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33f0c47b BG |
1 | // SPDX-License-Identifier: GPL-2.0-only |
2 | /* | |
3 | * gpio-watch - monitor unrequested lines for property changes using the | |
4 | * character device | |
5 | * | |
6 | * Copyright (C) 2019 BayLibre SAS | |
7 | * Author: Bartosz Golaszewski <bgolaszewski@baylibre.com> | |
8 | */ | |
9 | ||
10 | #include <ctype.h> | |
11 | #include <errno.h> | |
12 | #include <fcntl.h> | |
1fc7c1ef | 13 | #include <inttypes.h> |
33f0c47b BG |
14 | #include <linux/gpio.h> |
15 | #include <poll.h> | |
16 | #include <stdbool.h> | |
17 | #include <stdio.h> | |
18 | #include <stdlib.h> | |
19 | #include <string.h> | |
20 | #include <sys/ioctl.h> | |
21 | #include <unistd.h> | |
22 | ||
23 | int main(int argc, char **argv) | |
24 | { | |
e86a863b KG |
25 | struct gpio_v2_line_info_changed chg; |
26 | struct gpio_v2_line_info req; | |
33f0c47b BG |
27 | struct pollfd pfd; |
28 | int fd, i, j, ret; | |
29 | char *event, *end; | |
30 | ssize_t rd; | |
31 | ||
32 | if (argc < 3) | |
33 | goto err_usage; | |
34 | ||
35 | fd = open(argv[1], O_RDWR | O_CLOEXEC); | |
36 | if (fd < 0) { | |
37 | perror("unable to open gpiochip"); | |
38 | return EXIT_FAILURE; | |
39 | } | |
40 | ||
41 | for (i = 0, j = 2; i < argc - 2; i++, j++) { | |
42 | memset(&req, 0, sizeof(req)); | |
43 | ||
e86a863b | 44 | req.offset = strtoul(argv[j], &end, 0); |
33f0c47b BG |
45 | if (*end != '\0') |
46 | goto err_usage; | |
47 | ||
e86a863b | 48 | ret = ioctl(fd, GPIO_V2_GET_LINEINFO_WATCH_IOCTL, &req); |
33f0c47b BG |
49 | if (ret) { |
50 | perror("unable to set up line watch"); | |
51 | return EXIT_FAILURE; | |
52 | } | |
53 | } | |
54 | ||
55 | pfd.fd = fd; | |
56 | pfd.events = POLLIN | POLLPRI; | |
57 | ||
58 | for (;;) { | |
59 | ret = poll(&pfd, 1, 5000); | |
60 | if (ret < 0) { | |
61 | perror("error polling the linechanged fd"); | |
62 | return EXIT_FAILURE; | |
63 | } else if (ret > 0) { | |
64 | memset(&chg, 0, sizeof(chg)); | |
65 | rd = read(pfd.fd, &chg, sizeof(chg)); | |
66 | if (rd < 0 || rd != sizeof(chg)) { | |
67 | if (rd != sizeof(chg)) | |
68 | errno = EIO; | |
69 | ||
70 | perror("error reading line change event"); | |
71 | return EXIT_FAILURE; | |
72 | } | |
73 | ||
74 | switch (chg.event_type) { | |
e86a863b | 75 | case GPIO_V2_LINE_CHANGED_REQUESTED: |
33f0c47b BG |
76 | event = "requested"; |
77 | break; | |
e86a863b | 78 | case GPIO_V2_LINE_CHANGED_RELEASED: |
33f0c47b BG |
79 | event = "released"; |
80 | break; | |
e86a863b | 81 | case GPIO_V2_LINE_CHANGED_CONFIG: |
33f0c47b BG |
82 | event = "config changed"; |
83 | break; | |
84 | default: | |
85 | fprintf(stderr, | |
86 | "invalid event type received from the kernel\n"); | |
87 | return EXIT_FAILURE; | |
88 | } | |
89 | ||
1fc7c1ef KG |
90 | printf("line %u: %s at %" PRIu64 "\n", |
91 | chg.info.offset, event, (uint64_t)chg.timestamp_ns); | |
33f0c47b BG |
92 | } |
93 | } | |
94 | ||
95 | return 0; | |
96 | ||
97 | err_usage: | |
98 | printf("%s: <gpiochip> <line0> <line1> ...\n", argv[0]); | |
99 | return EXIT_FAILURE; | |
100 | } |