2 * Copyright (C) 2003 David Brownell
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.
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>
18 #include <linux/usb/ch9.h>
19 #include <linux/usb/gadget.h>
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
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
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).
40 usb_gadget_get_string (struct usb_gadget_strings
*table
, int id
, u8
*buf
)
45 /* descriptor 0 has the language id */
48 buf
[1] = USB_DT_STRING
;
49 buf
[2] = (u8
) table
->language
;
50 buf
[3] = (u8
) (table
->language
>> 8);
53 for (s
= table
->strings
; s
&& s
->s
; s
++)
57 /* unrecognized: stall. */
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);
67 buf
[0] = (len
+ 1) * 2;
68 buf
[1] = USB_DT_STRING
;
71 EXPORT_SYMBOL_GPL(usb_gadget_get_string
);
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