/* * This file is part of the coreboot project. * * Copyright (C) 2005 Yinghai Lu <yinghailu@gmail.com> * Copyright (C) 2009 coresystems GmbH * * 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. */ #include <device/smbus_def.h> #include "pch.h" static void smbus_delay(void) { inb(0x80); } static int smbus_wait_until_ready(u16 smbus_base) { unsigned loops = SMBUS_TIMEOUT; unsigned char byte; do { smbus_delay(); if (--loops == 0) break; byte = inb(smbus_base + SMBHSTSTAT); } while (byte & 1); return loops ? 0 : -1; } static int smbus_wait_until_done(u16 smbus_base) { unsigned loops = SMBUS_TIMEOUT; unsigned char byte; do { smbus_delay(); if (--loops == 0) break; byte = inb(smbus_base + SMBHSTSTAT); } while ((byte & 1) || (byte & ~((1 << 6) | (1 << 0))) == 0); return loops ? 0 : -1; } static int do_smbus_read_byte(unsigned smbus_base, unsigned device, unsigned address) { unsigned char global_status_register; unsigned char byte; if (smbus_wait_until_ready(smbus_base) < 0) { return SMBUS_WAIT_UNTIL_READY_TIMEOUT; } /* Setup transaction */ /* Disable interrupts */ outb(inb(smbus_base + SMBHSTCTL) & (~1), smbus_base + SMBHSTCTL); /* Set the device I'm talking too */ outb(((device & 0x7f) << 1) | 1, smbus_base + SMBXMITADD); /* Set the command/address... */ outb(address & 0xff, smbus_base + SMBHSTCMD); /* Set up for a byte data read */ outb((inb(smbus_base + SMBHSTCTL) & 0xe3) | (0x2 << 2), (smbus_base + SMBHSTCTL)); /* Clear any lingering errors, so the transaction will run */ outb(inb(smbus_base + SMBHSTSTAT), smbus_base + SMBHSTSTAT); /* Clear the data byte... */ outb(0, smbus_base + SMBHSTDAT0); /* Start the command */ outb((inb(smbus_base + SMBHSTCTL) | 0x40), smbus_base + SMBHSTCTL); /* Poll for transaction completion */ if (smbus_wait_until_done(smbus_base) < 0) { return SMBUS_WAIT_UNTIL_DONE_TIMEOUT; } global_status_register = inb(smbus_base + SMBHSTSTAT); /* Ignore the "In Use" status... */ global_status_register &= ~(3 << 5); /* Read results of transaction */ byte = inb(smbus_base + SMBHSTDAT0); if (global_status_register != (1 << 1)) { return SMBUS_ERROR; } return byte; }