dt-bindings: arm: amlogic: Add SoC information bindings

Add bindings for the SoC information register of the Amlogic SoCs.
Acked-by: Rob Herring <robh@kernel.org>
Signed-off-by: Neil Armstrong <narmstrong@baylibre.com>
Signed-off-by: Kevin Hilman <khilman@baylibre.com>

Documentation/devicetree/bindings/arm/amlogic.txt

@@ -61,3 +61,32 @@ Board compatible values (alphabetically, grouped by SoC):
   - "amlogic,q201" (Meson gxm s912)
   - "kingnovel,r-box-pro" (Meson gxm S912)
   - "nexbox,a1" (Meson gxm s912)
+
+Amlogic Meson Firmware registers Interface
+------------------------------------------
+
+The Meson SoCs have a register bank with status and data shared with the
+secure firmware.
+
+Required properties:
+ - compatible: For Meson GX SoCs, must be "amlogic,meson-gx-ao-secure", "syscon"
+
+Properties should indentify components of this register interface :
+
+Meson GX SoC Information
+------------------------
+A firmware register encodes the SoC type, package and revision information on
+the Meson GX SoCs.
+If present, the following property should be added :
+
+Optional properties:
+  - amlogic,has-chip-id: If present, the interface gives the current SoC version.
+
+Example
+-------
+
+ao-secure@140 {
+	compatible = "amlogic,meson-gx-ao-secure", "syscon";
+	reg = <0x0 0x140 0x0 0x140>;
+	amlogic,has-chip-id;
+};