drivers/i2c/i2c-boardinfo.c

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