[maemo-developers] Can anyone tell me how the N900 vibrator driver works?

[From: Jonathan Wilson]

I am looking for information on the driver the responds to 
/sys/class/i2c-adapter/i2c-1/1-0048/twl4030_vibra/pulse and in particular 
details of just what it does with the numbers.
Pointers to the source code for the driver in question may also help 
although I dont know the first thing about linux kernel drivers :P

I am attempting to create a clone of the N900 mce vibrator plugin (so that 
it can be extended and improved) and having this info would help me 
understand what is going on.