[linux-2.6-block.git] / drivers / cpuidle / driver.c

/*
 * driver.c - driver support
 *
 * (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/mutex.h>
#include <linux/module.h>
#include <linux/sched.h>
#include <linux/sched/idle.h>
#include <linux/cpuidle.h>
#include <linux/cpumask.h>
#include <linux/tick.h>
#include <linux/cpu.h>
#include <linux/math64.h>

#include "cpuidle.h"

DEFINE_SPINLOCK(cpuidle_driver_lock);

#ifdef CONFIG_CPU_IDLE_MULTIPLE_DRIVERS

static DEFINE_PER_CPU(struct cpuidle_driver *, cpuidle_drivers);

/**
 * __cpuidle_get_cpu_driver - return the cpuidle driver tied to a CPU.
 * @cpu: the CPU handled by the driver
 *
 * Returns a pointer to struct cpuidle_driver or NULL if no driver has been
 * registered for @cpu.
 */
static struct cpuidle_driver *__cpuidle_get_cpu_driver(int cpu)
{
	return per_cpu(cpuidle_drivers, cpu);
}

/**
 * __cpuidle_unset_driver - unset per CPU driver variables.
 * @drv: a valid pointer to a struct cpuidle_driver
 *
 * For each CPU in the driver's CPU mask, unset the registered driver per CPU
 * variable. If @drv is different from the registered driver, the corresponding
 * variable is not cleared.
 */
static inline void __cpuidle_unset_driver(struct cpuidle_driver *drv)
{
	int cpu;

	for_each_cpu(cpu, drv->cpumask) {

		if (drv != __cpuidle_get_cpu_driver(cpu))
			continue;

		per_cpu(cpuidle_drivers, cpu) = NULL;
	}
}

/**
 * __cpuidle_set_driver - set per CPU driver variables for the given driver.
 * @drv: a valid pointer to a struct cpuidle_driver
 *
 * Returns 0 on success, -EBUSY if any CPU in the cpumask have a driver
 * different from drv already.
 */
static inline int __cpuidle_set_driver(struct cpuidle_driver *drv)
{
	int cpu;

	for_each_cpu(cpu, drv->cpumask) {
		struct cpuidle_driver *old_drv;

		old_drv = __cpuidle_get_cpu_driver(cpu);
		if (old_drv && old_drv != drv)
			return -EBUSY;
	}

	for_each_cpu(cpu, drv->cpumask)
		per_cpu(cpuidle_drivers, cpu) = drv;

	return 0;
}

#else

static struct cpuidle_driver *cpuidle_curr_driver;

/**
 * __cpuidle_get_cpu_driver - return the global cpuidle driver pointer.
 * @cpu: ignored without the multiple driver support
 *
 * Return a pointer to a struct cpuidle_driver object or NULL if no driver was
 * previously registered.
 */
static inline struct cpuidle_driver *__cpuidle_get_cpu_driver(int cpu)
{
	return cpuidle_curr_driver;
}

/**
 * __cpuidle_set_driver - assign the global cpuidle driver variable.
 * @drv: pointer to a struct cpuidle_driver object
 *
 * Returns 0 on success, -EBUSY if the driver is already registered.
 */
static inline int __cpuidle_set_driver(struct cpuidle_driver *drv)
{
	if (cpuidle_curr_driver)
		return -EBUSY;

	cpuidle_curr_driver = drv;

	return 0;
}

/**
 * __cpuidle_unset_driver - unset the global cpuidle driver variable.
 * @drv: a pointer to a struct cpuidle_driver
 *
 * Reset the global cpuidle variable to NULL.  If @drv does not match the
 * registered driver, do nothing.
 */
static inline void __cpuidle_unset_driver(struct cpuidle_driver *drv)
{
	if (drv == cpuidle_curr_driver)
		cpuidle_curr_driver = NULL;
}

#endif

/**
 * cpuidle_setup_broadcast_timer - enable/disable the broadcast timer on a cpu
 * @arg: a void pointer used to match the SMP cross call API
 *
 * If @arg is NULL broadcast is disabled otherwise enabled
 *
 * This function is executed per CPU by an SMP cross call.  It's not
 * supposed to be called directly.
 */
static void cpuidle_setup_broadcast_timer(void *arg)
{
	if (arg)
		tick_broadcast_enable();
	else
		tick_broadcast_disable();
}

