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

Chapter 7: Demystifying V4L2 and Video Capture Device Drivers

Video has long been inherent in embedded systems. Given that Linux is the favorite kernel used in such systems, it goes without saying that it natively embeds its support for video. This is the so-called V4L2, which stands for Video 4 (for) Linux 2. Yes! 2 because there was a first version, V4L. V4L2 augments V4L with memory management features and other elements that make this framework as generic as possible. Through this framework, the Linux kernel is able to deal with camera devices and the bridge to which they are connected, as well as the associated DMA engines. These are not the only elements supported by V4L2. We will begin with an introduction to framework architecture, learning how it is organized, and walk through the main data structures it comprises. Then, we will learn how to design and write the bridge device driver, the one responsible for DMA operations, and finally, we will delve into sub-device drivers...