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https://github.com/Telecominfraproject/OpenCellular.git
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e56ba2e689
This simply changes the constant '4' to MSG_PROTO_BYTES, which includes the postamble. This helps reduce magic constant values used in processing a packet. BUG=chrome-os-partner:8975 TEST=tested on daisy (with kernel mkbp driver change) Signed-off-by: David Hendricks <dhendrix@chromium.org> Change-Id: Id4634076ad63f45783354179dfebea4fd450fc1e
94 lines
2.2 KiB
C
94 lines
2.2 KiB
C
/*
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* This handles incoming commands and provides responses.
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*
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* Copyright (c) 2012 The Chromium OS Authors. All rights reserved.
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* Use of this source code is governed by a BSD-style license that can be
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* found in the LICENSE file.
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*
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* EC <--> AP message handling.
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*/
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#include "board.h"
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#include "message.h"
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#include "keyboard_scan.h"
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#include "util.h"
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/* Our ID message - Matrix KeyBoard Protocol */
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static const char proto_id[] = "Google Chrome MKBP v1";
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/**
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* Get the response to a given command
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*
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* @param cmd Command byte to respond to
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* @param buffp Buffer to use for data, or it can be updated to
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* point to a new buffer
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* @param max_len Number of bytes free at *buffp for the response.
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* If the supplied buffer is used, this size must not
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* be exceeded.
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* @return number of bytes in response (which is in *buffp), or -1 on error
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*/
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static int message_get_response(int cmd, uint8_t **buffp, int max_len)
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{
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/*
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* Invalid commands are ignored, just returning a stream of 0xff
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* bytes.
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*/
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switch (cmd & MSG_CMD_MASK) {
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case CMDC_NOP:
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return 0;
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case CMDC_ID:
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*buffp = (char *)proto_id;
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return sizeof(proto_id) - 1;
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case CMDC_KEY_STATE:
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return keyboard_get_scan(buffp, max_len);
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default:
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return -1;
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}
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return 0;
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}
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int message_process_cmd(int cmd, uint8_t *out_msg, int max_len)
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{
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uint8_t *msg;
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int msg_len;
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int need_copy;
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int sum = 0;
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int len;
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int i;
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msg = out_msg + MSG_HEADER_BYTES;
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msg_len = message_get_response(cmd, &msg, max_len - MSG_PROTO_BYTES);
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if (msg_len < 0)
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return msg_len;
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/*
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* We add MSG_PROTO_BYTES bytes of overhead: truncate the reply
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* if needed.
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*/
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if (msg_len + MSG_PROTO_BYTES > max_len)
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msg_len = max_len - MSG_PROTO_BYTES;
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len = msg_len + MSG_PROTO_BYTES;
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ASSERT(msg_len >= 0 && msg_len < 0xffff);
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need_copy = msg != out_msg + MSG_HEADER_BYTES;
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ASSERT(!need_copy ||
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msg + msg_len < out_msg ||
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msg > out_msg + sizeof(out_msg));
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out_msg[0] = MSG_HEADER;
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out_msg[1] = len & 0xff;
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out_msg[2] = (len >> 8) & 0xff;
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sum += MSG_HEADER + len + (len >> 8);
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for (i = 0; i < msg_len; i++) {
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if (need_copy)
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out_msg[i + 3] = msg[i];
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sum += msg[i];
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}
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out_msg[i + 3] = sum & 0xff;
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out_msg[i + 4] = MSG_PREAMBLE;
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return msg_len + MSG_PROTO_BYTES;
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}
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