[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/clockchips.h>
#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;

	if (!drv)
		return -ENODEV;

	/* Find lowest-power state that supports long-term idle */
	for (i = drv->state_count - 1; i >= CPUIDLE_DRIVER_STATE_START; i--)
		if (drv->states[i].enter_dead)
			return drv->states[i].enter_dead(dev, i);

	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_cpu_idle_rcuidle(next_state, dev->cpu);

	if (drv->states[next_state].flags & CPUIDLE_FLAG_TIMER_STOP)
		clockevents_notify(CLOCK_EVT_NOTIFY_BROADCAST_ENTER,
				   &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);

	if (drv->states[next_state].flags & CPUIDLE_FLAG_TIMER_STOP)
		clockevents_notify(CLOCK_EVT_NOTIFY_BROADCAST_EXIT,
				   &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
b60e6a0e	11	#include <linux/clockchips.h>
4f86d3a8 LB	12	#include <linux/kernel.h>
	13	#include <linux/mutex.h>
	14	#include <linux/sched.h>
	15	#include <linux/notifier.h>
e8db0be1	16	#include <linux/pm_qos.h>
4f86d3a8 LB	17	#include <linux/cpu.h>
4f86d3a8 LB	18	#include <linux/cpuidle.h>
9a0b8415	19	#include <linux/ktime.h>
2e94d1f7	20	#include <linux/hrtimer.h>
884b17e1	21	#include <linux/module.h>
288f023e	22	#include <trace/events/power.h>
4f86d3a8 LB	23
	24	#include "cpuidle.h"
	25
	26	DEFINE_PER_CPU(struct cpuidle_device *, cpuidle_devices);
4f86d3a8 LB	27
	28	DEFINE_MUTEX(cpuidle_lock);
	29	LIST_HEAD(cpuidle_detected_devices);
4f86d3a8 LB	30
4f86d3a8 LB	31	static int enabled_devices;
62027aea	32	static int off __read_mostly;
a0bfa137	33	static int initialized __read_mostly;
62027aea LB	34
	35	int cpuidle_disabled(void)
	36	{
	37	return off;
	38	}
d91ee586 LB	39	void disable_cpuidle(void)
	40	{
	41	off = 1;
	42	}
4f86d3a8	43
dcb84f33 VP	44	static int __cpuidle_register_device(struct cpuidle_device *dev);
dcb84f33 VP	45
e1689795 RL	46	static inline int cpuidle_enter(struct cpuidle_device *dev,
	47	struct cpuidle_driver *drv, int index)
	48	{
	49	struct cpuidle_state *target_state = &drv->states[index];
	50	return target_state->enter(dev, drv, index);
	51	}
	52
	53	static inline int cpuidle_enter_tk(struct cpuidle_device *dev,
	54	struct cpuidle_driver *drv, int index)
	55	{
	56	return cpuidle_wrap_enter(dev, drv, index, cpuidle_enter);
	57	}
	58
	59	typedef int (cpuidle_enter_t)(struct cpuidle_device dev,
	60	struct cpuidle_driver *drv, int index);
	61
	62	static cpuidle_enter_t cpuidle_enter_ops;
	63
1a022e3f BO	64	/**
	65	* cpuidle_play_dead - cpu off-lining
	66	*
ee01e663	67	* Returns in case of an error or no driver
1a022e3f BO	68	*/
	69	int cpuidle_play_dead(void)
	70	{
	71	struct cpuidle_device *dev = __this_cpu_read(cpuidle_devices);
bf4d1b5d	72	struct cpuidle_driver *drv = cpuidle_get_cpu_driver(dev);
8aef33a7	73	int i;
1a022e3f	74
ee01e663 TK	75	if (!drv)
	76	return -ENODEV;
	77
1a022e3f	78	/* Find lowest-power state that supports long-term idle */
8aef33a7 DL	79	for (i = drv->state_count - 1; i >= CPUIDLE_DRIVER_STATE_START; i--)
	80	if (drv->states[i].enter_dead)
	81	return drv->states[i].enter_dead(dev, i);
1a022e3f BO	82
	83	return -ENODEV;
	84	}
	85
56cfbf74 CC	86	/**
	87	* cpuidle_enter_state - enter the state and update stats
	88	* @dev: cpuidle device for this cpu
	89	* @drv: cpuidle driver for this cpu
	90	* @next_state: index into drv->states of the state to enter
	91	*/
	92	int cpuidle_enter_state(struct cpuidle_device dev, struct cpuidle_driver drv,
	93	int next_state)
	94	{
	95	int entered_state;
	96
	97	entered_state = cpuidle_enter_ops(dev, drv, next_state);
	98
	99	if (entered_state >= 0) {
	100	/* Update cpuidle counters */
	101	/* This can be moved to within driver enter routine
	102	* but that results in multiple copies of same code.
