serial: add a new helper function

In most of the time, the driver needs to check if the cts flow control
is enabled. But now, the driver checks the ASYNC_CTS_FLOW flag manually,
which is not a grace way. So add a new wraper function to make the code
tidy and clean.

Signed-off-by: Huang Shijie <shijie8@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
diff --git a/drivers/tty/amiserial.c b/drivers/tty/amiserial.c
index 2b7535d..42d0a25 100644
--- a/drivers/tty/amiserial.c
+++ b/drivers/tty/amiserial.c
@@ -420,7 +420,7 @@
 				tty_hangup(port->tty);
 		}
 	}
-	if (port->flags & ASYNC_CTS_FLOW) {
+	if (tty_port_cts_enabled(port)) {
 		if (port->tty->hw_stopped) {
 			if (!(status & SER_CTS)) {
 #if (defined(SERIAL_DEBUG_INTR) || defined(SERIAL_DEBUG_FLOW))
diff --git a/drivers/tty/cyclades.c b/drivers/tty/cyclades.c
index e3954da..0a6a0bc 100644
--- a/drivers/tty/cyclades.c
+++ b/drivers/tty/cyclades.c
@@ -727,7 +727,7 @@
 		else
 			tty_hangup(tty);
 	}
-	if ((mdm_change & CyCTS) && (info->port.flags & ASYNC_CTS_FLOW)) {
+	if ((mdm_change & CyCTS) && tty_port_cts_enabled(&info->port)) {
 		if (tty->hw_stopped) {
 			if (mdm_status & CyCTS) {
 				/* cy_start isn't used
diff --git a/drivers/tty/isicom.c b/drivers/tty/isicom.c
index 99cf22e..d7492e1 100644
--- a/drivers/tty/isicom.c
+++ b/drivers/tty/isicom.c
@@ -600,7 +600,7 @@
 					port->status &= ~ISI_DCD;
 			}
 
-			if (port->port.flags & ASYNC_CTS_FLOW) {
+			if (tty_port_cts_enabled(&port->port)) {
 				if (tty->hw_stopped) {
 					if (header & ISI_CTS) {
 						port->port.tty->hw_stopped = 0;
diff --git a/drivers/tty/mxser.c b/drivers/tty/mxser.c
index bb2da4c..cfda47d 100644
--- a/drivers/tty/mxser.c
+++ b/drivers/tty/mxser.c
@@ -830,7 +830,7 @@
 			wake_up_interruptible(&port->port.open_wait);
 	}
 
-	if (port->port.flags & ASYNC_CTS_FLOW) {
+	if (tty_port_cts_enabled(&port->port)) {
 		if (tty->hw_stopped) {
 			if (status & UART_MSR_CTS) {
 				tty->hw_stopped = 0;
diff --git a/drivers/tty/serial/mxs-auart.c b/drivers/tty/serial/mxs-auart.c
index 3a667ee..dafeef2 100644
--- a/drivers/tty/serial/mxs-auart.c
+++ b/drivers/tty/serial/mxs-auart.c
@@ -262,7 +262,7 @@
 
 	ctrl &= ~AUART_CTRL2_RTSEN;
 	if (mctrl & TIOCM_RTS) {
-		if (u->state->port.flags & ASYNC_CTS_FLOW)
+		if (tty_port_cts_enabled(&u->state->port))
 			ctrl |= AUART_CTRL2_RTSEN;
 	}
 
diff --git a/drivers/tty/serial/serial_core.c b/drivers/tty/serial/serial_core.c
index bb5f236..137b25c 100644
--- a/drivers/tty/serial/serial_core.c
+++ b/drivers/tty/serial/serial_core.c
@@ -176,7 +176,7 @@
 				uart_set_mctrl(uport, TIOCM_RTS | TIOCM_DTR);
 		}
 
-		if (port->flags & ASYNC_CTS_FLOW) {
+		if (tty_port_cts_enabled(port)) {
 			spin_lock_irq(&uport->lock);
 			if (!(uport->ops->get_mctrl(uport) & TIOCM_CTS))
 				tty->hw_stopped = 1;
@@ -2509,7 +2509,7 @@
 
 	uport->icount.cts++;
 
-	if (port->flags & ASYNC_CTS_FLOW) {
+	if (tty_port_cts_enabled(port)) {
 		if (tty->hw_stopped) {
 			if (status) {
 				tty->hw_stopped = 0;
diff --git a/drivers/tty/synclink.c b/drivers/tty/synclink.c
index 666aa14..70e3a52 100644
--- a/drivers/tty/synclink.c
+++ b/drivers/tty/synclink.c
@@ -1359,7 +1359,7 @@
 			}
 		}
 	
-		if ( (info->port.flags & ASYNC_CTS_FLOW) && 
+		if (tty_port_cts_enabled(&info->port) &&
 		     (status & MISCSTATUS_CTS_LATCHED) ) {
 			if (info->port.tty->hw_stopped) {
 				if (status & MISCSTATUS_CTS) {
diff --git a/drivers/tty/synclink_gt.c b/drivers/tty/synclink_gt.c
index 45f6136..b38e954 100644
--- a/drivers/tty/synclink_gt.c
+++ b/drivers/tty/synclink_gt.c
@@ -2053,7 +2053,7 @@
 	wake_up_interruptible(&info->event_wait_q);
 	info->pending_bh |= BH_STATUS;
 
-	if (info->port.flags & ASYNC_CTS_FLOW) {
+	if (tty_port_cts_enabled(&info->port)) {
 		if (info->port.tty) {
 			if (info->port.tty->hw_stopped) {
 				if (info->signals & SerialSignal_CTS) {
diff --git a/drivers/tty/synclinkmp.c b/drivers/tty/synclinkmp.c
index 53429c8..f17d9f3 100644
--- a/drivers/tty/synclinkmp.c
+++ b/drivers/tty/synclinkmp.c
@@ -2500,7 +2500,7 @@
 			}
 		}
 
-		if ( (info->port.flags & ASYNC_CTS_FLOW) &&
+		if (tty_port_cts_enabled(&info->port) &&
 		     (status & MISCSTATUS_CTS_LATCHED) ) {
 			if ( info->port.tty ) {
 				if (info->port.tty->hw_stopped) {