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

Platform driver abstraction and architecture

Let's get warned before going further. Not all platform devices are handled by platform drivers (or, should I say, pseudo platform drivers). Platform drivers are dedicated to devices not based on conventional buses. I2C devices or SPI devices are platform devices, but rely on I2C or SPI buses, respectively, and not on platform buses. Everything needs to be done manually with the platform driver.

Probing and releasing the platform devices

The platform driver entry point is the probe method, invoked after a match with a platform device has occurred. This probe method has the following prototype:

int pdrv_probe(struct platform_device *pdev)

pdev corresponds to the platform device that has been instantiated in the traditional way or a fresh one allocated by the platform core because of the associated device tree node having a direct parent with simple-bus in its compatible property. Platform data and resources, if any, will...