Want a means of getting at current hotplug FPGA state

There are some issues that I'm trying to debug where the host seems to think presence is asserted for something that should not be. It's not clear to me right now if this is a Sidecar issue, a cable issue, a Cosmo FPGA issue, or just a classic illumos kernel bug (as my luck usually goes). What would have helped was the ability to read the raw fpga state registers that represent what it thinks it's seeing. That would have helped us bifurcate this a bit.

Start by tracing how hotplug presence state is represented and where the Cosmo FPGA state is accessed. Determine the appropriate entry point for exposing the raw FPGA state registers without assuming whether the issue is in Sidecar, the cable, the FPGA, or illumos. Done means a user can read the relevant raw state needed to distinguish those failure sources.