/**
 * __cpuidle_driver_init - initialize the driver's internal data
 * @drv: a valid pointer to a struct cpuidle_driver
 */
static void __cpuidle_driver_init(struct cpuidle_driver *drv)
{
	int i;

	/*
	 * Use all possible CPUs as the default, because if the kernel boots
	 * with some CPUs offline and then we online one of them, the CPU
	 * notifier has to know which driver to assign.
	 */
	if (!drv->cpumask)
		drv->cpumask = (struct cpumask *)cpu_possible_mask;

	for (i = 0; i < drv->state_count; i++) {
		struct cpuidle_state *s = &drv->states[i];

		/*
		 * Look for the timer stop flag in the different states and if
		 * it is found, indicate that the broadcast timer has to be set
		 * up.
		 */
		if (s->flags & CPUIDLE_FLAG_TIMER_STOP)
			drv->bctimer = 1;

		/*
		 * The core will use the target residency and exit latency
		 * values in nanoseconds, but allow drivers to provide them in
		 * microseconds too.
		 */
		if (s->target_residency > 0)
			s->target_residency_ns = s->target_residency * NSEC_PER_USEC;
		else if (s->target_residency_ns < 0)
			s->target_residency_ns = 0;
		else
			s->target_residency = div_u64(s->target_residency_ns, NSEC_PER_USEC);

		if (s->exit_latency > 0)
			s->exit_latency_ns = mul_u32_u32(s->exit_latency, NSEC_PER_USEC);
		else if (s->exit_latency_ns < 0)
			s->exit_latency_ns =  0;
		else
			s->exit_latency = div_u64(s->exit_latency_ns, NSEC_PER_USEC);
	}
}

/**
 * __cpuidle_register_driver: register the driver
 * @drv: a valid pointer to a struct cpuidle_driver
 *
 * Do some sanity checks, initialize the driver, assign the driver to the
 * global cpuidle driver variable(s) and set up the broadcast timer if the
 * cpuidle driver has some states that shut down the local timer.
 *
 * Returns 0 on success, a negative error code otherwise:
 *  * -EINVAL if the driver pointer is NULL or no idle states are available
 *  * -ENODEV if the cpuidle framework is disabled
 *  * -EBUSY if the driver is already assigned to the global variable(s)
 */
static int __cpuidle_register_driver(struct cpuidle_driver *drv)
{
	int ret;

	if (!drv || !drv->state_count)
		return -EINVAL;

	ret = cpuidle_coupled_state_verify(drv);
	if (ret)
		return ret;

	if (cpuidle_disabled())
		return -ENODEV;

	__cpuidle_driver_init(drv);

	ret = __cpuidle_set_driver(drv);
	if (ret)
		return ret;

	if (drv->bctimer)
		on_each_cpu_mask(drv->cpumask, cpuidle_setup_broadcast_timer,
				 (void *)1, 1);

	return 0;
}

/**
 * __cpuidle_unregister_driver - unregister the driver
 * @drv: a valid pointer to a struct cpuidle_driver
 *
 * Check if the driver is no longer in use, reset the global cpuidle driver
 * variable(s) and disable the timer broadcast notification mechanism if it was
 * in use.
 *
 */
static void __cpuidle_unregister_driver(struct cpuidle_driver *drv)
{
	if (drv->bctimer) {
		drv->bctimer = 0;
		on_each_cpu_mask(drv->cpumask, cpuidle_setup_broadcast_timer,
				 NULL, 1);
	}

	__cpuidle_unset_driver(drv);
}

/**
 * cpuidle_register_driver - registers a driver
 * @drv: a pointer to a valid struct cpuidle_driver
 *
 * Register the driver under a lock to prevent concurrent attempts to
 * [un]register the driver from occuring at the same time.
 *
 * Returns 0 on success, a negative error code (returned by
 * __cpuidle_register_driver()) otherwise.
 */
int cpuidle_register_driver(struct cpuidle_driver *drv)
{
	struct cpuidle_governor *gov;
	int ret;

	spin_lock(&cpuidle_driver_lock);
	ret = __cpuidle_register_driver(drv);
	spin_unlock(&cpuidle_driver_lock);

	if (!ret && !strlen(param_governor) && drv->governor &&
	    (cpuidle_get_driver() == drv)) {
		mutex_lock(&cpuidle_lock);
		gov = cpuidle_find_governor(drv->governor);
		if (gov) {
			cpuidle_prev_governor = cpuidle_curr_governor;
			if (cpuidle_switch_governor(gov) < 0)
				cpuidle_prev_governor = NULL;
		}
		mutex_unlock(&cpuidle_lock);
	}

	return ret;
}
EXPORT_SYMBOL_GPL(cpuidle_register_driver);

