diff --git a/drivers/usb/serial/usb-serial.c b/drivers/usb/serial/usb-serial.c
index 0b39d013c505eb93209f6b45de10387b81daa118..ada400d6594b2d5a96578621ad53704a4bc7946a 100644
--- a/drivers/usb/serial/usb-serial.c
+++ b/drivers/usb/serial/usb-serial.c
@@ -402,10 +402,17 @@ static int serial_ioctl(struct tty_struct *tty,
 
 	dev_dbg(tty->dev, "%s - cmd 0x%.4x\n", __func__, cmd);
 
-	if (port->serial->type->ioctl)
-		retval = port->serial->type->ioctl(tty, cmd, arg);
-	else
-		retval = -ENOIOCTLCMD;
+	switch (cmd) {
+	case TIOCMIWAIT:
+		if (port->serial->type->tiocmiwait)
+			retval = port->serial->type->tiocmiwait(tty, arg);
+		break;
+	default:
+		if (port->serial->type->ioctl)
+			retval = port->serial->type->ioctl(tty, cmd, arg);
+		else
+			retval = -ENOIOCTLCMD;
+	}
 
 	return retval;
 }
diff --git a/include/linux/usb/serial.h b/include/linux/usb/serial.h
index 3f8f5e3c76d5c28a27a232aa6ce68d1fc9c5027c..9c8b53f80f4814476ae1c11d5c8404f8b74291bb 100644
--- a/include/linux/usb/serial.h
+++ b/include/linux/usb/serial.h
@@ -272,6 +272,7 @@ struct usb_serial_driver {
 	int  (*tiocmget)(struct tty_struct *tty);
 	int  (*tiocmset)(struct tty_struct *tty,
 			 unsigned int set, unsigned int clear);
+	int  (*tiocmiwait)(struct tty_struct *tty, unsigned long arg);
 	int  (*get_icount)(struct tty_struct *tty,
 			struct serial_icounter_struct *icount);
 	/* Called by the tty layer for port level work. There may or may not