"chirp" with arbitrary period
If I understand correctly, you are trying to create a chirp an arbitrary instantaneous frequency, $f(t)$.
In that case, the phase of the chirp is given by $\varphi(t) = 2 \pi \int f(t)dt$ and your signal in time domain is given by $s(t) = \sin(\varphi(t))$.
For example, in case of a linear chirp  you mentioned, $f(t) = f_0 + \beta t$ (where $\beta$ is the sweep rate) and therefore $s(t) = \sin \left(2 \pi (f_0 t+\frac{1}{2}\beta t^2) \right)$.