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Merge "simplified message protocol"

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Gerrit
2012-04-25 16:08:34 -07:00
committed by Gerrit Code Review
parent d85fa75275 ef9424dd10
commit 0d53a4cb66
2 changed files with 23 additions and 40 deletions
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32
common/message.c
View File

@@ -13,9 +13,12 @@
#include "keyboard_scan.h"
#include "util.h"
/* Our ID message - Matrix KeyBoard Protocol */
static const char proto_id[] = "Google Chrome MKBP v1";
/* EC ID */
/* (TODO(dhendrix): Define this in board-specific code */
static const char ec_id[] = "Google Chrome EC";
/* Protocol version (least significant byte in lowest byte position) */
static const uint8_t proto_ver[] = { 1, 0, 0, 0 };
/**
* Get the response to a given command
@@ -34,12 +37,15 @@ static int message_get_response(int cmd, uint8_t **buffp, int max_len)
* Invalid commands are ignored, just returning a stream of 0xff
* bytes.
*/
switch (cmd & MSG_CMD_MASK) {
switch (cmd) {
case CMDC_PROTO_VER:
*buffp = (uint8_t *)proto_ver;
return sizeof(proto_ver);
case CMDC_NOP:
return 0;
case CMDC_ID:
*buffp = (char *)proto_id;
return sizeof(proto_id) - 1;
*buffp = (char *)ec_id;
return sizeof(ec_id) - 1;
case CMDC_KEY_STATE:
return keyboard_get_scan(buffp, max_len);
default:
@@ -55,10 +61,9 @@ int message_process_cmd(int cmd, uint8_t *out_msg, int max_len)
int msg_len;
int need_copy;
int sum = 0;
int len;
int i;
msg = out_msg + MSG_HEADER_BYTES;
msg = out_msg;
msg_len = message_get_response(cmd, &msg, max_len - MSG_PROTO_BYTES);
if (msg_len < 0)
return msg_len;
@@ -69,25 +74,18 @@ int message_process_cmd(int cmd, uint8_t *out_msg, int max_len)
*/
if (msg_len + MSG_PROTO_BYTES > max_len)
msg_len = max_len - MSG_PROTO_BYTES;
len = msg_len + MSG_PROTO_BYTES;
ASSERT(msg_len >= 0 && msg_len < 0xffff);
need_copy = msg != out_msg + MSG_HEADER_BYTES;
need_copy = msg != out_msg;
ASSERT(!need_copy ||
msg + msg_len < out_msg ||
msg > out_msg + sizeof(out_msg));
out_msg[0] = MSG_HEADER;
out_msg[1] = len & 0xff;
out_msg[2] = (len >> 8) & 0xff;
sum += MSG_HEADER + len + (len >> 8);
for (i = 0; i < msg_len; i++) {
if (need_copy)
out_msg[i + 3] = msg[i];
out_msg[i] = msg[i];
sum += msg[i];
}
out_msg[i + 3] = sum & 0xff;
out_msg[i + 4] = MSG_PREAMBLE;
out_msg[i] = sum;
return msg_len + MSG_PROTO_BYTES;
}

31
include/message.h
View File

@@ -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>
* <msg bytes> <sum>
*
* 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.
*
* 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