dt-bindings: soc: amlogic: document System Control registers

Document the System Control registers regions found on all Amlogic
SoC families and it's clock, power, pinctrl and phy subnodes.

The regions has various independent registers tied to other
hardware devices, thus the syscon compatible.
Reviewed-by: Rob Herring <robh@kernel.org>
Signed-off-by: Neil Armstrong <neil.armstrong@linaro.org>
Link: https://lore.kernel.org/r/20230706-b4-amlogic-bindings-convert-take2-v3-3-f63de6f12dcc@linaro.orgSigned-off-by: Jerome Brunet <jbrunet@baylibre.com>

Documentation/devicetree/bindings/soc/amlogic/amlogic,meson-gx-hhi-sysctrl.yaml

+# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/soc/amlogic/amlogic,meson-gx-hhi-sysctrl.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Amlogic Meson System Control registers
+
+maintainers:
+  - Neil Armstrong <neil.armstrong@linaro.org>
+
+properties:
+  compatible:
+    items:
+      - enum:
+          - amlogic,meson-gx-hhi-sysctrl
+          - amlogic,meson-gx-ao-sysctrl
+          - amlogic,meson-axg-hhi-sysctrl
+          - amlogic,meson-axg-ao-sysctrl
+      - const: simple-mfd
+      - const: syscon
+
+  reg:
+    maxItems: 1
+
+  clock-controller:
+    type: object
+
+  power-controller:
+    $ref: /schemas/power/amlogic,meson-ee-pwrc.yaml
+
+  pinctrl:
+    type: object
+
+  phy:
+    type: object
+
+allOf:
+  - if:
+      properties:
+        compatible:
+          enum:
+            - amlogic,meson-gx-hhi-sysctrl
+            - amlogic,meson-axg-hhi-sysctrl
+    then:
+      properties:
+        clock-controller:
+          $ref: /schemas/clock/amlogic,gxbb-clkc.yaml#
+
+      required:
+        - power-controller
+
+  - if:
+      properties:
+        compatible:
+          enum:
+            - amlogic,meson-gx-ao-sysctrl
+            - amlogic,meson-axg-ao-sysctrl
+    then:
+      properties:
+        clock-controller:
+          $ref: /schemas/clock/amlogic,gxbb-aoclkc.yaml#
+
+        power-controller: false
+        phy: false
+
+  - if:
+      properties:
+        compatible:
+          enum:
+            - amlogic,meson-gx-hhi-sysctrl
+    then:
+      properties:
+        phy: false
+
+  - if:
+      properties:
+        compatible:
+          enum:
+            - amlogic,meson-axg-hhi-sysctrl
+    then:
+      properties:
+        phy:
+          oneOf:
+            - $ref: /schemas/phy/amlogic,g12a-mipi-dphy-analog.yaml
+            - $ref: /schemas/phy/amlogic,meson-axg-mipi-pcie-analog.yaml
+
+required:
+  - compatible
+  - reg
+  - clock-controller
+
+additionalProperties: false
+
+examples:
+  - |
+    bus@c883c000 {
+        compatible = "simple-bus";
+        reg = <0xc883c000 0x2000>;
+        #address-cells = <1>;
+        #size-cells = <1>;
+        ranges = <0x0 0xc883c000 0x2000>;
+
+        sysctrl: system-controller@0 {
+            compatible = "amlogic,meson-gx-hhi-sysctrl", "simple-mfd", "syscon";
+            reg = <0 0x400>;
+
+            clock-controller {
+                compatible = "amlogic,gxbb-clkc";
+                #clock-cells = <1>;
+                clocks = <&xtal>;
+                clock-names = "xtal";
+            };
+
+            power-controller {
+                compatible = "amlogic,meson-gxbb-pwrc";
+                #power-domain-cells = <1>;
+                amlogic,ao-sysctrl = <&sysctrl_AO>;
+
+                resets = <&reset_viu>,
+                         <&reset_venc>,
+                         <&reset_vcbus>,
+                         <&reset_bt656>,
+                         <&reset_dvin>,
+                         <&reset_rdma>,
+                         <&reset_venci>,
+                         <&reset_vencp>,
+                         <&reset_vdac>,
+                         <&reset_vdi6>,
+                         <&reset_vencl>,
+                         <&reset_vid_lock>;
+                reset-names = "viu", "venc", "vcbus", "bt656", "dvin",
+                              "rdma", "venci", "vencp", "vdac", "vdi6",
+                              "vencl", "vid_lock";
+                clocks = <&clk_vpu>, <&clk_vapb>;
+                clock-names = "vpu", "vapb";
+            };
+        };
+    };
+
+    bus@c8100000 {
+        compatible = "simple-bus";
+        reg = <0xc8100000 0x100000>;
+        #address-cells = <1>;
+        #size-cells = <1>;
+        ranges = <0x0 0xc8100000 0x100000>;
+
+        sysctrl_AO: system-controller@0 {
+            compatible = "amlogic,meson-gx-ao-sysctrl", "simple-mfd", "syscon";
+            reg = <0 0x100>;
+
+            clock-controller {
+                compatible = "amlogic,meson-gxbb-aoclkc", "amlogic,meson-gx-aoclkc";
+                #clock-cells = <1>;
+                #reset-cells = <1>;
+                clocks = <&xtal>, <&clk81>;
+                clock-names = "xtal", "mpeg-clk";
+            };
+        };
+    };