[RFC PATCH 1/5] dt-bindings: soundwire: add slave bindings

[Srinivas Kandagatla <srinivas.kandagatla@linaro.org>]

This patch adds bindings for Soundwire Slave devices which includes how
SoundWire enumeration address is represented in SoundWire slave device
tree nodes.

Signed-off-by: Srinivas Kandagatla <srinivas.kandagatla@linaro.org>
---
 .../devicetree/bindings/soundwire/bus.txt     | 48 +++++++++++++++++++
 1 file changed, 48 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/soundwire/bus.txt

diff --git a/Documentation/devicetree/bindings/soundwire/bus.txt b/Documentation/devicetree/bindings/soundwire/bus.txt
new file mode 100644
index 000000000000..19a672b0d528
--- /dev/null
+++ b/Documentation/devicetree/bindings/soundwire/bus.txt
@@ -0,0 +1,48 @@
+SoundWire bus bindings.
+
+SoundWire is a 2-pin multi-drop interface with data and clock line.
+It facilitates development of low cost, efficient, high performance systems.
+
+SoundWire controller bindings are very much specific to vendor.
+
+Child nodes(SLAVE devices):
+Every SoundWire controller node can contain zero or more child nodes
+representing slave devices on the bus. Every SoundWire slave device is
+uniquely determined by the enumeration address containing 5 fields:
+SoundWire Version, Instance ID, Manufacturer ID, Part ID and Class ID
+for a device. Addition to below required properties, child nodes can
+have device specific bindings.
+
+Required property for SoundWire child node if it is present:
+- compatible:	 "sdwVER,MFD,PID,CID". The textual representation of
+		  SoundWire Enumeration address comprising SoundWire
+		  Version, Manufacturer ID, Part ID and Class ID,
+		  shall be in lower-case hexadecimal with leading
+		  zeroes suppressed.
+		  Version number '0x10' represents SoundWire 1.0
+		  Version number '0x11' represents SoundWire 1.1
+		  ex: "sdw10,0217,2010,0"
+
+- sdw-instance-id: Should be ('Instance ID') from SoundWire
+		  Enumeration Address. Instance ID is for the cases
+		  where multiple Devices of the same type or Class
+		  are attached to the bus.
+
+SoundWire example for Qualcomm's SoundWire controller:
+
+soundwire@c2d0000 {
+	compatible = "qcom,soundwire-v1.5.0"
+	reg = <0x0c2d0000 0x2000>;
+
+	spkr_left:wsa8810-left{
+		compatible = "sdw10,0217,2010,0";
+		sdw-instance-id = <1>;
+		...
+	};
+
+	spkr_right:wsa8810-right{
+		compatible = "sdw10,0217,2010,0";
+		sdw-instance-id = <2>;
+		...
+	};
+};
-- 
2.21.0