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387 lines
9.6 KiB
387 lines
9.6 KiB
/* |
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* driver.c - driver support |
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* |
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* (C) 2006-2007 Venkatesh Pallipadi <[email protected]> |
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* Shaohua Li <[email protected]> |
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* Adam Belay <[email protected]> |
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* |
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* This code is licenced under the GPL. |
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*/ |
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#include <linux/mutex.h> |
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#include <linux/module.h> |
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#include <linux/sched.h> |
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#include <linux/sched/idle.h> |
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#include <linux/cpuidle.h> |
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#include <linux/cpumask.h> |
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#include <linux/tick.h> |
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#include <linux/cpu.h> |
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#include "cpuidle.h" |
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DEFINE_SPINLOCK(cpuidle_driver_lock); |
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#ifdef CONFIG_CPU_IDLE_MULTIPLE_DRIVERS |
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static DEFINE_PER_CPU(struct cpuidle_driver *, cpuidle_drivers); |
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/** |
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* __cpuidle_get_cpu_driver - return the cpuidle driver tied to a CPU. |
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* @cpu: the CPU handled by the driver |
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* |
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* Returns a pointer to struct cpuidle_driver or NULL if no driver has been |
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* registered for @cpu. |
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*/ |
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static struct cpuidle_driver *__cpuidle_get_cpu_driver(int cpu) |
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{ |
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return per_cpu(cpuidle_drivers, cpu); |
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} |
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/** |
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* __cpuidle_unset_driver - unset per CPU driver variables. |
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* @drv: a valid pointer to a struct cpuidle_driver |
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* |
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* For each CPU in the driver's CPU mask, unset the registered driver per CPU |
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* variable. If @drv is different from the registered driver, the corresponding |
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* variable is not cleared. |
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*/ |
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static inline void __cpuidle_unset_driver(struct cpuidle_driver *drv) |
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{ |
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int cpu; |
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for_each_cpu(cpu, drv->cpumask) { |
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if (drv != __cpuidle_get_cpu_driver(cpu)) |
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continue; |
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per_cpu(cpuidle_drivers, cpu) = NULL; |
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} |
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} |
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/** |
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* __cpuidle_set_driver - set per CPU driver variables for the given driver. |
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* @drv: a valid pointer to a struct cpuidle_driver |
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* |
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* Returns 0 on success, -EBUSY if any CPU in the cpumask have a driver |
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* different from drv already. |
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*/ |
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static inline int __cpuidle_set_driver(struct cpuidle_driver *drv) |
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{ |
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int cpu; |
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for_each_cpu(cpu, drv->cpumask) { |
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struct cpuidle_driver *old_drv; |
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old_drv = __cpuidle_get_cpu_driver(cpu); |
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if (old_drv && old_drv != drv) |
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return -EBUSY; |
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} |
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for_each_cpu(cpu, drv->cpumask) |
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per_cpu(cpuidle_drivers, cpu) = drv; |
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return 0; |
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} |
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#else |
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static struct cpuidle_driver *cpuidle_curr_driver; |
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/** |
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* __cpuidle_get_cpu_driver - return the global cpuidle driver pointer. |
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* @cpu: ignored without the multiple driver support |
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* |
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* Return a pointer to a struct cpuidle_driver object or NULL if no driver was |
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* previously registered. |
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*/ |
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static inline struct cpuidle_driver *__cpuidle_get_cpu_driver(int cpu) |
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{ |
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return cpuidle_curr_driver; |
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} |
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/** |
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* __cpuidle_set_driver - assign the global cpuidle driver variable. |
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* @drv: pointer to a struct cpuidle_driver object |
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* |
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* Returns 0 on success, -EBUSY if the driver is already registered. |
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*/ |
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static inline int __cpuidle_set_driver(struct cpuidle_driver *drv) |
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{ |
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if (cpuidle_curr_driver) |
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return -EBUSY; |
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cpuidle_curr_driver = drv; |
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return 0; |
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} |
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/** |
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* __cpuidle_unset_driver - unset the global cpuidle driver variable. |
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* @drv: a pointer to a struct cpuidle_driver |
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* |
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* Reset the global cpuidle variable to NULL. If @drv does not match the |
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* registered driver, do nothing. |
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*/ |
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static inline void __cpuidle_unset_driver(struct cpuidle_driver *drv) |
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{ |
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if (drv == cpuidle_curr_driver) |
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cpuidle_curr_driver = NULL; |
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} |
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#endif |
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/** |
