[linux-2.6-block.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 <linux/suspend.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_find_deepest_state - Find deepest state meeting specific conditions.
 * @drv: cpuidle driver for the given CPU.
 * @dev: cpuidle device for the given CPU.
 */
static int cpuidle_find_deepest_state(struct cpuidle_driver *drv,
				      struct cpuidle_device *dev)
{
	unsigned int latency_req = 0;
	int i, ret = CPUIDLE_DRIVER_STATE_START - 1;

	for (i = CPUIDLE_DRIVER_STATE_START; i < drv->state_count; i++) {
		struct cpuidle_state *s = &drv->states[i];
		struct cpuidle_state_usage *su = &dev->states_usage[i];

		if (s->disabled || su->disable || s->exit_latency <= latency_req)
			continue;

		latency_req = s->exit_latency;
		ret = i;
	}
	return ret;
}

/**
 * cpuidle_enter_freeze - Enter an idle state suitable for suspend-to-idle.
 *
 * Find the deepest state available and enter it.
 */
void cpuidle_enter_freeze(void)
{
	struct cpuidle_device *dev = __this_cpu_read(cpuidle_devices);
	struct cpuidle_driver *drv = cpuidle_get_cpu_driver(dev);
	int index;

	index = cpuidle_find_deepest_state(drv, dev);
	if (index >= 0)
		cpuidle_enter(drv, dev, index);
	else
		arch_cpu_idle();

	/* Interrupts are enabled again here. */
	local_irq_disable();
}

/**
 * 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;

	trace_cpu_idle_rcuidle(index, dev->cpu);
	time_start = ktime_get();

	entered_state = target_state->enter(dev, drv, index);

	time_end = ktime_get();
	trace_cpu_idle_rcuidle(PWR_EVENT_EXIT, dev->cpu);

	if (!cpuidle_state_is_coupled(dev, drv, entered_state))
		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_select - ask the cpuidle framework to choose an idle state
 *
 * @drv: the cpuidle driver
 * @dev: the cpuidle device
 *
 * Returns the index of the idle state.
 */
int cpuidle_select(struct cpuidle_driver *drv, struct cpuidle_device *dev)
{
	if (off || !initialized)
		return -ENODEV;

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

	return cpuidle_curr_governor->select(drv, dev);
}

/**
 * cpuidle_enter - enter into the specified idle state
 *
 * @drv:   the cpuidle driver tied with the cpu
 * @dev:   the cpuidle device
 * @index: the index in the idle state table
 *
 * Returns the index in the idle state, < 0 in case of error.
 * The error code depends on the backend driver
 */
int cpuidle_enter(struct cpuidle_driver *drv, struct cpuidle_device *dev,
		  int index)
{
	if (cpuidle_state_is_coupled(dev, drv, index))
		return cpuidle_enter_state_coupled(dev, drv, index);
	return cpuidle_enter_state(dev, drv, index);
}

/**
 * cpuidle_reflect - tell the underlying governor what was the state
 * we were in
 *
 * @dev  : the cpuidle device
 * @index: the index in the idle state table
 *
 */
void cpuidle_reflect(struct cpuidle_device *dev, int index)
{
	if (cpuidle_curr_governor->reflect)
		cpuidle_curr_governor->reflect(dev, index);
}

/**
 * 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;
		wake_up_all_idle_cpus();
	}

	/*
	 * Make sure external observers (such as the scheduler)
	 * are done looking at pointed idle states.
	 */
	synchronize_rcu();
}

/**
 * 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_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;

	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 void __cpuidle_device_init(struct cpuidle_device *dev)
{
	memset(dev->states_usage, 0, sizeof(dev->states_usage));
	dev->last_residency = 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);
	else
		dev->registered = 1;

	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 = -EBUSY;

	if (!dev)
		return -EINVAL;

	mutex_lock(&cpuidle_lock);

	if (dev->registered)
		goto out_unlock;

	__cpuidle_device_init(dev);

	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 || 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

