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Linux Device Drivers Development

You're reading from   Linux Device Drivers Development Develop customized drivers for embedded Linux

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Product type Paperback
Published in Oct 2017
Publisher Packt
ISBN-13 9781785280009
Length 586 pages
Edition 1st Edition
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Author (1):
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John Madieu John Madieu
Author Profile Icon John Madieu
John Madieu
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Toc

Table of Contents (23) Chapters Close

Preface 1. Introduction to Kernel Development FREE CHAPTER 2. Device Driver Basis 3. Kernel Facilities and Helper Functions 4. Character Device Drivers 5. Platform Device Drivers 6. The Concept of Device Tree 7. I2C Client Drivers 8. SPI Device Drivers 9. Regmap API – A Register Map Abstraction 10. IIO Framework 11. Kernel Memory Management 12. DMA – Direct Memory Access 13. The Linux Device Model 14. Pin Control and GPIO Subsystem 15. GPIO Controller Drivers – gpio_chip 16. Advanced IRQ Management 17. Input Devices Drivers 18. RTC Drivers 19. PWM Drivers 20. Regulator Framework 21. Framebuffer Drivers 22. Network Interface Card Drivers

Module parameters

As a user program does, a kernel module can accept arguments from the command line. This allows dynamically changing the behavior of the module according to given parameters, and can help the developer not having to indefinitely change/compile the module during a test/debug session. In order to set this up, you should first declare the variables that will hold the values of command line arguments, and use the module_param() macro on each of these. The macro is defined in include/linux/moduleparam.h (this should be included in the code too: #include <linux/moduleparam.h>), shown as follows:

module_param(name, type, perm); 

This macro contains the following elements:

  • name: The name of the variable used as the parameter
  • type: The parameter's type (bool, charp, byte, short, ushort, int, uint, long, ulong), where charp stands for char pointer
  • perm: This...
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