Preface

The Linux kernel is a complex, portable, modular, and widely used piece of software, running on around 80% of servers and embedded systems in more than half of the devices throughout the world. Device drivers play a critical role in the context of how well a Linux system operates. As Linux has turned out to be one of the most popular operating systems, interest in developing personal device drivers is also increasing steadily.

A device driver is the link between the user space and hardware devices, through the kernel.

This book will begin with two chapters that will help you understand the basics of drivers and prepare you for the long journey through the Linux kernel. This book will then cover driver development based on Linux subsystems, such as memory management, industrial input/output (IIO), general-purpose input/output (GPIO), interrupt request (IRQ) management, and Inter-Integrated Circuit (I2C) and Serial Peripheral Interface (SPI). The book will also cover a practical approach to direct memory access and register map abstraction.

The source code in this book has been tested on both an x86 PC and UDOO QUAD from SECO, which is based on an ARM i.MX6 from NXP, with enough features and connections to allow us to cover all of the tests discussed in the book. Some drivers are also provided for testing purposes for inexpensive components, such as MCP23016 and 24LC512, which are an I2C GPIO controller and EEPROM memory, respectively.

By the end of this book, you will be comfortable with the concept of device driver development and will be able to write any device driver from scratch using the last stable kernel branch (v5.10.y at the time of writing).