/*
 * 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)
{
	wake_up_all_idle_cpus();
	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>
38106313	22	#include <linux/suspend.h>
288f023e	23	#include <trace/events/power.h>
4f86d3a8 LB	24
	25	#include "cpuidle.h"
	26
	27	DEFINE_PER_CPU(struct cpuidle_device *, cpuidle_devices);
4c637b21	28	DEFINE_PER_CPU(struct cpuidle_device, cpuidle_dev);
4f86d3a8 LB	29
	30	DEFINE_MUTEX(cpuidle_lock);
	31	LIST_HEAD(cpuidle_detected_devices);
4f86d3a8 LB	32
4f86d3a8 LB	33	static int enabled_devices;
62027aea	34	static int off __read_mostly;
a0bfa137	35	static int initialized __read_mostly;
62027aea LB	36
	37	int cpuidle_disabled(void)
	38	{
	39	return off;
	40	}
d91ee586 LB	41	void disable_cpuidle(void)
	42	{
	43	off = 1;
	44	}
4f86d3a8	45
1a022e3f BO	46	/**
	47	* cpuidle_play_dead - cpu off-lining
	48	*
ee01e663	49	* Returns in case of an error or no driver
1a022e3f BO	50	*/
	51	int cpuidle_play_dead(void)
	52	{
	53	struct cpuidle_device *dev = __this_cpu_read(cpuidle_devices);
bf4d1b5d	54	struct cpuidle_driver *drv = cpuidle_get_cpu_driver(dev);
8aef33a7	55	int i;
1a022e3f	56
ee01e663 TK	57	if (!drv)
	58	return -ENODEV;
	59
1a022e3f	60	/* Find lowest-power state that supports long-term idle */
8aef33a7 DL	61	for (i = drv->state_count - 1; i >= CPUIDLE_DRIVER_STATE_START; i--)
	62	if (drv->states[i].enter_dead)
	63	return drv->states[i].enter_dead(dev, i);
1a022e3f BO	64
	65	return -ENODEV;
	66	}
	67
a6220fc1	68	/**
38106313 RW	69	* cpuidle_find_deepest_state - Find deepest state meeting specific conditions.
	70	* @drv: cpuidle driver for the given CPU.
	71	* @dev: cpuidle device for the given CPU.
a6220fc1 RW	72	*/
	73	static int cpuidle_find_deepest_state(struct cpuidle_driver *drv,
	74	struct cpuidle_device *dev)
	75	{
	76	unsigned int latency_req = 0;
	77	int i, ret = CPUIDLE_DRIVER_STATE_START - 1;
	78
	79	for (i = CPUIDLE_DRIVER_STATE_START; i < drv->state_count; i++) {
	80	struct cpuidle_state *s = &drv->states[i];
	81	struct cpuidle_state_usage *su = &dev->states_usage[i];
	82
	83	if (s->disabled \|\| su->disable \|\| s->exit_latency <= latency_req)
	84	continue;
	85
	86	latency_req = s->exit_latency;
	87	ret = i;
	88	}
	89	return ret;
	90	}
	91
38106313 RW	92	/**
	93	* cpuidle_enter_freeze - Enter an idle state suitable for suspend-to-idle.
	94	*
	95	* Find the deepest state available and enter it.
	96	*/
	97	void cpuidle_enter_freeze(void)
	98	{
	99	struct cpuidle_device *dev = __this_cpu_read(cpuidle_devices);
	100	struct cpuidle_driver *drv = cpuidle_get_cpu_driver(dev);
	101	int index;
	102
	103	index = cpuidle_find_deepest_state(drv, dev);
	104	if (index >= 0)
	105	cpuidle_enter(drv, dev, index);
	106	else
	107	arch_cpu_idle();
	108
	109	/* Interrupts are enabled again here. */
	110	local_irq_disable();
	111	}
	112
56cfbf74 CC	113	/**
	114	* cpuidle_enter_state - enter the state and update stats
	115	* @dev: cpuidle device for this cpu
	116	* @drv: cpuidle driver for this cpu
