In response to myself...
1) There isn't a HOWTO write a XFree86 Driver that I could find.
2) There is samples in the source code, as well as similar drivers
for touchscreen needs.
What I did was:
get the source code for xserver-xfree86
on debian:
cd /usr/local/src
apt-get source xserver-xfree86
then build the source in it's entirety
(so all the libraries and dependencies are build)
cd /usr/local/src/xfree86-4.3.0.dfsg.1/build-tree/xc-xserver-xfree86-dbg
make World
(wait...)
then go find the example driver you want to start hacking up
cd
/usr/local/src/xfree86-4.3.0.dfsg.1/build-tree/xc-xserver-xfree86-dbg/programs/Xserver/hw/xfree86/input/elographics
make a change to the source file to see your code changes work...
(I would suggest changing something that logs to screen, or the logfile)...
vi xf86Elo.c
make
cp elographics_drv.o /usr/X11R6/lib/modules/input/
make sure you're specifying that driver in XF86Config-4
Section "InputDevice"
...
Driver "elographics"
Option "Device" "/dev/ttyS0"
...
EndSection
Start your X server...
startx
See your change (or see the logging occur).
If that works.
You can now make changes to the source code, and see the changes.
###
NEXT UP: writing your driver for your hardware.
1) Request the Hardware Program manual from the manufacturer.
(in my case it was ELO that bought out CarrollTouch)
2) Write a simple C script that communicates to the device,
following the instructions from the Program manual.
(this was used to quickly debug serial device communication)
3) Incorporate your working C script in the appropriate places
into your x driver modified above.
4) Possibly change the name of the driver to something
that resembles your hardware.
5) Submit the code for review, or addition.
###
Which brings me to a question,
HOW DO I submit my code for review or addition?
Thanks!
On Mon, Mar 07, 2005 at 03:31:24PM -0800, todd wrote:
> I have:
> Correll Touch 5003-0768-01 (Correll Touch was bought out by Elo)
> -- an infra-red touchscreen wrapper.
> XFree86 Version 4.3.0.1 (Debian 4.3.0.dfsg.1-10 20041215174925)
>
> The linux docs for Elo:
> http://www.elotouch.com/support/linux.asp
> "Linux drivers for Elo touchscreens are available in the public
> domain, typically on Linux installation CDs and various FTP
> sites such as www.xfree86.org. These Linux drivers are compatible
> with Elo AT4 2215, AccuTouch E271-2210, IntelliTouch E281-2310,
> IntelliTouch 2500S, and CarrollTouch 4000S controllers."
>
> The problem:
> the eloprahics_drv.o spews "Dropping one byte in an attempt to
> synchronize"
> when used.
>
> Troubleshooting done:
> I have done a "od -h -w10 </dev/ttyS0" from the console,
> I have not received any characters when screen is touched,
> but I do see the cursor blinking rapidly, if I unplug the serial cable
> the blinking slows to regular console blinking pace.
>
> I have also plugged in an old serial mouse to /dev/ttyS0 and
> validated that cat /dev/ttyS0 works fine, so I know the port is
> /dev/ttyS0.
>
> TODO (Solution):
> Write/modify a driver to get this touchscreen working.
>
> HOW:
> I haven't seen any documentation on the best practices for writing
> a XFree86 Driver (or modifying one).
>
> Is there a step-by-step "HOWTO write a XFree86 Driver"?
>
> Thanks!
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