/**
 * cpuidle_unregister_driver - unregisters a driver
 * @drv: a pointer to a valid struct cpuidle_driver
 *
 * Unregisters the cpuidle driver under a lock to prevent concurrent attempts
 * to [un]register the driver from occuring at the same time.  @drv has to
 * match the currently registered driver.
 */
void cpuidle_unregister_driver(struct cpuidle_driver *drv)
{
	bool enabled = (cpuidle_get_driver() == drv);

	spin_lock(&cpuidle_driver_lock);
	__cpuidle_unregister_driver(drv);
	spin_unlock(&cpuidle_driver_lock);

	if (!enabled)
		return;

	mutex_lock(&cpuidle_lock);
	if (cpuidle_prev_governor) {
		if (!cpuidle_switch_governor(cpuidle_prev_governor))
			cpuidle_prev_governor = NULL;
	}
	mutex_unlock(&cpuidle_lock);
}
EXPORT_SYMBOL_GPL(cpuidle_unregister_driver);

/**
 * cpuidle_get_driver - return the driver tied to the current CPU.
 *
 * Returns a struct cpuidle_driver pointer, or NULL if no driver is registered.
 */
struct cpuidle_driver *cpuidle_get_driver(void)
{
	struct cpuidle_driver *drv;
	int cpu;

	cpu = get_cpu();
	drv = __cpuidle_get_cpu_driver(cpu);
	put_cpu();

	return drv;
}
EXPORT_SYMBOL_GPL(cpuidle_get_driver);

/**
 * cpuidle_get_cpu_driver - return the driver registered for a CPU.
 * @dev: a valid pointer to a struct cpuidle_device
 *
 * Returns a struct cpuidle_driver pointer, or NULL if no driver is registered
 * for the CPU associated with @dev.
 */
struct cpuidle_driver *cpuidle_get_cpu_driver(struct cpuidle_device *dev)
{
	if (!dev)
		return NULL;

	return __cpuidle_get_cpu_driver(dev->cpu);
}
EXPORT_SYMBOL_GPL(cpuidle_get_cpu_driver);

/**
 * cpuidle_driver_state_disabled - Disable or enable an idle state
 * @drv: cpuidle driver owning the state
 * @idx: State index
 * @disable: Whether or not to disable the state
 */
void cpuidle_driver_state_disabled(struct cpuidle_driver *drv, int idx,
				 bool disable)
{
	unsigned int cpu;

	mutex_lock(&cpuidle_lock);

	spin_lock(&cpuidle_driver_lock);

	if (!drv->cpumask) {
		drv->states[idx].flags |= CPUIDLE_FLAG_UNUSABLE;
		goto unlock;
	}

	for_each_cpu(cpu, drv->cpumask) {
		struct cpuidle_device *dev = per_cpu(cpuidle_devices, cpu);

		if (!dev)
			continue;

		if (disable)
			dev->states_usage[idx].disable |= CPUIDLE_STATE_DISABLED_BY_DRIVER;
		else
			dev->states_usage[idx].disable &= ~CPUIDLE_STATE_DISABLED_BY_DRIVER;
	}

unlock:
	spin_unlock(&cpuidle_driver_lock);

