The only known (non-NDA) documentation on the DSP is the PDF spec sheet. The spec sheet doesn't have detailed programming instructions (that's in the NDA documentation).

But I was hoping that somehow there were already some DSP programming commands in the kernel sources that would point the way, and a few of the memory location numbers from the spec sheet could help you.

I'm having trouble locating the SAA7705H spec sheet on the web at this time, so I'm emailing you my copy right now.