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Date: Mon, 14 May 2018 22:34:57 -0700
From: Y Song <ys114321@...il.com>
To: Sean Young <sean@...s.org>
Cc: linux-media@...r.kernel.org, linux-kernel@...r.kernel.org,
Alexei Starovoitov <ast@...nel.org>,
Mauro Carvalho Chehab <mchehab@...nel.org>,
Daniel Borkmann <daniel@...earbox.net>,
netdev <netdev@...r.kernel.org>,
Matthias Reichl <hias@...us.com>,
Devin Heitmueller <dheitmueller@...nellabs.com>
Subject: Re: [PATCH v1 4/4] samples/bpf: an example of a raw IR decoder
On Mon, May 14, 2018 at 2:11 PM, Sean Young <sean@...s.org> wrote:
> This implements the grundig-16 IR protocol.
>
> Signed-off-by: Sean Young <sean@...s.org>
> ---
> samples/bpf/Makefile | 4 +
> samples/bpf/bpf_load.c | 9 +-
> samples/bpf/grundig_decoder_kern.c | 112 ++++++++++++++++++++++
> samples/bpf/grundig_decoder_user.c | 54 +++++++++++
> tools/bpf/bpftool/prog.c | 1 +
> tools/include/uapi/linux/bpf.h | 17 +++-
> tools/testing/selftests/bpf/bpf_helpers.h | 6 ++
> 7 files changed, 200 insertions(+), 3 deletions(-)
> create mode 100644 samples/bpf/grundig_decoder_kern.c
> create mode 100644 samples/bpf/grundig_decoder_user.c
>
> diff --git a/samples/bpf/Makefile b/samples/bpf/Makefile
> index 4d6a6edd4bf6..c6fa111f103a 100644
> --- a/samples/bpf/Makefile
> +++ b/samples/bpf/Makefile
> @@ -44,6 +44,7 @@ hostprogs-y += xdp_monitor
> hostprogs-y += xdp_rxq_info
> hostprogs-y += syscall_tp
> hostprogs-y += cpustat
> +hostprogs-y += grundig_decoder
>
> # Libbpf dependencies
> LIBBPF := ../../tools/lib/bpf/bpf.o ../../tools/lib/bpf/nlattr.o
> @@ -95,6 +96,7 @@ xdp_monitor-objs := bpf_load.o $(LIBBPF) xdp_monitor_user.o
> xdp_rxq_info-objs := bpf_load.o $(LIBBPF) xdp_rxq_info_user.o
> syscall_tp-objs := bpf_load.o $(LIBBPF) syscall_tp_user.o
> cpustat-objs := bpf_load.o $(LIBBPF) cpustat_user.o
> +grundig_decoder-objs := bpf_load.o $(LIBBPF) grundig_decoder_user.o
>
> # Tell kbuild to always build the programs
> always := $(hostprogs-y)
> @@ -148,6 +150,7 @@ always += xdp_rxq_info_kern.o
> always += xdp2skb_meta_kern.o
> always += syscall_tp_kern.o
> always += cpustat_kern.o
> +always += grundig_decoder_kern.o
>
> HOSTCFLAGS += -I$(objtree)/usr/include
> HOSTCFLAGS += -I$(srctree)/tools/lib/
> @@ -193,6 +196,7 @@ HOSTLOADLIBES_xdp_monitor += -lelf
> HOSTLOADLIBES_xdp_rxq_info += -lelf
> HOSTLOADLIBES_syscall_tp += -lelf
> HOSTLOADLIBES_cpustat += -lelf
> +HOSTLOADLIBES_grundig_decoder += -lelf
>
> # Allows pointing LLC/CLANG to a LLVM backend with bpf support, redefine on cmdline:
> # make samples/bpf/ LLC=~/git/llvm/build/bin/llc CLANG=~/git/llvm/build/bin/clang
> diff --git a/samples/bpf/bpf_load.c b/samples/bpf/bpf_load.c
> index bebe4188b4b3..0fd389e95bb9 100644
> --- a/samples/bpf/bpf_load.c
> +++ b/samples/bpf/bpf_load.c
> @@ -69,6 +69,7 @@ static int load_and_attach(const char *event, struct bpf_insn *prog, int size)