	mutex_unlock(&cpuidle_lock);
}
Commit	Line	Data
4f86d3a8 LB	1	/*
	2	* driver.c - driver support
	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/mutex.h>
	12	#include <linux/module.h>
d7c7f103	13	#include <linux/sched.h>
4c822698	14	#include <linux/sched/idle.h>
4f86d3a8	15	#include <linux/cpuidle.h>
a06df062	16	#include <linux/cpumask.h>
ee7a1438	17	#include <linux/tick.h>
6727ad9e	18	#include <linux/cpu.h>
88390dd7	19	#include <linux/math64.h>
4f86d3a8 LB	20
	21	#include "cpuidle.h"
	22
4f86d3a8 LB	23	DEFINE_SPINLOCK(cpuidle_driver_lock);
4f86d3a8 LB	24
82467a5a	25	#ifdef CONFIG_CPU_IDLE_MULTIPLE_DRIVERS
bf4d1b5d	26
82467a5a DL	27	static DEFINE_PER_CPU(struct cpuidle_driver *, cpuidle_drivers);
82467a5a DL	28
6d19cb93 DL	29	/**
	30	* __cpuidle_get_cpu_driver - return the cpuidle driver tied to a CPU.
	31	* @cpu: the CPU handled by the driver
	32	*
	33	* Returns a pointer to struct cpuidle_driver or NULL if no driver has been
	34	* registered for @cpu.
	35	*/
82467a5a	36	static struct cpuidle_driver *__cpuidle_get_cpu_driver(int cpu)
13dd52f1	37	{
82467a5a	38	return per_cpu(cpuidle_drivers, cpu);
a06df062 DL	39	}
a06df062 DL	40
6d19cb93 DL	41	/**
	42	* __cpuidle_unset_driver - unset per CPU driver variables.
	43	* @drv: a valid pointer to a struct cpuidle_driver
	44	*
	45	* For each CPU in the driver's CPU mask, unset the registered driver per CPU
	46	* variable. If @drv is different from the registered driver, the corresponding
	47	* variable is not cleared.
	48	*/
82467a5a	49	static inline void __cpuidle_unset_driver(struct cpuidle_driver *drv)
a06df062	50	{
82467a5a	51	int cpu;
a06df062	52
82467a5a	53	for_each_cpu(cpu, drv->cpumask) {
a06df062	54
82467a5a	55	if (drv != __cpuidle_get_cpu_driver(cpu))
a06df062 DL	56	continue;
a06df062 DL	57
82467a5a	58	per_cpu(cpuidle_drivers, cpu) = NULL;
a06df062	59	}
13dd52f1 DL	60	}
13dd52f1 DL	61
6d19cb93	62	/**
caf4a36e	63	* __cpuidle_set_driver - set per CPU driver variables for the given driver.
6d19cb93 DL	64	* @drv: a valid pointer to a struct cpuidle_driver
6d19cb93 DL	65	*
918c1fe9 ZD	66	* Returns 0 on success, -EBUSY if any CPU in the cpumask have a driver
918c1fe9 ZD	67	* different from drv already.
6d19cb93	68	*/
82467a5a	69	static inline int __cpuidle_set_driver(struct cpuidle_driver *drv)
4f86d3a8	70	{
82467a5a	71	int cpu;
62027aea	72
82467a5a	73	for_each_cpu(cpu, drv->cpumask) {
918c1fe9	74	struct cpuidle_driver *old_drv;
ed953472	75
918c1fe9 ZD	76	old_drv = __cpuidle_get_cpu_driver(cpu);
918c1fe9 ZD	77	if (old_drv && old_drv != drv)
82467a5a	78	return -EBUSY;
918c1fe9	79	}
ed953472	80
918c1fe9	81	for_each_cpu(cpu, drv->cpumask)
82467a5a	82	per_cpu(cpuidle_drivers, cpu) = drv;
42f67f2a	83
13dd52f1 DL	84	return 0;
	85	}
	86
82467a5a	87	#else
13dd52f1	88
82467a5a	89	static struct cpuidle_driver *cpuidle_curr_driver;
a06df062	90
6d19cb93 DL	91	/**
	92	* __cpuidle_get_cpu_driver - return the global cpuidle driver pointer.
	93	* @cpu: ignored without the multiple driver support
	94	*
	95	* Return a pointer to a struct cpuidle_driver object or NULL if no driver was
	96	* previously registered.
	97	*/
82467a5a DL	98	static inline struct cpuidle_driver *__cpuidle_get_cpu_driver(int cpu)
	99	{
	100	return cpuidle_curr_driver;
bf4d1b5d DL	101	}
bf4d1b5d DL	102
6d19cb93 DL	103	/**
