[mirror_ubuntu-bionic-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/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_PER_CPU(struct cpuidle_device, cpuidle_dev);

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);

/**
 * 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 index)
{
	int entered_state;

	struct cpuidle_state *target_state = &drv->states[index];
	ktime_t time_start, time_end;
	s64 diff;

	time_start = ktime_get();

	entered_state = target_state->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;

	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);
}

#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->registered)
		return -EINVAL;

	if (!dev->state_count)
		dev->state_count = drv->state_count;

	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;
	}

	ret = cpuidle_enable_device(dev);
	if (ret) {
		mutex_unlock(&cpuidle_lock);
		return ret;
	}

	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);

/**
 * cpuidle_unregister: unregister a driver and the devices. This function
 * can be used only if the driver has been previously registered through
 * the cpuidle_register function.
 *
 * @drv: a valid pointer to a struct cpuidle_driver
 */
void cpuidle_unregister(struct cpuidle_driver *drv)
{
	int cpu;
	struct cpuidle_device *device;

	for_each_cpu(cpu, drv->cpumask) {
		device = &per_cpu(cpuidle_dev, cpu);
		cpuidle_unregister_device(device);
	}

	cpuidle_unregister_driver(drv);
}
EXPORT_SYMBOL_GPL(cpuidle_unregister);

/**
 * cpuidle_register: registers the driver and the cpu devices with the
 * coupled_cpus passed as parameter. This function is used for all common
 * initialization pattern there are in the arch specific drivers. The
 * devices is globally defined in this file.
 *
 * @drv         : a valid pointer to a struct cpuidle_driver
 * @coupled_cpus: a cpumask for the coupled states
 *
 * Returns 0 on success, < 0 otherwise
 */
int cpuidle_register(struct cpuidle_driver *drv,
		     const struct cpumask *const coupled_cpus)
{
	int ret, cpu;
	struct cpuidle_device *device;

	ret = cpuidle_register_driver(drv);
	if (ret) {
		pr_err("failed to register cpuidle driver\n");
		return ret;
	}

	for_each_cpu(cpu, drv->cpumask) {
		device = &per_cpu(cpuidle_dev, cpu);
		device->cpu = cpu;

#ifdef CONFIG_ARCH_NEEDS_CPU_IDLE_COUPLED
		/*
		 * On multiplatform for ARM, the coupled idle states could
		 * enabled in the kernel even if the cpuidle driver does not
		 * use it. Note, coupled_cpus is a struct copy.
		 */
		if (coupled_cpus)
			device->coupled_cpus = *coupled_cpus;
#endif
		ret = cpuidle_register_device(device);
		if (!ret)
			continue;

		pr_err("Failed to register cpuidle device for cpu%d\n", cpu);

		cpuidle_unregister(drv);
		break;
	}

	return ret;
}
EXPORT_SYMBOL_GPL(cpuidle_register);

