LXR linux/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 */
  27DECLARE_RWSEM(__i2c_board_lock);
  28EXPORT_SYMBOL_GPL(__i2c_board_lock);
  29
  30LIST_HEAD(__i2c_board_list);
  31EXPORT_SYMBOL_GPL(__i2c_board_list);
  32
  33int __i2c_first_dynamic_bus_num;
  34EXPORT_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 */
  59int __init
  60i2c_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}
  90