[mirror_ubuntu-artful-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.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);

static inline int cpuidle_enter(struct cpuidle_device *dev,
				struct cpuidle_driver *drv, int index)
{
	struct cpuidle_state *target_state = &drv->states[index];
	return target_state->enter(dev, drv, index);
}

static inline int cpuidle_enter_tk(struct cpuidle_device *dev,
			       struct cpuidle_driver *drv, int index)
{
	return cpuidle_wrap_enter(dev, drv, index, cpuidle_enter);
}

typedef int (*cpuidle_enter_t)(struct cpuidle_device *dev,
			       struct cpuidle_driver *drv, int index);

static cpuidle_enter_t cpuidle_enter_ops;

/**
 * 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();
	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;
	}

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

	entered_state = cpuidle_enter_ops(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++;
	} else {
		dev->last_residency = 0;
	}

	/* 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);

/**
 * cpuidle_wrap_enter - performs timekeeping and irqen around enter function
 * @dev: pointer to a valid cpuidle_device object
 * @drv: pointer to a valid cpuidle_driver object
 * @index: index of the target cpuidle state.
 */
int cpuidle_wrap_enter(struct cpuidle_device *dev,
				struct cpuidle_driver *drv, int index,
				int (*enter)(struct cpuidle_device *dev,
					struct cpuidle_driver *drv, int index))
{
	ktime_t time_start, time_end;
	s64 diff;

	time_start = ktime_get();

	index = enter(dev, drv, index);

	time_end = ktime_get();

	local_irq_enable();

	diff = ktime_to_us(ktime_sub(time_end, time_start));
	if (diff > INT_MAX)
		diff = INT_MAX;

	dev->last_residency = (int) diff;

	return index;
}

#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;
	state->disable = 0;
}
#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;
	struct cpuidle_driver *drv = cpuidle_get_driver();

	if (dev->enabled)
		return 0;
	if (!drv || !cpuidle_curr_governor)
		return -EIO;
	if (!dev->state_count)
		dev->state_count = drv->state_count;

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

	cpuidle_enter_ops = drv->en_core_tk_irqen ?
		cpuidle_enter_tk : cpuidle_enter;

	poll_idle_init(drv);

