Thread (14 messages) 14 messages, 6 authors, 2018-05-26

Re: [PATCH v4 2/3] media: rc: introduce BPF_PROG_LIRC_MODE2

From: Alexei Starovoitov <hidden>
Date: 2018-05-25 20:45:18
Also in: linux-media, lkml

On Fri, May 18, 2018 at 03:07:29PM +0100, Sean Young wrote:
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.

Signed-off-by: Sean Young <sean@mess.org>
...
quoted hunk ↗ jump to hunk
 enum bpf_attach_type {
@@ -158,6 +159,7 @@ enum bpf_attach_type {
 	BPF_CGROUP_INET6_CONNECT,
 	BPF_CGROUP_INET4_POST_BIND,
 	BPF_CGROUP_INET6_POST_BIND,
+	BPF_LIRC_MODE2,
 	__MAX_BPF_ATTACH_TYPE
 };
 
@@ -1902,6 +1904,53 @@ union bpf_attr {
  *		egress otherwise). This is the only flag supported for now.
  *	Return
  *		**SK_PASS** on success, or **SK_DROP** on error.
+ *
+ * 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** () 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**".
Hi Sean,

thank you for working on this. The patch set looks good to me.
I'd only ask to change above two helper names to something more specific.
Since BPF_PROG_TYPE_LIRC_MODE2 is the name of new prog type and kconfig.
May be bpf_lirc2_keydown() and bpf_lirc2_repeat() ?
quoted hunk ↗ jump to hunk
@@ -1576,6 +1577,8 @@ static int bpf_prog_attach(const union bpf_attr *attr)
 	case BPF_SK_SKB_STREAM_PARSER:
 	case BPF_SK_SKB_STREAM_VERDICT:
 		return sockmap_get_from_fd(attr, BPF_PROG_TYPE_SK_SKB, true);
+	case BPF_LIRC_MODE2:
+		return rc_dev_prog_attach(attr);
...
+	case BPF_LIRC_MODE2:
+		return rc_dev_prog_detach(attr);
and similar rename for internal function names that go into bpf core.

Please add accumulated acks when you respin.

Thanks
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