The ROMs we have for sil3112 do have Mac OS 9 and OS X drivers. For OS 9, it's an ndrv. For OS X, it's an mkext. You can get the hex for these from ioreg if you have a working sil3112. Convert the ndrv to an extension for OS 9. Extract the kexts from the mkext for OS X. I don't know if the kext and ndrv will be compatible with a cardbus version of the sil3112.
If you want to boot from the card without a ROM, then OF can probably be patched to load the ROM from a built-in disk. Even if you don't want to boot from it, it might be preferable to have OF load the driver into RAM instead of having to install the ndrv or kext.
The attached are from Feb 3, 2023. I don't know if any changes were made by @dosdude1 to these binaries or if all the changes were made only to the fcode or if any changes were made to these binaries afterward. You don't need the mkext. The kexts are extracted from the mkext using
mkextunpack
. The kext should be pretty easy to install. The ndrv might need some work to make Mac OS 9 load it (type? creator? cfrg resource? init?). Maybe see
#351 ->
#366