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(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(size: 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(p: info->resources, |
77 | size: 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 | |