	103	*/
a474a515	104	dev->states_usage[entered_state].time += dev->last_residency;
56cfbf74 CC	105	dev->states_usage[entered_state].usage++;
	106	} else {
	107	dev->last_residency = 0;
	108	}
	109
	110	return entered_state;
	111	}
	112
4f86d3a8 LB	113	/**
	114	* cpuidle_idle_call - the main idle loop
	115	*
	116	* NOTE: no locks or semaphores should be used here
a0bfa137	117	* return non-zero on failure
4f86d3a8	118	*/
a0bfa137	119	int cpuidle_idle_call(void)
4f86d3a8	120	{
4a6f4fe8	121	struct cpuidle_device *dev = __this_cpu_read(cpuidle_devices);
bf4d1b5d	122	struct cpuidle_driver *drv;
e978aa7d	123	int next_state, entered_state;
4f86d3a8	124
a0bfa137 LB	125	if (off)
	126	return -ENODEV;
	127
	128	if (!initialized)
	129	return -ENODEV;
	130
4f86d3a8	131	/* check if the device is ready */
a0bfa137 LB	132	if (!dev \|\| !dev->enabled)
a0bfa137 LB	133	return -EBUSY;
4f86d3a8	134
bf4d1b5d DL	135	drv = cpuidle_get_cpu_driver(dev);
bf4d1b5d DL	136
4f86d3a8	137	/* ask the governor for the next state */
46bcfad7	138	next_state = cpuidle_curr_governor->select(drv, dev);
246eb7f0	139	if (need_resched()) {
d73d68dc YS	140	dev->last_residency = 0;
	141	/* give the governor an opportunity to reflect on the outcome */
	142	if (cpuidle_curr_governor->reflect)
	143	cpuidle_curr_governor->reflect(dev, next_state);
246eb7f0	144	local_irq_enable();
a0bfa137	145	return 0;
246eb7f0 KH	146	}
246eb7f0 KH	147
76027ea8	148	trace_cpu_idle_rcuidle(next_state, dev->cpu);
f77cfe4e	149
b60e6a0e DL	150	if (drv->states[next_state].flags & CPUIDLE_FLAG_TIMER_STOP)
	151	clockevents_notify(CLOCK_EVT_NOTIFY_BROADCAST_ENTER,
	152	&dev->cpu);
	153
4126c019 CC	154	if (cpuidle_state_is_coupled(dev, drv, next_state))
	155	entered_state = cpuidle_enter_state_coupled(dev, drv,
	156	next_state);
	157	else
	158	entered_state = cpuidle_enter_state(dev, drv, next_state);
f77cfe4e	159
b60e6a0e DL	160	if (drv->states[next_state].flags & CPUIDLE_FLAG_TIMER_STOP)
	161	clockevents_notify(CLOCK_EVT_NOTIFY_BROADCAST_EXIT,
	162	&dev->cpu);
	163
76027ea8	164	trace_cpu_idle_rcuidle(PWR_EVENT_EXIT, dev->cpu);
f77cfe4e	165
4f86d3a8 LB	166	/* give the governor an opportunity to reflect on the outcome */
4f86d3a8 LB	167	if (cpuidle_curr_governor->reflect)
e978aa7d	168	cpuidle_curr_governor->reflect(dev, entered_state);
a0bfa137 LB	169
a0bfa137 LB	170	return 0;
4f86d3a8 LB	171	}
	172
	173	/**
	174	* cpuidle_install_idle_handler - installs the cpuidle idle loop handler
	175	*/
	176	void cpuidle_install_idle_handler(void)
	177	{
a0bfa137	178	if (enabled_devices) {
4f86d3a8 LB	179	/* Make sure all changes finished before we switch to new idle */
4f86d3a8 LB	180	smp_wmb();
a0bfa137	181	initialized = 1;
4f86d3a8 LB	182	}
	183	}
	184
	185	/**
	186	* cpuidle_uninstall_idle_handler - uninstalls the cpuidle idle loop handler
	187	*/
	188	void cpuidle_uninstall_idle_handler(void)
	189	{
a0bfa137 LB	190	if (enabled_devices) {
a0bfa137 LB	191	initialized = 0;
4a162513	192	kick_all_cpus_sync();
4f86d3a8 LB	193	}
	194	}
	195
	196	/**
	197	* cpuidle_pause_and_lock - temporarily disables CPUIDLE
	198	*/
	199	void cpuidle_pause_and_lock(void)
	200	{
	201	mutex_lock(&cpuidle_lock);
