Are you a Certified Seating Services Provider?

Become a CSSP: This test program tests the parallel port.

I have a top half that gets the interrupt, and then the bottom half
task queues, to right now just printk a test message.

So you, as the Seating Services Provider (SSP) are responsible for
testing your computer to see whether or not the parallel port is
inverting, and if it is inverting, you will see this printk message
when you raise the parallel port pin 10 which we have (in the driver)
set to respond to IRQ.

Do the following:

make
insmod pptest.o
short pin10 to +5, if printk your parallel port is inverting.
short pin10 to gnd; if printk your parallel port is non inverting.