[mirror_ubuntu-jammy-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;
}

/**
 * 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;
	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;

	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);

static void __cpuidle_unregister_device(struct cpuidle_device *dev)
{
	struct cpuidle_driver *drv = cpuidle_get_cpu_driver(dev);

	list_del(&dev->device_list);
	per_cpu(cpuidle_devices, dev->cpu) = NULL;
	module_put(drv->owner);
}

static int __cpuidle_device_init(struct cpuidle_device *dev)
{
	memset(dev->states_usage, 0, sizeof(dev->states_usage));
	dev->last_residency = 0;

	return 0;
}

/**
 * __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_coupled_register_device(dev);
	if (ret) {
		__cpuidle_unregister_device(dev);
		return ret;
	}

	dev->registered = 1;
	return 0;
}

/**
 * cpuidle_register_device - registers a CPU's idle PM feature
 * @dev: the cpu
 */
int cpuidle_register_device(struct cpuidle_device *dev)
{
	int ret = -EBUSY;

	if (!dev)
		return -EINVAL;

	mutex_lock(&cpuidle_lock);

	if (dev->registered)
		goto out_unlock;

	ret = __cpuidle_device_init(dev);
	if (ret)
		goto out_unlock;

	ret = __cpuidle_register_device(dev);
	if (ret)
		goto out_unlock;

	ret = cpuidle_add_sysfs(dev);
	if (ret)
		goto out_unregister;

	ret = cpuidle_enable_device(dev);
	if (ret)
		goto out_sysfs;

	cpuidle_install_idle_handler();

out_unlock:
	mutex_unlock(&cpuidle_lock);

	return ret;

out_sysfs:
	cpuidle_remove_sysfs(dev);
out_unregister:
	__cpuidle_unregister_device(dev);
	goto out_unlock;
}

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

	cpuidle_pause_and_lock();

	cpuidle_disable_device(dev);

	cpuidle_remove_sysfs(dev);

	__cpuidle_unregister_device(dev);

	cpuidle_coupled_unregister_device(dev);

