diff options
Diffstat (limited to 'drivers/usb/gadget/usbstring.c')
| -rw-r--r-- | drivers/usb/gadget/usbstring.c | 134 |
1 files changed, 134 insertions, 0 deletions
diff --git a/drivers/usb/gadget/usbstring.c b/drivers/usb/gadget/usbstring.c new file mode 100644 index 000000000..168f75f7a --- /dev/null +++ b/drivers/usb/gadget/usbstring.c @@ -0,0 +1,134 @@ +/* + * 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. + * + * Ported to U-boot by: Thomas Smits <ts.smits@gmail.com> and + * Remy Bohmer <linux@bohmer.net> + */ + +#include <common.h> +#include <asm/errno.h> +#include <linux/usb/ch9.h> +#include <linux/usb/gadget.h> + +#include <asm/unaligned.h> + + +static int utf8_to_utf16le(const char *s, __le16 *cp, unsigned len) +{ + int count = 0; + u8 c; + u16 uchar; + + /* this insists on correct encodings, though not minimal ones. + * BUT it currently rejects legit 4-byte UTF-8 code points, + * which need surrogate pairs. (Unicode 3.1 can use them.) + */ + while (len != 0 && (c = (u8) *s++) != 0) { + if ((c & 0x80)) { + // 2-byte sequence: + // 00000yyyyyxxxxxx = 110yyyyy 10xxxxxx + if ((c & 0xe0) == 0xc0) { + uchar = (c & 0x1f) << 6; + + c = (u8) *s++; + if ((c & 0xc0) != 0x80) + goto fail; + c &= 0x3f; + uchar |= c; + + // 3-byte sequence (most CJKV characters): + // zzzzyyyyyyxxxxxx = 1110zzzz 10yyyyyy 10xxxxxx + } else if ((c & 0xf0) == 0xe0) { + uchar = (c & 0x0f) << 12; + + c = (u8) *s++; + if ((c & 0xc0) != 0x80) + goto fail; + c &= 0x3f; + uchar |= c << 6; + + c = (u8) *s++; + if ((c & 0xc0) != 0x80) + goto fail; + c &= 0x3f; + uchar |= c; + + /* no bogus surrogates */ + if (0xd800 <= uchar && uchar <= 0xdfff) + goto fail; + + // 4-byte sequence (surrogate pairs, currently rare): + // 11101110wwwwzzzzyy + 110111yyyyxxxxxx + // = 11110uuu 10uuzzzz 10yyyyyy 10xxxxxx + // (uuuuu = wwww + 1) + // FIXME accept the surrogate code points (only) + + } else + goto fail; + } else + uchar = c; + put_unaligned_le16(uchar, cp++); + count++; + len--; + } + return count; +fail: + return -1; +} + + +/** + * 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; + + /* 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]; +} + |