#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
	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/clockchips.h>
	12	#include <linux/kernel.h>
	13	#include <linux/mutex.h>
	14	#include <linux/sched.h>
	15	#include <linux/notifier.h>
	16	#include <linux/pm_qos.h>
	17	#include <linux/cpu.h>
	18	#include <linux/cpuidle.h>
	19	#include <linux/ktime.h>
	20	#include <linux/hrtimer.h>
	21	#include <linux/module.h>
	22	#include <trace/events/power.h>
	23
	24	#include "cpuidle.h"
	25
	26	DEFINE_PER_CPU(struct cpuidle_device *, cpuidle_devices);
	27	DEFINE_PER_CPU(struct cpuidle_device, cpuidle_dev);
	28
	29	DEFINE_MUTEX(cpuidle_lock);
	30	LIST_HEAD(cpuidle_detected_devices);
	31
	32	static int enabled_devices;
	33	static int off __read_mostly;
	34	static int initialized __read_mostly;
	35
	36	int cpuidle_disabled(void)
	37	{
	38	return off;
	39	}
	40	void disable_cpuidle(void)
	41	{
	42	off = 1;
	43	}
	44
	45	static int __cpuidle_register_device(struct cpuidle_device *dev);
	46
	47	/**
	48	* cpuidle_play_dead - cpu off-lining
	49	*
	50	* Returns in case of an error or no driver
	51	*/
	52	int cpuidle_play_dead(void)
	53	{
	54	struct cpuidle_device *dev = __this_cpu_read(cpuidle_devices);
	55	struct cpuidle_driver *drv = cpuidle_get_cpu_driver(dev);
	56	int i;
	57
	58	if (!drv)
	59	return -ENODEV;
	60
	61	/* Find lowest-power state that supports long-term idle */
	62	for (i = drv->state_count - 1; i >= CPUIDLE_DRIVER_STATE_START; i--)
	63	if (drv->states[i].enter_dead)
	64	return drv->states[i].enter_dead(dev, i);
	65
	66	return -ENODEV;
	67	}
	68
	69	/**
	70	* cpuidle_enter_state - enter the state and update stats
	71	* @dev: cpuidle device for this cpu
	72	* @drv: cpuidle driver for this cpu
	73	* @next_state: index into drv->states of the state to enter
	74	*/
	75	int cpuidle_enter_state(struct cpuidle_device dev, struct cpuidle_driver drv,
	76	int index)
	77	{
	78	int entered_state;
	79
	80	struct cpuidle_state *target_state = &drv->states[index];
	81	ktime_t time_start, time_end;
	82	s64 diff;
	83
	84	time_start = ktime_get();
	85
	86	entered_state = target_state->enter(dev, drv, index);
	87
	88	time_end = ktime_get();
	89
	90	local_irq_enable();
	91
	92	diff = ktime_to_us(ktime_sub(time_end, time_start));
	93	if (diff > INT_MAX)
	94	diff = INT_MAX;
	95
	96	dev->last_residency = (int) diff;
	97
	98	if (entered_state >= 0) {
	99	/* Update cpuidle counters */
	100	/* This can be moved to within driver enter routine
	101	* but that results in multiple copies of same code.
	102	*/
	103	dev->states_usage[entered_state].time += dev->last_residency;
	104	dev->states_usage[entered_state].usage++;
	105	} else {
	106	dev->last_residency = 0;
	107	}
	108
	109	return entered_state;
	110	}
	111
	112	/**
	113	* cpuidle_idle_call - the main idle loop
	114	*
	115	* NOTE: no locks or semaphores should be used here
	116	* return non-zero on failure
	117	*/
	118	int cpuidle_idle_call(void)
	119	{
	120	struct cpuidle_device *dev = __this_cpu_read(cpuidle_devices);
	121	struct cpuidle_driver *drv;
	122	int next_state, entered_state;
	123
	124	if (off)
	125	return -ENODEV;
	126
	127	if (!initialized)
	128	return -ENODEV;
	129
	130	/* check if the device is ready */
	131	if (!dev \|\| !dev->enabled)
	132	return -EBUSY;
	133
	134	drv = cpuidle_get_cpu_driver(dev);
	135
	136	/* ask the governor for the next state */
	137	next_state = cpuidle_curr_governor->select(drv, dev);
	138	if (need_resched()) {
	139	dev->last_residency = 0;
	140	/* give the governor an opportunity to reflect on the outcome */
	141	if (cpuidle_curr_governor->reflect)
	142	cpuidle_curr_governor->reflect(dev, next_state);
	143	local_irq_enable();
	144	return 0;
	145	}
	146
	147	trace_cpu_idle_rcuidle(next_state, dev->cpu);
