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Linux Device Driver Development

Linux Device Driver Development

By : John Madieu
4.4 (7)
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Linux Device Driver Development

Linux Device Driver Development

4.4 (7)
By: John Madieu

Overview of this book

Linux is by far the most-used kernel on embedded systems. Thanks to its subsystems, the Linux kernel supports almost all of the application fields in the industrial world. This updated second edition of Linux Device Driver Development is a comprehensive introduction to the Linux kernel world and the different subsystems that it is made of, and will be useful for embedded developers from any discipline. You'll learn how to configure, tailor, and build the Linux kernel. Filled with real-world examples, the book covers each of the most-used subsystems in the embedded domains such as GPIO, direct memory access, interrupt management, and I2C/SPI device drivers. This book will show you how Linux abstracts each device from a hardware point of view and how a device is bound to its driver(s). You’ll also see how interrupts are propagated in the system as the book covers the interrupt processing mechanisms in-depth and describes every kernel structure and API involved. This new edition also addresses how not to write device drivers using user space libraries for GPIO clients, I2C, and SPI drivers. By the end of this Linux book, you’ll be able to write device drivers for most of the embedded devices out there.
Table of Contents (23 chapters)
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1
Section 1 -Linux Kernel Development Basics
6
Section 2 - Linux Kernel Platform Abstraction and Device Drivers
12
Section 3 - Making the Most out of Your Hardware
18
Section 4 - Misc Kernel Subsystems for the Embedded World

Getting the most out of the GPIO consumer interface

The GPIO is a feature, or a mode in which a pin can operate, in terms of hardware. It is nothing more than a digital line that may be used as an input or output and has just two values (or states): 1 for high or 0 for low. The kernel's GPIO subsystem includes all of the functions you'll need to set up and manage GPIO lines from within your driver.

Before using a GPIO from within the driver, it must first be claimed by the kernel. It's a means to take control of a GPIO and prohibit other drivers from using it, as well as preventing the controller driver from being unloaded.

After claiming control of the GPIO, you can do the following:

  • Set the direction and, if needed, set the GPIO configuration.
  • If it's being used as an output, start toggling its output state (driving the line high or low).
  • If used as input, set the debounce-interval if needed and read the state. For a GPIO line mapped to an...
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