[mirror_ubuntu-jammy-kernel.git] / drivers / cpuidle / cpuidle.c

/*
 * cpuidle.c - core cpuidle infrastructure
 *
 * (C) 2006-2007 Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>
 *               Shaohua Li <shaohua.li@intel.com>
 *               Adam Belay <abelay@novell.com>
 *
 * This code is licenced under the GPL.
 */

#include <linux/kernel.h>
#include <linux/mutex.h>
#include <linux/sched.h>
#include <linux/notifier.h>
#include <linux/pm_qos_params.h>
#include <linux/cpu.h>
#include <linux/cpuidle.h>
#include <linux/ktime.h>
#include <linux/hrtimer.h>

#include "cpuidle.h"

DEFINE_PER_CPU(struct cpuidle_device *, cpuidle_devices);

DEFINE_MUTEX(cpuidle_lock);
LIST_HEAD(cpuidle_detected_devices);
static void (*pm_idle_old)(void);

static int enabled_devices;

#if defined(CONFIG_ARCH_HAS_CPU_IDLE_WAIT)
static void cpuidle_kick_cpus(void)
{
	cpu_idle_wait();
}
#elif defined(CONFIG_SMP)
# error "Arch needs cpu_idle_wait() equivalent here"
#else /* !CONFIG_ARCH_HAS_CPU_IDLE_WAIT && !CONFIG_SMP */
static void cpuidle_kick_cpus(void) {}
#endif

static int __cpuidle_register_device(struct cpuidle_device *dev);

/**
 * cpuidle_idle_call - the main idle loop
 *
 * NOTE: no locks or semaphores should be used here
 */
static void cpuidle_idle_call(void)
{
	struct cpuidle_device *dev = __get_cpu_var(cpuidle_devices);
	struct cpuidle_state *target_state;
	int next_state;

	/* check if the device is ready */
	if (!dev || !dev->enabled) {
		if (pm_idle_old)
			pm_idle_old();
		else
#if defined(CONFIG_ARCH_HAS_DEFAULT_IDLE)
			default_idle();
#else
			local_irq_enable();
#endif
		return;
	}

	/*
	 * run any timers that can be run now, at this point
	 * before calculating the idle duration etc.
	 */
	hrtimer_peek_ahead_timers();

	/* ask the governor for the next state */
	next_state = cpuidle_curr_governor->select(dev);
	if (need_resched())
		return;
	target_state = &dev->states[next_state];

	/* enter the state and update stats */
	dev->last_state = target_state;
	dev->last_residency = target_state->enter(dev, target_state);
	if (dev->last_state)
		target_state = dev->last_state;

	target_state->time += (unsigned long long)dev->last_residency;
	target_state->usage++;

	/* give the governor an opportunity to reflect on the outcome */
	if (cpuidle_curr_governor->reflect)
		cpuidle_curr_governor->reflect(dev);
}

/**
 * cpuidle_install_idle_handler - installs the cpuidle idle loop handler
 */
void cpuidle_install_idle_handler(void)
{
	if (enabled_devices && (pm_idle != cpuidle_idle_call)) {
		/* Make sure all changes finished before we switch to new idle */
		smp_wmb();
		pm_idle = cpuidle_idle_call;
	}
}

/**
 * cpuidle_uninstall_idle_handler - uninstalls the cpuidle idle loop handler
 */
void cpuidle_uninstall_idle_handler(void)
{
	if (enabled_devices && pm_idle_old && (pm_idle != pm_idle_old)) {
		pm_idle = pm_idle_old;
		cpuidle_kick_cpus();
	}
}

/**
 * cpuidle_pause_and_lock - temporarily disables CPUIDLE
 */
void cpuidle_pause_and_lock(void)
{
	mutex_lock(&cpuidle_lock);
	cpuidle_uninstall_idle_handler();
}

EXPORT_SYMBOL_GPL(cpuidle_pause_and_lock);

/**
 * cpuidle_resume_and_unlock - resumes CPUIDLE operation
 */
void cpuidle_resume_and_unlock(void)
{
	cpuidle_install_idle_handler();
	mutex_unlock(&cpuidle_lock);
}

