drivers/i2c/busses/i2c-viapro.c - linux - Git at Google

 /*
     i2c-viapro.c - Part of lm_sensors, Linux kernel modules for hardware
               monitoring
     Copyright (c) 1998 - 2002  Frodo Looijaard <frodol@dds.nl>,
     Philip Edelbrock <phil@netroedge.com>, Kyösti Mälkki <kmalkki@cc.hut.fi>,
     Mark D. Studebaker <mdsxyz123@yahoo.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.

     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., 675 Mass Ave, Cambridge, MA 02139, USA.
 */

 /*
    Supports Via devices:
 	82C596A/B (0x3050)
 	82C596B (0x3051)
 	82C686A/B
 	8231
 	8233
 	8233A (0x3147 and 0x3177)
 	8235
 	8237
    Note: we assume there can only be one device, with one SMBus interface.
 */

 #include <linux/module.h>
 #include <linux/delay.h>
 #include <linux/pci.h>
 #include <linux/kernel.h>
 #include <linux/stddef.h>
 #include <linux/sched.h>
 #include <linux/ioport.h>
 #include <linux/i2c.h>
 #include <linux/init.h>
 #include <asm/io.h>

 static struct pci_dev *vt596_pdev;

 #define SMBBA1	   	 0x90
 #define SMBBA2     	 0x80
 #define SMBBA3     	 0xD0

 /* SMBus address offsets */
 static unsigned short vt596_smba;
 #define SMBHSTSTS	(vt596_smba + 0)
 #define SMBHSLVSTS	(vt596_smba + 1)
 #define SMBHSTCNT	(vt596_smba + 2)
 #define SMBHSTCMD	(vt596_smba + 3)
 #define SMBHSTADD	(vt596_smba + 4)
 #define SMBHSTDAT0	(vt596_smba + 5)
 #define SMBHSTDAT1	(vt596_smba + 6)
 #define SMBBLKDAT	(vt596_smba + 7)
 #define SMBSLVCNT	(vt596_smba + 8)
 #define SMBSHDWCMD	(vt596_smba + 9)
 #define SMBSLVEVT	(vt596_smba + 0xA)
 #define SMBSLVDAT	(vt596_smba + 0xC)

 /* PCI Address Constants */

 /* SMBus data in configuration space can be found in two places,
    We try to select the better one*/

 static unsigned short smb_cf_hstcfg = 0xD2;

 #define SMBHSTCFG   (smb_cf_hstcfg)
 #define SMBSLVC     (smb_cf_hstcfg + 1)
 #define SMBSHDW1    (smb_cf_hstcfg + 2)
 #define SMBSHDW2    (smb_cf_hstcfg + 3)
 #define SMBREV      (smb_cf_hstcfg + 4)

 /* Other settings */
 #define MAX_TIMEOUT	500
 #define ENABLE_INT9	0

 /* VT82C596 constants */
 #define VT596_QUICK      0x00
 #define VT596_BYTE       0x04
 #define VT596_BYTE_DATA  0x08
 #define VT596_WORD_DATA  0x0C
 #define VT596_BLOCK_DATA 0x14


 /* If force is set to anything different from 0, we forcibly enable the
    VT596. DANGEROUS! */
 static int force;
 module_param(force, bool, 0);
 MODULE_PARM_DESC(force, "Forcibly enable the SMBus. DANGEROUS!");

 /* If force_addr is set to anything different from 0, we forcibly enable
    the VT596 at the given address. VERY DANGEROUS! */
 static u16 force_addr;
 module_param(force_addr, ushort, 0);
 MODULE_PARM_DESC(force_addr,
 		 "Forcibly enable the SMBus at the given address. "
 		 "EXTREMELY DANGEROUS!");


 static struct i2c_adapter vt596_adapter;

 /* Another internally used function */
 static int vt596_transaction(void)
 {
 	int temp;
 	int result = 0;
 	int timeout = 0;

 	dev_dbg(&vt596_adapter.dev, "Transaction (pre): CNT=%02x, CMD=%02x, "
 		"ADD=%02x, DAT0=%02x, DAT1=%02x\n", inb_p(SMBHSTCNT),
 		inb_p(SMBHSTCMD), inb_p(SMBHSTADD), inb_p(SMBHSTDAT0),
 		inb_p(SMBHSTDAT1));

