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 */
19DECLARE_RWSEM(__i2c_board_lock);
20EXPORT_SYMBOL_GPL(__i2c_board_lock);
21
22LIST_HEAD(__i2c_board_list);
23EXPORT_SYMBOL_GPL(__i2c_board_list);
24
25int __i2c_first_dynamic_bus_num __ro_after_init;
26EXPORT_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 */
51int __init i2c_register_board_info(int busnum, struct i2c_board_info const *info, unsigned len)
52{
53 int status;
54
55 down_write(sem: &__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(objp: devinfo);
83 break;
84 }
85 }
86
87 list_add_tail(new: &devinfo->list, head: &__i2c_board_list);
88 }
89
90 up_write(sem: &__i2c_board_lock);
91
92 return status;
93}
94