Good Day!
I've tried to get GPIO access working on 1B (Raspberry Pi B+) images
from [1], however, the "/dev/gpiomem" device is missing and access to
"/dev/mem" (some libaries fall back to that device) is denied (even as
root, and I don't even want to use "/dev/mem").
Searching the internet brough up some udev rules. So I tried thse
without success:
SUBSYSTEM=="gpio", GROUP="gpio", MODE="0660"
KERNEL=="gpiomem", GROUP="gpio", MODE="0660"
SUBSYSTEM=="bcm2835-gpiomem", GROUP="gpio", MODE="0660"
SUBSYSTEM=="bcm2835-gpiomem", KERNEL=="gpiomem", GROUP="gpio",
MODE="0660"
I later found /lib/udev/rules.d/60-rpi.gpio-common.rules and added these
rules. Also no success.
I can't find "gpiomem" in the kernel config.
In the official Raspberry Pi repository there once was a request [2] to
enable a kernel config "CONFIG_BCM2835_DEVGPIOMEM". This module was
apparently replaced by something called "raspberrypi-gpiomem" in commit
27543eeff4553f5caf7c6d8763c566042b047af0. Interestingly I can't find
that phrase in any other commit in their repo.
(Note: I'm aware that Debian does not refer to the Raspberry Pi [2]
repo, this just came up in my research.)
To me there seems to be kernel support missing or a config is not set.
Can someone please clarify on this?
Thank you.
Best regards,
Thomas.