media: rc: introduce BPF_PROG_LIRC_MODE2

Add support for BPF_PROG_LIRC_MODE2. This type of BPF program can call
rc_keydown() to reported decoded IR scancodes, or rc_repeat() to report
that the last key should be repeated.

The bpf program can be attached to using the bpf(BPF_PROG_ATTACH) syscall;
the target_fd must be the /dev/lircN device.

Acked-by: Yonghong Song <yhs@fb.com>
Signed-off-by: Sean Young <sean@mess.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>

3 files changed, 84 insertions, 1 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)
diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
index 33f37eb0b6bf..64ac0f7a689e 100644
--- a/include/uapi/linux/bpf.h
+++ b/include/uapi/linux/bpf.h
@@ -143,6 +143,7 @@ enum bpf_prog_type {
 	BPF_PROG_TYPE_RAW_TRACEPOINT,
 	BPF_PROG_TYPE_CGROUP_SOCK_ADDR,
 	BPF_PROG_TYPE_LWT_SEG6LOCAL,
+	BPF_PROG_TYPE_LIRC_MODE2,
 };
 
 enum bpf_attach_type {
@@ -162,6 +163,7 @@ enum bpf_attach_type {
 	BPF_CGROUP_INET6_POST_BIND,
 	BPF_CGROUP_UDP4_SENDMSG,
 	BPF_CGROUP_UDP6_SENDMSG,
+	BPF_LIRC_MODE2,
 	__MAX_BPF_ATTACH_TYPE
 };
 
@@ -2005,6 +2007,53 @@ union bpf_attr {
  * 		direct packet access.
  *	Return
  * 		0 on success, or a negative error in case of failure.
+ *
+ * int bpf_rc_keydown(void *ctx, u32 protocol, u64 scancode, u32 toggle)
+ *	Description
+ *		This helper is used in programs implementing IR decoding, to
+ *		report a successfully decoded key press with *scancode*,
+ *		*toggle* value in the given *protocol*. The scancode will be
+ *		translated to a keycode using the rc keymap, and reported as
+ *		an input key down event. After a period a key up event is
+ *		generated. This period can be extended by calling either
+ *		**bpf_rc_keydown** () again with the same values, or calling
+ *		**bpf_rc_repeat** ().
+ *
+ *		Some protocols include a toggle bit, in case the button	was
+ *		released and pressed again between consecutive scancodes.
+ *
+ *		The *ctx* should point to the lirc sample as passed into
+ *		the program.
+ *
+ *		The *protocol* is the decoded protocol number (see
+ *		**enum rc_proto** for some predefined values).
+ *
+ *		This helper is only available is the kernel was compiled with
+ *		the **CONFIG_BPF_LIRC_MODE2** configuration option set to
+ *		"**y**".
+ *
+ *	Return
+ *		0
+ *
+ * int bpf_rc_repeat(void *ctx)
+ *	Description
+ *		This helper is used in programs implementing IR decoding, to
+ *		report a successfully decoded repeat key message. This delays
+ *		the generation of a key up event for previously generated
+ *		key down event.
+ *
+ *		Some IR protocols like NEC have a special IR message for
+ *		repeating last button, for when a button is held down.
+ *
+ *		The *ctx* should point to the lirc sample as passed into
+ *		the program.
+ *
+ *		This helper is only available is the kernel was compiled with
+ *		the **CONFIG_BPF_LIRC_MODE2** configuration option set to
+ *		"**y**".
+ *
+ *	Return
+ *		0
  */
 #define __BPF_FUNC_MAPPER(FN)		\
 	FN(unspec),			\
@@ -2083,7 +2132,9 @@ union bpf_attr {
 	FN(lwt_push_encap),		\
 	FN(lwt_seg6_store_bytes),	\
 	FN(lwt_seg6_adjust_srh),	\
-	FN(lwt_seg6_action),
+	FN(lwt_seg6_action),		\
+	FN(rc_repeat),			\
+	FN(rc_keydown),
 
 /* integer value in 'imm' field of BPF_CALL instruction selects which helper
  * function eBPF program intends to call