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diff --git a/Documentation/devicetree/bindings/serial/rs485.txt b/Documentation/devicetree/bindings/serial/rs485.txt
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+* RS485 serial communications
+
+The RTS signal is capable of automatically controlling line direction for
+the built-in half-duplex mode.
+The properties described hereafter shall be given to a half-duplex capable
+UART node.
+
+Required properties:
+- rs485-rts-delay: prop-encoded-array <a b> where:
+  * a is the delay beteween rts signal and beginning of data sent in milliseconds.
+      it corresponds to the delay before sending data.
+  * b is the delay between end of data sent and rts signal in milliseconds
+      it corresponds to the delay after sending data and actual release of the line.
+
+Optional properties:
+- linux,rs485-enabled-at-boot-time: empty property telling to enable the rs485
+  feature at boot time. It can be disabled later with proper ioctl.
+- rs485-rx-during-tx: empty property that enables the receiving of data even
+  whilst sending data.
+
+RS485 example for Atmel USART:
+        usart0: serial@fff8c000 {
+                compatible = "atmel,at91sam9260-usart";
+                reg = <0xfff8c000 0x4000>;
+                interrupts = <7>;
+                atmel,use-dma-rx;
+                atmel,use-dma-tx;
+                linux,rs485-enabled-at-boot-time;
+                rs485-rts-delay = <0 200>;              // in milliseconds
+        };
+
diff --git a/Documentation/devicetree/bindings/tty/serial/atmel-usart.txt b/Documentation/devicetree/bindings/tty/serial/atmel-usart.txt
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+* Atmel Universal Synchronous Asynchronous Receiver/Transmitter (USART)
+
+Required properties:
+- compatible: Should be "atmel,<chip>-usart"
+  The compatible <chip> indicated will be the first SoC to support an
+  additional mode or an USART new feature.
+- reg: Should contain registers location and length
+- interrupts: Should contain interrupt
+
+Optional properties:
+- atmel,use-dma-rx: use of PDC or DMA for receiving data
+- atmel,use-dma-tx: use of PDC or DMA for transmitting data
+
+<chip> compatible description:
+- at91rm9200:  legacy USART support
+- at91sam9260: generic USART implementation for SAM9 SoCs
+
+Example:
+
+        usart0: serial@fff8c000 {
+                compatible = "atmel,at91sam9260-usart";
+                reg = <0xfff8c000 0x4000>;
+                interrupts = <7>;
+                atmel,use-dma-rx;
+                atmel,use-dma-tx;
+        };
+