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/kernel.h>
  16 #include <linux/i2c.h>
  17 #include <linux/slab.h>
  18 #include <linux/export.h>
  19 #include <linux/rwsem.h>
  20
  21 #include "i2c-core.h"
  22
  23
  24 /* These symbols are exported ONLY FOR the i2c core.
  25  * No other users will be supported.
  26  */
  27 DECLARE_RWSEM(__i2c_board_lock);
  28 EXPORT_SYMBOL_GPL(__i2c_board_lock);
  29
  30 LIST_HEAD(__i2c_board_list);
  31 EXPORT_SYMBOL_GPL(__i2c_board_list);
  32
  33 int __i2c_first_dynamic_bus_num;
  34 EXPORT_SYMBOL_GPL(__i2c_first_dynamic_bus_num);
  35
  36
  37 /**
  38  * i2c_register_board_info - statically declare I2C devices
  39  * @busnum: identifies the bus to which these devices belong
  40  * @info: vector of i2c device descriptors
  41  * @len: how many descriptors in the vector; may be zero to reserve
  42  *      the specified bus number.
  43  *
  44  * Systems using the Linux I2C driver stack can declare tables of board info
  45  * while they initialize.  This should be done in board-specific init code
  46  * near arch_initcall() time, or equivalent, before any I2C adapter driver is
  47  * registered.  For example, mainboard init code could define several devices,
  48  * as could the init code for each daughtercard in a board stack.
  49  *
  50  * The I2C devices will be created later, after the adapter for the relevant
  51  * bus has been registered.  After that moment, standard driver model tools
  52  * are used to bind "new style" I2C drivers to the devices.  The bus number
  53  * for any device declared using this routine is not available for dynamic
  54  * allocation.
  55  *
  56  * The board info passed can safely be __initdata, but be careful of embedded
  57  * pointers (for platform_data, functions, etc) since that won't be copied.
  58  */
  59 int __init
  60 i2c_register_board_info(int busnum,
  61         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                 list_add_tail(&devinfo->list, &__i2c_board_list);
  84         }
  85
  86         up_write(&__i2c_board_lock);
  87
  88         return status;
  89 }