 	/* Make sure the SMBus host is ready to start transmitting */
 	if ((temp = inb_p(SMBHSTSTS)) & 0x1F) {
 		dev_dbg(&vt596_adapter.dev, "SMBus busy (0x%02x). "
 				"Resetting...\n", temp);

 		outb_p(temp, SMBHSTSTS);
 		if ((temp = inb_p(SMBHSTSTS)) & 0x1F) {
 			dev_dbg(&vt596_adapter.dev, "Failed! (0x%02x)\n", temp);

 			return -1;
 		} else {
 			dev_dbg(&vt596_adapter.dev, "Successfull!\n");
 		}
 	}

 	/* start the transaction by setting bit 6 */
 	outb_p(inb(SMBHSTCNT) | 0x040, SMBHSTCNT);

 	/* We will always wait for a fraction of a second!
 	   I don't know if VIA needs this, Intel did  */
 	do {
 		msleep(1);
 		temp = inb_p(SMBHSTSTS);
 	} while ((temp & 0x01) && (timeout++ < MAX_TIMEOUT));

 	/* If the SMBus is still busy, we give up */
 	if (timeout >= MAX_TIMEOUT) {
 		result = -1;
 		dev_dbg(&vt596_adapter.dev, "SMBus Timeout!\n");
 	}

 	if (temp & 0x10) {
 		result = -1;
 		dev_dbg(&vt596_adapter.dev, "Error: Failed bus transaction\n");
 	}

 	if (temp & 0x08) {
 		result = -1;
 		dev_info(&vt596_adapter.dev, "Bus collision! SMBus may be "
 			"locked until next hard\nreset. (sorry!)\n");
 		/* Clock stops and slave is stuck in mid-transmission */
 	}

 	if (temp & 0x04) {
 		result = -1;
 		dev_dbg(&vt596_adapter.dev, "Error: no response!\n");
 	}

 	if ((temp = inb_p(SMBHSTSTS)) & 0x1F) {
 		outb_p(temp, SMBHSTSTS);
 		if ((temp = inb_p(SMBHSTSTS)) & 0x1F) {
 			dev_warn(&vt596_adapter.dev, "Failed reset at end "
 				 "of transaction (%02x)\n", temp);
 		}
 	}

 	dev_dbg(&vt596_adapter.dev, "Transaction (post): CNT=%02x, CMD=%02x, "
 		"ADD=%02x, DAT0=%02x, DAT1=%02x\n", inb_p(SMBHSTCNT),
 		inb_p(SMBHSTCMD), inb_p(SMBHSTADD), inb_p(SMBHSTDAT0),
 		inb_p(SMBHSTDAT1));

 	return result;
 }

 /* Return -1 on error. */
 static s32 vt596_access(struct i2c_adapter *adap, u16 addr,
 		unsigned short flags,  char read_write, u8 command,
 		int size,  union i2c_smbus_data *data)
 {
 	int i, len;

 	switch (size) {
 	case I2C_SMBUS_PROC_CALL:
 		dev_info(&vt596_adapter.dev,
 			 "I2C_SMBUS_PROC_CALL not supported!\n");
 		return -1;
 	case I2C_SMBUS_QUICK:
 		outb_p(((addr & 0x7f) << 1) | (read_write & 0x01),
 		       SMBHSTADD);
 		size = VT596_QUICK;
 		break;
 	case I2C_SMBUS_BYTE:
 		outb_p(((addr & 0x7f) << 1) | (read_write & 0x01),
 		       SMBHSTADD);
 		if (read_write == I2C_SMBUS_WRITE)
 			outb_p(command, SMBHSTCMD);
 		size = VT596_BYTE;
 		break;
 	case I2C_SMBUS_BYTE_DATA:
 		outb_p(((addr & 0x7f) << 1) | (read_write & 0x01),
 		       SMBHSTADD);
 		outb_p(command, SMBHSTCMD);
 		if (read_write == I2C_SMBUS_WRITE)
 			outb_p(data->byte, SMBHSTDAT0);
 		size = VT596_BYTE_DATA;
 		break;
 	case I2C_SMBUS_WORD_DATA:
 		outb_p(((addr & 0x7f) << 1) | (read_write & 0x01),
 		       SMBHSTADD);
 		outb_p(command, SMBHSTCMD);
 		if (read_write == I2C_SMBUS_WRITE) {
 			outb_p(data->word & 0xff, SMBHSTDAT0);
 			outb_p((data->word & 0xff00) >> 8, SMBHSTDAT1);
 		}
 		size = VT596_WORD_DATA;
 		break;
 	case I2C_SMBUS_BLOCK_DATA:
 		outb_p(((addr & 0x7f) << 1) | (read_write & 0x01),
 		       SMBHSTADD);
 		outb_p(command, SMBHSTCMD);
 		if (read_write == I2C_SMBUS_WRITE) {
 			len = data->block[0];
 			if (len < 0)
 				len = 0;
 			if (len > I2C_SMBUS_BLOCK_MAX)
 				len = I2C_SMBUS_BLOCK_MAX;
 			outb_p(len, SMBHSTDAT0);
 			i = inb_p(SMBHSTCNT);	/* Reset SMBBLKDAT */
 			for (i = 1; i <= len; i++)
 				outb_p(data->block[i], SMBBLKDAT);
 		}
 		size = VT596_BLOCK_DATA;
 		break;
 	}

