linux/drivers/usb/gadget/usbstring.c

// SPDX-License-Identifier: LGPL-2.1+
/*
 * Copyright (C) 2003 David Brownell
 */

#include <linux/errno.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/list.h>
#include <linux/string.h>
#include <linux/device.h>
#include <linux/nls.h>

#include <linux/usb/ch9.h>
#include <linux/usb/gadget.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, must be 16-bit aligned
 *
 * 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 (const struct usb_gadget_strings *table, int id, u8 *buf)
{ … }
EXPORT_SYMBOL_GPL(…);

/**
 * usb_validate_langid - validate usb language identifiers
 * @langid: usb language identifier
 *
 * Returns true for valid language identifier, otherwise false.
 */
bool usb_validate_langid(u16 langid)
{ … }
EXPORT_SYMBOL_GPL(…);