1// SPDX-License-Identifier: LGPL-2.1+
 2/*
 3 * Copyright (C) 2003 David Brownell
 
 
 
 
 
 4 */
 5
 6#include <linux/errno.h>
 7#include <linux/kernel.h>
 8#include <linux/module.h>
 9#include <linux/list.h>
10#include <linux/string.h>
11#include <linux/device.h>
12#include <linux/nls.h>
13
14#include <linux/usb/ch9.h>
15#include <linux/usb/gadget.h>
16
17
18/**
19 * usb_gadget_get_string - fill out a string descriptor 
20 * @table: of c strings encoded using UTF-8
21 * @id: string id, from low byte of wValue in get string descriptor
22 * @buf: at least 256 bytes, must be 16-bit aligned
23 *
24 * Finds the UTF-8 string matching the ID, and converts it into a
25 * string descriptor in utf16-le.
26 * Returns length of descriptor (always even) or negative errno
27 *
28 * If your driver needs stings in multiple languages, you'll probably
29 * "switch (wIndex) { ... }"  in your ep0 string descriptor logic,
30 * using this routine after choosing which set of UTF-8 strings to use.
31 * Note that US-ASCII is a strict subset of UTF-8; any string bytes with
32 * the eighth bit set will be multibyte UTF-8 characters, not ISO-8859/1
33 * characters (which are also widely used in C strings).
34 */
35int
36usb_gadget_get_string (const struct usb_gadget_strings *table, int id, u8 *buf)
37{
38	struct usb_string	*s;
39	int			len;
40
41	/* descriptor 0 has the language id */
42	if (id == 0) {
43		buf [0] = 4;
44		buf [1] = USB_DT_STRING;
45		buf [2] = (u8) table->language;
46		buf [3] = (u8) (table->language >> 8);
47		return 4;
48	}
49	for (s = table->strings; s && s->s; s++)
50		if (s->id == id)
51			break;
52
53	/* unrecognized: stall. */
54	if (!s || !s->s)
55		return -EINVAL;
56
57	/* string descriptors have length, tag, then UTF16-LE text */
58	len = min((size_t)USB_MAX_STRING_LEN, strlen(s->s));
59	len = utf8s_to_utf16s(s->s, len, UTF16_LITTLE_ENDIAN,
60			(wchar_t *) &buf[2], USB_MAX_STRING_LEN);
61	if (len < 0)
62		return -EINVAL;
63	buf [0] = (len + 1) * 2;
64	buf [1] = USB_DT_STRING;
65	return buf [0];
66}
67EXPORT_SYMBOL_GPL(usb_gadget_get_string);
68
69/**
70 * usb_validate_langid - validate usb language identifiers
71 * @langid: usb language identifier
72 *
73 * Returns true for valid language identifier, otherwise false.
74 */
75bool usb_validate_langid(u16 langid)
76{
77	u16 primary_lang = langid & 0x3ff;	/* bit [9:0] */
78	u16 sub_lang = langid >> 10;		/* bit [15:10] */
79
80	switch (primary_lang) {
81	case 0:
82	case 0x62 ... 0xfe:
83	case 0x100 ... 0x3ff:
84		return false;
85	}
86	if (!sub_lang)
87		return false;
88
89	return true;
90}
91EXPORT_SYMBOL_GPL(usb_validate_langid);

 
 1/*
 2 * Copyright (C) 2003 David Brownell
 3 *
 4 * This program is free software; you can redistribute it and/or modify
 5 * it under the terms of the GNU Lesser General Public License as published
 6 * by the Free Software Foundation; either version 2.1 of the License, or
 7 * (at your option) any later version.
 8 */
 9
10#include <linux/errno.h>
11#include <linux/kernel.h>
12#include <linux/module.h>
13#include <linux/list.h>
14#include <linux/string.h>
15#include <linux/device.h>
16#include <linux/nls.h>
17
18#include <linux/usb/ch9.h>
19#include <linux/usb/gadget.h>
20
21
22/**
23 * usb_gadget_get_string - fill out a string descriptor 
24 * @table: of c strings encoded using UTF-8
25 * @id: string id, from low byte of wValue in get string descriptor
26 * @buf: at least 256 bytes, must be 16-bit aligned
27 *
28 * Finds the UTF-8 string matching the ID, and converts it into a
29 * string descriptor in utf16-le.
30 * Returns length of descriptor (always even) or negative errno
31 *
32 * If your driver needs stings in multiple languages, you'll probably
33 * "switch (wIndex) { ... }"  in your ep0 string descriptor logic,
34 * using this routine after choosing which set of UTF-8 strings to use.
35 * Note that US-ASCII is a strict subset of UTF-8; any string bytes with
36 * the eighth bit set will be multibyte UTF-8 characters, not ISO-8859/1
37 * characters (which are also widely used in C strings).
38 */
39int
40usb_gadget_get_string (struct usb_gadget_strings *table, int id, u8 *buf)
41{
42	struct usb_string	*s;
43	int			len;
44
45	/* descriptor 0 has the language id */
46	if (id == 0) {
47		buf [0] = 4;
48		buf [1] = USB_DT_STRING;
49		buf [2] = (u8) table->language;
50		buf [3] = (u8) (table->language >> 8);
51		return 4;
52	}
53	for (s = table->strings; s && s->s; s++)
54		if (s->id == id)
55			break;
56
57	/* unrecognized: stall. */
58	if (!s || !s->s)
59		return -EINVAL;
60
61	/* string descriptors have length, tag, then UTF16-LE text */
62	len = min ((size_t) 126, strlen (s->s));
63	len = utf8s_to_utf16s(s->s, len, UTF16_LITTLE_ENDIAN,
64			(wchar_t *) &buf[2], 126);
65	if (len < 0)
66		return -EINVAL;
67	buf [0] = (len + 1) * 2;
68	buf [1] = USB_DT_STRING;
69	return buf [0];
70}
71EXPORT_SYMBOL_GPL(usb_gadget_get_string);