dt-bindings: display: sunxi: add DT binding for Allwinner H6 DW HDMI

The Allwinner H6 SoC uses a v2.12a DesignWare HDMI controller, with
dedicated CEC and HDCP clocks added; the PHY connected is a standard
DesignWare HDMI PHY.

Add binding for it.
Reviewed-by: Rob Herring <robh@kernel.org>
Signed-off-by: Icenowy Zheng <icenowy@aosc.io>
[added HDCP clock and reset]
Signed-off-by: Jernej Skrabec <jernej.skrabec@siol.net>
Signed-off-by: Maxime Ripard <maxime.ripard@bootlin.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20181104182705.18047-19-jernej.skrabec@siol.net

Documentation/devicetree/bindings/display/sunxi/sun4i-drm.txt

@@ -79,6 +79,7 @@ Required properties:
   - compatible: value must be one of:
     * "allwinner,sun8i-a83t-dw-hdmi"
     * "allwinner,sun50i-a64-dw-hdmi", "allwinner,sun8i-a83t-dw-hdmi"
+    * "allwinner,sun50i-h6-dw-hdmi"
   - reg: base address and size of memory-mapped region
   - reg-io-width: See dw_hdmi.txt. Shall be 1.
   - interrupts: HDMI interrupt number
@@ -86,9 +87,14 @@ Required properties:
     * iahb: the HDMI bus clock
     * isfr: the HDMI register clock
     * tmds: TMDS clock
+    * cec: HDMI CEC clock (H6 only)
+    * hdcp: HDCP clock (H6 only)
+    * hdcp-bus: HDCP bus clock (H6 only)
   - clock-names: the clock names mentioned above
-  - resets: phandle to the reset controller
-  - reset-names: must be "ctrl"
+  - resets:
+    * ctrl: HDMI controller reset
+    * hdcp: HDCP reset (H6 only)
+  - reset-names: reset names mentioned above
   - phys: phandle to the DWC HDMI PHY
   - phy-names: must be "phy"
 
@@ -109,6 +115,7 @@ Required properties:
     * allwinner,sun8i-h3-hdmi-phy
     * allwinner,sun8i-r40-hdmi-phy
     * allwinner,sun50i-a64-hdmi-phy
+    * allwinner,sun50i-h6-hdmi-phy
   - reg: base address and size of memory-mapped region
   - clocks: phandles to the clocks feeding the HDMI PHY
     * bus: the HDMI PHY interface clock