Hello gumstix list!
Hopefully some kind sole can  help me.
My goal is to connect a serial ADC to McBSP3. It must be a McBSP (and not McSPI) so we can use the sample rate generator to run the sample clock. I've got an overo water and a chestnut board. My question is what is the best way to go about writing the code. I see I can either write a driver that interfaces to the McBSP library in the kernel, or add the ADC into the ALSA framework. Initially I thought adding to the ALSA framework would be the easier task, but as a hardware engineer I quickly got lost in the layers of abstraction and could not figure it out. So I tried writing a simple char driver wrapper for the McBSP library. Am I correct in thinking the steps to get this all working are to request the bsp, stop the bsp, configure it, then issue a mcbsp start, at which point I can call things like omap_mcbsp_xmit_word? Thats what my code currently does but it hangs at the "wait_for_completion" line in the xmid_word code.

I realize seeing my driver code would help, but I wanted to get to the root question first. Is writing a simple char driver to DMA my raw adc data into a userspace buffer easier than simply not reinventing the wheel and adding support for my adc into the ALSA stuff...? 

Thanks for the help and advice!