usbstring.c

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/*
 * Copyright (C) 2003 David Brownell
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU Lesser General Public License as published
 * by the Free Software Foundation; either version 2.1 of the License, or
 * (at your option) any later version.
 */

#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/init.h>
#include <linux/nls.h>

#include <linux/usb/ch9.h>
#include <linux/usb/gadget.h>


int
usb_gadget_get_string (struct usb_gadget_strings *table, int id, u8 *buf)
{
    struct usb_string   *s;
    int         len;

    /* 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));
    len = utf8s_to_utf16s(s->s, len, UTF16_LITTLE_ENDIAN,
            (wchar_t *) &buf[2], 126);
    if (len < 0)
        return -EINVAL;
    buf [0] = (len + 1) * 2;
    buf [1] = USB_DT_STRING;
    return buf [0];
}
EXPORT_SYMBOL_GPL(usb_gadget_get_string);