[deliverable/linux.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.h>
#include <linux/cpu.h>
#include <linux/cpuidle.h>
#include <linux/ktime.h>
#include <linux/hrtimer.h>
#include <linux/module.h>
#include <trace/events/power.h>

#include "cpuidle.h"

DEFINE_PER_CPU(struct cpuidle_device *, cpuidle_devices);

DEFINE_MUTEX(cpuidle_lock);
LIST_HEAD(cpuidle_detected_devices);

static int enabled_devices;
static int off __read_mostly;
static int initialized __read_mostly;

int cpuidle_disabled(void)
{
	return off;
}
void disable_cpuidle(void)
{
	off = 1;
}

#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
 * return non-zero on failure
 */
int cpuidle_idle_call(void)
{
	struct cpuidle_device *dev = __this_cpu_read(cpuidle_devices);
	struct cpuidle_driver *drv = cpuidle_get_driver();
	struct cpuidle_state *target_state;
	int next_state, entered_state;

	if (off)
		return -ENODEV;

	if (!initialized)
		return -ENODEV;

	/* check if the device is ready */
	if (!dev || !dev->enabled)
		return -EBUSY;

#if 0
	/* shows regressions, re-enable for 2.6.29 */
	/*
	 * run any timers that can be run now, at this point
	 * before calculating the idle duration etc.
	 */
	hrtimer_peek_ahead_timers();
#endif

	/* ask the governor for the next state */
	next_state = cpuidle_curr_governor->select(drv, dev);
	if (need_resched()) {
		local_irq_enable();
		return 0;
	}

	target_state = &drv->states[next_state];

	trace_power_start(POWER_CSTATE, next_state, dev->cpu);
	trace_cpu_idle(next_state, dev->cpu);

	entered_state = target_state->enter(dev, drv, next_state);

	trace_power_end(dev->cpu);
	trace_cpu_idle(PWR_EVENT_EXIT, dev->cpu);

	if (entered_state >= 0) {
		/* Update cpuidle counters */
		/* This can be moved to within driver enter routine
		 * but that results in multiple copies of same code.
		 */
		dev->states_usage[entered_state].time +=
				(unsigned long long)dev->last_residency;
		dev->states_usage[entered_state].usage++;
	}

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

	return 0;
}

/**
 * cpuidle_install_idle_handler - installs the cpuidle idle loop handler
 */
void cpuidle_install_idle_handler(void)
{
	if (enabled_devices) {
		/* Make sure all changes finished before we switch to new idle */
		smp_wmb();
		initialized = 1;
	}
}

/**
 * cpuidle_uninstall_idle_handler - uninstalls the cpuidle idle loop handler
 */
void cpuidle_uninstall_idle_handler(void)
{
	if (enabled_devices) {
		initialized = 0;
		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);

#ifdef CONFIG_ARCH_HAS_CPU_RELAX
static int poll_idle(struct cpuidle_device *dev,
		struct cpuidle_driver *drv, int index)
{
	ktime_t	t1, t2;
	s64 diff;

	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;

	dev->last_residency = (int) diff;

	return index;
}

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

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

/**
 * 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_get_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;
	}

	poll_idle_init(cpuidle_get_driver());

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

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

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

	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_get_driver() || !cpuidle_curr_governor)
		return;

	dev->enabled = 0;

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

	cpuidle_remove_state_sysfs(dev);
	enabled_devices--;
}

EXPORT_SYMBOL_GPL(cpuidle_disable_device);

/**
 * __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 device *cpu_dev = get_cpu_device((unsigned long)dev->cpu);
	struct cpuidle_driver *cpuidle_driver = cpuidle_get_driver();

	if (!dev)
		return -EINVAL;
	if (!try_module_get(cpuidle_driver->owner))
		return -EINVAL;

	init_completion(&dev->kobj_unregister);

	per_cpu(cpuidle_devices, dev->cpu) = dev;
	list_add(&dev->device_list, &cpuidle_detected_devices);
	if ((ret = cpuidle_add_sysfs(cpu_dev))) {
		module_put(cpuidle_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 device *cpu_dev = get_cpu_device((unsigned long)dev->cpu);
	struct cpuidle_driver *cpuidle_driver = cpuidle_get_driver();

