AMD FHC for G-series SOCs (GX-412TC)

[Enrico Weigelt, metux IT consult]

Hi folks,

I'm currently writing Linux drivers for AMD FCH GPIO. It's currently
running fine on an APUv2 board (based on some examples I've found in
the net, including coreboot APUv2 code) but for mainline it should be
more generic. Yet lacking automatic probing / configuration (don't
like hardcoding so much)

My problem now is finding out which FCH it is exactly and find the
corresponding specs. There seem to be two FCH types: Bolton and
hudson.

For Bolton, I've found some specs that seem to fit, but other sites
indicate, the GX-412TC had an Hudson - unfortunately didn't find
any register specs for this one yet.

Does anybody here have some more detailed information on that ?

--thx

[Kyösti Mälkki]

On Mon, Feb 11, 2019 at 12:34 PM Enrico Weigelt, metux IT consult <
[e-mail]> wrote:
> Hi folks,
>
> I'm currently writing Linux drivers for AMD FCH GPIO. It's currently
> running fine on an APUv2 board (based on some examples I've found in
> the net, including coreboot APUv2 code) but for mainline it should be
> more generic. Yet lacking automatic probing / configuration (don't
> like hardcoding so much)
>
> My problem now is finding out which FCH it is exactly and find the
> corresponding specs. There seem to be two FCH types: Bolton and
> hudson.

And Yangtze, Avalon, Kern, ...
> For Bolton, I've found some specs that seem to fit, but other sites
> indicate, the GX-412TC had an Hudson - unfortunately didn't find
> any register specs for this one yet

Well coreboot tree has these names somewhat wrong, and mostly just call
them Hudson. In GX-412TC codename was probably Avalon.
> Does anybody here have some more detailed information on that ?

Usually, AMD BKDG papers have the info you are after, for pcengines/apu2
variants:
https://www.amd.com/system/files/TechDocs/52740_16h_Models_30h-3Fh_BKDG.pdf
https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=2&cad=rja&uact=8&ved=2ahUKEwipkNGKwLPgAhVGUZoKHepUBv8QFjABegQIAxAC&url=https%3A%2F%2Fwww.amd.com%2Fsystem%2Ffiles%2FTechDocs%2F52740_16h_Models_30h-3Fh_BKDG.pdf&usg=AOvVaw0OHMcKQWVAQkya7W-FCnPQ

Often it was PCI 0:14.3 (LPC bridge) register 08h (REVISION_ID) you can
identify FCH silicon from.

HTH,
Kyösti