	104	* __cpuidle_set_driver - assign the global cpuidle driver variable.
	105	* @drv: pointer to a struct cpuidle_driver object
	106	*
	107	* Returns 0 on success, -EBUSY if the driver is already registered.
	108	*/
82467a5a DL	109	static inline int __cpuidle_set_driver(struct cpuidle_driver *drv)
	110	{
	111	if (cpuidle_curr_driver)
	112	return -EBUSY;
bf4d1b5d	113
82467a5a	114	cpuidle_curr_driver = drv;
bf4d1b5d	115
82467a5a	116	return 0;
bf4d1b5d DL	117	}
bf4d1b5d DL	118
6d19cb93 DL	119	/**
	120	* __cpuidle_unset_driver - unset the global cpuidle driver variable.
	121	* @drv: a pointer to a struct cpuidle_driver
	122	*
	123	* Reset the global cpuidle variable to NULL. If @drv does not match the
	124	* registered driver, do nothing.
	125	*/
82467a5a	126	static inline void __cpuidle_unset_driver(struct cpuidle_driver *drv)
bf4d1b5d	127	{
82467a5a DL	128	if (drv == cpuidle_curr_driver)
82467a5a DL	129	cpuidle_curr_driver = NULL;
bf4d1b5d DL	130	}
bf4d1b5d DL	131
82467a5a DL	132	#endif
82467a5a DL	133
6d19cb93	134	/**
ee7a1438	135	* cpuidle_setup_broadcast_timer - enable/disable the broadcast timer on a cpu
6d19cb93 DL	136	* @arg: a void pointer used to match the SMP cross call API
6d19cb93 DL	137	*
ee7a1438	138	* If @arg is NULL broadcast is disabled otherwise enabled
6d19cb93	139	*
ee7a1438 TG	140	* This function is executed per CPU by an SMP cross call. It's not
ee7a1438 TG	141	* supposed to be called directly.
6d19cb93	142	*/
82467a5a	143	static void cpuidle_setup_broadcast_timer(void *arg)
bf4d1b5d	144	{
ee7a1438 TG	145	if (arg)
	146	tick_broadcast_enable();
	147	else
	148	tick_broadcast_disable();
bf4d1b5d DL	149	}
bf4d1b5d DL	150
6d19cb93 DL	151	/**
	152	* __cpuidle_driver_init - initialize the driver's internal data
	153	* @drv: a valid pointer to a struct cpuidle_driver
6d19cb93	154	*/
e437f3e3	155	static void __cpuidle_driver_init(struct cpuidle_driver *drv)
bf4d1b5d	156	{
82467a5a	157	int i;
bf4d1b5d	158
6d19cb93 DL	159	/*
	160	* Use all possible CPUs as the default, because if the kernel boots
	161	* with some CPUs offline and then we online one of them, the CPU
	162	* notifier has to know which driver to assign.
	163	*/
82467a5a DL	164	if (!drv->cpumask)
82467a5a DL	165	drv->cpumask = (struct cpumask *)cpu_possible_mask;
bf4d1b5d	166
c1d51f68 RW	167	for (i = 0; i < drv->state_count; i++) {
	168	struct cpuidle_state *s = &drv->states[i];
	169
	170	/*
	171	* Look for the timer stop flag in the different states and if
	172	* it is found, indicate that the broadcast timer has to be set
	173	* up.
	174	*/
	175	if (s->flags & CPUIDLE_FLAG_TIMER_STOP)
b171a856	176	drv->bctimer = 1;
c1d51f68 RW	177
	178	/*
	179	* The core will use the target residency and exit latency
	180	* values in nanoseconds, but allow drivers to provide them in
	181	* microseconds too.
	182	*/
	183	if (s->target_residency > 0)
	184	s->target_residency_ns = s->target_residency * NSEC_PER_USEC;
2ab80d46 RW	185	else if (s->target_residency_ns < 0)
2ab80d46 RW	186	s->target_residency_ns = 0;
41204a60 RW	187	else
41204a60 RW	188	s->target_residency = div_u64(s->target_residency_ns, NSEC_PER_USEC);
c1d51f68 RW	189
c1d51f68 RW	190	if (s->exit_latency > 0)
88390dd7	191	s->exit_latency_ns = mul_u32_u32(s->exit_latency, NSEC_PER_USEC);
2ab80d46 RW	192	else if (s->exit_latency_ns < 0)
