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