	202	cpuidle_uninstall_idle_handler();
	203	}
	204
	205	EXPORT_SYMBOL_GPL(cpuidle_pause_and_lock);
	206
	207	/**
	208	* cpuidle_resume_and_unlock - resumes CPUIDLE operation
	209	*/
	210	void cpuidle_resume_and_unlock(void)
	211	{
	212	cpuidle_install_idle_handler();
	213	mutex_unlock(&cpuidle_lock);
	214	}
	215
	216	EXPORT_SYMBOL_GPL(cpuidle_resume_and_unlock);
	217
8651f97b PM	218	/* Currently used in suspend/resume path to suspend cpuidle */
	219	void cpuidle_pause(void)
	220	{
	221	mutex_lock(&cpuidle_lock);
	222	cpuidle_uninstall_idle_handler();
	223	mutex_unlock(&cpuidle_lock);
	224	}
	225
	226	/* Currently used in suspend/resume path to resume cpuidle */
	227	void cpuidle_resume(void)
	228	{
	229	mutex_lock(&cpuidle_lock);
	230	cpuidle_install_idle_handler();
	231	mutex_unlock(&cpuidle_lock);
	232	}
	233
e1689795 RL	234	/**
	235	* cpuidle_wrap_enter - performs timekeeping and irqen around enter function
	236	* @dev: pointer to a valid cpuidle_device object
	237	* @drv: pointer to a valid cpuidle_driver object
	238	* @index: index of the target cpuidle state.
	239	*/
	240	int cpuidle_wrap_enter(struct cpuidle_device *dev,
	241	struct cpuidle_driver *drv, int index,
	242	int (enter)(struct cpuidle_device dev,
	243	struct cpuidle_driver *drv, int index))
	244	{
	245	ktime_t time_start, time_end;
	246	s64 diff;
	247
	248	time_start = ktime_get();
	249
	250	index = enter(dev, drv, index);
	251
	252	time_end = ktime_get();
	253
	254	local_irq_enable();
	255
	256	diff = ktime_to_us(ktime_sub(time_end, time_start));
	257	if (diff > INT_MAX)
	258	diff = INT_MAX;
	259
	260	dev->last_residency = (int) diff;
	261
	262	return index;
	263	}
	264
d8c216cf	265	#ifdef CONFIG_ARCH_HAS_CPU_RELAX
46bcfad7 DD	266	static int poll_idle(struct cpuidle_device *dev,
46bcfad7 DD	267	struct cpuidle_driver *drv, int index)
d8c216cf RW	268	{
	269	ktime_t t1, t2;
	270	s64 diff;
d8c216cf RW	271
	272	t1 = ktime_get();
	273	local_irq_enable();
	274	while (!need_resched())
	275	cpu_relax();
	276
	277	t2 = ktime_get();
	278	diff = ktime_to_us(ktime_sub(t2, t1));
	279	if (diff > INT_MAX)
	280	diff = INT_MAX;
	281
e978aa7d DD	282	dev->last_residency = (int) diff;
	283
	284	return index;
d8c216cf RW	285	}
d8c216cf RW	286
46bcfad7	287	static void poll_idle_init(struct cpuidle_driver *drv)
d8c216cf	288	{
46bcfad7	289	struct cpuidle_state *state = &drv->states[0];
d8c216cf	290
720f1c30	291	snprintf(state->name, CPUIDLE_NAME_LEN, "POLL");
d8c216cf RW	292	snprintf(state->desc, CPUIDLE_DESC_LEN, "CPUIDLE CORE POLL IDLE");
	293	state->exit_latency = 0;
	294	state->target_residency = 0;
	295	state->power_usage = -1;
d247632c	296	state->flags = 0;
d8c216cf	297	state->enter = poll_idle;
cbc9ef02	298	state->disabled = false;
d8c216cf RW	299	}
d8c216cf RW	300	#else
46bcfad7	301	static void poll_idle_init(struct cpuidle_driver *drv) {}
d8c216cf RW	302	#endif /* CONFIG_ARCH_HAS_CPU_RELAX */
d8c216cf RW	303
4f86d3a8 LB	304	/**
	305	* cpuidle_enable_device - enables idle PM for a CPU
	306	* @dev: the CPU
	307	*
	308	* This function must be called between cpuidle_pause_and_lock and
	309	* cpuidle_resume_and_unlock when used externally.
