drivers/i2c/i2c-boardinfo.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   3  * i2c-boardinfo.c - collect pre-declarations of I2C devices
   4  */
   5
   6 #include <linux/export.h>
   7 #include <linux/i2c.h>
   8 #include <linux/kernel.h>
   9 #include <linux/property.h>
  10 #include <linux/rwsem.h>
  11 #include <linux/slab.h>
  12
  13 #include "i2c-core.h"
  14
  15
  16 /* These symbols are exported ONLY FOR the i2c core.
  17  * No other users will be supported.
  18  */
  19 DECLARE_RWSEM(__i2c_board_lock);
  20 EXPORT_SYMBOL_GPL(__i2c_board_lock);
  21
  22 LIST_HEAD(__i2c_board_list);
  23 EXPORT_SYMBOL_GPL(__i2c_board_list);
  24
  25 int __i2c_first_dynamic_bus_num;
  26 EXPORT_SYMBOL_GPL(__i2c_first_dynamic_bus_num);
  27
  28
  29 /**
  30  * i2c_register_board_info - statically declare I2C devices
  31  * @busnum: identifies the bus to which these devices belong
  32  * @info: vector of i2c device descriptors
  33  * @len: how many descriptors in the vector; may be zero to reserve
  34  *      the specified bus number.
  35  *
  36  * Systems using the Linux I2C driver stack can declare tables of board info
  37  * while they initialize.  This should be done in board-specific init code
  38  * near arch_initcall() time, or equivalent, before any I2C adapter driver is
  39  * registered.  For example, mainboard init code could define several devices,
  40  * as could the init code for each daughtercard in a board stack.
  41  *
  42  * The I2C devices will be created later, after the adapter for the relevant
  43  * bus has been registered.  After that moment, standard driver model tools
  44  * are used to bind "new style" I2C drivers to the devices.  The bus number
  45  * for any device declared using this routine is not available for dynamic
  46  * allocation.
  47  *
  48  * The board info passed can safely be __initdata, but be careful of embedded
  49  * pointers (for platform_data, functions, etc) since that won't be copied.
  50  */
  51 int i2c_register_board_info(int busnum, struct i2c_board_info const *info, unsigned len)
  52 {
  53         int status;
  54
  55         down_write(&__i2c_board_lock);
  56
  57         /* dynamic bus numbers will be assigned after the last static one */
  58         if (busnum >= __i2c_first_dynamic_bus_num)
  59                 __i2c_first_dynamic_bus_num = busnum + 1;
  60
  61         for (status = 0; len; len--, info++) {
  62                 struct i2c_devinfo      *devinfo;
  63
  64                 devinfo = kzalloc(sizeof(*devinfo), GFP_KERNEL);
  65                 if (!devinfo) {
  66                         pr_debug("i2c-core: can't register boardinfo!\n");
  67                         status = -ENOMEM;
  68                         break;
  69                 }
  70
  71                 devinfo->busnum = busnum;
  72                 devinfo->board_info = *info;
  73
  74                 if (info->resources) {
  75                         devinfo->board_info.resources =
  76                                 kmemdup(info->resources,
  77                                         info->num_resources *
  78                                                 sizeof(*info->resources),
  79                                         GFP_KERNEL);
  80                         if (!devinfo->board_info.resources) {
  81                                 status = -ENOMEM;
  82                                 kfree(devinfo);
  83                                 break;
  84                         }
  85                 }
  86
  87                 list_add_tail(&devinfo->list, &__i2c_board_list);
  88         }
  89
  90         up_write(&__i2c_board_lock);
  91
  92         return status;
  93 }