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i2c-sis96x.c

/*
    sis96x.c - Part of lm_sensors, Linux kernel modules for hardware
              monitoring

    Copyright (c) 2003 Mark M. Hoffman <mhoffman@lightlink.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.
*/

/*
    This module must be considered BETA unless and until
    the chipset manufacturer releases a datasheet.
    The register definitions are based on the SiS630.

    This module relies on quirk_sis_96x_smbus (drivers/pci/quirks.c)
    for just about every machine for which users have reported.
    If this module isn't detecting your 96x south bridge, have a 
    look there.

    We assume there can only be one SiS96x with one SMBus interface.
*/

#include <linux/module.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 <asm/io.h>

/* base address register in PCI config space */
#define SIS96x_BAR 0x04

/* SiS96x SMBus registers */
#define SMB_STS      0x00
#define SMB_EN       0x01
#define SMB_CNT      0x02
#define SMB_HOST_CNT 0x03
#define SMB_ADDR     0x04
#define SMB_CMD      0x05
#define SMB_PCOUNT   0x06
#define SMB_COUNT    0x07
#define SMB_BYTE     0x08
#define SMB_DEV_ADDR 0x10
#define SMB_DB0      0x11
#define SMB_DB1      0x12
#define SMB_SAA      0x13

/* register count for request_region */
#define SMB_IOSIZE 0x20

/* Other settings */
#define MAX_TIMEOUT 500

/* SiS96x SMBus constants */
#define SIS96x_QUICK      0x00
#define SIS96x_BYTE       0x01
#define SIS96x_BYTE_DATA  0x02
#define SIS96x_WORD_DATA  0x03
#define SIS96x_PROC_CALL  0x04
#define SIS96x_BLOCK_DATA 0x05

static struct pci_driver sis96x_driver;
static struct i2c_adapter sis96x_adapter;
static u16 sis96x_smbus_base;

static inline u8 sis96x_read(u8 reg)
{
      return inb(sis96x_smbus_base + reg) ;
}

static inline void sis96x_write(u8 reg, u8 data)
{
      outb(data, sis96x_smbus_base + reg) ;
}

/* Execute a SMBus transaction.
   int size is from SIS96x_QUICK to SIS96x_BLOCK_DATA
 */
static int sis96x_transaction(int size)
{
      int temp;
      int result = 0;
      int timeout = 0;

      dev_dbg(&sis96x_adapter.dev, "SMBus transaction %d\n", size);

      /* Make sure the SMBus host is ready to start transmitting */
      if (((temp = sis96x_read(SMB_CNT)) & 0x03) != 0x00) {

            dev_dbg(&sis96x_adapter.dev, "SMBus busy (0x%02x). "
                  "Resetting...\n", temp);

            /* kill the transaction */
            sis96x_write(SMB_HOST_CNT, 0x20);

            /* check it again */
            if (((temp = sis96x_read(SMB_CNT)) & 0x03) != 0x00) {
                  dev_dbg(&sis96x_adapter.dev, "Failed (0x%02x)\n", temp);
                  return -1;
            } else {
                  dev_dbg(&sis96x_adapter.dev, "Successful\n");
            }
      }

      /* Turn off timeout interrupts, set fast host clock */
      sis96x_write(SMB_CNT, 0x20);

      /* clear all (sticky) status flags */
      temp = sis96x_read(SMB_STS);
      sis96x_write(SMB_STS, temp & 0x1e);

      /* start the transaction by setting bit 4 and size bits */
      sis96x_write(SMB_HOST_CNT, 0x10 | (size & 0x07));

      /* We will always wait for a fraction of a second! */
      do {
            msleep(1);
            temp = sis96x_read(SMB_STS);
      } while (!(temp & 0x0e) && (timeout++ < MAX_TIMEOUT));

      /* If the SMBus is still busy, we give up */
      if (timeout >= MAX_TIMEOUT) {
            dev_dbg(&sis96x_adapter.dev, "SMBus Timeout! (0x%02x)\n", temp);
            result = -1;
      }

      /* device error - probably missing ACK */
      if (temp & 0x02) {
            dev_dbg(&sis96x_adapter.dev, "Failed bus transaction!\n");
            result = -1;
      }

      /* bus collision */
      if (temp & 0x04) {
            dev_dbg(&sis96x_adapter.dev, "Bus collision!\n");
            result = -1;
      }

      /* Finish up by resetting the bus */
      sis96x_write(SMB_STS, temp);
      if ((temp = sis96x_read(SMB_STS))) {
            dev_dbg(&sis96x_adapter.dev, "Failed reset at "
                  "end of transaction! (0x%02x)\n", temp);
      }

      return result;
}

/* Return -1 on error. */
static s32 sis96x_access(struct i2c_adapter * adap, u16 addr,
                   unsigned short flags, char read_write,
                   u8 command, int size, union i2c_smbus_data * data)
{

      switch (size) {
      case I2C_SMBUS_QUICK:
            sis96x_write(SMB_ADDR, ((addr & 0x7f) << 1) | (read_write & 0x01));
            size = SIS96x_QUICK;
            break;

      case I2C_SMBUS_BYTE:
            sis96x_write(SMB_ADDR, ((addr & 0x7f) << 1) | (read_write & 0x01));
            if (read_write == I2C_SMBUS_WRITE)
                  sis96x_write(SMB_CMD, command);
            size = SIS96x_BYTE;
            break;

