[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;
}

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_cpu_driver(dev);
	int i, dead_state = -1;
	int power_usage = INT_MAX;

	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 += 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;
	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;

	drv = cpuidle_get_cpu_driver(dev);

	/* ask the governor for the next state */
	next_state = cpuidle_curr_governor->select(drv, dev);
	if (need_resched()) {
		dev->last_residency = 0;
		/* give the governor an opportunity to reflect on the outcome */
		if (cpuidle_curr_governor->reflect)
			cpuidle_curr_governor->reflect(dev, next_state);
		local_irq_enable();
		return 0;
	}

	trace_power_start_rcuidle(POWER_CSTATE, next_state, dev->cpu);
	trace_cpu_idle_rcuidle(next_state, dev->cpu);

	if (cpuidle_state_is_coupled(dev, drv, next_state))
		entered_state = cpuidle_enter_state_coupled(dev, drv,
							    next_state);
	else
		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;
		kick_all_cpus_sync();
	}
}

/**
 * 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);

/* Currently used in suspend/resume path to suspend cpuidle */
void cpuidle_pause(void)
{
	mutex_lock(&cpuidle_lock);
	cpuidle_uninstall_idle_handler();
	mutex_unlock(&cpuidle_lock);
}

/* Currently used in suspend/resume path to resume cpuidle */
void cpuidle_resume(void)
{
	mutex_lock(&cpuidle_lock);
	cpuidle_install_idle_handler();
	mutex_unlock(&cpuidle_lock);
}

/**
 * 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->disabled = false;
}
#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;

	if (!dev)
		return -EINVAL;

	if (dev->enabled)
		return 0;

	drv = cpuidle_get_cpu_driver(dev);

	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);

	ret = cpuidle_add_device_sysfs(dev);
	if (ret)
		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_device_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)
{
	struct cpuidle_driver *drv = cpuidle_get_cpu_driver(dev);

	if (!dev || !dev->enabled)
		return;

	if (!drv || !cpuidle_curr_governor)
		return;

	dev->enabled = 0;

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

	cpuidle_remove_device_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 cpuidle_driver *drv = cpuidle_get_cpu_driver(dev);

	if (!try_module_get(drv->owner))
		return -EINVAL;

	per_cpu(cpuidle_devices, dev->cpu) = dev;
	list_add(&dev->device_list, &cpuidle_detected_devices);
	ret = cpuidle_add_sysfs(dev);
	if (ret)
		goto err_sysfs;

	ret = cpuidle_coupled_register_device(dev);
	if (ret)
		goto err_coupled;

	dev->registered = 1;
	return 0;

err_coupled:
	cpuidle_remove_sysfs(dev);
err_sysfs:
	list_del(&dev->device_list);
	per_cpu(cpuidle_devices, dev->cpu) = NULL;
	module_put(drv->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;

	if (!dev)
		return -EINVAL;

	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 cpuidle_driver *drv = cpuidle_get_cpu_driver(dev);

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

	cpuidle_pause_and_lock();

	cpuidle_disable_device(dev);

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

	cpuidle_coupled_unregister_device(dev);

	cpuidle_resume_and_unlock();

