RasPi GPIO driver

[sarraciro]

Hi all,
I'm trying to write a simple driver to use raspberry pi gpio.
I've found some examples for the POSIX approach (& I tried it with
success) but I'm more interesting to pure C solution.
I read the RTEMS's documentation but it's too general (for my
know-how) ... and  I've read the BCM2835 datasheet for register
addresses ...  I understood the relevance to use the pointers for access
to the memory...but I'm stucking until now I don't understand how to
move on...
Any suggestions or lectures for understand how to complete the task? 
thank you
rc