As per https://git.kernel.org/pub/scm/utils/i2c-tools/i2c-tools.git/about/ LICENSE is "LGPL-2.1+ GPL-2+" With USE-flag "python" https://git.kernel.org/pub/scm/utils/i2c-tools/i2c-tools.git/tree/py-smbus/smbusmodule.c is GPL-2. Reproducible: Always