Well to start with you have to have all 120 controllers managed by Airwave and enough Airwave licenses to manage the 120 controllers and all the APs on the controllers. Once you do this it is just a matter of setting up a report definition. They have pre built ones for inventory already you can select from.
Or you can go under "APs and devices" in the gui. Select "List" and then filter based on top folder and expand to show all APs and Devices. Once you have the list up you can export it to a .csv