EXPORT_SYMBOL_GPL(cpuidle_resume_and_unlock);

/**
 * cpuidle_enable_device - enables idle PM for a CPU
 * @dev: the CPU
 *
 * This function must be called between cpuidle_pause_and_lock and
 * cpuidle_resume_and_unlock when used externally.
 */
int cpuidle_enable_device(struct cpuidle_device *dev)
{
	int ret, i;

	if (dev->enabled)
		return 0;
	if (!cpuidle_curr_driver || !cpuidle_curr_governor)
		return -EIO;
	if (!dev->state_count)
		return -EINVAL;

	if (dev->registered == 0) {
		ret = __cpuidle_register_device(dev);
		if (ret)
			return ret;
	}

	if ((ret = cpuidle_add_state_sysfs(dev)))
		return ret;

	if (cpuidle_curr_governor->enable &&
	    (ret = cpuidle_curr_governor->enable(dev)))
		goto fail_sysfs;

	for (i = 0; i < dev->state_count; i++) {
		dev->states[i].usage = 0;
		dev->states[i].time = 0;
	}
	dev->last_residency = 0;
	dev->last_state = NULL;

	smp_wmb();

	dev->enabled = 1;

	enabled_devices++;
	return 0;

fail_sysfs:
	cpuidle_remove_state_sysfs(dev);

	return ret;
}

EXPORT_SYMBOL_GPL(cpuidle_enable_device);

/**
 * cpuidle_disable_device - disables idle PM for a CPU
 * @dev: the CPU
 *
 * This function must be called between cpuidle_pause_and_lock and
 * cpuidle_resume_and_unlock when used externally.
 */
void cpuidle_disable_device(struct cpuidle_device *dev)
{
	if (!dev->enabled)
		return;
	if (!cpuidle_curr_driver || !cpuidle_curr_governor)
		return;

	dev->enabled = 0;

	if (cpuidle_curr_governor->disable)
		cpuidle_curr_governor->disable(dev);

	cpuidle_remove_state_sysfs(dev);
	enabled_devices--;
}

EXPORT_SYMBOL_GPL(cpuidle_disable_device);

#ifdef CONFIG_ARCH_HAS_CPU_RELAX
static int poll_idle(struct cpuidle_device *dev, struct cpuidle_state *st)
{
	ktime_t	t1, t2;
	s64 diff;
	int ret;

	t1 = ktime_get();
	local_irq_enable();
	while (!need_resched())
		cpu_relax();

	t2 = ktime_get();
	diff = ktime_to_us(ktime_sub(t2, t1));
	if (diff > INT_MAX)
		diff = INT_MAX;

	ret = (int) diff;
	return ret;
}

static void poll_idle_init(struct cpuidle_device *dev)
{
	struct cpuidle_state *state = &dev->states[0];

	cpuidle_set_statedata(state, NULL);

	snprintf(state->name, CPUIDLE_NAME_LEN, "C0");
	snprintf(state->desc, CPUIDLE_DESC_LEN, "CPUIDLE CORE POLL IDLE");
	state->exit_latency = 0;
	state->target_residency = 0;
	state->power_usage = -1;
	state->flags = CPUIDLE_FLAG_POLL;
	state->enter = poll_idle;
}
#else
static void poll_idle_init(struct cpuidle_device *dev) {}
#endif /* CONFIG_ARCH_HAS_CPU_RELAX */

/**
 * __cpuidle_register_device - internal register function called before register
 * and enable routines
 * @dev: the cpu
 *
 * cpuidle_lock mutex must be held before this is called
 */
static int __cpuidle_register_device(struct cpuidle_device *dev)
{
	int ret;
	struct sys_device *sys_dev = get_cpu_sysdev((unsigned long)dev->cpu);

	if (!sys_dev)
		return -EINVAL;
	if (!try_module_get(cpuidle_curr_driver->owner))
		return -EINVAL;

	init_completion(&dev->kobj_unregister);

	poll_idle_init(dev);

	per_cpu(cpuidle_devices, dev->cpu) = dev;
	list_add(&dev->device_list, &cpuidle_detected_devices);
	if ((ret = cpuidle_add_sysfs(sys_dev))) {
		module_put(cpuidle_curr_driver->owner);
		return ret;
	}

	dev->registered = 1;
	return 0;
}

/**
 * cpuidle_register_device - registers a CPU's idle PM feature
 * @dev: the cpu
 */
int cpuidle_register_device(struct cpuidle_device *dev)
{
	int ret;

	mutex_lock(&cpuidle_lock);

	if ((ret = __cpuidle_register_device(dev))) {
		mutex_unlock(&cpuidle_lock);
		return ret;
	}

	cpuidle_enable_device(dev);
	cpuidle_install_idle_handler();

	mutex_unlock(&cpuidle_lock);

	return 0;

