Hi Tim

Cool. I would say this is done right.

One issue I'm trying to figure out the best way to deal with is the
fact that the GSC can 'NAK' transactions occasionally which is why I
override the regmap read/write functions and provide retries. This
resolves the issue for the mfd core driver and sub-module drivers but
doesn't resolve the issue with these 'emulated devices' which have
their own stand-alone drivers. I'm not sure how to best deal with that
yet. I tried to add retires to the i2c adapter but that wasn't
accepted upstream because it was too generic and I was told I need to
work around it in device-drivers.

How about writing an i2c bus driver which sits directly on top of
another i2c bus? Basically a one port i2c mux.

The current mux code does not seem to directly allow it, since it
calls i2c_transfer() directly on the parent, where as you want it to
call your own i2c_transfer function. But maybe you could expended the
core mux code to allow the i2c_mux_core structure to contain a transfer
function?

      Andrew