	148
	149	if (drv->states[next_state].flags & CPUIDLE_FLAG_TIMER_STOP)
	150	clockevents_notify(CLOCK_EVT_NOTIFY_BROADCAST_ENTER,
	151	&dev->cpu);
	152
	153	if (cpuidle_state_is_coupled(dev, drv, next_state))
	154	entered_state = cpuidle_enter_state_coupled(dev, drv,
	155	next_state);
	156	else
	157	entered_state = cpuidle_enter_state(dev, drv, next_state);
	158
	159	if (drv->states[next_state].flags & CPUIDLE_FLAG_TIMER_STOP)
	160	clockevents_notify(CLOCK_EVT_NOTIFY_BROADCAST_EXIT,
	161	&dev->cpu);
	162
	163	trace_cpu_idle_rcuidle(PWR_EVENT_EXIT, dev->cpu);
	164
	165	/* give the governor an opportunity to reflect on the outcome */
	166	if (cpuidle_curr_governor->reflect)
	167	cpuidle_curr_governor->reflect(dev, entered_state);
	168
	169	return 0;
	170	}
	171
	172	/**
	173	* cpuidle_install_idle_handler - installs the cpuidle idle loop handler
	174	*/
	175	void cpuidle_install_idle_handler(void)
	176	{
	177	if (enabled_devices) {
	178	/* Make sure all changes finished before we switch to new idle */
	179	smp_wmb();
	180	initialized = 1;
	181	}
	182	}
	183
	184	/**
	185	* cpuidle_uninstall_idle_handler - uninstalls the cpuidle idle loop handler
	186	*/
	187	void cpuidle_uninstall_idle_handler(void)
	188	{
	189	if (enabled_devices) {
	190	initialized = 0;
	191	kick_all_cpus_sync();
	192	}
	193	}
	194
	195	/**
	196	* cpuidle_pause_and_lock - temporarily disables CPUIDLE
	197	*/
	198	void cpuidle_pause_and_lock(void)
	199	{
	200	mutex_lock(&cpuidle_lock);
	201	cpuidle_uninstall_idle_handler();
	202	}
	203
	204	EXPORT_SYMBOL_GPL(cpuidle_pause_and_lock);
	205
	206	/**
	207	* cpuidle_resume_and_unlock - resumes CPUIDLE operation
	208	*/
	209	void cpuidle_resume_and_unlock(void)
	210	{
	211	cpuidle_install_idle_handler();
	212	mutex_unlock(&cpuidle_lock);
	213	}
	214
	215	EXPORT_SYMBOL_GPL(cpuidle_resume_and_unlock);
	216
	217	/* Currently used in suspend/resume path to suspend cpuidle */
	218	void cpuidle_pause(void)
	219	{
	220	mutex_lock(&cpuidle_lock);
	221	cpuidle_uninstall_idle_handler();
	222	mutex_unlock(&cpuidle_lock);
	223	}
	224
	225	/* Currently used in suspend/resume path to resume cpuidle */
	226	void cpuidle_resume(void)
	227	{
	228	mutex_lock(&cpuidle_lock);
	229	cpuidle_install_idle_handler();
	230	mutex_unlock(&cpuidle_lock);
	231	}
	232
	233	#ifdef CONFIG_ARCH_HAS_CPU_RELAX
	234	static int poll_idle(struct cpuidle_device *dev,
	235	struct cpuidle_driver *drv, int index)
	236	{
	237	ktime_t t1, t2;
	238	s64 diff;
	239
	240	t1 = ktime_get();
	241	local_irq_enable();
	242	while (!need_resched())
	243	cpu_relax();
	244
	245	t2 = ktime_get();
	246	diff = ktime_to_us(ktime_sub(t2, t1));
	247	if (diff > INT_MAX)
	248	diff = INT_MAX;
	249
	250	dev->last_residency = (int) diff;
	251
	252	return index;
	253	}
	254
	255	static void poll_idle_init(struct cpuidle_driver *drv)
	256	{
	257	struct cpuidle_state *state = &drv->states[0];
	258
	259	snprintf(state->name, CPUIDLE_NAME_LEN, "POLL");
	260	snprintf(state->desc, CPUIDLE_DESC_LEN, "CPUIDLE CORE POLL IDLE");
	261	state->exit_latency = 0;
	262	state->target_residency = 0;
	263	state->power_usage = -1;
	264	state->flags = 0;
	265	state->enter = poll_idle;
	266	state->disabled = false;
	267	}
	268	#else
	269	static void poll_idle_init(struct cpuidle_driver *drv) {}
	270	#endif /* CONFIG_ARCH_HAS_CPU_RELAX */
	271
	272	/**
	273	* cpuidle_enable_device - enables idle PM for a CPU
	274	* @dev: the CPU
	275	*
	276	* This function must be called between cpuidle_pause_and_lock and
	277	* cpuidle_resume_and_unlock when used externally.
	278	*/
	279	int cpuidle_enable_device(struct cpuidle_device *dev)
	280	{
	281	int ret, i;
	282	struct cpuidle_driver *drv;
	283
	284	if (!dev)
	285	return -EINVAL;
	286