 	outb_p((size & 0x1C) + (ENABLE_INT9 & 1), SMBHSTCNT);

 	if (vt596_transaction()) /* Error in transaction */
 		return -1;

 	if ((read_write == I2C_SMBUS_WRITE) || (size == VT596_QUICK))
 		return 0;

 	switch (size) {
 	case VT596_BYTE:
 		/* Where is the result put? I assume here it is in
 		 * SMBHSTDAT0 but it might just as well be in the
 		 * SMBHSTCMD. No clue in the docs
 		 */
 		data->byte = inb_p(SMBHSTDAT0);
 		break;
 	case VT596_BYTE_DATA:
 		data->byte = inb_p(SMBHSTDAT0);
 		break;
 	case VT596_WORD_DATA:
 		data->word = inb_p(SMBHSTDAT0) + (inb_p(SMBHSTDAT1) << 8);
 		break;
 	case VT596_BLOCK_DATA:
 		data->block[0] = inb_p(SMBHSTDAT0);
 		if (data->block[0] > I2C_SMBUS_BLOCK_MAX)
 			data->block[0] = I2C_SMBUS_BLOCK_MAX;
 		i = inb_p(SMBHSTCNT);	/* Reset SMBBLKDAT */
 		for (i = 1; i <= data->block[0]; i++)
 			data->block[i] = inb_p(SMBBLKDAT);
 		break;
 	}
 	return 0;
 }

 static u32 vt596_func(struct i2c_adapter *adapter)
 {
 	return I2C_FUNC_SMBUS_QUICK | I2C_FUNC_SMBUS_BYTE |
 	    I2C_FUNC_SMBUS_BYTE_DATA | I2C_FUNC_SMBUS_WORD_DATA |
 	    I2C_FUNC_SMBUS_BLOCK_DATA;
 }

 static struct i2c_algorithm smbus_algorithm = {
 	.smbus_xfer	= vt596_access,
 	.functionality	= vt596_func,
 };

 static struct i2c_adapter vt596_adapter = {
 	.owner		= THIS_MODULE,
 	.class		= I2C_CLASS_HWMON,
 	.algo		= &smbus_algorithm,
 	.name		= "unset",
 };

 static int __devinit vt596_probe(struct pci_dev *pdev,
 				 const struct pci_device_id *id)
 {
 	unsigned char temp;
 	int error = -ENODEV;

 	/* Determine the address of the SMBus areas */
 	if (force_addr) {
 		vt596_smba = force_addr & 0xfff0;
 		force = 0;
 		goto found;
 	}

 	if ((pci_read_config_word(pdev, id->driver_data, &vt596_smba)) ||
 	    !(vt596_smba & 0x1)) {
 		/* try 2nd address and config reg. for 596 */
 		if (id->device == PCI_DEVICE_ID_VIA_82C596_3 &&
 		    !pci_read_config_word(pdev, SMBBA2, &vt596_smba) &&
 		    (vt596_smba & 0x1)) {
 			smb_cf_hstcfg = 0x84;
 		} else {
 			/* no matches at all */
 			dev_err(&pdev->dev, "Cannot configure "
 				"SMBus I/O Base address\n");
 			return -ENODEV;
 		}
 	}

 	vt596_smba &= 0xfff0;
 	if (vt596_smba == 0) {
 		dev_err(&pdev->dev, "SMBus base address "
 			"uninitialized - upgrade BIOS or use "
 			"force_addr=0xaddr\n");
 		return -ENODEV;
 	}

  found:
 	if (!request_region(vt596_smba, 8, "viapro-smbus")) {
 		dev_err(&pdev->dev, "SMBus region 0x%x already in use!\n",
 		        vt596_smba);
 		return -ENODEV;
 	}

