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Whatever means is used to talk to the AP there is no justifcation for putting message processing directly in drivers. Create a suitable header file to define the interface, and provide a processing function which can provide responses to incoming messages. BUG=chromium-os:28925 TEST=build on daisy and discovery; run on daisy Change-Id: If09ea3e30d42d8c5f226dc4421d4895adc54f937 Signed-off-by: Simon Glass <sjg@chromium.org>
62 lines
1.7 KiB
C
62 lines
1.7 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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/* Mask to convert a command byte into a command */
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MSG_CMD_MASK = 0x7f,
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/* The bytes which appear before the header in a message */
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MSG_PREAMBLE = 0xff,
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/* The header byte, which follows the preamble */
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MSG_HEADER = 0xec,
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MSG_HEADER_BYTES = 3,
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MSG_TRAILER_BYTES = 2,
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MSG_PROTO_BYTES = MSG_HEADER_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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CMDC_NOP, /* No operation / ping */
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CMDC_ID, /* Read EC ID */
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CMDC_KEY_STATE, /* 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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* <hdr> <len_lo> <len_hi> <msg bytes> <sum> <preamble bytes>
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*
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* The hdr byte is just a tag to indicate that the real message follows. It
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* signals the end of any preamble required by the interface.
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*
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* The 16-bit length includes the length of the header, len bytes, message
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* and checksum, but not the final preamble byte.
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*
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* The checksum is calculated as the sum of the header, len byte and message.
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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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