diff --git a/drivers/usb/gadget/function/u_serial.c b/drivers/usb/gadget/function/u_serial.c
index d73618475664..9256588624bb 100644
--- a/drivers/usb/gadget/function/u_serial.c
+++ b/drivers/usb/gadget/function/u_serial.c
@@ -613,7 +613,8 @@ static void gs_write_complete(struct usb_ep *ep, struct usb_request *req)
 		/* FALL THROUGH */
 	case 0:
 		/* normal completion */
-		gs_start_tx(port);
+		if (port->port_usb)
+			gs_start_tx(port);
 		break;
 
 	case -ESHUTDOWN:
@@ -1012,6 +1013,78 @@ static int gs_break_ctl(struct tty_struct *tty, int duration)
 	return status;
 }
 
+static int gs_tiocmget(struct tty_struct *tty)
+{
+	struct gs_port	*port = tty->driver_data;
+	struct gserial	*gser;
+	unsigned int result = 0;
+
+	spin_lock_irq(&port->port_lock);
+	gser = port->port_usb;
+	if (!gser) {
+		result = -ENODEV;
+		goto fail;
+	}
+
+	if (gser->get_dtr)
+		result |= (gser->get_dtr(gser) ? TIOCM_DTR : 0);
+
+	if (gser->get_rts)
+		result |= (gser->get_rts(gser) ? TIOCM_RTS : 0);
+
+	if (gser->serial_state & TIOCM_CD)
+		result |= TIOCM_CD;
+
+	if (gser->serial_state & TIOCM_RI)
+		result |= TIOCM_RI;
+fail:
+	spin_unlock_irq(&port->port_lock);
+	return result;
+}
+
+static int gs_tiocmset(struct tty_struct *tty,
+	unsigned int set, unsigned int clear)
+{
+	struct gs_port	*port = tty->driver_data;
+	struct gserial *gser;
+	int	status = 0;
+
+	spin_lock_irq(&port->port_lock);
+	gser = port->port_usb;
+	if (!gser) {
+		status = -ENODEV;
+		goto fail;
+	}
+
+	if (set & TIOCM_RI) {
+		if (gser->send_ring_indicator) {
+			gser->serial_state |= TIOCM_RI;
+			status = gser->send_ring_indicator(gser, 1);
+		}
+	}
+	if (clear & TIOCM_RI) {
+		if (gser->send_ring_indicator) {
+			gser->serial_state &= ~TIOCM_RI;
+			status = gser->send_ring_indicator(gser, 0);
+		}
+	}
+	if (set & TIOCM_CD) {
+		if (gser->send_carrier_detect) {
+			gser->serial_state |= TIOCM_CD;
+			status = gser->send_carrier_detect(gser, 1);
+		}
+	}
+	if (clear & TIOCM_CD) {
+		if (gser->send_carrier_detect) {
+			gser->serial_state &= ~TIOCM_CD;
+			status = gser->send_carrier_detect(gser, 0);
+		}
+	}
+fail:
+	spin_unlock_irq(&port->port_lock);
+	return status;
+}
+
 static const struct tty_operations gs_tty_ops = {
 	.open =			gs_open,
 	.close =		gs_close,
@@ -1022,6 +1095,8 @@ static const struct tty_operations gs_tty_ops = {
 	.chars_in_buffer =	gs_chars_in_buffer,
 	.unthrottle =		gs_unthrottle,
 	.break_ctl =		gs_break_ctl,
+	.tiocmget  =		gs_tiocmget,
+	.tiocmset  =		gs_tiocmset,
 };
 
 /*-------------------------------------------------------------------------*/
@@ -1301,7 +1376,8 @@ static int userial_init(void)
 
 	gs_tty_driver->type = TTY_DRIVER_TYPE_SERIAL;
 	gs_tty_driver->subtype = SERIAL_TYPE_NORMAL;
-	gs_tty_driver->flags = TTY_DRIVER_REAL_RAW | TTY_DRIVER_DYNAMIC_DEV;
+	gs_tty_driver->flags = TTY_DRIVER_REAL_RAW | TTY_DRIVER_DYNAMIC_DEV
+				| TTY_DRIVER_RESET_TERMIOS;
 	gs_tty_driver->init_termios = tty_std_termios;
 
 	/* 9600-8-N-1 ... matches defaults expected by "usbser.sys" on
diff --git a/drivers/usb/gadget/function/u_serial.h b/drivers/usb/gadget/function/u_serial.h
index c20210c0babd..a0e100a5e635 100644
--- a/drivers/usb/gadget/function/u_serial.h
+++ b/drivers/usb/gadget/function/u_serial.h
@@ -45,11 +45,18 @@ struct gserial {
 
 	/* REVISIT avoid this CDC-ACM support harder ... */
 	struct usb_cdc_line_coding port_line_coding;	/* 9600-8-N-1 etc */
+	u16				serial_state;
+
+	/* control signal callbacks*/
+	unsigned int (*get_dtr)(struct gserial *p);
+	unsigned int (*get_rts)(struct gserial *p);
 
 	/* notification callbacks */
 	void (*connect)(struct gserial *p);
 	void (*disconnect)(struct gserial *p);
 	int (*send_break)(struct gserial *p, int duration);
+	unsigned int (*send_carrier_detect)(struct gserial *p, unsigned int);
+	unsigned int (*send_ring_indicator)(struct gserial *p, unsigned int);
 };
 
 /* utilities to allocate/free request and buffer */