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	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
131exit_line_close:
132	if (close(lfd) == -1)
133		perror("Failed to close line file");
134exit_device_close:
135	if (close(cfd) == -1)
136		perror("Failed to close GPIO character device file");
137exit_free_name:
138	free(chrdev_name);
139	return ret;
140}
141
142void 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
167int 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}