Linux firewire drivers project: http://www.ffado.org/

The Motif XF isn't listed:
http://www.ffado.org/?q=devicesupport%2Flist&filter0=yamaha&filter1=&op2=OR

A quick google returns this thread, probably of interest:
http://www.motifator.com/index.php/forum/viewthread/442794/#456446

Otherwise, just try it: and see if it works. That's the easy way to find out.

This seems a related project: sponsored by Yamaha initially it seems..
http://mlanalsa.sourceforge.net/

I have no experience with this particular type of streaming driver / device, so I can't help much more :) -Harry