T3's SD controller is as good as undocumented since no information on it can be obtained easily.
Most information on the 'net about is either useless(the public spec. sheet) or wrong(the palm Linux project driver). So I went on to figure out how it works. The original driver only uses part of the functionality, but I am determined to get it to work completely. So far I mostly figured out the command/response related registers, and the response FIFO. The data FIFO is still not working too well, but it will soon.
The cool part about this chip is that the FIFO shows how many bytes are in it, unlike other CPUs, where you just get a full/not full bit.