 	pci_read_config_byte(pdev, SMBHSTCFG, &temp);
 	/* If force_addr is set, we program the new address here. Just to make
 	   sure, we disable the VT596 first. */
 	if (force_addr) {
 		pci_write_config_byte(pdev, SMBHSTCFG, temp & 0xfe);
 		pci_write_config_word(pdev, id->driver_data, vt596_smba);
 		pci_write_config_byte(pdev, SMBHSTCFG, temp | 0x01);
 		dev_warn(&pdev->dev, "WARNING: SMBus interface set to new "
 		     "address 0x%04x!\n", vt596_smba);
 	} else if ((temp & 1) == 0) {
 		if (force) {
 			/* NOTE: This assumes I/O space and other allocations
 			 * WERE done by the Bios!  Don't complain if your
 			 * hardware does weird things after enabling this.
 			 * :') Check for Bios updates before resorting to
 			 * this.
 			 */
 			pci_write_config_byte(pdev, SMBHSTCFG, temp | 1);
 			dev_info(&pdev->dev, "Enabling SMBus device\n");
 		} else {
 			dev_err(&pdev->dev, "SMBUS: Error: Host SMBus "
 				"controller not enabled! - upgrade BIOS or "
 				"use force=1\n");
 			goto release_region;
 		}
 	}

 	if ((temp & 0x0E) == 8)
 		dev_dbg(&pdev->dev, "using Interrupt 9 for SMBus.\n");
 	else if ((temp & 0x0E) == 0)
 		dev_dbg(&pdev->dev, "using Interrupt SMI# for SMBus.\n");
 	else
 		dev_dbg(&pdev->dev, "Illegal Interrupt configuration "
 			"(or code out of date)!\n");

 	pci_read_config_byte(pdev, SMBREV, &temp);
 	dev_dbg(&pdev->dev, "SMBREV = 0x%X\n", temp);
 	dev_dbg(&pdev->dev, "VT596_smba = 0x%X\n", vt596_smba);

 	vt596_adapter.dev.parent = &pdev->dev;
 	snprintf(vt596_adapter.name, I2C_NAME_SIZE,
 			"SMBus Via Pro adapter at %04x", vt596_smba);

 	vt596_pdev = pci_dev_get(pdev);
 	if (i2c_add_adapter(&vt596_adapter)) {
 		pci_dev_put(vt596_pdev);
 		vt596_pdev = NULL;
 	}

 	/* Always return failure here.  This is to allow other drivers to bind
 	 * to this pci device.  We don't really want to have control over the
 	 * pci device, we only wanted to read as few register values from it.
 	 */
 	return -ENODEV;

  release_region:
 	release_region(vt596_smba, 8);
 	return error;
 }

 static struct pci_device_id vt596_ids[] = {
 	{ PCI_DEVICE(PCI_VENDOR_ID_VIA, PCI_DEVICE_ID_VIA_82C596_3),
 	  .driver_data = SMBBA1 },
 	{ PCI_DEVICE(PCI_VENDOR_ID_VIA, PCI_DEVICE_ID_VIA_82C596B_3),
 	  .driver_data = SMBBA1 },
 	{ PCI_DEVICE(PCI_VENDOR_ID_VIA, PCI_DEVICE_ID_VIA_82C686_4),
 	  .driver_data = SMBBA1 },
 	{ PCI_DEVICE(PCI_VENDOR_ID_VIA, PCI_DEVICE_ID_VIA_8233_0),
 	  .driver_data = SMBBA3 },
 	{ PCI_DEVICE(PCI_VENDOR_ID_VIA, PCI_DEVICE_ID_VIA_8233A),
 	  .driver_data = SMBBA3 },
 	{ PCI_DEVICE(PCI_VENDOR_ID_VIA, PCI_DEVICE_ID_VIA_8235),
 	  .driver_data = SMBBA3 },
 	{ PCI_DEVICE(PCI_VENDOR_ID_VIA, PCI_DEVICE_ID_VIA_8237),
 	  .driver_data = SMBBA3 },
 	{ PCI_DEVICE(PCI_VENDOR_ID_VIA, PCI_DEVICE_ID_VIA_8231_4),
 	  .driver_data = SMBBA1 },
 	{ 0, }
 };

 MODULE_DEVICE_TABLE (pci, vt596_ids);

 static struct pci_driver vt596_driver = {
 	.name		= "vt596_smbus",
 	.id_table	= vt596_ids,
 	.probe		= vt596_probe,
 };

 static int __init i2c_vt596_init(void)
 {
 	return pci_register_driver(&vt596_driver);
 }


 static void __exit i2c_vt596_exit(void)
 {
 	pci_unregister_driver(&vt596_driver);
 	if (vt596_pdev != NULL) {
 		i2c_del_adapter(&vt596_adapter);
 		release_region(vt596_smba, 8);
 		pci_dev_put(vt596_pdev);
 		vt596_pdev = NULL;
 	}
 }

