Book Image

Mastering Linux Device Driver Development

By : John Madieu
Book Image

Mastering Linux Device Driver Development

By: John Madieu

Overview of this book

Linux is one of the fastest-growing operating systems around the world, and in the last few years, the Linux kernel has evolved significantly to support a wide variety of embedded devices with its improved subsystems and a range of new features. With this book, you’ll find out how you can enhance your skills to write custom device drivers for your Linux operating system. Mastering Linux Device Driver Development provides complete coverage of kernel topics, including video and audio frameworks, that usually go unaddressed. You’ll work with some of the most complex and impactful Linux kernel frameworks, such as PCI, ALSA for SoC, and Video4Linux2, and discover expert tips and best practices along the way. In addition to this, you’ll understand how to make the most of frameworks such as NVMEM and Watchdog. Once you’ve got to grips with Linux kernel helpers, you’ll advance to working with special device types such as Multi-Function Devices (MFD) followed by video and audio device drivers. By the end of this book, you’ll be able to write feature-rich device drivers and integrate them with some of the most complex Linux kernel frameworks, including V4L2 and ALSA for SoC.
Table of Contents (19 chapters)
1
Section 1:Kernel Core Frameworks for Embedded Device Driver Development
6
Section 2: Multimedia and Power Saving in Embedded Linux Systems
13
Section 3: Staying Up to Date with Other Linux Kernel Subsystems

Linux kernel development tips

The best Linux kernel development practices are inspired by existing kernel code. This way, you could certainly learn good practices. That said, we will not reinvent the wheel. We will focus on what is necessary for this chapter, that is, debugging. The most frequently used debugging method involves logging and printing. In order to leverage this time-tested debugging technique, the Linux kernel provides suitable logging APIs and exposes a kernel message buffer to store the logs. Though it may seem obvious, we will focus on the kernel logging APIs and learn how to manage the message buffer, either from within the kernel code or from user space.

Message printing

Message printing and logging are inherent to development, irrespective of whether we are in kernel space or user space. In a kernel, the printk() function has long since been the de facto kernel message printing function. It is similar to printf() in the C library, but with the concept of...