Kernel device driver development is one of the most important parts of a complex operating system, which is what Linux is. Device drivers are very important for developers that use a computer as a monitoring or administrative machine in real environments such as industry, domestic, or medical applications. In fact, even if Linux is now widely supported everywhere, new peripherals are created every day, and these devices need drivers to be efficiently used on a GNU/Linux machine.
This book will present the implementation of a complete character driver (usually called a char driver) by presenting all the necessary techniques to exchange data between the kernel and userspace, to implement process synchronization with the peripheral's interrupts, to get access to I/O memory mapped to (internal or external) devices, and to efficiently manage the time within the kernel.
All code presented in this book is compatible with Linux 4.18+ releases (that is, as far as the latest 5.x kernels). The code can be tested on the Marvell ESPRESSObin, which has an onboard ARM 64-bit CPU, but any other similar GNU/Linux embedded device can be used. In this manner, the readers can verify whether what they have read has been correctly understood.
