/*
      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.
  */
  
  /*
     Status: beta
  
     Supports:
  	SIS 630
  	SIS 730
  	SIS 964
  
     Notable differences between chips:
  	+------------------------+--------------------+-------------------+
  	|                        |     SIS630/730     |      SIS964       |
  	+------------------------+--------------------+-------------------+
  	| Clock                  | 14kHz/56kHz        | 55.56kHz/27.78kHz |
  	| SMBus registers offset | 0x80               | 0xE0              |
  	| SMB_CNT                | Bit 1 = Slave Busy | Bit 1 = Bus probe |
  	|         (not used yet) | Bit 3 is reserved  | Bit 3 = Last byte |
  	| SMB_PCOUNT		 | Offset + 0x06      | Offset + 0x14     |
  	| SMB_COUNT              | 4:0 bits           | 5:0 bits          |
  	+------------------------+--------------------+-------------------+
  	(Other differences don't affect the functions provided by the driver)
  
     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/i2c.h>
  #include <linux/acpi.h>
  #include <linux/io.h>
  
  /* SIS964 id is defined here as we are the only file using it */
  #define PCI_DEVICE_ID_SI_964	0x0964
  
  /* SIS630/730/964 SMBus registers */
  #define SMB_STS			0x00	/* status */
  #define SMB_CNT			0x02	/* control */
  #define SMBHOST_CNT		0x03	/* host control */
  #define SMB_ADDR		0x04	/* address */
  #define SMB_CMD			0x05	/* command */
  #define SMB_COUNT		0x07	/* byte count */
  #define SMB_BYTE		0x08	/* ~0x8F data byte field */
  
  /* SMB_STS register */
  #define BYTE_DONE_STS		0x10	/* Byte Done Status / Block Array */
  #define SMBCOL_STS		0x04	/* Collision */
  #define SMBERR_STS		0x02	/* Device error */
  
  /* SMB_CNT register */
  #define MSTO_EN			0x40	/* Host Master Timeout Enable */
  #define SMBCLK_SEL		0x20	/* Host master clock selection */
  #define SMB_PROBE		0x02	/* Bus Probe/Slave busy */
  #define SMB_HOSTBUSY		0x01	/* Host Busy */
  
  /* SMBHOST_CNT register */
  #define SMB_KILL		0x20	/* Kill */
  #define SMB_START		0x10	/* Start */
  
  /* register count for request_region
   * As we don't use SMB_PCOUNT, 20 is ok for SiS630 and SiS964
   */
  #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) (SIS630/730 only).");
  module_param(force, bool, 0);
  MODULE_PARM_DESC(force, "Forcibly enable the SIS630. DANGEROUS!");
  
  /* SMBus base adress */
  static unsigned short smbus_base;
  
  /* supported chips */
  static int supported[] = {
  	PCI_DEVICE_ID_SI_630,
  	PCI_DEVICE_ID_SI_730,
  	PCI_DEVICE_ID_SI_760,
  	0 /* terminates the list */
  };
  
  static inline u8 sis630_read(u8 reg)
  {
  	return inb(smbus_base + reg);
  }
  
  static inline void sis630_write(u8 reg, u8 data)
  {
  	outb(data, smbus_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. */
  	temp = sis630_read(SMB_CNT);
  	if ((temp & (SMB_PROBE | SMB_HOSTBUSY)) != 0x00) {
  		dev_dbg(&adap->dev, "SMBus busy (%02x). Resetting...
  ", temp);
  		/* kill smbus transaction */
  		sis630_write(SMBHOST_CNT, SMB_KILL);
  
  		temp = sis630_read(SMB_CNT);
  		if (temp & (SMB_PROBE | SMB_HOSTBUSY)) {
  			dev_dbg(&adap->dev, "Failed! (%02x)
  ", temp);
  			return -EBUSY;
  		} else {
  			dev_dbg(&adap->dev, "Successful!
  ");
  		}
  	}
  
  	/* save old clock, so we can prevent machine for hung */
  	*oldclock = sis630_read(SMB_CNT);
  
  	dev_dbg(&adap->dev, "saved clock 0x%02x
  ", *oldclock);
  
  	/* disable timeout interrupt,
  	 * set Host Master Clock to 56KHz if requested */
  	if (high_clock)
  		sis630_write(SMB_CNT, SMBCLK_SEL);
  	else
  		sis630_write(SMB_CNT, (*oldclock & ~MSTO_EN));
  
