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1/*
2 * gpio-event-mon - monitor GPIO line events from userspace
3 *
4 * Copyright (C) 2016 Linus Walleij
5 *
6 * This program is free software; you can redistribute it and/or modify it
7 * under the terms of the GNU General Public License version 2 as published by
8 * the Free Software Foundation.
9 *
10 * Usage:
11 * gpio-event-mon -n <device-name> -o <offset>
12 */
13
14#include <unistd.h>
15#include <stdlib.h>
16#include <stdbool.h>
17#include <stdint.h>
18#include <stdio.h>
19#include <dirent.h>
20#include <errno.h>
21#include <string.h>
22#include <poll.h>
23#include <fcntl.h>
24#include <getopt.h>
25#include <inttypes.h>
26#include <sys/ioctl.h>
27#include <sys/types.h>
28#include <linux/gpio.h>
29
30int monitor_device(const char *device_name,
31 unsigned int line,
32 uint32_t handleflags,
33 uint32_t eventflags,
34 unsigned int loops)
35{
36 struct gpioevent_request req;
37 struct gpiohandle_data data;
38 char *chrdev_name;
39 int fd;
40 int ret;
41 int i = 0;
42
43 ret = asprintf(&chrdev_name, "/dev/%s", device_name);
44 if (ret < 0)
45 return -ENOMEM;
46
47 fd = open(chrdev_name, 0);
48 if (fd == -1) {
49 ret = -errno;
50 fprintf(stderr, "Failed to open %s\n", chrdev_name);
51 goto exit_close_error;
52 }
53
54 req.lineoffset = line;
55 req.handleflags = handleflags;
56 req.eventflags = eventflags;
57 strcpy(req.consumer_label, "gpio-event-mon");
58
59 ret = ioctl(fd, GPIO_GET_LINEEVENT_IOCTL, &req);
60 if (ret == -1) {
61 ret = -errno;
62 fprintf(stderr, "Failed to issue GET EVENT "
63 "IOCTL (%d)\n",
64 ret);
65 goto exit_close_error;
66 }
67
68 /* Read initial states */
69 ret = ioctl(req.fd, GPIOHANDLE_GET_LINE_VALUES_IOCTL, &data);
70 if (ret == -1) {
71 ret = -errno;
72 fprintf(stderr, "Failed to issue GPIOHANDLE GET LINE "
73 "VALUES IOCTL (%d)\n",
74 ret);
75 goto exit_close_error;
76 }
77
78 fprintf(stdout, "Monitoring line %d on %s\n", line, device_name);
79 fprintf(stdout, "Initial line value: %d\n", data.values[0]);
80
81 while (1) {
82 struct gpioevent_data event;
83
84 ret = read(req.fd, &event, sizeof(event));
85 if (ret == -1) {
86 if (errno == -EAGAIN) {
87 fprintf(stderr, "nothing available\n");
88 continue;
89 } else {
90 ret = -errno;
91 fprintf(stderr, "Failed to read event (%d)\n",
92 ret);
93 break;
94 }
95 }
96
97 if (ret != sizeof(event)) {
98 fprintf(stderr, "Reading event failed\n");
99 ret = -EIO;
100 break;
101 }
102 fprintf(stdout, "GPIO EVENT %llu: ", event.timestamp);
103 switch (event.id) {
104 case GPIOEVENT_EVENT_RISING_EDGE:
105 fprintf(stdout, "rising edge");
106 break;
107 case GPIOEVENT_EVENT_FALLING_EDGE:
108 fprintf(stdout, "falling edge");
109 break;
110 default:
111 fprintf(stdout, "unknown event");
112 }
113 fprintf(stdout, "\n");
114
115 i++;
116 if (i == loops)
117 break;
118 }
119
120exit_close_error:
121 if (close(fd) == -1)
122 perror("Failed to close GPIO character device file");
123 free(chrdev_name);
124 return ret;
125}
126
127void print_usage(void)
128{
129 fprintf(stderr, "Usage: gpio-event-mon [options]...\n"
130 "Listen to events on GPIO lines, 0->1 1->0\n"
131 " -n <name> Listen on GPIOs on a named device (must be stated)\n"
132 " -o <n> Offset to monitor\n"
133 " -d Set line as open drain\n"
134 " -s Set line as open source\n"
135 " -r Listen for rising edges\n"
136 " -f Listen for falling edges\n"
137 " [-c <n>] Do <n> loops (optional, infinite loop if not stated)\n"
138 " -? This helptext\n"
139 "\n"
140 "Example:\n"
141 "gpio-event-mon -n gpiochip0 -o 4 -r -f\n"
142 );
143}
144
145int main(int argc, char **argv)
146{
147 const char *device_name = NULL;
148 unsigned int line = -1;
149 unsigned int loops = 0;
150 uint32_t handleflags = GPIOHANDLE_REQUEST_INPUT;
151 uint32_t eventflags = 0;
152 int c;
153
154 while ((c = getopt(argc, argv, "c:n:o:dsrf?")) != -1) {
155 switch (c) {
156 case 'c':
157 loops = strtoul(optarg, NULL, 10);
158 break;
159 case 'n':
160 device_name = optarg;
161 break;
162 case 'o':
163 line = strtoul(optarg, NULL, 10);
164 break;
165 case 'd':
166 handleflags |= GPIOHANDLE_REQUEST_OPEN_DRAIN;
167 break;
168 case 's':
169 handleflags |= GPIOHANDLE_REQUEST_OPEN_SOURCE;
170 break;
171 case 'r':
172 eventflags |= GPIOEVENT_REQUEST_RISING_EDGE;
173 break;
174 case 'f':
175 eventflags |= GPIOEVENT_REQUEST_FALLING_EDGE;
176 break;
177 case '?':
178 print_usage();
179 return -1;
180 }
181 }
182
183 if (!device_name || line == -1) {
184 print_usage();
185 return -1;
186 }
187 if (!eventflags) {
188 printf("No flags specified, listening on both rising and "
189 "falling edges\n");
190 eventflags = GPIOEVENT_REQUEST_BOTH_EDGES;
191 }
192 return monitor_device(device_name, line, handleflags,
193 eventflags, loops);
194}
195

Warning: That file was not part of the compilation database. It may have many parsing errors.