Linux Device Driver Development: Everything you need to start with device driver development for Linux kernel and embedded Linux

708 Pages·2022·5.433 MB·English

by  John Madieu

Linux Device
Driver Development
Second Edition
Everything you need to start with device driver
development for Linux kernel and embedded Linux
John Madieu
BIRMINGHAM—MUMBAI
Linux Device Driver Development
Second Edition
Copyright © 2022 Packt Publishing
All rights reserved. No part of this book may be reproduced, stored in a retrieval system, or
transmitted in any form or by any means, without the prior written permission of the publisher,
except in the case of brief quotations embedded in critical articles or reviews.
Every effort has been made in the preparation of this book to ensure the accuracy of the
information presented. However, the information contained in this book is sold without warranty,
either express or implied. Neither the author, nor Packt Publishing or its dealers and distributors,
will be held liable for any damages caused or alleged to have been caused directly or indirectly by
this book.
Packt Publishing has endeavored to provide trademark information about all of the companies
and products mentioned in this book by the appropriate use of capitals. However, Packt Publishing
cannot guarantee the accuracy of this information.
Group Product Manager: Rahul Nair
Publishing Product Manager: Rahul Nair
Senior Editor: Shazeen Iqbal
Content Development Editor: Romy Dias
Technical Editor: Nithik Cheruvakodan
Copy Editor: Safis Editing
Project Coordinator: Shagun Saini
Proofreader: Safis Editing
Indexer: Tejal Daruwale Soni
Production Designer: Alishon Mendonca
Marketing Coordinator: Hemangi Lotlikar
First published: October 2017
Second edition: March 2022
Production reference: 1140322
Published by Packt Publishing Ltd.
Livery Place
35 Livery Street
Birmingham
B3 2PB, UK.
ISBN 978-1-80324-006-0
www.packt.com
I dedicate this book to Laëlle Stella, my beautiful darling daughter.
Contributors
About the author
John Madieu is an embedded Linux and kernel engineer living in Paris, France. His
main activity consists of developing device drivers and Board Support Packages (BSPs)
for companies in domains including IoT, automation, transport, healthcare, energy, and
the military. John is the founder and chief consultant of LABCSMART, a company that
provides training and services for embedded Linux and Linux kernel engineering. He is
an open source and embedded systems enthusiast, convinced that it is only by sharing
knowledge that we can learn more. He is passionate about boxing, which he practiced for
6 years professionally, and continues to channel this passion through training sessions that
he provides voluntarily.
I want to thank Jerôme Grard for his rather critical eye and his
suggestions for improvement. I would also like to personally thank Pacôme
Cyprien Nguefack, Claudia ATK, Elsie Zeufack, Loïca, and all those
who participated directly or indirectly in the writing of this book, for
accompanying me on this journey.
About the reviewer
Robertino Beniš has been involved in the embedded world for 15+ years, working on
projects from smart homes and mobile devices (shipped 10+ million devices worldwide)
to vehicle infotainment systems. He has worked with embedded Linux as well as with a
number of real-time operating systems, including bare metal (does anyone still remember
Qualcomm Brew?).
Currently, he is starting up NFTee Inc., California, in the blockchain engineering space,
and studying Russian at Minsk State Linguistic University in Belarus.
Thanks to my (start-up) CEO, Kyle, for his understanding while I dedicated
some time to reviewing this book, and to the city of Minsk as a whole, for
enabling a clean, peaceful, and comfortable environment in which to study,
work, and live.

Table of Contents
Preface
Section 1 - Linux Kernel Development Basics
1
Introduction to Kernel Development
Setting up the development Specifying compilation options 12
environment 4 Understanding the kernel
configuration process 14
Setting up the host machine 5
Building the Linux kernel 19
Getting the sources 8
Building and installing modules 23
Configuring and building the
Linux kernel 12 Summary 24
2
Understanding Linux Kernel Module Basic Concepts
An introduction to the concept Dealing with symbol exports
of modules 26 and module dependencies 42
Case study – module skeleton 27 An introduction to the concept of
module dependencies 43
Building a Linux kernel module 31
Learning some Linux kernel
Understanding the Linux kernel build
programming tips 46
system 31
Out-of-tree building 35 Error handling 47
In-tree building 38 Message printing – goodbye printk,
long life dev_*, pr_*, and net_* APIs 51
Handling module parameters 40
Summary 54
viii Table of Contents
3
Dealing with Kernel Core Helpers
Linux kernel locking The concepts of clocksource,
mechanisms and shared clockevent, and tick device 72
resources 56 Using standard kernel low-precision
(low-res) timers 87
Spinlocks 57
High-resolution timers (hrtimers) 93
Mutexes 61
Trylock methods 64 Implementing work-deferring
mechanisms 99
Dealing with kernel waiting,
sleeping, and delay mechanisms 66 Softirqs 100
Tasklets 105
Wait queue 66
Workqueues 110
Simple sleeping in the kernel 70
Workqueues' new generation 116
Kernel delay or busy waiting 71
Kernel interrupt handling 120
Understanding Linux kernel
time management 72 Designing and registering an interrupt
handler 121
Summary 140
4
Writing Character Device Drivers
The concept of major and minor 142 Implementing file operations 152
Character device data structure Exchanging data between the kernel
introduction 143 space and user space 153
Implementing the open file operation 153
An introduction to device file
operations 143 Implementing the release file operation 155
File representation in the kernel 146 Implementing the write file operation 156
Implementing the read file operation 159
Creating a device node 147
Implementing the llseek file operation 161
Device identification 147 The poll method 164
Registration and deregistration of The ioctl method 168
character
device numbers 148 Summary 172
Initializing and registering a character
device on the system 149
Table of Contents ix
Section 2 - Linux Kernel Platform
Abstraction and Device Drivers
5
Understanding and Leveraging the Device Tree
Understanding the basic Representing and addressing
concept of the device tree devices 191
mechanism 176
Handling SPI and I2C device addressing 192
The device tree naming convention 177 Memory-mapped devices and device
An introduction to the concept of addressing 194
aliases, labels, phandles, and paths 178
Handling resources 196
Understanding overwriting nodes and
properties 182 The struct resource 196
Device tree sources and compilers 183 Extracting application-specific data 200
Summary 206
6
Introduction to Devices, Drivers, and Platform Abstraction
Linux kernel platform Bus structure 219
abstraction and data structures 208
Device and driver matching
Device base structure 208
mechanism explained 220
Device driver base structure 210
Case study – the OF matching
Device/driver matching and module
mechanism 222
(auto) loading 216
Device declaration – populating devices 218 Summary 223
7
Understanding the Concept of Platform Devices and Drivers
Understanding the platform Allocating and registering platform
core abstraction in the Linux devices 229
kernel 226 How not to allocate platform devices
to your code 231
Dealing with platform devices 228
Working with platform resources 233