[PATCH v2 0/2] IR decoding using BPF

From: Sean Young
Date: Tue May 15 2018 - 14:50:31 EST


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/tree/remotes/
[3] http://www.hifi-remote.com/wiki/index.php?title=IRP_Notation

Changes since v1:
- Code review comments from Y Song <ys114321@xxxxxxxxx> and
Randy Dunlap <rdunlap@xxxxxxxxxxxxx>
- Re-wrote sample bpf to be selftest
- Renamed RAWIR_DECODER -> RAWIR_EVENT (Kconfig, context, bpf prog type)
- Rebase on bpf-next
- Introduced bpf_rawir_event context structure with simpler access checking

Sean Young (2):
media: rc: introduce BPF_PROG_RAWIR_EVENT
bpf: add selftest for rawir_event type program

drivers/media/rc/Kconfig | 10 +
drivers/media/rc/Makefile | 1 +
drivers/media/rc/bpf-rawir-event.c | 322 ++++++++++++++++++
drivers/media/rc/lirc_dev.c | 28 ++
drivers/media/rc/rc-core-priv.h | 19 ++
drivers/media/rc/rc-ir-raw.c | 3 +
include/linux/bpf_rcdev.h | 30 ++
include/linux/bpf_types.h | 3 +
include/uapi/linux/bpf.h | 55 ++-
kernel/bpf/syscall.c | 7 +
tools/bpf/bpftool/prog.c | 1 +
tools/include/uapi/linux/bpf.h | 55 ++-
tools/lib/bpf/libbpf.c | 1 +
tools/testing/selftests/bpf/Makefile | 7 +-
tools/testing/selftests/bpf/bpf_helpers.h | 6 +
tools/testing/selftests/bpf/test_rawir.sh | 37 ++
.../selftests/bpf/test_rawir_event_kern.c | 26 ++
.../selftests/bpf/test_rawir_event_user.c | 90 +++++
18 files changed, 696 insertions(+), 5 deletions(-)
create mode 100644 drivers/media/rc/bpf-rawir-event.c
create mode 100644 include/linux/bpf_rcdev.h
create mode 100755 tools/testing/selftests/bpf/test_rawir.sh
create mode 100644 tools/testing/selftests/bpf/test_rawir_event_kern.c
create mode 100644 tools/testing/selftests/bpf/test_rawir_event_user.c

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2.17.0