drivers/of/of_i2c.c

   1 /*
   2  * OF helpers for the I2C API
   3  *
   4  * Copyright (c) 2008 Jochen Friedrich <jochen@scram.de>
   5  *
   6  * Based on a previous patch from Jon Smirl <jonsmirl@gmail.com>
   7  *
   8  * This program is free software; you can redistribute it and/or modify
   9  * it under the terms of the GNU General Public License as published by
  10  * the Free Software Foundation; either version 2 of the License, or
  11  * (at your option) any later version.
  12  */
  13
  14 #include <linux/i2c.h>
  15 #include <linux/of.h>
  16 #include <linux/module.h>
  17
  18 struct i2c_driver_device {
  19         char    *of_device;
  20         char    *i2c_type;
  21 };
  22
  23 static struct i2c_driver_device i2c_devices[] = {
  24         { "dallas,ds1374", "rtc-ds1374" },
  25 };
  26
  27 static int of_find_i2c_driver(struct device_node *node,
  28                               struct i2c_board_info *info)
  29 {
  30         int i, cplen;
  31         const char *compatible;
  32         const char *p;
  33
  34         /* 1. search for exception list entry */
  35         for (i = 0; i < ARRAY_SIZE(i2c_devices); i++) {
  36                 if (!of_device_is_compatible(node, i2c_devices[i].of_device))
  37                         continue;
  38                 if (strlcpy(info->type, i2c_devices[i].i2c_type,
  39                             I2C_NAME_SIZE) >= I2C_NAME_SIZE)
  40                         return -ENOMEM;
  41
  42                 return 0;
  43         }
  44
  45         compatible = of_get_property(node, "compatible", &cplen);
  46         if (!compatible)
  47                 return -ENODEV;
  48
  49         /* 2. search for linux,<i2c-type> entry */
  50         p = compatible;
  51         while (cplen > 0) {
  52                 if (!strncmp(p, "linux,", 6)) {
  53                         p += 6;
  54                         if (strlcpy(info->type, p,
  55                                     I2C_NAME_SIZE) >= I2C_NAME_SIZE)
  56                                 return -ENOMEM;
  57                         return 0;
  58                 }
  59
  60                 i = strlen(p) + 1;
  61                 p += i;
  62                 cplen -= i;
  63         }
  64
  65         /* 3. take fist compatible entry and strip manufacturer */
  66         p = strchr(compatible, ',');
  67         if (!p)
  68                 return -ENODEV;
  69         p++;
  70         if (strlcpy(info->type, p, I2C_NAME_SIZE) >= I2C_NAME_SIZE)
  71                 return -ENOMEM;
  72         return 0;
  73 }
  74
  75 void of_register_i2c_devices(struct i2c_adapter *adap,
  76                              struct device_node *adap_node)
  77 {
  78         void *result;
  79         struct device_node *node;
  80
  81         for_each_child_of_node(adap_node, node) {
  82                 struct i2c_board_info info = {};
  83                 const u32 *addr;
  84                 int len;
  85
  86                 addr = of_get_property(node, "reg", &len);
  87                 if (!addr || len < sizeof(int) || *addr > (1 << 10) - 1) {
  88                         printk(KERN_ERR
  89                                "of-i2c: invalid i2c device entry\n");
  90                         continue;
  91                 }
  92
  93                 info.irq = irq_of_parse_and_map(node, 0);
  94                 if (info.irq == NO_IRQ)
  95                         info.irq = -1;
  96
  97                 if (of_find_i2c_driver(node, &info) < 0) {
  98                         irq_dispose_mapping(info.irq);
  99                         continue;
 100                 }
 101
 102                 info.addr = *addr;
 103
 104                 request_module(info.type);
 105
 106                 result = i2c_new_device(adap, &info);
 107                 if (result == NULL) {
 108                         printk(KERN_ERR
 109                                "of-i2c: Failed to load driver for %s\n",
 110                                info.type);
 111                         irq_dispose_mapping(info.irq);
 112                         continue;
 113                 }
 114         }
 115 }
 116 EXPORT_SYMBOL(of_register_i2c_devices);
 117
 118 MODULE_LICENSE("GPL");