From: Thierry Reding treding@nvidia.com
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: Andrzej Hajda a.hajda@samsung.com Signed-off-by: Thierry Reding treding@nvidia.com --- drivers/gpu/drm/drm_mipi_dsi.c | 45 ++++++++++++++++++++++++++++++++++++++++++ include/drm/drm_mipi_dsi.h | 18 +++++++++++++++++ 2 files changed, 63 insertions(+)
diff --git a/drivers/gpu/drm/drm_mipi_dsi.c b/drivers/gpu/drm/drm_mipi_dsi.c index eb6dfe52cab2..76e81aba8220 100644 --- a/drivers/gpu/drm/drm_mipi_dsi.c +++ b/drivers/gpu/drm/drm_mipi_dsi.c @@ -199,6 +199,51 @@ int mipi_dsi_detach(struct mipi_dsi_device *dsi) EXPORT_SYMBOL(mipi_dsi_detach);
/** + * 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; + + 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 (msg->tx_len > 2) { + 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 * @data: pointer to the command followed by parameters diff --git a/include/drm/drm_mipi_dsi.h b/include/drm/drm_mipi_dsi.h index 8569dc5a1026..663aa68826f4 100644 --- a/include/drm/drm_mipi_dsi.h +++ b/include/drm/drm_mipi_dsi.h @@ -44,6 +44,24 @@ struct mipi_dsi_msg { };
/** + * 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 * @detach: detach DSI device from DSI host