/*
    Copyright (c) 1998 - 2002 Frodo Looijaard <frodol@dds.nl> and
    Philip Edelbrock <phil@netroedge.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:
	Intel PIIX4, 440MX
	Serverworks OSB4, CSB5, CSB6, HT-1000
	ATI IXP200, IXP300, IXP400, SB600, SB700, SB800
	SMSC Victory66

   Note: we assume there can only be one device, with one SMBus interface.
*/

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


/* PIIX4 SMBus address offsets */
#define SMBHSTSTS	(0 + piix4_smba)
#define SMBHSLVSTS	(1 + piix4_smba)
#define SMBHSTCNT	(2 + piix4_smba)
#define SMBHSTCMD	(3 + piix4_smba)
#define SMBHSTADD	(4 + piix4_smba)
#define SMBHSTDAT0	(5 + piix4_smba)
#define SMBHSTDAT1	(6 + piix4_smba)
#define SMBBLKDAT	(7 + piix4_smba)
#define SMBSLVCNT	(8 + piix4_smba)
#define SMBSHDWCMD	(9 + piix4_smba)
#define SMBSLVEVT	(0xA + piix4_smba)
#define SMBSLVDAT	(0xC + piix4_smba)

/* count for request_region */
#define SMBIOSIZE	8

/* PCI Address Constants */
#define SMBBA		0x090
#define SMBHSTCFG	0x0D2
#define SMBSLVC		0x0D3
#define SMBSHDW1	0x0D4
#define SMBSHDW2	0x0D5
#define SMBREV		0x0D6

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

/* PIIX4 constants */
#define PIIX4_QUICK		0x00
#define PIIX4_BYTE		0x04
#define PIIX4_BYTE_DATA		0x08
#define PIIX4_WORD_DATA		0x0C
#define PIIX4_BLOCK_DATA	0x14

/* insmod parameters */

/* If force is set to anything different from 0, we forcibly enable the
   PIIX4. DANGEROUS! */
static int force;
module_param (force, int, 0);
MODULE_PARM_DESC(force, "Forcibly enable the PIIX4. DANGEROUS!");

/* If force_addr is set to anything different from 0, we forcibly enable
   the PIIX4 at the given address. VERY DANGEROUS! */
static int force_addr;
module_param (force_addr, int, 0);
MODULE_PARM_DESC(force_addr,
		 "Forcibly enable the PIIX4 at the given address. "
		 "EXTREMELY DANGEROUS!");

static unsigned short piix4_smba;
static int srvrworks_csb5_delay;
static struct pci_driver piix4_driver;
static struct i2c_adapter piix4_adapter;

static struct dmi_system_id __devinitdata piix4_dmi_blacklist[] = {
	{
		.ident = "Sapphire AM2RD790",
		.matches = {
			DMI_MATCH(DMI_BOARD_VENDOR, "SAPPHIRE Inc."),
			DMI_MATCH(DMI_BOARD_NAME, "PC-AM2RD790"),
		},
	},
	{
		.ident = "DFI Lanparty UT 790FX",
		.matches = {
			DMI_MATCH(DMI_BOARD_VENDOR, "DFI Inc."),
			DMI_MATCH(DMI_BOARD_NAME, "LP UT 790FX"),
		},
	},
	{ }
};

/* The IBM entry is in a separate table because we only check it
   on Intel-based systems */
static struct dmi_system_id __devinitdata piix4_dmi_ibm[] = {
	{
		.ident = "IBM",
		.matches = { DMI_MATCH(DMI_SYS_VENDOR, "IBM"), },
	},
	{ },
};

static int __devinit piix4_setup(struct pci_dev *PIIX4_dev,
				const struct pci_device_id *id)
{
	unsigned char temp;

	if ((PIIX4_dev->vendor == PCI_VENDOR_ID_SERVERWORKS) &&
	    (PIIX4_dev->device == PCI_DEVICE_ID_SERVERWORKS_CSB5))
		srvrworks_csb5_delay = 1;

