tty/serial_core: Introduce lock mechanism for RS485

Introduce an homogeneous lock system between setting and using the rs485
data of the uart_port.

This patch should not be split into multiple ones in order to avoid
leaving the tree in an unstable state.

Acked-by: Nicolas Ferre <nicolas.ferre@atmel.com>
Reviewed-by: Alan Cox <alan@linux.intel.com>
Suggested-by: Alan Cox <alan@linux.intel.com>
Cc: Nicolas Ferre <nicolas.ferre@atmel.com>
Cc: Jiri Slaby <jslaby@suse.cz>
Cc: One Thousand Gnomes <gnomes@lxorguk.ukuu.org.uk>
Signed-off-by: Ricardo Ribalda Delgado <ricardo.ribalda@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 1 insertions, 4 deletions

diff --git a/drivers/tty/serial/mcf.c b/drivers/tty/serial/mcf.c
index d7be1f18545b..fdd5c7bd1e8d 100644
--- a/drivers/tty/serial/mcf.c
+++ b/drivers/tty/serial/mcf.c
@@ -257,12 +257,12 @@ static void mcf_set_termios(struct uart_port *port, struct ktermios *termios,
                 mr2 |= MCFUART_MR2_TXCTS;
         }
 
+        spin_lock_irqsave(&port->lock, flags);
         if (port->rs485.flags & SER_RS485_ENABLED) {
                 dev_dbg(port->dev, "Setting UART to RS485\n");
                 mr2 |= MCFUART_MR2_TXRTS;
         }
 
-        spin_lock_irqsave(&port->lock, flags);
         uart_update_timeout(port, termios->c_cflag, baud);
         writeb(MCFUART_UCR_CMDRESETRX, port->membase + MCFUART_UCR);
         writeb(MCFUART_UCR_CMDRESETTX, port->membase + MCFUART_UCR);
@@ -442,10 +442,8 @@ static int mcf_verify_port(struct uart_port *port, struct serial_struct *ser)
 static int mcf_config_rs485(struct uart_port *port, struct serial_rs485 *rs485)
 {
         struct mcf_uart *pp = container_of(port, struct mcf_uart, port);
-        unsigned long flags;
         unsigned char mr1, mr2;
 
-        spin_lock_irqsave(&port->lock, flags);
         /* Get mode registers */
         mr1 = readb(port->membase + MCFUART_UMR);
         mr2 = readb(port->membase + MCFUART_UMR);
@@ -460,7 +458,6 @@ static int mcf_config_rs485(struct uart_port *port, struct serial_rs485 *rs485)
         writeb(mr1, port->membase + MCFUART_UMR);
         writeb(mr2, port->membase + MCFUART_UMR);
         port->rs485 = *rs485;
-        spin_unlock_irqrestore(&port->lock, flags);
 
         return 0;
 }