BEU <-> HART link added in DTS

[mhtwn]

Related issue:

Type of change: other enhancement

Impact: no functional change

Development Phase:implementation

Release Notes
The CPU section in the generated DTS file will have link to the associated BEU. This should help downstream software flows.

Example of the emitted DTS (updated):

{
...
 model = "SiFive,FU500";
....
 L34: cpus {
 	#address-cells = <1>;
 	#size-cells = <0>;
 	L9: cpu@0 {
 		clock-frequency = <0>;
 		...
                      ...
                      ...
 		device_type = "cpu";
 		....
 		sifive,buserror = <&L8>;
 		....
 	};
 };
 L33: soc {
             ....
             ....
 	L8: bus-error-unit@1700000 {
 		compatible = "sifive,buserror0";
 		interrupt-parent = <&L3>;
 		interrupts = <303>;
 		reg = <0x1700000 0x1000>;
 		reg-names = "control";
 	};
             ....
             ....
  }

[mwachs5]

Can you put an example of the emitted DTS in the PR notes?

[mhtwn]

Can you put an example of the emitted DTS in the PR notes?

Done. (kept only relevant-to-the-PR content)

[mwachs5]

Thank you! I assume in that example <L3> points to the PLIC, for example?

[mhtwn]

Thank you! I assume in that example <L3> points to the PLIC, for example?

Yes, that is right.

[richardxia]

I think it would be more idiomatic and readable to call .toSeq instead of .getOrElse(Nil).

Also, do we actually want to call this sifive,buserror0 or should it just be sifive,buserror?

[bsousi5]

It should be not be "sifive,buserror0", but simply be "sifive,buserror" as the version as described in the compatible string.

[mwachs5]

ok, i suggested the change, but would like @mhtwn to show what the outputted DTS looks like with this change and get @bsousi5 's final approval before approving the PR

[mhtwn]

@mwachs5 its a plain string - it will show up in the dts as is.

[mwachs5]

well i see that string in the DTS above in 2 places. I thought that @bsousi5 was saying in the "compat" he expected it to say sifive,buserror0 but the device type to be sifive,buserror

[mhtwn]

ok, just to not create any confusion, the dts in the release notes (updated above) is how the generated dts looks:

1. In the cpu component listing: buserror0 is now -> buserror
2. Compatible field in the 'bus_error_unit' component still lists sifive_buserror0

[mwachs5]

thanks! @bsousi5 if that looks good to you can you please approve the PR? If that's not enough to make it mergable i will approve it

[bsousi5]

I am good with what @mhtwn commented and shown in the release note above.

[bsousi5]

It seems I don't have the permission to hit the approve button. So @mwachs5, you need to approve.

[daveparry]

I do. So I’ve approved based on your, @richardxia and @mwachs5’s reviews.

[richardxia]

cc @bsousi5 @nategraff-sifive, who should comment on the actual produced DTS.