greybus: camera-gb: Add description of interface header

/* Output flags returned */

#define GB_CAMERA_OUT_FLAG_ADJUSTED	(1 << 0)

/**

 * struct gb_camera_stream - Represents greybus camera stream.

 * @width: Stream width in pixels.

 * @height: Stream height in pixels.

 * @pixel_code: Media bus pixel code.

 * @vc: MIPI CSI virtual channel.

 * @dt: MIPI CSI data types. Most formats use a single data type, in which case

 *      the second element will be ignored.

 * @max_size: Maximum size of a frame in bytes. The camera module guarantees

 *            that all data between the Frame Start and Frame End packet for

 *            the associated virtual channel and data type(s) will not exceed

 *            this size.

 */

struct gb_camera_stream {

	unsigned int width;

	unsigned int height;

 * struct gb_camera_csi_params - CSI configuration parameters

 * @num_lanes: number of CSI data lanes

 * @clk_freq: CSI clock frequency in Hz

 * @lines_per_second:	total number of lines in a second of transmission

 * @lines_per_second: Total number of lines in a second of transmission

 *                    (blanking included)

 */

struct gb_camera_csi_params {

	unsigned int lines_per_second;

};

/**

 * struct gb_camera_ops - Greybus camera operations, used by the Greybus camera

 *                        driver to expose operations to the host camera driver.

 * @capabilities: Retrieve camera capabilities and store them in the buffer

 *                'buf' capabilities. The buffer maximum size is specified by

 *                the caller in the 'size' parameter, and the effective

 *                capabilities size is returned from the function. If the buffer

 *                size is too small to hold the capabilities an error is

 *                returned and the buffer is left untouched.

 *

 * @configure_streams: Negotiate configuration and prepare the module for video

 *                     capture. The caller specifies the number of streams it

 *                     requests in the 'nstreams' argument and the associated

 *                     streams configurations in the 'streams' argument. The

 *                     GB_CAMERA_IN_FLAG_TEST 'flag' can be set to test a

 *                     configuration without applying it, otherwise the

 *                     configuration is applied by the module. The module can

 *                     decide to modify the requested configuration, including

 *                     using a different number of streams. In that case the

 *                     modified configuration won't be applied, the

 *                     GB_CAMERA_OUT_FLAG_ADJUSTED 'flag' will be set upon

 *                     return, and the modified configuration and number of

 *                     streams stored in 'streams' and 'array'. The module

 *                     returns its CSI-2 bus parameters in the 'csi_params'

 *                     structure in all cases.

 *

 * @capture: Submit a capture request. The supplied 'request_id' must be unique

 *           and higher than the IDs of all the previously submitted requests.

 *           The 'streams' argument specifies which streams are affected by the

 *           request in the form of a bitmask, with bits corresponding to the

 *           configured streams indexes. If the request contains settings, the

 *           'settings' argument points to the settings buffer and its size is

 *           specified by the 'settings_size' argument. Otherwise the 'settings'

 *           argument should be set to NULL and 'settings_size' to 0.

 *

 * @flush: Flush the capture requests queue. Return the ID of the last request

 *         that will processed by the device before it stops transmitting video

 *         frames. All queued capture requests with IDs higher than the returned

 *         ID will be dropped without being processed.

 */

struct gb_camera_ops {

	ssize_t (*capabilities)(void *priv, char *buf, size_t len);

	int (*configure_streams)(void *priv, unsigned int *nstreams,

	int (*flush)(void *priv, u32 *request_id);

};

/**

 * struct gb_camera_module - Represents greybus camera module.

 * @priv: Module private data, passed to all camera operations.

 * @ops: Greybus camera operation callbacks.

 * @list: List entry in the camera modules list.

 */

struct gb_camera_module {

	void *priv;

	const struct gb_camera_ops *ops;