[deliverable/linux.git] / drivers / cpuidle / cpuidle.c

/*
 * cpuidle.c - core cpuidle infrastructure
 *
 * (C) 2006-2007 Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>
 *               Shaohua Li <shaohua.li@intel.com>
 *               Adam Belay <abelay@novell.com>
 *
 * This code is licenced under the GPL.
 */

#include <linux/kernel.h>
#include <linux/mutex.h>
#include <linux/sched.h>
#include <linux/notifier.h>
#include <linux/pm_qos_params.h>
#include <linux/cpu.h>
#include <linux/cpuidle.h>
#include <linux/ktime.h>

#include "cpuidle.h"

DEFINE_PER_CPU(struct cpuidle_device *, cpuidle_devices);

DEFINE_MUTEX(cpuidle_lock);
LIST_HEAD(cpuidle_detected_devices);
static void (*pm_idle_old)(void);

static int enabled_devices;

#if defined(CONFIG_ARCH_HAS_CPU_IDLE_WAIT)
static void cpuidle_kick_cpus(void)
{
	cpu_idle_wait();
}
#elif defined(CONFIG_SMP)
# error "Arch needs cpu_idle_wait() equivalent here"
#else /* !CONFIG_ARCH_HAS_CPU_IDLE_WAIT && !CONFIG_SMP */
static void cpuidle_kick_cpus(void) {}
#endif

static int __cpuidle_register_device(struct cpuidle_device *dev);

/**
 * cpuidle_idle_call - the main idle loop
 *
 * NOTE: no locks or semaphores should be used here
 */
static void cpuidle_idle_call(void)
{
	struct cpuidle_device *dev = __get_cpu_var(cpuidle_devices);
	struct cpuidle_state *target_state;
	int next_state;

	/* check if the device is ready */
	if (!dev || !dev->enabled) {
		if (pm_idle_old)
			pm_idle_old();
		else
			local_irq_enable();
		return;
	}

	/* ask the governor for the next state */
	next_state = cpuidle_curr_governor->select(dev);
	if (need_resched())
		return;
	target_state = &dev->states[next_state];

	/* enter the state and update stats */
	dev->last_residency = target_state->enter(dev, target_state);
	dev->last_state = target_state;
	target_state->time += (unsigned long long)dev->last_residency;
	target_state->usage++;

	/* give the governor an opportunity to reflect on the outcome */
	if (cpuidle_curr_governor->reflect)
		cpuidle_curr_governor->reflect(dev);
}

/**
 * cpuidle_install_idle_handler - installs the cpuidle idle loop handler
 */
void cpuidle_install_idle_handler(void)
{
	if (enabled_devices && (pm_idle != cpuidle_idle_call)) {
		/* Make sure all changes finished before we switch to new idle */
		smp_wmb();
		pm_idle = cpuidle_idle_call;
	}
}

/**
 * cpuidle_uninstall_idle_handler - uninstalls the cpuidle idle loop handler
 */
void cpuidle_uninstall_idle_handler(void)
{
	if (enabled_devices && pm_idle_old && (pm_idle != pm_idle_old)) {
		pm_idle = pm_idle_old;
		cpuidle_kick_cpus();
	}
}

/**
 * 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);

/**
 * 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;

	if (dev->enabled)
		return 0;
	if (!cpuidle_curr_driver || !cpuidle_curr_governor)
		return -EIO;
	if (!dev->state_count)
		return -EINVAL;

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

	if ((ret = cpuidle_add_state_sysfs(dev)))
		return ret;

	if (cpuidle_curr_governor->enable &&
	    (ret = cpuidle_curr_governor->enable(dev)))
		goto fail_sysfs;

	for (i = 0; i < dev->state_count; i++) {
		dev->states[i].usage = 0;
		dev->states[i].time = 0;
	}
	dev->last_residency = 0;
	dev->last_state = NULL;

	smp_wmb();

	dev->enabled = 1;

	enabled_devices++;
	return 0;

fail_sysfs:
	cpuidle_remove_state_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)
{
	if (!dev->enabled)
		return;
	if (!cpuidle_curr_driver || !cpuidle_curr_governor)
		return;

	dev->enabled = 0;

	if (cpuidle_curr_governor->disable)
		cpuidle_curr_governor->disable(dev);

	cpuidle_remove_state_sysfs(dev);
	enabled_devices--;
}

EXPORT_SYMBOL_GPL(cpuidle_disable_device);