 MODULE_AUTHOR(
     "Frodo Looijaard <frodol@dds.nl> and "
     "Philip Edelbrock <phil@netroedge.com>");
 MODULE_DESCRIPTION("vt82c596 SMBus driver");
 MODULE_LICENSE("GPL");

 module_init(i2c_vt596_init);
 module_exit(i2c_vt596_exit);
	/*
	i2c-viapro.c - Part of lm_sensors, Linux kernel modules for hardware
	monitoring
	Copyright (c) 1998 - 2002 Frodo Looijaard <frodol@dds.nl>,
	Philip Edelbrock <phil@netroedge.com>, Kyösti Mälkki <kmalkki@cc.hut.fi>,
	Mark D. Studebaker <mdsxyz123@yahoo.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.

	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., 675 Mass Ave, Cambridge, MA 02139, USA.
	*/

	/*
	Supports Via devices:
	82C596A/B (0x3050)
	82C596B (0x3051)
	82C686A/B
	8231
	8233
	8233A (0x3147 and 0x3177)
	8235
	8237
	Note: we assume there can only be one device, with one SMBus interface.
	*/

	#include <linux/module.h>
	#include <linux/delay.h>
	#include <linux/pci.h>
	#include <linux/kernel.h>
	#include <linux/stddef.h>
	#include <linux/sched.h>
	#include <linux/ioport.h>
	#include <linux/i2c.h>
	#include <linux/init.h>
	#include <asm/io.h>

	static struct pci_dev *vt596_pdev;

	#define SMBBA1 0x90
	#define SMBBA2 0x80
	#define SMBBA3 0xD0

	/* SMBus address offsets */
	static unsigned short vt596_smba;
	#define SMBHSTSTS (vt596_smba + 0)
	#define SMBHSLVSTS (vt596_smba + 1)
	#define SMBHSTCNT (vt596_smba + 2)
	#define SMBHSTCMD (vt596_smba + 3)
	#define SMBHSTADD (vt596_smba + 4)
	#define SMBHSTDAT0 (vt596_smba + 5)
	#define SMBHSTDAT1 (vt596_smba + 6)
	#define SMBBLKDAT (vt596_smba + 7)
	#define SMBSLVCNT (vt596_smba + 8)
	#define SMBSHDWCMD (vt596_smba + 9)
	#define SMBSLVEVT (vt596_smba + 0xA)
	#define SMBSLVDAT (vt596_smba + 0xC)

	/* PCI Address Constants */

	/* SMBus data in configuration space can be found in two places,
	We try to select the better one*/

	static unsigned short smb_cf_hstcfg = 0xD2;

	#define SMBHSTCFG (smb_cf_hstcfg)
	#define SMBSLVC (smb_cf_hstcfg + 1)
	#define SMBSHDW1 (smb_cf_hstcfg + 2)
	#define SMBSHDW2 (smb_cf_hstcfg + 3)
	#define SMBREV (smb_cf_hstcfg + 4)

	/* Other settings */
	#define MAX_TIMEOUT 500
	#define ENABLE_INT9 0

	/* VT82C596 constants */
	#define VT596_QUICK 0x00
	#define VT596_BYTE 0x04
	#define VT596_BYTE_DATA 0x08
	#define VT596_WORD_DATA 0x0C
	#define VT596_BLOCK_DATA 0x14


	/* If force is set to anything different from 0, we forcibly enable the
	VT596. DANGEROUS! */
	static int force;
	module_param(force, bool, 0);
	MODULE_PARM_DESC(force, "Forcibly enable the SMBus. DANGEROUS!");

	/* If force_addr is set to anything different from 0, we forcibly enable
	the VT596 at the given address. VERY DANGEROUS! */
	static u16 force_addr;
	module_param(force_addr, ushort, 0);
	MODULE_PARM_DESC(force_addr,
	"Forcibly enable the SMBus at the given address. "
	"EXTREMELY DANGEROUS!");


	static struct i2c_adapter vt596_adapter;

	/* Another internally used function */
	static int vt596_transaction(void)
	{
	int temp;
	int result = 0;
	int timeout = 0;

	dev_dbg(&vt596_adapter.dev, "Transaction (pre): CNT=%02x, CMD=%02x, "
	"ADD=%02x, DAT0=%02x, DAT1=%02x\n", inb_p(SMBHSTCNT),
	inb_p(SMBHSTCMD), inb_p(SMBHSTADD), inb_p(SMBHSTDAT0),
	inb_p(SMBHSTDAT1));