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* cpuidle_setup_broadcast_timer - enable/disable the broadcast timer on a cpu |
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* @arg: a void pointer used to match the SMP cross call API |
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* |
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* If @arg is NULL broadcast is disabled otherwise enabled |
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* |
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* This function is executed per CPU by an SMP cross call. It's not |
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* supposed to be called directly. |
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*/ |
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static void cpuidle_setup_broadcast_timer(void *arg) |
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{ |
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if (arg) |
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tick_broadcast_enable(); |
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else |
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tick_broadcast_disable(); |
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} |
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/** |
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* __cpuidle_driver_init - initialize the driver's internal data |
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* @drv: a valid pointer to a struct cpuidle_driver |
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*/ |
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static void __cpuidle_driver_init(struct cpuidle_driver *drv) |
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{ |
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int i; |
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/* |
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* Use all possible CPUs as the default, because if the kernel boots |
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* with some CPUs offline and then we online one of them, the CPU |
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* notifier has to know which driver to assign. |
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*/ |
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if (!drv->cpumask) |
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drv->cpumask = (struct cpumask *)cpu_possible_mask; |
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for (i = 0; i < drv->state_count; i++) { |
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struct cpuidle_state *s = &drv->states[i]; |
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/* |
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* Look for the timer stop flag in the different states and if |
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* it is found, indicate that the broadcast timer has to be set |
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* up. |
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*/ |
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if (s->flags & CPUIDLE_FLAG_TIMER_STOP) |
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drv->bctimer = 1; |
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/* |
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* The core will use the target residency and exit latency |
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* values in nanoseconds, but allow drivers to provide them in |
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* microseconds too. |
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*/ |
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if (s->target_residency > 0) |
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s->target_residency_ns = s->target_residency * NSEC_PER_USEC; |
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else if (s->target_residency_ns < 0) |
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s->target_residency_ns = 0; |
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if (s->exit_latency > 0) |
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s->exit_latency_ns = s->exit_latency * NSEC_PER_USEC; |
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else if (s->exit_latency_ns < 0) |
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s->exit_latency_ns = 0; |
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} |
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} |
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/** |
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* __cpuidle_register_driver: register the driver |
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* @drv: a valid pointer to a struct cpuidle_driver |
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* |
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* Do some sanity checks, initialize the driver, assign the driver to the |
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* global cpuidle driver variable(s) and set up the broadcast timer if the |
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* cpuidle driver has some states that shut down the local timer. |
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* |
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* Returns 0 on success, a negative error code otherwise: |
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* * -EINVAL if the driver pointer is NULL or no idle states are available |
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* * -ENODEV if the cpuidle framework is disabled |
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* * -EBUSY if the driver is already assigned to the global variable(s) |
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*/ |
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static int __cpuidle_register_driver(struct cpuidle_driver *drv) |
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{ |
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int ret; |
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if (!drv || !drv->state_count) |
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return -EINVAL; |
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ret = cpuidle_coupled_state_verify(drv); |
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if (ret) |
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return ret; |
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if (cpuidle_disabled()) |
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return -ENODEV; |
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__cpuidle_driver_init(drv); |
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ret = __cpuidle_set_driver(drv); |
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if (ret) |
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return ret; |
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if (drv->bctimer) |
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on_each_cpu_mask(drv->cpumask, cpuidle_setup_broadcast_timer, |
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(void *)1, 1); |
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return 0; |
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} |
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/** |
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* __cpuidle_unregister_driver - unregister the driver |
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* @drv: a valid pointer to a struct cpuidle_driver |
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* |
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* Check if the driver is no longer in use, reset the global cpuidle driver |
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* variable(s) and disable the timer broadcast notification mechanism if it was |
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* in use. |
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* |
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*/ |
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static void __cpuidle_unregister_driver(struct cpuidle_driver *drv) |
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{ |
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if (drv->bctimer) { |
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drv->bctimer = 0; |
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on_each_cpu_mask(drv->cpumask, cpuidle_setup_broadcast_timer, |
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NULL, 1); |
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} |
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__cpuidle_unset_driver(drv); |
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} |
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/** |
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* cpuidle_register_driver - registers a driver |
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* @drv: a pointer to a valid struct cpuidle_driver |
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* |
