/*
    Copyright (c) 2002,2003 Alexander Malysh <amalysh@web.de>

    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.
*/

/*
   Changes:
   24.08.2002
   	Fixed the typo in sis630_access (Thanks to Mark M. Hoffman)
	Changed sis630_transaction.(Thanks to Mark M. Hoffman)
   18.09.2002
	Added SIS730 as supported.
   21.09.2002
	Added high_clock module option.If this option is set
	used Host Master Clock 56KHz (default 14KHz).For now we save old Host
	Master Clock and after transaction completed restore (otherwise
	it's confuse BIOS and hung Machine).
   24.09.2002
	Fixed typo in sis630_access
	Fixed logical error by restoring of Host Master Clock
   31.07.2003
   	Added block data read/write support.
*/

/*
   Status: beta

   Supports:
	SIS 630
	SIS 730

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

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

/* SIS630 SMBus registers */
#define SMB_STS			0x80	/* status */
#define SMB_EN			0x81	/* status enable */
#define SMB_CNT			0x82
#define SMBHOST_CNT		0x83
#define SMB_ADDR		0x84
#define SMB_CMD			0x85
#define SMB_PCOUNT		0x86	/* processed count */
#define SMB_COUNT		0x87
#define SMB_BYTE		0x88	/* ~0x8F data byte field */
#define SMBDEV_ADDR		0x90
#define SMB_DB0			0x91
#define SMB_DB1			0x92
#define SMB_SAA			0x93

/* register count for request_region */
#define SIS630_SMB_IOREGION	20

/* PCI address constants */
/* acpi base address register  */
#define SIS630_ACPI_BASE_REG	0x74
/* bios control register */
#define SIS630_BIOS_CTL_REG	0x40

/* Other settings */
#define MAX_TIMEOUT		500

/* SIS630 constants */
#define SIS630_QUICK		0x00
#define SIS630_BYTE		0x01
#define SIS630_BYTE_DATA	0x02
#define SIS630_WORD_DATA	0x03
#define SIS630_PCALL		0x04
#define SIS630_BLOCK_DATA	0x05

static struct pci_driver sis630_driver;

/* insmod parameters */
static bool high_clock;
static bool force;
module_param(high_clock, bool, 0);
MODULE_PARM_DESC(high_clock, "Set Host Master Clock to 56KHz (default 14KHz).");
module_param(force, bool, 0);
MODULE_PARM_DESC(force, "Forcibly enable the SIS630. DANGEROUS!");

/* acpi base address */
static unsigned short acpi_base;

/* supported chips */
static int supported[] = {
	PCI_DEVICE_ID_SI_630,
	PCI_DEVICE_ID_SI_730,
	0 /* terminates the list */
};

static inline u8 sis630_read(u8 reg)
{
	return inb(acpi_base + reg);
}

static inline void sis630_write(u8 reg, u8 data)
{
	outb(data, acpi_base + reg);
}

static int sis630_transaction_start(struct i2c_adapter *adap, int size, u8 *oldclock)
{
        int temp;

	/* Make sure the SMBus host is ready to start transmitting. */
	if ((temp = sis630_read(SMB_CNT) & 0x03) != 0x00) {
		dev_dbg(&adap->dev, "SMBus busy (%02x).Resetting...\n",temp);
		/* kill smbus transaction */
		sis630_write(SMBHOST_CNT, 0x20);

		if ((temp = sis630_read(SMB_CNT) & 0x03) != 0x00) {
			dev_dbg(&adap->dev, "Failed! (%02x)\n", temp);
			return -EBUSY;
                } else {
			dev_dbg(&adap->dev, "Successful!\n");
		}
        }

	/* save old clock, so we can prevent machine for hung */
	*oldclock = sis630_read(SMB_CNT);

	dev_dbg(&adap->dev, "saved clock 0x%02x\n", *oldclock);

	/* disable timeout interrupt , set Host Master Clock to 56KHz if requested */
	if (high_clock)
		sis630_write(SMB_CNT, 0x20);
	else
		sis630_write(SMB_CNT, (*oldclock & ~0x40));

	/* clear all sticky bits */
	temp = sis630_read(SMB_STS);
	sis630_write(SMB_STS, temp & 0x1e);

