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| author | David Hendricks <dhendrix@chromium.org> | 2012-04-25 11:40:11 -0700 |
|---|---|---|
| committer | David Hendricks <dhendrix@chromium.org> | 2012-04-25 14:51:33 -0700 |
| commit | ef9424dd1058d1f49692ecf10d7b1b207b175e15 (patch) | |
| tree | d8f4db5a65adb85ec36ae03ad1b67f49d2344bcb /include | |
| parent | 83082746a9a463ad6a964cfc2f2abd0bf08d95fb (diff) | |
| download | chrome-ec-ef9424dd1058d1f49692ecf10d7b1b207b175e15.tar.gz | |
simplified message protocol
This simplifies the messaging protocol. Messages will now only have
the raw content plus a checksum byte at the end. We will worry about
needs of the transport layer (e.g. preamble/postamble bytes) on the
host driver side, and will not support variable-length commands for
now.
There is also a protocol version command, which is now command number
0x00, which returns a 4-byte protocol version followed by a 1-byte
checksum.
BUG=none
TEST=tested on daisy using mkbp kernel driver
Signed-off-by: David Hendricks <dhendrix@chromium.org>
Change-Id: I8fcc693cd50bc2b515164ea7a2a941cdd8333e73
Diffstat (limited to 'include')
| -rw-r--r-- | include/message.h | 31 |
1 files changed, 8 insertions, 23 deletions
diff --git a/include/message.h b/include/message.h index 0930eb24f1..439c6df67e 100644 --- a/include/message.h +++ b/include/message.h @@ -11,28 +11,19 @@ /* Command interface between EC and AP */ enum { - /* Mask to convert a command byte into a command */ - MSG_CMD_MASK = 0x7f, - - /* The bytes which appear before the header in a message */ - MSG_PREAMBLE = 0xff, - - /* The header byte, which follows the preamble */ - MSG_HEADER = 0xec, - - MSG_HEADER_BYTES = 3, - MSG_TRAILER_BYTES = 2, - MSG_PROTO_BYTES = MSG_HEADER_BYTES + MSG_TRAILER_BYTES, + MSG_TRAILER_BYTES = 1, + MSG_PROTO_BYTES = MSG_TRAILER_BYTES, }; /* The command codes that we understand */ enum message_cmd_t { - /* control / status messages */ + /* EC control/status messages */ + CMDC_PROTO_VER = 0x00, /* Protocol version */ CMDC_NOP, /* No operation / ping */ CMDC_ID, /* Read EC ID */ - /* functional messages */ - CMDC_KEY_STATE = 0x20, /* Read key state */ + /* Functional messages */ + CMDC_KEY_STATE = 0x20, /* Read key state */ }; @@ -44,15 +35,9 @@ enum message_cmd_t { * * The format of a reply is a sequence of bytes: * - * <hdr> <len_lo> <len_hi> <msg bytes> <sum> <preamble bytes> - * - * The hdr byte is just a tag to indicate that the real message follows. It - * signals the end of any preamble required by the interface. - * - * The 16-bit length is the entire packet size, including the header, length - * bytes, message payload, checksum, and postamble byte. + * <msg bytes> <sum> * - * The checksum is calculated as the sum of the header, len byte and message. + * The checksum is calculated as the sum of all message bytes * * @param cmd Command to process (CMD_...) * @param buff Pointer to buffer to store reponse |