[ltp] GPIO Info

[sensors]

Hi All

I need to access some General Purpose I/O ports ( GPIO ), but don't have
much idea about GPIO. I searched in the Google but couldn't get much
information. So can any one  send me the information or the links regarding
GPIO, like the h/w architecture,  sys calls to get the base address,   sys
calls to read, write and change the state of GPIO ports.
As in case of a PCI device, we  read the config space and get device base
address , so is there any similar way in case of GPIO to get the base
address.

Thanks in Advance............................