tools/gpio: add the gpio-event-mon tool

CC = $(CROSS_COMPILE)gcc

CFLAGS += -O2 -Wall -g -D_GNU_SOURCE

all: lsgpio gpio-hammer

all: lsgpio gpio-hammer gpio-event-mon

lsgpio: lsgpio.o gpio-utils.o

gpio-hammer: gpio-hammer.o gpio-utils.o

gpio-event-mon: gpio-event-mon.o gpio-utils.o

%.o: %.c gpio-utils.h

.PHONY: clean

clean:

	rm -f *.o lsgpio gpio-hammer

	rm -f *.o lsgpio gpio-hammer gpio-event-mon

/*

 * gpio-hammer - example swiss army knife to shake GPIO lines on a system

 *

 * Copyright (C) 2016 Linus Walleij

 *

 * This program is free software; you can redistribute it and/or modify it

 * under the terms of the GNU General Public License version 2 as published by

 * the Free Software Foundation.

 *

 * Usage:

 *	gpio-event-mon -n <device-name> -o <offset>

 */

#include <unistd.h>

#include <stdlib.h>

#include <stdbool.h>

#include <stdio.h>

#include <dirent.h>

#include <errno.h>

#include <string.h>

#include <poll.h>

#include <fcntl.h>

#include <getopt.h>

#include <inttypes.h>

#include <sys/ioctl.h>

#include <linux/gpio.h>

int monitor_device(const char *device_name,

		   unsigned int line,

		   u_int32_t handleflags,

		   u_int32_t eventflags,

		   unsigned int loops)

{

	struct gpioevent_request req;

	struct gpiohandle_data data;

	char *chrdev_name;

	int fd;

	int ret;

	int i = 0;

	ret = asprintf(&chrdev_name, "/dev/%s", device_name);

	if (ret < 0)

		return -ENOMEM;

	fd = open(chrdev_name, 0);

	if (fd == -1) {

		ret = -errno;

		fprintf(stderr, "Failed to open %s\n", chrdev_name);

		goto exit_close_error;

	}

	req.lineoffset = line;

	req.handleflags = handleflags;

	req.eventflags = eventflags;

	strcpy(req.consumer_label, "gpio-event-mon");

	ret = ioctl(fd, GPIO_GET_LINEEVENT_IOCTL, &req);

	if (ret == -1) {

		ret = -errno;

		fprintf(stderr, "Failed to issue GET EVENT "

			"IOCTL (%d)\n",

			ret);

		goto exit_close_error;

	}

	/* Read initial states */

	ret = ioctl(req.fd, GPIOHANDLE_GET_LINE_VALUES_IOCTL, &data);

	if (ret == -1) {

		ret = -errno;

		fprintf(stderr, "Failed to issue GPIOHANDLE GET LINE "

			"VALUES IOCTL (%d)\n",

			ret);

		goto exit_close_error;

	}

	fprintf(stdout, "Monitoring line %d on %s\n", line, device_name);

	fprintf(stdout, "Initial line value: %d\n", data.values[0]);

	while (1) {

		struct gpioevent_data event;

		ret = read(req.fd, &event, sizeof(event));

		if (ret == -1) {

			if (errno == -EAGAIN) {

				fprintf(stderr, "nothing available\n");

				continue;

			} else {

				ret = -errno;

				fprintf(stderr, "Failed to read event (%d)\n",

					ret);

				break;

			}

		}

		if (ret != sizeof(event)) {

			fprintf(stderr, "Reading event failed\n");

			ret = -EIO;

			break;

		}

		fprintf(stdout, "GPIO EVENT %" PRIu64 ": ", event.timestamp);

		switch (event.id) {

		case GPIOEVENT_EVENT_RISING_EDGE:

			fprintf(stdout, "rising edge");

			break;

		case GPIOEVENT_EVENT_FALLING_EDGE:

			fprintf(stdout, "falling edge");

			break;

		default:

			fprintf(stdout, "unknown event");

		}

		fprintf(stdout, "\n");

		i++;

		if (i == loops)

			break;

	}

exit_close_error:

	if (close(fd) == -1)

		perror("Failed to close GPIO character device file");

	free(chrdev_name);

	return ret;

}

void print_usage(void)

{

	fprintf(stderr, "Usage: gpio-event-mon [options]...\n"

		"Listen to events on GPIO lines, 0->1 1->0\n"

		"  -n <name>  Listen on GPIOs on a named device (must be stated)\n"

		"  -o <n>     Offset to monitor\n"

		"  -d         Set line as open drain\n"

		"  -s         Set line as open source\n"

		"  -r         Listen for rising edges\n"

		"  -f         Listen for falling edges\n"

		" [-c <n>]    Do <n> loops (optional, infinite loop if not stated)\n"

		"  -?         This helptext\n"

		"\n"

		"Example:\n"

		"gpio-event-mon -n gpiochip0 -o 4 -r -f\n"

	);

}

int main(int argc, char **argv)

{

	const char *device_name = NULL;

	unsigned int line = -1;

	unsigned int loops = 0;

	u_int32_t handleflags = GPIOHANDLE_REQUEST_INPUT;

	u_int32_t eventflags = 0;

	int c;

	while ((c = getopt(argc, argv, "c:n:o:dsrf?")) != -1) {

		switch (c) {

		case 'c':

			loops = strtoul(optarg, NULL, 10);

			break;

		case 'n':

			device_name = optarg;

			break;

		case 'o':

			line = strtoul(optarg, NULL, 10);

			break;

		case 'd':

			handleflags |= GPIOHANDLE_REQUEST_OPEN_DRAIN;

			break;

		case 's':

			handleflags |= GPIOHANDLE_REQUEST_OPEN_SOURCE;

			break;

		case 'r':

			eventflags |= GPIOEVENT_REQUEST_RISING_EDGE;

			break;

		case 'f':

			eventflags |= GPIOEVENT_REQUEST_FALLING_EDGE;

			break;

		case '?':

			print_usage();

			return -1;

		}

	}

	if (!device_name || line == -1) {

		print_usage();

		return -1;

	}

	if (!eventflags) {

		printf("No flags specified, listening on both rising and "

		       "falling edges\n");

		eventflags = GPIOEVENT_REQUEST_BOTH_EDGES;

	}

	return monitor_device(device_name, line, handleflags,

			      eventflags, loops);

}