A list of chapters and sections which would be of use while working on project 4 is listed below. The minimum you need to read for this project are 
Chapters 2,3,5. The rest are listed for completeness so that you can look things up. Feel free to explore beyond what is listed. 
You can find the book here: http://lwn.net/Kernel/LDD3/

Chapter 1: Introduction to Device Drivers
Loadable Modules
Classes of Devices and Modules

Chapter 2:Building and Running Modules
The Hello World Module
Kernel Modules Versus Applications
User Space and Kernel Space
Concurrency in the Kernel
Compiling and Loading
Loading and Unloading Modules
Preliminaries
Initialization and Shutdown
Module-Loading Races
Module Parameters

Chapter 3: Char devices
The Design of scull
Major and Minor Numbers
The Internal Representation of Device Numbers
Allocating and Freeing Device Numbers
Dynamic Allocation of Major Numbers
Some Important Data Structures
Char Device Registration
open and release
scull’s Memory Usage
read and write

Chapter 4: Debugging Techniques
Debugging by Printing

Chapter 5:Concurrency and Race Conditions
Concurrency and Its Management
Semaphores and Mutexes
Locking Traps
Alternatives to Locking

Chapter 6: Advanced Char Driver Operations
Simple Sleeping

Chapter 8: Allocating Memory
The Real Story of kmalloc