[mirror_ubuntu-zesty-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 <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_state *target_state;
	int next_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

	/*
	 * Call the device's prepare function before calling the
	 * governor's select function.  ->prepare gives the device's
	 * cpuidle driver a chance to update any dynamic information
	 * of its cpuidle states for the current idle period, e.g.
	 * state availability, latencies, residencies, etc.
	 */
	if (dev->prepare)
		dev->prepare(dev);

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

	target_state = &dev->states[next_state];

	/* enter the state and update stats */
	dev->last_state = target_state;

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

	dev->last_residency = target_state->enter(dev, target_state);

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

	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);

	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_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, "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_device *dev) {}
#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(dev);

	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_get_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);

/**
 * __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);
	struct cpuidle_driver *cpuidle_driver = cpuidle_get_driver();

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

	init_completion(&dev->kobj_unregister);

	/*
	 * cpuidle driver should set the dev->power_specified bit
	 * before registering the device if the driver provides
	 * power_usage numbers.
	 *
	 * For those devices whose ->power_specified is not set,
	 * we fill in power_usage with decreasing values as the
	 * cpuidle code has an implicit assumption that state Cn
	 * uses less power than C(n-1).
	 *
	 * With CONFIG_ARCH_HAS_CPU_RELAX, C0 is already assigned
	 * an power value of -1.  So we use -2, -3, etc, for other
	 * c-states.
	 */
	if (!dev->power_specified) {
		int i;
		for (i = CPUIDLE_DRIVER_STATE_START; i < dev->state_count; i++)
			dev->states[i].power_usage = -1 - i;
	}

	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_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);
	struct cpuidle_driver *cpuidle_driver = cpuidle_get_driver();

