Re-work operating modes
Currently, there is only single bit which enables operation of CTU CAN FD (SETTINGS[ENA]). All modes (ROM, LOM, STM, etc...) are handled by dedicated bits in MODE register, and the protection of these bits is added to disallow their change during run-time.
It would be better, to have operating mode FSM, which would be communicating with protocol control FSM, and have this FSM-state (device operating mode) exposed to user.
Right now it is unclear what is the behavior if multiple special modes are combined together.
It still needs to be re-though what will be the granularity of operating modes of the device.