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

	cpuidle_pause_and_lock();

	cpuidle_disable_device(dev);

	cpuidle_remove_sysfs(cpu_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_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;

	if (cpuidle_disabled())
		return -ENODEV;

	ret = cpuidle_add_interface(cpu_subsys.dev_root);
	if (ret)
		return ret;

	latency_notifier_init(&cpuidle_latency_notifier);

	return 0;
}

module_param(off, int, 0444);
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>
e8db0be1	15	#include <linux/pm_qos.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>
884b17e1	20	#include <linux/module.h>
288f023e	21	#include <trace/events/power.h>
4f86d3a8 LB	22
	23	#include "cpuidle.h"
	24
	25	DEFINE_PER_CPU(struct cpuidle_device *, cpuidle_devices);
4f86d3a8 LB	26
	27	DEFINE_MUTEX(cpuidle_lock);
	28	LIST_HEAD(cpuidle_detected_devices);
4f86d3a8 LB	29
4f86d3a8 LB	30	static int enabled_devices;
62027aea	31	static int off __read_mostly;
a0bfa137	32	static int initialized __read_mostly;
62027aea LB	33
	34	int cpuidle_disabled(void)
	35	{
	36	return off;
	37	}
d91ee586 LB	38	void disable_cpuidle(void)
	39	{
	40	off = 1;
	41	}
4f86d3a8	42
a6869cc4 VP	43	#if defined(CONFIG_ARCH_HAS_CPU_IDLE_WAIT)
	44	static void cpuidle_kick_cpus(void)
	45	{
	46	cpu_idle_wait();
	47	}
	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) {}
	52	#endif
	53
dcb84f33 VP	54	static int __cpuidle_register_device(struct cpuidle_device *dev);
dcb84f33 VP	55
4f86d3a8 LB	56	/**
	57	* cpuidle_idle_call - the main idle loop
	58	*
	59	* NOTE: no locks or semaphores should be used here
a0bfa137	60	* return non-zero on failure
4f86d3a8	61	*/
a0bfa137	62	int cpuidle_idle_call(void)
4f86d3a8	63	{
4a6f4fe8	64	struct cpuidle_device *dev = __this_cpu_read(cpuidle_devices);
46bcfad7	65	struct cpuidle_driver *drv = cpuidle_get_driver();
4f86d3a8	66	struct cpuidle_state *target_state;
e978aa7d	67	int next_state, entered_state;
4f86d3a8	68
a0bfa137 LB	69	if (off)
	70	return -ENODEV;
	71
	72	if (!initialized)
	73	return -ENODEV;
	74
4f86d3a8	75	/* check if the device is ready */
a0bfa137 LB	76	if (!dev \|\| !dev->enabled)
a0bfa137 LB	77	return -EBUSY;
4f86d3a8	78
9a655837 AV	79	#if 0
9a655837 AV	80	/* shows regressions, re-enable for 2.6.29 */
2e94d1f7 AV	81	/*
	82	* run any timers that can be run now, at this point
	83	* before calculating the idle duration etc.
	84	*/
	85	hrtimer_peek_ahead_timers();
9a655837	86	#endif
71abbbf8	87
4f86d3a8	88	/* ask the governor for the next state */
46bcfad7	89	next_state = cpuidle_curr_governor->select(drv, dev);
246eb7f0 KH	90	if (need_resched()) {
246eb7f0 KH	91	local_irq_enable();
a0bfa137	92	return 0;
246eb7f0 KH	93	}
246eb7f0 KH	94
46bcfad7	95	target_state = &drv->states[next_state];
f77cfe4e TR	96
	97	trace_power_start(POWER_CSTATE, next_state, dev->cpu);
	98	trace_cpu_idle(next_state, dev->cpu);
	99
46bcfad7	100	entered_state = target_state->enter(dev, drv, next_state);
f77cfe4e TR	101
	102	trace_power_end(dev->cpu);
	103	trace_cpu_idle(PWR_EVENT_EXIT, dev->cpu);