	117	* @next_state: index into drv->states of the state to enter
	118	*/
	119	int cpuidle_enter_state(struct cpuidle_device dev, struct cpuidle_driver drv,
554c06ba	120	int index)
56cfbf74 CC	121	{
	122	int entered_state;
	123
554c06ba DL	124	struct cpuidle_state *target_state = &drv->states[index];
	125	ktime_t time_start, time_end;
	126	s64 diff;
	127
30fe6884	128	trace_cpu_idle_rcuidle(index, dev->cpu);
554c06ba DL	129	time_start = ktime_get();
	130
	131	entered_state = target_state->enter(dev, drv, index);
	132
	133	time_end = ktime_get();
30fe6884	134	trace_cpu_idle_rcuidle(PWR_EVENT_EXIT, dev->cpu);
554c06ba	135
0b89e9aa PB	136	if (!cpuidle_state_is_coupled(dev, drv, entered_state))
0b89e9aa PB	137	local_irq_enable();
554c06ba DL	138
	139	diff = ktime_to_us(ktime_sub(time_end, time_start));
	140	if (diff > INT_MAX)
	141	diff = INT_MAX;
	142
	143	dev->last_residency = (int) diff;
56cfbf74 CC	144
	145	if (entered_state >= 0) {
	146	/* Update cpuidle counters */
	147	/* This can be moved to within driver enter routine
	148	* but that results in multiple copies of same code.
	149	*/
a474a515	150	dev->states_usage[entered_state].time += dev->last_residency;
56cfbf74 CC	151	dev->states_usage[entered_state].usage++;
	152	} else {
	153	dev->last_residency = 0;
	154	}
	155
	156	return entered_state;
	157	}
	158
4f86d3a8	159	/**
907e30f1 DL	160	* cpuidle_select - ask the cpuidle framework to choose an idle state
	161	*
	162	* @drv: the cpuidle driver
	163	* @dev: the cpuidle device
4f86d3a8	164	*
907e30f1	165	* Returns the index of the idle state.
4f86d3a8	166	*/
907e30f1	167	int cpuidle_select(struct cpuidle_driver drv, struct cpuidle_device dev)
4f86d3a8	168	{
52c324f8 RW	169	if (off \|\| !initialized)
	170	return -ENODEV;
	171
	172	if (!drv \|\| !dev \|\| !dev->enabled)
	173	return -EBUSY;
	174
907e30f1 DL	175	return cpuidle_curr_governor->select(drv, dev);
907e30f1 DL	176	}
ba8f20c2	177
907e30f1 DL	178	/**
	179	* cpuidle_enter - enter into the specified idle state
	180	*
	181	* @drv: the cpuidle driver tied with the cpu
	182	* @dev: the cpuidle device
	183	* @index: the index in the idle state table
	184	*
	185	* Returns the index in the idle state, < 0 in case of error.
	186	* The error code depends on the backend driver
	187	*/
	188	int cpuidle_enter(struct cpuidle_driver drv, struct cpuidle_device dev,
	189	int index)
	190	{
	191	if (cpuidle_state_is_coupled(dev, drv, index))
	192	return cpuidle_enter_state_coupled(dev, drv, index);
	193	return cpuidle_enter_state(dev, drv, index);
	194	}
b60e6a0e	195
907e30f1 DL	196	/**
	197	* cpuidle_reflect - tell the underlying governor what was the state
	198	* we were in
	199	*
	200	* @dev : the cpuidle device
	201	* @index: the index in the idle state table
	202	*
	203	*/
	204	void cpuidle_reflect(struct cpuidle_device *dev, int index)
	205	{
38106313	206	if (cpuidle_curr_governor->reflect)
907e30f1	207	cpuidle_curr_governor->reflect(dev, index);
4f86d3a8 LB	208	}