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* Register the driver under a lock to prevent concurrent attempts to |
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* [un]register the driver from occuring at the same time. |
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* |
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* Returns 0 on success, a negative error code (returned by |
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* __cpuidle_register_driver()) otherwise. |
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*/ |
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int cpuidle_register_driver(struct cpuidle_driver *drv) |
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{ |
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struct cpuidle_governor *gov; |
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int ret; |
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spin_lock(&cpuidle_driver_lock); |
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ret = __cpuidle_register_driver(drv); |
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spin_unlock(&cpuidle_driver_lock); |
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if (!ret && !strlen(param_governor) && drv->governor && |
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(cpuidle_get_driver() == drv)) { |
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mutex_lock(&cpuidle_lock); |
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gov = cpuidle_find_governor(drv->governor); |
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if (gov) { |
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cpuidle_prev_governor = cpuidle_curr_governor; |
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if (cpuidle_switch_governor(gov) < 0) |
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cpuidle_prev_governor = NULL; |
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} |
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mutex_unlock(&cpuidle_lock); |
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} |
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return ret; |
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} |
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EXPORT_SYMBOL_GPL(cpuidle_register_driver); |
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/** |
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* cpuidle_unregister_driver - unregisters a driver |
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* @drv: a pointer to a valid struct cpuidle_driver |
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* |
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* Unregisters the cpuidle driver under a lock to prevent concurrent attempts |
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* to [un]register the driver from occuring at the same time. @drv has to |
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* match the currently registered driver. |
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*/ |
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void cpuidle_unregister_driver(struct cpuidle_driver *drv) |
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{ |
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bool enabled = (cpuidle_get_driver() == drv); |
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spin_lock(&cpuidle_driver_lock); |
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__cpuidle_unregister_driver(drv); |
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spin_unlock(&cpuidle_driver_lock); |
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if (!enabled) |
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return; |
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mutex_lock(&cpuidle_lock); |
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if (cpuidle_prev_governor) { |
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if (!cpuidle_switch_governor(cpuidle_prev_governor)) |
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cpuidle_prev_governor = NULL; |
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} |
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mutex_unlock(&cpuidle_lock); |
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} |
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EXPORT_SYMBOL_GPL(cpuidle_unregister_driver); |
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/** |
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* cpuidle_get_driver - return the driver tied to the current CPU. |
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* |
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* Returns a struct cpuidle_driver pointer, or NULL if no driver is registered. |
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*/ |
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struct cpuidle_driver *cpuidle_get_driver(void) |
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{ |
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struct cpuidle_driver *drv; |
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int cpu; |
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cpu = get_cpu(); |
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drv = __cpuidle_get_cpu_driver(cpu); |
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put_cpu(); |
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return drv; |
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} |
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EXPORT_SYMBOL_GPL(cpuidle_get_driver); |
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/** |
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* cpuidle_get_cpu_driver - return the driver registered for a CPU. |
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* @dev: a valid pointer to a struct cpuidle_device |
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* |
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* Returns a struct cpuidle_driver pointer, or NULL if no driver is registered |
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* for the CPU associated with @dev. |
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*/ |
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struct cpuidle_driver *cpuidle_get_cpu_driver(struct cpuidle_device *dev) |
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{ |
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if (!dev) |
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return NULL; |
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return __cpuidle_get_cpu_driver(dev->cpu); |
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} |
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EXPORT_SYMBOL_GPL(cpuidle_get_cpu_driver); |
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/** |
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* cpuidle_driver_state_disabled - Disable or enable an idle state |
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* @drv: cpuidle driver owning the state |
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* @idx: State index |
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* @disable: Whether or not to disable the state |
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*/ |
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void cpuidle_driver_state_disabled(struct cpuidle_driver *drv, int idx, |
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bool disable) |
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{ |
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unsigned int cpu; |
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mutex_lock(&cpuidle_lock); |
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spin_lock(&cpuidle_driver_lock); |
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if (!drv->cpumask) { |
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drv->states[idx].flags |= CPUIDLE_FLAG_UNUSABLE; |
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goto unlock; |
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} |
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for_each_cpu(cpu, drv->cpumask) { |
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struct cpuidle_device *dev = per_cpu(cpuidle_devices, cpu); |
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if (!dev) |
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continue; |
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if (disable) |
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dev->states_usage[idx].disable |= CPUIDLE_STATE_DISABLED_BY_DRIVER; |
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else |
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dev->states_usage[idx].disable &= ~CPUIDLE_STATE_DISABLED_BY_DRIVER; |
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} |
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unlock: |
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spin_unlock(&cpuidle_driver_lock); |
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mutex_unlock(&cpuidle_lock); |
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}
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