usbstring.c 3.3 KB

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