where can i get datasheet

["amol verule" <amol.debian@xxxxxxxxx>]

hi to all,
              i am new to device driver,i wrote pseudo char device driver.now i like to write keyboard and mouse device driver.
from where can i get a datasheet to proceed for writing driver??? or is there any way to write driver without datasheet?.
if linux kernel has driver for some device means datasheet ,may be available for free to use.,

thanks,
regards,
amol