[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);

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_play_dead - cpu off-lining
 *
 * Returns in case of an error or no driver
 */
int cpuidle_play_dead(void)
{
	struct cpuidle_device *dev = __this_cpu_read(cpuidle_devices);
	struct cpuidle_driver *drv = cpuidle_get_driver();
	int i, dead_state = -1;
	int power_usage = -1;

	if (!drv)
		return -ENODEV;

	/* Find lowest-power state that supports long-term idle */
	for (i = CPUIDLE_DRIVER_STATE_START; i < drv->state_count; i++) {
		struct cpuidle_state *s = &drv->states[i];

		if (s->power_usage < power_usage && s->enter_dead) {
			power_usage = s->power_usage;
			dead_state = i;
		}
	}

	if (dead_state != -1)
		return drv->states[dead_state].enter_dead(dev, dead_state);

	return -ENODEV;
}

/**
 * cpuidle_enter_state - enter the state and update stats
 * @dev: cpuidle device for this cpu
 * @drv: cpuidle driver for this cpu
 * @next_state: index into drv->states of the state to enter
 */
int cpuidle_enter_state(struct cpuidle_device *dev, struct cpuidle_driver *drv,
		int next_state)
{
	int entered_state;

	entered_state = cpuidle_enter_ops(dev, drv, next_state);

	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;
	}

	return entered_state;
}

/**
 * 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_rcuidle(POWER_CSTATE, next_state, dev->cpu);
	trace_cpu_idle_rcuidle(next_state, dev->cpu);

	entered_state = cpuidle_enter_state(dev, drv, next_state);

	trace_power_end_rcuidle(dev->cpu);
	trace_cpu_idle_rcuidle(PWR_EVENT_EXIT, dev->cpu);

	/* 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);
	ret = cpuidle_add_sysfs(cpu_dev);
	if (ret)
		goto err_sysfs;

	dev->registered = 1;
	return 0;

err_sysfs:
	list_del(&dev->device_list);
	per_cpu(cpuidle_devices, dev->cpu) = NULL;
	module_put(cpuidle_driver->owner);
	return ret;
}

