usb/gadget/usbstring.c

1 // SPDX-License-Identifier: LGPL-2.1+
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
24  * Finds the UTF-8 string matching the ID, and converts it into a
25  * string descriptor in utf16-le.
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
36 usb_gadget_get_string (const struct usb_gadget_strings *table, int id, u8 *buf)  in usb_gadget_get_string()  argument
41 	/* descriptor 0 has the language id */  in usb_gadget_get_string()
42 	if (id == 0) {  in usb_gadget_get_string()
45 		buf [2] = (u8) table->language;  in usb_gadget_get_string()
46 		buf [3] = (u8) (table->language >> 8);  in usb_gadget_get_string()
49 	for (s = table->strings; s && s->s; s++)  in usb_gadget_get_string()
50 		if (s->id == id)  in usb_gadget_get_string()
54 	if (!s || !s->s)  in usb_gadget_get_string()
55 		return -EINVAL;  in usb_gadget_get_string()
57 	/* string descriptors have length, tag, then UTF16-LE text */  in usb_gadget_get_string()
58 	len = min((size_t)USB_MAX_STRING_LEN, strlen(s->s));  in usb_gadget_get_string()
59 	len = utf8s_to_utf16s(s->s, len, UTF16_LITTLE_ENDIAN,  in usb_gadget_get_string()
62 		return -EINVAL;  in usb_gadget_get_string()
70  * usb_validate_langid - validate usb language identifiers
71  * @langid: usb language identifier
73  * Returns true for valid language identifier, otherwise false.