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