1
2
3
4
5
6
7
8
9
10
11
12
13
14#include <unistd.h>
15#include <stdlib.h>
16#include <stdbool.h>
17#include <stdio.h>
18#include <dirent.h>
19#include <errno.h>
20#include <string.h>
21#include <poll.h>
22#include <fcntl.h>
23#include <getopt.h>
24#include <inttypes.h>
25#include <sys/ioctl.h>
26#include <linux/gpio.h>
27
28int monitor_device(const char *device_name,
29 unsigned int line,
30 u_int32_t handleflags,
31 u_int32_t eventflags,
32 unsigned int loops)
33{
34 struct gpioevent_request req;
35 struct gpiohandle_data data;
36 char *chrdev_name;
37 int fd;
38 int ret;
39 int i = 0;
40
41 ret = asprintf(&chrdev_name, "/dev/%s", device_name);
42 if (ret < 0)
43 return -ENOMEM;
44
45 fd = open(chrdev_name, 0);
46 if (fd == -1) {
47 ret = -errno;
48 fprintf(stderr, "Failed to open %s\n", chrdev_name);
49 goto exit_close_error;
50 }
51
52 req.lineoffset = line;
53 req.handleflags = handleflags;
54 req.eventflags = eventflags;
55 strcpy(req.consumer_label, "gpio-event-mon");
56
57 ret = ioctl(fd, GPIO_GET_LINEEVENT_IOCTL, &req);
58 if (ret == -1) {
59 ret = -errno;
60 fprintf(stderr, "Failed to issue GET EVENT "
61 "IOCTL (%d)\n",
62 ret);
63 goto exit_close_error;
64 }
65
66
67 ret = ioctl(req.fd, GPIOHANDLE_GET_LINE_VALUES_IOCTL, &data);
68 if (ret == -1) {
69 ret = -errno;
70 fprintf(stderr, "Failed to issue GPIOHANDLE GET LINE "
71 "VALUES IOCTL (%d)\n",
72 ret);
73 goto exit_close_error;
74 }
75
76 fprintf(stdout, "Monitoring line %d on %s\n", line, device_name);
77 fprintf(stdout, "Initial line value: %d\n", data.values[0]);
78
79 while (1) {
80 struct gpioevent_data event;
81
82 ret = read(req.fd, &event, sizeof(event));
83 if (ret == -1) {
84 if (errno == -EAGAIN) {
85 fprintf(stderr, "nothing available\n");
86 continue;
87 } else {
88 ret = -errno;
89 fprintf(stderr, "Failed to read event (%d)\n",
90 ret);
91 break;
92 }
93 }
94
95 if (ret != sizeof(event)) {
96 fprintf(stderr, "Reading event failed\n");
97 ret = -EIO;
98 break;
99 }
100 fprintf(stdout, "GPIO EVENT %" PRIu64 ": ", event.timestamp);
101 switch (event.id) {
102 case GPIOEVENT_EVENT_RISING_EDGE:
103 fprintf(stdout, "rising edge");
104 break;
105 case GPIOEVENT_EVENT_FALLING_EDGE:
106 fprintf(stdout, "falling edge");
107 break;
108 default:
109 fprintf(stdout, "unknown event");
110 }
111 fprintf(stdout, "\n");
112
113 i++;
114 if (i == loops)
115 break;
116 }
117
118exit_close_error:
119 if (close(fd) == -1)
120 perror("Failed to close GPIO character device file");
121 free(chrdev_name);
122 return ret;
123}
124
125void print_usage(void)
126{
127 fprintf(stderr, "Usage: gpio-event-mon [options]...\n"
128 "Listen to events on GPIO lines, 0->1 1->0\n"
129 " -n <name> Listen on GPIOs on a named device (must be stated)\n"
130 " -o <n> Offset to monitor\n"
131 " -d Set line as open drain\n"
132 " -s Set line as open source\n"
133 " -r Listen for rising edges\n"
134 " -f Listen for falling edges\n"
135 " [-c <n>] Do <n> loops (optional, infinite loop if not stated)\n"
136 " -? This helptext\n"
137 "\n"
138 "Example:\n"
139 "gpio-event-mon -n gpiochip0 -o 4 -r -f\n"
140 );
141}
142
143int main(int argc, char **argv)
144{
145 const char *device_name = NULL;
146 unsigned int line = -1;
147 unsigned int loops = 0;
148 u_int32_t handleflags = GPIOHANDLE_REQUEST_INPUT;
149 u_int32_t eventflags = 0;
150 int c;
151
152 while ((c = getopt(argc, argv, "c:n:o:dsrf?")) != -1) {
153 switch (c) {
154 case 'c':
155 loops = strtoul(optarg, NULL, 10);
156 break;
157 case 'n':
158 device_name = optarg;
159 break;
160 case 'o':
161 line = strtoul(optarg, NULL, 10);
162 break;
163 case 'd':
164 handleflags |= GPIOHANDLE_REQUEST_OPEN_DRAIN;
165 break;
166 case 's':
167 handleflags |= GPIOHANDLE_REQUEST_OPEN_SOURCE;
168 break;
169 case 'r':
170 eventflags |= GPIOEVENT_REQUEST_RISING_EDGE;
171 break;
172 case 'f':
173 eventflags |= GPIOEVENT_REQUEST_FALLING_EDGE;
174 break;
175 case '?':
176 print_usage();
177 return -1;
178 }
179 }
180
181 if (!device_name || line == -1) {
182 print_usage();
183 return -1;
184 }
185 if (!eventflags) {
186 printf("No flags specified, listening on both rising and "
187 "falling edges\n");
188 eventflags = GPIOEVENT_REQUEST_BOTH_EDGES;
189 }
190 return monitor_device(device_name, line, handleflags,
191 eventflags, loops);
192}
193
