@invzim I can't remember if I pinged you in my force feedback experimentation thread, but if you wanted to work in some force feedback support for the driving games, I'm willing to help.
I believe it will be more of a software requirement, because the hardware *should* be able to be managed off of your board.
Namco games (Mario Karts and WMMTs 1, 2, and 3) use a protocol over RS-232 which would be easy enough to manage through a USB adapter on the RPi. I've got a pretty good grasp of this protocol. JVS output 1-1, just like what is used for start for lamps in many games, is used in these NAMCO games to establish communication with the FFB board, but you should already be able to tap into that through your existing JVS communication management.
Some NAOMI, Triforce and Chihiro games utilize the MIDI FFB and it is completely managed outside of JVS and would require a 2-way MIDI interface, however I don't know if that can be easily done with a USB MIDI adapter. Basically it would need to be accessible as a normal serial port. I wasn't able to make a MIDI adapter work in Windows, and ended up wiring up something with an Arduino. Perhaps you could interface with an Arduino over USB as a serial port and manage the MIDI communication that way? I have a rudimentary understanding of this protocol. I've at least figured out how to drive a MIDI board, even if I can't decipher all of the commands I've seen in logs.
The Lindbergh and newer are also over RS-232. It's a very similar protocol to the MIDI one, but there seem to be slight differences that I hope to figure out when I get a board to analyze.
Your software challenge would be to support these various serial interfaces and to also interface with a USB steering wheel that has FFB. I don't really know anything about PC steering wheels at the moment, but maybe the FFB is driven over HID? So assuming the USB wheel can be effectively driven, then it's a matter of translating the various protocols into something usable.
I'm not suggesting that any of this would be easy by any means, but it would be pretty cool. I'm in the process now of developing an Arduino-based translator that lets me play the other standards on the MIDI FFB and have the NAMCO portion of it working pretty well.
Anyway, this isn't a push from me or anything, just an offer. I don't particularly need this, but think others might find value in it. In my opinion if a game supports FFB, then you should be playing it with FFB.