_device(dev
))) {
410 mutex_unlock(&cpuidle_lock
);
414 cpuidle_enable_device(dev
);
415 cpuidle_install_idle_handler();
417 mutex_unlock(&cpuidle_lock
);
423 EXPORT_SYMBOL_GPL(cpuidle_register_device
);
426 * cpuidle_unregister_device - unregisters a CPU's idle PM feature
429 void cpuidle_unregister_device(struct cpuidle_device
*dev
)
431 struct device
*cpu_dev
= get_cpu_device((unsigned long)dev
->cpu
);
432 struct cpuidle_driver
*cpuidle_driver
= cpuidle_get_driver();
434 if (dev
->registered
== 0)
437 cpuidle_pause_and_lock();
439 cpuidle_disable_device(dev
);
441 cpuidle_remove_sysfs(cpu_dev
);
442 list_del(&dev
->device_list
);
443 wait_for_completion(&dev
->kobj_unregister
);
444 per_cpu(cpuidle_devices
, dev
->cpu
) = NULL
;
446 cpuidle_resume_and_unlock();
448 module_put(cpuidle_driver
->owner
);
451 EXPORT_SYMBOL_GPL(cpuidle_unregister_device
);
455 static void smp_callback(void *v
)
457 /* we already woke the CPU up, nothing more to do */
461 * This function gets called when a part of the kernel has a new latency
462 * requirement. This means we need to get all processors out of their C-state,
463 * and then recalculate a new suitable C-state. Just do a cross-cpu IPI; that
464 * wakes them all right up.
466 static int cpuidle_latency_notify(struct notifier_block
*b
,
467 unsigned long l
, void *v
)
469 smp_call_function(smp_callback
, NULL
, 1);
473 static struct notifier_block cpuidle_latency_notifier
= {
474 .notifier_call
= cpuidle_latency_notify
,
477 static inline void latency_notifier_init(struct notifier_block
*n
)
479 pm_qos_add_notifier(PM_QOS_CPU_DMA_LATENCY
, n
);
482 #else /* CONFIG_SMP */
484 #define latency_notifier_init(x) do { } while (0)
486 #endif /* CONFIG_SMP */
489 * cpuidle_init - core initializer
491 static int __init
cpuidle_init(void)
495 if (cpuidle_disabled())
498 ret
= cpuidle_add_interface(cpu_subsys
.dev_root
);
502 latency_notifier_init(&cpuidle_latency_notifier
);
507 module_param(off
, int, 0444);
508 core_initcall(cpuidle_init
);