#ifdef CONFIG_ARCH_HAS_CPU_RELAX
static int poll_idle(struct cpuidle_device *dev, struct cpuidle_state *st)
{
	ktime_t	t1, t2;
	s64 diff;
	int ret;

	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;

	ret = (int) diff;
	return ret;
}

static void poll_idle_init(struct cpuidle_device *dev)
{
	struct cpuidle_state *state = &dev->states[0];

	cpuidle_set_statedata(state, NULL);

	snprintf(state->name, CPUIDLE_NAME_LEN, "C0");
	snprintf(state->desc, CPUIDLE_DESC_LEN, "CPUIDLE CORE POLL IDLE");
	state->exit_latency = 0;
	state->target_residency = 0;
	state->power_usage = -1;
	state->flags = CPUIDLE_FLAG_POLL;
	state->enter = poll_idle;
}
#else
static void poll_idle_init(struct cpuidle_device *dev) {}
#endif /* CONFIG_ARCH_HAS_CPU_RELAX */

/**
 * __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 sys_device *sys_dev = get_cpu_sysdev((unsigned long)dev->cpu);

	if (!sys_dev)
		return -EINVAL;
	if (!try_module_get(cpuidle_curr_driver->owner))
		return -EINVAL;

	init_completion(&dev->kobj_unregister);

	poll_idle_init(dev);

	per_cpu(cpuidle_devices, dev->cpu) = dev;
	list_add(&dev->device_list, &cpuidle_detected_devices);
	if ((ret = cpuidle_add_sysfs(sys_dev))) {
		module_put(cpuidle_curr_driver->owner);
		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;

	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 sys_device *sys_dev = get_cpu_sysdev((unsigned long)dev->cpu);

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

	cpuidle_pause_and_lock();

	cpuidle_disable_device(dev);

	cpuidle_remove_sysfs(sys_dev);
	list_del(&dev->device_list);
	wait_for_completion(&dev->kobj_unregister);
	per_cpu(cpuidle_devices, dev->cpu) = NULL;

	cpuidle_resume_and_unlock();

	module_put(cpuidle_curr_driver->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;

	pm_idle_old = pm_idle;

	ret = cpuidle_add_class_sysfs(&cpu_sysdev_class);
	if (ret)
		return ret;

	latency_notifier_init(&cpuidle_latency_notifier);

