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/*
* This file is part of the coreboot project.
*
* Copyright (C) 2007 Advanced Micro Devices, Inc.
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*/
#include <console/console.h>
#include <arch/io.h>
#include "cs5536.h"
#include "smbus.h"
#define SMBUS_TIMEOUT (1000)
static void smbus_delay(void)
{
/* inb(0x80); */
}
static int smbus_wait(unsigned smbus_io_base)
{
unsigned long loops = SMBUS_TIMEOUT;
unsigned char val;
do {
smbus_delay();
val = inb(smbus_io_base + SMB_STS);
if ((val & SMB_STS_SDAST) != 0)
break;
if (val & (SMB_STS_BER | SMB_STS_NEGACK)) {
/*printk(BIOS_DEBUG, "SMBUS WAIT ERROR %x\n", val); */
return SMBUS_ERROR;
}
} while (--loops);
return loops ? 0 : SMBUS_WAIT_UNTIL_READY_TIMEOUT;
}
/* generate a smbus start condition */
int smbus_start_condition(unsigned smbus_io_base)
{
unsigned char val;
/* issue a START condition */
val = inb(smbus_io_base + SMB_CTRL1);
outb(val | SMB_CTRL1_START, smbus_io_base + SMB_CTRL1);
/* check for bus conflict */
val = inb(smbus_io_base + SMB_STS);
if ((val & SMB_STS_BER) != 0)
return SMBUS_ERROR;
return smbus_wait(smbus_io_base);
}
int smbus_check_stop_condition(unsigned smbus_io_base)
{
unsigned char val;
unsigned long loops;
loops = SMBUS_TIMEOUT;
/* check for SDA status */
do {
smbus_delay();
val = inb(smbus_io_base + SMB_CTRL1);
if ((val & SMB_CTRL1_STOP) == 0) {
break;
}
outb((0x7F << 1) | SMB_CTRL2_ENABLE, smbus_io_base + SMB_CTRL2);
} while (--loops);
return loops ? 0 : SMBUS_WAIT_UNTIL_READY_TIMEOUT;
}
int smbus_stop_condition(unsigned smbus_io_base)
{
outb(SMB_CTRL1_STOP, smbus_io_base + SMB_CTRL1);
return smbus_wait(smbus_io_base);
}
static int smbus_ack(unsigned smbus_io_base, int state)
{
unsigned char val = inb(smbus_io_base + SMB_CTRL1);
/* if (state) */
outb(val | SMB_CTRL1_ACK, smbus_io_base + SMB_CTRL1);
/* else
outb(val & ~SMB_CTRL1_ACK, smbus_io_base + SMB_CTRL1);
*/
return 0;
}
int smbus_send_slave_address(unsigned smbus_io_base,
unsigned char device)
{
unsigned char val;
/* send the slave address */
outb(device, smbus_io_base + SMB_SDA);
/* check for bus conflict and NACK */
val = inb(smbus_io_base + SMB_STS);
if (((val & SMB_STS_BER) != 0) || ((val & SMB_STS_NEGACK) != 0)) {
/* printk(BIOS_DEBUG, "SEND SLAVE ERROR (%x)\n", val); */
return SMBUS_ERROR;
}
return smbus_wait(smbus_io_base);
}
int smbus_send_command(unsigned smbus_io_base, unsigned char command)
{
unsigned char val;
/* send the command */
outb(command, smbus_io_base + SMB_SDA);
/* check for bus conflict and NACK */
val = inb(smbus_io_base + SMB_STS);
if (((val & SMB_STS_BER) != 0) || ((val & SMB_STS_NEGACK) != 0))
return SMBUS_ERROR;
return smbus_wait(smbus_io_base);
}
static unsigned char smbus_get_result(unsigned smbus_io_base)
{
return inb(smbus_io_base + SMB_SDA);
}
unsigned char do_smbus_read_byte(unsigned smbus_io_base,
unsigned char device,
unsigned char address)
{
unsigned char error = 0;
if ((smbus_check_stop_condition(smbus_io_base))) {
error = 1;
goto err;
}
if ((smbus_start_condition(smbus_io_base))) {
error = 2;
goto err;
}
if ((smbus_send_slave_address(smbus_io_base, device << 1))) {
error = 3;
goto err;
}
smbus_ack(smbus_io_base, 1);
if ((smbus_send_command(smbus_io_base, address))) {
error = 4;
goto err;
}
if ((smbus_start_condition(smbus_io_base))) {
error = 5;
goto err;
}
if ((smbus_send_slave_address(smbus_io_base, (device << 1) | 0x01))) {
error = 6;
goto err;
}
if ((smbus_stop_condition(smbus_io_base))) {
error = 7;
goto err;
}
return smbus_get_result(smbus_io_base);
err:
printk(BIOS_DEBUG, "SMBUS READ ERROR: %02x device: %02x\n", error, device);
/* stop, clean up the error, and leave */
smbus_stop_condition(smbus_io_base);
outb(inb(smbus_io_base + SMB_STS), smbus_io_base + SMB_STS);
outb(0x0, smbus_io_base + SMB_STS);
return 0xFF;
}
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