tty: cadence: Document DT binding

Add binding documentation for the Cadence UART.

Signed-off-by: Soren Brinkmann <soren.brinkmann@xilinx.com>
Acked-by: Peter Crosthwaite <peter.crosthwaite@xilinx.com>
Acked-by: Rob Herring <robh@kernel.org>
Tested-by: Michal Simek <michal.simek@xilinx.com>
Signed-off-by: Michal Simek <michal.simek@xilinx.com>
(cherry picked from commit 09b6771798f262bedba51bbb66027564b0ff226e)

diff --git a/Documentation/devicetree/bindings/serial/cdns,uart.txt b/Documentation/devicetree/bindings/serial/cdns,uart.txt
new file mode 100644 (file)
index 0000000..a3eb154
--- /dev/null
+++ b/Documentation/devicetree/bindings/serial/cdns,uart.txt
@@ -0,0 +1,20 @@
+Binding for Cadence UART Controller
+
+Required properties:
+- compatible : should be "cdns,uart-r1p8", or "xlnx,xuartps"
+- reg: Should contain UART controller registers location and length.
+- interrupts: Should contain UART controller interrupts.
+- clocks: Must contain phandles to the UART clocks
+  See ../clocks/clock-bindings.txt for details.
+- clock-names: Tuple to identify input clocks, must contain "uart_clk" and "pclk"
+  See ../clocks/clock-bindings.txt for details.
+
+
+Example:
+       uart@e0000000 {
+               compatible = "cdns,uart-r1p8";
+               clocks = <&clkc 23>, <&clkc 40>;
+               clock-names = "uart_clk", "pclk";
+               reg = <0xE0000000 0x1000>;
+               interrupts = <0 27 4>;
+       };