	287	if (dev->enabled)
	288	return 0;
	289
	290	drv = cpuidle_get_cpu_driver(dev);
	291
	292	if (!drv \|\| !cpuidle_curr_governor)
	293	return -EIO;
	294
	295	if (!dev->registered)
	296	return -EINVAL;
	297
	298	if (!dev->state_count)
	299	dev->state_count = drv->state_count;
	300
	301	poll_idle_init(drv);
	302
	303	ret = cpuidle_add_device_sysfs(dev);
	304	if (ret)
	305	return ret;
	306
	307	if (cpuidle_curr_governor->enable &&
	308	(ret = cpuidle_curr_governor->enable(drv, dev)))
	309	goto fail_sysfs;
	310
	311	for (i = 0; i < dev->state_count; i++) {
	312	dev->states_usage[i].usage = 0;
	313	dev->states_usage[i].time = 0;
	314	}
	315	dev->last_residency = 0;
	316
	317	smp_wmb();
	318
	319	dev->enabled = 1;
	320
	321	enabled_devices++;
	322	return 0;
	323
	324	fail_sysfs:
	325	cpuidle_remove_device_sysfs(dev);
	326
	327	return ret;
	328	}
	329
	330	EXPORT_SYMBOL_GPL(cpuidle_enable_device);
	331
	332	/**
	333	* cpuidle_disable_device - disables idle PM for a CPU
	334	* @dev: the CPU
	335	*
	336	* This function must be called between cpuidle_pause_and_lock and
	337	* cpuidle_resume_and_unlock when used externally.
	338	*/
	339	void cpuidle_disable_device(struct cpuidle_device *dev)
	340	{
	341	struct cpuidle_driver *drv = cpuidle_get_cpu_driver(dev);
	342
	343	if (!dev \|\| !dev->enabled)
	344	return;
	345
	346	if (!drv \|\| !cpuidle_curr_governor)
	347	return;
	348
	349	dev->enabled = 0;
	350
	351	if (cpuidle_curr_governor->disable)
	352	cpuidle_curr_governor->disable(drv, dev);
	353
	354	cpuidle_remove_device_sysfs(dev);
	355	enabled_devices--;
	356	}
	357
	358	EXPORT_SYMBOL_GPL(cpuidle_disable_device);
	359
	360	/**
	361	* __cpuidle_register_device - internal register function called before register
	362	* and enable routines
	363	* @dev: the cpu
	364	*
	365	* cpuidle_lock mutex must be held before this is called
	366	*/
	367	static int __cpuidle_register_device(struct cpuidle_device *dev)
	368	{
	369	int ret;
	370	struct cpuidle_driver *drv = cpuidle_get_cpu_driver(dev);
	371
	372	if (!try_module_get(drv->owner))
	373	return -EINVAL;
	374
	375	per_cpu(cpuidle_devices, dev->cpu) = dev;
	376	list_add(&dev->device_list, &cpuidle_detected_devices);
	377	ret = cpuidle_add_sysfs(dev);
	378	if (ret)
	379	goto err_sysfs;
	380
	381	ret = cpuidle_coupled_register_device(dev);
	382	if (ret)
	383	goto err_coupled;
	384
	385	dev->registered = 1;
	386	return 0;
	387
	388	err_coupled:
	389	cpuidle_remove_sysfs(dev);
	390	err_sysfs:
	391	list_del(&dev->device_list);
	392	per_cpu(cpuidle_devices, dev->cpu) = NULL;
	393	module_put(drv->owner);
	394	return ret;
	395	}
	396
	397	/**
	398	* cpuidle_register_device - registers a CPU's idle PM feature
	399	* @dev: the cpu
	400	*/
	401	int cpuidle_register_device(struct cpuidle_device *dev)
	402	{
	403	int ret;
	404
	405	if (!dev)
	406	return -EINVAL;
	407
	408	mutex_lock(&cpuidle_lock);
	409
	410	if ((ret = __cpuidle_register_device(dev))) {
	411	mutex_unlock(&cpuidle_lock);
	412	return ret;
	413	}
	414
	415	ret = cpuidle_enable_device(dev);
	416	if (ret) {
	417	mutex_unlock(&cpuidle_lock);
	418	return ret;
	419	}
	420
	421	cpuidle_install_idle_handler();
	422
	423	mutex_unlock(&cpuidle_lock);
	424
	425	return 0;
	426	}
	427
	428	EXPORT_SYMBOL_GPL(cpuidle_register_device);
	429
	430	/**
	431	* cpuidle_unregister_device - unregisters a CPU's idle PM feature
	432	* @dev: the cpu
	433	*/
	434	void cpuidle_unregister_device(struct cpuidle_device *dev)
	435	{
	436	struct cpuidle_driver *drv = cpuidle_get_cpu_driver(dev);
	437
	438	if (dev->registered == 0)
	439	return;
	440
	441	cpuidle_pause_and_lock();
	442
	443	cpuidle_disable_device(dev);
	444
	445	cpuidle_remove_sysfs(dev);
	446	list_del(&dev->device_list);
	447	per_cpu(cpuidle_devices, dev->cpu) = NULL;
