I'm trying to get I2C to run on Arch Linux with Kernel 3.6.11+ #352 PREEMPT with Raspberry Firmware from Jan 9, 2013 updated via rpi-update.
So far I have got good results by just loading the i2c-dev module via
# echo "i2c-dev" > /etc/modules-load.d/i2c-dev.conf
on system start. As mentioned in this I2C tutorial, the permissions on the devices
/dev/i2c-* are only set to root, but can be made accessible to anyone via
sudo chmod 666 /dev/i2c-*
temporarily. (After this, the C example at the bottom of that page works, with minor tweaks). The permissions are not persistent after reboot. There is some discussion on how to make that persistent, and one user states that installing the package
i2c-tools also should create a group
i2c which allows any member to access
/etc/group, there is no such group
i2c after installing
i2c-tools. Any idea why this group isn't there, or good alternatives how to give user-programs access to i2c?