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