}

EXPORT_SYMBOL_GPL(cpuidle_register_device);

/**
 * cpuidle_unregister_device - unregisters a CPU's idle PM feature
 * @dev: the cpu
 */
void cpuidle_unregister_device(struct cpuidle_device *dev)
{
	struct sys_device *sys_dev = get_cpu_sysdev((unsigned long)dev->cpu);

	if (dev->registered == 0)
		return;

	cpuidle_pause_and_lock();

	cpuidle_disable_device(dev);

	cpuidle_remove_sysfs(sys_dev);
	list_del(&dev->device_list);
	wait_for_completion(&dev->kobj_unregister);
	per_cpu(cpuidle_devices, dev->cpu) = NULL;

	cpuidle_resume_and_unlock();

	module_put(cpuidle_curr_driver->owner);
}

EXPORT_SYMBOL_GPL(cpuidle_unregister_device);

#ifdef CONFIG_SMP

static void smp_callback(void *v)
{
	/* we already woke the CPU up, nothing more to do */
}

/*
 * This function gets called when a part of the kernel has a new latency
 * requirement.  This means we need to get all processors out of their C-state,
 * and then recalculate a new suitable C-state. Just do a cross-cpu IPI; that
 * wakes them all right up.
 */
static int cpuidle_latency_notify(struct notifier_block *b,
		unsigned long l, void *v)
{
	smp_call_function(smp_callback, NULL, 1);
	return NOTIFY_OK;
}

static struct notifier_block cpuidle_latency_notifier = {
	.notifier_call = cpuidle_latency_notify,
};

static inline void latency_notifier_init(struct notifier_block *n)
{
	pm_qos_add_notifier(PM_QOS_CPU_DMA_LATENCY, n);
}

#else /* CONFIG_SMP */

#define latency_notifier_init(x) do { } while (0)

#endif /* CONFIG_SMP */

/**
 * cpuidle_init - core initializer
 */
static int __init cpuidle_init(void)
{
	int ret;

	pm_idle_old = pm_idle;

	ret = cpuidle_add_class_sysfs(&cpu_sysdev_class);
	if (ret)
		return ret;

	latency_notifier_init(&cpuidle_latency_notifier);

