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- // SPDX-License-Identifier: LGPL-2.1+
- /*
- * Copyright (C) 2003 David Brownell
- *
- * Ported to U-Boot by: Thomas Smits <ts.smits@gmail.com> and
- * Remy Bohmer <linux@bohmer.net>
- */
- #include <common.h>
- #include <linux/errno.h>
- #include <linux/usb/ch9.h>
- #include <linux/usb/gadget.h>
- #include <linux/utf.h>
- /**
- * usb_gadget_get_string - fill out a string descriptor
- * @table: of c strings encoded using UTF-8
- * @id: string id, from low byte of wValue in get string descriptor
- * @buf: at least 256 bytes
- *
- * Finds the UTF-8 string matching the ID, and converts it into a
- * string descriptor in utf16-le.
- * Returns length of descriptor (always even) or negative errno
- *
- * If your driver needs stings in multiple languages, you'll probably
- * "switch (wIndex) { ... }" in your ep0 string descriptor logic,
- * using this routine after choosing which set of UTF-8 strings to use.
- * Note that US-ASCII is a strict subset of UTF-8; any string bytes with
- * the eighth bit set will be multibyte UTF-8 characters, not ISO-8859/1
- * characters (which are also widely used in C strings).
- */
- int
- usb_gadget_get_string(struct usb_gadget_strings *table, int id, u8 *buf)
- {
- struct usb_string *s;
- int len;
- if (!table)
- return -EINVAL;
- /* descriptor 0 has the language id */
- if (id == 0) {
- buf[0] = 4;
- buf[1] = USB_DT_STRING;
- buf[2] = (u8) table->language;
- buf[3] = (u8) (table->language >> 8);
- return 4;
- }
- for (s = table->strings; s && s->s; s++)
- if (s->id == id)
- break;
- /* unrecognized: stall. */
- if (!s || !s->s)
- return -EINVAL;
- /* string descriptors have length, tag, then UTF16-LE text */
- len = min((size_t) 126, strlen(s->s));
- memset(buf + 2, 0, 2 * len); /* zero all the bytes */
- len = utf8_to_utf16le(s->s, (__le16 *)&buf[2], len);
- if (len < 0)
- return -EINVAL;
- buf[0] = (len + 1) * 2;
- buf[1] = USB_DT_STRING;
- return buf[0];
- }
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