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  */
i2c_register_board_info(int busnum,struct i2c_board_info const * info,unsigned len)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 }
94