/* * 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; }