Device Driver Help

Hi, I am very new to device driver area and has some basic knowledge of char and block device driver and linux kernel. I am little bit aware of some of subsystem of kernel but I am not able to co-relate which device driver file is pure software driver and more or less part of kernel subsystem to achieve hardware abstraction and which driver files deals with real hardware. It would be great help if someone can provide some real example with some open hardware datasheet, some basic code snippet will help me a lot. Thanks, A Kernel Newbie