[media] V4L: Add [get/set]_frame_desc subdev callbacks

Add subdev callbacks for setting up parameters of the frame on media bus
that are not exposed to user space directly. This is just an initial,
mostly stub implementation. struct v4l2_mbus_frame_desc is intended
to be extended with sub-structures specific to a particular hardware media
bus. For now these new callbacks are used only to query or specify maximum
size of a compressed or hybrid (container) media bus frame in octets.

Signed-off-by: Sylwester Nawrocki <s.nawrocki@samsung.com>
Signed-off-by: Kyungmin Park <kyungmin.park@samsung.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>

include/media/v4l2-subdev.h

@@ -21,6 +21,7 @@
 #ifndef _V4L2_SUBDEV_H
 #define _V4L2_SUBDEV_H
 
+#include <linux/types.h>
 #include <linux/v4l2-subdev.h>
 #include <media/media-entity.h>
 #include <media/v4l2-common.h>
@@ -45,6 +46,7 @@ struct v4l2_fh;
 struct v4l2_subdev;
 struct v4l2_subdev_fh;
 struct tuner_setup;
+struct v4l2_mbus_frame_desc;
 
 /* decode_vbi_line */
 struct v4l2_decode_vbi_line {
@@ -226,6 +228,36 @@ struct v4l2_subdev_audio_ops {
 	int (*s_stream)(struct v4l2_subdev *sd, int enable);
 };
 
+/* Indicates the @length field specifies maximum data length. */
+#define V4L2_MBUS_FRAME_DESC_FL_LEN_MAX		(1U << 0)
+/* Indicates user defined data format, i.e. non standard frame format. */
+#define V4L2_MBUS_FRAME_DESC_FL_BLOB		(1U << 1)
+
+/**
+ * struct v4l2_mbus_frame_desc_entry - media bus frame description structure
+ * @flags: V4L2_MBUS_FRAME_DESC_FL_* flags
+ * @pixelcode: media bus pixel code, valid if FRAME_DESC_FL_BLOB is not set
+ * @length: number of octets per frame, valid for compressed or unspecified
+ *          formats
+ */
+struct v4l2_mbus_frame_desc_entry {
+	u16 flags;
+	u32 pixelcode;
+	u32 length;
+};
+
+#define V4L2_FRAME_DESC_ENTRY_MAX	4
+
+/**
+ * struct v4l2_mbus_frame_desc - media bus data frame description
+ * @entry: frame descriptors array
+ * @num_entries: number of entries in @entry array
+ */
+struct v4l2_mbus_frame_desc {
+	struct v4l2_mbus_frame_desc_entry entry[V4L2_FRAME_DESC_ENTRY_MAX];
+	unsigned short num_entries;
+};
+
 /*
    s_std_output: set v4l2_std_id for video OUTPUT devices. This is ignored by
 	video input devices.
@@ -461,6 +493,12 @@ struct v4l2_subdev_ir_ops {
 				struct v4l2_subdev_ir_parameters *params);
 };
 
+/**
+ * struct v4l2_subdev_pad_ops - v4l2-subdev pad level operations
+ * @get_frame_desc: get the current low level media bus frame parameters.
+ * @get_frame_desc: set the low level media bus frame parameters, @fd array
+ *                  may be adjusted by the subdev driver to device capabilities.
+ */
 struct v4l2_subdev_pad_ops {
 	int (*enum_mbus_code)(struct v4l2_subdev *sd, struct v4l2_subdev_fh *fh,
 			      struct v4l2_subdev_mbus_code_enum *code);
@@ -489,6 +527,10 @@ struct v4l2_subdev_pad_ops {
 			     struct v4l2_subdev_format *source_fmt,
 			     struct v4l2_subdev_format *sink_fmt);
 #endif /* CONFIG_MEDIA_CONTROLLER */
+	int (*get_frame_desc)(struct v4l2_subdev *sd, unsigned int pad,
+			      struct v4l2_mbus_frame_desc *fd);
+	int (*set_frame_desc)(struct v4l2_subdev *sd, unsigned int pad,
+			      struct v4l2_mbus_frame_desc *fd);
 };
 
 struct v4l2_subdev_ops {