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diff --git a/Documentation/devicetree/bindings/tty/serial/of-serial.txt b/Documentation/devicetree/bindings/tty/serial/of-serial.txt
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+* UART (Universal Asynchronous Receiver/Transmitter)
+
+Required properties:
+- compatible : one of:
+        - "ns8250"
+        - "ns16450"
+        - "ns16550a"
+        - "ns16550"
+        - "ns16750"
+        - "ns16850"
+        - "nvidia,tegra250-uart"
+        - "ibm,qpace-nwp-serial"
+        - "serial" if the port type is unknown.
+- reg : offset and length of the register set for the device.
+- interrupts : should contain uart interrupt.
+- clock-frequency : the input clock frequency for the UART.
+
+Optional properties:
+- current-speed : the current active speed of the UART.
+- reg-offset : offset to apply to the mapbase from the start of the registers.
+- reg-shift : quantity to shift the register offsets by.
+- used-by-rtas : set to indicate that the port is in use by the OpenFirmware
+  RTAS and should not be registered.
+
+Example:
+
+        uart@80230000 {
+                compatible = "ns8250";
+                reg = <0x80230000 0x100>;
+                clock-frequency = <3686400>;
+                interrupts = <10>;
+                reg-shift = <2>;
+        };