avr32: add hardware handshake support to atmel_serial

Adds Hardware Handshake (aka RTS/CTS flow-control) support to
atmel_serial driver, as a termios flag.

For this to actually work, the platform code needs to configure the RTS
and CTS pins for use by the USART. This has been done for AVR32 as a
separate patch.

Signed-off-by: Peter Ma <pma@mediamatech.com>
Signed-off-by: Haavard Skinnemoen <haavard.skinnemoen@atmel.com>
Acked-by: Alan Cox <alan@lxorguk.ukuu.org.uk>

1 files changed, 8 insertions, 1 deletions

diff --git a/drivers/serial/atmel_serial.c b/drivers/serial/atmel_serial.c
index 8f58f7ff0dd7..b3497d7e5354 100644
--- a/drivers/serial/atmel_serial.c
+++ b/drivers/serial/atmel_serial.c
@@ -1020,7 +1020,8 @@ static void atmel_set_termios(struct uart_port *port, struct ktermios *termios,
 
         /* Get current mode register */
         mode = UART_GET_MR(port) & ~(ATMEL_US_USCLKS | ATMEL_US_CHRL
-                                        | ATMEL_US_NBSTOP | ATMEL_US_PAR);
+                                        | ATMEL_US_NBSTOP | ATMEL_US_PAR
+                                        | ATMEL_US_USMODE);
 
         baud = uart_get_baud_rate(port, termios, old, 0, port->uartclk / 16);
         quot = uart_get_divisor(port, baud);
@@ -1065,6 +1066,12 @@ static void atmel_set_termios(struct uart_port *port, struct ktermios *termios,
         } else
                 mode |= ATMEL_US_PAR_NONE;
 
+        /* hardware handshake (RTS/CTS) */
+        if (termios->c_cflag & CRTSCTS)
+                mode |= ATMEL_US_USMODE_HWHS;
+        else
+                mode |= ATMEL_US_USMODE_NORMAL;
+
         spin_lock_irqsave(&port->lock, flags);
 
         port->read_status_mask = ATMEL_US_OVRE;