	module_put(drv->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
dcb84f33 VP	43	static int __cpuidle_register_device(struct cpuidle_device *dev);
dcb84f33 VP	44
e1689795 RL	45	static inline int cpuidle_enter(struct cpuidle_device *dev,
	46	struct cpuidle_driver *drv, int index)
	47	{
	48	struct cpuidle_state *target_state = &drv->states[index];
	49	return target_state->enter(dev, drv, index);
	50	}
	51
	52	static inline int cpuidle_enter_tk(struct cpuidle_device *dev,
	53	struct cpuidle_driver *drv, int index)
	54	{
	55	return cpuidle_wrap_enter(dev, drv, index, cpuidle_enter);
	56	}
	57
	58	typedef int (cpuidle_enter_t)(struct cpuidle_device dev,
	59	struct cpuidle_driver *drv, int index);
	60
	61	static cpuidle_enter_t cpuidle_enter_ops;
	62
1a022e3f BO	63	/**
	64	* cpuidle_play_dead - cpu off-lining
	65	*
ee01e663	66	* Returns in case of an error or no driver
1a022e3f BO	67	*/
	68	int cpuidle_play_dead(void)
	69	{
	70	struct cpuidle_device *dev = __this_cpu_read(cpuidle_devices);
bf4d1b5d	71	struct cpuidle_driver *drv = cpuidle_get_cpu_driver(dev);
1a022e3f	72	int i, dead_state = -1;
0e5537b3	73	int power_usage = INT_MAX;
1a022e3f	74
ee01e663 TK	75	if (!drv)
	76	return -ENODEV;
	77
1a022e3f BO	78	/* Find lowest-power state that supports long-term idle */
	79	for (i = CPUIDLE_DRIVER_STATE_START; i < drv->state_count; i++) {
	80	struct cpuidle_state *s = &drv->states[i];
	81
	82	if (s->power_usage < power_usage && s->enter_dead) {
	83	power_usage = s->power_usage;
	84	dead_state = i;
	85	}
	86	}
	87
	88	if (dead_state != -1)
	89	return drv->states[dead_state].enter_dead(dev, dead_state);
	90
	91	return -ENODEV;
	92	}
	93
56cfbf74 CC	94	/**
	95	* cpuidle_enter_state - enter the state and update stats
	96	* @dev: cpuidle device for this cpu
	97	* @drv: cpuidle driver for this cpu
	98	* @next_state: index into drv->states of the state to enter
	99	*/
	100	int cpuidle_enter_state(struct cpuidle_device dev, struct cpuidle_driver drv,
	101	int next_state)
	102	{
	103	int entered_state;
	104
	105	entered_state = cpuidle_enter_ops(dev, drv, next_state);
	106
	107	if (entered_state >= 0) {
	108	/* Update cpuidle counters */
	109	/* This can be moved to within driver enter routine
	110	* but that results in multiple copies of same code.
	111	*/
a474a515	112	dev->states_usage[entered_state].time += dev->last_residency;
56cfbf74 CC	113	dev->states_usage[entered_state].usage++;
	114	} else {
	115	dev->last_residency = 0;
	116	}
	117
	118	return entered_state;
	119	}
	120
4f86d3a8 LB	121	/**
	122	* cpuidle_idle_call - the main idle loop
	123	*
	124	* NOTE: no locks or semaphores should be used here
a0bfa137	125	* return non-zero on failure
4f86d3a8	126	*/
a0bfa137	127	int cpuidle_idle_call(void)
4f86d3a8	128	{
4a6f4fe8	129	struct cpuidle_device *dev = __this_cpu_read(cpuidle_devices);
bf4d1b5d	130	struct cpuidle_driver *drv;
e978aa7d	131	int next_state, entered_state;
4f86d3a8	132
a0bfa137 LB	133	if (off)
	134	return -ENODEV;
	135
	136	if (!initialized)
