A320 pilot reported a flight control unit failure during cruise which resulted limited ability to program the modes on the FCU (Flight Control Unit). The pilot diverted the aircraft and landed safely.

Narrative

Cruising at FL350 approximately 70 miles to ZZZZZ intersection the autopilot captured an ILS signal and started to turn off course. When I tried to pull the HDG knob the aircraft did not respond. I disconnected the autopilot to turn the plane back on course. This is when we noticed we could not select any speed; heading or altitude on the FCP (Flight Control Panel). We disconnected the auto thrust as well to manage speed. We could not set altimeters; select flight directors on or off or deselect FPV to which the aircraft had reverted. At this point we determined that we would need to fly the plane using raw data and manual thrust. CA (Captain) was flying pilot so elected to ask ATC for headings and altitudes while the FO (First Officer) made a call to Maintenance Control. Maintenance Control declared that they see an FCU 2 failure and had us try to reset in flight. This was unsuccessful. At this point we switched controls to the FO and CA notified dispatch and ATC that we would be diverting to ZZZ. We requested priority ATC handling. We landed in ZZZ under visual flight conditions without incident. Upon landing in ZZZ CA was immediately met by supervisors and asked to take a phone call in the jetbridge from operations regarding the nature of the diversion. About 2 minutes after that call system operations called the CAs cell phone requesting the same information. CA then saw 3 Maintenance Control personnel and was asked You diverted for an altitude discrepancy!?" CA then explained the entirety of the failure to tech ops in the jet bridge. This led to the CA getting distracted and neglecting to write a discrepancy in the aircraft logbook. The discrepancy would have read that at cruise FL350 FCP failed. Unable to use FD; HDG; V/S; FPV; ALT; SPEED knobs and buttons. Only FO altimeter could be changed. AUTO FLT FCU 2 caution message was briefly displayed."