passing variables to/from kernel space

[Oliver Ryan <oryan@physics.nuigalway.ie>]

Hi all,

complete new guy to the Linux kernel and module programming.  I've written 
a module that can read to/from memory mapped space to the registers of a 
PCI card (PLX9054 chip).  It's simply loaded and unloaded using insmod and 
rmmod, and isn't left to reside in the kernel -- it's just for a quick 
initialisation of register values after which I can forget about them.

1.  How do I pass register values entered in user space to the module so 
that these values are loaded into the registers?  I've read up on 
copy_to/from_user and put/get_user but don't know how to implement them in 
working code.

2.  In a kernel module I want to call some function which will give me the 
time elapsed in seconds since Jan1 1970 - time() would do this in a user 
program, but what is it's equivalent for the kernel module?

3.  Is there a HOWTO or example code somewhere I can read up on (for system 
calls too, which might be a better way of doing things?) ?  I've looked at 
most kernel hacking stuff I think, but still can't find what I need.

I appreciate the help.  Thanks.

Oliver.

Dept. of Physics,
National University of Ireland, Galway,
Galway,
Ireland.

Tel: +353 (0)91 524411 ext. 2716
Fax: +353 (0)91 750584
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