ASoC: Tegra DAS: Add device tree binding

Signed-off-by: Stephen Warren <swarren@nvidia.com>
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
diff --git a/Documentation/devicetree/bindings/sound/tegra20-das.txt b/Documentation/devicetree/bindings/sound/tegra20-das.txt
new file mode 100644
index 0000000..6de3a7e
--- /dev/null
+++ b/Documentation/devicetree/bindings/sound/tegra20-das.txt
@@ -0,0 +1,12 @@
+NVIDIA Tegra 20 DAS (Digital Audio Switch) controller
+
+Required properties:
+- compatible : "nvidia,tegra20-das"
+- reg : Should contain DAS registers location and length
+
+Example:
+
+das@70000c00 {
+	compatible = "nvidia,tegra20-das";
+	reg = <0x70000c00 0x80>;
+};