	/* start the transaction by setting bit 4 and size */
	sis630_write(SMBHOST_CNT,0x10 | (size & 0x07));

	return 0;
}

static int sis630_transaction_wait(struct i2c_adapter *adap, int size)
{
	int temp, result = 0, timeout = 0;

	/* We will always wait for a fraction of a second! */
	do {
		msleep(1);
		temp = sis630_read(SMB_STS);
		/* check if block transmitted */
		if (size == SIS630_BLOCK_DATA && (temp & 0x10))
			break;
	} while (!(temp & 0x0e) && (timeout++ < MAX_TIMEOUT));

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

	if (temp & 0x02) {
		dev_dbg(&adap->dev, "Error: Failed bus transaction\n");
		result = -ENXIO;
	}

	if (temp & 0x04) {
		dev_err(&adap->dev, "Bus collision!\n");
		result = -EIO;
		/*
		  TBD: Datasheet say:
		  the software should clear this bit and restart SMBUS operation.
		  Should we do it or user start request again?
		*/
	}

	return result;
}

static void sis630_transaction_end(struct i2c_adapter *adap, u8 oldclock)
{
	int temp = 0;

	/* clear all status "sticky" bits */
	sis630_write(SMB_STS, temp);

	dev_dbg(&adap->dev, "SMB_CNT before clock restore 0x%02x\n", sis630_read(SMB_CNT));

	/*
	 * restore old Host Master Clock if high_clock is set
	 * and oldclock was not 56KHz
	 */
	if (high_clock && !(oldclock & 0x20))
		sis630_write(SMB_CNT,(sis630_read(SMB_CNT) & ~0x20));

	dev_dbg(&adap->dev, "SMB_CNT after clock restore 0x%02x\n", sis630_read(SMB_CNT));
}

static int sis630_transaction(struct i2c_adapter *adap, int size)
{
	int result = 0;
	u8 oldclock = 0;

	result = sis630_transaction_start(adap, size, &oldclock);
	if (!result) {
		result = sis630_transaction_wait(adap, size);
		sis630_transaction_end(adap, oldclock);
	}

	return result;
}

static int sis630_block_data(struct i2c_adapter *adap, union i2c_smbus_data *data, int read_write)
{
	int i, len = 0, rc = 0;
	u8 oldclock = 0;

	if (read_write == I2C_SMBUS_WRITE) {
		len = data->block[0];
		if (len < 0)
			len = 0;
		else if (len > 32)
			len = 32;
		sis630_write(SMB_COUNT, len);
		for (i=1; i <= len; i++) {
			dev_dbg(&adap->dev, "set data 0x%02x\n", data->block[i]);
			/* set data */
			sis630_write(SMB_BYTE+(i-1)%8, data->block[i]);
			if (i==8 || (len<8 && i==len)) {
				dev_dbg(&adap->dev, "start trans len=%d i=%d\n",len ,i);
				/* first transaction */
				rc = sis630_transaction_start(adap,
						SIS630_BLOCK_DATA, &oldclock);
				if (rc)
					return rc;
			}
			else if ((i-1)%8 == 7 || i==len) {
				dev_dbg(&adap->dev, "trans_wait len=%d i=%d\n",len,i);
				if (i>8) {
					dev_dbg(&adap->dev, "clear smbary_sts len=%d i=%d\n",len,i);
					/*
					   If this is not first transaction,
					   we must clear sticky bit.
					   clear SMBARY_STS
					*/
					sis630_write(SMB_STS,0x10);
				}
				rc = sis630_transaction_wait(adap,
						SIS630_BLOCK_DATA);
				if (rc) {
					dev_dbg(&adap->dev, "trans_wait failed\n");
					break;
				}
			}
		}
	}
	else {
		/* read request */
		data->block[0] = len = 0;
		rc = sis630_transaction_start(adap,
				SIS630_BLOCK_DATA, &oldclock);
		if (rc)
			return rc;
		do {
			rc = sis630_transaction_wait(adap, SIS630_BLOCK_DATA);
			if (rc) {
				dev_dbg(&adap->dev, "trans_wait failed\n");
				break;
			}
			/* if this first transaction then read byte count */
			if (len == 0)
				data->block[0] = sis630_read(SMB_COUNT);

