/* * 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. */ #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt #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 occurring 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 occurring 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);}