GPIOd

GPIOd is a daemon designed to provide centralized, programmatic access to General Purpose Input/Output pins on embedded Linux systems. It abstracts hardware specifics behind a stable user-space API, enabling software to configure pin directions, read and write values, and monitor events without interacting directly with kernel interfaces. The goal is to simplify GPIO management in complex environments where multiple processes or services require coordinated access.

The daemon typically runs as a background service, managed by system initialization utilities such as systemd. It binds to a defined set of GPIO pins, enforces a permission model to prevent conflicts, and may offer features such as debouncing, edge detection, and safe shutdown handling. Clients communicate with GPIOd through interprocess communication mechanisms such as a local UNIX domain socket, D-Bus, or a lightweight HTTP/REST API, allowing scripts, automation systems, and containerized applications to control hardware without bespoke drivers.

Implementation approaches vary, but GPIOd generally relies on the Linux GPIO subsystem, interfacing with the kernel through available user-space interfaces. It may support multiple backends or backends targeted at specific hardware platforms, and can accommodate several pin banks, pull configurations, and alternate functions. By decoupling GPIO access from individual applications, GPIOd aims to reduce race conditions, simplify permission handling, and improve reliability in hardware-driven automation, robotics, and Internet of Things deployments.

See also: libgpiod, GPIO, embedded Linux, sysfs GPIO, D-Bus.