	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_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_class_sysfs(&cpu_sysdev_class);
	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>
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>
288f023e	20	#include <trace/events/power.h>
4f86d3a8 LB	21
	22	#include "cpuidle.h"
	23
	24	DEFINE_PER_CPU(struct cpuidle_device *, cpuidle_devices);
4f86d3a8 LB	25
	26	DEFINE_MUTEX(cpuidle_lock);
	27	LIST_HEAD(cpuidle_detected_devices);
4f86d3a8 LB	28
4f86d3a8 LB	29	static int enabled_devices;
62027aea	30	static int off __read_mostly;
a0bfa137	31	static int initialized __read_mostly;
62027aea LB	32
	33	int cpuidle_disabled(void)
	34	{
	35	return off;
	36	}
d91ee586 LB	37	void disable_cpuidle(void)
	38	{
	39	off = 1;
	40	}
4f86d3a8	41
a6869cc4 VP	42	#if defined(CONFIG_ARCH_HAS_CPU_IDLE_WAIT)
	43	static void cpuidle_kick_cpus(void)
	44	{
	45	cpu_idle_wait();
	46	}
	47	#elif defined(CONFIG_SMP)
	48	# error "Arch needs cpu_idle_wait() equivalent here"
	49	#else /* !CONFIG_ARCH_HAS_CPU_IDLE_WAIT && !CONFIG_SMP */
	50	static void cpuidle_kick_cpus(void) {}
	51	#endif
	52
dcb84f33 VP	53	static int __cpuidle_register_device(struct cpuidle_device *dev);
dcb84f33 VP	54
4f86d3a8 LB	55	/**
	56	* cpuidle_idle_call - the main idle loop
	57	*
	58	* NOTE: no locks or semaphores should be used here
a0bfa137	59	* return non-zero on failure
4f86d3a8	60	*/
a0bfa137	61	int cpuidle_idle_call(void)
4f86d3a8	62	{
4a6f4fe8	63	struct cpuidle_device *dev = __this_cpu_read(cpuidle_devices);
4f86d3a8 LB	64	struct cpuidle_state *target_state;
	65	int next_state;
	66
a0bfa137 LB	67	if (off)
	68	return -ENODEV;
	69
	70	if (!initialized)
	71	return -ENODEV;
	72
4f86d3a8	73	/* check if the device is ready */
a0bfa137 LB	74	if (!dev \|\| !dev->enabled)
a0bfa137 LB	75	return -EBUSY;
4f86d3a8	76
9a655837 AV	77	#if 0
9a655837 AV	78	/* shows regressions, re-enable for 2.6.29 */
2e94d1f7 AV	79	/*
	80	* run any timers that can be run now, at this point
	81	* before calculating the idle duration etc.
	82	*/
	83	hrtimer_peek_ahead_timers();
9a655837	84	#endif
71abbbf8 AL	85
	86	/*
	87	* Call the device's prepare function before calling the
	88	* governor's select function. ->prepare gives the device's
	89	* cpuidle driver a chance to update any dynamic information
	90	* of its cpuidle states for the current idle period, e.g.
	91	* state availability, latencies, residencies, etc.
	92	*/
	93	if (dev->prepare)
	94	dev->prepare(dev);
	95
4f86d3a8 LB	96	/* ask the governor for the next state */
4f86d3a8 LB	97	next_state = cpuidle_curr_governor->select(dev);
246eb7f0 KH	98	if (need_resched()) {
246eb7f0 KH	99	local_irq_enable();
a0bfa137	100	return 0;
246eb7f0 KH	101	}
246eb7f0 KH	102
4f86d3a8 LB	103	target_state = &dev->states[next_state];
	104
	105	/* enter the state and update stats */
4f86d3a8	106	dev->last_state = target_state;
f77cfe4e TR	107
	108	trace_power_start(POWER_CSTATE, next_state, dev->cpu);
	109	trace_cpu_idle(next_state, dev->cpu);
	110
887e301a	111	dev->last_residency = target_state->enter(dev, target_state);
f77cfe4e TR	112
	113	trace_power_end(dev->cpu);
	114	trace_cpu_idle(PWR_EVENT_EXIT, dev->cpu);
	115
887e301a VP	116	if (dev->last_state)
	117	target_state = dev->last_state;
	118
8b78cf60	119	target_state->time += (unsigned long long)dev->last_residency;
4f86d3a8 LB	120	target_state->usage++;
	121
	122	/* give the governor an opportunity to reflect on the outcome */
	123	if (cpuidle_curr_governor->reflect)
	124	cpuidle_curr_governor->reflect(dev);
a0bfa137 LB	125
a0bfa137 LB	126	return 0;
4f86d3a8 LB	127	}
	128
	129	/**
	130	* cpuidle_install_idle_handler - installs the cpuidle idle loop handler
	131	*/
	132	void cpuidle_install_idle_handler(void)
	133	{
a0bfa137	134	if (enabled_devices) {
4f86d3a8 LB	135	/* Make sure all changes finished before we switch to new idle */
4f86d3a8 LB	136	smp_wmb();
a0bfa137	137	initialized = 1;
4f86d3a8 LB	138	}
	139	}
	140
	141	/**
	142	* cpuidle_uninstall_idle_handler - uninstalls the cpuidle idle loop handler
	143	*/
	144	void cpuidle_uninstall_idle_handler(void)
	145	{
a0bfa137 LB	146	if (enabled_devices) {
a0bfa137 LB	147	initialized = 0;