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

	if (cpuidle_curr_governor->enable &&
	    (ret = cpuidle_curr_governor->enable(drv, 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
e1689795 RL	56	static inline int cpuidle_enter(struct cpuidle_device *dev,
	57	struct cpuidle_driver *drv, int index)
	58	{
	59	struct cpuidle_state *target_state = &drv->states[index];
	60	return target_state->enter(dev, drv, index);
	61	}
	62
	63	static inline int cpuidle_enter_tk(struct cpuidle_device *dev,
	64	struct cpuidle_driver *drv, int index)
	65	{
	66	return cpuidle_wrap_enter(dev, drv, index, cpuidle_enter);
	67	}
	68
	69	typedef int (cpuidle_enter_t)(struct cpuidle_device dev,
	70	struct cpuidle_driver *drv, int index);
	71
	72	static cpuidle_enter_t cpuidle_enter_ops;
	73
4f86d3a8 LB	74	/**
	75	* cpuidle_idle_call - the main idle loop
	76	*
	77	* NOTE: no locks or semaphores should be used here
a0bfa137	78	* return non-zero on failure
4f86d3a8	79	*/
a0bfa137	80	int cpuidle_idle_call(void)
4f86d3a8	81	{
4a6f4fe8	82	struct cpuidle_device *dev = __this_cpu_read(cpuidle_devices);
46bcfad7	83	struct cpuidle_driver *drv = cpuidle_get_driver();
e978aa7d	84	int next_state, entered_state;
4f86d3a8	85
a0bfa137 LB	86	if (off)
	87	return -ENODEV;
	88
	89	if (!initialized)
	90	return -ENODEV;
	91
4f86d3a8	92	/* check if the device is ready */
a0bfa137 LB	93	if (!dev \|\| !dev->enabled)
a0bfa137 LB	94	return -EBUSY;
4f86d3a8	95
9a655837 AV	96	#if 0
9a655837 AV	97	/* shows regressions, re-enable for 2.6.29 */
2e94d1f7 AV	98	/*
	99	* run any timers that can be run now, at this point
	100	* before calculating the idle duration etc.
	101	*/
	102	hrtimer_peek_ahead_timers();
9a655837	103	#endif
71abbbf8	104
4f86d3a8	105	/* ask the governor for the next state */
46bcfad7	106	next_state = cpuidle_curr_governor->select(drv, dev);
246eb7f0 KH	107	if (need_resched()) {
246eb7f0 KH	108	local_irq_enable();
a0bfa137	109	return 0;
246eb7f0 KH	110	}
246eb7f0 KH	111
f77cfe4e TR	112	trace_power_start(POWER_CSTATE, next_state, dev->cpu);
	113	trace_cpu_idle(next_state, dev->cpu);
	114
e1689795	115	entered_state = cpuidle_enter_ops(dev, drv, next_state);
f77cfe4e TR	116
	117	trace_power_end(dev->cpu);
	118	trace_cpu_idle(PWR_EVENT_EXIT, dev->cpu);
	119
e978aa7d DD	120	if (entered_state >= 0) {
	121	/* Update cpuidle counters */
	122	/* This can be moved to within driver enter routine
	123	* but that results in multiple copies of same code.
	124	*/
4202735e	125	dev->states_usage[entered_state].time +=
e978aa7d	126	(unsigned long long)dev->last_residency;
4202735e	127	dev->states_usage[entered_state].usage++;
e1689795 RL	128	} else {
e1689795 RL	129	dev->last_residency = 0;
e978aa7d	130	}
4f86d3a8 LB	131
	132	/* give the governor an opportunity to reflect on the outcome */
	133	if (cpuidle_curr_governor->reflect)
e978aa7d	134	cpuidle_curr_governor->reflect(dev, entered_state);
a0bfa137 LB	135
a0bfa137 LB	136	return 0;
4f86d3a8 LB	137	}
	138
	139	/**
	140	* cpuidle_install_idle_handler - installs the cpuidle idle loop handler
	141	*/
	142	void cpuidle_install_idle_handler(void)
	143	{
a0bfa137	144	if (enabled_devices) {
4f86d3a8 LB	145	/* Make sure all changes finished before we switch to new idle */
4f86d3a8 LB	146	smp_wmb();
a0bfa137	147	initialized = 1;
4f86d3a8 LB	148	}
	149	}
	150
	151	/**
	152	* cpuidle_uninstall_idle_handler - uninstalls the cpuidle idle loop handler
	153	*/
	154	void cpuidle_uninstall_idle_handler(void)
	155	{
a0bfa137 LB	156	if (enabled_devices) {
a0bfa137 LB	157	initialized = 0;
a6869cc4	158	cpuidle_kick_cpus();
4f86d3a8 LB	159	}
	160	}
	161
	162	/**
	163	* cpuidle_pause_and_lock - temporarily disables CPUIDLE
	164	*/
	165	void cpuidle_pause_and_lock(void)
	166	{
	167	mutex_lock(&cpuidle_lock);
	168	cpuidle_uninstall_idle_handler();
	169	}
	170
	171	EXPORT_SYMBOL_GPL(cpuidle_pause_and_lock);
	172
	173	/**
	174	* cpuidle_resume_and_unlock - resumes CPUIDLE operation
	175	*/
	176	void cpuidle_resume_and_unlock(void)
	177	{
	178	cpuidle_install_idle_handler();
	179	mutex_unlock(&cpuidle_lock);
	180	}
	181
	182	EXPORT_SYMBOL_GPL(cpuidle_resume_and_unlock);
	183