			/* just to be sure */
			if (data->block[0] > 32)
				data->block[0] = 32;

			dev_dbg(&adap->dev, "block data read len=0x%x\n", data->block[0]);

			for (i=0; i < 8 && len < data->block[0]; i++,len++) {
				dev_dbg(&adap->dev, "read i=%d len=%d\n", i, len);
				data->block[len+1] = sis630_read(SMB_BYTE+i);
			}

			dev_dbg(&adap->dev, "clear smbary_sts len=%d i=%d\n",len,i);

			/* clear SMBARY_STS */
			sis630_write(SMB_STS,0x10);
		} while(len < data->block[0]);
	}

	sis630_transaction_end(adap, oldclock);

	return rc;
}

/* Return negative errno on error. */
static s32 sis630_access(struct i2c_adapter *adap, u16 addr,
			 unsigned short flags, char read_write,
			 u8 command, int size, union i2c_smbus_data *data)
{
	int status;

	switch (size) {
		case I2C_SMBUS_QUICK:
			sis630_write(SMB_ADDR, ((addr & 0x7f) << 1) | (read_write & 0x01));
			size = SIS630_QUICK;
			break;
		case I2C_SMBUS_BYTE:
			sis630_write(SMB_ADDR, ((addr & 0x7f) << 1) | (read_write & 0x01));
			if (read_write == I2C_SMBUS_WRITE)
				sis630_write(SMB_CMD, command);
			size = SIS630_BYTE;
			break;
		case I2C_SMBUS_BYTE_DATA:
			sis630_write(SMB_ADDR, ((addr & 0x7f) << 1) | (read_write & 0x01));
			sis630_write(SMB_CMD, command);
			if (read_write == I2C_SMBUS_WRITE)
				sis630_write(SMB_BYTE, data->byte);
			size = SIS630_BYTE_DATA;
			break;
		case I2C_SMBUS_PROC_CALL:
		case I2C_SMBUS_WORD_DATA:
			sis630_write(SMB_ADDR,((addr & 0x7f) << 1) | (read_write & 0x01));
			sis630_write(SMB_CMD, command);
			if (read_write == I2C_SMBUS_WRITE) {
				sis630_write(SMB_BYTE, data->word & 0xff);
				sis630_write(SMB_BYTE + 1,(data->word & 0xff00) >> 8);
			}
			size = (size == I2C_SMBUS_PROC_CALL ? SIS630_PCALL : SIS630_WORD_DATA);
			break;
		case I2C_SMBUS_BLOCK_DATA:
			sis630_write(SMB_ADDR,((addr & 0x7f) << 1) | (read_write & 0x01));
			sis630_write(SMB_CMD, command);
			size = SIS630_BLOCK_DATA;
			return sis630_block_data(adap, data, read_write);
		default:
			dev_warn(&adap->dev, "Unsupported transaction %d\n",
				 size);
			return -EOPNOTSUPP;
	}

	status = sis630_transaction(adap, size);
	if (status)
		return status;

	if ((size != SIS630_PCALL) &&
		((read_write == I2C_SMBUS_WRITE) || (size == SIS630_QUICK))) {
		return 0;
	}

	switch(size) {
		case SIS630_BYTE:
		case SIS630_BYTE_DATA:
			data->byte = sis630_read(SMB_BYTE);
			break;
		case SIS630_PCALL:
		case SIS630_WORD_DATA:
			data->word = sis630_read(SMB_BYTE) + (sis630_read(SMB_BYTE + 1) << 8);
			break;
	}

	return 0;
}

static u32 sis630_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_PROC_CALL |
		I2C_FUNC_SMBUS_BLOCK_DATA;
}

static int sis630_setup(struct pci_dev *sis630_dev)
{
	unsigned char b;
	struct pci_dev *dummy = NULL;
	int retval, i;

