char devices and debugging

[<fh...@at...>]

I have been trying to learn how to program char devices.
Well really trying to get my Hypercom4+ and Delfina Plus cards
 to work.  I've made test drivers for both.  Both drivers contain printk
statements so I can see if they are doing anything remotely like they are
supposed to.  Even though the drivers seem to  compile OK and are
"installed" in the kernel, no printk statements are visible in the dmesg
output.  Is this a problem peculiar to char devices?  I suspect I have not
quite got the driver code installed correctly in the kernel source tree.

Can anyone tell me the general procedure for adding a driver
to the kernel?  i.e. so it can be chosen in the .config and loaded into
the kernel?  Or maybe point me to some docs somewhere.

Fred