e1689795 RL	184	/**
	185	* cpuidle_wrap_enter - performs timekeeping and irqen around enter function
	186	* @dev: pointer to a valid cpuidle_device object
	187	* @drv: pointer to a valid cpuidle_driver object
	188	* @index: index of the target cpuidle state.
	189	*/
	190	int cpuidle_wrap_enter(struct cpuidle_device *dev,
	191	struct cpuidle_driver *drv, int index,
	192	int (enter)(struct cpuidle_device dev,
	193	struct cpuidle_driver *drv, int index))
	194	{
	195	ktime_t time_start, time_end;
	196	s64 diff;
	197
	198	time_start = ktime_get();
	199
	200	index = enter(dev, drv, index);
	201
	202	time_end = ktime_get();
	203
	204	local_irq_enable();
	205
	206	diff = ktime_to_us(ktime_sub(time_end, time_start));
	207	if (diff > INT_MAX)
	208	diff = INT_MAX;
	209
	210	dev->last_residency = (int) diff;
	211
	212	return index;
	213	}
	214
d8c216cf	215	#ifdef CONFIG_ARCH_HAS_CPU_RELAX
46bcfad7 DD	216	static int poll_idle(struct cpuidle_device *dev,
46bcfad7 DD	217	struct cpuidle_driver *drv, int index)
d8c216cf RW	218	{
	219	ktime_t t1, t2;
	220	s64 diff;
d8c216cf RW	221
	222	t1 = ktime_get();
	223	local_irq_enable();
	224	while (!need_resched())
	225	cpu_relax();
	226
	227	t2 = ktime_get();
	228	diff = ktime_to_us(ktime_sub(t2, t1));
	229	if (diff > INT_MAX)
	230	diff = INT_MAX;
	231
e978aa7d DD	232	dev->last_residency = (int) diff;
	233
	234	return index;
d8c216cf RW	235	}
d8c216cf RW	236
46bcfad7	237	static void poll_idle_init(struct cpuidle_driver *drv)
d8c216cf	238	{
46bcfad7	239	struct cpuidle_state *state = &drv->states[0];
d8c216cf	240
720f1c30	241	snprintf(state->name, CPUIDLE_NAME_LEN, "POLL");
d8c216cf RW	242	snprintf(state->desc, CPUIDLE_DESC_LEN, "CPUIDLE CORE POLL IDLE");
	243	state->exit_latency = 0;
	244	state->target_residency = 0;
	245	state->power_usage = -1;
d247632c	246	state->flags = 0;
d8c216cf	247	state->enter = poll_idle;
3a53396b	248	state->disable = 0;
d8c216cf RW	249	}
d8c216cf RW	250	#else
46bcfad7	251	static void poll_idle_init(struct cpuidle_driver *drv) {}
d8c216cf RW	252	#endif /* CONFIG_ARCH_HAS_CPU_RELAX */
d8c216cf RW	253
4f86d3a8 LB	254	/**
	255	* cpuidle_enable_device - enables idle PM for a CPU
	256	* @dev: the CPU
	257	*
	258	* This function must be called between cpuidle_pause_and_lock and
	259	* cpuidle_resume_and_unlock when used externally.
	260	*/
	261	int cpuidle_enable_device(struct cpuidle_device *dev)
	262	{
	263	int ret, i;
e1689795	264	struct cpuidle_driver *drv = cpuidle_get_driver();
4f86d3a8 LB	265
	266	if (dev->enabled)
	267	return 0;
e1689795	268	if (!drv \|\| !cpuidle_curr_governor)
4f86d3a8 LB	269	return -EIO;
4f86d3a8 LB	270	if (!dev->state_count)
fc850f39	271	dev->state_count = drv->state_count;
4f86d3a8	272
dcb84f33 VP	273	if (dev->registered == 0) {
	274	ret = __cpuidle_register_device(dev);
	275	if (ret)
	276	return ret;
	277	}
	278
e1689795 RL	279	cpuidle_enter_ops = drv->en_core_tk_irqen ?
	280	cpuidle_enter_tk : cpuidle_enter;
	281
	282	poll_idle_init(drv);
d8c216cf	283
4f86d3a8 LB	284	if ((ret = cpuidle_add_state_sysfs(dev)))
	285	return ret;
	286
	287	if (cpuidle_curr_governor->enable &&
e1689795	288	(ret = cpuidle_curr_governor->enable(drv, dev)))
4f86d3a8 LB	289	goto fail_sysfs;
	290
	291	for (i = 0; i < dev->state_count; i++) {
4202735e DD	292	dev->states_usage[i].usage = 0;
4202735e DD	293	dev->states_usage[i].time = 0;
4f86d3a8 LB	294	}
4f86d3a8 LB	295	dev->last_residency = 0;
4f86d3a8 LB	296
	297	smp_wmb();
	298
	299	dev->enabled = 1;
	300
	301	enabled_devices++;
	302	return 0;
	303
	304	fail_sysfs:
	305	cpuidle_remove_state_sysfs(dev);
	306
	307	return ret;
	308	}
	309
	310	EXPORT_SYMBOL_GPL(cpuidle_enable_device);
	311
	312	/**
	313	* cpuidle_disable_device - disables idle PM for a CPU
	314	* @dev: the CPU
	315	*
	316	* This function must be called between cpuidle_pause_and_lock and
	317	* cpuidle_resume_and_unlock when used externally.
	318	*/
	319	void cpuidle_disable_device(struct cpuidle_device *dev)
	320	{
	321	if (!dev->enabled)
	322	return;
752138df	323	if (!cpuidle_get_driver() \|\| !cpuidle_curr_governor)
4f86d3a8 LB	324	return;
	325
	326	dev->enabled = 0;
	327
	328	if (cpuidle_curr_governor->disable)