/**
 * 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
1a022e3f BO	74	/**
	75	* cpuidle_play_dead - cpu off-lining
	76	*
ee01e663	77	* Returns in case of an error or no driver
1a022e3f BO	78	*/
	79	int cpuidle_play_dead(void)
	80	{
	81	struct cpuidle_device *dev = __this_cpu_read(cpuidle_devices);
	82	struct cpuidle_driver *drv = cpuidle_get_driver();
	83	int i, dead_state = -1;
	84	int power_usage = -1;
	85
ee01e663 TK	86	if (!drv)
	87	return -ENODEV;
	88
1a022e3f BO	89	/* Find lowest-power state that supports long-term idle */
	90	for (i = CPUIDLE_DRIVER_STATE_START; i < drv->state_count; i++) {
	91	struct cpuidle_state *s = &drv->states[i];
	92
	93	if (s->power_usage < power_usage && s->enter_dead) {
	94	power_usage = s->power_usage;
	95	dead_state = i;
	96	}
	97	}
	98
	99	if (dead_state != -1)
	100	return drv->states[dead_state].enter_dead(dev, dead_state);
	101
	102	return -ENODEV;
	103	}
	104
56cfbf74 CC	105	/**
	106	* cpuidle_enter_state - enter the state and update stats
	107	* @dev: cpuidle device for this cpu
	108	* @drv: cpuidle driver for this cpu
	109	* @next_state: index into drv->states of the state to enter
	110	*/
	111	int cpuidle_enter_state(struct cpuidle_device dev, struct cpuidle_driver drv,
	112	int next_state)
	113	{
	114	int entered_state;
	115
	116	entered_state = cpuidle_enter_ops(dev, drv, next_state);
	117
	118	if (entered_state >= 0) {
	119	/* Update cpuidle counters */
	120	/* This can be moved to within driver enter routine
	121	* but that results in multiple copies of same code.
	122	*/
	123	dev->states_usage[entered_state].time +=
	124	(unsigned long long)dev->last_residency;
	125	dev->states_usage[entered_state].usage++;
	126	} else {
	127	dev->last_residency = 0;
	128	}
	129
	130	return entered_state;
	131	}
	132
4f86d3a8 LB	133	/**
	134	* cpuidle_idle_call - the main idle loop
	135	*
	136	* NOTE: no locks or semaphores should be used here
a0bfa137	137	* return non-zero on failure
4f86d3a8	138	*/
a0bfa137	139	int cpuidle_idle_call(void)
4f86d3a8	140	{
4a6f4fe8	141	struct cpuidle_device *dev = __this_cpu_read(cpuidle_devices);
46bcfad7	142	struct cpuidle_driver *drv = cpuidle_get_driver();
e978aa7d	143	int next_state, entered_state;
4f86d3a8	144
a0bfa137 LB	145	if (off)
	146	return -ENODEV;
	147
	148	if (!initialized)
	149	return -ENODEV;
	150
4f86d3a8	151	/* check if the device is ready */
a0bfa137 LB	152	if (!dev \|\| !dev->enabled)
a0bfa137 LB	153	return -EBUSY;
4f86d3a8	154
9a655837 AV	155	#if 0
9a655837 AV	156	/* shows regressions, re-enable for 2.6.29 */
2e94d1f7 AV	157	/*
	158	* run any timers that can be run now, at this point
	159	* before calculating the idle duration etc.
	160	*/
	161	hrtimer_peek_ahead_timers();
9a655837	162	#endif
71abbbf8	163
4f86d3a8	164	/* ask the governor for the next state */
46bcfad7	165	next_state = cpuidle_curr_governor->select(drv, dev);
246eb7f0 KH	166	if (need_resched()) {
246eb7f0 KH	167	local_irq_enable();
a0bfa137	168	return 0;
246eb7f0 KH	169	}
246eb7f0 KH	170
76027ea8 SR	171	trace_power_start_rcuidle(POWER_CSTATE, next_state, dev->cpu);
76027ea8 SR	172	trace_cpu_idle_rcuidle(next_state, dev->cpu);
f77cfe4e	173
56cfbf74	174	entered_state = cpuidle_enter_state(dev, drv, next_state);
f77cfe4e	175
76027ea8 SR	176	trace_power_end_rcuidle(dev->cpu);
76027ea8 SR	177	trace_cpu_idle_rcuidle(PWR_EVENT_EXIT, dev->cpu);
