Documentation/devicetree/bindings/sound/audio-graph-card.txt

Audio Graph Card:

Audio Graph Card specifies audio DAI connections of SoC <-> codec.
It is based on common bindings for device graphs.
see ${LINUX}/Documentation/devicetree/bindings/graph.txt

Basically, Audio Graph Card property is same as Simple Card.
see ${LINUX}/Documentation/devicetree/bindings/sound/simple-card.txt

Below are same as Simple-Card.

- label
- widgets
- routing
- dai-format
- frame-master
- bitclock-master
- bitclock-inversion
- frame-inversion
- dai-tdm-slot-num
- dai-tdm-slot-width
- clocks / system-clock-frequency

Required properties:

- compatible				: "audio-graph-card";
- dais					: list of CPU DAI port{s}

Optional properties:
- pa-gpios: GPIO used to control external amplifier.

Example: Single DAI case

	sound_card {
		compatible = "audio-graph-card";

		dais = <&cpu_port>;
	};

	dai-controller {
		...
		cpu_port: port {
			cpu_endpoint: endpoint {
				remote-endpoint = <&codec_endpoint>;

				dai-format = "left_j";
				...
			};
		};
	};

	audio-codec {
		...
		port {
			codec_endpoint: endpoint {
				remote-endpoint = <&cpu_endpoint>;
			};
		};
	};

Example: Multi DAI case

	sound-card {
		compatible = "audio-graph-card";

		label = "sound-card";

		dais = <&cpu_port0
			&cpu_port1
			&cpu_port2>;
	};

	audio-codec@0 {
		...
		port {
			codec0_endpoint: endpoint {
				remote-endpoint = <&cpu_endpoint0>;
			};
		};
	};

	audio-codec@1 {
		...
		port {
			codec1_endpoint: endpoint {
				remote-endpoint = <&cpu_endpoint1>;
			};
		};
	};

	audio-codec@2 {
		...
		port {
			codec2_endpoint: endpoint {
				remote-endpoint = <&cpu_endpoint2>;
			};
		};
	};

	dai-controller {
		...
		ports {
			cpu_port0: port@0 {
				cpu_endpoint0: endpoint {
					remote-endpoint = <&codec0_endpoint>;

					dai-format = "left_j";
					...
				};
			};
			cpu_port1: port@1 {
				cpu_endpoint1: endpoint {
					remote-endpoint = <&codec1_endpoint>;

					dai-format = "i2s";
					...
				};
			};
			cpu_port2: port@2 {
				cpu_endpoint2: endpoint {
					remote-endpoint = <&codec2_endpoint>;

					dai-format = "i2s";
					...
				};
			};
		};
	};