Question about MFD devices.

Hi! I'm trying to do a simple driver on an embedded (ARM) system that needs to access some functionality in an MFD device. I've deducted that my driver needs to be integrated into the MFD device structure, otherwise I won't really be able to access the required functions. I've been trying to figure out why we have these MFD devices, but I don't see the logic behind them. To me, they mailny seem to duplicate the standard kernel driver structure, and it doesn't seem like the provided functionality should be used in-kernel. I guess that my conclusion are way wrong, so I hope that someone on the list can enlighten me about this. BRs, /Jocke!