Support for AP mode requires some control over management frames that hardware sends. This may vary between devices depending on the FullMAC implementation.
Most FullMAC drivers will need to implement following callbacks:
start_ap - to configure hardware to use requested channel and send beacons with provided data
stop_ap - to stop AP mode
del_station - to allow disconnecting client If the hardware is capable of sending/receiving any management frames, you may also need to implement mgmt_tx and mgmt_frame_register.