	cpuidle_resume_and_unlock();
}

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 be
		 * 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	/**
	46	* cpuidle_play_dead - cpu off-lining
	47	*
	48	* Returns in case of an error or no driver
	49	*/
	50	int cpuidle_play_dead(void)
	51	{
	52	struct cpuidle_device *dev = __this_cpu_read(cpuidle_devices);
	53	struct cpuidle_driver *drv = cpuidle_get_cpu_driver(dev);
	54	int i;
	55
	56	if (!drv)
	57	return -ENODEV;
	58
	59	/* Find lowest-power state that supports long-term idle */
	60	for (i = drv->state_count - 1; i >= CPUIDLE_DRIVER_STATE_START; i--)
	61	if (drv->states[i].enter_dead)
	62	return drv->states[i].enter_dead(dev, i);
	63
	64	return -ENODEV;
	65	}
	66
	67	/**
	68	* cpuidle_enter_state - enter the state and update stats
	69	* @dev: cpuidle device for this cpu
	70	* @drv: cpuidle driver for this cpu
	71	* @next_state: index into drv->states of the state to enter
	72	*/
	73	int cpuidle_enter_state(struct cpuidle_device dev, struct cpuidle_driver drv,
	74	int index)
	75	{
	76	int entered_state;
	77
	78	struct cpuidle_state *target_state = &drv->states[index];
	79	ktime_t time_start, time_end;
	80	s64 diff;
	81
	82	time_start = ktime_get();
	83
	84	entered_state = target_state->enter(dev, drv, index);
	85
	86	time_end = ktime_get();
	87
	88	local_irq_enable();
	89
	90	diff = ktime_to_us(ktime_sub(time_end, time_start));
	91	if (diff > INT_MAX)
	92	diff = INT_MAX;
	93
	94	dev->last_residency = (int) diff;
	95
	96	if (entered_state >= 0) {
	97	/* Update cpuidle counters */
	98	/* This can be moved to within driver enter routine
	99	* but that results in multiple copies of same code.
	100	*/
	101	dev->states_usage[entered_state].time += dev->last_residency;
	102	dev->states_usage[entered_state].usage++;
	103	} else {
	104	dev->last_residency = 0;
	105	}
	106
	107	return entered_state;
	108	}
	109
	110	/**
	111	* cpuidle_idle_call - the main idle loop
	112	*
	113	* NOTE: no locks or semaphores should be used here
	114	* return non-zero on failure
	115	*/
	116	int cpuidle_idle_call(void)
	117	{
	118	struct cpuidle_device *dev = __this_cpu_read(cpuidle_devices);
	119	struct cpuidle_driver *drv;
	120	int next_state, entered_state;
	121
	122	if (off)
	123	return -ENODEV;
	124
	125	if (!initialized)
	126	return -ENODEV;
	127
	128	/* check if the device is ready */
	129	if (!dev \|\| !dev->enabled)
	130	return -EBUSY;
	131
	132	drv = cpuidle_get_cpu_driver(dev);
	133
	134	/* ask the governor for the next state */
	135	next_state = cpuidle_curr_governor->select(drv, dev);
	136	if (need_resched()) {
	137	dev->last_residency = 0;
	138	/* give the governor an opportunity to reflect on the outcome */
	139	if (cpuidle_curr_governor->reflect)
	140	cpuidle_curr_governor->reflect(dev, next_state);
	141	local_irq_enable();
	142	return 0;
	143	}
	144
	145	trace_cpu_idle_rcuidle(next_state, dev->cpu);
	146
	147	if (drv->states[next_state].flags & CPUIDLE_FLAG_TIMER_STOP)
	148	clockevents_notify(CLOCK_EVT_NOTIFY_BROADCAST_ENTER,
	149	&dev->cpu);
	150
	151	if (cpuidle_state_is_coupled(dev, drv, next_state))
	152	entered_state = cpuidle_enter_state_coupled(dev, drv,
	153	next_state);
	154	else
	155	entered_state = cpuidle_enter_state(dev, drv, next_state);
	156
	157	if (drv->states[next_state].flags & CPUIDLE_FLAG_TIMER_STOP)
	158	clockevents_notify(CLOCK_EVT_NOTIFY_BROADCAST_EXIT,
	159	&dev->cpu);
	160
	161	trace_cpu_idle_rcuidle(PWR_EVENT_EXIT, dev->cpu);
	162
	163	/* give the governor an opportunity to reflect on the outcome */
