Configuration for NAND Flash is required in three places: one CDL for the specific type of NAND Flash chip; one CDL for the specific type of NAND Flash controller; and one CDL for the target's board that binds all configuration together.
See the CDL file under packages/devs/flash/st-micro/nand0xG as an example. Configuration of some parameters (like minimal width of the read and write pulses) can be done in the CDL file, or it can be done in the source file.