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

Example of writing a platform driver from scratch

This section will try to summarize as far as possible the knowledge that has been acquired so far throughout the chapter. Now, let's imagine a platform device that is memory-mapped and that the memory range through which it can be controlled starts at 0x02008000 and is 0x4000 in size. Then, let's say this platform device can interrupt the CPU upon completion of its jobs and that this interrupt line number is 31. To keep things simple, let's not require any other resource for this device (we could have imagined clocks, DMAs, regulators, and so on).

To start with, let's instantiate this platform device from the device tree. If you remember, for a node to be registered as a platform device by the platform core, the direct parent of this node must have simple-bus in its compatible string list, and this is what is implemented here:

demo {
    compatible = "simple-bus";
  ...