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  * 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  */
  32 DECLARE_RWSEM(__i2c_board_lock);
  33 EXPORT_SYMBOL_GPL(__i2c_board_lock);
  34
  35 LIST_HEAD(__i2c_board_list);
  36 EXPORT_SYMBOL_GPL(__i2c_board_list);
  37
  38 int __i2c_first_dynamic_bus_num;
  39 EXPORT_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  */
  64 int __init
  65 i2c_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 }