1 files changed, 65 insertions, 0 deletions
diff --git a/drivers/usb/gadget/usbstring.c b/drivers/usb/gadget/usbstring.c
new file mode 100644
index 00000000000..4617a95bd0a
--- /dev/null
+++ b/drivers/usb/gadget/usbstring.c
@@ -0,0 +1,65 @@
+// SPDX-License-Identifier: LGPL-2.1+
+/*
+ * Copyright (C) 2003 David Brownell
+ *
+ * Ported to U-Boot by: Thomas Smits <ts.smits@gmail.com> and
+ *                      Remy Bohmer <linux@bohmer.net>
+ */
+
+#include <linux/errno.h>
+#include <linux/usb/ch9.h>
+#include <linux/usb/gadget.h>
+#include <linux/utf.h>
+
+/**
+ * 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;
+
+	if (!table)
+		return -EINVAL;
+
+	/* 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];
+}