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> |
13 | #include <inttypes.h> |
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 | { |
25 | struct gpio_v2_line_info_changed chg; |
26 | struct gpio_v2_line_info req; |
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 | |
44 | req.offset = strtoul(argv[j], &end, 0); |
45 | if (*end != '\0') |
46 | goto err_usage; |
47 | |
48 | ret = ioctl(fd, GPIO_V2_GET_LINEINFO_WATCH_IOCTL, &req); |
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) { |
75 | case GPIO_V2_LINE_CHANGED_REQUESTED: |
76 | event = "requested" ; |
77 | break; |
78 | case GPIO_V2_LINE_CHANGED_RELEASED: |
79 | event = "released" ; |
80 | break; |
81 | case GPIO_V2_LINE_CHANGED_CONFIG: |
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 | |
90 | printf("line %u: %s at %" PRIu64 "\n" , |
91 | chg.info.offset, event, (uint64_t)chg.timestamp_ns); |
92 | } |
93 | } |
94 | |
95 | return 0; |
96 | |
97 | err_usage: |
98 | printf("%s: <gpiochip> <line0> <line1> ...\n" , argv[0]); |
99 | return EXIT_FAILURE; |
100 | } |
101 | |