2 * This file is part of the coreboot project.
4 * Copyright (C) 2005 Yinghai Lu <yinghailu@gmail.com>
6 * This program is free software; you can redistribute it and/or modify
7 * it under the terms of the GNU General Public License as published by
8 * the Free Software Foundation; either version 2 of the License, or
9 * (at your option) any later version.
11 * This program is distributed in the hope that it will be useful,
12 * but WITHOUT ANY WARRANTY; without even the implied warranty of
13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14 * GNU General Public License for more details.
16 * You should have received a copy of the GNU General Public License
17 * along with this program; if not, write to the Free Software
18 * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
21 #include <device/smbus_def.h>
23 void enable_smbus(void);
25 static void smbus_delay(void)
30 static int smbus_wait_until_ready(u16 smbus_io_base)
32 unsigned loops = SMBUS_TIMEOUT;
38 byte = inb(smbus_io_base + SMBHSTSTAT);
40 return loops ? 0 : -1;
43 static int smbus_wait_until_done(u16 smbus_io_base)
45 unsigned loops = SMBUS_TIMEOUT;
51 byte = inb(smbus_io_base + SMBHSTSTAT);
52 } while ((byte & 1) || (byte & ~((1 << 6) | (1 << 0))) == 0);
53 return loops ? 0 : -1;
56 static int do_smbus_read_byte(u16 smbus_io_base, u8 device, u8 address)
58 unsigned char global_status_register;
61 if (smbus_wait_until_ready(smbus_io_base) < 0) {
62 return SMBUS_WAIT_UNTIL_READY_TIMEOUT;
64 /* Setup transaction */
65 /* Disable interrupts */
66 outb(inb(smbus_io_base + SMBHSTCTL) & (~1), SMBUS_IO_BASE + SMBHSTCTL);
67 /* Set the device I'm talking too */
68 outb(((device & 0x7f) << 1) | 1, smbus_io_base + SMBXMITADD);
69 /* Set the command/address... */
70 outb(address & 0xff, smbus_io_base + SMBHSTCMD);
71 /* Set up for a byte data read */
72 outb((inb(smbus_io_base + SMBHSTCTL) & 0xe3) | (0x2 << 2),
73 (smbus_io_base + SMBHSTCTL));
74 /* Clear any lingering errors, so the transaction will run */
75 outb(inb(smbus_io_base + SMBHSTSTAT), SMBUS_IO_BASE + SMBHSTSTAT);
77 /* Clear the data byte... */
78 outb(0, smbus_io_base + SMBHSTDAT0);
80 /* Start the command */
81 outb((inb(smbus_io_base + SMBHSTCTL) | 0x40),
82 smbus_io_base + SMBHSTCTL);
84 /* Poll for transaction completion */
85 if (smbus_wait_until_done(smbus_io_base) < 0) {
86 return SMBUS_WAIT_UNTIL_DONE_TIMEOUT;
89 global_status_register = inb(smbus_io_base + SMBHSTSTAT);
91 /* Ignore the "In Use" status... */
92 global_status_register &= ~(3 << 5);
94 /* Read results of transaction */
95 byte = inb(smbus_io_base + SMBHSTDAT0);
96 if (global_status_register != (1 << 1)) {