	/* Make sure the SMBus host is ready to start transmitting */
	if ((temp = inb_p(SMBHSTSTS)) & 0x1F) {
	dev_dbg(&vt596_adapter.dev, "SMBus busy (0x%02x). "
	"Resetting...\n", temp);

	outb_p(temp, SMBHSTSTS);
	if ((temp = inb_p(SMBHSTSTS)) & 0x1F) {
	dev_dbg(&vt596_adapter.dev, "Failed! (0x%02x)\n", temp);

	return -1;
	} else {
	dev_dbg(&vt596_adapter.dev, "Successfull!\n");
	}
	}

	/* start the transaction by setting bit 6 */
	outb_p(inb(SMBHSTCNT) \| 0x040, SMBHSTCNT);

	/* We will always wait for a fraction of a second!
	I don't know if VIA needs this, Intel did */
	do {
	msleep(1);
	temp = inb_p(SMBHSTSTS);
	} while ((temp & 0x01) && (timeout++ < MAX_TIMEOUT));

	/* If the SMBus is still busy, we give up */
	if (timeout >= MAX_TIMEOUT) {
	result = -1;
	dev_dbg(&vt596_adapter.dev, "SMBus Timeout!\n");
	}

	if (temp & 0x10) {
	result = -1;
	dev_dbg(&vt596_adapter.dev, "Error: Failed bus transaction\n");
	}

	if (temp & 0x08) {
	result = -1;
	dev_info(&vt596_adapter.dev, "Bus collision! SMBus may be "
	"locked until next hard\nreset. (sorry!)\n");
	/* Clock stops and slave is stuck in mid-transmission */
	}

	if (temp & 0x04) {
	result = -1;
	dev_dbg(&vt596_adapter.dev, "Error: no response!\n");
	}

	if ((temp = inb_p(SMBHSTSTS)) & 0x1F) {
	outb_p(temp, SMBHSTSTS);
	if ((temp = inb_p(SMBHSTSTS)) & 0x1F) {
	dev_warn(&vt596_adapter.dev, "Failed reset at end "
	"of transaction (%02x)\n", temp);
	}
	}

	dev_dbg(&vt596_adapter.dev, "Transaction (post): CNT=%02x, CMD=%02x, "
	"ADD=%02x, DAT0=%02x, DAT1=%02x\n", inb_p(SMBHSTCNT),
	inb_p(SMBHSTCMD), inb_p(SMBHSTADD), inb_p(SMBHSTDAT0),
	inb_p(SMBHSTDAT1));

	return result;
	}

	/* Return -1 on error. */
	static s32 vt596_access(struct i2c_adapter *adap, u16 addr,
	unsigned short flags, char read_write, u8 command,
	int size, union i2c_smbus_data *data)
	{
	int i, len;

	switch (size) {
	case I2C_SMBUS_PROC_CALL:
	dev_info(&vt596_adapter.dev,
	"I2C_SMBUS_PROC_CALL not supported!\n");
	return -1;
	case I2C_SMBUS_QUICK:
	outb_p(((addr & 0x7f) << 1) \| (read_write & 0x01),
	SMBHSTADD);
	size = VT596_QUICK;
	break;
	case I2C_SMBUS_BYTE:
	outb_p(((addr & 0x7f) << 1) \| (read_write & 0x01),
	SMBHSTADD);
	if (read_write == I2C_SMBUS_WRITE)
	outb_p(command, SMBHSTCMD);
	size = VT596_BYTE;
	break;
	case I2C_SMBUS_BYTE_DATA:
	outb_p(((addr & 0x7f) << 1) \| (read_write & 0x01),
	SMBHSTADD);
	outb_p(command, SMBHSTCMD);
	if (read_write == I2C_SMBUS_WRITE)
	outb_p(data->byte, SMBHSTDAT0);
	size = VT596_BYTE_DATA;
	break;
	case I2C_SMBUS_WORD_DATA:
	outb_p(((addr & 0x7f) << 1) \| (read_write & 0x01),
	SMBHSTADD);
	outb_p(command, SMBHSTCMD);
	if (read_write == I2C_SMBUS_WRITE) {
	outb_p(data->word & 0xff, SMBHSTDAT0);
	outb_p((data->word & 0xff00) >> 8, SMBHSTDAT1);
	}
	size = VT596_WORD_DATA;
	break;
	case I2C_SMBUS_BLOCK_DATA:
	outb_p(((addr & 0x7f) << 1) \| (read_write & 0x01),
	SMBHSTADD);
	outb_p(command, SMBHSTCMD);
	if (read_write == I2C_SMBUS_WRITE) {
	len = data->block[0];
	if (len < 0)
	len = 0;
	if (len > I2C_SMBUS_BLOCK_MAX)
	len = I2C_SMBUS_BLOCK_MAX;
	outb_p(len, SMBHSTDAT0);
	i = inb_p(SMBHSTCNT); /* Reset SMBBLKDAT */
	for (i = 1; i <= len; i++)
	outb_p(data->block[i], SMBBLKDAT);
	}
	size = VT596_BLOCK_DATA;
	break;
	}

