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Commit a52879e8 authored by Thierry Reding's avatar Thierry Reding
Browse files

drm/dsi: Add message to packet translator 



This commit introduces a new function, mipi_dsi_create_packet(), which
converts from a MIPI DSI message to a MIPI DSI packet. The MIPI DSI
packet is as close to the protocol described in the DSI specification as
possible and useful in drivers that need to write a DSI packet into a
FIFO to send a message off to the peripheral.

Suggested-by: default avatarAndrzej Hajda <a.hajda@samsung.com>
Reviewed-by: default avatarSean Paul <seanpaul@chromium.org>
Signed-off-by: default avatarThierry Reding <treding@nvidia.com>
parent 02acb76d

drivers/gpu/drm/drm_mipi_dsi.c

+53 −0
Original line number Diff line number Diff line
@@ -265,6 +265,59 @@ bool mipi_dsi_packet_format_is_long(u8 type) 
}

EXPORT_SYMBOL(mipi_dsi_packet_format_is_long);



/**

 * mipi_dsi_create_packet - create a packet from a message according to the

 *     DSI protocol

 * @packet: pointer to a DSI packet structure

 * @msg: message to translate into a packet

 *

 * Return: 0 on success or a negative error code on failure.

 */

int mipi_dsi_create_packet(struct mipi_dsi_packet *packet,

			   const struct mipi_dsi_msg *msg)

{

	const u8 *tx = msg->tx_buf;



	if (!packet || !msg)

		return -EINVAL;



	/* do some minimum sanity checking */

	if (!mipi_dsi_packet_format_is_short(msg->type) &&

	    !mipi_dsi_packet_format_is_long(msg->type))

		return -EINVAL;



	if (msg->channel > 3)

		return -EINVAL;



	memset(packet, 0, sizeof(*packet));

	packet->header[0] = ((msg->channel & 0x3) << 6) | (msg->type & 0x3f);



	/* TODO: compute ECC if hardware support is not available */



	/*

	 * Long write packets contain the word count in header bytes 1 and 2.

	 * The payload follows the header and is word count bytes long.

	 *

	 * Short write packets encode up to two parameters in header bytes 1

	 * and 2.

	 */

	if (mipi_dsi_packet_format_is_long(msg->type)) {

		packet->header[1] = (msg->tx_len >> 0) & 0xff;

		packet->header[2] = (msg->tx_len >> 8) & 0xff;



		packet->payload_length = msg->tx_len;

		packet->payload = tx;

	} else {

		packet->header[1] = (msg->tx_len > 0) ? tx[0] : 0;

		packet->header[2] = (msg->tx_len > 1) ? tx[1] : 0;

	}



	packet->size = sizeof(packet->header) + packet->payload_length;



	return 0;

}

EXPORT_SYMBOL(mipi_dsi_create_packet);



/**

 * mipi_dsi_dcs_write - send DCS write command

 * @dsi: DSI device

include/drm/drm_mipi_dsi.h

+18 −0
Original line number Diff line number Diff line
@@ -46,6 +46,24 @@ struct mipi_dsi_msg { 
bool mipi_dsi_packet_format_is_short(u8 type);

bool mipi_dsi_packet_format_is_long(u8 type);



/**

 * struct mipi_dsi_packet - represents a MIPI DSI packet in protocol format

 * @size: size (in bytes) of the packet

 * @header: the four bytes that make up the header (Data ID, Word Count or

 *     Packet Data, and ECC)

 * @payload_length: number of bytes in the payload

 * @payload: a pointer to a buffer containing the payload, if any

 */

struct mipi_dsi_packet {

	size_t size;

	u8 header[4];

	size_t payload_length;

	const u8 *payload;

};



int mipi_dsi_create_packet(struct mipi_dsi_packet *packet,

			   const struct mipi_dsi_msg *msg);



/**

 * struct mipi_dsi_host_ops - DSI bus operations

 * @attach: attach DSI device to DSI host