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drm/dsi: Add message to packet translator

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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>
Reviewed-by: Sean Paul <seanpaul@chromium.org>
Signed-off-by: Thierry Reding <treding@nvidia.com>
This commit is contained in:
Thierry Reding 2014-10-16 13:44:02 +02:00
parent 02acb76d72
commit a52879e8d7
2 changed files with 71 additions and 0 deletions
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53
drivers/gpu/drm/drm_mipi_dsi.c
View File

@ -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

18
include/drm/drm_mipi_dsi.h
View File

@ -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