	return 0;
}

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>
d82b3518	15	#include <linux/pm_qos_params.h>
4f86d3a8 LB	16	#include <linux/cpu.h>
4f86d3a8 LB	17	#include <linux/cpuidle.h>
9a0b8415	18	#include <linux/ktime.h>
4f86d3a8 LB	19
	20	#include "cpuidle.h"
	21
	22	DEFINE_PER_CPU(struct cpuidle_device *, cpuidle_devices);
4f86d3a8 LB	23
	24	DEFINE_MUTEX(cpuidle_lock);
	25	LIST_HEAD(cpuidle_detected_devices);
	26	static void (*pm_idle_old)(void);
	27
	28	static int enabled_devices;
	29
a6869cc4 VP	30	#if defined(CONFIG_ARCH_HAS_CPU_IDLE_WAIT)
	31	static void cpuidle_kick_cpus(void)
	32	{
	33	cpu_idle_wait();
	34	}
	35	#elif defined(CONFIG_SMP)
	36	# error "Arch needs cpu_idle_wait() equivalent here"
	37	#else /* !CONFIG_ARCH_HAS_CPU_IDLE_WAIT && !CONFIG_SMP */
	38	static void cpuidle_kick_cpus(void) {}
	39	#endif
	40
dcb84f33 VP	41	static int __cpuidle_register_device(struct cpuidle_device *dev);
dcb84f33 VP	42
4f86d3a8 LB	43	/**
	44	* cpuidle_idle_call - the main idle loop
	45	*
	46	* NOTE: no locks or semaphores should be used here
	47	*/
	48	static void cpuidle_idle_call(void)
	49	{
	50	struct cpuidle_device *dev = __get_cpu_var(cpuidle_devices);
	51	struct cpuidle_state *target_state;
	52	int next_state;
	53
	54	/* check if the device is ready */
	55	if (!dev \|\| !dev->enabled) {
	56	if (pm_idle_old)
	57	pm_idle_old();
	58	else
	59	local_irq_enable();
	60	return;
	61	}
	62
	63	/* ask the governor for the next state */
	64	next_state = cpuidle_curr_governor->select(dev);
	65	if (need_resched())
	66	return;
	67	target_state = &dev->states[next_state];
	68
	69	/* enter the state and update stats */
	70	dev->last_residency = target_state->enter(dev, target_state);
	71	dev->last_state = target_state;
8b78cf60	72	target_state->time += (unsigned long long)dev->last_residency;
4f86d3a8 LB	73	target_state->usage++;
	74
	75	/* give the governor an opportunity to reflect on the outcome */
	76	if (cpuidle_curr_governor->reflect)
	77	cpuidle_curr_governor->reflect(dev);
	78	}
	79
	80	/**
	81	* cpuidle_install_idle_handler - installs the cpuidle idle loop handler
	82	*/
	83	void cpuidle_install_idle_handler(void)
	84	{
	85	if (enabled_devices && (pm_idle != cpuidle_idle_call)) {
	86	/* Make sure all changes finished before we switch to new idle */
	87	smp_wmb();
	88	pm_idle = cpuidle_idle_call;
	89	}
	90	}
	91
	92	/**
	93	* cpuidle_uninstall_idle_handler - uninstalls the cpuidle idle loop handler
	94	*/
	95	void cpuidle_uninstall_idle_handler(void)
	96	{
b032bf70	97	if (enabled_devices && pm_idle_old && (pm_idle != pm_idle_old)) {
4f86d3a8	98	pm_idle = pm_idle_old;
a6869cc4	99	cpuidle_kick_cpus();
4f86d3a8 LB	100	}
	101	}
	102
	103	/**
	104	* cpuidle_pause_and_lock - temporarily disables CPUIDLE
	105	*/
	106	void cpuidle_pause_and_lock(void)
	107	{
	108	mutex_lock(&cpuidle_lock);
	109	cpuidle_uninstall_idle_handler();
	110	}
	111
	112	EXPORT_SYMBOL_GPL(cpuidle_pause_and_lock);
	113
	114	/**
	115	* cpuidle_resume_and_unlock - resumes CPUIDLE operation
	116	*/
	117	void cpuidle_resume_and_unlock(void)
	118	{
	119	cpuidle_install_idle_handler();
	120	mutex_unlock(&cpuidle_lock);
	121	}
	122
	123	EXPORT_SYMBOL_GPL(cpuidle_resume_and_unlock);
	124
	125	/**
	126	* cpuidle_enable_device - enables idle PM for a CPU
	127	* @dev: the CPU
	128	*