	164	if (cpuidle_curr_governor->reflect)
	165	cpuidle_curr_governor->reflect(dev, entered_state);
	166
	167	return 0;
	168	}
	169
	170	/**
	171	* cpuidle_install_idle_handler - installs the cpuidle idle loop handler
	172	*/
	173	void cpuidle_install_idle_handler(void)
	174	{
	175	if (enabled_devices) {
	176	/* Make sure all changes finished before we switch to new idle */
	177	smp_wmb();
	178	initialized = 1;
	179	}
	180	}
	181
	182	/**
	183	* cpuidle_uninstall_idle_handler - uninstalls the cpuidle idle loop handler
	184	*/
	185	void cpuidle_uninstall_idle_handler(void)
	186	{
	187	if (enabled_devices) {
	188	initialized = 0;
	189	kick_all_cpus_sync();
	190	}
	191	}
	192
	193	/**
	194	* cpuidle_pause_and_lock - temporarily disables CPUIDLE
	195	*/
	196	void cpuidle_pause_and_lock(void)
	197	{
	198	mutex_lock(&cpuidle_lock);
	199	cpuidle_uninstall_idle_handler();
	200	}
	201
	202	EXPORT_SYMBOL_GPL(cpuidle_pause_and_lock);
	203
	204	/**
	205	* cpuidle_resume_and_unlock - resumes CPUIDLE operation
	206	*/
	207	void cpuidle_resume_and_unlock(void)
	208	{
	209	cpuidle_install_idle_handler();
	210	mutex_unlock(&cpuidle_lock);
	211	}
	212
	213	EXPORT_SYMBOL_GPL(cpuidle_resume_and_unlock);
	214
	215	/* Currently used in suspend/resume path to suspend cpuidle */
	216	void cpuidle_pause(void)
	217	{
	218	mutex_lock(&cpuidle_lock);
	219	cpuidle_uninstall_idle_handler();
	220	mutex_unlock(&cpuidle_lock);
	221	}
	222
	223	/* Currently used in suspend/resume path to resume cpuidle */
	224	void cpuidle_resume(void)
	225	{
	226	mutex_lock(&cpuidle_lock);
	227	cpuidle_install_idle_handler();
	228	mutex_unlock(&cpuidle_lock);
	229	}
	230
	231	#ifdef CONFIG_ARCH_HAS_CPU_RELAX
	232	static int poll_idle(struct cpuidle_device *dev,
	233	struct cpuidle_driver *drv, int index)
	234	{
	235	ktime_t t1, t2;
	236	s64 diff;
	237
	238	t1 = ktime_get();
	239	local_irq_enable();
	240	while (!need_resched())
	241	cpu_relax();
	242
	243	t2 = ktime_get();
	244	diff = ktime_to_us(ktime_sub(t2, t1));
	245	if (diff > INT_MAX)
	246	diff = INT_MAX;
	247
	248	dev->last_residency = (int) diff;
	249
	250	return index;
	251	}
	252
	253	static void poll_idle_init(struct cpuidle_driver *drv)
	254	{
	255	struct cpuidle_state *state = &drv->states[0];
	256
	257	snprintf(state->name, CPUIDLE_NAME_LEN, "POLL");
	258	snprintf(state->desc, CPUIDLE_DESC_LEN, "CPUIDLE CORE POLL IDLE");
	259	state->exit_latency = 0;
	260	state->target_residency = 0;
	261	state->power_usage = -1;
	262	state->flags = 0;
	263	state->enter = poll_idle;
	264	state->disabled = false;
	265	}
	266	#else
	267	static void poll_idle_init(struct cpuidle_driver *drv) {}
	268	#endif /* CONFIG_ARCH_HAS_CPU_RELAX */
	269
	270	/**
	271	* cpuidle_enable_device - enables idle PM for a CPU
	272	* @dev: the CPU
	273	*
	274	* This function must be called between cpuidle_pause_and_lock and
	275	* cpuidle_resume_and_unlock when used externally.
	276	*/
	277	int cpuidle_enable_device(struct cpuidle_device *dev)
	278	{
	279	int ret;
	280	struct cpuidle_driver *drv;
	281
	282	if (!dev)
	283	return -EINVAL;
	284
	285	if (dev->enabled)
	286	return 0;
	287
	288	drv = cpuidle_get_cpu_driver(dev);
	289
	290	if (!drv \|\| !cpuidle_curr_governor)
	291	return -EIO;
	292
	293	if (!dev->registered)
	294	return -EINVAL;
	295
	296	if (!dev->state_count)
	297	dev->state_count = drv->state_count;
	298
	299	poll_idle_init(drv);
	300
	301	ret = cpuidle_add_device_sysfs(dev);
	302	if (ret)
	303	return ret;
	304
	305	if (cpuidle_curr_governor->enable &&
	306	(ret = cpuidle_curr_governor->enable(drv, dev)))