	310	*/
	311	int cpuidle_enable_device(struct cpuidle_device *dev)
	312	{
	313	int ret, i;
bf4d1b5d	314	struct cpuidle_driver *drv;
4f86d3a8	315
1b0a0e9a SB	316	if (!dev)
	317	return -EINVAL;
	318
4f86d3a8 LB	319	if (dev->enabled)
4f86d3a8 LB	320	return 0;
bf4d1b5d DL	321
	322	drv = cpuidle_get_cpu_driver(dev);
	323
e1689795	324	if (!drv \|\| !cpuidle_curr_governor)
4f86d3a8	325	return -EIO;
bf4d1b5d	326
4f86d3a8	327	if (!dev->state_count)
fc850f39	328	dev->state_count = drv->state_count;
4f86d3a8	329
dcb84f33 VP	330	if (dev->registered == 0) {
	331	ret = __cpuidle_register_device(dev);
	332	if (ret)
	333	return ret;
	334	}
	335
e1689795 RL	336	cpuidle_enter_ops = drv->en_core_tk_irqen ?
	337	cpuidle_enter_tk : cpuidle_enter;
	338
	339	poll_idle_init(drv);
d8c216cf	340
bf4d1b5d DL	341	ret = cpuidle_add_device_sysfs(dev);
bf4d1b5d DL	342	if (ret)
4f86d3a8 LB	343	return ret;
	344
	345	if (cpuidle_curr_governor->enable &&
e1689795	346	(ret = cpuidle_curr_governor->enable(drv, dev)))
4f86d3a8 LB	347	goto fail_sysfs;
	348
	349	for (i = 0; i < dev->state_count; i++) {
4202735e DD	350	dev->states_usage[i].usage = 0;
4202735e DD	351	dev->states_usage[i].time = 0;
4f86d3a8 LB	352	}
4f86d3a8 LB	353	dev->last_residency = 0;
4f86d3a8 LB	354
	355	smp_wmb();
	356
	357	dev->enabled = 1;
	358
	359	enabled_devices++;
	360	return 0;
	361
	362	fail_sysfs:
bf4d1b5d	363	cpuidle_remove_device_sysfs(dev);
4f86d3a8 LB	364
	365	return ret;
	366	}
	367
	368	EXPORT_SYMBOL_GPL(cpuidle_enable_device);
	369
	370	/**
	371	* cpuidle_disable_device - disables idle PM for a CPU
	372	* @dev: the CPU
	373	*
	374	* This function must be called between cpuidle_pause_and_lock and
	375	* cpuidle_resume_and_unlock when used externally.
	376	*/
	377	void cpuidle_disable_device(struct cpuidle_device *dev)
	378	{
bf4d1b5d DL	379	struct cpuidle_driver *drv = cpuidle_get_cpu_driver(dev);
bf4d1b5d DL	380
cf31cd1a	381	if (!dev \|\| !dev->enabled)
4f86d3a8	382	return;
bf4d1b5d DL	383
bf4d1b5d DL	384	if (!drv \|\| !cpuidle_curr_governor)
4f86d3a8 LB	385	return;
	386
	387	dev->enabled = 0;
	388
	389	if (cpuidle_curr_governor->disable)
bf4d1b5d	390	cpuidle_curr_governor->disable(drv, dev);
4f86d3a8	391
bf4d1b5d	392	cpuidle_remove_device_sysfs(dev);
4f86d3a8 LB	393	enabled_devices--;
	394	}
	395
	396	EXPORT_SYMBOL_GPL(cpuidle_disable_device);
	397
	398	/**
dcb84f33 VP	399	* __cpuidle_register_device - internal register function called before register
dcb84f33 VP	400	* and enable routines
4f86d3a8	401	* @dev: the cpu
dcb84f33 VP	402	*
dcb84f33 VP	403	* cpuidle_lock mutex must be held before this is called
4f86d3a8	404	*/
dcb84f33	405	static int __cpuidle_register_device(struct cpuidle_device *dev)
4f86d3a8 LB	406	{
4f86d3a8 LB	407	int ret;
bf4d1b5d	408	struct cpuidle_driver *drv = cpuidle_get_cpu_driver(dev);
4f86d3a8	409
bf4d1b5d	410	if (!try_module_get(drv->owner))
4f86d3a8 LB	411	return -EINVAL;
4f86d3a8 LB	412
4f86d3a8 LB	413	per_cpu(cpuidle_devices, dev->cpu) = dev;
4f86d3a8 LB	414	list_add(&dev->device_list, &cpuidle_detected_devices);
1aef40e2	415	ret = cpuidle_add_sysfs(dev);
3af272ab CC	416	if (ret)
3af272ab CC	417	goto err_sysfs;
4f86d3a8	418
4126c019 CC	419	ret = cpuidle_coupled_register_device(dev);
	420	if (ret)
	421	goto err_coupled;
4f86d3a8	422
