1 // SPDX-License-Identifier: LGPL-2.1+ 2 /* 3 * Copyright (C) 2003 David Brownell 4 * 5 * Ported to U-Boot by: Thomas Smits <ts.smits@gmail.com> and 6 * Remy Bohmer <linux@bohmer.net> 7 */ 8 9 #include <common.h> 10 #include <linux/errno.h> 11 #include <linux/usb/ch9.h> 12 #include <linux/usb/gadget.h> 13 14 #include <asm/unaligned.h> 15 16 17 static int utf8_to_utf16le(const char *s, __le16 *cp, unsigned len) 18 { 19 int count = 0; 20 u8 c; 21 u16 uchar; 22 23 /* 24 * this insists on correct encodings, though not minimal ones. 25 * BUT it currently rejects legit 4-byte UTF-8 code points, 26 * which need surrogate pairs. (Unicode 3.1 can use them.) 27 */ 28 while (len != 0 && (c = (u8) *s++) != 0) { 29 if ((c & 0x80)) { 30 /* 31 * 2-byte sequence: 32 * 00000yyyyyxxxxxx = 110yyyyy 10xxxxxx 33 */ 34 if ((c & 0xe0) == 0xc0) { 35 uchar = (c & 0x1f) << 6; 36 37 c = (u8) *s++; 38 if ((c & 0xc0) != 0x80) 39 goto fail; 40 c &= 0x3f; 41 uchar |= c; 42 43 /* 44 * 3-byte sequence (most CJKV characters): 45 * zzzzyyyyyyxxxxxx = 1110zzzz 10yyyyyy 10xxxxxx 46 */ 47 } else if ((c & 0xf0) == 0xe0) { 48 uchar = (c & 0x0f) << 12; 49 50 c = (u8) *s++; 51 if ((c & 0xc0) != 0x80) 52 goto fail; 53 c &= 0x3f; 54 uchar |= c << 6; 55 56 c = (u8) *s++; 57 if ((c & 0xc0) != 0x80) 58 goto fail; 59 c &= 0x3f; 60 uchar |= c; 61 62 /* no bogus surrogates */ 63 if (0xd800 <= uchar && uchar <= 0xdfff) 64 goto fail; 65 66 /* 67 * 4-byte sequence (surrogate pairs, currently rare): 68 * 11101110wwwwzzzzyy + 110111yyyyxxxxxx 69 * = 11110uuu 10uuzzzz 10yyyyyy 10xxxxxx 70 * (uuuuu = wwww + 1) 71 * FIXME accept the surrogate code points (only) 72 */ 73 } else 74 goto fail; 75 } else 76 uchar = c; 77 put_unaligned_le16(uchar, cp++); 78 count++; 79 len--; 80 } 81 return count; 82 fail: 83 return -1; 84 } 85 86 87 /** 88 * usb_gadget_get_string - fill out a string descriptor 89 * @table: of c strings encoded using UTF-8 90 * @id: string id, from low byte of wValue in get string descriptor 91 * @buf: at least 256 bytes 92 * 93 * Finds the UTF-8 string matching the ID, and converts it into a 94 * string descriptor in utf16-le. 95 * Returns length of descriptor (always even) or negative errno 96 * 97 * If your driver needs stings in multiple languages, you'll probably 98 * "switch (wIndex) { ... }" in your ep0 string descriptor logic, 99 * using this routine after choosing which set of UTF-8 strings to use. 100 * Note that US-ASCII is a strict subset of UTF-8; any string bytes with 101 * the eighth bit set will be multibyte UTF-8 characters, not ISO-8859/1 102 * characters (which are also widely used in C strings). 103 */ 104 int 105 usb_gadget_get_string(struct usb_gadget_strings *table, int id, u8 *buf) 106 { 107 struct usb_string *s; 108 int len; 109 110 if (!table) 111 return -EINVAL; 112 113 /* descriptor 0 has the language id */ 114 if (id == 0) { 115 buf[0] = 4; 116 buf[1] = USB_DT_STRING; 117 buf[2] = (u8) table->language; 118 buf[3] = (u8) (table->language >> 8); 119 return 4; 120 } 121 for (s = table->strings; s && s->s; s++) 122 if (s->id == id) 123 break; 124 125 /* unrecognized: stall. */ 126 if (!s || !s->s) 127 return -EINVAL; 128 129 /* string descriptors have length, tag, then UTF16-LE text */ 130 len = min((size_t) 126, strlen(s->s)); 131 memset(buf + 2, 0, 2 * len); /* zero all the bytes */ 132 len = utf8_to_utf16le(s->s, (__le16 *)&buf[2], len); 133 if (len < 0) 134 return -EINVAL; 135 buf[0] = (len + 1) * 2; 136 buf[1] = USB_DT_STRING; 137 return buf[0]; 138 } 139