ACPI: Introduce new device wakeup flag 'prepared'

Introduce additional flag 'prepared' in struct acpi_device_wakeup_flags
and use it to prevent devices from being enable/disabled do wake up the
system multiple times in a row (this does not happen currently, but will
be possible after some of the following patches).
Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>

drivers/acpi/power.c

@@ -363,11 +363,18 @@ int acpi_device_sleep_wake(struct acpi_device *dev,
  */
 int acpi_enable_wakeup_device_power(struct acpi_device *dev, int sleep_state)
 {
-	int i;
+	int i, err;
 
 	if (!dev || !dev->wakeup.flags.valid)
 		return -EINVAL;
 
+	/*
+	 * Do not execute the code below twice in a row without calling
+	 * acpi_disable_wakeup_device_power() in between for the same device
+	 */
+	if (dev->wakeup.flags.prepared)
+		return 0;
+
 	/* Open power resource */
 	for (i = 0; i < dev->wakeup.resources.count; i++) {
 		int ret = acpi_power_on(dev->wakeup.resources.handles[i], dev);
@@ -382,7 +389,11 @@ int acpi_enable_wakeup_device_power(struct acpi_device *dev, int sleep_state)
 	 * Passing 3 as the third argument below means the device may be placed
 	 * in arbitrary power state afterwards.
 	 */
-	return acpi_device_sleep_wake(dev, 1, sleep_state, 3);
+	err = acpi_device_sleep_wake(dev, 1, sleep_state, 3);
+	if (!err)
+		dev->wakeup.flags.prepared = 1;
+
+	return err;
 }
 
 /*
@@ -398,6 +409,15 @@ int acpi_disable_wakeup_device_power(struct acpi_device *dev)
 	if (!dev || !dev->wakeup.flags.valid)
 		return -EINVAL;
 
+	/*
+	 * Do not execute the code below twice in a row without calling
+	 * acpi_enable_wakeup_device_power() in between for the same device
+	 */
+	if (!dev->wakeup.flags.prepared)
+		return 0;
+
+	dev->wakeup.flags.prepared = 0;
+
 	ret = acpi_device_sleep_wake(dev, 0, 0, 0);
 	if (ret)
 		return ret;

include/acpi/acpi_bus.h

@@ -259,6 +259,7 @@ struct acpi_device_perf {
 /* Wakeup Management */
 struct acpi_device_wakeup_flags {
 	u8 valid:1;		/* Can successfully enable wakeup? */
+	u8 prepared:1;		/* Has the wake-up capability been enabled? */
 	u8 run_wake:1;		/* Run-Wake GPE devices */
 };