	307	goto fail_sysfs;
	308
	309	smp_wmb();
	310
	311	dev->enabled = 1;
	312
	313	enabled_devices++;
	314	return 0;
	315
	316	fail_sysfs:
	317	cpuidle_remove_device_sysfs(dev);
	318
	319	return ret;
	320	}
	321
	322	EXPORT_SYMBOL_GPL(cpuidle_enable_device);
	323
	324	/**
	325	* cpuidle_disable_device - disables idle PM for a CPU
	326	* @dev: the CPU
	327	*
	328	* This function must be called between cpuidle_pause_and_lock and
	329	* cpuidle_resume_and_unlock when used externally.
	330	*/
	331	void cpuidle_disable_device(struct cpuidle_device *dev)
	332	{
	333	struct cpuidle_driver *drv = cpuidle_get_cpu_driver(dev);
	334
	335	if (!dev \|\| !dev->enabled)
	336	return;
	337
	338	if (!drv \|\| !cpuidle_curr_governor)
	339	return;
	340
	341	dev->enabled = 0;
	342
	343	if (cpuidle_curr_governor->disable)
	344	cpuidle_curr_governor->disable(drv, dev);
	345
	346	cpuidle_remove_device_sysfs(dev);
	347	enabled_devices--;
	348	}
	349
	350	EXPORT_SYMBOL_GPL(cpuidle_disable_device);
	351
	352	static void __cpuidle_unregister_device(struct cpuidle_device *dev)
	353	{
	354	struct cpuidle_driver *drv = cpuidle_get_cpu_driver(dev);
	355
	356	list_del(&dev->device_list);
	357	per_cpu(cpuidle_devices, dev->cpu) = NULL;
	358	module_put(drv->owner);
	359	}
	360
	361	static int __cpuidle_device_init(struct cpuidle_device *dev)
	362	{
	363	memset(dev->states_usage, 0, sizeof(dev->states_usage));
	364	dev->last_residency = 0;
	365
	366	return 0;
	367	}
	368
	369	/**
	370	* __cpuidle_register_device - internal register function called before register
	371	* and enable routines
	372	* @dev: the cpu
	373	*
	374	* cpuidle_lock mutex must be held before this is called
	375	*/
	376	static int __cpuidle_register_device(struct cpuidle_device *dev)
	377	{
	378	int ret;
	379	struct cpuidle_driver *drv = cpuidle_get_cpu_driver(dev);
	380
	381	if (!try_module_get(drv->owner))
	382	return -EINVAL;
	383
	384	per_cpu(cpuidle_devices, dev->cpu) = dev;
	385	list_add(&dev->device_list, &cpuidle_detected_devices);
	386
	387	ret = cpuidle_coupled_register_device(dev);
	388	if (ret) {
	389	__cpuidle_unregister_device(dev);
	390	return ret;
	391	}
	392
	393	dev->registered = 1;
	394	return 0;
	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 = -EBUSY;
	404
	405	if (!dev)
	406	return -EINVAL;
	407
	408	mutex_lock(&cpuidle_lock);
	409
	410	if (dev->registered)
	411	goto out_unlock;
	412
	413	ret = __cpuidle_device_init(dev);
	414	if (ret)
	415	goto out_unlock;
	416
	417	ret = __cpuidle_register_device(dev);
	418	if (ret)
	419	goto out_unlock;
	420
	421	ret = cpuidle_add_sysfs(dev);
	422	if (ret)
	423	goto out_unregister;
	424
	425	ret = cpuidle_enable_device(dev);
	426	if (ret)
	427	goto out_sysfs;
	428
	429	cpuidle_install_idle_handler();
	430
	431	out_unlock:
	432	mutex_unlock(&cpuidle_lock);
	433
	434	return ret;
	435
	436	out_sysfs:
	437	cpuidle_remove_sysfs(dev);
	438	out_unregister:
	439	__cpuidle_unregister_device(dev);
	440	goto out_unlock;
	441	}
	442
	443	EXPORT_SYMBOL_GPL(cpuidle_register_device);
	444
	445	/**
	446	* cpuidle_unregister_device - unregisters a CPU's idle PM feature
	447	* @dev: the cpu
	448	*/
	449	void cpuidle_unregister_device(struct cpuidle_device *dev)
	450	{
	451	if (dev->registered == 0)
	452	return;
	453
	454	cpuidle_pause_and_lock();
	455
	456	cpuidle_disable_device(dev);
	457
	458	cpuidle_remove_sysfs(dev);
	459
	460	__cpuidle_unregister_device(dev);
	461
	462	cpuidle_coupled_unregister_device(dev);
	463
	464	cpuidle_resume_and_unlock();
	465	}
	466
	467	EXPORT_SYMBOL_GPL(cpuidle_unregister_device);
