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>

1 files changed, 52 insertions, 1 deletions

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