Add device function for USB serial console

Add device funtion for usb serial console, so we can open /dev/console
when we use a usb serial device as console.

(Typecast removed as noted by Sergei Shtylyov)
Signed-off-by: Kevin Hao <kexin.hao@windriver.com>
Signed-off-by: Alan Cox <alan@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

drivers/usb/serial/console.c

@@ -241,12 +241,25 @@ static void usb_console_write(struct console *co,
 	}
 }
 
+static struct tty_driver *usb_console_device(struct console *co, int *index)
+{
+	struct tty_driver **p = (struct tty_driver **)co->data;
+
+	if (!*p)
+		return NULL;
+
+	*index = co->index;
+	return *p;
+}
+
 static struct console usbcons = {
 	.name =		"ttyUSB",
 	.write =	usb_console_write,
+	.device =	usb_console_device,
 	.setup =	usb_console_setup,
 	.flags =	CON_PRINTBUFFER,
 	.index =	-1,
+	.data = 	&usb_serial_tty_driver,
 };
 
 void usb_serial_console_disconnect(struct usb_serial *serial)