diff options
Diffstat (limited to 'src/southbridge/intel/i82801dx/smbus.c')
-rw-r--r-- | src/southbridge/intel/i82801dx/smbus.c | 105 |
1 files changed, 105 insertions, 0 deletions
diff --git a/src/southbridge/intel/i82801dx/smbus.c b/src/southbridge/intel/i82801dx/smbus.c new file mode 100644 index 0000000000..1f7e47be95 --- /dev/null +++ b/src/southbridge/intel/i82801dx/smbus.c @@ -0,0 +1,105 @@ +/* + * This file is part of the coreboot project. + * + * Copyright (C) 2004 Ronald G. Minnich + * + * 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; version 2 of the License. + * + * 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. + * + * You should have received a copy of the GNU General Public License + * along with this program; if not, write to the Free Software + * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA + */ + +#include "i82801dx.h" +#include <smbus.h> +#include <pci.h> +#include <arch/io.h> + +#define PM_BUS 0 +#define PM_DEVFN PCI_DEVFN(0x1f,3) + +void smbus_enable(void) +{ + unsigned char byte; + /* iobase addr */ + pcibios_write_config_dword(PM_BUS, PM_DEVFN, 0x20, SMBUS_IO_BASE | 1); + /* smbus enable */ + pcibios_write_config_byte(PM_BUS, PM_DEVFN, 0x40, 1); + /* iospace enable */ + pcibios_write_config_word(PM_BUS, PM_DEVFN, 0x4, 1); + + /* Disable interrupt generation */ + outb(0, SMBUS_IO_BASE + SMBHSTCTL); + +} + +void smbus_setup(void) +{ + outb(0, SMBUS_IO_BASE + SMBHSTSTAT); +} + +static void smbus_wait_until_ready(void) +{ + while ((inb(SMBUS_IO_BASE + SMBHSTSTAT) & 1) == 1) { + /* nop */ + } +} + +static void smbus_wait_until_done(void) +{ + unsigned char byte; + do { + byte = inb(SMBUS_IO_BASE + SMBHSTSTAT); + } + while ((byte & 1) == 1); + while ((byte & ~1) == 0) { + byte = inb(SMBUS_IO_BASE + SMBHSTSTAT); + } +} + +int smbus_read_byte(unsigned device, unsigned address, unsigned char *result) +{ + unsigned char host_status_register; + unsigned char byte; + + smbus_wait_until_ready(); + + /* 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 + SMBHSTADD); + /* 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 */ + smbus_wait_until_done(); + + host_status_register = inb(SMBUS_IO_BASE + SMBHSTSTAT); + + /* read results of transaction */ + byte = inb(SMBUS_IO_BASE + SMBHSTDAT0); + + *result = byte; + return host_status_register != 0x02; +} |