The taco has an fpga that controls the fan. It must be feed the current 
temperature from an ad7414 chip. This patch adds a patched ad7414 temp 
sensor from the ppc arch and adds a small driver (taco-dtm) to read the 
temperature and feed it to the fpga.

Without this driver, the taco will just run the fan at high speed all 
the time. I don't even know if this is a problem since cases for the 
taco are very rare and I don't have one. I have never actually heard the 
fan running in a case. Although I did see an early version of the fan 
spin up and spin down.

Cheers,
   Sean