The gpio-chardev interface

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This interface is under development and is not currently available for general use.

The gpio-chardev interface allows access to specific GPIO chardev lines.

:warning: gpio-chardev is currently hidden behind an experimental feature flag until kernel improvements for the gpio-aggregator interface lands.

Interface documentation:

See Interface management and Supported interfaces for further details on how interfaces are used.

Developer details

Auto-connect: no

The interface operates as follows:

  • uses snap-gpio-helper to set up a virtual GPIO device exposing specific lines defined in the slot as character device node at /dev/snap/gpio-chardev/<slot-snap>/<slot-name>
  • sets up a symlink at /dev/snap/gpio-chardev/<plug-snap>/<plug-name> pointing at the virtual slot device
  • slot devices are given a specific udev tag, which consumer rules match on

Code examples

The test code can be found in the snapd repository: https://github.com/canonical/snapd/blob/master/interfaces/builtin/gpio_chardev_test.go

The source code for this interface is in the snapd repository: https://github.com/canonical/snapd/blob/master/interfaces/builtin/gpio_chardev.go