Broadcom Power Management Bus (PMB) Driver

The Power Management Bus (PMB) is a dedicated bus within the SoC that is used
to communicate with the Block Power Control Module (BPCM) sub-blocks in the
SoC. There are two variations of the PMB register interface, one using indirect
addressing to the individual BPCM's while the other maps each BPCM directly
into the top level register space. There are also two different versions of the
indirect addressing variation: version 1 has the PMB registers in address order
CFG, CTRL, WR_DATA, RD_DATA, while version 2 has the PMB registers in address
order CTRL, WR_DATA, CFG, RD_DATA.

Required properties:

- compatible:
    Must be "brcm,pmb"

- reg:
    Defines the base and size of the I/O address space of the PMB registers.

- #address-cells:
    Specifies the number of address cells in a BPCM child node's reg property.
    Must be 0.

- #size-cells:
    Specifies the number of size cells in a BPCM child node's reg property.
    Must be 1.

Optional Properties:

- direct-access:
    Indicates that the direct addressing is required for access to the
    BPCM devices on the bus.

- version:
    Must be specified if the direct-access property is missing. This indicates
    the version of indirect addressing register layout exists.

Example:

	pmb@0xd3c03100 {
		compatible = "brcm,pmb";
		reg = <0 0xd3c03100 0 0x50000>;
		#address-cells = <0>;
		#size-cells = <1>;
		direct-access;

		pbcm@0x7 {
			compatible = "brcm,bpcm";
			reg = <0x7>;
			dev-name = "bpcm-fpm";
			zones = <1>;
			boot-on;
		};

		pbcm@0x8 {
			compatible = "brcm,bpcm";
			reg = <0x8>;
			dev-name = "bpcm-cpuc";
			zones = <1>;
			boot-on;
		};

		pbcm@0xb {
			compatible = "brcm,bpcm";
			reg = <0xb>;
			dev-name = "bpcm-unimac";
			zones = <1>;
			boot-on;
		};
	};

	pmb@0xf10b0f00 {
		compatible = "brcm,pmb";
		reg = <0 0xf10b0f00 0 0x10>;
		#address-cells = <0>;
		#size-cells = <1>;
		version=<2>;

		pbcm@0x0 {
			compatible = "brcm,bpcm";
			reg = <0x0>;
			dev-name = "bpcm-rdp";
			zones = <2>;
			boot-on;
		};
	};