f77cfe4e	178
4f86d3a8 LB	179	/* give the governor an opportunity to reflect on the outcome */
4f86d3a8 LB	180	if (cpuidle_curr_governor->reflect)
e978aa7d	181	cpuidle_curr_governor->reflect(dev, entered_state);
a0bfa137 LB	182
a0bfa137 LB	183	return 0;
4f86d3a8 LB	184	}
	185
	186	/**
	187	* cpuidle_install_idle_handler - installs the cpuidle idle loop handler
	188	*/
	189	void cpuidle_install_idle_handler(void)
	190	{
a0bfa137	191	if (enabled_devices) {
4f86d3a8 LB	192	/* Make sure all changes finished before we switch to new idle */
4f86d3a8 LB	193	smp_wmb();
a0bfa137	194	initialized = 1;
4f86d3a8 LB	195	}
	196	}
	197
	198	/**
	199	* cpuidle_uninstall_idle_handler - uninstalls the cpuidle idle loop handler
	200	*/
	201	void cpuidle_uninstall_idle_handler(void)
	202	{
a0bfa137 LB	203	if (enabled_devices) {
a0bfa137 LB	204	initialized = 0;
a6869cc4	205	cpuidle_kick_cpus();
4f86d3a8 LB	206	}
	207	}
	208
	209	/**
	210	* cpuidle_pause_and_lock - temporarily disables CPUIDLE
	211	*/
	212	void cpuidle_pause_and_lock(void)
	213	{
	214	mutex_lock(&cpuidle_lock);
	215	cpuidle_uninstall_idle_handler();
	216	}
	217
	218	EXPORT_SYMBOL_GPL(cpuidle_pause_and_lock);
	219
	220	/**
	221	* cpuidle_resume_and_unlock - resumes CPUIDLE operation
	222	*/
	223	void cpuidle_resume_and_unlock(void)
	224	{
	225	cpuidle_install_idle_handler();
	226	mutex_unlock(&cpuidle_lock);
	227	}
	228
	229	EXPORT_SYMBOL_GPL(cpuidle_resume_and_unlock);
	230
e1689795 RL	231	/**
	232	* cpuidle_wrap_enter - performs timekeeping and irqen around enter function
	233	* @dev: pointer to a valid cpuidle_device object
	234	* @drv: pointer to a valid cpuidle_driver object
	235	* @index: index of the target cpuidle state.
	236	*/
	237	int cpuidle_wrap_enter(struct cpuidle_device *dev,
	238	struct cpuidle_driver *drv, int index,
	239	int (enter)(struct cpuidle_device dev,
	240	struct cpuidle_driver *drv, int index))
	241	{
	242	ktime_t time_start, time_end;
	243	s64 diff;
	244
	245	time_start = ktime_get();
	246
	247	index = enter(dev, drv, index);
	248
	249	time_end = ktime_get();
	250
	251	local_irq_enable();
	252
	253	diff = ktime_to_us(ktime_sub(time_end, time_start));
	254	if (diff > INT_MAX)
	255	diff = INT_MAX;
	256
	257	dev->last_residency = (int) diff;
	258
	259	return index;
	260	}
	261
d8c216cf	262	#ifdef CONFIG_ARCH_HAS_CPU_RELAX
46bcfad7 DD	263	static int poll_idle(struct cpuidle_device *dev,
46bcfad7 DD	264	struct cpuidle_driver *drv, int index)
d8c216cf RW	265	{
	266	ktime_t t1, t2;
	267	s64 diff;
d8c216cf RW	268
	269	t1 = ktime_get();
	270	local_irq_enable();
	271	while (!need_resched())
	272	cpu_relax();
	273
	274	t2 = ktime_get();
	275	diff = ktime_to_us(ktime_sub(t2, t1));
	276	if (diff > INT_MAX)
	277	diff = INT_MAX;
	278
e978aa7d DD	279	dev->last_residency = (int) diff;
	280
	281	return index;
d8c216cf RW	282	}
d8c216cf RW	283
46bcfad7	284	static void poll_idle_init(struct cpuidle_driver *drv)
d8c216cf	285	{
46bcfad7	286	struct cpuidle_state *state = &drv->states[0];
d8c216cf	287
720f1c30	288	snprintf(state->name, CPUIDLE_NAME_LEN, "POLL");
d8c216cf RW	289	snprintf(state->desc, CPUIDLE_DESC_LEN, "CPUIDLE CORE POLL IDLE");
	290	state->exit_latency = 0;
	291	state->target_residency = 0;
	292	state->power_usage = -1;
d247632c	293	state->flags = 0;
d8c216cf	294	state->enter = poll_idle;