	104
e978aa7d DD	105	if (entered_state >= 0) {
	106	/* Update cpuidle counters */
	107	/* This can be moved to within driver enter routine
	108	* but that results in multiple copies of same code.
	109	*/
4202735e	110	dev->states_usage[entered_state].time +=
e978aa7d	111	(unsigned long long)dev->last_residency;
4202735e	112	dev->states_usage[entered_state].usage++;
e978aa7d	113	}
4f86d3a8 LB	114
	115	/* give the governor an opportunity to reflect on the outcome */
	116	if (cpuidle_curr_governor->reflect)
e978aa7d	117	cpuidle_curr_governor->reflect(dev, entered_state);
a0bfa137 LB	118
a0bfa137 LB	119	return 0;
4f86d3a8 LB	120	}
	121
	122	/**
	123	* cpuidle_install_idle_handler - installs the cpuidle idle loop handler
	124	*/
	125	void cpuidle_install_idle_handler(void)
	126	{
a0bfa137	127	if (enabled_devices) {
4f86d3a8 LB	128	/* Make sure all changes finished before we switch to new idle */
4f86d3a8 LB	129	smp_wmb();
a0bfa137	130	initialized = 1;
4f86d3a8 LB	131	}
	132	}
	133
	134	/**
	135	* cpuidle_uninstall_idle_handler - uninstalls the cpuidle idle loop handler
	136	*/
	137	void cpuidle_uninstall_idle_handler(void)
	138	{
a0bfa137 LB	139	if (enabled_devices) {
a0bfa137 LB	140	initialized = 0;
a6869cc4	141	cpuidle_kick_cpus();
4f86d3a8 LB	142	}
	143	}
	144
	145	/**
	146	* cpuidle_pause_and_lock - temporarily disables CPUIDLE
	147	*/
	148	void cpuidle_pause_and_lock(void)
	149	{
	150	mutex_lock(&cpuidle_lock);
	151	cpuidle_uninstall_idle_handler();
	152	}
	153
	154	EXPORT_SYMBOL_GPL(cpuidle_pause_and_lock);
	155
	156	/**
	157	* cpuidle_resume_and_unlock - resumes CPUIDLE operation
	158	*/
	159	void cpuidle_resume_and_unlock(void)
	160	{
	161	cpuidle_install_idle_handler();
	162	mutex_unlock(&cpuidle_lock);
	163	}
	164
	165	EXPORT_SYMBOL_GPL(cpuidle_resume_and_unlock);
	166
d8c216cf	167	#ifdef CONFIG_ARCH_HAS_CPU_RELAX
46bcfad7 DD	168	static int poll_idle(struct cpuidle_device *dev,
46bcfad7 DD	169	struct cpuidle_driver *drv, int index)
d8c216cf RW	170	{
	171	ktime_t t1, t2;
	172	s64 diff;
d8c216cf RW	173
	174	t1 = ktime_get();
	175	local_irq_enable();
	176	while (!need_resched())
	177	cpu_relax();
	178
	179	t2 = ktime_get();
	180	diff = ktime_to_us(ktime_sub(t2, t1));
	181	if (diff > INT_MAX)
	182	diff = INT_MAX;
	183
e978aa7d DD	184	dev->last_residency = (int) diff;
	185
	186	return index;
d8c216cf RW	187	}
d8c216cf RW	188
46bcfad7	189	static void poll_idle_init(struct cpuidle_driver *drv)
d8c216cf	190	{
46bcfad7	191	struct cpuidle_state *state = &drv->states[0];
d8c216cf	192
720f1c30	193	snprintf(state->name, CPUIDLE_NAME_LEN, "POLL");
d8c216cf RW	194	snprintf(state->desc, CPUIDLE_DESC_LEN, "CPUIDLE CORE POLL IDLE");
	195	state->exit_latency = 0;
	196	state->target_residency = 0;
	197	state->power_usage = -1;
d247632c	198	state->flags = 0;
d8c216cf RW	199	state->enter = poll_idle;
	200	}
	201	#else
46bcfad7	202	static void poll_idle_init(struct cpuidle_driver *drv) {}
d8c216cf RW	203	#endif /* CONFIG_ARCH_HAS_CPU_RELAX */
d8c216cf RW	204
4f86d3a8 LB	205	/**
