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