dt-bindings: arm: msm: Rework kpss-gcc driver Documentation to yaml

Rework kpss-gcc driver Documentation to yaml Documentation and move it
to clock as it's a clock-controller.
The current kpss-gcc Documentation have major problems and can't be
converted directly. Introduce various changes to the original
Documentation.

Add #clock-cells additional binding as this clock outputs a static clk
named acpu_l2_aux with supported compatible.
Only some compatible require and outputs a clock, for the others, set
only the reg as a required binding to correctly export the kpss-gcc
registers. As the reg is shared also add the required syscon compatible.

Signed-off-by: Christian Marangi <[e-mail]>
Reviewed-by: Rob Herring <[e-mail]>
Signed-off-by: Bjorn Andersson <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]

Documentation/devicetree/bindings/arm/msm/qcom,kpss-gcc.txt

···
-Krait Processor Sub-system (KPSS) Global Clock Controller (GCC)
-
-PROPERTIES
-
-- compatible:
-	Usage: required
-	Value type: <string>
-	Definition: should be one of the following. The generic compatible
-			"qcom,kpss-gcc" should also be included.
-			"qcom,kpss-gcc-ipq8064", "qcom,kpss-gcc"
-			"qcom,kpss-gcc-apq8064", "qcom,kpss-gcc"
-			"qcom,kpss-gcc-msm8974", "qcom,kpss-gcc"
-			"qcom,kpss-gcc-msm8960", "qcom,kpss-gcc"
-
-- reg:
-	Usage: required
-	Value type: <prop-encoded-array>
-	Definition: base address and size of the register region
-
-- clocks:
-	Usage: required
-	Value type: <prop-encoded-array>
-	Definition: reference to the pll parents.
-
-- clock-names:
-	Usage: required
-	Value type: <stringlist>
-	Definition: must be "pll8_vote", "pxo".
-
-- clock-output-names:
-	Usage: required
-	Value type: <string>
-	Definition: Name of the output clock. Typically acpu_l2_aux indicating
-		    an L2 cache auxiliary clock.
-
-Example:
-
-	l2cc: clock-controller@2011000 {
-		compatible = "qcom,kpss-gcc-ipq8064", "qcom,kpss-gcc";
-		reg = <0x2011000 0x1000>;
-		clocks = <&gcc PLL8_VOTE>, <&gcc PXO_SRC>;
-		clock-names = "pll8_vote", "pxo";
-		clock-output-names = "acpu_l2_aux";
-	};

Documentation/devicetree/bindings/clock/qcom,kpss-gcc.yaml

···
+# SPDX-License-Identifier: GPL-2.0-only OR BSD-2-Clause
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/clock/qcom,kpss-gcc.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Krait Processor Sub-system (KPSS) Global Clock Controller (GCC)
+
+maintainers:
+  - Christian Marangi <[e-mail]>
+
+description:
+  Krait Processor Sub-system (KPSS) Global Clock Controller (GCC). Used
+  to control L2 mux (in the current implementation) and provide access
+  to the kpss-gcc registers.
+
+properties:
+  compatible:
+    items:
+      - enum:
+          - qcom,kpss-gcc-ipq8064
+          - qcom,kpss-gcc-apq8064
+          - qcom,kpss-gcc-msm8974
+          - qcom,kpss-gcc-msm8960
+          - qcom,kpss-gcc-msm8660
+          - qcom,kpss-gcc-mdm9615
+      - const: qcom,kpss-gcc
+      - const: syscon
+
+  reg:
+    maxItems: 1
+
+  clocks:
+    minItems: 2
+    maxItems: 2
+
+  clock-names:
+    items:
+      - const: pll8_vote
+      - const: pxo
+
+  '#clock-cells':
+    const: 0
+
+required:
+  - compatible
+  - reg
+
+if:
+  properties:
+    compatible:
+      contains:
+        enum:
+          - qcom,kpss-gcc-ipq8064
+          - qcom,kpss-gcc-apq8064
+          - qcom,kpss-gcc-msm8974
+          - qcom,kpss-gcc-msm8960
+then:
+  required:
+    - clocks
+    - clock-names
+    - '#clock-cells'
+else:
+  properties:
+    clock: false
+    clock-names: false
+    '#clock-cells': false
+
+additionalProperties: false
+
+examples:
+  - |
+    #include <dt-bindings/clock/qcom,gcc-ipq806x.h>
+
+    clock-controller@2011000 {
+      compatible = "qcom,kpss-gcc-ipq8064", "qcom,kpss-gcc", "syscon";
+      reg = <0x2011000 0x1000>;
+      clocks = <&gcc PLL8_VOTE>, <&pxo_board>;
+      clock-names = "pll8_vote", "pxo";
+      #clock-cells = <0>;
+    };
+
+  - |
+    clock-controller@2011000 {
+      compatible = "qcom,kpss-gcc-mdm9615", "qcom,kpss-gcc", "syscon";
+      reg = <0x02011000 0x1000>;
+    };
+...