diff options
| -rw-r--r-- | drivers/cpuidle/driver.c | 132 |
1 files changed, 126 insertions, 6 deletions
diff --git a/drivers/cpuidle/driver.c b/drivers/cpuidle/driver.c index e75fa5472a91..3ac499d5a207 100644 --- a/drivers/cpuidle/driver.c +++ b/drivers/cpuidle/driver.c @@ -22,11 +22,26 @@ DEFINE_SPINLOCK(cpuidle_driver_lock); 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; @@ -40,6 +55,15 @@ static inline void __cpuidle_unset_driver(struct cpuidle_driver *drv) } } +/** + * __cpuidle_set_driver - set per CPU driver variables the the given driver. + * @drv: a valid pointer to a struct cpuidle_driver + * + * For each CPU in the driver's cpumask, unset the registered driver per CPU + * to @drv. + * + * Returns 0 on success, -EBUSY if the CPUs have driver(s) already. + */ static inline int __cpuidle_set_driver(struct cpuidle_driver *drv) { int cpu; @@ -61,11 +85,24 @@ static inline int __cpuidle_set_driver(struct cpuidle_driver *drv) 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) @@ -76,6 +113,13 @@ static inline int __cpuidle_set_driver(struct cpuidle_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) @@ -84,21 +128,49 @@ static inline void __cpuidle_unset_driver(struct cpuidle_driver *drv) #endif +/** + * cpuidle_setup_broadcast_timer - enable/disable the broadcast timer + * @arg: a void pointer used to match the SMP cross call API + * + * @arg is used as a value of type 'long' with on of the two values: + * - CLOCK_EVT_NOTIFY_BROADCAST_ON + * - CLOCK_EVT_NOTIFY_BROADCAST_OFF + * + * Set the broadcast timer notification for the current CPU. This function + * is executed per CPU by an SMP cross call. It not supposed to be called + * directly. + */ static void cpuidle_setup_broadcast_timer(void *arg) { int cpu = smp_processor_id(); clockevents_notify((long)(arg), &cpu); } +/** + * __cpuidle_driver_init - initialize the driver's internal data + * @drv: a valid pointer to a struct cpuidle_driver + * + * Returns 0 on success, a negative error code otherwise. + */ static int __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; + /* + * Look for the timer stop flag in the different states, so that we know + * if the broadcast timer has to be set up. The loop is in the reverse + * order, because usually on of the the deeper states has this flag set. + */ for (i = drv->state_count - 1; i >= 0 ; i--) { if (!(drv->states[i].flags & CPUIDLE_FLAG_TIMER_STOP)) @@ -111,6 +183,19 @@ static int __cpuidle_driver_init(struct cpuidle_driver *drv) return 0; } +/** + * __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; @@ -137,8 +222,13 @@ static int __cpuidle_register_driver(struct cpuidle_driver *drv) } /** - * cpuidle_unregister_driver - unregisters a driver - * @drv: the driver + * __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) { @@ -156,7 +246,13 @@ static void __cpuidle_unregister_driver(struct cpuidle_driver *drv) /** * cpuidle_register_driver - registers a driver - * @drv: the 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) { @@ -172,7 +268,11 @@ EXPORT_SYMBOL_GPL(cpuidle_register_driver); /** * cpuidle_unregister_driver - unregisters a driver - * @drv: the 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) { @@ -183,7 +283,9 @@ void cpuidle_unregister_driver(struct cpuidle_driver *drv) EXPORT_SYMBOL_GPL(cpuidle_unregister_driver); /** - * cpuidle_get_driver - return the current 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) { @@ -199,7 +301,11 @@ struct cpuidle_driver *cpuidle_get_driver(void) EXPORT_SYMBOL_GPL(cpuidle_get_driver); /** - * cpuidle_get_cpu_driver - return the driver tied with a cpu + * 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) { @@ -210,6 +316,14 @@ struct cpuidle_driver *cpuidle_get_cpu_driver(struct cpuidle_device *dev) } 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; @@ -223,6 +337,12 @@ struct cpuidle_driver *cpuidle_driver_ref(void) 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 = cpuidle_get_driver(); |