IR decoding using BPF

The kernel IR decoders support the most widely used IR protocols, but there
are many protocols which are not supported[1]. For example, the
lirc-remotes[2] repo has over 2700 remotes, many of which are not supported
by rc-core. There is a "long tail" of unsupported IR protocols.

IR encoding is done in such a way that some simple circuit can decode it;
therefore, bpf is ideal.

In order to support all these protocols, here we have bpf based IR decoding.
The idea is that user-space can define a decoder in bpf, attach it to
the rc device through the lirc chardev.

Separate work is underway to extend ir-keytable to have an extensive library
of bpf-based decoders, and a much expanded library of rc keymaps. 

Another future application would be to compile IRP[3] to a IR BPF program, and
so support virtually every remote without having to write a decoder for each.

Thanks,

Sean Young

[1] http://www.hifi-remote.com/wiki/index.php?title=DecodeIR
[2] https://sourceforge.net/p/lirc-remotes/code/ci/master/tre...
[3] http://www.hifi-remote.com/wiki/index.php?title=IRP_Notation

Sean Young (4):
  media: rc: introduce BPF_PROG_IR_DECODER
  media: bpf: allow raw IR decoder bpf programs to be used
  media: rc bpf: move ir_raw_event to uapi
  samples/bpf: an example of a raw IR decoder

 drivers/media/rc/Kconfig                  |   8 +
 drivers/media/rc/Makefile                 |   1 +
 drivers/media/rc/ir-bpf-decoder.c         | 284 ++++++++++++++++++++++
 drivers/media/rc/lirc_dev.c               |  30 +++
 drivers/media/rc/rc-core-priv.h           |  15 ++
 drivers/media/rc/rc-ir-raw.c              |   5 +
 include/linux/bpf_types.h                 |   3 +
 include/media/rc-core.h                   |  19 +-
 include/uapi/linux/bpf.h                  |  17 +-
 include/uapi/linux/bpf_rcdev.h            |  24 ++
 kernel/bpf/syscall.c                      |   7 +
 samples/bpf/Makefile                      |   4 +
 samples/bpf/bpf_load.c                    |   9 +-
 samples/bpf/grundig_decoder_kern.c        | 112 +++++++++
 samples/bpf/grundig_decoder_user.c        |  54 ++++
 tools/bpf/bpftool/prog.c                  |   1 +
 tools/include/uapi/linux/bpf.h            |  17 +-
 tools/testing/selftests/bpf/bpf_helpers.h |   6 +
 18 files changed, 594 insertions(+), 22 deletions(-)
 create mode 100644 drivers/media/rc/ir-bpf-decoder.c
 create mode 100644 include/uapi/linux/bpf_rcdev.h
 create mode 100644 samples/bpf/grundig_decoder_kern.c
 create mode 100644 samples/bpf/grundig_decoder_user.c

-- 
2.17.0