	/* On some motherboards, it was reported that accessing the SMBus
	   caused severe hardware problems */
	if (dmi_check_system(piix4_dmi_blacklist)) {
		dev_err(&PIIX4_dev->dev,
			"Accessing the SMBus on this system is unsafe!\n");
		return -EPERM;
	}

	/* Don't access SMBus on IBM systems which get corrupted eeproms */
	if (dmi_check_system(piix4_dmi_ibm) &&
			PIIX4_dev->vendor == PCI_VENDOR_ID_INTEL) {
		dev_err(&PIIX4_dev->dev, "IBM system detected; this module "
			"may corrupt your serial eeprom! Refusing to load "
			"module!\n");
		return -EPERM;
	}

	/* Determine the address of the SMBus areas */
	if (force_addr) {
		piix4_smba = force_addr & 0xfff0;
		force = 0;
	} else {
		pci_read_config_word(PIIX4_dev, SMBBA, &piix4_smba);
		piix4_smba &= 0xfff0;
		if(piix4_smba == 0) {
			dev_err(&PIIX4_dev->dev, "SMBus base address "
				"uninitialized - upgrade BIOS or use "
				"force_addr=0xaddr\n");
			return -ENODEV;
		}
	}

	if (acpi_check_region(piix4_smba, SMBIOSIZE, piix4_driver.name))
		return -EBUSY;

	if (!request_region(piix4_smba, SMBIOSIZE, piix4_driver.name)) {
		dev_err(&PIIX4_dev->dev, "SMBus region 0x%x already in use!\n",
			piix4_smba);
		return -EBUSY;
	}

	pci_read_config_byte(PIIX4_dev, SMBHSTCFG, &temp);

	/* If force_addr is set, we program the new address here. Just to make
	   sure, we disable the PIIX4 first. */
	if (force_addr) {
		pci_write_config_byte(PIIX4_dev, SMBHSTCFG, temp & 0xfe);
		pci_write_config_word(PIIX4_dev, SMBBA, piix4_smba);
		pci_write_config_byte(PIIX4_dev, SMBHSTCFG, temp | 0x01);
		dev_info(&PIIX4_dev->dev, "WARNING: SMBus interface set to "
			"new address %04x!\n", piix4_smba);
	} else if ((temp & 1) == 0) {
		if (force) {
			/* This should never need to be done, but has been
			 * noted that many Dell machines have the SMBus
			 * interface on the PIIX4 disabled!? 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(PIIX4_dev, SMBHSTCFG,
					      temp | 1);
			dev_printk(KERN_NOTICE, &PIIX4_dev->dev,
				"WARNING: SMBus interface has been "
				"FORCEFULLY ENABLED!\n");
		} else {
			dev_err(&PIIX4_dev->dev,
				"Host SMBus controller not enabled!\n");
			release_region(piix4_smba, SMBIOSIZE);
			piix4_smba = 0;
			return -ENODEV;
		}
	}

	if (((temp & 0x0E) == 8) || ((temp & 0x0E) == 2))
		dev_dbg(&PIIX4_dev->dev, "Using Interrupt 9 for SMBus.\n");
	else if ((temp & 0x0E) == 0)
		dev_dbg(&PIIX4_dev->dev, "Using Interrupt SMI# for SMBus.\n");
	else
		dev_err(&PIIX4_dev->dev, "Illegal Interrupt configuration "
			"(or code out of date)!\n");

	pci_read_config_byte(PIIX4_dev, SMBREV, &temp);
	dev_info(&PIIX4_dev->dev,
		 "SMBus Host Controller at 0x%x, revision %d\n",
		 piix4_smba, temp);

	return 0;
}

static int piix4_transaction(void)
{
	int temp;
	int result = 0;
	int timeout = 0;

	dev_dbg(&piix4_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)) != 0x00) {
		dev_dbg(&piix4_adapter.dev, "SMBus busy (%02x). "
			"Resetting...\n", temp);
		outb_p(temp, SMBHSTSTS);
		if ((temp = inb_p(SMBHSTSTS)) != 0x00) {
			dev_err(&piix4_adapter.dev, "Failed! (%02x)\n", temp);
			return -EBUSY;
		} else {
			dev_dbg(&piix4_adapter.dev, "Successful!\n");
		}
	}