  	/* 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, SMB_START | (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 & BYTE_DONE_STS))
  			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!
  ");
  		result = -ETIMEDOUT;
  	}
  
  	if (temp & SMBERR_STS) {
  		dev_dbg(&adap->dev, "Error: Failed bus transaction
  ");
  		result = -ENXIO;
  	}
  
  	if (temp & SMBCOL_STS) {
  		dev_err(&adap->dev, "Bus collision!
  ");
  		result = -EAGAIN;
  	}
  
  	return result;
  }
  
  static void sis630_transaction_end(struct i2c_adapter *adap, u8 oldclock)
  {
  	/* clear all status "sticky" bits */
  	sis630_write(SMB_STS, 0xFF);
  
  	dev_dbg(&adap->dev,
  		"SMB_CNT before clock restore 0x%02x
  ", sis630_read(SMB_CNT));
  
  	/*
  	 * restore old Host Master Clock if high_clock is set
  	 * and oldclock was not 56KHz
  	 */
  	if (high_clock && !(oldclock & SMBCLK_SEL))
  		sis630_write(SMB_CNT, sis630_read(SMB_CNT) & ~SMBCLK_SEL);
  
  	dev_dbg(&adap->dev,
  		"SMB_CNT after clock restore 0x%02x
  ", 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
  ", 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
  ", 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
  ", len, i);
  				if (i > 8) {
  					dev_dbg(&adap->dev,
  						"clear smbary_sts"
  						" len=%d i=%d
  ", len, i);
  					/*
  					   If this is not first transaction,
  					   we must clear sticky bit.
  					   clear SMBARY_STS
  					*/
  					sis630_write(SMB_STS, BYTE_DONE_STS);
  				}
  				rc = sis630_transaction_wait(adap,
  						SIS630_BLOCK_DATA);
  				if (rc) {
  					dev_dbg(&adap->dev,
  						"trans_wait failed
  ");
  					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
  ");
  				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
  ", data->block[0]);
  
  			for (i = 0; i < 8 && len < data->block[0]; i++, len++) {
  				dev_dbg(&adap->dev,
  					"read i=%d len=%d
  ", i, len);
  				data->block[len + 1] = sis630_read(SMB_BYTE +
  								   i);
  			}
  
  			dev_dbg(&adap->dev,
  				"clear smbary_sts len=%d i=%d
  ", len, i);
  
  			/* clear SMBARY_STS */
  			sis630_write(SMB_STS, BYTE_DONE_STS);
  		} 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
  ", 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;
  	/* acpi base address */
  	unsigned short acpi_base;
  
  	/* check for supported SiS devices */
  	for (i = 0; supported[i] > 0; i++) {
  		dummy = pci_get_device(PCI_VENDOR_ID_SI, supported[i], dummy);
  		if (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
  ");
  	} 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
  ");
  		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
  ");
  		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
  ");
  		retval = -ENODEV;
  		goto exit;
  	}
  
  	dev_dbg(&sis630_dev->dev, "ACPI base at 0x%04hx
  ", acpi_base);
  
  	if (supported[i] == PCI_DEVICE_ID_SI_760)
  		smbus_base = acpi_base + 0xE0;
  	else
  		smbus_base = acpi_base + 0x80;
  
  	dev_dbg(&sis630_dev->dev, "SMBus base at 0x%04hx
  ", smbus_base);
  
  	retval = acpi_check_region(smbus_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(smbus_base + SMB_STS, SIS630_SMB_IOREGION,
  			    sis630_driver.name)) {
  		dev_err(&sis630_dev->dev,
  			"I/O Region 0x%04hx-0x%04hx for SMBus already in use.
  ",
  			smbus_base + SMB_STS,
  			smbus_base + SMB_STS + SIS630_SMB_IOREGION - 1);
  		retval = -EBUSY;
  		goto exit;
  	}
  
  	retval = 0;
  
  exit:
  	if (retval)
  		smbus_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,
  	.retries	= 3
  };
  
  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) },
  	{ PCI_DEVICE(PCI_VENDOR_ID_SI, PCI_DEVICE_ID_SI_964) },
  	{ 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 compatible bus not detected, "
  			"module not inserted.
  ");
  		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 %04hx", smbus_base + SMB_STS);
  
  	return i2c_add_adapter(&sis630_adapter);
  }
  
  static void sis630_remove(struct pci_dev *dev)
  {
  	if (smbus_base) {
  		i2c_del_adapter(&sis630_adapter);
  		release_region(smbus_base + SMB_STS, SIS630_SMB_IOREGION);
  		smbus_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");