| /* |
| * 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; |
| |
| drv->refcnt = 0; |
| |
| /* |
| * 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 (WARN_ON(drv->refcnt > 0)) |
| return; |
| |
| 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_ref - get a reference to the driver. |
| * |
| * Increment the reference counter of the cpuidle driver associated with |
| * the current CPU. |
| * |
| * Returns a pointer to the driver, or NULL if the current CPU has no driver. |
| */ |
| struct cpuidle_driver *cpuidle_driver_ref(void) |
| { |
| struct cpuidle_driver *drv; |
| |
| spin_lock(&cpuidle_driver_lock); |
| |
| drv = cpuidle_get_driver(); |
| if (drv) |
| drv->refcnt++; |
| |
| spin_unlock(&cpuidle_driver_lock); |
| return drv; |
| } |
| |
| /** |
| * cpuidle_driver_unref - puts down the refcount for the driver |
| * |
| * Decrement the reference counter of the cpuidle driver associated with |
| * the current CPU. |
| */ |
| void cpuidle_driver_unref(void) |
| { |
| struct cpuidle_driver *drv; |
| |
| spin_lock(&cpuidle_driver_lock); |
| |
| drv = cpuidle_get_driver(); |
| if (drv && !WARN_ON(drv->refcnt <= 0)) |
| drv->refcnt--; |
| |
| spin_unlock(&cpuidle_driver_lock); |
| } |
| |
| /** |
| * 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); |
| |
| 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; |
| } |
| |
| mutex_unlock(&cpuidle_lock); |
| } |