xref: /openbmc/linux/tools/gpio/gpio-event-mon.c (revision d0e22329)
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 
30 int 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 
120 exit_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 
127 void 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 
145 int 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