drivers/i2c/busses/i2c-via.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   3     i2c Support for Via Technologies 82C586B South Bridge
   4
   5     Copyright (c) 1998, 1999 Kyösti Mälkki <kmalkki@cc.hut.fi>
   6
   7 */
   8
   9 #include <linux/kernel.h>
  10 #include <linux/module.h>
  11 #include <linux/pci.h>
  12 #include <linux/ioport.h>
  13 #include <linux/i2c.h>
  14 #include <linux/i2c-algo-bit.h>
  15 #include <linux/io.h>
  16
  17 /* Power management registers */
  18 #define PM_CFG_REVID    0x08    /* silicon revision code */
  19 #define PM_CFG_IOBASE0  0x20
  20 #define PM_CFG_IOBASE1  0x48
  21
  22 #define I2C_DIR         (pm_io_base+0x40)
  23 #define I2C_OUT         (pm_io_base+0x42)
  24 #define I2C_IN          (pm_io_base+0x44)
  25 #define I2C_SCL         0x02    /* clock bit in DIR/OUT/IN register */
  26 #define I2C_SDA         0x04
  27
  28 /* io-region reservation */
  29 #define IOSPACE         0x06
  30
  31 static struct pci_driver vt586b_driver;
  32 static u16 pm_io_base;
  33
  34 /*
  35    It does not appear from the datasheet that the GPIO pins are
  36    open drain. So a we set a low value by setting the direction to
  37    output and a high value by setting the direction to input and
  38    relying on the required I2C pullup. The data value is initialized
  39    to 0 in via_init() and never changed.
  40 */
  41 static void bit_via_setscl(void *data, int state)
  42 {
  43         outb(state ? inb(I2C_DIR) & ~I2C_SCL : inb(I2C_DIR) | I2C_SCL, I2C_DIR);
  44 }
  45
  46 static void bit_via_setsda(void *data, int state)
  47 {
  48         outb(state ? inb(I2C_DIR) & ~I2C_SDA : inb(I2C_DIR) | I2C_SDA, I2C_DIR);
  49 }
  50
  51 static int bit_via_getscl(void *data)
  52 {
  53         return (0 != (inb(I2C_IN) & I2C_SCL));
  54 }
  55
  56 static int bit_via_getsda(void *data)
  57 {
  58         return (0 != (inb(I2C_IN) & I2C_SDA));
  59 }
  60
  61
  62 static struct i2c_algo_bit_data bit_data = {
  63         .setsda         = bit_via_setsda,
  64         .setscl         = bit_via_setscl,
  65         .getsda         = bit_via_getsda,
  66         .getscl         = bit_via_getscl,
  67         .udelay         = 5,
  68         .timeout        = HZ
  69 };
  70
  71 static struct i2c_adapter vt586b_adapter = {
  72         .owner          = THIS_MODULE,
  73         .class          = I2C_CLASS_HWMON,
  74         .name           = "VIA i2c",
  75         .algo_data      = &bit_data,
  76 };
  77
  78
  79 static const struct pci_device_id vt586b_ids[] = {
  80         { PCI_DEVICE(PCI_VENDOR_ID_VIA, PCI_DEVICE_ID_VIA_82C586_3) },
  81         { 0, }
  82 };
  83
  84 MODULE_DEVICE_TABLE (pci, vt586b_ids);
  85
  86 static int vt586b_probe(struct pci_dev *dev, const struct pci_device_id *id)
  87 {
  88         u16 base;
  89         u8 rev;
  90         int res;
  91
  92         if (pm_io_base) {
  93                 dev_err(&dev->dev, "i2c-via: Will only support one host\n");
  94                 return -ENODEV;
  95         }
  96
  97         pci_read_config_byte(dev, PM_CFG_REVID, &rev);
  98
  99         switch (rev) {
 100         case 0x00:
 101                 base = PM_CFG_IOBASE0;
 102                 break;
 103         case 0x01:
 104         case 0x10:
 105                 base = PM_CFG_IOBASE1;
 106                 break;
 107
 108         default:
 109                 base = PM_CFG_IOBASE1;
 110                 /* later revision */
 111         }
 112
 113         pci_read_config_word(dev, base, &pm_io_base);
 114         pm_io_base &= (0xff << 8);
 115
 116         if (!request_region(I2C_DIR, IOSPACE, vt586b_driver.name)) {
 117                 dev_err(&dev->dev, "IO 0x%x-0x%x already in use\n", I2C_DIR, I2C_DIR + IOSPACE);
 118                 return -ENODEV;
 119         }
 120
 121         outb(inb(I2C_DIR) & ~(I2C_SDA | I2C_SCL), I2C_DIR);
 122         outb(inb(I2C_OUT) & ~(I2C_SDA | I2C_SCL), I2C_OUT);
 123
 124         /* set up the sysfs linkage to our parent device */
 125         vt586b_adapter.dev.parent = &dev->dev;
 126
 127         res = i2c_bit_add_bus(&vt586b_adapter);
 128         if ( res < 0 ) {
 129                 release_region(I2C_DIR, IOSPACE);
 130                 pm_io_base = 0;
 131                 return res;
 132         }
 133         return 0;
 134 }
 135
 136 static void vt586b_remove(struct pci_dev *dev)
 137 {
 138         i2c_del_adapter(&vt586b_adapter);
 139         release_region(I2C_DIR, IOSPACE);
 140         pm_io_base = 0;
 141 }
 142
 143
 144 static struct pci_driver vt586b_driver = {
 145         .name           = "vt586b_smbus",
 146         .id_table       = vt586b_ids,
 147         .probe          = vt586b_probe,
 148         .remove         = vt586b_remove,
 149 };
 150
 151 module_pci_driver(vt586b_driver);
 152
 153 MODULE_AUTHOR("Kyösti Mälkki <kmalkki@cc.hut.fi>");
 154 MODULE_DESCRIPTION("i2c for Via vt82c586b southbridge");
 155 MODULE_LICENSE("GPL");