3a53396b	295	state->disable = 0;
d8c216cf RW	296	}
d8c216cf RW	297	#else
46bcfad7	298	static void poll_idle_init(struct cpuidle_driver *drv) {}
d8c216cf RW	299	#endif /* CONFIG_ARCH_HAS_CPU_RELAX */
d8c216cf RW	300
4f86d3a8 LB	301	/**
	302	* cpuidle_enable_device - enables idle PM for a CPU
	303	* @dev: the CPU
	304	*
	305	* This function must be called between cpuidle_pause_and_lock and
	306	* cpuidle_resume_and_unlock when used externally.
	307	*/
	308	int cpuidle_enable_device(struct cpuidle_device *dev)
	309	{
	310	int ret, i;
e1689795	311	struct cpuidle_driver *drv = cpuidle_get_driver();
4f86d3a8 LB	312
	313	if (dev->enabled)
	314	return 0;
e1689795	315	if (!drv \|\| !cpuidle_curr_governor)
4f86d3a8 LB	316	return -EIO;
4f86d3a8 LB	317	if (!dev->state_count)
fc850f39	318	dev->state_count = drv->state_count;
4f86d3a8	319
dcb84f33 VP	320	if (dev->registered == 0) {
	321	ret = __cpuidle_register_device(dev);
	322	if (ret)
	323	return ret;
	324	}
	325
e1689795 RL	326	cpuidle_enter_ops = drv->en_core_tk_irqen ?
	327	cpuidle_enter_tk : cpuidle_enter;
	328
	329	poll_idle_init(drv);
d8c216cf	330
4f86d3a8 LB	331	if ((ret = cpuidle_add_state_sysfs(dev)))
	332	return ret;
	333
	334	if (cpuidle_curr_governor->enable &&
e1689795	335	(ret = cpuidle_curr_governor->enable(drv, dev)))
4f86d3a8 LB	336	goto fail_sysfs;
	337
	338	for (i = 0; i < dev->state_count; i++) {
4202735e DD	339	dev->states_usage[i].usage = 0;
4202735e DD	340	dev->states_usage[i].time = 0;
4f86d3a8 LB	341	}
4f86d3a8 LB	342	dev->last_residency = 0;
4f86d3a8 LB	343
	344	smp_wmb();
	345
	346	dev->enabled = 1;
	347
	348	enabled_devices++;
	349	return 0;
	350
	351	fail_sysfs:
	352	cpuidle_remove_state_sysfs(dev);
	353
	354	return ret;
	355	}
	356
	357	EXPORT_SYMBOL_GPL(cpuidle_enable_device);
	358
	359	/**
	360	* cpuidle_disable_device - disables idle PM for a CPU
	361	* @dev: the CPU
	362	*
	363	* This function must be called between cpuidle_pause_and_lock and
	364	* cpuidle_resume_and_unlock when used externally.
	365	*/
	366	void cpuidle_disable_device(struct cpuidle_device *dev)
	367	{
	368	if (!dev->enabled)
	369	return;
752138df	370	if (!cpuidle_get_driver() \|\| !cpuidle_curr_governor)
4f86d3a8 LB	371	return;
	372
	373	dev->enabled = 0;
	374
	375	if (cpuidle_curr_governor->disable)
46bcfad7	376	cpuidle_curr_governor->disable(cpuidle_get_driver(), dev);
4f86d3a8 LB	377
	378	cpuidle_remove_state_sysfs(dev);
	379	enabled_devices--;
	380	}
	381
	382	EXPORT_SYMBOL_GPL(cpuidle_disable_device);
	383
	384	/**
dcb84f33 VP	385	* __cpuidle_register_device - internal register function called before register
dcb84f33 VP	386	* and enable routines
4f86d3a8	387	* @dev: the cpu
dcb84f33 VP	388	*
dcb84f33 VP	389	* cpuidle_lock mutex must be held before this is called
4f86d3a8	390	*/
dcb84f33	391	static int __cpuidle_register_device(struct cpuidle_device *dev)
4f86d3a8 LB	392	{
4f86d3a8 LB	393	int ret;
8a25a2fd	394	struct device *cpu_dev = get_cpu_device((unsigned long)dev->cpu);
752138df	395	struct cpuidle_driver *cpuidle_driver = cpuidle_get_driver();
4f86d3a8	396
8a25a2fd	397	if (!dev)
4f86d3a8	398	return -EINVAL;
752138df	399	if (!try_module_get(cpuidle_driver->owner))
4f86d3a8 LB	400	return -EINVAL;
	401
	402	init_completion(&dev->kobj_unregister);
	403
4f86d3a8 LB	404	per_cpu(cpuidle_devices, dev->cpu) = dev;