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

	/* We will always wait for a fraction of a second! (See PIIX4 docs errata) */
	if (srvrworks_csb5_delay) /* Extra delay for SERVERWORKS_CSB5 */
		msleep(2);
	else
		msleep(1);

	while ((timeout++ < MAX_TIMEOUT) &&
	       ((temp = inb_p(SMBHSTSTS)) & 0x01))
		msleep(1);

	/* If the SMBus is still busy, we give up */
	if (timeout >= MAX_TIMEOUT) {
		dev_err(&piix4_adapter.dev, "SMBus Timeout!\n");
		result = -ETIMEDOUT;
	}

	if (temp & 0x10) {
		result = -EIO;
		dev_err(&piix4_adapter.dev, "Error: Failed bus transaction\n");
	}

	if (temp & 0x08) {
		result = -EIO;
		dev_dbg(&piix4_adapter.dev, "Bus collision! SMBus may be "
			"locked until next hard reset. (sorry!)\n");
		/* Clock stops and slave is stuck in mid-transmission */
	}

	if (temp & 0x04) {
		result = -ENXIO;
		dev_dbg(&piix4_adapter.dev, "Error: no response!\n");
	}

	if (inb_p(SMBHSTSTS) != 0x00)
		outb_p(inb(SMBHSTSTS), SMBHSTSTS);

	if ((temp = inb_p(SMBHSTSTS)) != 0x00) {
		dev_err(&piix4_adapter.dev, "Failed reset at end of "
			"transaction (%02x)\n", temp);
	}
	dev_dbg(&piix4_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 negative errno on error. */
static s32 piix4_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;
	int status;

	switch (size) {
	case I2C_SMBUS_QUICK:
		outb_p((addr << 1) | read_write,
		       SMBHSTADD);
		size = PIIX4_QUICK;
		break;
	case I2C_SMBUS_BYTE:
		outb_p((addr << 1) | read_write,
		       SMBHSTADD);
		if (read_write == I2C_SMBUS_WRITE)
			outb_p(command, SMBHSTCMD);
		size = PIIX4_BYTE;
		break;
	case I2C_SMBUS_BYTE_DATA:
		outb_p((addr << 1) | read_write,
		       SMBHSTADD);
		outb_p(command, SMBHSTCMD);
		if (read_write == I2C_SMBUS_WRITE)
			outb_p(data->byte, SMBHSTDAT0);
		size = PIIX4_BYTE_DATA;
		break;
	case I2C_SMBUS_WORD_DATA:
		outb_p((addr << 1) | read_write,
		       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 = PIIX4_WORD_DATA;
		break;
	case I2C_SMBUS_BLOCK_DATA:
		outb_p((addr << 1) | read_write,
		       SMBHSTADD);
		outb_p(command, SMBHSTCMD);
		if (read_write == I2C_SMBUS_WRITE) {
			len = data->block[0];
			if (len == 0 || len > I2C_SMBUS_BLOCK_MAX)
				return -EINVAL;
			outb_p(len, SMBHSTDAT0);
			i = inb_p(SMBHSTCNT);	/* Reset SMBBLKDAT */
			for (i = 1; i <= len; i++)
				outb_p(data->block[i], SMBBLKDAT);
		}
		size = PIIX4_BLOCK_DATA;
		break;
	default:
		dev_warn(&adap->dev, "Unsupported transaction %d\n", size);
		return -EOPNOTSUPP;
	}

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

	status = piix4_transaction();
	if (status)
		return status;

	if ((read_write == I2C_SMBUS_WRITE) || (size == PIIX4_QUICK))
		return 0;


	switch (size) {
	case PIIX4_BYTE:
	case PIIX4_BYTE_DATA:
		data->byte = inb_p(SMBHSTDAT0);
		break;
	case PIIX4_WORD_DATA:
		data->word = inb_p(SMBHSTDAT0) + (inb_p(SMBHSTDAT1) << 8);
		break;
	case PIIX4_BLOCK_DATA:
		data->block[0] = inb_p(SMBHSTDAT0);
		if (data->block[0] == 0 || data->block[0] > I2C_SMBUS_BLOCK_MAX)
			return -EPROTO;
		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 piix4_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 const struct i2c_algorithm smbus_algorithm = {
	.smbus_xfer	= piix4_access,
	.functionality	= piix4_func,
};