	137	return -ENODEV;
	138
4f86d3a8	139	/* check if the device is ready */
a0bfa137 LB	140	if (!dev \|\| !dev->enabled)
a0bfa137 LB	141	return -EBUSY;
4f86d3a8	142
bf4d1b5d DL	143	drv = cpuidle_get_cpu_driver(dev);
bf4d1b5d DL	144
4f86d3a8	145	/* ask the governor for the next state */
46bcfad7	146	next_state = cpuidle_curr_governor->select(drv, dev);
246eb7f0	147	if (need_resched()) {
d73d68dc YS	148	dev->last_residency = 0;
	149	/* give the governor an opportunity to reflect on the outcome */
	150	if (cpuidle_curr_governor->reflect)
	151	cpuidle_curr_governor->reflect(dev, next_state);
246eb7f0	152	local_irq_enable();
a0bfa137	153	return 0;
246eb7f0 KH	154	}
246eb7f0 KH	155
76027ea8 SR	156	trace_power_start_rcuidle(POWER_CSTATE, next_state, dev->cpu);
76027ea8 SR	157	trace_cpu_idle_rcuidle(next_state, dev->cpu);
f77cfe4e	158
4126c019 CC	159	if (cpuidle_state_is_coupled(dev, drv, next_state))
	160	entered_state = cpuidle_enter_state_coupled(dev, drv,
	161	next_state);
	162	else
	163	entered_state = cpuidle_enter_state(dev, drv, next_state);
f77cfe4e	164
76027ea8 SR	165	trace_power_end_rcuidle(dev->cpu);
76027ea8 SR	166	trace_cpu_idle_rcuidle(PWR_EVENT_EXIT, dev->cpu);
f77cfe4e	167
4f86d3a8 LB	168	/* give the governor an opportunity to reflect on the outcome */
4f86d3a8 LB	169	if (cpuidle_curr_governor->reflect)
e978aa7d	170	cpuidle_curr_governor->reflect(dev, entered_state);
a0bfa137 LB	171
a0bfa137 LB	172	return 0;
4f86d3a8 LB	173	}
	174
	175	/**
	176	* cpuidle_install_idle_handler - installs the cpuidle idle loop handler
	177	*/
	178	void cpuidle_install_idle_handler(void)
	179	{
a0bfa137	180	if (enabled_devices) {
4f86d3a8 LB	181	/* Make sure all changes finished before we switch to new idle */
4f86d3a8 LB	182	smp_wmb();
a0bfa137	183	initialized = 1;
4f86d3a8 LB	184	}
	185	}
	186
	187	/**
	188	* cpuidle_uninstall_idle_handler - uninstalls the cpuidle idle loop handler
	189	*/
	190	void cpuidle_uninstall_idle_handler(void)
	191	{
a0bfa137 LB	192	if (enabled_devices) {
a0bfa137 LB	193	initialized = 0;
4a162513	194	kick_all_cpus_sync();
4f86d3a8 LB	195	}
	196	}
	197
	198	/**
	199	* cpuidle_pause_and_lock - temporarily disables CPUIDLE
	200	*/
	201	void cpuidle_pause_and_lock(void)
	202	{
	203	mutex_lock(&cpuidle_lock);
	204	cpuidle_uninstall_idle_handler();
	205	}
	206
	207	EXPORT_SYMBOL_GPL(cpuidle_pause_and_lock);
	208
	209	/**
	210	* cpuidle_resume_and_unlock - resumes CPUIDLE operation
	211	*/
	212	void cpuidle_resume_and_unlock(void)
	213	{
	214	cpuidle_install_idle_handler();
	215	mutex_unlock(&cpuidle_lock);
	216	}
	217
	218	EXPORT_SYMBOL_GPL(cpuidle_resume_and_unlock);
	219
8651f97b PM	220	/* Currently used in suspend/resume path to suspend cpuidle */
	221	void cpuidle_pause(void)
	222	{
	223	mutex_lock(&cpuidle_lock);
	224	cpuidle_uninstall_idle_handler();
	225	mutex_unlock(&cpuidle_lock);
	226	}
	227
	228	/* Currently used in suspend/resume path to resume cpuidle */
	229	void cpuidle_resume(void)
	230	{
	231	mutex_lock(&cpuidle_lock);
