2 files changed, 10 insertions, 1 deletions

diff --git a/Documentation/devicetree/bindings/tty/serial/fsl-mxs-auart.txt b/Documentation/devicetree/bindings/tty/serial/fsl-mxs-auart.txt
index 2c00ec64628e..59a40f18d551 100644
--- a/Documentation/devicetree/bindings/tty/serial/fsl-mxs-auart.txt
+++ b/Documentation/devicetree/bindings/tty/serial/fsl-mxs-auart.txt
@@ -10,6 +10,10 @@ Required properties:
   Refer to dma.txt and fsl-mxs-dma.txt for details.
 - dma-names: "rx" for RX channel, "tx" for TX channel.
 
+Optional properties:
+- fsl,uart-has-rtscts : Indicate the UART has RTS and CTS lines,
+        it also means you enable the DMA support for this UART.
+
 Example:
 auart0: serial@8006a000 {
         compatible = "fsl,imx28-auart", "fsl,imx23-auart";
diff --git a/drivers/tty/serial/mxs-auart.c b/drivers/tty/serial/mxs-auart.c
index 736e95c1ac4e..eac7b585bc0c 100644
--- a/drivers/tty/serial/mxs-auart.c
+++ b/drivers/tty/serial/mxs-auart.c
@@ -137,6 +137,7 @@ struct mxs_auart_port {
 #define MXS_AUART_DMA_ENABLED   0x2
 #define MXS_AUART_DMA_TX_SYNC   2  /* bit 2 */
 #define MXS_AUART_DMA_RX_READY  3  /* bit 3 */
+#define MXS_AUART_RTSCTS        4  /* bit 4 */
         unsigned long flags;
         unsigned int ctrl;
         enum mxs_auart_type devtype;
@@ -639,7 +640,8 @@ static void mxs_auart_settermios(struct uart_port *u,
                  * we can only implement the DMA support for auart
                  * in mx28.
                  */
-                if (is_imx28_auart(s) && (s->flags & MXS_AUART_DMA_CONFIG)) {
+                if (is_imx28_auart(s) && (s->flags & MXS_AUART_DMA_CONFIG)
+                                && test_bit(MXS_AUART_RTSCTS, &s->flags)) {
                         if (!mxs_auart_dma_init(s))
                                 /* enable DMA tranfer */
                                 ctrl2 |= AUART_CTRL2_TXDMAE | AUART_CTRL2_RXDMAE
@@ -1009,6 +1011,9 @@ static int serial_mxs_probe_dt(struct mxs_auart_port *s,
 
         s->flags |= MXS_AUART_DMA_CONFIG;
 
+        if (of_get_property(np, "fsl,uart-has-rtscts", NULL))
+                set_bit(MXS_AUART_RTSCTS, &s->flags);
+
         return 0;
 }