1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3  * gpio-event-mon - monitor GPIO line events from userspace
4  *
5  * Copyright (C) 2016 Linus Walleij
6  *
7  * Usage:
8  *	gpio-event-mon -n <device-name> -o <offset>
9  */
10 
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 #include "gpio-utils.h"
27 
monitor_device(const char * device_name,unsigned int * lines,unsigned int num_lines,struct gpio_v2_line_config * config,unsigned int loops)28 int monitor_device(const char *device_name,
29 		   unsigned int *lines,
30 		   unsigned int num_lines,
31 		   struct gpio_v2_line_config *config,
32 		   unsigned int loops)
33 {
34 	struct gpio_v2_line_values values;
35 	char *chrdev_name;
36 	int cfd, lfd;
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 	cfd = open(chrdev_name, 0);
45 	if (cfd == -1) {
46 		ret = -errno;
47 		fprintf(stderr, "Failed to open %s\n", chrdev_name);
48 		goto exit_free_name;
49 	}
50 
51 	ret = gpiotools_request_line(device_name, lines, num_lines, config,
52 				     "gpio-event-mon");
53 	if (ret < 0)
54 		goto exit_device_close;
55 	else
56 		lfd = ret;
57 
58 	/* Read initial states */
59 	values.mask = 0;
60 	values.bits = 0;
61 	for (i = 0; i < num_lines; i++)
62 		gpiotools_set_bit(&values.mask, i);
63 	ret = gpiotools_get_values(lfd, &values);
64 	if (ret < 0) {
65 		fprintf(stderr,
66 			"Failed to issue GPIO LINE GET VALUES IOCTL (%d)\n",
67 			ret);
68 		goto exit_line_close;
69 	}
70 
71 	if (num_lines == 1) {
72 		fprintf(stdout, "Monitoring line %d on %s\n", lines[0], device_name);
73 		fprintf(stdout, "Initial line value: %d\n",
74 			gpiotools_test_bit(values.bits, 0));
75 	} else {
76 		fprintf(stdout, "Monitoring lines %d", lines[0]);
77 		for (i = 1; i < num_lines - 1; i++)
78 			fprintf(stdout, ", %d", lines[i]);
79 		fprintf(stdout, " and %d on %s\n", lines[i], device_name);
80 		fprintf(stdout, "Initial line values: %d",
81 			gpiotools_test_bit(values.bits, 0));
82 		for (i = 1; i < num_lines - 1; i++)
83 			fprintf(stdout, ", %d",
84 				gpiotools_test_bit(values.bits, i));
85 		fprintf(stdout, " and %d\n",
86 			gpiotools_test_bit(values.bits, i));
87 	}
88 
89 	i = 0;
90 	while (1) {
91 		struct gpio_v2_line_event event;
92 
93 		ret = read(lfd, &event, sizeof(event));
94 		if (ret == -1) {
95 			if (errno == -EAGAIN) {
96 				fprintf(stderr, "nothing available\n");
97 				continue;
98 			} else {
99 				ret = -errno;
100 				fprintf(stderr, "Failed to read event (%d)\n",
101 					ret);
102 				break;
103 			}
104 		}
105 
106 		if (ret != sizeof(event)) {
107 			fprintf(stderr, "Reading event failed\n");
108 			ret = -EIO;
109 			break;
110 		}
111 		fprintf(stdout, "GPIO EVENT at %" PRIu64 " on line %d (%d|%d) ",
112 			(uint64_t)event.timestamp_ns, event.offset, event.line_seqno,
113 			event.seqno);
114 		switch (event.id) {
115 		case GPIO_V2_LINE_EVENT_RISING_EDGE:
116 			fprintf(stdout, "rising edge");
117 			break;
118 		case GPIO_V2_LINE_EVENT_FALLING_EDGE:
119 			fprintf(stdout, "falling edge");
120 			break;
121 		default:
122 			fprintf(stdout, "unknown event");
123 		}
124 		fprintf(stdout, "\n");
125 
126 		i++;
127 		if (i == loops)
128 			break;
129 	}
130 
131 exit_line_close:
132 	if (close(lfd) == -1)
133 		perror("Failed to close line file");
134 exit_device_close:
135 	if (close(cfd) == -1)