a6869cc4	148	cpuidle_kick_cpus();
4f86d3a8 LB	149	}
	150	}
	151
	152	/**
	153	* cpuidle_pause_and_lock - temporarily disables CPUIDLE
	154	*/
	155	void cpuidle_pause_and_lock(void)
	156	{
	157	mutex_lock(&cpuidle_lock);
	158	cpuidle_uninstall_idle_handler();
	159	}
	160
	161	EXPORT_SYMBOL_GPL(cpuidle_pause_and_lock);
	162
	163	/**
	164	* cpuidle_resume_and_unlock - resumes CPUIDLE operation
	165	*/
	166	void cpuidle_resume_and_unlock(void)
	167	{
	168	cpuidle_install_idle_handler();
	169	mutex_unlock(&cpuidle_lock);
	170	}
	171
	172	EXPORT_SYMBOL_GPL(cpuidle_resume_and_unlock);
	173
d8c216cf RW	174	#ifdef CONFIG_ARCH_HAS_CPU_RELAX
	175	static int poll_idle(struct cpuidle_device dev, struct cpuidle_state st)
	176	{
	177	ktime_t t1, t2;
	178	s64 diff;
	179	int ret;
	180
	181	t1 = ktime_get();
	182	local_irq_enable();
	183	while (!need_resched())
	184	cpu_relax();
	185
	186	t2 = ktime_get();
	187	diff = ktime_to_us(ktime_sub(t2, t1));
	188	if (diff > INT_MAX)
	189	diff = INT_MAX;
	190
	191	ret = (int) diff;
	192	return ret;
	193	}
	194
	195	static void poll_idle_init(struct cpuidle_device *dev)
	196	{
	197	struct cpuidle_state *state = &dev->states[0];
	198
	199	cpuidle_set_statedata(state, NULL);
	200
720f1c30	201	snprintf(state->name, CPUIDLE_NAME_LEN, "POLL");
d8c216cf RW	202	snprintf(state->desc, CPUIDLE_DESC_LEN, "CPUIDLE CORE POLL IDLE");
	203	state->exit_latency = 0;
	204	state->target_residency = 0;
	205	state->power_usage = -1;
d247632c	206	state->flags = 0;
d8c216cf RW	207	state->enter = poll_idle;
	208	}
	209	#else
	210	static void poll_idle_init(struct cpuidle_device *dev) {}
	211	#endif /* CONFIG_ARCH_HAS_CPU_RELAX */
	212
4f86d3a8 LB	213	/**
	214	* cpuidle_enable_device - enables idle PM for a CPU
	215	* @dev: the CPU
	216	*
	217	* This function must be called between cpuidle_pause_and_lock and
	218	* cpuidle_resume_and_unlock when used externally.
	219	*/
	220	int cpuidle_enable_device(struct cpuidle_device *dev)
	221	{
	222	int ret, i;
	223
	224	if (dev->enabled)
	225	return 0;
752138df	226	if (!cpuidle_get_driver() \|\| !cpuidle_curr_governor)
4f86d3a8 LB	227	return -EIO;
	228	if (!dev->state_count)
	229	return -EINVAL;
	230
dcb84f33 VP	231	if (dev->registered == 0) {
	232	ret = __cpuidle_register_device(dev);
	233	if (ret)
	234	return ret;
	235	}
	236
d8c216cf RW	237	poll_idle_init(dev);
d8c216cf RW	238
4f86d3a8 LB	239	if ((ret = cpuidle_add_state_sysfs(dev)))
	240	return ret;
	241
	242	if (cpuidle_curr_governor->enable &&
	243	(ret = cpuidle_curr_governor->enable(dev)))
	244	goto fail_sysfs;
	245
	246	for (i = 0; i < dev->state_count; i++) {
	247	dev->states[i].usage = 0;
	248	dev->states[i].time = 0;
	249	}
	250	dev->last_residency = 0;
	251	dev->last_state = NULL;
	252
	253	smp_wmb();
	254
	255	dev->enabled = 1;
	256
	257	enabled_devices++;
	258	return 0;
	259
	260	fail_sysfs:
	261	cpuidle_remove_state_sysfs(dev);
	262
	263	return ret;
	264	}
	265
	266	EXPORT_SYMBOL_GPL(cpuidle_enable_device);
	267
	268	/**
	269	* cpuidle_disable_device - disables idle PM for a CPU
	270	* @dev: the CPU
	271	*
	272	* This function must be called between cpuidle_pause_and_lock and
	273	* cpuidle_resume_and_unlock when used externally.
	274	*/
	275	void cpuidle_disable_device(struct cpuidle_device *dev)
	276	{
	277	if (!dev->enabled)
	278	return;
752138df	279	if (!cpuidle_get_driver() \|\| !cpuidle_curr_governor)
4f86d3a8 LB	280	return;
	281
	282	dev->enabled = 0;
	283
	284	if (cpuidle_curr_governor->disable)
	285	cpuidle_curr_governor->disable(dev);
	286
	287	cpuidle_remove_state_sysfs(dev);
	288	enabled_devices--;
	289	}
	290
	291	EXPORT_SYMBOL_GPL(cpuidle_disable_device);
	292
	293	/**
dcb84f33 VP	294	* __cpuidle_register_device - internal register function called before register
dcb84f33 VP	295	* and enable routines
4f86d3a8	296	* @dev: the cpu
dcb84f33 VP	297	*
dcb84f33 VP	298	* cpuidle_lock mutex must be held before this is called
4f86d3a8	299	*/
dcb84f33	300	static int __cpuidle_register_device(struct cpuidle_device *dev)
4f86d3a8 LB	301	{
	302	int ret;
	303	struct sys_device *sys_dev = get_cpu_sysdev((unsigned long)dev->cpu);
752138df	304	struct cpuidle_driver *cpuidle_driver = cpuidle_get_driver();
