ACPI / PM: Introduce function for refcounting device power resources

Introduce function acpi_power_on_resources() that reference counts
and possibly turns on ACPI power resources for a given device and
a given power state of it.

This function will be used for reference counting device power
resources during initialization.
Signed-off-by: NRafael J. Wysocki <rjw@sisk.pl>
Signed-off-by: NLen Brown <len.brown@intel.com>

drivers/acpi/internal.h

@@ -42,6 +42,7 @@ int acpi_power_init(void);
 int acpi_device_sleep_wake(struct acpi_device *dev,
                            int enable, int sleep_state, int dev_state);
 int acpi_power_get_inferred_state(struct acpi_device *device, int *state);
+int acpi_power_on_resources(struct acpi_device *device, int state);
 int acpi_power_transition(struct acpi_device *device, int state);
 extern int acpi_power_nocheck;
 

drivers/acpi/power.c

@@ -485,6 +485,14 @@ int acpi_power_get_inferred_state(struct acpi_device *device, int *state)
 	return 0;
 }
 
+int acpi_power_on_resources(struct acpi_device *device, int state)
+{
+	if (!device || state < ACPI_STATE_D0 || state > ACPI_STATE_D3)
+		return -EINVAL;
+
+	return acpi_power_on_list(&device->power.states[state].resources);
+}
+
 int acpi_power_transition(struct acpi_device *device, int state)
 {
 	int result;