clk: shmobile: Add new Renesas CPG/MSSR DT bindings

* 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,r8a7795-cpg-mssr" for the r8a7795 SoC

  - 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" (r8a7795)

      - "extalr" (r8a7795)

  - #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.txt.

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>;

	};

  - 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 = "sci_ick";

		dmas = <&dmac1 0x13>, <&dmac1 0x12>;

		dma-names = "tx", "rx";

		power-domains = <&cpg>;

		status = "disabled";

	};

/*

 * Copyright (C) 2015 Renesas Electronics Corp.

 *

 * This program is free software; you can redistribute it and/or modify

 * it under the terms of the GNU General Public License as published by

 * the Free Software Foundation; either version 2 of the License, or

 * (at your option) any later version.

 */

#ifndef __DT_BINDINGS_CLOCK_RENESAS_CPG_MSSR_H__

#define __DT_BINDINGS_CLOCK_RENESAS_CPG_MSSR_H__

#define CPG_CORE			0	/* Core Clock */

#define CPG_MOD				1	/* Module Clock */

#endif /* __DT_BINDINGS_CLOCK_RENESAS_CPG_MSSR_H__ */