On Mon, Feb 15, 2016 at 10:16:50PM +0100, Geert Uytterhoeven wrote:

The Renesas R-Car System Controller provides power management for the
CPU cores and various coprocessors, following the generic PM domain
bindings in Documentation/devicetree/bindings/power/power_domain.txt.

This supports R-Car Gen1, Gen2, and Gen3.

Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
---
Alternatives I considered:

  - Using a single node per power register block, even if it contains
    multiple domains, e.g.:

	    pd_ca15_scu: ca15_scu at 180 {
		    reg = <0x180 0x20>;
		    #address-cells = <1>;
		    #size-cells = <0>;
		    #power-domain-cells = <0>;
		    renesas,interrupt-bits = <12>;

		    pd_ca15_cpu: ca15_cpu at 40 {
			    reg = <0x40 0x20>;
			    #power-domain-cells = <1>;
			    renesas,pm-domain-indices = <0 1>;
			    renesas,pm-domain-names =
				    "ca15_cpu0", "ca15_cpu1";
			    renesas,interrupt-bits = <0 1>;
		    };
	    };

    Notes:
      - You cannot just have a property with the number of domains, as
	index 0 is not used on R-Car H1. Hence the need for
	"renesas,pm-domain-indices" and "renesas,interrupt-bits",
      - "#power-domain-cells = <1>" for nodes with multiple domains,
	which allows typos in "power-domains = <&pd_ca15_cpu n>", using
	an invalid value of "n".

  - Using a linear description in DT:
      - Needs parent links for subdomains,
      - More complicated to parse (lesson learned from R-Mobile PM
	Domain support).

  - Keeping the power register block offset and the bit number as separate
    "reg" cells, increasing "#address-cells" from 2 to 3,

  - Merging the interrupt bit (which needs only 5 bits) in the other "reg"
    cell, decreasing "#address-cells" from 2 to 1.

I think I'd move to not encoding mulitple things into reg. This seems 
like a bit of abuse of reg. Otherwise, I don't have much to comment on.

Rob