dt-bindings: clk: mstar msc313 cpupll binding description

Add a binding description for the MStar/SigmaStar CPU PLL block.
Signed-off-by: NDaniel Palmer <daniel@0x0f.com>
Reviewed-by: NRob Herring <robh@kernel.org>

Documentation/devicetree/bindings/clock/mstar,msc313-cpupll.yaml

+# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/clock/mstar,msc313-cpupll.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: MStar/Sigmastar MSC313 CPU PLL
+
+maintainers:
+  - Daniel Palmer <daniel@thingy.jp>
+
+description: |
+  The MStar/SigmaStar MSC313 and later ARMv7 chips have a scalable
+  PLL that can be used as the clock source for the CPU(s).
+
+properties:
+  compatible:
+    const: mstar,msc313-cpupll
+
+  "#clock-cells":
+    const: 1
+
+  clocks:
+    maxItems: 1
+
+  reg:
+    maxItems: 1
+
+required:
+  - compatible
+  - "#clock-cells"
+  - clocks
+  - reg
+
+additionalProperties: false
+
+examples:
+  - |
+    #include <dt-bindings/clock/mstar-msc313-mpll.h>
+    cpupll: cpupll@206400 {
+        compatible = "mstar,msc313-cpupll";
+        reg = <0x206400 0x200>;
+        #clock-cells = <1>;
+        clocks = <&mpll MSTAR_MSC313_MPLL_DIV2>;
+    };