Accessing serial port from TinyX

[Ping Cheng]

This may not be the proper list to post a TinyX question.  But I see a
few names in the source that are members of X.Org now. It should be a
simple one for those who worked on the code.

I am trying to let my driver communicate with a serial device
(specifically, a Wacom serial device). This device works with my X.Org
driver, which uses xf86SerialOpen and other related xf86 serial calls
to communicate with the device. However, TinyX doesn't support those
calls.  So, I have to "hack" into the original ones. The driver always
fails at the tcsetattr() call with errno=25. Man page tells me:
ENOTTY  Inapporatriate fd.

What does this mean to me? How do I fix it? Or at least, how do I
trace into the problem.

Any suggestion would be greatly appreciated.

Ping