Not quite; the tuner module does *all* the tuning (front end, IF mix, demod etc etc). The DSP just does baseband signal processing (weak signal processing, inteference supression, etc), RDS extraction and FM demultiplex.

The tuner module itself is handed a frequency and various other settings and gives you the demodulated AF L+R/L-R/RDS signal over one wire and an analogue indication of signal strength over another.

There is an I2C eeprom in the tuner module which contains calibration values which are used (with interpolation) to calibrate signal strength indications over the entire tuning range.

Hugo