Single wire can bus and bidirectional pin coding

I have another question, unrelated to bidirectional ports.

my device has a set of registers, which can be written by an external SPI interface, as well as user logic.

This will result in multiple drivers for the registers, driven by the SPI slave process, and the user logic process.

Two methods that I have thought of to resolve this:

1. Use a true dual port RAM, and do read writes from the RAM.

2. inplement a signal on the SPI logic, which the User logic will read and update the register.

I am more in favor of 1 , as it looks like a more modular implementation but i will need to watch out for write contentions and the two clock cycles to read the registers.

Are there any generic methods (better method) to resolve this?