	209
	210	/**
	211	* cpuidle_install_idle_handler - installs the cpuidle idle loop handler
	212	*/
	213	void cpuidle_install_idle_handler(void)
	214	{
a0bfa137	215	if (enabled_devices) {
4f86d3a8 LB	216	/* Make sure all changes finished before we switch to new idle */
4f86d3a8 LB	217	smp_wmb();
a0bfa137	218	initialized = 1;
4f86d3a8 LB	219	}
	220	}
	221
	222	/**
	223	* cpuidle_uninstall_idle_handler - uninstalls the cpuidle idle loop handler
	224	*/
	225	void cpuidle_uninstall_idle_handler(void)
	226	{
a0bfa137 LB	227	if (enabled_devices) {
a0bfa137 LB	228	initialized = 0;
2ed903c5	229	wake_up_all_idle_cpus();
4f86d3a8	230	}
442bf3aa DL	231
	232	/*
	233	* Make sure external observers (such as the scheduler)
	234	* are done looking at pointed idle states.
	235	*/
	236	synchronize_rcu();
4f86d3a8 LB	237	}
	238
	239	/**
	240	* cpuidle_pause_and_lock - temporarily disables CPUIDLE
	241	*/
	242	void cpuidle_pause_and_lock(void)
	243	{
	244	mutex_lock(&cpuidle_lock);
	245	cpuidle_uninstall_idle_handler();
	246	}
	247
	248	EXPORT_SYMBOL_GPL(cpuidle_pause_and_lock);
	249
	250	/**
	251	* cpuidle_resume_and_unlock - resumes CPUIDLE operation
	252	*/
	253	void cpuidle_resume_and_unlock(void)
	254	{
	255	cpuidle_install_idle_handler();
	256	mutex_unlock(&cpuidle_lock);
	257	}
	258
	259	EXPORT_SYMBOL_GPL(cpuidle_resume_and_unlock);
	260
8651f97b PM	261	/* Currently used in suspend/resume path to suspend cpuidle */
	262	void cpuidle_pause(void)
	263	{
	264	mutex_lock(&cpuidle_lock);
	265	cpuidle_uninstall_idle_handler();
	266	mutex_unlock(&cpuidle_lock);
	267	}
	268
	269	/* Currently used in suspend/resume path to resume cpuidle */
	270	void cpuidle_resume(void)
	271	{
	272	mutex_lock(&cpuidle_lock);
	273	cpuidle_install_idle_handler();
	274	mutex_unlock(&cpuidle_lock);
	275	}
	276
4f86d3a8 LB	277	/**
	278	* cpuidle_enable_device - enables idle PM for a CPU
	279	* @dev: the CPU
	280	*
	281	* This function must be called between cpuidle_pause_and_lock and
	282	* cpuidle_resume_and_unlock when used externally.
	283	*/
	284	int cpuidle_enable_device(struct cpuidle_device *dev)
	285	{
5df0aa73	286	int ret;
bf4d1b5d	287	struct cpuidle_driver *drv;
4f86d3a8	288
1b0a0e9a SB	289	if (!dev)
	290	return -EINVAL;
	291
4f86d3a8 LB	292	if (dev->enabled)
4f86d3a8 LB	293	return 0;
bf4d1b5d DL	294
	295	drv = cpuidle_get_cpu_driver(dev);
	296
e1689795	297	if (!drv \|\| !cpuidle_curr_governor)
4f86d3a8	298	return -EIO;
bf4d1b5d	299
10b9d3f8 DL	300	if (!dev->registered)
	301	return -EINVAL;
	302
4f86d3a8	303	if (!dev->state_count)
fc850f39	304	dev->state_count = drv->state_count;
4f86d3a8	305
bf4d1b5d DL	306	ret = cpuidle_add_device_sysfs(dev);
bf4d1b5d DL	307	if (ret)
4f86d3a8 LB	308	return ret;
	309
	310	if (cpuidle_curr_governor->enable &&
e1689795	311	(ret = cpuidle_curr_governor->enable(drv, dev)))
4f86d3a8 LB	312	goto fail_sysfs;
4f86d3a8 LB	313
4f86d3a8 LB	314	smp_wmb();
	315
	316	dev->enabled = 1;
	317
	318	enabled_devices++;
