1 files changed, 205 insertions, 119 deletions

diff --git a/drivers/cpuidle/driver.c b/drivers/cpuidle/driver.c
index 8dfaaae94444..3ac499d5a207 100644
--- a/drivers/cpuidle/driver.c
+++ b/drivers/cpuidle/driver.c
@@ -18,182 +18,249 @@
 
 DEFINE_SPINLOCK(cpuidle_driver_lock);
 
-static void __cpuidle_set_cpu_driver(struct cpuidle_driver *drv, int cpu);
-static struct cpuidle_driver * __cpuidle_get_cpu_driver(int cpu);
+#ifdef CONFIG_CPU_IDLE_MULTIPLE_DRIVERS
 
-static void cpuidle_setup_broadcast_timer(void *arg)
+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)
 {
-	int cpu = smp_processor_id();
-	clockevents_notify((long)(arg), &cpu);
+	return per_cpu(cpuidle_drivers, cpu);
 }
 
-static void __cpuidle_driver_init(struct cpuidle_driver *drv, int 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 i;
-
-	drv->refcnt = 0;
+	int cpu;
 
-	for (i = drv->state_count - 1; i >= 0 ; i--) {
+	for_each_cpu(cpu, drv->cpumask) {
 
-		if (!(drv->states[i].flags & CPUIDLE_FLAG_TIMER_STOP))
+		if (drv != __cpuidle_get_cpu_driver(cpu))
 			continue;
 
-		drv->bctimer = 1;
-		on_each_cpu_mask(get_cpu_mask(cpu), cpuidle_setup_broadcast_timer,
-				 (void *)CLOCK_EVT_NOTIFY_BROADCAST_ON, 1);
-		break;
+		per_cpu(cpuidle_drivers, cpu) = NULL;
 	}
 }
 
-static int __cpuidle_register_driver(struct cpuidle_driver *drv, int cpu)
+/**
+ * __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)
 {
-	if (!drv || !drv->state_count)
-		return -EINVAL;
-
-	if (cpuidle_disabled())
-		return -ENODEV;
+	int cpu;
 
-	if (__cpuidle_get_cpu_driver(cpu))
-		return -EBUSY;
+	for_each_cpu(cpu, drv->cpumask) {
 
-	__cpuidle_driver_init(drv, cpu);
+		if (__cpuidle_get_cpu_driver(cpu)) {
+			__cpuidle_unset_driver(drv);
+			return -EBUSY;
+		}
 
-	__cpuidle_set_cpu_driver(drv, cpu);
+		per_cpu(cpuidle_drivers, cpu) = drv;
+	}
 
 	return 0;
 }
 
-static void __cpuidle_unregister_driver(struct cpuidle_driver *drv, int cpu)
-{
-	if (drv != __cpuidle_get_cpu_driver(cpu))
-		return;
+#else
 
-	if (!WARN_ON(drv->refcnt > 0))
-		__cpuidle_set_cpu_driver(NULL, cpu);
+static struct cpuidle_driver *cpuidle_curr_driver;
 
-	if (drv->bctimer) {
-		drv->bctimer = 0;
-		on_each_cpu_mask(get_cpu_mask(cpu), cpuidle_setup_broadcast_timer,
-				 (void *)CLOCK_EVT_NOTIFY_BROADCAST_OFF, 1);
-	}
+/**
+ * __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;
 }
 
-#ifdef CONFIG_CPU_IDLE_MULTIPLE_DRIVERS
+/**
+ * __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;
 
-static DEFINE_PER_CPU(struct cpuidle_driver *, cpuidle_drivers);
+	cpuidle_curr_driver = drv;
 
-static void __cpuidle_set_cpu_driver(struct cpuidle_driver *drv, int cpu)
-{
-	per_cpu(cpuidle_drivers, cpu) = drv;
+	return 0;
 }
 
-static struct cpuidle_driver *__cpuidle_get_cpu_driver(int cpu)
+/**
+ * __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)
 {
-	return per_cpu(cpuidle_drivers, cpu);
+	if (drv == cpuidle_curr_driver)
+		cpuidle_curr_driver = NULL;
 }
 
-static void __cpuidle_unregister_all_cpu_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;
-	for_each_present_cpu(cpu)
-		__cpuidle_unregister_driver(drv, cpu);
+	int cpu = smp_processor_id();
+	clockevents_notify((long)(arg), &cpu);
 }
 
-static int __cpuidle_register_all_cpu_driver(struct cpuidle_driver *drv)
+/**
+ * __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 ret = 0;
-	int i, cpu;
+	int i;
 
