Book Image

Linux Device Drivers Development

By : John Madieu
Book Image

Linux Device Drivers Development

By: John Madieu

Overview of this book

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 devices throughout the World. Device drivers play a critical role in how well a Linux system performs. As Linux has turned out to be one of the most popular operating systems used, the interest in developing proprietary device drivers is also increasing steadily. This book will initially help you understand the basics of drivers as well as prepare for the long journey through the Linux Kernel. This book then covers drivers development based on various Linux subsystems such as memory management, PWM, RTC, IIO, IRQ management, and so on. The book also offers a practical approach on direct memory access and network device drivers. By the end of this book, you will be comfortable with the concept of device driver development and will be in a position to write any device driver from scratch using the latest kernel version (v4.13 at the time of writing this book).
Table of Contents (23 chapters)
Free Chapter
1
Introduction to Kernel Development

Device methods

In the struct fb_info structure, there is a .fbops field, which is an instance of the struct fb_ops structure. This structure contains a collection of functions that need to perform some operations on the framebuffer device. These are entry points for fbdev and fbcon tools. Some methods in that structure are mandatory, the minimum required for a framebuffer to work, whereas others are optional, and depend on the features the driver needs to expose, assuming the device itself supports those features.

The following is the definition of the struct fb_ops structure:

    struct fb_ops { 
   /* open/release and usage marking */ 
   struct module *owner; 
   int (*fb_open)(struct fb_info *info, int user); 
   int (*fb_release)(struct fb_info *info, int user); 
 
   /* For framebuffers with strange nonlinear layouts or that do not 
    * work with normal memory mapped...