136 		perror("Failed to close GPIO character device file");
137 exit_free_name:
138 	free(chrdev_name);
139 	return ret;
140 }
141 
print_usage(void)142 void print_usage(void)
143 {
144 	fprintf(stderr, "Usage: gpio-event-mon [options]...\n"
145 		"Listen to events on GPIO lines, 0->1 1->0\n"
146 		"  -n <name>  Listen on GPIOs on a named device (must be stated)\n"
147 		"  -o <n>     Offset of line to monitor (may be repeated)\n"
148 		"  -d         Set line as open drain\n"
149 		"  -s         Set line as open source\n"
150 		"  -r         Listen for rising edges\n"
151 		"  -f         Listen for falling edges\n"
152 		"  -w         Report the wall-clock time for events\n"
153 		"  -t         Report the hardware timestamp for events\n"
154 		"  -b <n>     Debounce the line with period n microseconds\n"
155 		" [-c <n>]    Do <n> loops (optional, infinite loop if not stated)\n"
156 		"  -?         This helptext\n"
157 		"\n"
158 		"Example:\n"
159 		"gpio-event-mon -n gpiochip0 -o 4 -r -f -b 10000\n"
160 	);
161 }
162 
163 #define EDGE_FLAGS \
164 	(GPIO_V2_LINE_FLAG_EDGE_RISING | \
165 	 GPIO_V2_LINE_FLAG_EDGE_FALLING)
166 
main(int argc,char ** argv)167 int main(int argc, char **argv)
168 {
169 	const char *device_name = NULL;
170 	unsigned int lines[GPIO_V2_LINES_MAX];
171 	unsigned int num_lines = 0;
172 	unsigned int loops = 0;
173 	struct gpio_v2_line_config config;
174 	int c, attr, i;
175 	unsigned long debounce_period_us = 0;
176 
177 	memset(&config, 0, sizeof(config));
178 	config.flags = GPIO_V2_LINE_FLAG_INPUT;
179 	while ((c = getopt(argc, argv, "c:n:o:b:dsrfwt?")) != -1) {
180 		switch (c) {
181 		case 'c':
182 			loops = strtoul(optarg, NULL, 10);
183 			break;
184 		case 'n':
185 			device_name = optarg;
186 			break;
187 		case 'o':
188 			if (num_lines >= GPIO_V2_LINES_MAX) {
189 				print_usage();
190 				return -1;
191 			}
192 			lines[num_lines] = strtoul(optarg, NULL, 10);
193 			num_lines++;
194 			break;
195 		case 'b':
196 			debounce_period_us = strtoul(optarg, NULL, 10);
197 			break;
198 		case 'd':
199 			config.flags |= GPIO_V2_LINE_FLAG_OPEN_DRAIN;
200 			break;
201 		case 's':
202 			config.flags |= GPIO_V2_LINE_FLAG_OPEN_SOURCE;
203 			break;
204 		case 'r':
205 			config.flags |= GPIO_V2_LINE_FLAG_EDGE_RISING;
206 			break;
207 		case 'f':
208 			config.flags |= GPIO_V2_LINE_FLAG_EDGE_FALLING;
209 			break;
210 		case 'w':
211 			config.flags |= GPIO_V2_LINE_FLAG_EVENT_CLOCK_REALTIME;
212 			break;
213 		case 't':
214 			config.flags |= GPIO_V2_LINE_FLAG_EVENT_CLOCK_HTE;
215 			break;
216 		case '?':
217 			print_usage();
218 			return -1;
219 		}
220 	}
221 
222 	if (debounce_period_us) {
223 		attr = config.num_attrs;
224 		config.num_attrs++;
225 		for (i = 0; i < num_lines; i++)
226 			gpiotools_set_bit(&config.attrs[attr].mask, i);
227 		config.attrs[attr].attr.id = GPIO_V2_LINE_ATTR_ID_DEBOUNCE;
228 		config.attrs[attr].attr.debounce_period_us = debounce_period_us;
229 	}
230 
231 	if (!device_name || num_lines == 0) {
232 		print_usage();
233 		return -1;
234 	}
235 	if (!(config.flags & EDGE_FLAGS)) {
236 		printf("No flags specified, listening on both rising and "
237 		       "falling edges\n");
238 		config.flags |= EDGE_FLAGS;
239 	}
240 	return monitor_device(device_name, lines, num_lines, &config, loops);
241 }
242