I came across this on kt: http://kt.tux.org/kernel-traffic/kt20030805_226.html#3
GPL drivers for PDC20318, PDC20375, PDC20378 and PDC20618.
Hopefully some of this will make it in the kernel soon. I tried compiling the drivers on my SuSE 8.2 system (stock SuSE 2.4.20 kernel) but I get "no valid card found" on boot... (using the precompiled module for now). Using an other kernel doesn't work for me, as you need to be running the same kernel as you are compiling for and I have no other harddisc to use.
Still, this looks very promising and we'll hopefully soon have support for these cards out of the box.