Linux Device Drivers Development

The pin control subsystem

The pin control (pinctrl) subsystem allows managing pin muxing. In the DT, devices that need pins to be multiplexed in a certain way must declare the pin control configuration they need.

The pinctrl subsystem provides:

• Pin multiplexing, which allows for reusing the same pin for different purposes, such as one pin being a UART TX pin, GPIO line, or HSI data line. Multiplexing can affect groups of pins or individual pins.
• Pin configuration, applying electronic properties of pins such as pull-up, pull-down, driver strength, debounce period, and so on.

The purpose of this book is limited to using functions exported by the pin controller driver, and does not cover how to write a pin controller driver.