static struct i2c_adapter piix4_adapter = {
	.owner		= THIS_MODULE,
	.id		= I2C_HW_SMBUS_PIIX4,
	.class		= I2C_CLASS_HWMON | I2C_CLASS_SPD,
	.algo		= &smbus_algorithm,
};

static struct pci_device_id piix4_ids[] = {
	{ PCI_DEVICE(PCI_VENDOR_ID_INTEL, PCI_DEVICE_ID_INTEL_82371AB_3) },
	{ PCI_DEVICE(PCI_VENDOR_ID_INTEL, PCI_DEVICE_ID_INTEL_82443MX_3) },
	{ PCI_DEVICE(PCI_VENDOR_ID_EFAR, PCI_DEVICE_ID_EFAR_SLC90E66_3) },
	{ PCI_DEVICE(PCI_VENDOR_ID_ATI, PCI_DEVICE_ID_ATI_IXP200_SMBUS) },
	{ PCI_DEVICE(PCI_VENDOR_ID_ATI, PCI_DEVICE_ID_ATI_IXP300_SMBUS) },
	{ PCI_DEVICE(PCI_VENDOR_ID_ATI, PCI_DEVICE_ID_ATI_IXP400_SMBUS) },
	{ PCI_DEVICE(PCI_VENDOR_ID_ATI, PCI_DEVICE_ID_ATI_SBX00_SMBUS) },
	{ PCI_DEVICE(PCI_VENDOR_ID_SERVERWORKS,
		     PCI_DEVICE_ID_SERVERWORKS_OSB4) },
	{ PCI_DEVICE(PCI_VENDOR_ID_SERVERWORKS,
		     PCI_DEVICE_ID_SERVERWORKS_CSB5) },
	{ PCI_DEVICE(PCI_VENDOR_ID_SERVERWORKS,
		     PCI_DEVICE_ID_SERVERWORKS_CSB6) },
	{ PCI_DEVICE(PCI_VENDOR_ID_SERVERWORKS,
		     PCI_DEVICE_ID_SERVERWORKS_HT1000SB) },
	{ 0, }
};

MODULE_DEVICE_TABLE (pci, piix4_ids);

static int __devinit piix4_probe(struct pci_dev *dev,
				const struct pci_device_id *id)
{
	int retval;

	retval = piix4_setup(dev, id);
	if (retval)
		return retval;

	/* set up the sysfs linkage to our parent device */
	piix4_adapter.dev.parent = &dev->dev;

	snprintf(piix4_adapter.name, sizeof(piix4_adapter.name),
		"SMBus PIIX4 adapter at %04x", piix4_smba);

	if ((retval = i2c_add_adapter(&piix4_adapter))) {
		dev_err(&dev->dev, "Couldn't register adapter!\n");
		release_region(piix4_smba, SMBIOSIZE);
		piix4_smba = 0;
	}

	return retval;
}

static void __devexit piix4_remove(struct pci_dev *dev)
{
	if (piix4_smba) {
		i2c_del_adapter(&piix4_adapter);
		release_region(piix4_smba, SMBIOSIZE);
		piix4_smba = 0;
	}
}

static struct pci_driver piix4_driver = {
	.name		= "piix4_smbus",
	.id_table	= piix4_ids,
	.probe		= piix4_probe,
	.remove		= __devexit_p(piix4_remove),
};

static int __init i2c_piix4_init(void)
{
	return pci_register_driver(&piix4_driver);
}

static void __exit i2c_piix4_exit(void)
{
	pci_unregister_driver(&piix4_driver);
}

MODULE_AUTHOR("Frodo Looijaard <frodol@dds.nl> and "
		"Philip Edelbrock <phil@netroedge.com>");
MODULE_DESCRIPTION("PIIX4 SMBus driver");
MODULE_LICENSE("GPL");

module_init(i2c_piix4_init);
module_exit(i2c_piix4_exit);