drivers/i2c/busses/i2c-via.c

   1 /*
   2     i2c Support for Via Technologies 82C586B South Bridge
   3
   4     Copyright (c) 1998, 1999 Kyösti Mälkki <kmalkki@cc.hut.fi>
   5
   6     This program is free software; you can redistribute it and/or modify
   7     it under the terms of the GNU General Public License as published by
   8     the Free Software Foundation; either version 2 of the License, or
   9     (at your option) any later version.
  10
  11     This program is distributed in the hope that it will be useful,
  12     but WITHOUT ANY WARRANTY; without even the implied warranty of
  13     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14     GNU General Public License for more details.
  15 */
  16
  17 #include <linux/kernel.h>
  18 #include <linux/module.h>
  19 #include <linux/pci.h>
  20 #include <linux/ioport.h>
  21 #include <linux/i2c.h>
  22 #include <linux/i2c-algo-bit.h>
  23 #include <linux/io.h>
  24
  25 /* Power management registers */
  26 #define PM_CFG_REVID    0x08    /* silicon revision code */
  27 #define PM_CFG_IOBASE0  0x20
  28 #define PM_CFG_IOBASE1  0x48
  29
  30 #define I2C_DIR         (pm_io_base+0x40)
  31 #define I2C_OUT         (pm_io_base+0x42)
  32 #define I2C_IN          (pm_io_base+0x44)
  33 #define I2C_SCL         0x02    /* clock bit in DIR/OUT/IN register */
  34 #define I2C_SDA         0x04
  35
  36 /* io-region reservation */
  37 #define IOSPACE         0x06
  38
  39 static struct pci_driver vt586b_driver;
  40 static u16 pm_io_base;
  41
  42 /*
  43    It does not appear from the datasheet that the GPIO pins are
  44    open drain. So a we set a low value by setting the direction to
  45    output and a high value by setting the direction to input and
  46    relying on the required I2C pullup. The data value is initialized
  47    to 0 in via_init() and never changed.
  48 */
  49 static void bit_via_setscl(void *data, int state)
  50 {
  51         outb(state ? inb(I2C_DIR) & ~I2C_SCL : inb(I2C_DIR) | I2C_SCL, I2C_DIR);
  52 }
  53
  54 static void bit_via_setsda(void *data, int state)
  55 {
  56         outb(state ? inb(I2C_DIR) & ~I2C_SDA : inb(I2C_DIR) | I2C_SDA, I2C_DIR);
  57 }
  58
  59 static int bit_via_getscl(void *data)
  60 {
  61         return (0 != (inb(I2C_IN) & I2C_SCL));
  62 }
  63
  64 static int bit_via_getsda(void *data)
  65 {
  66         return (0 != (inb(I2C_IN) & I2C_SDA));
  67 }
  68
  69
  70 static struct i2c_algo_bit_data bit_data = {
  71         .setsda         = bit_via_setsda,
  72         .setscl         = bit_via_setscl,
  73         .getsda         = bit_via_getsda,
  74         .getscl         = bit_via_getscl,
  75         .udelay         = 5,
  76         .timeout        = HZ
  77 };
  78
  79 static struct i2c_adapter vt586b_adapter = {
  80         .owner          = THIS_MODULE,
  81         .class          = I2C_CLASS_HWMON | I2C_CLASS_SPD,
  82         .name           = "VIA i2c",
  83         .algo_data      = &bit_data,
  84 };
  85
  86
  87 static const struct pci_device_id vt586b_ids[] = {
  88         { PCI_DEVICE(PCI_VENDOR_ID_VIA, PCI_DEVICE_ID_VIA_82C586_3) },
  89         { 0, }
  90 };
  91
  92 MODULE_DEVICE_TABLE (pci, vt586b_ids);
  93
  94 static int vt586b_probe(struct pci_dev *dev, const struct pci_device_id *id)
  95 {
  96         u16 base;
  97         u8 rev;
  98         int res;
  99
 100         if (pm_io_base) {
 101                 dev_err(&dev->dev, "i2c-via: Will only support one host\n");
 102                 return -ENODEV;
 103         }
 104
 105         pci_read_config_byte(dev, PM_CFG_REVID, &rev);
 106
 107         switch (rev) {
 108         case 0x00:
 109                 base = PM_CFG_IOBASE0;
 110                 break;
 111         case 0x01:
 112         case 0x10:
 113                 base = PM_CFG_IOBASE1;
 114                 break;
 115
 116         default:
 117                 base = PM_CFG_IOBASE1;
 118                 /* later revision */
 119         }
 120
 121         pci_read_config_word(dev, base, &pm_io_base);
 122         pm_io_base &= (0xff << 8);
 123
 124         if (!request_region(I2C_DIR, IOSPACE, vt586b_driver.name)) {
 125                 dev_err(&dev->dev, "IO 0x%x-0x%x already in use\n", I2C_DIR, I2C_DIR + IOSPACE);
 126                 return -ENODEV;
 127         }
 128
 129         outb(inb(I2C_DIR) & ~(I2C_SDA | I2C_SCL), I2C_DIR);
 130         outb(inb(I2C_OUT) & ~(I2C_SDA | I2C_SCL), I2C_OUT);
 131
 132         /* set up the sysfs linkage to our parent device */
 133         vt586b_adapter.dev.parent = &dev->dev;
 134
 135         res = i2c_bit_add_bus(&vt586b_adapter);
 136         if ( res < 0 ) {
 137                 release_region(I2C_DIR, IOSPACE);
 138                 pm_io_base = 0;
 139                 return res;
 140         }
 141         return 0;
 142 }
 143
 144 static void vt586b_remove(struct pci_dev *dev)
 145 {
 146         i2c_del_adapter(&vt586b_adapter);
 147         release_region(I2C_DIR, IOSPACE);
 148         pm_io_base = 0;
 149 }
 150
 151
 152 static struct pci_driver vt586b_driver = {
 153         .name           = "vt586b_smbus",
 154         .id_table       = vt586b_ids,
 155         .probe          = vt586b_probe,
 156         .remove         = vt586b_remove,
 157 };
 158
 159 module_pci_driver(vt586b_driver);
 160
 161 MODULE_AUTHOR("Kyösti Mälkki <kmalkki@cc.hut.fi>");
 162 MODULE_DESCRIPTION("i2c for Via vt82c586b southbridge");
 163 MODULE_LICENSE("GPL");