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  * Device properties are deep-copied though.
  51  */
  52 int i2c_register_board_info(int busnum, struct i2c_board_info const *info, unsigned len)
  53 {
  54         int status;
  55
  56         down_write(&__i2c_board_lock);
  57
  58         /* dynamic bus numbers will be assigned after the last static one */
  59         if (busnum >= __i2c_first_dynamic_bus_num)
  60                 __i2c_first_dynamic_bus_num = busnum + 1;
  61
  62         for (status = 0; len; len--, info++) {
  63                 struct i2c_devinfo      *devinfo;
  64
  65                 devinfo = kzalloc(sizeof(*devinfo), GFP_KERNEL);
  66                 if (!devinfo) {
  67                         pr_debug("i2c-core: can't register boardinfo!\n");
  68                         status = -ENOMEM;
  69                         break;
  70                 }
  71
  72                 devinfo->busnum = busnum;
  73                 devinfo->board_info = *info;
  74
  75                 if (info->properties) {
  76                         devinfo->board_info.properties =
  77                                         property_entries_dup(info->properties);
  78                         if (IS_ERR(devinfo->board_info.properties)) {
  79                                 status = PTR_ERR(devinfo->board_info.properties);
  80                                 kfree(devinfo);
  81                                 break;
  82                         }
  83                 }
  84
  85                 if (info->resources) {
  86                         devinfo->board_info.resources =
  87                                 kmemdup(info->resources,
  88                                         info->num_resources *
  89                                                 sizeof(*info->resources),
  90                                         GFP_KERNEL);
  91                         if (!devinfo->board_info.resources) {
  92                                 status = -ENOMEM;
  93                                 kfree(devinfo);
  94                                 break;
  95                         }
  96                 }
  97
  98                 list_add_tail(&devinfo->list, &__i2c_board_list);
  99         }
 100
 101         up_write(&__i2c_board_lock);
 102
 103         return status;
 104 }