[mirror_ubuntu-hirsute-kernel.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 "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;

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