	206	* cpuidle_enable_device - enables idle PM for a CPU
	207	* @dev: the CPU
	208	*
	209	* This function must be called between cpuidle_pause_and_lock and
	210	* cpuidle_resume_and_unlock when used externally.
	211	*/
	212	int cpuidle_enable_device(struct cpuidle_device *dev)
	213	{
	214	int ret, i;
	215
	216	if (dev->enabled)
	217	return 0;
752138df	218	if (!cpuidle_get_driver() \|\| !cpuidle_curr_governor)
4f86d3a8 LB	219	return -EIO;
	220	if (!dev->state_count)
	221	return -EINVAL;
	222
dcb84f33 VP	223	if (dev->registered == 0) {
	224	ret = __cpuidle_register_device(dev);
	225	if (ret)
	226	return ret;
	227	}
	228
46bcfad7	229	poll_idle_init(cpuidle_get_driver());
d8c216cf	230
4f86d3a8 LB	231	if ((ret = cpuidle_add_state_sysfs(dev)))
	232	return ret;
	233
	234	if (cpuidle_curr_governor->enable &&
46bcfad7	235	(ret = cpuidle_curr_governor->enable(cpuidle_get_driver(), dev)))
4f86d3a8 LB	236	goto fail_sysfs;
	237
	238	for (i = 0; i < dev->state_count; i++) {
4202735e DD	239	dev->states_usage[i].usage = 0;
4202735e DD	240	dev->states_usage[i].time = 0;
4f86d3a8 LB	241	}
4f86d3a8 LB	242	dev->last_residency = 0;
4f86d3a8 LB	243
	244	smp_wmb();
	245
	246	dev->enabled = 1;
	247
	248	enabled_devices++;
	249	return 0;
	250
	251	fail_sysfs:
	252	cpuidle_remove_state_sysfs(dev);
	253
	254	return ret;
	255	}
	256
	257	EXPORT_SYMBOL_GPL(cpuidle_enable_device);
	258
	259	/**
	260	* cpuidle_disable_device - disables idle PM for a CPU
	261	* @dev: the CPU
	262	*
	263	* This function must be called between cpuidle_pause_and_lock and
	264	* cpuidle_resume_and_unlock when used externally.
	265	*/
	266	void cpuidle_disable_device(struct cpuidle_device *dev)
	267	{
	268	if (!dev->enabled)
	269	return;
752138df	270	if (!cpuidle_get_driver() \|\| !cpuidle_curr_governor)
4f86d3a8 LB	271	return;
	272
	273	dev->enabled = 0;
	274
	275	if (cpuidle_curr_governor->disable)
46bcfad7	276	cpuidle_curr_governor->disable(cpuidle_get_driver(), dev);
4f86d3a8 LB	277
	278	cpuidle_remove_state_sysfs(dev);
	279	enabled_devices--;
	280	}
	281
	282	EXPORT_SYMBOL_GPL(cpuidle_disable_device);
	283
	284	/**
dcb84f33 VP	285	* __cpuidle_register_device - internal register function called before register
dcb84f33 VP	286	* and enable routines
4f86d3a8	287	* @dev: the cpu
dcb84f33 VP	288	*
dcb84f33 VP	289	* cpuidle_lock mutex must be held before this is called
4f86d3a8	290	*/
dcb84f33	291	static int __cpuidle_register_device(struct cpuidle_device *dev)
4f86d3a8 LB	292	{
4f86d3a8 LB	293	int ret;
8a25a2fd	294	struct device *cpu_dev = get_cpu_device((unsigned long)dev->cpu);
752138df	295	struct cpuidle_driver *cpuidle_driver = cpuidle_get_driver();
4f86d3a8	296
8a25a2fd	297	if (!dev)
4f86d3a8	298	return -EINVAL;
752138df	299	if (!try_module_get(cpuidle_driver->owner))
4f86d3a8 LB	300	return -EINVAL;
	301
	302	init_completion(&dev->kobj_unregister);
	303
4f86d3a8 LB	304	per_cpu(cpuidle_devices, dev->cpu) = dev;
4f86d3a8 LB	305	list_add(&dev->device_list, &cpuidle_detected_devices);
8a25a2fd	306	if ((ret = cpuidle_add_sysfs(cpu_dev))) {
752138df	307	module_put(cpuidle_driver->owner);
