Getting a Wacom Tablet in Toshiba M750 laptop working

[miyamoto moesasji]

I'm trying to get a Wacom tablet in a Toshiba M750 laptop to work
properly. This is a serial tablet (pen/touch) that is connected to the
ACPI bus only and  does not show up in dmesg for FreeBSD 9 stable. I'm
making progress, but am at the stage where a hint would really help.

1) I've patched the source along the lines of
http://lists.freebsd.org/pipermail/svn-src-stable-7/2010-January/002344.html,
which makes it appear in dmesg on the correct IRQ and port. This is
just adding a similar line as in that patch, but with 0x09f0235c for
the WACF09 tablet in this laptop. After this

dmesg -a | grep uart reports uart2: <16550 or compatible> port
0x338-0x33f irq 4 on acpi0

Which is as it should be for this device.

2) However hexdump /dev/ttyu2 does not give any response when moving
the pen around the screen, which I think it should if working
correctly.

3) Explicitly opening a serial connection on this port, using cu -l
/dev/ttyu2 -s 11520 indeed shows responses when moving the pen or my
fingers around the screen.

As the tablet works when opening a duplex connection to it the problem
is probably because no connection is opened upon booting. However even
with this information I don't see how to fix it. Could anyone point me
in the correct direction how to get further?