	319	return 0;
	320
	321	fail_sysfs:
bf4d1b5d	322	cpuidle_remove_device_sysfs(dev);
4f86d3a8 LB	323
	324	return ret;
	325	}
	326
	327	EXPORT_SYMBOL_GPL(cpuidle_enable_device);
	328
	329	/**
	330	* cpuidle_disable_device - disables idle PM for a CPU
	331	* @dev: the CPU
	332	*
	333	* This function must be called between cpuidle_pause_and_lock and
	334	* cpuidle_resume_and_unlock when used externally.
	335	*/
	336	void cpuidle_disable_device(struct cpuidle_device *dev)
	337	{
bf4d1b5d DL	338	struct cpuidle_driver *drv = cpuidle_get_cpu_driver(dev);
bf4d1b5d DL	339
cf31cd1a	340	if (!dev \|\| !dev->enabled)
4f86d3a8	341	return;
bf4d1b5d DL	342
bf4d1b5d DL	343	if (!drv \|\| !cpuidle_curr_governor)
4f86d3a8 LB	344	return;
	345
	346	dev->enabled = 0;
	347
	348	if (cpuidle_curr_governor->disable)
bf4d1b5d	349	cpuidle_curr_governor->disable(drv, dev);
4f86d3a8	350
bf4d1b5d	351	cpuidle_remove_device_sysfs(dev);
4f86d3a8 LB	352	enabled_devices--;
	353	}
	354
	355	EXPORT_SYMBOL_GPL(cpuidle_disable_device);
	356
f6bb51a5 DL	357	static void __cpuidle_unregister_device(struct cpuidle_device *dev)
	358	{
	359	struct cpuidle_driver *drv = cpuidle_get_cpu_driver(dev);
	360
	361	list_del(&dev->device_list);
	362	per_cpu(cpuidle_devices, dev->cpu) = NULL;
	363	module_put(drv->owner);
	364	}
	365
267d4bf8	366	static void __cpuidle_device_init(struct cpuidle_device *dev)
5df0aa73 DL	367	{
	368	memset(dev->states_usage, 0, sizeof(dev->states_usage));
	369	dev->last_residency = 0;
5df0aa73 DL	370	}
5df0aa73 DL	371
4f86d3a8	372	/**
dcb84f33 VP	373	* __cpuidle_register_device - internal register function called before register
dcb84f33 VP	374	* and enable routines
4f86d3a8	375	* @dev: the cpu
dcb84f33 VP	376	*
dcb84f33 VP	377	* cpuidle_lock mutex must be held before this is called
4f86d3a8	378	*/
dcb84f33	379	static int __cpuidle_register_device(struct cpuidle_device *dev)
4f86d3a8 LB	380	{
4f86d3a8 LB	381	int ret;
bf4d1b5d	382	struct cpuidle_driver *drv = cpuidle_get_cpu_driver(dev);
4f86d3a8	383
bf4d1b5d	384	if (!try_module_get(drv->owner))
4f86d3a8 LB	385	return -EINVAL;
4f86d3a8 LB	386
4f86d3a8 LB	387	per_cpu(cpuidle_devices, dev->cpu) = dev;
4f86d3a8 LB	388	list_add(&dev->device_list, &cpuidle_detected_devices);
4f86d3a8	389
4126c019	390	ret = cpuidle_coupled_register_device(dev);
47182668	391	if (ret)
f6bb51a5	392	__cpuidle_unregister_device(dev);
47182668 VK	393	else
47182668 VK	394	dev->registered = 1;
4f86d3a8	395
47182668	396	return ret;
dcb84f33 VP	397	}
	398
	399	/**
	400	* cpuidle_register_device - registers a CPU's idle PM feature
	401	* @dev: the cpu
	402	*/
	403	int cpuidle_register_device(struct cpuidle_device *dev)
	404	{
c878a52d	405	int ret = -EBUSY;
dcb84f33	406
1b0a0e9a SB	407	if (!dev)
	408	return -EINVAL;
	409
dcb84f33 VP	410	mutex_lock(&cpuidle_lock);
dcb84f33 VP	411
c878a52d DL	412	if (dev->registered)
	413	goto out_unlock;
	414
267d4bf8	415	__cpuidle_device_init(dev);
5df0aa73	416
f6bb51a5 DL	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;