4f86d3a8 LB	308	return ret;
	309	}
	310
dcb84f33 VP	311	dev->registered = 1;
	312	return 0;
	313	}
	314
	315	/**
	316	* cpuidle_register_device - registers a CPU's idle PM feature
	317	* @dev: the cpu
	318	*/
	319	int cpuidle_register_device(struct cpuidle_device *dev)
	320	{
	321	int ret;
	322
	323	mutex_lock(&cpuidle_lock);
	324
	325	if ((ret = __cpuidle_register_device(dev))) {
	326	mutex_unlock(&cpuidle_lock);
	327	return ret;
	328	}
	329
4f86d3a8 LB	330	cpuidle_enable_device(dev);
	331	cpuidle_install_idle_handler();
	332
	333	mutex_unlock(&cpuidle_lock);
	334
	335	return 0;
	336
	337	}
	338
	339	EXPORT_SYMBOL_GPL(cpuidle_register_device);
	340
	341	/**
	342	* cpuidle_unregister_device - unregisters a CPU's idle PM feature
	343	* @dev: the cpu
	344	*/
	345	void cpuidle_unregister_device(struct cpuidle_device *dev)
	346	{
8a25a2fd	347	struct device *cpu_dev = get_cpu_device((unsigned long)dev->cpu);
752138df	348	struct cpuidle_driver *cpuidle_driver = cpuidle_get_driver();
4f86d3a8	349
dcb84f33 VP	350	if (dev->registered == 0)
	351	return;
	352
4f86d3a8 LB	353	cpuidle_pause_and_lock();
	354
	355	cpuidle_disable_device(dev);
	356
8a25a2fd	357	cpuidle_remove_sysfs(cpu_dev);
4f86d3a8 LB	358	list_del(&dev->device_list);
	359	wait_for_completion(&dev->kobj_unregister);
	360	per_cpu(cpuidle_devices, dev->cpu) = NULL;
	361
	362	cpuidle_resume_and_unlock();
	363
752138df	364	module_put(cpuidle_driver->owner);
4f86d3a8 LB	365	}
	366
	367	EXPORT_SYMBOL_GPL(cpuidle_unregister_device);
	368
	369	#ifdef CONFIG_SMP
	370
	371	static void smp_callback(void *v)
	372	{
	373	/* we already woke the CPU up, nothing more to do */
	374	}
	375
	376	/*
	377	* This function gets called when a part of the kernel has a new latency
	378	* requirement. This means we need to get all processors out of their C-state,
	379	* and then recalculate a new suitable C-state. Just do a cross-cpu IPI; that
	380	* wakes them all right up.
	381	*/
	382	static int cpuidle_latency_notify(struct notifier_block *b,
	383	unsigned long l, void *v)
	384	{
8691e5a8	385	smp_call_function(smp_callback, NULL, 1);
4f86d3a8 LB	386	return NOTIFY_OK;
	387	}
	388
	389	static struct notifier_block cpuidle_latency_notifier = {
	390	.notifier_call = cpuidle_latency_notify,
	391	};
	392
d82b3518 MG	393	static inline void latency_notifier_init(struct notifier_block *n)
	394	{
	395	pm_qos_add_notifier(PM_QOS_CPU_DMA_LATENCY, n);
	396	}
4f86d3a8 LB	397
	398	#else /* CONFIG_SMP */
	399
	400	#define latency_notifier_init(x) do { } while (0)
	401
	402	#endif /* CONFIG_SMP */
	403
	404	/**
	405	* cpuidle_init - core initializer
	406	*/
	407	static int __init cpuidle_init(void)
	408	{
	409	int ret;
	410
62027aea LB	411	if (cpuidle_disabled())
	412	return -ENODEV;
	413
8a25a2fd	414	ret = cpuidle_add_interface(cpu_subsys.dev_root);
4f86d3a8 LB	415	if (ret)
	416	return ret;
	417
	418	latency_notifier_init(&cpuidle_latency_notifier);
	419
	420	return 0;
	421	}
	422
62027aea	423	module_param(off, int, 0444);
4f86d3a8	424	core_initcall(cpuidle_init);