> bool is_sockops = strncmp(event, "sockops", 7) == 0;
> bool is_sk_skb = strncmp(event, "sk_skb", 6) == 0;
> bool is_sk_msg = strncmp(event, "sk_msg", 6) == 0;
> + bool is_ir_decoder = strncmp(event, "ir_decoder", 10) == 0;
> size_t insns_cnt = size / sizeof(struct bpf_insn);
> enum bpf_prog_type prog_type;
> char buf[256];
> @@ -102,6 +103,8 @@ static int load_and_attach(const char *event, struct bpf_insn *prog, int size)
> prog_type = BPF_PROG_TYPE_SK_SKB;
> } else if (is_sk_msg) {
> prog_type = BPF_PROG_TYPE_SK_MSG;
> + } else if (is_ir_decoder) {
> + prog_type = BPF_PROG_TYPE_RAWIR_DECODER;
> } else {
> printf("Unknown event '%s'\n", event);
> return -1;
> @@ -116,7 +119,8 @@ static int load_and_attach(const char *event, struct bpf_insn *prog, int size)
>
> prog_fd[prog_cnt++] = fd;
>
> - if (is_xdp || is_perf_event || is_cgroup_skb || is_cgroup_sk)
> + if (is_xdp || is_perf_event || is_cgroup_skb || is_cgroup_sk ||
> + is_ir_decoder)
> return 0;
>
> if (is_socket || is_sockops || is_sk_skb || is_sk_msg) {
> @@ -607,7 +611,8 @@ static int do_load_bpf_file(const char *path, fixup_map_cb fixup_map)
> memcmp(shname, "cgroup/", 7) == 0 ||
> memcmp(shname, "sockops", 7) == 0 ||
> memcmp(shname, "sk_skb", 6) == 0 ||
> - memcmp(shname, "sk_msg", 6) == 0) {
> + memcmp(shname, "sk_msg", 6) == 0 ||
> + memcmp(shname, "ir_decoder", 10) == 0) {
> ret = load_and_attach(shname, data->d_buf,
> data->d_size);
> if (ret != 0)
> diff --git a/samples/bpf/grundig_decoder_kern.c b/samples/bpf/grundig_decoder_kern.c
> new file mode 100644
> index 000000000000..c80f2c9cc69a
> --- /dev/null
> +++ b/samples/bpf/grundig_decoder_kern.c
> @@ -0,0 +1,112 @@
> +
> +#include <uapi/linux/bpf.h>
> +#include <uapi/linux/bpf_rcdev.h>
> +#include "bpf_helpers.h"
> +#include <linux/version.h>
> +
> +enum grundig_state {
> + STATE_INACTIVE,
> + STATE_HEADER_SPACE,
> + STATE_LEADING_PULSE,
> + STATE_BITS_SPACE,
> + STATE_BITS_PULSE,
> +};
> +
> +struct decoder_state {
> + u32 bits;
> + enum grundig_state state;
> + u32 count;
> + u32 last_space;
> +};
> +
> +struct bpf_map_def SEC("maps") decoder_state_map = {
> + .type = BPF_MAP_TYPE_ARRAY,
> + .key_size = sizeof(u32),
> + .value_size = sizeof(struct decoder_state),
> + .max_entries = 1,
> +};
> +
> +#define US_TO_NS(t) 1000*(t)
> +static inline bool eq_margin(unsigned d1, unsigned d2, unsigned margin)
> +{
> + return ((d1 > (d2 - margin)) && (d1 < (d2 + margin)));
> +}
> +
> +SEC("ir_decoder/grundig_decoder")
> +int bpf_decoder(struct ir_raw_event *raw)
> +{
> + u32 key = 0;
> + struct decoder_state init = {};
> +
> + struct decoder_state *s = bpf_map_lookup_elem(&decoder_state_map, &key);
> +
> + if (!s)
> + s = &init;
> +
> + if (raw->carrier_report) {
> + // ignore
> + } else if (raw->reset) {
> + s->state = STATE_INACTIVE;
> + } else if (s->state == STATE_INACTIVE) {
> + if (raw->pulse && eq_margin(US_TO_NS(900), raw->duration, US_TO_NS(100))) {
