You're reading from Mastering Linux Device Driver Development Write custom device drivers to support computer peripherals in Linux operating systems

Product type Paperback

Published in Jan 2021

Publisher Packt

ISBN-13 9781789342048

Length 646 pages

Edition 1st Edition

Languages

C++

Tools

Linux

Concepts

Embedded Systems

Author (1):

John Madieu

View More author details

Table of Contents (19) Chapters

Preface

1. Section 1:Kernel Core Frameworks for Embedded Device Driver Development

2. Chapter 1: Linux Kernel Concepts for Embedded Developers FREE CHAPTER

3. Chapter 2: Leveraging the Regmap API and Simplifying the Code

4. Chapter 3: Delving into the MFD Subsystem and Syscon API

5. Chapter 4: Storming the Common Clock Framework

6. Section 2: Multimedia and Power Saving in Embedded Linux Systems

7. Chapter 5: ALSA SoC Framework – Leveraging Codec and Platform Class Drivers

8. Chapter 6: ALSA SoC Framework – Delving into the Machine Class Drivers

9. Chapter 7: Demystifying V4L2 and Video Capture Device Drivers

10. Chapter 8: Integrating with V4L2 Async and Media Controller Frameworks

11. Chapter 9:Leveraging the V4L2 API from the User Space

12. Chapter 10: Linux Kernel Power Management

13. Section 3: Staying Up to Date with Other Linux Kernel Subsystems

14. Chapter 11: Writing PCI Device Drivers

15. Chapter 12: Leveraging the NVMEM Framework

16. Chapter 13: Watchdog Device Drivers

17. Chapter 14: Linux Kernel Debugging Tips and Best Practices

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Machine routing consideration

The machine driver can alter (or should I say append) the routes defined from within the codec. It has the last word on which codec pins must be used, for example.

Codec pins

Codec pins are meant to be connected to the board connectors. The available codec pins are defined in the codec driver using the SND_SOC_DAPM_INPUT and SND_SOC_DAPM_OUTPUT macros. These macros can be searched with the grep command in the codec driver in order to find the available PIN.

For example, the sgtl5000 codec driver defines the following output and input:

static const struct snd_soc_dapm_widget sgtl5000_dapm_widgets[] = {
    SND_SOC_DAPM_INPUT("LINE_IN"),
    SND_SOC_DAPM_INPUT("MIC_IN"),
    SND_SOC_DAPM_OUTPUT("HP_OUT"),
    SND_SOC_DAPM_OUTPUT("LINE_OUT"),
    SND_SOC_DAPM_SUPPLY("Mic Bias", SGTL5000_CHIP_MIC_CTRL...