	return 0;
}

core_initcall(cpuidle_init);
Commit	Line	Data
4f86d3a8 LB	1	/*
	2	* cpuidle.c - core cpuidle infrastructure
	3	*
	4	* (C) 2006-2007 Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>
	5	* Shaohua Li <shaohua.li@intel.com>
	6	* Adam Belay <abelay@novell.com>
	7	*
	8	* This code is licenced under the GPL.
	9	*/
	10
	11	#include <linux/kernel.h>
	12	#include <linux/mutex.h>
	13	#include <linux/sched.h>
	14	#include <linux/notifier.h>
d82b3518	15	#include <linux/pm_qos_params.h>
4f86d3a8 LB	16	#include <linux/cpu.h>
4f86d3a8 LB	17	#include <linux/cpuidle.h>
9a0b8415	18	#include <linux/ktime.h>
2e94d1f7	19	#include <linux/hrtimer.h>
4f86d3a8 LB	20
	21	#include "cpuidle.h"
	22
	23	DEFINE_PER_CPU(struct cpuidle_device *, cpuidle_devices);
4f86d3a8 LB	24
	25	DEFINE_MUTEX(cpuidle_lock);
	26	LIST_HEAD(cpuidle_detected_devices);
	27	static void (*pm_idle_old)(void);
	28
	29	static int enabled_devices;
	30
a6869cc4 VP	31	#if defined(CONFIG_ARCH_HAS_CPU_IDLE_WAIT)
	32	static void cpuidle_kick_cpus(void)
	33	{
	34	cpu_idle_wait();
	35	}
	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) {}
	40	#endif
	41
dcb84f33 VP	42	static int __cpuidle_register_device(struct cpuidle_device *dev);
dcb84f33 VP	43
4f86d3a8 LB	44	/**
	45	* cpuidle_idle_call - the main idle loop
	46	*
	47	* NOTE: no locks or semaphores should be used here
	48	*/
	49	static void cpuidle_idle_call(void)
	50	{
	51	struct cpuidle_device *dev = __get_cpu_var(cpuidle_devices);
	52	struct cpuidle_state *target_state;
	53	int next_state;
	54
	55	/* check if the device is ready */
	56	if (!dev \|\| !dev->enabled) {
	57	if (pm_idle_old)
	58	pm_idle_old();
	59	else
89cedfef VP	60	#if defined(CONFIG_ARCH_HAS_DEFAULT_IDLE)
	61	default_idle();
	62	#else
4f86d3a8	63	local_irq_enable();
89cedfef	64	#endif
4f86d3a8 LB	65	return;
	66	}
	67
2e94d1f7 AV	68	/*
	69	* run any timers that can be run now, at this point
	70	* before calculating the idle duration etc.
	71	*/
	72	hrtimer_peek_ahead_timers();
	73
4f86d3a8 LB	74	/* ask the governor for the next state */
	75	next_state = cpuidle_curr_governor->select(dev);
	76	if (need_resched())
	77	return;
	78	target_state = &dev->states[next_state];
	79
	80	/* enter the state and update stats */
4f86d3a8	81	dev->last_state = target_state;
887e301a VP	82	dev->last_residency = target_state->enter(dev, target_state);
	83	if (dev->last_state)
	84	target_state = dev->last_state;
	85
8b78cf60	86	target_state->time += (unsigned long long)dev->last_residency;
4f86d3a8 LB	87	target_state->usage++;
	88
	89	/* give the governor an opportunity to reflect on the outcome */
	90	if (cpuidle_curr_governor->reflect)
	91	cpuidle_curr_governor->reflect(dev);
	92	}
	93
	94	/**
	95	* cpuidle_install_idle_handler - installs the cpuidle idle loop handler
	96	*/
	97	void cpuidle_install_idle_handler(void)
	98	{
	99	if (enabled_devices && (pm_idle != cpuidle_idle_call)) {
	100	/* Make sure all changes finished before we switch to new idle */
	101	smp_wmb();
	102	pm_idle = cpuidle_idle_call;
	103	}
	104	}
	105
	106	/**
	107	* cpuidle_uninstall_idle_handler - uninstalls the cpuidle idle loop handler
	108	*/
	109	void cpuidle_uninstall_idle_handler(void)
	110	{
b032bf70	111	if (enabled_devices && pm_idle_old && (pm_idle != pm_idle_old)) {
4f86d3a8	112	pm_idle = pm_idle_old;
a6869cc4	113	cpuidle_kick_cpus();
4f86d3a8 LB	114	}
	115	}
	116
	117	/**