	232	cpuidle_install_idle_handler();
	233	mutex_unlock(&cpuidle_lock);
	234	}
	235
e1689795 RL	236	/**
	237	* cpuidle_wrap_enter - performs timekeeping and irqen around enter function
	238	* @dev: pointer to a valid cpuidle_device object
	239	* @drv: pointer to a valid cpuidle_driver object
	240	* @index: index of the target cpuidle state.
	241	*/
	242	int cpuidle_wrap_enter(struct cpuidle_device *dev,
	243	struct cpuidle_driver *drv, int index,
	244	int (enter)(struct cpuidle_device dev,
	245	struct cpuidle_driver *drv, int index))
	246	{
	247	ktime_t time_start, time_end;
	248	s64 diff;
	249
	250	time_start = ktime_get();
	251
	252	index = enter(dev, drv, index);
	253
	254	time_end = ktime_get();
	255
	256	local_irq_enable();
	257
	258	diff = ktime_to_us(ktime_sub(time_end, time_start));
	259	if (diff > INT_MAX)
	260	diff = INT_MAX;
	261
	262	dev->last_residency = (int) diff;
	263
	264	return index;
	265	}
	266
d8c216cf	267	#ifdef CONFIG_ARCH_HAS_CPU_RELAX
46bcfad7 DD	268	static int poll_idle(struct cpuidle_device *dev,
46bcfad7 DD	269	struct cpuidle_driver *drv, int index)
d8c216cf RW	270	{
	271	ktime_t t1, t2;
	272	s64 diff;
d8c216cf RW	273
	274	t1 = ktime_get();
	275	local_irq_enable();
	276	while (!need_resched())
	277	cpu_relax();
	278
	279	t2 = ktime_get();
	280	diff = ktime_to_us(ktime_sub(t2, t1));
	281	if (diff > INT_MAX)
	282	diff = INT_MAX;
	283
e978aa7d DD	284	dev->last_residency = (int) diff;
	285
	286	return index;
d8c216cf RW	287	}
d8c216cf RW	288
46bcfad7	289	static void poll_idle_init(struct cpuidle_driver *drv)
d8c216cf	290	{
46bcfad7	291	struct cpuidle_state *state = &drv->states[0];
d8c216cf	292
720f1c30	293	snprintf(state->name, CPUIDLE_NAME_LEN, "POLL");
d8c216cf RW	294	snprintf(state->desc, CPUIDLE_DESC_LEN, "CPUIDLE CORE POLL IDLE");
	295	state->exit_latency = 0;
	296	state->target_residency = 0;
	297	state->power_usage = -1;
d247632c	298	state->flags = 0;
d8c216cf	299	state->enter = poll_idle;
cbc9ef02	300	state->disabled = false;
d8c216cf RW	301	}
d8c216cf RW	302	#else
46bcfad7	303	static void poll_idle_init(struct cpuidle_driver *drv) {}
d8c216cf RW	304	#endif /* CONFIG_ARCH_HAS_CPU_RELAX */
d8c216cf RW	305
4f86d3a8 LB	306	/**
	307	* cpuidle_enable_device - enables idle PM for a CPU
	308	* @dev: the CPU
	309	*
	310	* This function must be called between cpuidle_pause_and_lock and
	311	* cpuidle_resume_and_unlock when used externally.
	312	*/
	313	int cpuidle_enable_device(struct cpuidle_device *dev)
	314	{
	315	int ret, i;
bf4d1b5d	316	struct cpuidle_driver *drv;
4f86d3a8	317
1b0a0e9a SB	318	if (!dev)
	319	return -EINVAL;
	320
4f86d3a8 LB	321	if (dev->enabled)
4f86d3a8 LB	322	return 0;
bf4d1b5d DL	323
	324	drv = cpuidle_get_cpu_driver(dev);
	325
e1689795	326	if (!drv \|\| !cpuidle_curr_governor)
4f86d3a8	327	return -EIO;
bf4d1b5d	328
4f86d3a8	329	if (!dev->state_count)
fc850f39	330	dev->state_count = drv->state_count;
4f86d3a8	331
dcb84f33 VP	332	if (dev->registered == 0) {
	333	ret = __cpuidle_register_device(dev);
