Introduction to Pin Muxing and GPIO Control Under Linux
summary
Covers how package pads map to pad circuitry and the kernel subsystems that control them, noting pinctrl merged in Linux 3.2 and the original gpiolib submission in 2008; explains pin/ group/ function names, runtime-selectable pinmux states via device-tree pinmux states, and conflict checking kept simple by storing active groups. Shows concrete APIs and callbacks: pinctrl ops, gpio controller callbacks (direction_output / get / set), consumer.h vs driver.h, gpio descriptor use to get/set an amp enable line, and handling of active_low and open-drain flags.
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chapters (8)
- 0:00Start
- 3:06Hardware Design
- 5:54Open Drain Pads
- 7:53Functions
- 18:27Conflict Checking
- 19:41Pin Control
- 24:35Gpio Framework
- 32:45Jpro Flags
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