devctl usage

I’ve read the other posts on this topic, reviewed source, read all the docs,
and I still cannot sort out the devctl usage with an input driver.

The task I’m attempting to accomplish is simple - I need to solicit my input
(touch) driver for data other than the pointer information it is originally
designed to provide. My first thought was to create a custom devctl
command. However, I cannot make heads-or-tails of the relationship between
the devctl “dcmd” parameter and the devctrl (input driver function) “event”
parameter. All my attempts to transmit a devctl message result in:

“ENOTTY: Inappropriate I/O control operation”

which according to devctl is:

“The dcmd argument isn’t a valid command for this device.”

I have used every combination of -r and -P when initiating my input driver,
and nothing has resulted in a transmitted devctl message.

Please advise on the parameter relationship between devctl and devctRl, and
on the overall use of devctl’s for my task.

Much appreciated,
Mike Kadour