Book Image

Linux Device Driver Development - Second Edition

By : John Madieu
Book Image

Linux Device Driver Development - Second Edition

By: John Madieu

Overview of this book

Linux is by far the most-used kernel on embedded systems. Thanks to its subsystems, the Linux kernel supports almost all of the application fields in the industrial world. This updated second edition of Linux Device Driver Development is a comprehensive introduction to the Linux kernel world and the different subsystems that it is made of, and will be useful for embedded developers from any discipline. You'll learn how to configure, tailor, and build the Linux kernel. Filled with real-world examples, the book covers each of the most-used subsystems in the embedded domains such as GPIO, direct memory access, interrupt management, and I2C/SPI device drivers. This book will show you how Linux abstracts each device from a hardware point of view and how a device is bound to its driver(s). You’ll also see how interrupts are propagated in the system as the book covers the interrupt processing mechanisms in-depth and describes every kernel structure and API involved. This new edition also addresses how not to write device drivers using user space libraries for GPIO clients, I2C, and SPI drivers. By the end of this Linux book, you’ll be able to write device drivers for most of the embedded devices out there.
Table of Contents (23 chapters)
1
Section 1 -Linux Kernel Development Basics
6
Section 2 - Linux Kernel Platform Abstraction and Device Drivers
12
Section 3 - Making the Most out of Your Hardware
18
Section 4 - Misc Kernel Subsystems for the Embedded World

Chapter 5: Understanding and Leveraging the Device Tree

The device tree is an easy-to-read hardware description file, with a JSON-like formatting style. It is a simple tree structure where devices are represented by nodes and their properties. These properties can either be empty (that is, just the key to describe Boolean values) or key-value pairs, where the value can contain an arbitrary byte stream. This chapter is a simple introduction to device trees. Every kernel subsystem or framework has its own device tree binding, and we will talk about those specific bindings when we deal with the relevant topics.

The device tree originated from Open Firmware (OF), which is a standard endorsed by computer companies, and whose main purpose is to define interfaces for computer firmware systems. That said, you can find out more about device tree specification at http://www.devicetree.org/. Therefore, this chapter will cover the basics of the device tree, including the following:

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