drivers/i2c/i2c-boardinfo.c

   1 /*
   2  * i2c-boardinfo.c - collect pre-declarations of I2C devices
   3  *
   4  * This program is free software; you can redistribute it and/or modify
   5  * it under the terms of the GNU General Public License as published by
   6  * the Free Software Foundation; either version 2 of the License, or
   7  * (at your option) any later version.
   8  *
   9  * This program is distributed in the hope that it will be useful,
  10  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12  * GNU General Public License for more details.
  13  */
  14
  15 #include <linux/export.h>
  16 #include <linux/i2c.h>
  17 #include <linux/kernel.h>
  18 #include <linux/property.h>
  19 #include <linux/rwsem.h>
  20 #include <linux/slab.h>
  21
  22 #include "i2c-core.h"
  23
  24
  25 /* These symbols are exported ONLY FOR the i2c core.
  26  * No other users will be supported.
  27  */
  28 DECLARE_RWSEM(__i2c_board_lock);
  29 EXPORT_SYMBOL_GPL(__i2c_board_lock);
  30
  31 LIST_HEAD(__i2c_board_list);
  32 EXPORT_SYMBOL_GPL(__i2c_board_list);
  33
  34 int __i2c_first_dynamic_bus_num;
  35 EXPORT_SYMBOL_GPL(__i2c_first_dynamic_bus_num);
  36
  37
  38 /**
  39  * i2c_register_board_info - statically declare I2C devices
  40  * @busnum: identifies the bus to which these devices belong
  41  * @info: vector of i2c device descriptors
  42  * @len: how many descriptors in the vector; may be zero to reserve
  43  *      the specified bus number.
  44  *
  45  * Systems using the Linux I2C driver stack can declare tables of board info
  46  * while they initialize.  This should be done in board-specific init code
  47  * near arch_initcall() time, or equivalent, before any I2C adapter driver is
  48  * registered.  For example, mainboard init code could define several devices,
  49  * as could the init code for each daughtercard in a board stack.
  50  *
  51  * The I2C devices will be created later, after the adapter for the relevant
  52  * bus has been registered.  After that moment, standard driver model tools
  53  * are used to bind "new style" I2C drivers to the devices.  The bus number
  54  * for any device declared using this routine is not available for dynamic
  55  * allocation.
  56  *
  57  * The board info passed can safely be __initdata, but be careful of embedded
  58  * pointers (for platform_data, functions, etc) since that won't be copied.
  59  * Device properties are deep-copied though.
  60  */
  61 int i2c_register_board_info(int busnum, struct i2c_board_info const *info, unsigned len)
  62 {
  63         int status;
  64
  65         down_write(&__i2c_board_lock);
  66
  67         /* dynamic bus numbers will be assigned after the last static one */
  68         if (busnum >= __i2c_first_dynamic_bus_num)
  69                 __i2c_first_dynamic_bus_num = busnum + 1;
  70
  71         for (status = 0; len; len--, info++) {
  72                 struct i2c_devinfo      *devinfo;
  73
  74                 devinfo = kzalloc(sizeof(*devinfo), GFP_KERNEL);
  75                 if (!devinfo) {
  76                         pr_debug("i2c-core: can't register boardinfo!\n");
  77                         status = -ENOMEM;
  78                         break;
  79                 }
  80
  81                 devinfo->busnum = busnum;
  82                 devinfo->board_info = *info;
  83
  84                 if (info->properties) {
  85                         devinfo->board_info.properties =
  86                                         property_entries_dup(info->properties);
  87                         if (IS_ERR(devinfo->board_info.properties)) {
  88                                 status = PTR_ERR(devinfo->board_info.properties);
  89                                 kfree(devinfo);
  90                                 break;
  91                         }
  92                 }
  93
  94                 if (info->resources) {
  95                         devinfo->board_info.resources =
  96                                 kmemdup(info->resources,
  97                                         info->num_resources *
  98                                                 sizeof(*info->resources),
  99                                         GFP_KERNEL);
 100                         if (!devinfo->board_info.resources) {
 101                                 status = -ENOMEM;
 102                                 kfree(devinfo);
 103                                 break;
 104                         }
 105                 }
 106
 107                 list_add_tail(&devinfo->list, &__i2c_board_list);
 108         }
 109
 110         up_write(&__i2c_board_lock);
 111
 112         return status;
 113 }