Re: [PATCHv3 34/35] ARM: dts: dra7: add system control module node

[Tony Lindgren <tony@atomide.com>]

* Tero Kristo <t-kristo@ti.com> [150311 12:09]:
> On 03/11/2015 07:17 PM, Tony Lindgren wrote:
> >Hi Tero,
> >
> >* Tero Kristo <t-kristo@ti.com> [150225 11:09]:
> >>Add node for system control module, and move all the existing system
> >>control IO space users under this new node as its children. A new node
> >>for scm_conf area is also added.
> >...
> >
> >>--- a/arch/arm/boot/dts/dra7.dtsi
> >>+++ b/arch/arm/boot/dts/dra7.dtsi
> >>@@ -203,26 +203,47 @@
> >>  			};
> >>  		};
> >>
> >>+		scm: scm@4a002000 {
> >>+			compatible = "ti,dra7-ctrl", "simple-bus";
> >>+			reg = <0x4a002000 0x1400>,
> >>+			      <0x4a003400 0x600>,
> >>+			      <0x4ae0c000 0x600>;
> >>+			#address-cells = <2>;
> >>+			#size-cells = <1>;
> >>+			ranges = <0 0 0x4a002000 0x1400>,
> >>+				 <1 0 0x4a003400 0x600>,
> >>+				 <2 0 0x4ae0c000 0x600>;
> >>+
> >>+			scm_conf: tisyscon@0,0 {
> >>+				compatible = "syscon";
> >>+				reg = <0 0x0 0x1400>;
> >>+				#address-cells = <1>;
> >>+				#size-cells = <1>;
> >>+			};
> >>+
> >>+			dra7_pmx_core: pinmux@1,0 {
> >>+				compatible = "ti,dra7-padconf",
> >>+					     "pinctrl-single";
> >>+				reg = <1 0x0 0x0464>;
> >>+				#address-cells = <1>;
> >>+				#size-cells = <0>;
> >>+				#interrupt-cells = <1>;
> >>+				interrupt-controller;
> >>+				pinctrl-single,register-width = <32>;
> >>+				pinctrl-single,function-mask = <0x3fffffff>;
> >>+			};
> >>+		};
> >
> >Wouldn't it make more sense to have separate device_scm, core_scm and
> >wkup_scm instead of stuffing multiple ranges here?
> >
> >Or are there other reasons for the multiple ranges?
> 
> Yea that was the alternative I was thinking about, I ended up with this for
> some reason. I think personally I liked having them all under the same SCM
> part, because they are nicely grouped then, and well, its the same system
> control part in the chip. We can split it up easily of course. Should we
> have a higher level scm part and then have core_scm and wkup_scm under this
> followed by the sub-functions, or just drop the top level scm part
> completely?

Well I'd model it after the hardware so we can have one or more scm driver
instances managing the clock for those blocks. If we squash them together,
we won't have a chance to pass interrupts and clocks device tree property
to the right driver instance. And for example 5432 TRM has them as separate
devices in "Figure 18-1. Control Module Overview".

I don't think we need the top level scm to group them under, these are all
connected seprately to the interconnect, right?
 
> This same question applies to omap4 + omap5 also. In some part for omap3
> also, as it also has pmx_core + pmx_wkup separately, even if they are part
> of the same register space.
> 
> Anyway, just a political decision from your side, I am fine either way. :)

OK thanks for confirming that, to me it makes sense to set them up as
separate instances then.

Regards,

Tony