> + s->bits = 0;
> + s->state = STATE_HEADER_SPACE;
> + s->count = 0;
> + }
> + } else if (s->state == STATE_HEADER_SPACE) {
> + if (!raw->pulse && eq_margin(US_TO_NS(2900), raw->duration, US_TO_NS(200)))
> + s->state = STATE_LEADING_PULSE;
> + else
> + s->state = STATE_INACTIVE;
> + } else if (s->state == STATE_LEADING_PULSE) {
> + if (raw->pulse && eq_margin(US_TO_NS(1300), raw->duration, US_TO_NS(100)))
> + s->state = STATE_BITS_SPACE;
> + else
> + s->state = STATE_INACTIVE;
> + } else if (s->state == STATE_BITS_SPACE) {
> + s->last_space = raw->duration;
> + s->state = STATE_BITS_PULSE;
> + } else if (s->state == STATE_BITS_PULSE) {
> + int t = -1;
> + if (eq_margin(s->last_space, US_TO_NS(472), US_TO_NS(150)) &&
> + eq_margin(raw->duration, US_TO_NS(583), US_TO_NS(150)))
> + t = 0;
> + if (eq_margin(s->last_space, US_TO_NS(1139), US_TO_NS(150)) &&
> + eq_margin(raw->duration, US_TO_NS(583), US_TO_NS(150)))
> + t = 1;
> + if (eq_margin(s->last_space, US_TO_NS(1806), US_TO_NS(150)) &&
> + eq_margin(raw->duration, US_TO_NS(583), US_TO_NS(150)))
> + t = 2;
> + if (eq_margin(s->last_space, US_TO_NS(2200), US_TO_NS(150)) &&
> + eq_margin(raw->duration, US_TO_NS(1139), US_TO_NS(150)))
> + t = 3;
> + if (t < 0) {
> + s->state = STATE_INACTIVE;
> + } else {
> + s->bits <<= 2;
> + switch (t) {
> + case 3: s->bits |= 0; break;
> + case 2: s->bits |= 3; break;
> + case 1: s->bits |= 2; break;
> + case 0: s->bits |= 1; break;
> + }
> + s->count += 2;
> + if (s->count == 16) {
> + bpf_rc_keydown(raw, 0x40, s->bits, 0);
> + s->state = STATE_INACTIVE;
> + } else {
> + s->state = STATE_BITS_SPACE;
> + }
> + }
> + }
> +
> + if (s == &init)
> + bpf_map_update_elem(&decoder_state_map, &key, s, BPF_NOEXIST);
> +
> + return 0;
> +}
> +
> +char _license[] SEC("license") = "GPL";
> +
> +u32 _version SEC("version") = LINUX_VERSION_CODE;
> +
> diff --git a/samples/bpf/grundig_decoder_user.c b/samples/bpf/grundig_decoder_user.c
> new file mode 100644
> index 000000000000..61e8ee5f73ee
> --- /dev/null
> +++ b/samples/bpf/grundig_decoder_user.c
> @@ -0,0 +1,54 @@
> +
> +#include <linux/bpf.h>
> +#include <assert.h>
> +#include <errno.h>
> +#include <signal.h>
> +#include <stdio.h>
> +#include <stdlib.h>
> +#include <stdbool.h>
> +#include <string.h>
> +#include <unistd.h>
> +#include <libgen.h>
> +#include <sys/resource.h>
> +#include <sys/types.h>
> +#include <sys/stat.h>
> +#include <fcntl.h>
> +
> +#include "bpf_load.h"
> +#include "bpf_util.h"
> +#include "libbpf.h"
> +
> +int main(int argc, char **argv)
> +{
> + char filename[256];
> + int ret, lircfd;
> +
> + if (argc != 2) {
> + printf("Usage: %s /dev/lircN\n", argv[0]);
Looks like the test requires /dev/lircN device. Is there any easy way
to test it?
Also, looks like the program does not depend on any kernel headers,
maybe it can be
moved to tools/testing/selftests/bpf/? There are testbot to run those
tests regularly.
