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
 28int 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	while (1) {
 90		struct gpio_v2_line_event event;
 91
 92		ret = read(lfd, &event, sizeof(event));
 93		if (ret == -1) {
 94			if (errno == -EAGAIN) {
 95				fprintf(stderr, "nothing available\n");
 96				continue;
 97			} else {
 98				ret = -errno;
 99				fprintf(stderr, "Failed to read event (%d)\n",
100					ret);
101				break;
102			}
103		}
104
105		if (ret != sizeof(event)) {
106			fprintf(stderr, "Reading event failed\n");
107			ret = -EIO;
108			break;
109		}
110		fprintf(stdout, "GPIO EVENT at %" PRIu64 " on line %d (%d|%d) ",
111			(uint64_t)event.timestamp_ns, event.offset, event.line_seqno,
112			event.seqno);
113		switch (event.id) {
114		case GPIO_V2_LINE_EVENT_RISING_EDGE:
115			fprintf(stdout, "rising edge");
116			break;
117		case GPIO_V2_LINE_EVENT_FALLING_EDGE:
118			fprintf(stdout, "falling edge");
119			break;
120		default:
121			fprintf(stdout, "unknown event");
122		}
123		fprintf(stdout, "\n");
124
125		i++;
126		if (i == loops)
127			break;
128	}
129
130exit_line_close:
131	if (close(lfd) == -1)
132		perror("Failed to close line file");
133exit_device_close:
134	if (close(cfd) == -1)
135		perror("Failed to close GPIO character device file");
136exit_free_name:
137	free(chrdev_name);
138	return ret;
139}
140
141void print_usage(void)
142{
143	fprintf(stderr, "Usage: gpio-event-mon [options]...\n"
144		"Listen to events on GPIO lines, 0->1 1->0\n"
145		"  -n <name>  Listen on GPIOs on a named device (must be stated)\n"
146		"  -o <n>     Offset of line to monitor (may be repeated)\n"
147		"  -d         Set line as open drain\n"
148		"  -s         Set line as open source\n"
149		"  -r         Listen for rising edges\n"
150		"  -f         Listen for falling edges\n"
151		"  -w         Report the wall-clock time for events\n"
152		"  -b <n>     Debounce the line with period n microseconds\n"
153		" [-c <n>]    Do <n> loops (optional, infinite loop if not stated)\n"
154		"  -?         This helptext\n"
155		"\n"
156		"Example:\n"
157		"gpio-event-mon -n gpiochip0 -o 4 -r -f -b 10000\n"
158	);
159}
160
161#define EDGE_FLAGS \
162	(GPIO_V2_LINE_FLAG_EDGE_RISING | \
163	 GPIO_V2_LINE_FLAG_EDGE_FALLING)
164
165int main(int argc, char **argv)
166{
167	const char *device_name = NULL;
168	unsigned int lines[GPIO_V2_LINES_MAX];
169	unsigned int num_lines = 0;
170	unsigned int loops = 0;
171	struct gpio_v2_line_config config;
172	int c, attr, i;
173	unsigned long debounce_period_us = 0;
174
175	memset(&config, 0, sizeof(config));
176	config.flags = GPIO_V2_LINE_FLAG_INPUT;
177	while ((c = getopt(argc, argv, "c:n:o:b:dsrfw?")) != -1) {
178		switch (c) {
179		case 'c':
180			loops = strtoul(optarg, NULL, 10);
181			break;
182		case 'n':
183			device_name = optarg;
184			break;
185		case 'o':
186			if (num_lines >= GPIO_V2_LINES_MAX) {
187				print_usage();
188				return -1;
189			}
190			lines[num_lines] = strtoul(optarg, NULL, 10);
191			num_lines++;
192			break;
193		case 'b':
194			debounce_period_us = strtoul(optarg, NULL, 10);
195			break;
196		case 'd':
197			config.flags |= GPIO_V2_LINE_FLAG_OPEN_DRAIN;
198			break;
199		case 's':
200			config.flags |= GPIO_V2_LINE_FLAG_OPEN_SOURCE;
201			break;
202		case 'r':
203			config.flags |= GPIO_V2_LINE_FLAG_EDGE_RISING;
204			break;
205		case 'f':
206			config.flags |= GPIO_V2_LINE_FLAG_EDGE_FALLING;
207			break;
208		case 'w':
209			config.flags |= GPIO_V2_LINE_FLAG_EVENT_CLOCK_REALTIME;
210			break;
211		case '?':
212			print_usage();
213			return -1;
214		}
215	}
216
217	if (debounce_period_us) {
218		attr = config.num_attrs;
219		config.num_attrs++;
220		for (i = 0; i < num_lines; i++)
221			gpiotools_set_bit(&config.attrs[attr].mask, i);
222		config.attrs[attr].attr.id = GPIO_V2_LINE_ATTR_ID_DEBOUNCE;
223		config.attrs[attr].attr.debounce_period_us = debounce_period_us;
224	}
225
226	if (!device_name || num_lines == 0) {
227		print_usage();
228		return -1;
229	}
230	if (!(config.flags & EDGE_FLAGS)) {
231		printf("No flags specified, listening on both rising and "
232		       "falling edges\n");
233		config.flags |= EDGE_FLAGS;
234	}
235	return monitor_device(device_name, lines, num_lines, &config, loops);
236}