dt-bindings: Add bindings for the Amlogic Meson dw-hdmi extension

This binding describes the Amlogic Meson specific extension to the
Synopsys Designware HDMI Controller.
Acked-by: NRob Herring <robh@kernel.org>
Signed-off-by: NNeil Armstrong <narmstrong@baylibre.com>

Documentation/devicetree/bindings/display/amlogic,meson-dw-hdmi.txt

+Amlogic specific extensions to the Synopsys Designware HDMI Controller
+======================================================================
+
+The Amlogic Meson Synopsys Designware Integration is composed of :
+- A Synopsys DesignWare HDMI Controller IP
+- A TOP control block controlling the Clocks and PHY
+- A custom HDMI PHY in order to convert video to TMDS signal
+ ___________________________________
+|            HDMI TOP               |<= HPD
+|___________________________________|
+|                  |                |
+|  Synopsys HDMI   |   HDMI PHY     |=> TMDS
+|    Controller    |________________|
+|___________________________________|<=> DDC
+
+The HDMI TOP block only supports HPD sensing.
+The Synopsys HDMI Controller interrupt is routed through the
+TOP Block interrupt.
+Communication to the TOP Block and the Synopsys HDMI Controller is done
+via a pair of dedicated addr+read/write registers.
+The HDMI PHY is configured by registers in the HHI register block.
+
+Pixel data arrives in 4:4:4 format from the VENC block and the VPU HDMI mux
+selects either the ENCI encoder for the 576i or 480i formats or the ENCP
+encoder for all the other formats including interlaced HD formats.
+
+The VENC uses a DVI encoder on top of the ENCI or ENCP encoders to generate
+DVI timings for the HDMI controller.
+
+Amlogic Meson GXBB, GXL and GXM SoCs families embeds the Synopsys DesignWare
+HDMI TX IP version 2.01a with HDCP and I2C & S/PDIF
+audio source interfaces.
+
+Required properties:
+- compatible: value should be different for each SoC family as :
+	- GXBB (S905) : "amlogic,meson-gxbb-dw-hdmi"
+	- GXL (S905X, S905D) : "amlogic,meson-gxl-dw-hdmi"
+	- GXM (S912) : "amlogic,meson-gxm-dw-hdmi"
+	followed by the common "amlogic,meson-gx-dw-hdmi"
+- reg: Physical base address and length of the controller's registers.
+- interrupts: The HDMI interrupt number
+- clocks, clock-names : must have the phandles to the HDMI iahb and isfr clocks,
+  and the Amlogic Meson venci clocks as described in
+  Documentation/devicetree/bindings/clock/clock-bindings.txt,
+  the clocks are soc specific, the clock-names should be "iahb", "isfr", "venci"
+- resets, resets-names: must have the phandles to the HDMI apb, glue and phy
+  resets as described in :
+  Documentation/devicetree/bindings/reset/reset.txt,
+  the reset-names should be "hdmitx_apb", "hdmitx", "hdmitx_phy"
+
+Required nodes:
+
+The connections to the HDMI ports are modeled using the OF graph
+bindings specified in Documentation/devicetree/bindings/graph.txt.
+
+The following table lists for each supported model the port number
+corresponding to each HDMI output and input.
+
+		Port 0		Port 1
+-----------------------------------------
+ S905 (GXBB)	VENC Input	TMDS Output
+ S905X (GXL)	VENC Input	TMDS Output
+ S905D (GXL)	VENC Input	TMDS Output
+ S912 (GXM)	VENC Input	TMDS Output
+
+Example:
+
+hdmi-connector {
+	compatible = "hdmi-connector";
+	type = "a";
+
+	port {
+		hdmi_connector_in: endpoint {
+			remote-endpoint = <&hdmi_tx_tmds_out>;
+		};
+	};
+};
+
+hdmi_tx: hdmi-tx@c883a000 {
+	compatible = "amlogic,meson-gxbb-dw-hdmi", "amlogic,meson-gx-dw-hdmi";
+	reg = <0x0 0xc883a000 0x0 0x1c>;
+	interrupts = <GIC_SPI 57 IRQ_TYPE_EDGE_RISING>;
+	resets = <&reset RESET_HDMITX_CAPB3>,
+		 <&reset RESET_HDMI_SYSTEM_RESET>,
+		 <&reset RESET_HDMI_TX>;
+	reset-names = "hdmitx_apb", "hdmitx", "hdmitx_phy";
+	clocks = <&clkc CLKID_HDMI_PCLK>,
+		 <&clkc CLKID_CLK81>,
+		 <&clkc CLKID_GCLK_VENCI_INT0>;
+	clock-names = "isfr", "iahb", "venci";
+	#address-cells = <1>;
+	#size-cells = <0>;
+
+	/* VPU VENC Input */
+	hdmi_tx_venc_port: port@0 {
+		reg = <0>;
+
+		hdmi_tx_in: endpoint {
+			remote-endpoint = <&hdmi_tx_out>;
+		};
+	};
+
+	/* TMDS Output */
+	hdmi_tx_tmds_port: port@1 {
+		reg = <1>;
+
+		hdmi_tx_tmds_out: endpoint {
+			remote-endpoint = <&hdmi_connector_in>;
+		};
+	};
+};