	448
	449	cpuidle_coupled_unregister_device(dev);
	450
	451	cpuidle_resume_and_unlock();
	452
	453	module_put(drv->owner);
	454	}
	455
	456	EXPORT_SYMBOL_GPL(cpuidle_unregister_device);
	457
	458	/**
	459	* cpuidle_unregister: unregister a driver and the devices. This function
	460	* can be used only if the driver has been previously registered through
	461	* the cpuidle_register function.
	462	*
	463	* @drv: a valid pointer to a struct cpuidle_driver
	464	*/
	465	void cpuidle_unregister(struct cpuidle_driver *drv)
	466	{
	467	int cpu;
	468	struct cpuidle_device *device;
	469
	470	for_each_cpu(cpu, drv->cpumask) {
	471	device = &per_cpu(cpuidle_dev, cpu);
	472	cpuidle_unregister_device(device);
	473	}
	474
	475	cpuidle_unregister_driver(drv);
	476	}
	477	EXPORT_SYMBOL_GPL(cpuidle_unregister);
	478
	479	/**
	480	* cpuidle_register: registers the driver and the cpu devices with the
	481	* coupled_cpus passed as parameter. This function is used for all common
	482	* initialization pattern there are in the arch specific drivers. The
	483	* devices is globally defined in this file.
	484	*
	485	* @drv : a valid pointer to a struct cpuidle_driver
	486	* @coupled_cpus: a cpumask for the coupled states
	487	*
	488	* Returns 0 on success, < 0 otherwise
	489	*/
	490	int cpuidle_register(struct cpuidle_driver *drv,
	491	const struct cpumask *const coupled_cpus)
	492	{
	493	int ret, cpu;
	494	struct cpuidle_device *device;
	495
	496	ret = cpuidle_register_driver(drv);
	497	if (ret) {
	498	pr_err("failed to register cpuidle driver\n");
	499	return ret;
	500	}
	501
	502	for_each_cpu(cpu, drv->cpumask) {
	503	device = &per_cpu(cpuidle_dev, cpu);
	504	device->cpu = cpu;
	505
	506	#ifdef CONFIG_ARCH_NEEDS_CPU_IDLE_COUPLED
	507	/*
	508	* On multiplatform for ARM, the coupled idle states could
	509	* enabled in the kernel even if the cpuidle driver does not
	510	* use it. Note, coupled_cpus is a struct copy.
	511	*/
	512	if (coupled_cpus)
	513	device->coupled_cpus = *coupled_cpus;
	514	#endif
	515	ret = cpuidle_register_device(device);
	516	if (!ret)
	517	continue;
	518
	519	pr_err("Failed to register cpuidle device for cpu%d\n", cpu);
	520
	521	cpuidle_unregister(drv);
	522	break;
	523	}
	524
	525	return ret;
	526	}
	527	EXPORT_SYMBOL_GPL(cpuidle_register);
	528
	529	#ifdef CONFIG_SMP
	530
	531	static void smp_callback(void *v)
	532	{
	533	/* we already woke the CPU up, nothing more to do */
	534	}
	535
	536	/*
	537	* This function gets called when a part of the kernel has a new latency
	538	* requirement. This means we need to get all processors out of their C-state,
	539	* and then recalculate a new suitable C-state. Just do a cross-cpu IPI; that
	540	* wakes them all right up.
	541	*/
	542	static int cpuidle_latency_notify(struct notifier_block *b,
	543	unsigned long l, void *v)
	544	{
	545	smp_call_function(smp_callback, NULL, 1);
	546	return NOTIFY_OK;
	547	}
	548
	549	static struct notifier_block cpuidle_latency_notifier = {
	550	.notifier_call = cpuidle_latency_notify,
	551	};
	552
	553	static inline void latency_notifier_init(struct notifier_block *n)
	554	{
	555	pm_qos_add_notifier(PM_QOS_CPU_DMA_LATENCY, n);
	556	}
	557
	558	#else /* CONFIG_SMP */
	559
	560	#define latency_notifier_init(x) do { } while (0)
	561
	562	#endif /* CONFIG_SMP */
	563
	564	/**
	565	* cpuidle_init - core initializer
	566	*/
	567	static int __init cpuidle_init(void)
	568	{
	569	int ret;
	570
	571	if (cpuidle_disabled())
	572	return -ENODEV;
	573
	574	ret = cpuidle_add_interface(cpu_subsys.dev_root);
	575	if (ret)
	576	return ret;
	577
	578	latency_notifier_init(&cpuidle_latency_notifier);
	579
	580	return 0;
	581	}
	582
	583	module_param(off, int, 0444);
	584	core_initcall(cpuidle_init);