tty: serial: fsl_lpuart: enable two stop bits for lpuart32

Add two stop bits support.
User can run the command to enable two stop bits for test:
stty  cstopb  -F /dev/ttyLPx
Signed-off-by: Fugang Duan <fugang.duan@nxp.com>
Signed-off-by: Sherry Sun <sherry.sun@nxp.com>
Link: https://lore.kernel.org/r/20210823081733.31941-1-sherry.sun@nxp.comSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/tty/serial/fsl_lpuart.c

@@ -2049,11 +2049,12 @@ lpuart32_set_termios(struct uart_port *port, struct ktermios *termios,
 {
 	struct lpuart_port *sport = container_of(port, struct lpuart_port, port);
 	unsigned long flags;
-	unsigned long ctrl, old_ctrl, modem;
+	unsigned long ctrl, old_ctrl, bd, modem;
 	unsigned int  baud;
 	unsigned int old_csize = old ? old->c_cflag & CSIZE : CS8;
 
 	ctrl = old_ctrl = lpuart32_read(&sport->port, UARTCTRL);
+	bd = lpuart32_read(&sport->port, UARTBAUD);
 	modem = lpuart32_read(&sport->port, UARTMODIR);
 	/*
 	 * only support CS8 and CS7, and for CS7 must enable PE.
@@ -2097,7 +2098,9 @@ lpuart32_set_termios(struct uart_port *port, struct ktermios *termios,
 	}
 
 	if (termios->c_cflag & CSTOPB)
-		termios->c_cflag &= ~CSTOPB;
+		bd |= UARTBAUD_SBNS;
+	else
+		bd &= ~UARTBAUD_SBNS;
 
 	/* parity must be enabled when CS7 to match 8-bits format */
 	if ((termios->c_cflag & CSIZE) == CS7)
@@ -2167,6 +2170,7 @@ lpuart32_set_termios(struct uart_port *port, struct ktermios *termios,
 	lpuart32_write(&sport->port, old_ctrl & ~(UARTCTRL_TE | UARTCTRL_RE),
 		       UARTCTRL);
 
+	lpuart32_write(&sport->port, bd, UARTBAUD);
 	lpuart32_serial_setbrg(sport, baud);
 	lpuart32_write(&sport->port, modem, UARTMODIR);
 	lpuart32_write(&sport->port, ctrl, UARTCTRL);