	118	* cpuidle_pause_and_lock - temporarily disables CPUIDLE
	119	*/
	120	void cpuidle_pause_and_lock(void)
	121	{
	122	mutex_lock(&cpuidle_lock);
	123	cpuidle_uninstall_idle_handler();
	124	}
	125
	126	EXPORT_SYMBOL_GPL(cpuidle_pause_and_lock);
	127
	128	/**
	129	* cpuidle_resume_and_unlock - resumes CPUIDLE operation
	130	*/
	131	void cpuidle_resume_and_unlock(void)
	132	{
	133	cpuidle_install_idle_handler();
	134	mutex_unlock(&cpuidle_lock);
	135	}
	136
	137	EXPORT_SYMBOL_GPL(cpuidle_resume_and_unlock);
	138
	139	/**
	140	* cpuidle_enable_device - enables idle PM for a CPU
	141	* @dev: the CPU
	142	*
	143	* This function must be called between cpuidle_pause_and_lock and
	144	* cpuidle_resume_and_unlock when used externally.
	145	*/
	146	int cpuidle_enable_device(struct cpuidle_device *dev)
	147	{
	148	int ret, i;
	149
	150	if (dev->enabled)
	151	return 0;
	152	if (!cpuidle_curr_driver \|\| !cpuidle_curr_governor)
	153	return -EIO;
	154	if (!dev->state_count)
	155	return -EINVAL;
	156
dcb84f33 VP	157	if (dev->registered == 0) {
	158	ret = __cpuidle_register_device(dev);
	159	if (ret)
	160	return ret;
	161	}
	162
4f86d3a8 LB	163	if ((ret = cpuidle_add_state_sysfs(dev)))
	164	return ret;
	165
	166	if (cpuidle_curr_governor->enable &&
	167	(ret = cpuidle_curr_governor->enable(dev)))
	168	goto fail_sysfs;
	169
	170	for (i = 0; i < dev->state_count; i++) {
	171	dev->states[i].usage = 0;
	172	dev->states[i].time = 0;
	173	}
	174	dev->last_residency = 0;
	175	dev->last_state = NULL;
	176
	177	smp_wmb();
	178
	179	dev->enabled = 1;
	180
	181	enabled_devices++;
	182	return 0;
	183
	184	fail_sysfs:
	185	cpuidle_remove_state_sysfs(dev);
	186
	187	return ret;
	188	}
	189
	190	EXPORT_SYMBOL_GPL(cpuidle_enable_device);
	191
	192	/**
	193	* cpuidle_disable_device - disables idle PM for a CPU
	194	* @dev: the CPU
	195	*
	196	* This function must be called between cpuidle_pause_and_lock and
	197	* cpuidle_resume_and_unlock when used externally.
	198	*/
	199	void cpuidle_disable_device(struct cpuidle_device *dev)
	200	{
	201	if (!dev->enabled)
	202	return;
	203	if (!cpuidle_curr_driver \|\| !cpuidle_curr_governor)
	204	return;
	205
	206	dev->enabled = 0;
	207
	208	if (cpuidle_curr_governor->disable)
	209	cpuidle_curr_governor->disable(dev);
	210
	211	cpuidle_remove_state_sysfs(dev);
	212	enabled_devices--;
	213	}
	214
	215	EXPORT_SYMBOL_GPL(cpuidle_disable_device);
	216
9a0b8415	217	#ifdef CONFIG_ARCH_HAS_CPU_RELAX
	218	static int poll_idle(struct cpuidle_device dev, struct cpuidle_state st)
	219	{
	220	ktime_t t1, t2;
	221	s64 diff;
	222	int ret;
	223
	224	t1 = ktime_get();
	225	local_irq_enable();
	226	while (!need_resched())
	227	cpu_relax();
	228
	229	t2 = ktime_get();
	230	diff = ktime_to_us(ktime_sub(t2, t1));
	231	if (diff > INT_MAX)
	232	diff = INT_MAX;
	233
	234	ret = (int) diff;
	235	return ret;
	236	}
	237
	238	static void poll_idle_init(struct cpuidle_device *dev)
	239	{
	240	struct cpuidle_state *state = &dev->states[0];
	241
	242	cpuidle_set_statedata(state, NULL);
	243
4fcb2fcd VP	244	snprintf(state->name, CPUIDLE_NAME_LEN, "C0");
4fcb2fcd VP	245	snprintf(state->desc, CPUIDLE_DESC_LEN, "CPUIDLE CORE POLL IDLE");
9a0b8415	246	state->exit_latency = 0;
	247	state->target_residency = 0;
	248	state->power_usage = -1;
8e92b660	249	state->flags = CPUIDLE_FLAG_POLL;
9a0b8415	250	state->enter = poll_idle;
	251	}
	252	#else
