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

Framework architecture and the main data structures

Video devices are becoming increasingly complex. In such devices, hardware often comprises several integrated IPs that need to cooperate with one another in a controlled manner, and this leads to complex V4L2 drivers. This requires figuring out the architecture prior to delving into the code and this is precisely the requirement that this section addresses.

It is known that drivers normally mirror the hardware model in programming. In the V4L2 context, the diverse IP components are modeled as software blocks called sub-devices. V4L2 sub-devices are usually kernel-only objects. Moreover, if the V4L2 driver implements the media device API (which we will discuss in the next chapter, Chapter 8, Integrating with V4L2 Async and Media Controller Frameworks), those sub-devices will automatically inherit from media entities, allowing applications to enumerate the sub-devices and to discover the hardware topology using the media framework...