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
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