AreYouLoco, I am really glad to see there is someone else who is interested in this. If necessary, I will provide the coreboot config in a few hours, but it was nothing special.
It was built from master and I have simply selected mainboard vendor/model, checked Use CMOS for configuration values and increased Size of CBFS up to 0x300000.

In the meanwhile, here's my only lspci entry related to Ricoh: https://del.dog/lspci_ricoh_coreboot.txt

I believe that src/mainboard/lenovo/t420/devicetree.cb (around line 85) has a statement related to that controller, but I will have to take a closer look at the coreboot source-code.

device pci 1c.4 on
        chip drivers/ricoh/rce822
                register "sdwppol" = "1"
                register "disable_mask" = "0x87"
                device pci 00.0 on end
        end
end # PCIe Port #5 (Ricoh SD & FW)

On Wed, Apr 8, 2020 at 1:05 PM AreYouLoco? <areyouloco@paranoici.org> wrote:
On stock latest firmware and ubuntu studio I do see this:
https://del.dog/raw/firewire_lspci

I just builded coreboot. Backing up stock and trying to see if it's detected with coreboot.

Fingers crossed!

On April 8, 2020 9:15:22 AM UTC, Paul Menzel <pmenzel@molgen.mpg.de> wrote:
>Dear AreYouLoco,
>
>
>Am 08.04.20 um 10:59 schrieb AreYouLoco?:
>
>> I am in the same situation. Same board and same controller. Still
>> didn't flash coreboot but I also want to make FW work with coreboot.
>> Could you please share your coreboot build config? Did you build
>> master repo?
>>
>> Thanks. I am also willing to test images and configs to make that
>> setup work.
>
>So, as you still running the vendor firmware, does this setup,
>especially the FireWire/USB controller (40GAB5809-G200), work with the
>vendor firmware? If so, please share the Linux messages and attach the
>output of `sudo lspci -vvxxx`.
>
>
>Kind regards,
>
>Paul
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