ACPI/video: export acpi_video_get_levels

The acpi_video_get_levels is useful for other drivers, i.e. the
to-be-added int3406 thermal driver, so export it.

Signed-off-by: Aaron Lu <aaron.lu@intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
diff --git a/include/acpi/video.h b/include/acpi/video.h
index 5ca2f2c..a4b96c9 100644
--- a/include/acpi/video.h
+++ b/include/acpi/video.h
@@ -4,6 +4,19 @@
 #include <linux/errno.h> /* for ENODEV */
 #include <linux/types.h> /* for bool */
 
+struct acpi_video_brightness_flags {
+	u8 _BCL_no_ac_battery_levels:1;	/* no AC/Battery levels in _BCL */
+	u8 _BCL_reversed:1;		/* _BCL package is in a reversed order */
+	u8 _BQC_use_index:1;		/* _BQC returns an index value */
+};
+
+struct acpi_video_device_brightness {
+	int curr;
+	int count;
+	int *levels;
+	struct acpi_video_brightness_flags flags;
+};
+
 struct acpi_device;
 
 #define ACPI_VIDEO_CLASS	"video"
@@ -37,6 +50,8 @@
  * may change over time and should not be cached.
  */
 extern bool acpi_video_handles_brightness_key_presses(void);
+extern int acpi_video_get_levels(struct acpi_device *device,
+				 struct acpi_video_device_brightness **dev_br);
 #else
 static inline int acpi_video_register(void) { return 0; }
 static inline void acpi_video_unregister(void) { return; }
@@ -56,6 +71,11 @@
 {
 	return false;
 }
+static int acpi_video_get_levels(struct acpi_device *device,
+			struct acpi_video_device_brightness **dev_br)
+{
+	return -ENODEV;
+}
 #endif
 
 #endif