* Renesas Clock Pulse Generator / Module Standby and Software Reset

On Renesas ARM SoCs (SH/R-Mobile, R-Car, RZ), the CPG (Clock Pulse Generator)
and MSSR (Module Standby and Software Reset) blocks are intimately connected,
and share the same register block.

They provide the following functionalities:
  - The CPG block generates various core clocks,
  - The MSSR block provides two functions:
      1. Module Standby, providing a Clock Domain to control the clock supply
	 to individual SoC devices,
      2. Reset Control, to perform a software reset of individual SoC devices.

Required Properties:
  - compatible: Must be one of:
      - "renesas,r7s9210-cpg-mssr" for the r7s9210 SoC (RZ/A2)
      - "renesas,r8a7743-cpg-mssr" for the r8a7743 SoC (RZ/G1M)
      - "renesas,r8a7744-cpg-mssr" for the r8a7744 SoC (RZ/G1N)
      - "renesas,r8a7745-cpg-mssr" for the r8a7745 SoC (RZ/G1E)
      - "renesas,r8a77470-cpg-mssr" for the r8a77470 SoC (RZ/G1C)
      - "renesas,r8a774a1-cpg-mssr" for the r8a774a1 SoC (RZ/G2M)
      - "renesas,r8a774b1-cpg-mssr" for the r8a774a1 SoC (RZ/G2N)
      - "renesas,r8a774c0-cpg-mssr" for the r8a774c0 SoC (RZ/G2E)
      - "renesas,r8a7790-cpg-mssr" for the r8a7790 SoC (R-Car H2)
      - "renesas,r8a7791-cpg-mssr" for the r8a7791 SoC (R-Car M2-W)
      - "renesas,r8a7792-cpg-mssr" for the r8a7792 SoC (R-Car V2H)
      - "renesas,r8a7793-cpg-mssr" for the r8a7793 SoC (R-Car M2-N)
      - "renesas,r8a7794-cpg-mssr" for the r8a7794 SoC (R-Car E2)
      - "renesas,r8a7795-cpg-mssr" for the r8a7795 SoC (R-Car H3)
      - "renesas,r8a7796-cpg-mssr" for the r8a77960 SoC (R-Car M3-W)
      - "renesas,r8a77961-cpg-mssr" for the r8a77961 SoC (R-Car M3-W+)
      - "renesas,r8a77965-cpg-mssr" for the r8a77965 SoC (R-Car M3-N)
      - "renesas,r8a77970-cpg-mssr" for the r8a77970 SoC (R-Car V3M)
      - "renesas,r8a77980-cpg-mssr" for the r8a77980 SoC (R-Car V3H)
      - "renesas,r8a77990-cpg-mssr" for the r8a77990 SoC (R-Car E3)
      - "renesas,r8a77995-cpg-mssr" for the r8a77995 SoC (R-Car D3)

  - reg: Base address and length of the memory resource used by the CPG/MSSR
    block

  - clocks: References to external parent clocks, one entry for each entry in
    clock-names
  - clock-names: List of external parent clock names. Valid names are:
      - "extal" (r7s9210, r8a7743, r8a7744, r8a7745, r8a77470, r8a774a1,
		 r8a774b1, r8a774c0, r8a7790, r8a7791, r8a7792, r8a7793,
		 r8a7794, r8a7795, r8a77960, r8a77961, r8a77965, r8a77970,
		 r8a77980, r8a77990, r8a77995)
      - "extalr" (r8a774a1, r8a774b1, r8a7795, r8a77960, r8a77961, r8a77965,
		  r8a77970, r8a77980)
      - "usb_extal" (r8a7743, r8a7744, r8a7745, r8a77470, r8a7790, r8a7791,
		     r8a7793, r8a7794)

  - #clock-cells: Must be 2
      - For CPG core clocks, the two clock specifier cells must be "CPG_CORE"
	and a core clock reference, as defined in
	<dt-bindings/clock/*-cpg-mssr.h>.
      - For module clocks, the two clock specifier cells must be "CPG_MOD" and
	a module number, as defined in the datasheet.

  - #power-domain-cells: Must be 0
      - SoC devices that are part of the CPG/MSSR Clock Domain and can be
	power-managed through Module Standby should refer to the CPG device
	node in their "power-domains" property, as documented by the generic PM
	Domain bindings in
	Documentation/devicetree/bindings/power/power-domain.yaml.

  - #reset-cells: Must be 1
      - The single reset specifier cell must be the module number, as defined
	in the datasheet.


Examples
--------

  - CPG device node:

	cpg: clock-controller@e6150000 {
		compatible = "renesas,r8a7795-cpg-mssr";
		reg = <0 0xe6150000 0 0x1000>;
		clocks = <&extal_clk>, <&extalr_clk>;
		clock-names = "extal", "extalr";
		#clock-cells = <2>;
		#power-domain-cells = <0>;
		#reset-cells = <1>;
	};


  - CPG/MSSR Clock Domain member device node:

	scif2: serial@e6e88000 {
		compatible = "renesas,scif-r8a7795", "renesas,scif";
		reg = <0 0xe6e88000 0 64>;
		interrupts = <GIC_SPI 164 IRQ_TYPE_LEVEL_HIGH>;
		clocks = <&cpg CPG_MOD 310>;
		clock-names = "fck";
		dmas = <&dmac1 0x13>, <&dmac1 0x12>;
		dma-names = "tx", "rx";
		power-domains = <&cpg>;
		resets = <&cpg 310>;
	};