	129	* This function must be called between cpuidle_pause_and_lock and
	130	* cpuidle_resume_and_unlock when used externally.
	131	*/
	132	int cpuidle_enable_device(struct cpuidle_device *dev)
	133	{
	134	int ret, i;
	135
	136	if (dev->enabled)
	137	return 0;
	138	if (!cpuidle_curr_driver \|\| !cpuidle_curr_governor)
	139	return -EIO;
	140	if (!dev->state_count)
	141	return -EINVAL;
	142
dcb84f33 VP	143	if (dev->registered == 0) {
	144	ret = __cpuidle_register_device(dev);
	145	if (ret)
	146	return ret;
	147	}
	148
4f86d3a8 LB	149	if ((ret = cpuidle_add_state_sysfs(dev)))
	150	return ret;
	151
	152	if (cpuidle_curr_governor->enable &&
	153	(ret = cpuidle_curr_governor->enable(dev)))
	154	goto fail_sysfs;
	155
	156	for (i = 0; i < dev->state_count; i++) {
	157	dev->states[i].usage = 0;
	158	dev->states[i].time = 0;
	159	}
	160	dev->last_residency = 0;
	161	dev->last_state = NULL;
	162
	163	smp_wmb();
	164
	165	dev->enabled = 1;
	166
	167	enabled_devices++;
	168	return 0;
	169
	170	fail_sysfs:
	171	cpuidle_remove_state_sysfs(dev);
	172
	173	return ret;
	174	}
	175
	176	EXPORT_SYMBOL_GPL(cpuidle_enable_device);
	177
	178	/**
	179	* cpuidle_disable_device - disables idle PM for a CPU
	180	* @dev: the CPU
	181	*
	182	* This function must be called between cpuidle_pause_and_lock and
	183	* cpuidle_resume_and_unlock when used externally.
	184	*/
	185	void cpuidle_disable_device(struct cpuidle_device *dev)
	186	{
	187	if (!dev->enabled)
	188	return;
	189	if (!cpuidle_curr_driver \|\| !cpuidle_curr_governor)
	190	return;
	191
	192	dev->enabled = 0;
	193
	194	if (cpuidle_curr_governor->disable)
	195	cpuidle_curr_governor->disable(dev);
	196
	197	cpuidle_remove_state_sysfs(dev);
	198	enabled_devices--;
	199	}
	200
	201	EXPORT_SYMBOL_GPL(cpuidle_disable_device);
	202
9a0b8415	203	#ifdef CONFIG_ARCH_HAS_CPU_RELAX
	204	static int poll_idle(struct cpuidle_device dev, struct cpuidle_state st)
	205	{
	206	ktime_t t1, t2;
	207	s64 diff;
	208	int ret;
	209
	210	t1 = ktime_get();
	211	local_irq_enable();
	212	while (!need_resched())
	213	cpu_relax();
	214
	215	t2 = ktime_get();
	216	diff = ktime_to_us(ktime_sub(t2, t1));
	217	if (diff > INT_MAX)
	218	diff = INT_MAX;
	219
	220	ret = (int) diff;
	221	return ret;
	222	}
	223
	224	static void poll_idle_init(struct cpuidle_device *dev)
	225	{
	226	struct cpuidle_state *state = &dev->states[0];
	227
	228	cpuidle_set_statedata(state, NULL);
	229
4fcb2fcd VP	230	snprintf(state->name, CPUIDLE_NAME_LEN, "C0");
4fcb2fcd VP	231	snprintf(state->desc, CPUIDLE_DESC_LEN, "CPUIDLE CORE POLL IDLE");
9a0b8415	232	state->exit_latency = 0;
	233	state->target_residency = 0;
	234	state->power_usage = -1;
8e92b660	235	state->flags = CPUIDLE_FLAG_POLL;
9a0b8415	236	state->enter = poll_idle;
	237	}
	238	#else
	239	static void poll_idle_init(struct cpuidle_device *dev) {}
	240	#endif /* CONFIG_ARCH_HAS_CPU_RELAX */
	241
4f86d3a8	242	/**
dcb84f33 VP	243	* __cpuidle_register_device - internal register function called before register
dcb84f33 VP	244	* and enable routines
4f86d3a8	245	* @dev: the cpu
dcb84f33 VP	246	*
dcb84f33 VP	247	* cpuidle_lock mutex must be held before this is called
4f86d3a8	248	*/
dcb84f33	249	static int __cpuidle_register_device(struct cpuidle_device *dev)
4f86d3a8 LB	250	{
	251	int ret;