dcb84f33 VP	423	dev->registered = 1;
dcb84f33 VP	424	return 0;
3af272ab	425
4126c019	426	err_coupled:
1aef40e2	427	cpuidle_remove_sysfs(dev);
3af272ab CC	428	err_sysfs:
	429	list_del(&dev->device_list);
	430	per_cpu(cpuidle_devices, dev->cpu) = NULL;
bf4d1b5d	431	module_put(drv->owner);
3af272ab	432	return ret;
dcb84f33 VP	433	}
	434
	435	/**
	436	* cpuidle_register_device - registers a CPU's idle PM feature
	437	* @dev: the cpu
	438	*/
	439	int cpuidle_register_device(struct cpuidle_device *dev)
	440	{
	441	int ret;
	442
1b0a0e9a SB	443	if (!dev)
	444	return -EINVAL;
	445
dcb84f33 VP	446	mutex_lock(&cpuidle_lock);
	447
	448	if ((ret = __cpuidle_register_device(dev))) {
	449	mutex_unlock(&cpuidle_lock);
	450	return ret;
	451	}
	452
4f86d3a8 LB	453	cpuidle_enable_device(dev);
	454	cpuidle_install_idle_handler();
	455
	456	mutex_unlock(&cpuidle_lock);
	457
	458	return 0;
	459
	460	}
	461
	462	EXPORT_SYMBOL_GPL(cpuidle_register_device);
	463
	464	/**
	465	* cpuidle_unregister_device - unregisters a CPU's idle PM feature
	466	* @dev: the cpu
	467	*/
	468	void cpuidle_unregister_device(struct cpuidle_device *dev)
	469	{
bf4d1b5d	470	struct cpuidle_driver *drv = cpuidle_get_cpu_driver(dev);
4f86d3a8	471
dcb84f33 VP	472	if (dev->registered == 0)
	473	return;
	474
4f86d3a8 LB	475	cpuidle_pause_and_lock();
	476
	477	cpuidle_disable_device(dev);
	478
1aef40e2	479	cpuidle_remove_sysfs(dev);
4f86d3a8	480	list_del(&dev->device_list);
4f86d3a8 LB	481	per_cpu(cpuidle_devices, dev->cpu) = NULL;
4f86d3a8 LB	482
4126c019 CC	483	cpuidle_coupled_unregister_device(dev);
4126c019 CC	484
4f86d3a8 LB	485	cpuidle_resume_and_unlock();
4f86d3a8 LB	486
bf4d1b5d	487	module_put(drv->owner);
4f86d3a8 LB	488	}
	489
	490	EXPORT_SYMBOL_GPL(cpuidle_unregister_device);
	491
	492	#ifdef CONFIG_SMP
	493
	494	static void smp_callback(void *v)
	495	{
	496	/* we already woke the CPU up, nothing more to do */
	497	}
	498
	499	/*
	500	* This function gets called when a part of the kernel has a new latency
	501	* requirement. This means we need to get all processors out of their C-state,
	502	* and then recalculate a new suitable C-state. Just do a cross-cpu IPI; that
	503	* wakes them all right up.
	504	*/
	505	static int cpuidle_latency_notify(struct notifier_block *b,
	506	unsigned long l, void *v)
	507	{
8691e5a8	508	smp_call_function(smp_callback, NULL, 1);
4f86d3a8 LB	509	return NOTIFY_OK;
	510	}
	511
	512	static struct notifier_block cpuidle_latency_notifier = {
	513	.notifier_call = cpuidle_latency_notify,
	514	};
	515
d82b3518 MG	516	static inline void latency_notifier_init(struct notifier_block *n)
	517	{
	518	pm_qos_add_notifier(PM_QOS_CPU_DMA_LATENCY, n);
	519	}
4f86d3a8 LB	520
	521	#else /* CONFIG_SMP */
	522
	523	#define latency_notifier_init(x) do { } while (0)
	524
	525	#endif /* CONFIG_SMP */
	526
	527	/**
	528	* cpuidle_init - core initializer
	529	*/
	530	static int __init cpuidle_init(void)
	531	{
	532	int ret;
	533
62027aea LB	534	if (cpuidle_disabled())
	535	return -ENODEV;
	536
8a25a2fd	537	ret = cpuidle_add_interface(cpu_subsys.dev_root);
4f86d3a8 LB	538	if (ret)
	539	return ret;
	540
	541	latency_notifier_init(&cpuidle_latency_notifier);
	542
	543	return 0;
	544	}
	545
62027aea	546	module_param(off, int, 0444);
4f86d3a8	547	core_initcall(cpuidle_init);