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/* Copyright (c) 2014 The Chromium OS Authors. All rights reserved.
* Use of this source code is governed by a BSD-style license that can be
* found in the LICENSE file.
*
* smbus cross-platform code for Chrome EC
* ref: http://smbus.org/specs/smbus20.pdf
*/
#include "common.h"
#include "console.h"
#include "util.h"
#include "i2c.h"
#include "smbus.h"
#include "crc8.h"
#define CPRINTF(format, args...) cprintf(CC_I2C, format, ## args)
/* Write 2 bytes using smbus word access protocol */
int smbus_write_word(uint8_t i2c_port, uint8_t slave_addr,
uint8_t smbus_cmd, uint16_t d16)
{
uint8_t buf[5];
/* Command sequence for CRC calculation */
buf[0] = slave_addr;
buf[1] = smbus_cmd;
buf[2] = d16 & 0xff;
buf[3] = (d16 >> 8) & 0xff;
buf[4] = crc8(buf, 4);
return i2c_xfer(i2c_port, slave_addr, buf + 1, 4, NULL, 0);
}
/* Write up to SMBUS_MAX_BLOCK_SIZE bytes using smbus block access protocol */
int smbus_write_block(uint8_t i2c_port, uint8_t slave_addr,
uint8_t smbus_cmd, uint8_t *data, uint8_t len)
{
uint8_t buf[3];
int rv;
/* Command sequence for CRC calculation */
buf[0] = slave_addr;
buf[1] = smbus_cmd;
buf[2] = len;
i2c_lock(i2c_port, 1);
/* Send command + length */
rv = i2c_xfer_unlocked(i2c_port, slave_addr,
buf + 1, 2, NULL, 0, I2C_XFER_START);
if (rv != EC_SUCCESS)
goto smbus_write_block_done;
/* Send data */
rv = i2c_xfer_unlocked(i2c_port, slave_addr, data, len, NULL, 0, 0);
if (rv != EC_SUCCESS)
goto smbus_write_block_done;
/* Send CRC */
buf[0] = crc8(buf, 3);
buf[0] = crc8_arg(data, len, buf[0]);
rv = i2c_xfer_unlocked(i2c_port, slave_addr, buf, 1, NULL, 0,
I2C_XFER_STOP);
smbus_write_block_done:
i2c_lock(i2c_port, 0);
return rv;
}
/* Read 2 bytes using smbus word access protocol */
int smbus_read_word(uint8_t i2c_port, uint8_t slave_addr,
uint8_t smbus_cmd, uint16_t *p16)
{
uint8_t buf[3];
int rv;
uint8_t crc;
/* Command sequence for CRC calculation */
buf[0] = slave_addr;
buf[1] = smbus_cmd;
buf[2] = slave_addr | 0x1;
crc = crc8(buf, 3);
/* Read data bytes + CRC byte */
rv = i2c_xfer(i2c_port, slave_addr, &smbus_cmd, 1, buf, 3);
/* Verify CRC */
if (crc8_arg(buf, 2, crc) != buf[2])
rv = EC_ERROR_CRC;
if (rv == EC_SUCCESS)
*p16 = (buf[1] << 8) | buf[0];
else
*p16 = 0;
return rv;
}
/* Read up to SMBUS_MAX_BLOCK_SIZE bytes using smbus block access protocol */
int smbus_read_block(uint8_t i2c_port, uint8_t slave_addr,
uint8_t smbus_cmd, uint8_t *data, uint8_t *plen)
{
int rv, read_len;
uint8_t buf[4];
uint8_t crc;
int do_crc = 1;
/* Command sequence for CRC calculation */
buf[0] = slave_addr;
buf[1] = smbus_cmd;
buf[2] = slave_addr | 0x1;
i2c_lock(i2c_port, 1);
/* First read size from slave */
rv = i2c_xfer_unlocked(i2c_port, slave_addr,
&smbus_cmd, 1, buf + 3, 1, I2C_XFER_START);
if (rv != EC_SUCCESS)
goto smbus_read_block_done;
crc = crc8(buf, 4);
/*
* If our input buffer isn't large enough to hold the entire input,
* don't bother verifying crc since it may require reading numerous
* data bytes that will be thrown away.
*/
read_len = MIN(buf[3], SMBUS_MAX_BLOCK_SIZE);
if (*plen < read_len) {
do_crc = 0;
read_len = *plen;
}
/* Now read back all bytes */
rv = i2c_xfer_unlocked(i2c_port, slave_addr,
NULL, 0, data, read_len, 0);
if (rv)
goto smbus_read_block_done;
/* Read CRC + verify */
rv = i2c_xfer_unlocked(i2c_port, slave_addr,
NULL, 0, buf, 1, I2C_XFER_STOP);
if (do_crc && crc8_arg(data, read_len, crc) != buf[0])
rv = EC_ERROR_CRC;
smbus_read_block_done:
if (rv != EC_SUCCESS)
memset(data, 0x0, *plen);
else
*plen = read_len;
i2c_lock(i2c_port, 0);
return rv;
}
int smbus_read_string(int i2c_port, uint8_t slave_addr, uint8_t smbus_cmd,
uint8_t *data, uint8_t len)
{
int rv;
len -= 1;
rv = smbus_read_block(i2c_port, slave_addr, smbus_cmd, data, &len);
data[len] = '\0';
return rv;
}
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