ASoC: Add ssm2518 support

This patch adds a ASoC CODEC driver for the SSM2516. The SSM2516 is a stereo
Class-D audio amplifier with an I2S interface for audio in and a built-in
dynamic range control processor.

Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
diff --git a/Documentation/devicetree/bindings/sound/ssm2518.txt b/Documentation/devicetree/bindings/sound/ssm2518.txt
new file mode 100644
index 0000000..59381a7
--- /dev/null
+++ b/Documentation/devicetree/bindings/sound/ssm2518.txt
@@ -0,0 +1,20 @@
+SSM2518 audio amplifier
+
+This device supports I2C only.
+
+Required properties:
+  - compatible : Must be "adi,ssm2518"
+  - reg : the I2C address of the device. This will either be 0x34 (ADDR pin low)
+	or 0x35 (ADDR pin high)
+
+Optional properties:
+  - gpios : GPIO connected to the nSD pin. If the property is not present it is
+	        assumed that the nSD pin is hardwired to always on.
+
+Example:
+
+	ssm2518: ssm2518@34 {
+		compatible = "adi,ssm2518";
+		reg = <0x34>;
+		gpios = <&gpio 5 0>;
+	};