drivers/cpuidle/driver.c - linux - Git at Google

 /*
  * 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);
 }
 EXPORT_SYMBOL_GPL(cpuidle_driver_state_disabled);
	/*
	* 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);
	}
	EXPORT_SYMBOL_GPL(cpuidle_driver_state_disabled);