	252	struct sys_device *sys_dev = get_cpu_sysdev((unsigned long)dev->cpu);
	253
	254	if (!sys_dev)
	255	return -EINVAL;
	256	if (!try_module_get(cpuidle_curr_driver->owner))
	257	return -EINVAL;
	258
	259	init_completion(&dev->kobj_unregister);
	260
9a0b8415	261	poll_idle_init(dev);
9a0b8415	262
4f86d3a8 LB	263	per_cpu(cpuidle_devices, dev->cpu) = dev;
	264	list_add(&dev->device_list, &cpuidle_detected_devices);
	265	if ((ret = cpuidle_add_sysfs(sys_dev))) {
4f86d3a8 LB	266	module_put(cpuidle_curr_driver->owner);
	267	return ret;
	268	}
	269
dcb84f33 VP	270	dev->registered = 1;
	271	return 0;
	272	}
	273
	274	/**
	275	* cpuidle_register_device - registers a CPU's idle PM feature
	276	* @dev: the cpu
	277	*/
	278	int cpuidle_register_device(struct cpuidle_device *dev)
	279	{
	280	int ret;
	281
	282	mutex_lock(&cpuidle_lock);
	283
	284	if ((ret = __cpuidle_register_device(dev))) {
	285	mutex_unlock(&cpuidle_lock);
	286	return ret;
	287	}
	288
4f86d3a8 LB	289	cpuidle_enable_device(dev);
	290	cpuidle_install_idle_handler();
	291
	292	mutex_unlock(&cpuidle_lock);
	293
	294	return 0;
	295
	296	}
	297
	298	EXPORT_SYMBOL_GPL(cpuidle_register_device);
	299
	300	/**
	301	* cpuidle_unregister_device - unregisters a CPU's idle PM feature
	302	* @dev: the cpu
	303	*/
	304	void cpuidle_unregister_device(struct cpuidle_device *dev)
	305	{
	306	struct sys_device *sys_dev = get_cpu_sysdev((unsigned long)dev->cpu);
	307
dcb84f33 VP	308	if (dev->registered == 0)
	309	return;
	310
4f86d3a8 LB	311	cpuidle_pause_and_lock();
	312
	313	cpuidle_disable_device(dev);
	314
	315	cpuidle_remove_sysfs(sys_dev);
	316	list_del(&dev->device_list);
	317	wait_for_completion(&dev->kobj_unregister);
	318	per_cpu(cpuidle_devices, dev->cpu) = NULL;
	319
	320	cpuidle_resume_and_unlock();
	321
	322	module_put(cpuidle_curr_driver->owner);
	323	}
	324
	325	EXPORT_SYMBOL_GPL(cpuidle_unregister_device);
	326
	327	#ifdef CONFIG_SMP
	328
	329	static void smp_callback(void *v)
	330	{
	331	/* we already woke the CPU up, nothing more to do */
	332	}
	333
	334	/*
	335	* This function gets called when a part of the kernel has a new latency
	336	* requirement. This means we need to get all processors out of their C-state,
	337	* and then recalculate a new suitable C-state. Just do a cross-cpu IPI; that
	338	* wakes them all right up.
	339	*/
	340	static int cpuidle_latency_notify(struct notifier_block *b,
	341	unsigned long l, void *v)
	342	{
8691e5a8	343	smp_call_function(smp_callback, NULL, 1);
4f86d3a8 LB	344	return NOTIFY_OK;
	345	}
	346
	347	static struct notifier_block cpuidle_latency_notifier = {
	348	.notifier_call = cpuidle_latency_notify,
	349	};
	350
d82b3518 MG	351	static inline void latency_notifier_init(struct notifier_block *n)
	352	{
	353	pm_qos_add_notifier(PM_QOS_CPU_DMA_LATENCY, n);
	354	}
4f86d3a8 LB	355
	356	#else /* CONFIG_SMP */
	357
	358	#define latency_notifier_init(x) do { } while (0)
	359
	360	#endif /* CONFIG_SMP */
	361
	362	/**
	363	* cpuidle_init - core initializer
	364	*/
	365	static int __init cpuidle_init(void)
	366	{
	367	int ret;
	368
	369	pm_idle_old = pm_idle;
	370
	371	ret = cpuidle_add_class_sysfs(&cpu_sysdev_class);
	372	if (ret)
	373	return ret;
	374
	375	latency_notifier_init(&cpuidle_latency_notifier);
	376
	377	return 0;
	378	}
	379
	380	core_initcall(cpuidle_init);