linux/tools/testing/selftests/bpf/test_lirc_mode2_user.c

// SPDX-License-Identifier: GPL-2.0
// test ir decoder
//
// Copyright (C) 2018 Sean Young <sean@mess.org>

// A lirc chardev is a device representing a consumer IR (cir) device which
// can receive infrared signals from remote control and/or transmit IR.
//
// IR is sent as a series of pulses and space somewhat like morse code. The
// BPF program can decode this into scancodes so that rc-core can translate
// this into input key codes using the rc keymap.
//
// This test works by sending IR over rc-loopback, so the IR is processed by
// BPF and then decoded into scancodes. The lirc chardev must be the one
// associated with rc-loopback, see the output of ir-keytable(1).
//
// The following CONFIG options must be enabled for the test to succeed:
// CONFIG_RC_CORE=y
// CONFIG_BPF_RAWIR_EVENT=y
// CONFIG_RC_LOOPBACK=y

// Steps:
// 1. Open the /dev/lircN device for rc-loopback (given on command line)
// 2. Attach bpf_lirc_mode2 program which decodes some IR.
// 3. Send some IR to the same IR device; since it is loopback, this will
//    end up in the bpf program
// 4. bpf program should decode IR and report keycode
// 5. We can read keycode from same /dev/lirc device

#include <linux/bpf.h>
#include <linux/lirc.h>
#include <errno.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <poll.h>
#include <sys/types.h>
#include <sys/ioctl.h>
#include <sys/stat.h>
#include <fcntl.h>

#include "bpf_util.h"
#include <bpf/bpf.h>
#include <bpf/libbpf.h>

int main(int argc, char **argv)
{
	struct bpf_object *obj;
	int ret, lircfd, progfd, mode;
	int testir = 0x1dead;
	u32 prog_ids[10], prog_flags[10], prog_cnt;

	if (argc != 2) {
		printf("Usage: %s /dev/lircN\n", argv[0]);
		return 2;
	}

	ret = bpf_prog_load("test_lirc_mode2_kern.o",
			    BPF_PROG_TYPE_LIRC_MODE2, &obj, &progfd);
	if (ret) {
		printf("Failed to load bpf program\n");
		return 1;
	}

	lircfd = open(argv[1], O_RDWR | O_NONBLOCK);
	if (lircfd == -1) {
		printf("failed to open lirc device %s: %m\n", argv[1]);
		return 1;
	}

	/* Let's try detach it before it was ever attached */
	ret = bpf_prog_detach2(progfd, lircfd, BPF_LIRC_MODE2);
	if (ret != -1 || errno != ENOENT) {
		printf("bpf_prog_detach2 not attached should fail: %m\n");
		return 1;
	}

	mode = LIRC_MODE_SCANCODE;
	if (ioctl(lircfd, LIRC_SET_REC_MODE, &mode)) {
		printf("failed to set rec mode: %m\n");
		return 1;
	}

	prog_cnt = 10;
	ret = bpf_prog_query(lircfd, BPF_LIRC_MODE2, 0, prog_flags, prog_ids,
			     &prog_cnt);
	if (ret) {
		printf("Failed to query bpf programs on lirc device: %m\n");
		return 1;
	}

	if (prog_cnt != 0) {
		printf("Expected nothing to be attached\n");
		return 1;
	}

	ret = bpf_prog_attach(progfd, lircfd, BPF_LIRC_MODE2, 0);
	if (ret) {
		printf("Failed to attach bpf to lirc device: %m\n");
		return 1;
	}

	/* Write raw IR */
	ret = write(lircfd, &testir, sizeof(testir));
	if (ret != sizeof(testir)) {
		printf("Failed to send test IR message: %m\n");
		return 1;
	}

	struct pollfd pfd = { .fd = lircfd, .events = POLLIN };
	struct lirc_scancode lsc;

	poll(&pfd, 1, 100);

	/* Read decoded IR */
	ret = read(lircfd, &lsc, sizeof(lsc));
	if (ret != sizeof(lsc)) {
		printf("Failed to read decoded IR: %m\n");
		return 1;
	}

	if (lsc.scancode != 0xdead || lsc.rc_proto != 64) {
		printf("Incorrect scancode decoded\n");
		return 1;
	}

	prog_cnt = 10;
	ret = bpf_prog_query(lircfd, BPF_LIRC_MODE2, 0, prog_flags, prog_ids,
			     &prog_cnt);
	if (ret) {
		printf("Failed to query bpf programs on lirc device: %m\n");
		return 1;
	}

	if (prog_cnt != 1) {
		printf("Expected one program to be attached\n");
		return 1;
	}

	/* Let's try detaching it now it is actually attached */
	ret = bpf_prog_detach2(progfd, lircfd, BPF_LIRC_MODE2);
	if (ret) {
		printf("bpf_prog_detach2: returned %m\n");
		return 1;
	}

	return 0;
}