+++ b/Documentation/devicetree/bindings/soundwire/slave.txt @@ -0,0 +1,46 @@ +SoundWire slave device 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 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.
In case the controller supports multiple links, what's the encoding then? in the MIPI DisCo spec there is a linkId field in the _ADR encoding that helps identify which link the Slave device is connected to
+Required property for SoundWire child node if it is present: +- compatible: "sdwVER,MFD,PID,CID". The textual representation of
SoundWire Enumeration address comprising SoundWireVersion, Manufacturer ID, Part ID and Class ID,shall be in lower-case hexadecimal with leadingzeroes suppressed.Version number '0x10' represents SoundWire 1.0Version number '0x11' represents SoundWire 1.1ex: "sdw10,0217,2010,0"+- sdw-instance-id: Should be ('Instance ID') from SoundWire
Enumeration Address. Instance ID is for the caseswhere multiple Devices of the same type or Classare attached to the bus.
so it is actually required if you have a single Slave device? Or is it only required when you have more than 1 device of the same type?
FWIW in the MIPI DisCo spec we kept the instanceID as part of the _ADR, so it's implicitly mandatory (and ignored by the bus if there is only one device of the same time)
+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>;
Isn't the MIPI encoding reported in the Dev_ID0..5 registers 0-based?
...- };
+};
And now that I think of it, wouldn't it be simpler for everyone if we aligned on that MIPI DisCo public spec? e.g. you'd have one property with a 64-bit number that follows the MIPI spec. No special encoding necessary for device tree cases, your DT blob would use this:
soundwire@c2d0000 { compatible = "qcom,soundwire-v1.5.0" reg = <0x0c2d0000 0x2000>;
spkr_left:wsa8810-left{ compatible = "sdw0000100217201000" }
spkr_right:wsa8810-right{ compatible = "sdw0000100217201100" } }
We could use parentheses if it makes people happier, but the information from the MIPI DisCo spec can be used as is, and provide a means for spec changes via reserved bits.