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_params.h>
16 #include <linux/cpu.h>
17 #include <linux/cpuidle.h>
18 #include <linux/ktime.h>
19 #include <linux/hrtimer.h>
23 DEFINE_PER_CPU(struct cpuidle_device
*, cpuidle_devices
);
25 DEFINE_MUTEX(cpuidle_lock
);
26 LIST_HEAD(cpuidle_detected_devices
);
27 static void (*pm_idle_old
)(void);
29 static int enabled_devices
;
31 #if defined(CONFIG_ARCH_HAS_CPU_IDLE_WAIT)
32 static void cpuidle_kick_cpus(void)
36 #elif defined(CONFIG_SMP)
37 # error "Arch needs cpu_idle_wait() equivalent here"
38 #else /* !CONFIG_ARCH_HAS_CPU_IDLE_WAIT && !CONFIG_SMP */
39 static void cpuidle_kick_cpus(void) {}
42 static int __cpuidle_register_device(struct cpuidle_device
*dev
);
45 * cpuidle_idle_call - the main idle loop
47 * NOTE: no locks or semaphores should be used here
49 static void cpuidle_idle_call(void)
51 struct cpuidle_device
*dev
= __get_cpu_var(cpuidle_devices
);
52 struct cpuidle_state
*target_state
;
55 /* check if the device is ready */
56 if (!dev
|| !dev
->enabled
) {
60 #if defined(CONFIG_ARCH_HAS_DEFAULT_IDLE)
69 * run any timers that can be run now, at this point
70 * before calculating the idle duration etc.
72 hrtimer_peek_ahead_timers();
74 /* ask the governor for the next state */
75 next_state
= cpuidle_curr_governor
->select(dev
);
78 target_state
= &dev
->states
[next_state
];
80 /* enter the state and update stats */
81 dev
->last_state
= target_state
;
82 dev
->last_residency
= target_state
->enter(dev
, target_state
);
84 target_state
= dev
->last_state
;
86 target_state
->time
+= (unsigned long long)dev
->last_residency
;
87 target_state
->usage
++;
89 /* give the governor an opportunity to reflect on the outcome */
90 if (cpuidle_curr_governor
->reflect
)
91 cpuidle_curr_governor
->reflect(dev
);
95 * cpuidle_install_idle_handler - installs the cpuidle idle loop handler
97 void cpuidle_install_idle_handler(void)
99 if (enabled_devices
&& (pm_idle
!= cpuidle_idle_call
)) {
100 /* Make sure all changes finished before we switch to new idle */
102 pm_idle
= cpuidle_idle_call
;
107 * cpuidle_uninstall_idle_handler - uninstalls the cpuidle idle loop handler
109 void cpuidle_uninstall_idle_handler(void)
111 if (enabled_devices
&& pm_idle_old
&& (pm_idle
!= pm_idle_old
)) {
112 pm_idle
= pm_idle_old
;
118 * cpuidle_pause_and_lock - temporarily disables CPUIDLE
120 void cpuidle_pause_and_lock(void)
122 mutex_lock(&cpuidle_lock
);
123 cpuidle_uninstall_idle_handler();
126 EXPORT_SYMBOL_GPL(cpuidle_pause_and_lock
);
129 * cpuidle_resume_and_unlock - resumes CPUIDLE operation
131 void cpuidle_resume_and_unlock(void)
133 cpuidle_install_idle_handler();
134 mutex_unlock(&cpuidle_lock
);
137 EXPORT_SYMBOL_GPL(cpuidle_resume_and_unlock
);
140 * cpuidle_enable_device - enables idle PM for a CPU
143 * This function must be called between cpuidle_pause_and_lock and
144 * cpuidle_resume_and_unlock when used externally.
146 int cpuidle_enable_device(struct cpuidle_device
*dev
)
152 if (!cpuidle_curr_driver
|| !cpuidle_curr_governor
)
154 if (!dev
->state_count
)
157 if (dev
->registered
== 0) {
158 ret
= __cpuidle_register_device(dev
);
163 if ((ret
= cpuidle_add_state_sysfs(dev
)))
166 if (cpuidle_curr_governor
->enable
&&
167 (ret
= cpuidle_curr_governor
->enable(dev
)))
170 for (i
= 0; i
< dev
->state_count
; i
++) {
171 dev
->states
[i
].usage
= 0;
172 dev
->states
[i
].time
= 0;
174 dev
->last_residency
= 0;
175 dev
->last_state
= NULL
;
185 cpuidle_remove_state_sysfs(dev
);
190 EXPORT_SYMBOL_GPL(cpuidle_enable_device
);
193 * cpuidle_disable_device - disables idle PM for a CPU
196 * This function must be called between cpuidle_pause_and_lock and
197 * cpuidle_resume_and_unlock when used externally.
