3 files changed, 10 insertions, 3 deletions

diff --git a/Documentation/serial/serial-rs485.txt b/Documentation/serial/serial-rs485.txt
index a4932387bbfb..c8878f821d1e 100644
--- a/Documentation/serial/serial-rs485.txt
+++ b/Documentation/serial/serial-rs485.txt
@@ -104,6 +104,9 @@
         rs485conf.flags |= SER_RS485_RTS_AFTER_SEND;
         rs485conf.delay_rts_after_send = ...;
 
+        /* Set this flag if you want to receive data even whilst sending data */
+        rs485conf.flags |= SER_RS485_RX_DURING_TX;
+
         if (ioctl (fd, TIOCSRS485, &rs485conf) < 0) {
                 /* Error handling. See errno. */
         }
diff --git a/drivers/tty/serial/atmel_serial.c b/drivers/tty/serial/atmel_serial.c
index af9b7814965a..c7232a916c1b 100644
--- a/drivers/tty/serial/atmel_serial.c
+++ b/drivers/tty/serial/atmel_serial.c
@@ -339,7 +339,8 @@ static void atmel_stop_tx(struct uart_port *port)
         /* Disable interrupts */
         UART_PUT_IDR(port, atmel_port->tx_done_mask);
 
-        if (atmel_port->rs485.flags & SER_RS485_ENABLED)
+        if ((atmel_port->rs485.flags & SER_RS485_ENABLED) &&
+            !(atmel_port->rs485.flags & SER_RS485_RX_DURING_TX))
                 atmel_start_rx(port);
 }
 
@@ -356,7 +357,8 @@ static void atmel_start_tx(struct uart_port *port)
                            really need this.*/
                         return;
 
-                if (atmel_port->rs485.flags & SER_RS485_ENABLED)
+                if ((atmel_port->rs485.flags & SER_RS485_ENABLED) &&
+                    !(atmel_port->rs485.flags & SER_RS485_RX_DURING_TX))
                         atmel_stop_rx(port);
 
                 /* re-enable PDC transmit */
@@ -680,7 +682,8 @@ static void atmel_tx_dma(struct uart_port *port)
                 /* Enable interrupts */
                 UART_PUT_IER(port, atmel_port->tx_done_mask);
         } else {
-                if (atmel_port->rs485.flags & SER_RS485_ENABLED) {
+                if ((atmel_port->rs485.flags & SER_RS485_ENABLED) &&
+                    !(atmel_port->rs485.flags & SER_RS485_RX_DURING_TX)) {
                         /* DMA done, stop TX, start RX for RS485 */
                         atmel_start_rx(port);
                 }
diff --git a/include/linux/serial.h b/include/linux/serial.h
index ef914061511e..97ff8e27a6cc 100644
--- a/include/linux/serial.h
+++ b/include/linux/serial.h
@@ -211,6 +211,7 @@ struct serial_rs485 {
 #define SER_RS485_RTS_ON_SEND           (1 << 1)
 #define SER_RS485_RTS_AFTER_SEND        (1 << 2)
 #define SER_RS485_RTS_BEFORE_SEND       (1 << 3)
+#define SER_RS485_RX_DURING_TX          (1 << 4)
         __u32   delay_rts_before_send;  /* Milliseconds */
         __u32   delay_rts_after_send;   /* Milliseconds */
         __u32   padding[5];             /* Memory is cheap, new structs