Don't make a mistake of putting nontrivial control logic onto the same chip as the mining circuitry. In case of failure you won't be able to distinguish between the real fault or bogus fault induced by the noise and/or heat from mining logic. By definition the mining logic has to work at the edge of starvation or hyperthermia death, otherwise it is operating far from optimal.

Helveticoin did something like you are thinking (including an on-die ARM controller) and it was completely non-competitive. It had to be severely underclocked to maintain the reliability of the controlling SoC.

Spondoolies included on-die power-on-self-test and then had to create software workarounds for mining engines that fail the POST but operate correctly after a warm-up. Some desperadoes resorted to preheating their miners with a hair dryer.

You'll be much better off with just temperature-sensing diodes or averaging multiple low-accuracy temperature sensors located in far-away corners of the die.