	334	if (ret)
	335	return ret;
	336	}
	337
e1689795 RL	338	cpuidle_enter_ops = drv->en_core_tk_irqen ?
	339	cpuidle_enter_tk : cpuidle_enter;
	340
	341	poll_idle_init(drv);
d8c216cf	342
bf4d1b5d DL	343	ret = cpuidle_add_device_sysfs(dev);
bf4d1b5d DL	344	if (ret)
4f86d3a8 LB	345	return ret;
	346
	347	if (cpuidle_curr_governor->enable &&
e1689795	348	(ret = cpuidle_curr_governor->enable(drv, dev)))
4f86d3a8 LB	349	goto fail_sysfs;
	350
	351	for (i = 0; i < dev->state_count; i++) {
4202735e DD	352	dev->states_usage[i].usage = 0;
4202735e DD	353	dev->states_usage[i].time = 0;
4f86d3a8 LB	354	}
4f86d3a8 LB	355	dev->last_residency = 0;
4f86d3a8 LB	356
	357	smp_wmb();
	358
	359	dev->enabled = 1;
	360
	361	enabled_devices++;
	362	return 0;
	363
	364	fail_sysfs:
bf4d1b5d	365	cpuidle_remove_device_sysfs(dev);
4f86d3a8 LB	366
	367	return ret;
	368	}
	369
	370	EXPORT_SYMBOL_GPL(cpuidle_enable_device);
	371
	372	/**
	373	* cpuidle_disable_device - disables idle PM for a CPU
	374	* @dev: the CPU
	375	*
	376	* This function must be called between cpuidle_pause_and_lock and
	377	* cpuidle_resume_and_unlock when used externally.
	378	*/
	379	void cpuidle_disable_device(struct cpuidle_device *dev)
	380	{
bf4d1b5d DL	381	struct cpuidle_driver *drv = cpuidle_get_cpu_driver(dev);
bf4d1b5d DL	382
cf31cd1a	383	if (!dev \|\| !dev->enabled)
4f86d3a8	384	return;
bf4d1b5d DL	385
bf4d1b5d DL	386	if (!drv \|\| !cpuidle_curr_governor)
4f86d3a8 LB	387	return;
	388
	389	dev->enabled = 0;
	390
	391	if (cpuidle_curr_governor->disable)
bf4d1b5d	392	cpuidle_curr_governor->disable(drv, dev);
4f86d3a8	393
bf4d1b5d	394	cpuidle_remove_device_sysfs(dev);
4f86d3a8 LB	395	enabled_devices--;
	396	}
	397
	398	EXPORT_SYMBOL_GPL(cpuidle_disable_device);
	399
	400	/**
dcb84f33 VP	401	* __cpuidle_register_device - internal register function called before register
dcb84f33 VP	402	* and enable routines
4f86d3a8	403	* @dev: the cpu
dcb84f33 VP	404	*
dcb84f33 VP	405	* cpuidle_lock mutex must be held before this is called
4f86d3a8	406	*/
dcb84f33	407	static int __cpuidle_register_device(struct cpuidle_device *dev)
4f86d3a8 LB	408	{
4f86d3a8 LB	409	int ret;
bf4d1b5d	410	struct cpuidle_driver *drv = cpuidle_get_cpu_driver(dev);
4f86d3a8	411
bf4d1b5d	412	if (!try_module_get(drv->owner))
4f86d3a8 LB	413	return -EINVAL;
4f86d3a8 LB	414
4f86d3a8 LB	415	per_cpu(cpuidle_devices, dev->cpu) = dev;
4f86d3a8 LB	416	list_add(&dev->device_list, &cpuidle_detected_devices);
1aef40e2	417	ret = cpuidle_add_sysfs(dev);
3af272ab CC	418	if (ret)
3af272ab CC	419	goto err_sysfs;
4f86d3a8	420
4126c019 CC	421	ret = cpuidle_coupled_register_device(dev);
	422	if (ret)
	423	goto err_coupled;
4f86d3a8	424
dcb84f33 VP	425	dev->registered = 1;
dcb84f33 VP	426	return 0;
3af272ab	427
4126c019	428	err_coupled:
1aef40e2	429	cpuidle_remove_sysfs(dev);
3af272ab CC	430	err_sysfs:
	431	list_del(&dev->device_list);
	432	per_cpu(cpuidle_devices, dev->cpu) = NULL;
bf4d1b5d	433	module_put(drv->owner);