	outb_p((size & 0x1C) + (ENABLE_INT9 & 1), SMBHSTCNT);

	if (vt596_transaction()) /* Error in transaction */
	return -1;

	if ((read_write == I2C_SMBUS_WRITE) \|\| (size == VT596_QUICK))
	return 0;

	switch (size) {
	case VT596_BYTE:
	/* Where is the result put? I assume here it is in
	* SMBHSTDAT0 but it might just as well be in the
	* SMBHSTCMD. No clue in the docs
	*/
	data->byte = inb_p(SMBHSTDAT0);
	break;
	case VT596_BYTE_DATA:
	data->byte = inb_p(SMBHSTDAT0);
	break;
	case VT596_WORD_DATA:
	data->word = inb_p(SMBHSTDAT0) + (inb_p(SMBHSTDAT1) << 8);
	break;
	case VT596_BLOCK_DATA:
	data->block[0] = inb_p(SMBHSTDAT0);
	if (data->block[0] > I2C_SMBUS_BLOCK_MAX)
	data->block[0] = I2C_SMBUS_BLOCK_MAX;
	i = inb_p(SMBHSTCNT); /* Reset SMBBLKDAT */
	for (i = 1; i <= data->block[0]; i++)
	data->block[i] = inb_p(SMBBLKDAT);
	break;
	}
	return 0;
	}

	static u32 vt596_func(struct i2c_adapter *adapter)
	{
	return I2C_FUNC_SMBUS_QUICK \| I2C_FUNC_SMBUS_BYTE \|
	I2C_FUNC_SMBUS_BYTE_DATA \| I2C_FUNC_SMBUS_WORD_DATA \|
	I2C_FUNC_SMBUS_BLOCK_DATA;
	}

	static struct i2c_algorithm smbus_algorithm = {
	.smbus_xfer = vt596_access,
	.functionality = vt596_func,
	};

	static struct i2c_adapter vt596_adapter = {
	.owner = THIS_MODULE,
	.class = I2C_CLASS_HWMON,
	.algo = &smbus_algorithm,
	.name = "unset",
	};

	static int __devinit vt596_probe(struct pci_dev *pdev,
	const struct pci_device_id *id)
	{
	unsigned char temp;
	int error = -ENODEV;

	/* Determine the address of the SMBus areas */
	if (force_addr) {
	vt596_smba = force_addr & 0xfff0;
	force = 0;
	goto found;
	}

	if ((pci_read_config_word(pdev, id->driver_data, &vt596_smba)) \|\|
	!(vt596_smba & 0x1)) {
	/* try 2nd address and config reg. for 596 */
	if (id->device == PCI_DEVICE_ID_VIA_82C596_3 &&
	!pci_read_config_word(pdev, SMBBA2, &vt596_smba) &&
	(vt596_smba & 0x1)) {
	smb_cf_hstcfg = 0x84;
	} else {
	/* no matches at all */
	dev_err(&pdev->dev, "Cannot configure "
	"SMBus I/O Base address\n");
	return -ENODEV;
	}
	}

	vt596_smba &= 0xfff0;
	if (vt596_smba == 0) {
	dev_err(&pdev->dev, "SMBus base address "
	"uninitialized - upgrade BIOS or use "
	"force_addr=0xaddr\n");
	return -ENODEV;
	}

	found:
	if (!request_region(vt596_smba, 8, "viapro-smbus")) {
	dev_err(&pdev->dev, "SMBus region 0x%x already in use!\n",
	vt596_smba);
	return -ENODEV;
	}

