Merge branch 'bpf-ir-decoder'

Sean Young says:

====================
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.

[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@gmail.com> and
   Randy Dunlap <rdunlap@infradead.org>
 - 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
====================

Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>

2 files changed, 32 insertions, 0 deletions

diff --git a/include/linux/bpf_lirc.h b/include/linux/bpf_lirc.h
new file mode 100644
index 000000000000..5f8a4283092d
--- /dev/null
+++ b/include/linux/bpf_lirc.h
@@ -0,0 +1,29 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _BPF_LIRC_H
+#define _BPF_LIRC_H
+
+#include <uapi/linux/bpf.h>
+
+#ifdef CONFIG_BPF_LIRC_MODE2
+int lirc_prog_attach(const union bpf_attr *attr);
+int lirc_prog_detach(const union bpf_attr *attr);
+int lirc_prog_query(const union bpf_attr *attr, union bpf_attr __user *uattr);
+#else
+static inline int lirc_prog_attach(const union bpf_attr *attr)
+{
+	return -EINVAL;
+}
+
+static inline int lirc_prog_detach(const union bpf_attr *attr)
+{
+	return -EINVAL;
+}
+
+static inline int lirc_prog_query(const union bpf_attr *attr,
+				  union bpf_attr __user *uattr)
+{
+	return -EINVAL;
+}
+#endif
+
+#endif /* _BPF_LIRC_H */
diff --git a/include/linux/bpf_types.h b/include/linux/bpf_types.h
index b161e506dcfc..c5700c2d5549 100644
--- a/include/linux/bpf_types.h
+++ b/include/linux/bpf_types.h
@@ -26,6 +26,9 @@ BPF_PROG_TYPE(BPF_PROG_TYPE_RAW_TRACEPOINT, raw_tracepoint)
 #ifdef CONFIG_CGROUP_BPF
 BPF_PROG_TYPE(BPF_PROG_TYPE_CGROUP_DEVICE, cg_dev)
 #endif
+#ifdef CONFIG_BPF_LIRC_MODE2
+BPF_PROG_TYPE(BPF_PROG_TYPE_LIRC_MODE2, lirc_mode2)
+#endif
 
 BPF_MAP_TYPE(BPF_MAP_TYPE_ARRAY, array_map_ops)
 BPF_MAP_TYPE(BPF_MAP_TYPE_PERCPU_ARRAY, percpu_array_map_ops)