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 <[e-mail]>
Signed-off-by: Greg Kroah-Hartman <[e-mail]>

drivers/char/pcmcia/synclink_cs.c

···
 	wake_up_interruptible(&info->status_event_wait_q);
 	wake_up_interruptible(&info->event_wait_q);
 
-	if (info->port.flags & ASYNC_CTS_FLOW) {
+	if (tty_port_cts_enabled(&info->port)) {
 		if (tty->hw_stopped) {
 			if (info->serial_signals & SerialSignal_CTS) {
 				if (debug_level >= DEBUG_LEVEL_ISR)

drivers/tty/amiserial.c

···
 				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))

drivers/tty/cyclades.c

···
 		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

drivers/tty/isicom.c

···
 					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;

drivers/tty/mxser.c

···
 			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;

drivers/tty/serial/mxs-auart.c

···
 
 	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;
 	}
 

drivers/tty/serial/serial_core.c

···
 				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;
···
 
 	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;

drivers/tty/synclink.c

···
 			}
 		}
 	
-		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) {

drivers/tty/synclink_gt.c

···
 	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) {

drivers/tty/synclinkmp.c

···
 			}
 		}
 
-		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) {

include/linux/tty.h

···
 	return port;
 }
 
+/* If the cts flow control is enabled, return true. */
+static inline bool tty_port_cts_enabled(struct tty_port *port)
+{
+	return port->flags & ASYNC_CTS_FLOW;
+}
+
 extern struct tty_struct *tty_port_tty_get(struct tty_port *port);
 extern void tty_port_tty_set(struct tty_port *port, struct tty_struct *tty);
 extern int tty_port_carrier_raised(struct tty_port *port);

net/irda/ircomm/ircomm_tty.c

···
 			goto put;
 		}
 	}
-	if (tty && self->port.flags & ASYNC_CTS_FLOW) {
+	if (tty && tty_port_cts_enabled(&self->port)) {
 		if (tty->hw_stopped) {
 			if (status & IRCOMM_CTS) {
 				IRDA_DEBUG(2,
···
 
 	seq_puts(m, "Flags:");
 	sep = ' ';
-	if (self->port.flags & ASYNC_CTS_FLOW) {
+	if (tty_port_cts_enabled(&self->port)) {
 		seq_printf(m, "%cASYNC_CTS_FLOW", sep);
 		sep = '|';
 	}

net/irda/ircomm/ircomm_tty_attach.c

···
 	 * will have to wait for the peer device (DCE) to raise the CTS
 	 * line.
 	 */
-	if ((self->port.flags & ASYNC_CTS_FLOW) &&
+	if (tty_port_cts_enabled(&self->port) &&
 			((self->settings.dce & IRCOMM_CTS) == 0)) {
 		IRDA_DEBUG(0, "%s(), waiting for CTS ...\n", __func__ );
 		goto put;