dcb84f33	424
10b9d3f8	425	ret = cpuidle_enable_device(dev);
f6bb51a5 DL	426	if (ret)
f6bb51a5 DL	427	goto out_sysfs;
10b9d3f8	428
4f86d3a8 LB	429	cpuidle_install_idle_handler();
4f86d3a8 LB	430
f6bb51a5	431	out_unlock:
4f86d3a8 LB	432	mutex_unlock(&cpuidle_lock);
4f86d3a8 LB	433
f6bb51a5 DL	434	return ret;
	435
	436	out_sysfs:
	437	cpuidle_remove_sysfs(dev);
	438	out_unregister:
	439	__cpuidle_unregister_device(dev);
	440	goto out_unlock;
4f86d3a8 LB	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	{
813e8e3d	451	if (!dev \|\| dev->registered == 0)
dcb84f33 VP	452	return;
dcb84f33 VP	453
4f86d3a8 LB	454	cpuidle_pause_and_lock();
	455
	456	cpuidle_disable_device(dev);
	457
1aef40e2	458	cpuidle_remove_sysfs(dev);
f6bb51a5 DL	459
f6bb51a5 DL	460	__cpuidle_unregister_device(dev);
4f86d3a8	461
4126c019 CC	462	cpuidle_coupled_unregister_device(dev);
4126c019 CC	463
4f86d3a8	464	cpuidle_resume_and_unlock();
4f86d3a8 LB	465	}
	466
	467	EXPORT_SYMBOL_GPL(cpuidle_unregister_device);
	468
1c192d04	469	/**
4c637b21 DL	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
82467a5a	481	for_each_cpu(cpu, drv->cpumask) {
4c637b21 DL	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
82467a5a	513	for_each_cpu(cpu, drv->cpumask) {
4c637b21 DL	514	device = &per_cpu(cpuidle_dev, cpu);
	515	device->cpu = cpu;
	516
	517	#ifdef CONFIG_ARCH_NEEDS_CPU_IDLE_COUPLED
	518	/*
caf4a36e	519	* On multiplatform for ARM, the coupled idle states could be
4c637b21 DL	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
4f86d3a8 LB	540	#ifdef CONFIG_SMP
4f86d3a8 LB	541
4f86d3a8 LB	542	/*
	543	* This function gets called when a part of the kernel has a new latency
	544	* requirement. This means we need to get all processors out of their C-state,
	545	* and then recalculate a new suitable C-state. Just do a cross-cpu IPI; that
	546	* wakes them all right up.
	547	*/
	548	static int cpuidle_latency_notify(struct notifier_block *b,
	549	unsigned long l, void *v)
	550	{
2ed903c5	551	wake_up_all_idle_cpus();
4f86d3a8 LB	552	return NOTIFY_OK;
	553	}
	554
	555	static struct notifier_block cpuidle_latency_notifier = {
	556	.notifier_call = cpuidle_latency_notify,
	557	};
	558
d82b3518 MG	559	static inline void latency_notifier_init(struct notifier_block *n)
	560	{
	561	pm_qos_add_notifier(PM_QOS_CPU_DMA_LATENCY, n);
	562	}
4f86d3a8 LB	563
	564	#else /* CONFIG_SMP */
	565
	566	#define latency_notifier_init(x) do { } while (0)
	567
	568	#endif /* CONFIG_SMP */
	569
	570	/**
	571	* cpuidle_init - core initializer
	572	*/
	573	static int __init cpuidle_init(void)
	574	{
	575	int ret;
	576
62027aea LB	577	if (cpuidle_disabled())
	578	return -ENODEV;
	579
8a25a2fd	580	ret = cpuidle_add_interface(cpu_subsys.dev_root);
4f86d3a8 LB	581	if (ret)
	582	return ret;
	583
	584	latency_notifier_init(&cpuidle_latency_notifier);
	585
	586	return 0;
	587	}
	588
62027aea	589	module_param(off, int, 0444);
4f86d3a8	590	core_initcall(cpuidle_init);