3af272ab	434	return ret;
dcb84f33 VP	435	}
	436
	437	/**
	438	* cpuidle_register_device - registers a CPU's idle PM feature
	439	* @dev: the cpu
	440	*/
	441	int cpuidle_register_device(struct cpuidle_device *dev)
	442	{
	443	int ret;
	444
1b0a0e9a SB	445	if (!dev)
	446	return -EINVAL;
	447
dcb84f33 VP	448	mutex_lock(&cpuidle_lock);
	449
	450	if ((ret = __cpuidle_register_device(dev))) {
	451	mutex_unlock(&cpuidle_lock);
	452	return ret;
	453	}
	454
4f86d3a8 LB	455	cpuidle_enable_device(dev);
	456	cpuidle_install_idle_handler();
	457
	458	mutex_unlock(&cpuidle_lock);
	459
	460	return 0;
	461
	462	}
	463
	464	EXPORT_SYMBOL_GPL(cpuidle_register_device);
	465
	466	/**
	467	* cpuidle_unregister_device - unregisters a CPU's idle PM feature
	468	* @dev: the cpu
	469	*/
	470	void cpuidle_unregister_device(struct cpuidle_device *dev)
	471	{
bf4d1b5d	472	struct cpuidle_driver *drv = cpuidle_get_cpu_driver(dev);
4f86d3a8	473
dcb84f33 VP	474	if (dev->registered == 0)
	475	return;
	476
4f86d3a8 LB	477	cpuidle_pause_and_lock();
	478
	479	cpuidle_disable_device(dev);
	480
1aef40e2	481	cpuidle_remove_sysfs(dev);
4f86d3a8	482	list_del(&dev->device_list);
4f86d3a8 LB	483	per_cpu(cpuidle_devices, dev->cpu) = NULL;
4f86d3a8 LB	484
4126c019 CC	485	cpuidle_coupled_unregister_device(dev);
4126c019 CC	486
4f86d3a8 LB	487	cpuidle_resume_and_unlock();
4f86d3a8 LB	488
bf4d1b5d	489	module_put(drv->owner);
4f86d3a8 LB	490	}
	491
	492	EXPORT_SYMBOL_GPL(cpuidle_unregister_device);
	493
	494	#ifdef CONFIG_SMP
	495
	496	static void smp_callback(void *v)
	497	{
	498	/* we already woke the CPU up, nothing more to do */
	499	}
	500
	501	/*
	502	* This function gets called when a part of the kernel has a new latency
	503	* requirement. This means we need to get all processors out of their C-state,
	504	* and then recalculate a new suitable C-state. Just do a cross-cpu IPI; that
	505	* wakes them all right up.
	506	*/
	507	static int cpuidle_latency_notify(struct notifier_block *b,
	508	unsigned long l, void *v)
	509	{
8691e5a8	510	smp_call_function(smp_callback, NULL, 1);
4f86d3a8 LB	511	return NOTIFY_OK;
	512	}
	513
	514	static struct notifier_block cpuidle_latency_notifier = {
	515	.notifier_call = cpuidle_latency_notify,
	516	};
	517
d82b3518 MG	518	static inline void latency_notifier_init(struct notifier_block *n)
	519	{
	520	pm_qos_add_notifier(PM_QOS_CPU_DMA_LATENCY, n);
	521	}
4f86d3a8 LB	522
	523	#else /* CONFIG_SMP */
	524
	525	#define latency_notifier_init(x) do { } while (0)
	526
	527	#endif /* CONFIG_SMP */
	528
	529	/**
	530	* cpuidle_init - core initializer
	531	*/
	532	static int __init cpuidle_init(void)
	533	{
	534	int ret;
	535
62027aea LB	536	if (cpuidle_disabled())
	537	return -ENODEV;
	538
8a25a2fd	539	ret = cpuidle_add_interface(cpu_subsys.dev_root);
4f86d3a8 LB	540	if (ret)
	541	return ret;
	542
	543	latency_notifier_init(&cpuidle_latency_notifier);
	544
	545	return 0;
	546	}
	547
62027aea	548	module_param(off, int, 0444);
4f86d3a8	549	core_initcall(cpuidle_init);