4f86d3a8 LB	305
	306	if (!sys_dev)
	307	return -EINVAL;
752138df	308	if (!try_module_get(cpuidle_driver->owner))
4f86d3a8 LB	309	return -EINVAL;
	310
	311	init_completion(&dev->kobj_unregister);
	312
71abbbf8 AL	313	/*
	314	* cpuidle driver should set the dev->power_specified bit
	315	* before registering the device if the driver provides
	316	* power_usage numbers.
	317	*
	318	* For those devices whose ->power_specified is not set,
	319	* we fill in power_usage with decreasing values as the
	320	* cpuidle code has an implicit assumption that state Cn
	321	* uses less power than C(n-1).
	322	*
	323	* With CONFIG_ARCH_HAS_CPU_RELAX, C0 is already assigned
	324	* an power value of -1. So we use -2, -3, etc, for other
	325	* c-states.
	326	*/
	327	if (!dev->power_specified) {
	328	int i;
	329	for (i = CPUIDLE_DRIVER_STATE_START; i < dev->state_count; i++)
	330	dev->states[i].power_usage = -1 - i;
	331	}
	332
4f86d3a8 LB	333	per_cpu(cpuidle_devices, dev->cpu) = dev;
	334	list_add(&dev->device_list, &cpuidle_detected_devices);
	335	if ((ret = cpuidle_add_sysfs(sys_dev))) {
752138df	336	module_put(cpuidle_driver->owner);
4f86d3a8 LB	337	return ret;
	338	}
	339
dcb84f33 VP	340	dev->registered = 1;
	341	return 0;
	342	}
	343
	344	/**
	345	* cpuidle_register_device - registers a CPU's idle PM feature
	346	* @dev: the cpu
	347	*/
	348	int cpuidle_register_device(struct cpuidle_device *dev)
	349	{
	350	int ret;
	351
	352	mutex_lock(&cpuidle_lock);
	353
	354	if ((ret = __cpuidle_register_device(dev))) {
	355	mutex_unlock(&cpuidle_lock);
	356	return ret;
	357	}
	358
4f86d3a8 LB	359	cpuidle_enable_device(dev);
	360	cpuidle_install_idle_handler();
	361
	362	mutex_unlock(&cpuidle_lock);
	363
	364	return 0;
	365
	366	}
	367
	368	EXPORT_SYMBOL_GPL(cpuidle_register_device);
	369
	370	/**
	371	* cpuidle_unregister_device - unregisters a CPU's idle PM feature
	372	* @dev: the cpu
	373	*/
	374	void cpuidle_unregister_device(struct cpuidle_device *dev)
	375	{
	376	struct sys_device *sys_dev = get_cpu_sysdev((unsigned long)dev->cpu);
752138df	377	struct cpuidle_driver *cpuidle_driver = cpuidle_get_driver();
4f86d3a8	378
dcb84f33 VP	379	if (dev->registered == 0)
	380	return;
	381
4f86d3a8 LB	382	cpuidle_pause_and_lock();
	383
	384	cpuidle_disable_device(dev);
	385
	386	cpuidle_remove_sysfs(sys_dev);
	387	list_del(&dev->device_list);
	388	wait_for_completion(&dev->kobj_unregister);
	389	per_cpu(cpuidle_devices, dev->cpu) = NULL;
	390
	391	cpuidle_resume_and_unlock();
	392
752138df	393	module_put(cpuidle_driver->owner);
4f86d3a8 LB	394	}
	395
	396	EXPORT_SYMBOL_GPL(cpuidle_unregister_device);
	397
	398	#ifdef CONFIG_SMP
	399
	400	static void smp_callback(void *v)
	401	{
	402	/* we already woke the CPU up, nothing more to do */
	403	}
	404
	405	/*
	406	* This function gets called when a part of the kernel has a new latency
	407	* requirement. This means we need to get all processors out of their C-state,
	408	* and then recalculate a new suitable C-state. Just do a cross-cpu IPI; that
	409	* wakes them all right up.
	410	*/
	411	static int cpuidle_latency_notify(struct notifier_block *b,
	412	unsigned long l, void *v)
	413	{
8691e5a8	414	smp_call_function(smp_callback, NULL, 1);
4f86d3a8 LB	415	return NOTIFY_OK;
	416	}
	417
	418	static struct notifier_block cpuidle_latency_notifier = {
	419	.notifier_call = cpuidle_latency_notify,
	420	};
	421
d82b3518 MG	422	static inline void latency_notifier_init(struct notifier_block *n)
	423	{
	424	pm_qos_add_notifier(PM_QOS_CPU_DMA_LATENCY, n);
	425	}
4f86d3a8 LB	426
	427	#else /* CONFIG_SMP */
	428
	429	#define latency_notifier_init(x) do { } while (0)
	430
	431	#endif /* CONFIG_SMP */
	432
	433	/**
	434	* cpuidle_init - core initializer
	435	*/
	436	static int __init cpuidle_init(void)
	437	{
	438	int ret;
	439
62027aea LB	440	if (cpuidle_disabled())
	441	return -ENODEV;
	442
4f86d3a8 LB	443	ret = cpuidle_add_class_sysfs(&cpu_sysdev_class);
	444	if (ret)
	445	return ret;
	446
	447	latency_notifier_init(&cpuidle_latency_notifier);
	448
	449	return 0;
	450	}
	451
62027aea	452	module_param(off, int, 0444);
4f86d3a8	453	core_initcall(cpuidle_init);