1// SPDX-License-Identifier: GPL-2.0
 2/*
 3 * Linux kernel module helpers.
 4 */
 5
 6#include <linux/of.h>
 7#include <linux/module.h>
 8#include <linux/slab.h>
 9#include <linux/string.h>
10
11ssize_t of_modalias(const struct device_node *np, char *str, ssize_t len)
12{
13	const char *compat;
14	char *c;
15	struct property *p;
16	ssize_t csize;
17	ssize_t tsize;
18
19	/*
20	 * Prevent a kernel oops in vsnprintf() -- it only allows passing a
21	 * NULL ptr when the length is also 0. Also filter out the negative
22	 * lengths...
23	 */
24	if ((len > 0 && !str) || len < 0)
25		return -EINVAL;
26
27	/* Name & Type */
28	/* %p eats all alphanum characters, so %c must be used here */
29	csize = snprintf(str, len, "of:N%pOFn%c%s", np, 'T',
30			 of_node_get_device_type(np));
31	tsize = csize;
32	if (csize >= len)
33		csize = len > 0 ? len - 1 : 0;
34	len -= csize;
35	str += csize;
36
37	of_property_for_each_string(np, "compatible", p, compat) {
38		csize = snprintf(str, len, "C%s", compat);
39		tsize += csize;
40		if (csize >= len)
41			continue;
42		for (c = str; c; ) {
43			c = strchr(c, ' ');
44			if (c)
45				*c++ = '_';
46		}
47		len -= csize;
48		str += csize;
49	}
50
51	return tsize;
52}
53
54int of_request_module(const struct device_node *np)
55{
56	char *str;
57	ssize_t size;
58	int ret;
59
60	if (!np)
61		return -ENODEV;
62
63	size = of_modalias(np, NULL, 0);
64	if (size < 0)
65		return size;
66
67	/* Reserve an additional byte for the trailing '\0' */
68	size++;
69
70	str = kmalloc(size, GFP_KERNEL);
71	if (!str)
72		return -ENOMEM;
73
74	of_modalias(np, str, size);
75	str[size - 1] = '\0';
76	ret = request_module(str);
77	kfree(str);
78
79	return ret;
80}
81EXPORT_SYMBOL_GPL(of_request_module);