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91 lines
2.4 KiB
91 lines
2.4 KiB
// SPDX-License-Identifier: LGPL-2.1+ |
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/* |
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* Copyright (C) 2003 David Brownell |
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*/ |
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#include <linux/errno.h> |
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#include <linux/kernel.h> |
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#include <linux/module.h> |
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#include <linux/list.h> |
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#include <linux/string.h> |
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#include <linux/device.h> |
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#include <linux/nls.h> |
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#include <linux/usb/ch9.h> |
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#include <linux/usb/gadget.h> |
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/** |
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* usb_gadget_get_string - fill out a string descriptor |
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* @table: of c strings encoded using UTF-8 |
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* @id: string id, from low byte of wValue in get string descriptor |
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* @buf: at least 256 bytes, must be 16-bit aligned |
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* |
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* Finds the UTF-8 string matching the ID, and converts it into a |
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* string descriptor in utf16-le. |
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* Returns length of descriptor (always even) or negative errno |
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* |
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* If your driver needs stings in multiple languages, you'll probably |
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* "switch (wIndex) { ... }" in your ep0 string descriptor logic, |
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* using this routine after choosing which set of UTF-8 strings to use. |
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* Note that US-ASCII is a strict subset of UTF-8; any string bytes with |
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* the eighth bit set will be multibyte UTF-8 characters, not ISO-8859/1 |
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* characters (which are also widely used in C strings). |
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*/ |
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int |
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usb_gadget_get_string (const struct usb_gadget_strings *table, int id, u8 *buf) |
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{ |
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struct usb_string *s; |
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int len; |
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/* descriptor 0 has the language id */ |
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if (id == 0) { |
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buf [0] = 4; |
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buf [1] = USB_DT_STRING; |
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buf [2] = (u8) table->language; |
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buf [3] = (u8) (table->language >> 8); |
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return 4; |
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} |
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for (s = table->strings; s && s->s; s++) |
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if (s->id == id) |
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break; |
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/* unrecognized: stall. */ |
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if (!s || !s->s) |
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return -EINVAL; |
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/* string descriptors have length, tag, then UTF16-LE text */ |
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len = min((size_t)USB_MAX_STRING_LEN, strlen(s->s)); |
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len = utf8s_to_utf16s(s->s, len, UTF16_LITTLE_ENDIAN, |
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(wchar_t *) &buf[2], USB_MAX_STRING_LEN); |
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if (len < 0) |
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return -EINVAL; |
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buf [0] = (len + 1) * 2; |
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buf [1] = USB_DT_STRING; |
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return buf [0]; |
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} |
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EXPORT_SYMBOL_GPL(usb_gadget_get_string); |
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/** |
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* usb_validate_langid - validate usb language identifiers |
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* @langid: usb language identifier |
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* |
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* Returns true for valid language identifier, otherwise false. |
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*/ |
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bool usb_validate_langid(u16 langid) |
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{ |
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u16 primary_lang = langid & 0x3ff; /* bit [9:0] */ |
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u16 sub_lang = langid >> 10; /* bit [15:10] */ |
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switch (primary_lang) { |
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case 0: |
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case 0x62 ... 0xfe: |
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case 0x100 ... 0x3ff: |
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return false; |
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} |
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if (!sub_lang) |
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return false; |
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return true; |
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} |
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EXPORT_SYMBOL_GPL(usb_validate_langid);
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