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ef9424dd10
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
50 lines
1.2 KiB
C
50 lines
1.2 KiB
C
/* 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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#ifndef __MESSAGE_IF_H
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#define __MESSAGE_IF_H
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#include <common.h>
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/* Command interface between EC and AP */
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enum {
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MSG_TRAILER_BYTES = 1,
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MSG_PROTO_BYTES = MSG_TRAILER_BYTES,
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};
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/* The command codes that we understand */
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enum message_cmd_t {
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/* EC control/status messages */
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CMDC_PROTO_VER = 0x00, /* Protocol version */
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CMDC_NOP, /* No operation / ping */
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CMDC_ID, /* Read EC ID */
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/* Functional messages */
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CMDC_KEY_STATE = 0x20, /* Read key state */
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};
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/**
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* Process a command received and return the response
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*
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* There is no time to compute a reply. The data should be ready
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* immediately. This function can be called in interrupt context.
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*
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* The format of a reply is a sequence of bytes:
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*
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* <msg bytes> <sum>
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*
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* The checksum is calculated as the sum of all message bytes
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*
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* @param cmd Command to process (CMD_...)
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* @param buff Pointer to buffer to store reponse
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* @param max_len Maximum length of buffer
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* @return number of bytes in reply, 0 if none, -1 for unknown command
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*/
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int message_process_cmd(int cmd, uint8_t *buff, int max_len);
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#endif
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