This FUSE based virtual filesystem emulates the deprecated /sys/class/gpio method of manipulating GPIOs. I wrote this tool to see if it is possible to maintain backwards compatibility for code deployed on a number of Raspberry Pis.
This code is still work in progress and should not be considered stable.
While the new method using gpiod is really powerful, the simplicity of just poking around in a few files is sometimes still hard to beat.
I only tested on Raspberry Pi OS. Compiling requires libfuse3-dev and unfortunately libgpiod 2.1 which Raspberry Pi Bookworm currently doesn't ship. They still have 1.6.
So you'll have to compile libgpiod 2.1 from source first.
Once that's done, just type make and you should get the sysfs-gpio-shim binary.
Not sure how to best automate this on Raspberry Pi OS. Manually it works like this. As root:
GPIO_GID="$(cut -d: -f3 < <(getent group gpio))"
./sysfs-gpio-shim -o default_permissions,allow_other,gid=$GPIO_GID /sys/class/gpio
This will shadow the existing /sys/class/gpio directory with the emulated filesystem provided by this tool.
If you're done and no one is using the files in
/sys/class/gpio you can unmount the filesystem as
usual using umount /sys/class/gpio.
I only tried a simple push button connected to GPIO18 on a Pi5 as well as some tests using multiple GPIOs on a Pi3. Edge detection by polling /value should work.
Setting active low, setting or reading the current value and exporting/unexporting the GPIO works too.
The behaviour should be mostly identical to what the sysfs implementation did. See also TODO.md.
Non-Pi devices are not supported and no effort will be made by me to change this. Sorry.
Probably garbage. If you're using sysfs-based GPIO control and expect performance, you're doing it wrong.
If you find a bug, feel free to open an issue. If you use this tool and it works well, please also let me know :)