Driver Design Question

[Johannes Thumshirn <johannes.thumshirn@men.de>]

Hi List,

I have a design question concerning a device driver. The device in question is
somewhere in between drivers/mfd/timberdale and drivers/ssb. It is mapped
connected via PCI and on PCI Bar 0 there is a table describing which
"sub-devices" are contained in the FPGA as well as where their Memory and IRQ
resources are.

Unlike the timberdale driver, there is no static configuration of the FPGA's
sub-devices, but their number and kind is variable. But luckily we have unique
device-ids for every sub-device, so it is possible to do a PCI/USB like
enumeration.

In my understanding the MFD API, which timberdale uses, isn't tailored to this
Plug'n'Play like behavior. Whereas the I think (virtual) bus concept used by
SSB is much more suited for this kind of devices. But would it be wise to add a
bus only suited to devices manufactured by one vendor, when there is already a
API for such kinds of multi function devices?

Long story short, which would be the preferred way to implement such a driver? At
the point I currently reached I could go in both directions.

I'd appreciate any advice I can get on this topic.

Thanks in advance,

       Johannes

P.S.: MFD and SSB maintainers are on CC as I'd really like to hear their opinion