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

Driver methods

Drivers methods consist of probe() and remove() functions. Prior to going further with these method descriptions, let us set up our fb_ops structure:

static struct fb_ops myfb_ops = { 
   .owner        = THIS_MODULE, 
   .fb_check_var = myfb_check_var, 
   .fb_set_par   = myfb_set_par, 
   .fb_setcolreg = myfb_setcolreg, 
   .fb_fillrect  = cfb_fillrect, /* Those three hooks are */  
   .fb_copyarea  = cfb_copyarea, /* non accelerated and */ 
   .fb_imageblit = cfb_imageblit, /* are provided by kernel */ 
   .fb_blank     = myfb_blank, 
}; 
  • Probe: The driver probe function is in charge of initializing the hardware, creating the struct fb_info structure using the framebuffer_alloc() function, and using register_framebuffer() on it. The following sample assumes the device is memory mapped. Therefore, your nonmemory map can exist, such as screen sitting...