	pci_read_config_byte(pdev, SMBHSTCFG, &temp);
	/* If force_addr is set, we program the new address here. Just to make
	sure, we disable the VT596 first. */
	if (force_addr) {
	pci_write_config_byte(pdev, SMBHSTCFG, temp & 0xfe);
	pci_write_config_word(pdev, id->driver_data, vt596_smba);
	pci_write_config_byte(pdev, SMBHSTCFG, temp \| 0x01);
	dev_warn(&pdev->dev, "WARNING: SMBus interface set to new "
	"address 0x%04x!\n", vt596_smba);
	} else if ((temp & 1) == 0) {
	if (force) {
	/* NOTE: This assumes I/O space and other allocations
	* WERE done by the Bios! Don't complain if your
	* hardware does weird things after enabling this.
	* :') Check for Bios updates before resorting to
	* this.
	*/
	pci_write_config_byte(pdev, SMBHSTCFG, temp \| 1);
	dev_info(&pdev->dev, "Enabling SMBus device\n");
	} else {
	dev_err(&pdev->dev, "SMBUS: Error: Host SMBus "
	"controller not enabled! - upgrade BIOS or "
	"use force=1\n");
	goto release_region;
	}
	}

	if ((temp & 0x0E) == 8)
	dev_dbg(&pdev->dev, "using Interrupt 9 for SMBus.\n");
	else if ((temp & 0x0E) == 0)
	dev_dbg(&pdev->dev, "using Interrupt SMI# for SMBus.\n");
	else
	dev_dbg(&pdev->dev, "Illegal Interrupt configuration "
	"(or code out of date)!\n");

	pci_read_config_byte(pdev, SMBREV, &temp);
	dev_dbg(&pdev->dev, "SMBREV = 0x%X\n", temp);
	dev_dbg(&pdev->dev, "VT596_smba = 0x%X\n", vt596_smba);

	vt596_adapter.dev.parent = &pdev->dev;
	snprintf(vt596_adapter.name, I2C_NAME_SIZE,
	"SMBus Via Pro adapter at %04x", vt596_smba);

	vt596_pdev = pci_dev_get(pdev);
	if (i2c_add_adapter(&vt596_adapter)) {
	pci_dev_put(vt596_pdev);
	vt596_pdev = NULL;
	}

	/* Always return failure here. This is to allow other drivers to bind
	* to this pci device. We don't really want to have control over the
	* pci device, we only wanted to read as few register values from it.
	*/
	return -ENODEV;

	release_region:
	release_region(vt596_smba, 8);
	return error;
	}

	static struct pci_device_id vt596_ids[] = {
	{ PCI_DEVICE(PCI_VENDOR_ID_VIA, PCI_DEVICE_ID_VIA_82C596_3),
	.driver_data = SMBBA1 },
	{ PCI_DEVICE(PCI_VENDOR_ID_VIA, PCI_DEVICE_ID_VIA_82C596B_3),
	.driver_data = SMBBA1 },
	{ PCI_DEVICE(PCI_VENDOR_ID_VIA, PCI_DEVICE_ID_VIA_82C686_4),
	.driver_data = SMBBA1 },
	{ PCI_DEVICE(PCI_VENDOR_ID_VIA, PCI_DEVICE_ID_VIA_8233_0),
	.driver_data = SMBBA3 },
	{ PCI_DEVICE(PCI_VENDOR_ID_VIA, PCI_DEVICE_ID_VIA_8233A),
	.driver_data = SMBBA3 },
	{ PCI_DEVICE(PCI_VENDOR_ID_VIA, PCI_DEVICE_ID_VIA_8235),
	.driver_data = SMBBA3 },
	{ PCI_DEVICE(PCI_VENDOR_ID_VIA, PCI_DEVICE_ID_VIA_8237),
	.driver_data = SMBBA3 },
	{ PCI_DEVICE(PCI_VENDOR_ID_VIA, PCI_DEVICE_ID_VIA_8231_4),
	.driver_data = SMBBA1 },
	{ 0, }
	};

	MODULE_DEVICE_TABLE (pci, vt596_ids);

	static struct pci_driver vt596_driver = {
	.name = "vt596_smbus",
	.id_table = vt596_ids,
	.probe = vt596_probe,
	};

	static int __init i2c_vt596_init(void)
	{
	return pci_register_driver(&vt596_driver);
	}


	static void __exit i2c_vt596_exit(void)
	{
	pci_unregister_driver(&vt596_driver);
	if (vt596_pdev != NULL) {
	i2c_del_adapter(&vt596_adapter);
	release_region(vt596_smba, 8);
	pci_dev_put(vt596_pdev);
	vt596_pdev = NULL;
	}
	}

	MODULE_AUTHOR(
	"Frodo Looijaard <frodol@dds.nl> and "
	"Philip Edelbrock <phil@netroedge.com>");
	MODULE_DESCRIPTION("vt82c596 SMBus driver");
	MODULE_LICENSE("GPL");

	module_init(i2c_vt596_init);
	module_exit(i2c_vt596_exit);