	253	static void poll_idle_init(struct cpuidle_device *dev) {}
	254	#endif /* CONFIG_ARCH_HAS_CPU_RELAX */
	255
4f86d3a8	256	/**
dcb84f33 VP	257	* __cpuidle_register_device - internal register function called before register
dcb84f33 VP	258	* and enable routines
4f86d3a8	259	* @dev: the cpu
dcb84f33 VP	260	*
dcb84f33 VP	261	* cpuidle_lock mutex must be held before this is called
4f86d3a8	262	*/
dcb84f33	263	static int __cpuidle_register_device(struct cpuidle_device *dev)
4f86d3a8 LB	264	{
	265	int ret;
	266	struct sys_device *sys_dev = get_cpu_sysdev((unsigned long)dev->cpu);
	267
	268	if (!sys_dev)
	269	return -EINVAL;
	270	if (!try_module_get(cpuidle_curr_driver->owner))
	271	return -EINVAL;
	272
	273	init_completion(&dev->kobj_unregister);
	274
9a0b8415	275	poll_idle_init(dev);
9a0b8415	276
4f86d3a8 LB	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))) {
4f86d3a8 LB	280	module_put(cpuidle_curr_driver->owner);
	281	return ret;
	282	}
	283
dcb84f33 VP	284	dev->registered = 1;
	285	return 0;
	286	}
	287
	288	/**
	289	* cpuidle_register_device - registers a CPU's idle PM feature
	290	* @dev: the cpu
	291	*/
	292	int cpuidle_register_device(struct cpuidle_device *dev)
	293	{
	294	int ret;
	295
	296	mutex_lock(&cpuidle_lock);
	297
	298	if ((ret = __cpuidle_register_device(dev))) {
	299	mutex_unlock(&cpuidle_lock);
	300	return ret;
	301	}
	302
4f86d3a8 LB	303	cpuidle_enable_device(dev);
	304	cpuidle_install_idle_handler();
	305
	306	mutex_unlock(&cpuidle_lock);
	307
	308	return 0;
	309
	310	}
	311
	312	EXPORT_SYMBOL_GPL(cpuidle_register_device);
	313
	314	/**
	315	* cpuidle_unregister_device - unregisters a CPU's idle PM feature
	316	* @dev: the cpu
	317	*/
	318	void cpuidle_unregister_device(struct cpuidle_device *dev)
	319	{
	320	struct sys_device *sys_dev = get_cpu_sysdev((unsigned long)dev->cpu);
	321
dcb84f33 VP	322	if (dev->registered == 0)
	323	return;
	324
4f86d3a8 LB	325	cpuidle_pause_and_lock();
	326
	327	cpuidle_disable_device(dev);
	328
	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;
	333
	334	cpuidle_resume_and_unlock();
	335
	336	module_put(cpuidle_curr_driver->owner);
	337	}
	338
	339	EXPORT_SYMBOL_GPL(cpuidle_unregister_device);
	340
	341	#ifdef CONFIG_SMP
	342
	343	static void smp_callback(void *v)
	344	{
	345	/* we already woke the CPU up, nothing more to do */
	346	}
	347
	348	/*
	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.
	353	*/
	354	static int cpuidle_latency_notify(struct notifier_block *b,
	355	unsigned long l, void *v)
	356	{
8691e5a8	357	smp_call_function(smp_callback, NULL, 1);
4f86d3a8 LB	358	return NOTIFY_OK;
	359	}
	360
	361	static struct notifier_block cpuidle_latency_notifier = {
	362	.notifier_call = cpuidle_latency_notify,
	363	};
	364
d82b3518 MG	365	static inline void latency_notifier_init(struct notifier_block *n)
	366	{
	367	pm_qos_add_notifier(PM_QOS_CPU_DMA_LATENCY, n);
	368	}
4f86d3a8 LB	369
	370	#else /* CONFIG_SMP */
	371
	372	#define latency_notifier_init(x) do { } while (0)
	373
	374	#endif /* CONFIG_SMP */
	375
	376	/**
	377	* cpuidle_init - core initializer
	378	*/
	379	static int __init cpuidle_init(void)
	380	{
	381	int ret;
	382
	383	pm_idle_old = pm_idle;
	384
	385	ret = cpuidle_add_class_sysfs(&cpu_sysdev_class);
	386	if (ret)
	387	return ret;
	388
	389	latency_notifier_init(&cpuidle_latency_notifier);
	390
	391	return 0;
	392	}
	393
	394	core_initcall(cpuidle_init);