TODO:
- checkpatch.pl fixes
  These checks should be ignored:
    CHECK:ALLOC_SIZEOF_STRUCT: Prefer kmalloc(sizeof(*board->private_data)...) over kmalloc(sizeof(struct xxx_priv)...)
    ./gpio/gpib_bitbang.c:50: ERROR:COMPLEX_MACRO: Macros with complex values should be enclosed in parenthese
  This warning will be addressed later:  WARNING:UNDOCUMENTED_DT_STRING: DT compatible string
- resolve XXX notes where possible
- fix FIXME notes
- clean-up commented-out code
- fix typos