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    i2c-via.c - Part of lm_sensors,  Linux kernel modules
                for hardware monitoring

    i2c Support for Via Technologies 82C586B South Bridge

    Copyright (c) 1998, 1999 Kyösti Mälkki <kmalkki@cc.hut.fi>

    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
    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.

#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/pci.h>
#include <linux/ioport.h>
#include <linux/init.h>
#include <linux/i2c.h>
#include <linux/i2c-algo-bit.h>
#include <asm/io.h>

/* Power management registers */
#define PM_CFG_REVID    0x08  /* silicon revision code */
#define PM_CFG_IOBASE0  0x20
#define PM_CFG_IOBASE1  0x48

#define I2C_DIR         (pm_io_base+0x40)
#define I2C_OUT         (pm_io_base+0x42)
#define I2C_IN          (pm_io_base+0x44)
#define I2C_SCL         0x02  /* clock bit in DIR/OUT/IN register */
#define I2C_SDA         0x04

/* io-region reservation */
#define IOSPACE         0x06

static struct pci_driver vt586b_driver;
static u16 pm_io_base;

   It does not appear from the datasheet that the GPIO pins are
   open drain. So a we set a low value by setting the direction to
   output and a high value by setting the direction to input and
   relying on the required I2C pullup. The data value is initialized
   to 0 in via_init() and never changed.
static void bit_via_setscl(void *data, int state)
      outb(state ? inb(I2C_DIR) & ~I2C_SCL : inb(I2C_DIR) | I2C_SCL, I2C_DIR);

static void bit_via_setsda(void *data, int state)
      outb(state ? inb(I2C_DIR) & ~I2C_SDA : inb(I2C_DIR) | I2C_SDA, I2C_DIR);

static int bit_via_getscl(void *data)
      return (0 != (inb(I2C_IN) & I2C_SCL));

static int bit_via_getsda(void *data)
      return (0 != (inb(I2C_IN) & I2C_SDA));

static struct i2c_algo_bit_data bit_data = {
      .setsda           = bit_via_setsda,
      .setscl           = bit_via_setscl,
      .getsda           = bit_via_getsda,
      .getscl           = bit_via_getscl,
      .udelay           = 5,
      .timeout    = HZ

static struct i2c_adapter vt586b_adapter = {
      .owner            = THIS_MODULE,
      .id         = I2C_HW_B_VIA,
      .class          = I2C_CLASS_HWMON,
      .name       = "VIA i2c",
      .algo_data  = &bit_data,

static struct pci_device_id vt586b_ids[] __devinitdata = {
      { 0, }

MODULE_DEVICE_TABLE (pci, vt586b_ids);

static int __devinit vt586b_probe(struct pci_dev *dev, const struct pci_device_id *id)
      u16 base;
      u8 rev;
      int res;

      if (pm_io_base) {
            dev_err(&dev->dev, "i2c-via: Will only support one host\n");
            return -ENODEV;

      pci_read_config_byte(dev, PM_CFG_REVID, &rev);

      switch (rev) {
      case 0x00:
            base = PM_CFG_IOBASE0;
      case 0x01:
      case 0x10:
            base = PM_CFG_IOBASE1;

            base = PM_CFG_IOBASE1;
            /* later revision */

      pci_read_config_word(dev, base, &pm_io_base);
      pm_io_base &= (0xff << 8);

      if (!request_region(I2C_DIR, IOSPACE, vt586b_driver.name)) {
            dev_err(&dev->dev, "IO 0x%x-0x%x already in use\n", I2C_DIR, I2C_DIR + IOSPACE);
            return -ENODEV;

      outb(inb(I2C_DIR) & ~(I2C_SDA | I2C_SCL), I2C_DIR);
      outb(inb(I2C_OUT) & ~(I2C_SDA | I2C_SCL), I2C_OUT);

      /* set up the sysfs linkage to our parent device */
      vt586b_adapter.dev.parent = &dev->dev;

      res = i2c_bit_add_bus(&vt586b_adapter);
      if ( res < 0 ) {
            release_region(I2C_DIR, IOSPACE);
            pm_io_base = 0;
            return res;
      return 0;

static void __devexit vt586b_remove(struct pci_dev *dev)
      release_region(I2C_DIR, IOSPACE);
      pm_io_base = 0;

static struct pci_driver vt586b_driver = {
      .name       = "vt586b_smbus",
      .id_table   = vt586b_ids,
      .probe            = vt586b_probe,
      .remove           = __devexit_p(vt586b_remove),

static int __init i2c_vt586b_init(void)
      return pci_register_driver(&vt586b_driver);

static void __exit i2c_vt586b_exit(void)

MODULE_AUTHOR("Kyösti Mälkki <kmalkki@cc.hut.fi>");
MODULE_DESCRIPTION("i2c for Via vt82c586b southbridge");


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