199 void cpuidle_disable_device(struct cpuidle_device
*dev
)
203 if (!cpuidle_curr_driver
|| !cpuidle_curr_governor
)
208 if (cpuidle_curr_governor
->disable
)
209 cpuidle_curr_governor
->disable(dev
);
211 cpuidle_remove_state_sysfs(dev
);
215 EXPORT_SYMBOL_GPL(cpuidle_disable_device
);
217 #ifdef CONFIG_ARCH_HAS_CPU_RELAX
218 static int poll_idle(struct cpuidle_device
*dev
, struct cpuidle_state
*st
)
226 while (!need_resched())
230 diff
= ktime_to_us(ktime_sub(t2
, t1
));
238 static void poll_idle_init(struct cpuidle_device
*dev
)
240 struct cpuidle_state
*state
= &dev
->states
[0];
242 cpuidle_set_statedata(state
, NULL
);
244 snprintf(state
->name
, CPUIDLE_NAME_LEN
, "C0");
245 snprintf(state
->desc
, CPUIDLE_DESC_LEN
, "CPUIDLE CORE POLL IDLE");
246 state
->exit_latency
= 0;
247 state
->target_residency
= 0;
248 state
->power_usage
= -1;
249 state
->flags
= CPUIDLE_FLAG_POLL
;
250 state
->enter
= poll_idle
;
253 static void poll_idle_init(struct cpuidle_device
*dev
) {}
254 #endif /* CONFIG_ARCH_HAS_CPU_RELAX */
257 * __cpuidle_register_device - internal register function called before register
258 * and enable routines
261 * cpuidle_lock mutex must be held before this is called
263 static int __cpuidle_register_device(struct cpuidle_device
*dev
)
266 struct sys_device
*sys_dev
= get_cpu_sysdev((unsigned long)dev
->cpu
);
270 if (!try_module_get(cpuidle_curr_driver
->owner
))
273 init_completion(&dev
->kobj_unregister
);
277 per_cpu(cpuidle_devices
, dev
->cpu
) = dev
;
278 list_add(&dev
->device_list
, &cpuidle_detected_devices
);
279 if ((ret
= cpuidle_add_sysfs(sys_dev
))) {
280 module_put(cpuidle_curr_driver
->owner
);
289 * cpuidle_register_device - registers a CPU's idle PM feature
292 int cpuidle_register_device(struct cpuidle_device
*dev
)
296 mutex_lock(&cpuidle_lock
);
298 if ((ret
= __cpuidle_register_device(dev
))) {
299 mutex_unlock(&cpuidle_lock
);
303 cpuidle_enable_device(dev
);
304 cpuidle_install_idle_handler();
306 mutex_unlock(&cpuidle_lock
);
312 EXPORT_SYMBOL_GPL(cpuidle_register_device
);
315 * cpuidle_unregister_device - unregisters a CPU's idle PM feature
318 void cpuidle_unregister_device(struct cpuidle_device
*dev
)
320 struct sys_device
*sys_dev
= get_cpu_sysdev((unsigned long)dev
->cpu
);
322 if (dev
->registered
== 0)
325 cpuidle_pause_and_lock();
327 cpuidle_disable_device(dev
);
329 cpuidle_remove_sysfs(sys_dev
);
330 list_del(&dev
->device_list
);
331 wait_for_completion(&dev
->kobj_unregister
);
332 per_cpu(cpuidle_devices
, dev
->cpu
) = NULL
;
334 cpuidle_resume_and_unlock();
336 module_put(cpuidle_curr_driver
->owner
);
339 EXPORT_SYMBOL_GPL(cpuidle_unregister_device
);
343 static void smp_callback(void *v
)
345 /* we already woke the CPU up, nothing more to do */
349 * This function gets called when a part of the kernel has a new latency
350 * requirement. This means we need to get all processors out of their C-state,
351 * and then recalculate a new suitable C-state. Just do a cross-cpu IPI; that
352 * wakes them all right up.
354 static int cpuidle_latency_notify(struct notifier_block
*b
,
355 unsigned long l
, void *v
)
357 smp_call_function(smp_callback
, NULL
, 1);
361 static struct notifier_block cpuidle_latency_notifier
= {
362 .notifier_call
= cpuidle_latency_notify
,
365 static inline void latency_notifier_init(struct notifier_block
*n
)
367 pm_qos_add_notifier(PM_QOS_CPU_DMA_LATENCY
, n
);
370 #else /* CONFIG_SMP */
372 #define latency_notifier_init(x) do { } while (0)
374 #endif /* CONFIG_SMP */
377 * cpuidle_init - core initializer
379 static int __init
cpuidle_init(void)
383 pm_idle_old
= pm_idle
;
385 ret
= cpuidle_add_class_sysfs(&cpu_sysdev_class
);
389 latency_notifier_init(&cpuidle_latency_notifier
);
394 core_initcall(cpuidle_init
);