serial: xilinx_uartps: set_termios sets flowcontrol

Let set_termios enable/disable automatic flow control.
set_mctrl should not touch automatic flow control.

Signed-off-by: Maarten Brock <m.brock@vanmierlo.com>
Signed-off-by: Shubhrajyoti Datta <shubhrajyoti.datta@xilinx.com>
Link: https://lore.kernel.org/r/1574687731-21563-2-git-send-email-shubhrajyoti.datta@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/tty/serial/xilinx_uartps.c

@@ -690,7 +690,7 @@ static void cdns_uart_break_ctl(struct uart_port *port, int ctl)
 static void cdns_uart_set_termios(struct uart_port *port,
 				struct ktermios *termios, struct ktermios *old)
 {
-	unsigned int cval = 0;
+	u32 cval = 0;
 	unsigned int baud, minbaud, maxbaud;
 	unsigned long flags;
 	unsigned int ctrl_reg, mode_reg, val;
@@ -811,6 +811,13 @@ static void cdns_uart_set_termios(struct uart_port *port,
 	cval |= mode_reg & 1;
 	writel(cval, port->membase + CDNS_UART_MR);
 
+	cval = readl(port->membase + CDNS_UART_MODEMCR);
+	if (termios->c_cflag & CRTSCTS)
+		cval |= CDNS_UART_MODEMCR_FCM;
+	else
+		cval &= ~CDNS_UART_MODEMCR_FCM;
+	writel(cval, port->membase + CDNS_UART_MODEMCR);
+
 	spin_unlock_irqrestore(&port->lock, flags);
 }
 
@@ -1045,12 +1052,9 @@ static void cdns_uart_set_mctrl(struct uart_port *port, unsigned int mctrl)
 	val = readl(port->membase + CDNS_UART_MODEMCR);
 	mode_reg = readl(port->membase + CDNS_UART_MR);
 
-	val &= ~(CDNS_UART_MODEMCR_RTS | CDNS_UART_MODEMCR_DTR |
-		 CDNS_UART_MODEMCR_FCM);
+	val &= ~(CDNS_UART_MODEMCR_RTS | CDNS_UART_MODEMCR_DTR);
 	mode_reg &= ~CDNS_UART_MR_CHMODE_MASK;
 
-	if (mctrl & TIOCM_RTS || mctrl & TIOCM_DTR)
-		val |= CDNS_UART_MODEMCR_FCM;
 	if (mctrl & TIOCM_LOOP)
 		mode_reg |= CDNS_UART_MR_CHMODE_L_LOOP;
 	else