2ab80d46 RW	193	s->exit_latency_ns = 0;
41204a60 RW	194	else
41204a60 RW	195	s->exit_latency = div_u64(s->exit_latency_ns, NSEC_PER_USEC);
82467a5a	196	}
bf4d1b5d DL	197	}
bf4d1b5d DL	198
6d19cb93 DL	199	/**
	200	* __cpuidle_register_driver: register the driver
	201	* @drv: a valid pointer to a struct cpuidle_driver
	202	*
	203	* Do some sanity checks, initialize the driver, assign the driver to the
	204	* global cpuidle driver variable(s) and set up the broadcast timer if the
	205	* cpuidle driver has some states that shut down the local timer.
	206	*
	207	* Returns 0 on success, a negative error code otherwise:
	208	* * -EINVAL if the driver pointer is NULL or no idle states are available
	209	* * -ENODEV if the cpuidle framework is disabled
	210	* * -EBUSY if the driver is already assigned to the global variable(s)
	211	*/
82467a5a	212	static int __cpuidle_register_driver(struct cpuidle_driver *drv)
bf4d1b5d DL	213	{
	214	int ret;
	215
82467a5a DL	216	if (!drv \|\| !drv->state_count)
82467a5a DL	217	return -EINVAL;
bf4d1b5d	218
abceaa9c XP	219	ret = cpuidle_coupled_state_verify(drv);
	220	if (ret)
	221	return ret;
	222
82467a5a DL	223	if (cpuidle_disabled())
82467a5a DL	224	return -ENODEV;
bf4d1b5d	225
e437f3e3	226	__cpuidle_driver_init(drv);
ed953472	227
82467a5a DL	228	ret = __cpuidle_set_driver(drv);
	229	if (ret)
	230	return ret;
13dd52f1	231
82467a5a DL	232	if (drv->bctimer)
82467a5a DL	233	on_each_cpu_mask(drv->cpumask, cpuidle_setup_broadcast_timer,
ee7a1438	234	(void *)1, 1);
4f86d3a8	235
82467a5a	236	return 0;
4f86d3a8	237	}
4f86d3a8	238
752138df	239	/**
6d19cb93 DL	240	* __cpuidle_unregister_driver - unregister the driver
	241	* @drv: a valid pointer to a struct cpuidle_driver
	242	*
	243	* Check if the driver is no longer in use, reset the global cpuidle driver
	244	* variable(s) and disable the timer broadcast notification mechanism if it was
	245	* in use.
	246	*
752138df	247	*/
82467a5a	248	static void __cpuidle_unregister_driver(struct cpuidle_driver *drv)
bf4d1b5d	249	{
82467a5a DL	250	if (drv->bctimer) {
	251	drv->bctimer = 0;
	252	on_each_cpu_mask(drv->cpumask, cpuidle_setup_broadcast_timer,
ee7a1438	253	NULL, 1);
82467a5a	254	}
bf4d1b5d	255
82467a5a	256	__cpuidle_unset_driver(drv);
752138df	257	}
bf4d1b5d DL	258
	259	/**
	260	* cpuidle_register_driver - registers a driver
6d19cb93 DL	261	* @drv: a pointer to a valid struct cpuidle_driver
	262	*
	263	* Register the driver under a lock to prevent concurrent attempts to
	264	* [un]register the driver from occuring at the same time.
	265	*
	266	* Returns 0 on success, a negative error code (returned by
	267	* __cpuidle_register_driver()) otherwise.
bf4d1b5d DL	268	*/
	269	int cpuidle_register_driver(struct cpuidle_driver *drv)
	270	{
cb5d8c45	271	struct cpuidle_governor *gov;
82467a5a	272	int ret;
bf4d1b5d	273
bf4d1b5d	274	spin_lock(&cpuidle_driver_lock);
82467a5a	275	ret = __cpuidle_register_driver(drv);
bf4d1b5d	276	spin_unlock(&cpuidle_driver_lock);
bf4d1b5d	277
cb5d8c45 JM	278	if (!ret && !strlen(param_governor) && drv->governor &&
	279	(cpuidle_get_driver() == drv)) {
	280	mutex_lock(&cpuidle_lock);
	281	gov = cpuidle_find_governor(drv->governor);
	282	if (gov) {
	283	cpuidle_prev_governor = cpuidle_curr_governor;
	284	if (cpuidle_switch_governor(gov) < 0)
