On Wed, Mar 24, 2021 at 02:30:35PM -0700, Dan Williams wrote:

In preparation for common register mapping facility, introduce a generic
container, 'struct cxl_regs', for CXL device register and later
component register block base pointers. Some CXL device types implement
both.

The code looks like complete gibberish to me with a struct of a union of
a struct declaring members in a macro.  This needs a much more detailed
explanation and rationale.