	/* check for supported SiS devices */
	for (i=0; supported[i] > 0 ; i++) {
		if ((dummy = pci_get_device(PCI_VENDOR_ID_SI, supported[i], dummy)))
			break; /* found */
	}

	if (dummy) {
		pci_dev_put(dummy);
	}
        else if (force) {
		dev_err(&sis630_dev->dev, "WARNING: Can't detect SIS630 compatible device, but "
			"loading because of force option enabled\n");
 	}
	else {
		return -ENODEV;
	}

	/*
	   Enable ACPI first , so we can accsess reg 74-75
	   in acpi io space and read acpi base addr
	*/
	if (pci_read_config_byte(sis630_dev, SIS630_BIOS_CTL_REG,&b)) {
		dev_err(&sis630_dev->dev, "Error: Can't read bios ctl reg\n");
		retval = -ENODEV;
		goto exit;
	}
	/* if ACPI already enabled , do nothing */
	if (!(b & 0x80) &&
	    pci_write_config_byte(sis630_dev, SIS630_BIOS_CTL_REG, b | 0x80)) {
		dev_err(&sis630_dev->dev, "Error: Can't enable ACPI\n");
		retval = -ENODEV;
		goto exit;
	}

	/* Determine the ACPI base address */
	if (pci_read_config_word(sis630_dev,SIS630_ACPI_BASE_REG,&acpi_base)) {
		dev_err(&sis630_dev->dev, "Error: Can't determine ACPI base address\n");
		retval = -ENODEV;
		goto exit;
	}

	dev_dbg(&sis630_dev->dev, "ACPI base at 0x%04x\n", acpi_base);

	retval = acpi_check_region(acpi_base + SMB_STS, SIS630_SMB_IOREGION,
				   sis630_driver.name);
	if (retval)
		goto exit;

	/* Everything is happy, let's grab the memory and set things up. */
	if (!request_region(acpi_base + SMB_STS, SIS630_SMB_IOREGION,
			    sis630_driver.name)) {
		dev_err(&sis630_dev->dev, "SMBus registers 0x%04x-0x%04x already "
			"in use!\n", acpi_base + SMB_STS, acpi_base + SMB_SAA);
		retval = -EBUSY;
		goto exit;
	}

	retval = 0;

exit:
	if (retval)
		acpi_base = 0;
	return retval;
}


static const struct i2c_algorithm smbus_algorithm = {
	.smbus_xfer	= sis630_access,
	.functionality	= sis630_func,
};

static struct i2c_adapter sis630_adapter = {
	.owner		= THIS_MODULE,
	.class		= I2C_CLASS_HWMON | I2C_CLASS_SPD,
	.algo		= &smbus_algorithm,
};

static DEFINE_PCI_DEVICE_TABLE(sis630_ids) = {
	{ PCI_DEVICE(PCI_VENDOR_ID_SI, PCI_DEVICE_ID_SI_503) },
	{ PCI_DEVICE(PCI_VENDOR_ID_SI, PCI_DEVICE_ID_SI_LPC) },
	{ 0, }
};

MODULE_DEVICE_TABLE (pci, sis630_ids);

static int sis630_probe(struct pci_dev *dev, const struct pci_device_id *id)
{
	if (sis630_setup(dev)) {
		dev_err(&dev->dev, "SIS630 comp. bus not detected, module not inserted.\n");
		return -ENODEV;
	}

	/* set up the sysfs linkage to our parent device */
	sis630_adapter.dev.parent = &dev->dev;

	snprintf(sis630_adapter.name, sizeof(sis630_adapter.name),
		 "SMBus SIS630 adapter at %04x", acpi_base + SMB_STS);

	return i2c_add_adapter(&sis630_adapter);
}

static void sis630_remove(struct pci_dev *dev)
{
	if (acpi_base) {
		i2c_del_adapter(&sis630_adapter);
		release_region(acpi_base + SMB_STS, SIS630_SMB_IOREGION);
		acpi_base = 0;
	}
}


static struct pci_driver sis630_driver = {
	.name		= "sis630_smbus",
	.id_table	= sis630_ids,
	.probe		= sis630_probe,
	.remove		= sis630_remove,
};

module_pci_driver(sis630_driver);

MODULE_LICENSE("GPL");
MODULE_AUTHOR("Alexander Malysh <amalysh@web.de>");
MODULE_DESCRIPTION("SIS630 SMBus driver");