	468
	469	/**
	470	* cpuidle_unregister: unregister a driver and the devices. This function
	471	* can be used only if the driver has been previously registered through
	472	* the cpuidle_register function.
	473	*
	474	* @drv: a valid pointer to a struct cpuidle_driver
	475	*/
	476	void cpuidle_unregister(struct cpuidle_driver *drv)
	477	{
	478	int cpu;
	479	struct cpuidle_device *device;
	480
	481	for_each_cpu(cpu, drv->cpumask) {
	482	device = &per_cpu(cpuidle_dev, cpu);
	483	cpuidle_unregister_device(device);
	484	}
	485
	486	cpuidle_unregister_driver(drv);
	487	}
	488	EXPORT_SYMBOL_GPL(cpuidle_unregister);
	489
	490	/**
	491	* cpuidle_register: registers the driver and the cpu devices with the
	492	* coupled_cpus passed as parameter. This function is used for all common
	493	* initialization pattern there are in the arch specific drivers. The
	494	* devices is globally defined in this file.
	495	*
	496	* @drv : a valid pointer to a struct cpuidle_driver
	497	* @coupled_cpus: a cpumask for the coupled states
	498	*
	499	* Returns 0 on success, < 0 otherwise
	500	*/
	501	int cpuidle_register(struct cpuidle_driver *drv,
	502	const struct cpumask *const coupled_cpus)
	503	{
	504	int ret, cpu;
	505	struct cpuidle_device *device;
	506
	507	ret = cpuidle_register_driver(drv);
	508	if (ret) {
	509	pr_err("failed to register cpuidle driver\n");
	510	return ret;
	511	}
	512
	513	for_each_cpu(cpu, drv->cpumask) {
	514	device = &per_cpu(cpuidle_dev, cpu);
	515	device->cpu = cpu;
	516
	517	#ifdef CONFIG_ARCH_NEEDS_CPU_IDLE_COUPLED
	518	/*
	519	* On multiplatform for ARM, the coupled idle states could be
	520	* enabled in the kernel even if the cpuidle driver does not
	521	* use it. Note, coupled_cpus is a struct copy.
	522	*/
	523	if (coupled_cpus)
	524	device->coupled_cpus = *coupled_cpus;
	525	#endif
	526	ret = cpuidle_register_device(device);
	527	if (!ret)
	528	continue;
	529
	530	pr_err("Failed to register cpuidle device for cpu%d\n", cpu);
	531
	532	cpuidle_unregister(drv);
	533	break;
	534	}
	535
	536	return ret;
	537	}
	538	EXPORT_SYMBOL_GPL(cpuidle_register);
	539
	540	#ifdef CONFIG_SMP
	541
	542	static void smp_callback(void *v)
	543	{
	544	/* we already woke the CPU up, nothing more to do */
	545	}
	546
	547	/*
	548	* This function gets called when a part of the kernel has a new latency
	549	* requirement. This means we need to get all processors out of their C-state,
	550	* and then recalculate a new suitable C-state. Just do a cross-cpu IPI; that
	551	* wakes them all right up.
	552	*/
	553	static int cpuidle_latency_notify(struct notifier_block *b,
	554	unsigned long l, void *v)
	555	{
	556	smp_call_function(smp_callback, NULL, 1);
	557	return NOTIFY_OK;
	558	}
	559
	560	static struct notifier_block cpuidle_latency_notifier = {
	561	.notifier_call = cpuidle_latency_notify,
	562	};
	563
	564	static inline void latency_notifier_init(struct notifier_block *n)
	565	{
	566	pm_qos_add_notifier(PM_QOS_CPU_DMA_LATENCY, n);
	567	}
	568
	569	#else /* CONFIG_SMP */
	570
	571	#define latency_notifier_init(x) do { } while (0)
	572
	573	#endif /* CONFIG_SMP */
	574
	575	/**
	576	* cpuidle_init - core initializer
	577	*/
	578	static int __init cpuidle_init(void)
	579	{
	580	int ret;
	581
	582	if (cpuidle_disabled())
	583	return -ENODEV;
	584
	585	ret = cpuidle_add_interface(cpu_subsys.dev_root);
	586	if (ret)
	587	return ret;
	588
	589	latency_notifier_init(&cpuidle_latency_notifier);
	590
	591	return 0;
	592	}
	593
	594	module_param(off, int, 0444);
	595	core_initcall(cpuidle_init);