Added kerneldoc and comments for the cpuidle framework driver's code.
Signed-off-by: Daniel Lezcano daniel.lezcano@linaro.org --- [V4] - fixed kerneldoc comment format
drivers/cpuidle/driver.c | 134 +++++++++++++++++++++++++++++++++++++++++++--- 1 file changed, 128 insertions(+), 6 deletions(-)
diff --git a/drivers/cpuidle/driver.c b/drivers/cpuidle/driver.c index e75fa54..4cc5bc4 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 - returns the cpuidle driver tied with a cpu + * @cpu: the cpu handled by the driver + * + * Returns a pointer to struct cpuidle_driver, NULL if no driver has been + * registered for this driver + */ static struct cpuidle_driver *__cpuidle_get_cpu_driver(int cpu) { return per_cpu(cpuidle_drivers, cpu); }
+/** + * __cpuidle_unset_driver - set the per cpu variable driver to NULL. + * @drv: a valid pointer to a struct cpuidle_driver + * + * For each cpu belonging to the driver's cpu mask, set the registered + * driver to NULL. If the specified driver is different from the registered + * one, the registered driver is untouched. + */ 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 - assign to the per cpu variable the driver pointer + * @drv: a valid pointer to a struct cpuidle_driver + * + * For each cpus handled by the driver, belonging to the driver's cpumask, + * assign to the per cpu variable the driver pointer + * + * Returns 0 on success, -EBUSY if a driver was already assigned to a cpu. + */ 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 - returns the global cpuidle driver pointer. + * @cpu: this parameter is ignored without the multiple driver support + * + * Returns a pointer to a struct cpuidle_driver, 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: a pointer to a struct cpuidle_driver + * + * 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 - reset the global cpuidle driver variable + * @drv: a pointer to a struct cpuidle_driver + * + * Sets the global cpuidle variable to NULL, if the specified driver + * does not match the registered driver, the function will have no effect. + */ 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, actually used to match the smp cross call api but used + * as a long with two values: + * - CLOCK_EVT_NOTIFY_BROADCAST_ON + * - CLOCK_EVT_NOTIFY_BROADCAST_OFF + * + * Sets the broadcast timer notification for the current cpu. This function + * is called per cpu context invoked by a 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 otherwise. + */ static int __cpuidle_driver_init(struct cpuidle_driver *drv) { int i;
drv->refcnt = 0;
+ /* + * we default here to all cpu possible because if the kernel + * boots with some cpus offline and then we online one of them + * the cpu notifier won't know which driver to assign + */ if (!drv->cpumask) drv->cpumask = (struct cpumask *)cpu_possible_mask;
+ /* + * we look for the timer stop flag in the different states, + * so know we have to setup the broadcast timer. The loop is + * in reverse order, because usually the deeper state has this + * flag set + */ for (i = drv->state_count - 1; i >= 0 ; i--) {
if (!(drv->states[i].flags & CPUIDLE_FLAG_TIMER_STOP)) @@ -111,6 +183,21 @@ static int __cpuidle_driver_init(struct cpuidle_driver *drv) return 0; }
+/** + * __cpuidle_register_driver: registers the driver + * @drv: a valid pointer to a struct cpuidle_driver + * + * Does some sanity checks, initializes the driver, assigns the driver + * to the global cpuidle driver variable(s) and setup the broadcast + * timer if the cpuidle driver has some states which shutdown the + * local timer. + * + * Returns 0 on success, a negative error otherwise: + * * -EINVAL if the driver pointer is NULL + * * -EINVAL if the not idle states available + * * -ENODEV if the cpuidle framework is disabled + * * -EBUSY if the driver is already assigned to the global variables + */ static int __cpuidle_register_driver(struct cpuidle_driver *drv) { int ret; @@ -137,8 +224,13 @@ 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 + * + * Checks the driver is no longer in use, resets 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 +248,13 @@ 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 + * + * Registers the driver by taking a lock to prevent multiple callers + * to [un]register a driver at the same time. + * + * Returns 0 on success, a negative error otherwise (refer to the + * __cpuidle_register_driver). */ int cpuidle_register_driver(struct cpuidle_driver *drv) { @@ -172,7 +270,11 @@ 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 a driver by taking a lock to prevent multiple callers + * to [un]register a driver at the same time. The specified driver + * must match the driver currently registered. */ void cpuidle_unregister_driver(struct cpuidle_driver *drv) { @@ -183,7 +285,9 @@ void cpuidle_unregister_driver(struct cpuidle_driver *drv) EXPORT_SYMBOL_GPL(cpuidle_unregister_driver);
/** - * cpuidle_get_driver - return the current driver + * cpuidle_get_driver - returns the driver tied with 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 +303,11 @@ 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 - returns the driver registered with 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 specified cpu */ struct cpuidle_driver *cpuidle_get_cpu_driver(struct cpuidle_device *dev) { @@ -210,6 +318,14 @@ struct cpuidle_driver *cpuidle_get_cpu_driver(struct cpuidle_device *dev) } EXPORT_SYMBOL_GPL(cpuidle_get_cpu_driver);
+/** + * cpuidle_driver_ref - gets a refcount for the driver + * + * This function takes a refcount for the driver assigned to the current cpu + * + * Returns a struct cpuidle_driver pointer, or NULL if no driver is registered + * for the current cpu + */ struct cpuidle_driver *cpuidle_driver_ref(void) { struct cpuidle_driver *drv; @@ -223,6 +339,12 @@ struct cpuidle_driver *cpuidle_driver_ref(void) return drv; }
+/** + * cpuidle_driver_unref - puts down the refcount for the driver + * + * This function decrements the refcount for the driver assigned to the current + * cpu. + */ void cpuidle_driver_unref(void) { struct cpuidle_driver *drv = cpuidle_get_driver();