| /* |
| * This file is part of the coreboot project. |
| * |
| * Copyright (C) 2005 Yinghai Lu <yinghailu@gmail.com> |
| * |
| * This program is free software; you can redistribute it and/or modify |
| * it under the terms of the GNU General Public License as published by |
| * the Free Software Foundation; either version 2 of the License, or |
| * (at your option) any later version. |
| * |
| * 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 <device/smbus_def.h> |
| |
| static void smbus_delay(void) |
| { |
| inb(0x80); |
| } |
| |
| static int smbus_wait_until_ready(u16 smbus_io_base) |
| { |
| unsigned loops = SMBUS_TIMEOUT; |
| unsigned char byte; |
| do { |
| smbus_delay(); |
| if (--loops == 0) |
| break; |
| byte = inb(smbus_io_base + SMBHSTSTAT); |
| } while (byte & 1); |
| return loops ? 0 : -1; |
| } |
| |
| static int smbus_wait_until_done(u16 smbus_io_base) |
| { |
| unsigned loops = SMBUS_TIMEOUT; |
| unsigned char byte; |
| do { |
| smbus_delay(); |
| if (--loops == 0) |
| break; |
| byte = inb(smbus_io_base + SMBHSTSTAT); |
| } while ((byte & 1) || (byte & ~((1 << 6) | (1 << 0))) == 0); |
| return loops ? 0 : -1; |
| } |
| |
| static int do_smbus_read_byte(u16 smbus_io_base, u8 device, u8 address) |
| { |
| unsigned char global_status_register; |
| unsigned char byte; |
| |
| if (smbus_wait_until_ready(smbus_io_base) < 0) { |
| return SMBUS_WAIT_UNTIL_READY_TIMEOUT; |
| } |
| /* Setup transaction */ |
| /* Disable interrupts */ |
| outb(inb(smbus_io_base + SMBHSTCTL) & (~1), SMBUS_IO_BASE + SMBHSTCTL); |
| /* Set the device I'm talking too */ |
| outb(((device & 0x7f) << 1) | 1, smbus_io_base + SMBXMITADD); |
| /* Set the command/address... */ |
| outb(address & 0xff, smbus_io_base + SMBHSTCMD); |
| /* Set up for a byte data read */ |
| outb((inb(smbus_io_base + SMBHSTCTL) & 0xe3) | (0x2 << 2), |
| (smbus_io_base + SMBHSTCTL)); |
| /* Clear any lingering errors, so the transaction will run */ |
| outb(inb(smbus_io_base + SMBHSTSTAT), SMBUS_IO_BASE + SMBHSTSTAT); |
| |
| /* Clear the data byte... */ |
| outb(0, smbus_io_base + SMBHSTDAT0); |
| |
| /* Start the command */ |
| outb((inb(smbus_io_base + SMBHSTCTL) | 0x40), |
| smbus_io_base + SMBHSTCTL); |
| |
| /* Poll for transaction completion */ |
| if (smbus_wait_until_done(smbus_io_base) < 0) { |
| return SMBUS_WAIT_UNTIL_DONE_TIMEOUT; |
| } |
| |
| global_status_register = inb(smbus_io_base + SMBHSTSTAT); |
| |
| /* Ignore the "In Use" status... */ |
| global_status_register &= ~(3 << 5); |
| |
| /* Read results of transaction */ |
| byte = inb(smbus_io_base + SMBHSTDAT0); |
| if (global_status_register != (1 << 1)) { |
| return SMBUS_ERROR; |
| } |
| return byte; |
| } |