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 };
  25
  26 static int of_find_i2c_driver(struct device_node *node,
  27                               struct i2c_board_info *info)
  28 {
  29         int i, cplen;
  30         const char *compatible;
  31         const char *p;
  32
  33         /* 1. search for exception list entry */
  34         for (i = 0; i < ARRAY_SIZE(i2c_devices); i++) {
  35                 if (!of_device_is_compatible(node, i2c_devices[i].of_device))
  36                         continue;
  37                 if (strlcpy(info->type, i2c_devices[i].i2c_type,
  38                             I2C_NAME_SIZE) >= I2C_NAME_SIZE)
  39                         return -ENOMEM;
  40
  41                 return 0;
  42         }
  43
  44         compatible = of_get_property(node, "compatible", &cplen);
  45         if (!compatible)
  46                 return -ENODEV;
  47
  48         /* 2. search for linux,<i2c-type> entry */
  49         p = compatible;
  50         while (cplen > 0) {
  51                 if (!strncmp(p, "linux,", 6)) {
  52                         p += 6;
  53                         if (strlcpy(info->type, p,
  54                                     I2C_NAME_SIZE) >= I2C_NAME_SIZE)
  55                                 return -ENOMEM;
  56                         return 0;
  57                 }
  58
  59                 i = strlen(p) + 1;
  60                 p += i;
  61                 cplen -= i;
  62         }
  63
  64         /* 3. take fist compatible entry and strip manufacturer */
  65         p = strchr(compatible, ',');
  66         if (!p)
  67                 return -ENODEV;
  68         p++;
  69         if (strlcpy(info->type, p, I2C_NAME_SIZE) >= I2C_NAME_SIZE)
  70                 return -ENOMEM;
  71         return 0;
  72 }
  73
  74 void of_register_i2c_devices(struct i2c_adapter *adap,
  75                              struct device_node *adap_node)
  76 {
  77         void *result;
  78         struct device_node *node;
  79
  80         for_each_child_of_node(adap_node, node) {
  81                 struct i2c_board_info info = {};
  82                 const u32 *addr;
  83                 int len;
  84
  85                 addr = of_get_property(node, "reg", &len);
  86                 if (!addr || len < sizeof(int) || *addr > (1 << 10) - 1) {
  87                         printk(KERN_ERR
  88                                "of-i2c: invalid i2c device entry\n");
  89                         continue;
  90                 }
  91
  92                 info.irq = irq_of_parse_and_map(node, 0);
  93                 if (info.irq == NO_IRQ)
  94                         info.irq = -1;
  95
  96                 if (of_find_i2c_driver(node, &info) < 0) {
  97                         irq_dispose_mapping(info.irq);
  98                         continue;
  99                 }
 100
 101                 info.addr = *addr;
 102
 103                 request_module(info.type);
 104
 105                 result = i2c_new_device(adap, &info);
 106                 if (result == NULL) {
 107                         printk(KERN_ERR
 108                                "of-i2c: Failed to load driver for %s\n",
 109                                info.type);
 110                         irq_dispose_mapping(info.irq);
 111                         continue;
 112                 }
 113         }
 114 }
 115 EXPORT_SYMBOL(of_register_i2c_devices);
 116
 117 MODULE_LICENSE("GPL");