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path: root/src/southbridge/intel/i3100/smbus.c
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/*
 * This file is part of the coreboot project.
 *
 * Copyright (C) 2008 Arastra, 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.
 *
 * 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 <device/device.h>
#include <device/path.h>
#include <device/pci.h>
#include <device/pci_ids.h>
#include <device/pci_ops.h>
#include <device/smbus.h>
#include <arch/io.h>
#include "i3100.h"
#include "smbus.h"

#ifndef __PRE_RAM__
static int lsmbus_read_byte(device_t dev, u8 address)
{
	u16 device;
	struct resource *res;
	struct bus *pbus;

	device = dev->path.i2c.device;
	pbus = get_pbus_smbus(dev);
	res = find_resource(pbus->dev, 0x20);

	return do_smbus_read_byte(res->base, device, address);
}

static struct smbus_bus_operations lops_smbus_bus = {
	.read_byte  = lsmbus_read_byte,
};

static void smbus_set_subsystem(device_t dev, unsigned vendor, unsigned device)
{
	pci_write_config32(dev, PCI_SUBSYSTEM_VENDOR_ID,
		((device & 0xffff) << 16) | (vendor & 0xffff));
}

static struct pci_operations lops_pci = {
	.set_subsystem = &smbus_set_subsystem,
};

static struct device_operations smbus_ops = {
	.read_resources   = pci_dev_read_resources,
	.set_resources    = pci_dev_set_resources,
	.enable_resources = pci_dev_enable_resources,
	.init             = 0,
	.scan_bus         = scan_static_bus,
	.enable           = i3100_enable,
	.ops_pci          = &lops_pci,
	.ops_smbus_bus    = &lops_smbus_bus,
};

static const struct pci_driver smbus_driver __pci_driver = {
	.ops    = &smbus_ops,
	.vendor = PCI_VENDOR_ID_INTEL,
	.device = PCI_DEVICE_ID_INTEL_3100_SMB,
};

static const struct pci_driver smbus_driver_ep80579 __pci_driver = {
	.ops    = &smbus_ops,
	.vendor = PCI_VENDOR_ID_INTEL,
	.device = PCI_DEVICE_ID_INTEL_EP80579_SMB,
};
#endif /* __PRE_RAM__ */

void smbus_delay(void)
{
	outb(0x80, 0x80);
}

int smbus_wait_until_ready(u32 smbus_io_base)
{
	u32 loops = SMBUS_TIMEOUT;
	u8 byte;
	do {
		smbus_delay();
		if (--loops == 0)
			break;
		byte = inb(smbus_io_base + SMBHSTSTAT);
	} while (byte & 1);
	return loops ? 0 : -1;
}

int smbus_wait_until_done(u32 smbus_io_base)
{
	u32 loops = SMBUS_TIMEOUT;
	u8 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;
}

int do_smbus_read_byte(u32 smbus_io_base, u16 device, u8 address)
{
	u8 global_status_register;
	u8 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) | SMBUS_READ, 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;
}