	285	cpuidle_prev_governor = NULL;
	286	}
	287	mutex_unlock(&cpuidle_lock);
	288	}
	289
bf4d1b5d DL	290	return ret;
	291	}
	292	EXPORT_SYMBOL_GPL(cpuidle_register_driver);
752138df	293
4f86d3a8 LB	294	/**
4f86d3a8 LB	295	* cpuidle_unregister_driver - unregisters a driver
6d19cb93 DL	296	* @drv: a pointer to a valid struct cpuidle_driver
	297	*
	298	* Unregisters the cpuidle driver under a lock to prevent concurrent attempts
	299	* to [un]register the driver from occuring at the same time. @drv has to
	300	* match the currently registered driver.
4f86d3a8 LB	301	*/
	302	void cpuidle_unregister_driver(struct cpuidle_driver *drv)
	303	{
cb5d8c45 JM	304	bool enabled = (cpuidle_get_driver() == drv);
cb5d8c45 JM	305
4f86d3a8	306	spin_lock(&cpuidle_driver_lock);
82467a5a	307	__cpuidle_unregister_driver(drv);
4f86d3a8	308	spin_unlock(&cpuidle_driver_lock);
cb5d8c45 JM	309
	310	if (!enabled)
	311	return;
	312
	313	mutex_lock(&cpuidle_lock);
	314	if (cpuidle_prev_governor) {
	315	if (!cpuidle_switch_governor(cpuidle_prev_governor))
	316	cpuidle_prev_governor = NULL;
	317	}
	318	mutex_unlock(&cpuidle_lock);
4f86d3a8	319	}
4f86d3a8	320	EXPORT_SYMBOL_GPL(cpuidle_unregister_driver);
bf4d1b5d DL	321
bf4d1b5d DL	322	/**
6d19cb93 DL	323	* cpuidle_get_driver - return the driver tied to the current CPU.
	324	*
	325	* Returns a struct cpuidle_driver pointer, or NULL if no driver is registered.
bf4d1b5d DL	326	*/
	327	struct cpuidle_driver *cpuidle_get_driver(void)
	328	{
	329	struct cpuidle_driver *drv;
	330	int cpu;
	331
	332	cpu = get_cpu();
	333	drv = __cpuidle_get_cpu_driver(cpu);
	334	put_cpu();
	335
	336	return drv;
	337	}
	338	EXPORT_SYMBOL_GPL(cpuidle_get_driver);
	339
	340	/**
6d19cb93 DL	341	* cpuidle_get_cpu_driver - return the driver registered for a CPU.
	342	* @dev: a valid pointer to a struct cpuidle_device
	343	*
	344	* Returns a struct cpuidle_driver pointer, or NULL if no driver is registered
	345	* for the CPU associated with @dev.
bf4d1b5d DL	346	*/
	347	struct cpuidle_driver cpuidle_get_cpu_driver(struct cpuidle_device dev)
	348	{
bf4d1b5d DL	349	if (!dev)
	350	return NULL;
	351
ac34d7c8	352	return __cpuidle_get_cpu_driver(dev->cpu);
bf4d1b5d DL	353	}
bf4d1b5d DL	354	EXPORT_SYMBOL_GPL(cpuidle_get_cpu_driver);
6e797a07	355
cbda56d5 RW	356	/**
	357	* cpuidle_driver_state_disabled - Disable or enable an idle state
	358	* @drv: cpuidle driver owning the state
	359	* @idx: State index
	360	* @disable: Whether or not to disable the state
	361	*/
	362	void cpuidle_driver_state_disabled(struct cpuidle_driver *drv, int idx,
	363	bool disable)
	364	{
	365	unsigned int cpu;
	366
	367	mutex_lock(&cpuidle_lock);
	368
b0142d66 RW	369	spin_lock(&cpuidle_driver_lock);
	370
	371	if (!drv->cpumask) {
	372	drv->states[idx].flags \|= CPUIDLE_FLAG_UNUSABLE;
	373	goto unlock;
	374	}
	375
cbda56d5 RW	376	for_each_cpu(cpu, drv->cpumask) {
	377	struct cpuidle_device *dev = per_cpu(cpuidle_devices, cpu);
	378
	379	if (!dev)
	380	continue;
	381
	382	if (disable)
	383	dev->states_usage[idx].disable \|= CPUIDLE_STATE_DISABLED_BY_DRIVER;
	384	else
	385	dev->states_usage[idx].disable &= ~CPUIDLE_STATE_DISABLED_BY_DRIVER;
	386	}
	387
b0142d66 RW	388	unlock:
	389	spin_unlock(&cpuidle_driver_lock);
	390
cbda56d5 RW	391	mutex_unlock(&cpuidle_lock);
cbda56d5 RW	392	}