4f86d3a8 LB	405	list_add(&dev->device_list, &cpuidle_detected_devices);
3af272ab CC	406	ret = cpuidle_add_sysfs(cpu_dev);
	407	if (ret)
	408	goto err_sysfs;
4f86d3a8	409
dcb84f33 VP	410	dev->registered = 1;
dcb84f33 VP	411	return 0;
3af272ab CC	412
	413	err_sysfs:
	414	list_del(&dev->device_list);
	415	per_cpu(cpuidle_devices, dev->cpu) = NULL;
	416	module_put(cpuidle_driver->owner);
	417	return ret;
dcb84f33 VP	418	}
	419
	420	/**
	421	* cpuidle_register_device - registers a CPU's idle PM feature
	422	* @dev: the cpu
	423	*/
	424	int cpuidle_register_device(struct cpuidle_device *dev)
	425	{
	426	int ret;
	427
	428	mutex_lock(&cpuidle_lock);
	429
	430	if ((ret = __cpuidle_register_device(dev))) {
	431	mutex_unlock(&cpuidle_lock);
	432	return ret;
	433	}
	434
4f86d3a8 LB	435	cpuidle_enable_device(dev);
	436	cpuidle_install_idle_handler();
	437
	438	mutex_unlock(&cpuidle_lock);
	439
	440	return 0;
	441
	442	}
	443
	444	EXPORT_SYMBOL_GPL(cpuidle_register_device);
	445
	446	/**
	447	* cpuidle_unregister_device - unregisters a CPU's idle PM feature
	448	* @dev: the cpu
	449	*/
	450	void cpuidle_unregister_device(struct cpuidle_device *dev)
	451	{
8a25a2fd	452	struct device *cpu_dev = get_cpu_device((unsigned long)dev->cpu);
752138df	453	struct cpuidle_driver *cpuidle_driver = cpuidle_get_driver();
4f86d3a8	454
dcb84f33 VP	455	if (dev->registered == 0)
	456	return;
	457
4f86d3a8 LB	458	cpuidle_pause_and_lock();
	459
	460	cpuidle_disable_device(dev);
	461
8a25a2fd	462	cpuidle_remove_sysfs(cpu_dev);
4f86d3a8 LB	463	list_del(&dev->device_list);
	464	wait_for_completion(&dev->kobj_unregister);
	465	per_cpu(cpuidle_devices, dev->cpu) = NULL;
	466
	467	cpuidle_resume_and_unlock();
	468
752138df	469	module_put(cpuidle_driver->owner);
4f86d3a8 LB	470	}
	471
	472	EXPORT_SYMBOL_GPL(cpuidle_unregister_device);
	473
	474	#ifdef CONFIG_SMP
	475
	476	static void smp_callback(void *v)
	477	{
	478	/* we already woke the CPU up, nothing more to do */
	479	}
	480
	481	/*
	482	* This function gets called when a part of the kernel has a new latency
	483	* requirement. This means we need to get all processors out of their C-state,
	484	* and then recalculate a new suitable C-state. Just do a cross-cpu IPI; that
	485	* wakes them all right up.
	486	*/
	487	static int cpuidle_latency_notify(struct notifier_block *b,
	488	unsigned long l, void *v)
	489	{
8691e5a8	490	smp_call_function(smp_callback, NULL, 1);
4f86d3a8 LB	491	return NOTIFY_OK;
	492	}
	493
	494	static struct notifier_block cpuidle_latency_notifier = {
	495	.notifier_call = cpuidle_latency_notify,
	496	};
	497
d82b3518 MG	498	static inline void latency_notifier_init(struct notifier_block *n)
	499	{
	500	pm_qos_add_notifier(PM_QOS_CPU_DMA_LATENCY, n);
	501	}
4f86d3a8 LB	502
	503	#else /* CONFIG_SMP */
	504
	505	#define latency_notifier_init(x) do { } while (0)
	506
	507	#endif /* CONFIG_SMP */
	508
	509	/**
	510	* cpuidle_init - core initializer
	511	*/
	512	static int __init cpuidle_init(void)
	513	{
	514	int ret;
	515
62027aea LB	516	if (cpuidle_disabled())
	517	return -ENODEV;
	518
8a25a2fd	519	ret = cpuidle_add_interface(cpu_subsys.dev_root);
4f86d3a8 LB	520	if (ret)
	521	return ret;
	522
	523	latency_notifier_init(&cpuidle_latency_notifier);
	524
	525	return 0;
	526	}
	527
62027aea	528	module_param(off, int, 0444);
4f86d3a8	529	core_initcall(cpuidle_init);