The kernel IR decoders (drivers/media/rc/ir-*-decoder.c) 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, for which lircd is need to decode the IR . 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. It might also be possible to support non-button devices such as analog directional pads or air conditioning remote controls and decode the target temperature in bpf, and pass that to an input device. 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 v4: - Renamed rc_dev_bpf_{attach,detach,query} to lirc_bpf_{attach,detach,query} - Fixed error path in lirc_bpf_query - Rebased on bpf-next Changes since v3: - Implemented review comments from Quentin Monnet and Y Song (thanks!) - More helpful and better formatted bpf helper documentation - Changed back to bpf_prog_array rather than open-coded implementation - scancodes can be 64 bit - bpf gets passed values in microseconds, not nanoseconds. microseconds is more than than enough (IR receivers support carriers upto 70kHz, at which point a single period is already 14 microseconds). Also, this makes it much more consistent with lirc mode2. - Since it looks much more like lirc mode2, rename the program type to BPF_PROG_TYPE_LIRC_MODE2. - Rebased on bpf-next Changes since v2: - Fixed locking issues - Improved self-test to cover more cases - Rebased on bpf-next again 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 (3): bpf: bpf_prog_array_copy() should return -ENOENT if exclude_prog not found media: rc: introduce BPF_PROG_LIRC_MODE2 bpf: add selftest for lirc_mode2 type program drivers/media/rc/Kconfig | 13 + drivers/media/rc/Makefile | 1 + drivers/media/rc/bpf-lirc.c | 313 ++++++++++++++++++ drivers/media/rc/lirc_dev.c | 30 ++ drivers/media/rc/rc-core-priv.h | 21 ++ drivers/media/rc/rc-ir-raw.c | 12 +- include/linux/bpf_lirc.h | 29 ++ include/linux/bpf_types.h | 3 + include/uapi/linux/bpf.h | 53 ++- kernel/bpf/core.c | 11 +- kernel/bpf/syscall.c | 7 + kernel/trace/bpf_trace.c | 2 + tools/bpf/bpftool/prog.c | 1 + tools/include/uapi/linux/bpf.h | 53 ++- tools/include/uapi/linux/lirc.h | 217 ++++++++++++ tools/lib/bpf/libbpf.c | 1 + tools/testing/selftests/bpf/.gitignore | 1 + tools/testing/selftests/bpf/Makefile | 7 +- tools/testing/selftests/bpf/bpf_helpers.h | 5 + .../testing/selftests/bpf/test_lirc_mode2.sh | 28 ++ .../selftests/bpf/test_lirc_mode2_kern.c | 23 ++ .../selftests/bpf/test_lirc_mode2_user.c | 149 +++++++++ 22 files changed, 971 insertions(+), 9 deletions(-) create mode 100644 drivers/media/rc/bpf-lirc.c create mode 100644 include/linux/bpf_lirc.h create mode 100644 tools/include/uapi/linux/lirc.h create mode 100755 tools/testing/selftests/bpf/test_lirc_mode2.sh create mode 100644 tools/testing/selftests/bpf/test_lirc_mode2_kern.c create mode 100644 tools/testing/selftests/bpf/test_lirc_mode2_user.c -- 2.17.0
