media: Add bus type to frame descriptors

Add the media bus type to the frame descriptor. CSI-2 specific
information will be added in next patch to the frame descriptor.

- Make the bus type a named enum
Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Reviewed-by: Niklas Söderlund <niklas.soderlund+renesas@ragnatech.se>
Signed-off-by: Jacopo Mondi <jacopo+renesas@jmondi.org>
Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ideasonboard.com>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@kernel.org>

include/media/v4l2-subdev.h

@@ -344,12 +344,32 @@ struct v4l2_mbus_frame_desc_entry {
 
 #define V4L2_FRAME_DESC_ENTRY_MAX	4
 
+/**
+ * enum v4l2_mbus_frame_desc_type - media bus frame description type
+ *
+ * @V4L2_MBUS_FRAME_DESC_TYPE_UNDEFINED:
+ *	Undefined frame desc type. Drivers should not use this, it is
+ *	for backwards compatibility.
+ * @V4L2_MBUS_FRAME_DESC_TYPE_PARALLEL:
+ *	Parallel media bus.
+ * @V4L2_MBUS_FRAME_DESC_TYPE_CSI2:
+ *	CSI-2 media bus. Frame desc parameters must be set in
+ *	&struct v4l2_mbus_frame_desc_entry->csi2.
+ */
+enum v4l2_mbus_frame_desc_type {
+	V4L2_MBUS_FRAME_DESC_TYPE_UNDEFINED = 0,
+	V4L2_MBUS_FRAME_DESC_TYPE_PARALLEL,
+	V4L2_MBUS_FRAME_DESC_TYPE_CSI2,
+};
+
 /**
  * struct v4l2_mbus_frame_desc - media bus data frame description
+ * @type: type of the bus (enum v4l2_mbus_frame_desc_type)
  * @entry: frame descriptors array
  * @num_entries: number of entries in @entry array
  */
 struct v4l2_mbus_frame_desc {
+	enum v4l2_mbus_frame_desc_type type;
 	struct v4l2_mbus_frame_desc_entry entry[V4L2_FRAME_DESC_ENTRY_MAX];
 	unsigned short num_entries;
 };