-	for_each_present_cpu(cpu) {
-		ret = __cpuidle_register_driver(drv, cpu);
-		if (ret)
-			break;
-	}
+	drv->refcnt = 0;
 
-	if (ret)
-		for_each_present_cpu(i) {
-			if (i == cpu)
-				break;
-			__cpuidle_unregister_driver(drv, 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;
+
+	/*
+	 * 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))
+			continue;
 
-	return ret;
+		drv->bctimer = 1;
+		break;
+	}
+
+	return 0;
 }
 
-int cpuidle_register_cpu_driver(struct cpuidle_driver *drv, int cpu)
+/**
+ * __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;
 
-	spin_lock(&cpuidle_driver_lock);
-	ret = __cpuidle_register_driver(drv, cpu);
-	spin_unlock(&cpuidle_driver_lock);
+	if (!drv || !drv->state_count)
+		return -EINVAL;
 
-	return ret;
-}
+	if (cpuidle_disabled())
+		return -ENODEV;
 
-void cpuidle_unregister_cpu_driver(struct cpuidle_driver *drv, int cpu)
-{
-	spin_lock(&cpuidle_driver_lock);
-	__cpuidle_unregister_driver(drv, cpu);
-	spin_unlock(&cpuidle_driver_lock);
-}
+	ret = __cpuidle_driver_init(drv);
+	if (ret)
+		return ret;
 
-/**
- * cpuidle_register_driver - registers a driver
- * @drv: the driver
- */
-int cpuidle_register_driver(struct cpuidle_driver *drv)
-{
-	int ret;
+	ret = __cpuidle_set_driver(drv);
+	if (ret)
+		return ret;
 
-	spin_lock(&cpuidle_driver_lock);
-	ret = __cpuidle_register_all_cpu_driver(drv);
-	spin_unlock(&cpuidle_driver_lock);
+	if (drv->bctimer)
+		on_each_cpu_mask(drv->cpumask, cpuidle_setup_broadcast_timer,
+				 (void *)CLOCK_EVT_NOTIFY_BROADCAST_ON, 1);
 
-	return ret;
+	return 0;
 }
-EXPORT_SYMBOL_GPL(cpuidle_register_driver);
 
 /**
- * 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.
+ *
  */
-void cpuidle_unregister_driver(struct cpuidle_driver *drv)
+static void __cpuidle_unregister_driver(struct cpuidle_driver *drv)
 {
-	spin_lock(&cpuidle_driver_lock);
-	__cpuidle_unregister_all_cpu_driver(drv);
-	spin_unlock(&cpuidle_driver_lock);
-}
-EXPORT_SYMBOL_GPL(cpuidle_unregister_driver);
-
-#else
-
-static struct cpuidle_driver *cpuidle_curr_driver;
+	if (WARN_ON(drv->refcnt > 0))
+		return;
 
-static inline void __cpuidle_set_cpu_driver(struct cpuidle_driver *drv, int cpu)
-{
-	cpuidle_curr_driver = drv;
-}
+	if (drv->bctimer) {
+		drv->bctimer = 0;
+		on_each_cpu_mask(drv->cpumask, cpuidle_setup_broadcast_timer,
+				 (void *)CLOCK_EVT_NOTIFY_BROADCAST_OFF, 1);
+	}
 
-static inline struct cpuidle_driver *__cpuidle_get_cpu_driver(int cpu)
-{
-	return cpuidle_curr_driver;
+	__cpuidle_unset_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)
 {
-	int ret, cpu;
+	int ret;
 
-	cpu = get_cpu();
 	spin_lock(&cpuidle_driver_lock);
-	ret = __cpuidle_register_driver(drv, cpu);
+	ret = __cpuidle_register_driver(drv);
 	spin_unlock(&cpuidle_driver_lock);
-	put_cpu();
 
 	return ret;
 }
@@ -201,23 +268,24 @@ 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)
 {
-	int cpu;
-
-	cpu = get_cpu();
 	spin_lock(&cpuidle_driver_lock);
-	__cpuidle_unregister_driver(drv, cpu);
+	__cpuidle_unregister_driver(drv);
 	spin_unlock(&cpuidle_driver_lock);
-	put_cpu();
 }
 EXPORT_SYMBOL_GPL(cpuidle_unregister_driver);
-#endif
 
 /**
- * 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)
 {
@@ -233,7 +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)
 {
@@ -244,6 +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;
@@ -257,6 +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();