> + return 2;
> + }
> +
> + snprintf(filename, sizeof(filename), "%s_kern.o", argv[0]);
> +
> + if (load_bpf_file(filename)) {
> + printf("%s", bpf_log_buf);
> + return 1;
> + }
> +
> + lircfd = open(argv[1], O_RDWR);
> + if (lircfd == -1) {
> + printf("failed to open lirc device %s: %m\n", argv[1]);
> + return 1;
> + }
> +
> + ret = bpf_prog_attach(prog_fd[0], lircfd, BPF_RAWIR_DECODER, 0);
> + if (ret) {
> + printf("Failed to attach bpf to lirc device: %m\n");
> + return 1;
> + }
> +
> + printf("Grundig IR decoder loaded and attached. Hit any key to stop\n");
> + getchar();
> +
> + return 0;
> +}
> diff --git a/tools/bpf/bpftool/prog.c b/tools/bpf/bpftool/prog.c
> index f7a810897eac..ae1c26df212d 100644
> --- a/tools/bpf/bpftool/prog.c
> +++ b/tools/bpf/bpftool/prog.c
> @@ -68,6 +68,7 @@ static const char * const prog_type_name[] = {
> [BPF_PROG_TYPE_SOCK_OPS] = "sock_ops",
> [BPF_PROG_TYPE_SK_SKB] = "sk_skb",
> [BPF_PROG_TYPE_CGROUP_DEVICE] = "cgroup_device",
> + [BPF_PROG_TYPE_RAWIR_DECODER] = "ir_decoder",
> };
>
> static void print_boot_time(__u64 nsecs, char *buf, unsigned int size)
> diff --git a/tools/include/uapi/linux/bpf.h b/tools/include/uapi/linux/bpf.h
> index c5ec89732a8d..d9740599adf6 100644
> --- a/tools/include/uapi/linux/bpf.h
> +++ b/tools/include/uapi/linux/bpf.h
> @@ -137,6 +137,7 @@ enum bpf_prog_type {
> BPF_PROG_TYPE_SK_MSG,
> BPF_PROG_TYPE_RAW_TRACEPOINT,
> BPF_PROG_TYPE_CGROUP_SOCK_ADDR,
> + BPF_PROG_TYPE_RAWIR_DECODER,
> };
>
> enum bpf_attach_type {
> @@ -154,6 +155,7 @@ enum bpf_attach_type {
> BPF_CGROUP_INET6_CONNECT,
> BPF_CGROUP_INET4_POST_BIND,
> BPF_CGROUP_INET6_POST_BIND,
> + BPF_RAWIR_DECODER,
> __MAX_BPF_ATTACH_TYPE
> };
>
> @@ -755,6 +757,17 @@ union bpf_attr {
> * @addr: pointer to struct sockaddr to bind socket to
> * @addr_len: length of sockaddr structure
> * Return: 0 on success or negative error code
> + *
> + * int bpf_rc_keydown(ctx, protocol, scancode, toggle)
> + * Report decoded scancode with toggle value
> + * @ctx: pointer to ctx
> + * @protocol: decoded protocol
> + * @scancode: decoded scancode
> + * @toggle: set to 1 if button was toggled, else 0
> + *
> + * int bpf_rc_repeat(ctx)
> + * Repeat the last decoded scancode
> + * @ctx: pointer to ctx
> */
> #define __BPF_FUNC_MAPPER(FN) \
> FN(unspec), \
> @@ -821,7 +834,9 @@ union bpf_attr {
> FN(msg_apply_bytes), \
> FN(msg_cork_bytes), \
> FN(msg_pull_data), \
> - FN(bind),
> + FN(bind), \
> + FN(rc_repeat), \
> + FN(rc_keydown),
>
> /* integer value in 'imm' field of BPF_CALL instruction selects which helper
> * function eBPF program intends to call
> diff --git a/tools/testing/selftests/bpf/bpf_helpers.h b/tools/testing/selftests/bpf/bpf_helpers.h
> index d8223d99f96d..4bf23d3dfc33 100644
> --- a/tools/testing/selftests/bpf/bpf_helpers.h
> +++ b/tools/testing/selftests/bpf/bpf_helpers.h
> @@ -96,6 +96,12 @@ static int (*bpf_msg_pull_data)(void *ctx, int start, int end, int flags) =
> (void *) BPF_FUNC_msg_pull_data;
> static int (*bpf_bind)(void *ctx, void *addr, int addr_len) =
> (void *) BPF_FUNC_bind;
> +static int (*bpf_rc_repeat)(void *ctx) =
> + (void *) BPF_FUNC_rc_repeat;
> +static int (*bpf_rc_keydown)(void *ctx, unsigned protocol, unsigned scancode,
> + unsigned toggle) =
> + (void *) BPF_FUNC_rc_keydown;
> +
>
> /* llvm builtin functions that eBPF C program may use to
> * emit BPF_LD_ABS and BPF_LD_IND instructions
> --
> 2.17.0
>
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