46bcfad7	329	cpuidle_curr_governor->disable(cpuidle_get_driver(), dev);
4f86d3a8 LB	330
	331	cpuidle_remove_state_sysfs(dev);
	332	enabled_devices--;
	333	}
	334
	335	EXPORT_SYMBOL_GPL(cpuidle_disable_device);
	336
	337	/**
dcb84f33 VP	338	* __cpuidle_register_device - internal register function called before register
dcb84f33 VP	339	* and enable routines
4f86d3a8	340	* @dev: the cpu
dcb84f33 VP	341	*
dcb84f33 VP	342	* cpuidle_lock mutex must be held before this is called
4f86d3a8	343	*/
dcb84f33	344	static int __cpuidle_register_device(struct cpuidle_device *dev)
4f86d3a8 LB	345	{
4f86d3a8 LB	346	int ret;
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
8a25a2fd	350	if (!dev)
4f86d3a8	351	return -EINVAL;
752138df	352	if (!try_module_get(cpuidle_driver->owner))
4f86d3a8 LB	353	return -EINVAL;
	354
	355	init_completion(&dev->kobj_unregister);
	356
4f86d3a8 LB	357	per_cpu(cpuidle_devices, dev->cpu) = dev;
4f86d3a8 LB	358	list_add(&dev->device_list, &cpuidle_detected_devices);
8a25a2fd	359	if ((ret = cpuidle_add_sysfs(cpu_dev))) {
752138df	360	module_put(cpuidle_driver->owner);
4f86d3a8 LB	361	return ret;
	362	}
	363
dcb84f33 VP	364	dev->registered = 1;
	365	return 0;
	366	}
	367
	368	/**
	369	* cpuidle_register_device - registers a CPU's idle PM feature
	370	* @dev: the cpu
	371	*/
	372	int cpuidle_register_device(struct cpuidle_device *dev)
	373	{
	374	int ret;
	375
	376	mutex_lock(&cpuidle_lock);
	377
	378	if ((ret = __cpuidle_register_device(dev))) {
	379	mutex_unlock(&cpuidle_lock);
	380	return ret;
	381	}
	382
4f86d3a8 LB	383	cpuidle_enable_device(dev);
	384	cpuidle_install_idle_handler();
	385
	386	mutex_unlock(&cpuidle_lock);
	387
	388	return 0;
	389
	390	}
	391
	392	EXPORT_SYMBOL_GPL(cpuidle_register_device);
	393
	394	/**
	395	* cpuidle_unregister_device - unregisters a CPU's idle PM feature
	396	* @dev: the cpu
	397	*/
	398	void cpuidle_unregister_device(struct cpuidle_device *dev)
	399	{
8a25a2fd	400	struct device *cpu_dev = get_cpu_device((unsigned long)dev->cpu);
752138df	401	struct cpuidle_driver *cpuidle_driver = cpuidle_get_driver();
4f86d3a8	402
dcb84f33 VP	403	if (dev->registered == 0)
	404	return;
	405
4f86d3a8 LB	406	cpuidle_pause_and_lock();
	407
	408	cpuidle_disable_device(dev);
	409
8a25a2fd	410	cpuidle_remove_sysfs(cpu_dev);
4f86d3a8 LB	411	list_del(&dev->device_list);
	412	wait_for_completion(&dev->kobj_unregister);
	413	per_cpu(cpuidle_devices, dev->cpu) = NULL;
	414
	415	cpuidle_resume_and_unlock();
	416
752138df	417	module_put(cpuidle_driver->owner);
4f86d3a8 LB	418	}
	419
	420	EXPORT_SYMBOL_GPL(cpuidle_unregister_device);
	421
	422	#ifdef CONFIG_SMP
	423
	424	static void smp_callback(void *v)
	425	{
	426	/* we already woke the CPU up, nothing more to do */
	427	}
	428
	429	/*
	430	* This function gets called when a part of the kernel has a new latency
	431	* requirement. This means we need to get all processors out of their C-state,
	432	* and then recalculate a new suitable C-state. Just do a cross-cpu IPI; that
	433	* wakes them all right up.
	434	*/
	435	static int cpuidle_latency_notify(struct notifier_block *b,
	436	unsigned long l, void *v)
	437	{
8691e5a8	438	smp_call_function(smp_callback, NULL, 1);
4f86d3a8 LB	439	return NOTIFY_OK;
	440	}
	441
	442	static struct notifier_block cpuidle_latency_notifier = {
	443	.notifier_call = cpuidle_latency_notify,
	444	};
	445
d82b3518 MG	446	static inline void latency_notifier_init(struct notifier_block *n)
	447	{
	448	pm_qos_add_notifier(PM_QOS_CPU_DMA_LATENCY, n);
	449	}
4f86d3a8 LB	450
	451	#else /* CONFIG_SMP */
	452
	453	#define latency_notifier_init(x) do { } while (0)
	454
	455	#endif /* CONFIG_SMP */
	456
	457	/**
	458	* cpuidle_init - core initializer
	459	*/
	460	static int __init cpuidle_init(void)
	461	{
	462	int ret;
	463
62027aea LB	464	if (cpuidle_disabled())
	465	return -ENODEV;
	466
8a25a2fd	467	ret = cpuidle_add_interface(cpu_subsys.dev_root);
4f86d3a8 LB	468	if (ret)
	469	return ret;
	470
	471	latency_notifier_init(&cpuidle_latency_notifier);
	472
	473	return 0;
	474	}
	475
62027aea	476	module_param(off, int, 0444);
4f86d3a8	477	core_initcall(cpuidle_init);