This Linux Kernel Module will install an interrupt based counter module to monitor and count pulses on a GPIO pin.  Short of specialized
hardware add ons, this is the fastest way to count pulses in Linux.

Building
--------
Building is easy.  simply type:
make

Installing the Module
---------------------
from the directory you built in, run the following
sudo insmod gpio-counter.ko gpio_pin=###
where ### is the gpio pin you want to monitor (check the NOTE below)

Parameters
----------
There are two configurable parameters:
  gpio_pin         : The GPIO pin you want to use.  This is the KERNEL GPIO pin, not the one you're probably thiking of.  See the NOTE below.
  debounce_time_us : The number of microseconds for debouncing inputs.  Defaults to 0, but 20000 might be good for pushbuttons.

Reading the value
-----------------
Read the value of the counter by looking at
cat /sys/kernel/gpio-counter/pulse_count

Reset the value
---------------
You can reset the value by overwriting the count with zero
echo 0 > /sys/kernel/gpio-counter/pulse_count

NOTE on GPIO Pin numbers
------------------------
The gpio pin number passed into this module are the Kernel gpio numbers.  If you're using a Raspberry Pi, that means they're likely in the 
500-900 range.  If you pass something below 100 in, it'll fail.  To make matters worse, every release of RaspberryPi will likely have
different numbers for the same pin.  To get the pin number for YOUR particular board, run this command:
cat /sys/kernel/debug/gpio

NOTE on rollover
----------------
The count stored here is an unsigned 32-bit integer, which means that once it gets to 4,294,967,296 it'll wrap to 0.  If that's 
in the range of what you're dealing with, you'll probably be fine