      case I2C_SMBUS_BYTE_DATA:
            sis96x_write(SMB_ADDR, ((addr & 0x7f) << 1) | (read_write & 0x01));
            sis96x_write(SMB_CMD, command);
            if (read_write == I2C_SMBUS_WRITE)
                  sis96x_write(SMB_BYTE, data->byte);
            size = SIS96x_BYTE_DATA;
            break;

      case I2C_SMBUS_PROC_CALL:
      case I2C_SMBUS_WORD_DATA:
            sis96x_write(SMB_ADDR, ((addr & 0x7f) << 1) | (read_write & 0x01));
            sis96x_write(SMB_CMD, command);
            if (read_write == I2C_SMBUS_WRITE) {
                  sis96x_write(SMB_BYTE, data->word & 0xff);
                  sis96x_write(SMB_BYTE + 1, (data->word & 0xff00) >> 8);
            }
            size = (size == I2C_SMBUS_PROC_CALL ? 
                  SIS96x_PROC_CALL : SIS96x_WORD_DATA);
            break;

      case I2C_SMBUS_BLOCK_DATA:
            /* TO DO: */
            dev_info(&adap->dev, "SMBus block not implemented!\n");
            return -1;
            break;

      default:
            dev_info(&adap->dev, "Unsupported I2C size\n");
            return -1;
            break;
      }

      if (sis96x_transaction(size))
            return -1;

      if ((size != SIS96x_PROC_CALL) &&
            ((read_write == I2C_SMBUS_WRITE) || (size == SIS96x_QUICK)))
            return 0;

      switch (size) {
      case SIS96x_BYTE:
      case SIS96x_BYTE_DATA:
            data->byte = sis96x_read(SMB_BYTE);
            break;

      case SIS96x_WORD_DATA:
      case SIS96x_PROC_CALL:
            data->word = sis96x_read(SMB_BYTE) +
                        (sis96x_read(SMB_BYTE + 1) << 8);
            break;
      }
      return 0;
}

static u32 sis96x_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;
}

static const struct i2c_algorithm smbus_algorithm = {
      .smbus_xfer = sis96x_access,
      .functionality    = sis96x_func,
};

static struct i2c_adapter sis96x_adapter = {
      .owner            = THIS_MODULE,
      .id         = I2C_HW_SMBUS_SIS96X,
      .class            = I2C_CLASS_HWMON,
      .algo       = &smbus_algorithm,
};

static struct pci_device_id sis96x_ids[] = {
      { PCI_DEVICE(PCI_VENDOR_ID_SI, PCI_DEVICE_ID_SI_SMBUS) },
      { 0, }
};

MODULE_DEVICE_TABLE (pci, sis96x_ids);

static int __devinit sis96x_probe(struct pci_dev *dev,
                        const struct pci_device_id *id)
{
      u16 ww = 0;
      int retval;

      if (sis96x_smbus_base) {
            dev_err(&dev->dev, "Only one device supported.\n");
            return -EBUSY;
      }

      pci_read_config_word(dev, PCI_CLASS_DEVICE, &ww);
      if (PCI_CLASS_SERIAL_SMBUS != ww) {
            dev_err(&dev->dev, "Unsupported device class 0x%04x!\n", ww);
            return -ENODEV;
      }

      sis96x_smbus_base = pci_resource_start(dev, SIS96x_BAR);
      if (!sis96x_smbus_base) {
            dev_err(&dev->dev, "SiS96x SMBus base address "
                  "not initialized!\n");
            return -EINVAL;
      }
      dev_info(&dev->dev, "SiS96x SMBus base address: 0x%04x\n",
                  sis96x_smbus_base);

      /* Everything is happy, let's grab the memory and set things up. */
      if (!request_region(sis96x_smbus_base, SMB_IOSIZE,
                      sis96x_driver.name)) {
            dev_err(&dev->dev, "SMBus registers 0x%04x-0x%04x "
                  "already in use!\n", sis96x_smbus_base,
                  sis96x_smbus_base + SMB_IOSIZE - 1);

            sis96x_smbus_base = 0;
            return -EINVAL;
      }

      /* set up the sysfs linkage to our parent device */
      sis96x_adapter.dev.parent = &dev->dev;

      snprintf(sis96x_adapter.name, sizeof(sis96x_adapter.name),
            "SiS96x SMBus adapter at 0x%04x", sis96x_smbus_base);

      if ((retval = i2c_add_adapter(&sis96x_adapter))) {
            dev_err(&dev->dev, "Couldn't register adapter!\n");
            release_region(sis96x_smbus_base, SMB_IOSIZE);
            sis96x_smbus_base = 0;
      }

      return retval;
}

static void __devexit sis96x_remove(struct pci_dev *dev)
{
      if (sis96x_smbus_base) {
            i2c_del_adapter(&sis96x_adapter);
            release_region(sis96x_smbus_base, SMB_IOSIZE);
            sis96x_smbus_base = 0;
      }
}

static struct pci_driver sis96x_driver = {
      .name       = "sis96x_smbus",
      .id_table   = sis96x_ids,
      .probe            = sis96x_probe,
      .remove           = __devexit_p(sis96x_remove),
};

static int __init i2c_sis96x_init(void)
{
      return pci_register_driver(&sis96x_driver);
}

static void __exit i2c_sis96x_exit(void)
{
      pci_unregister_driver(&sis96x_driver);
}

MODULE_AUTHOR("Mark M. Hoffman <mhoffman@lightlink.com>");
MODULE_DESCRIPTION("SiS96x SMBus driver");
MODULE_LICENSE("GPL");

/* Register initialization functions using helper macros */
module_init(i2c_sis96x_init);
module_exit(i2c_sis96x_exit);


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