linux/drivers/i2c/i2c-boardinfo.c
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   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., 51 Franklin Street, Fifth Floor, Boston,
  17 * MA 02110-1301 USA.
  18 */
  19
  20#include <linux/kernel.h>
  21#include <linux/i2c.h>
  22#include <linux/slab.h>
  23#include <linux/export.h>
  24#include <linux/rwsem.h>
  25
  26#include "i2c-core.h"
  27
  28
  29/* These symbols are exported ONLY FOR the i2c core.
  30 * No other users will be supported.
  31 */
  32DECLARE_RWSEM(__i2c_board_lock);
  33EXPORT_SYMBOL_GPL(__i2c_board_lock);
  34
  35LIST_HEAD(__i2c_board_list);
  36EXPORT_SYMBOL_GPL(__i2c_board_list);
  37
  38int __i2c_first_dynamic_bus_num;
  39EXPORT_SYMBOL_GPL(__i2c_first_dynamic_bus_num);
  40
  41
  42/**
  43 * i2c_register_board_info - statically declare I2C devices
  44 * @busnum: identifies the bus to which these devices belong
  45 * @info: vector of i2c device descriptors
  46 * @len: how many descriptors in the vector; may be zero to reserve
  47 *      the specified bus number.
  48 *
  49 * Systems using the Linux I2C driver stack can declare tables of board info
  50 * while they initialize.  This should be done in board-specific init code
  51 * near arch_initcall() time, or equivalent, before any I2C adapter driver is
  52 * registered.  For example, mainboard init code could define several devices,
  53 * as could the init code for each daughtercard in a board stack.
  54 *
  55 * The I2C devices will be created later, after the adapter for the relevant
  56 * bus has been registered.  After that moment, standard driver model tools
  57 * are used to bind "new style" I2C drivers to the devices.  The bus number
  58 * for any device declared using this routine is not available for dynamic
  59 * allocation.
  60 *
  61 * The board info passed can safely be __initdata, but be careful of embedded
  62 * pointers (for platform_data, functions, etc) since that won't be copied.
  63 */
  64int __init
  65i2c_register_board_info(int busnum,
  66        struct i2c_board_info const *info, unsigned len)
  67{
  68        int status;
  69
  70        down_write(&__i2c_board_lock);
  71
  72        /* dynamic bus numbers will be assigned after the last static one */
  73        if (busnum >= __i2c_first_dynamic_bus_num)
  74                __i2c_first_dynamic_bus_num = busnum + 1;
  75
  76        for (status = 0; len; len--, info++) {
  77                struct i2c_devinfo      *devinfo;
  78
  79                devinfo = kzalloc(sizeof(*devinfo), GFP_KERNEL);
  80                if (!devinfo) {
  81                        pr_debug("i2c-core: can't register boardinfo!\n");
  82                        status = -ENOMEM;
  83                        break;
  84                }
  85
  86                devinfo->busnum = busnum;
  87                devinfo->board_info = *info;
  88                list_add_tail(&devinfo->list, &__i2c_board_list);
  89        }
  90
  91        up_write(&__i2c_board_lock);
  92
  93        return status;
  94}
  95
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