linux/drivers/i2c/i2c-boardinfo.c
<<
>>
Prefs
   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 * You should have received a copy of the GNU General Public License
  15 * along with this program; if not, write to the Free Software
  16 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
  17 */
  18
  19#include <linux/kernel.h>
  20#include <linux/i2c.h>
  21#include <linux/slab.h>
  22#include <linux/rwsem.h>
  23
  24#include "i2c-core.h"
  25
  26
  27/* These symbols are exported ONLY FOR the i2c core.
  28 * No other users will be supported.
  29 */
  30DECLARE_RWSEM(__i2c_board_lock);
  31EXPORT_SYMBOL_GPL(__i2c_board_lock);
  32
  33LIST_HEAD(__i2c_board_list);
  34EXPORT_SYMBOL_GPL(__i2c_board_list);
  35
  36int __i2c_first_dynamic_bus_num;
  37EXPORT_SYMBOL_GPL(__i2c_first_dynamic_bus_num);
  38
  39
  40/**
  41 * i2c_register_board_info - statically declare I2C devices
  42 * @busnum: identifies the bus to which these devices belong
  43 * @info: vector of i2c device descriptors
  44 * @len: how many descriptors in the vector; may be zero to reserve
  45 *      the specified bus number.
  46 *
  47 * Systems using the Linux I2C driver stack can declare tables of board info
  48 * while they initialize.  This should be done in board-specific init code
  49 * near arch_initcall() time, or equivalent, before any I2C adapter driver is
  50 * registered.  For example, mainboard init code could define several devices,
  51 * as could the init code for each daughtercard in a board stack.
  52 *
  53 * The I2C devices will be created later, after the adapter for the relevant
  54 * bus has been registered.  After that moment, standard driver model tools
  55 * are used to bind "new style" I2C drivers to the devices.  The bus number
  56 * for any device declared using this routine is not available for dynamic
  57 * allocation.
  58 *
  59 * The board info passed can safely be __initdata, but be careful of embedded
  60 * pointers (for platform_data, functions, etc) since that won't be copied.
  61 */
  62int __init
  63i2c_register_board_info(int busnum,
  64        struct i2c_board_info const *info, unsigned len)
  65{
  66        int status;
  67
  68        down_write(&__i2c_board_lock);
  69
  70        /* dynamic bus numbers will be assigned after the last static one */
  71        if (busnum >= __i2c_first_dynamic_bus_num)
  72                __i2c_first_dynamic_bus_num = busnum + 1;
  73
  74        for (status = 0; len; len--, info++) {
  75                struct i2c_devinfo      *devinfo;
  76
  77                devinfo = kzalloc(sizeof(*devinfo), GFP_KERNEL);
  78                if (!devinfo) {
  79                        pr_debug("i2c-core: can't register boardinfo!\n");
  80                        status = -ENOMEM;
  81                        break;
  82                }
  83
  84                devinfo->busnum = busnum;
  85                devinfo->board_info = *info;
  86                list_add_tail(&devinfo->list, &__i2c_board_list);
  87        }
  88
  89        up_write(&__i2c_board_lock);
  90
  91        return status;
  92}
  93