Commit 33f0c47b authored by Bartosz Golaszewski's avatar Bartosz Golaszewski
Browse files

tools: gpio: implement gpio-watch 



Add a simple program that allows to test the new LINECHANGED_FD ioctl().

Signed-off-by: default avatarBartosz Golaszewski <bgolaszewski@baylibre.com>
Reviewed-by: default avatarAndy Shevchenko <andriy.shevchenko@linux.intel.com>
parent 51c1064e

tools/gpio/.gitignore

+1 −0
Original line number Diff line number Diff line 
gpio-event-mon

gpio-hammer

gpio-watch

lsgpio

include/linux/gpio.h

tools/gpio/Build

+1 −0
Original line number Diff line number Diff line
@@ -2,3 +2,4 @@ gpio-utils-y += gpio-utils.o 
lsgpio-y += lsgpio.o gpio-utils.o

gpio-hammer-y += gpio-hammer.o gpio-utils.o

gpio-event-mon-y += gpio-event-mon.o gpio-utils.o

gpio-watch-y += gpio-watch.o

tools/gpio/Makefile

+10 −1
Original line number Diff line number Diff line
@@ -18,7 +18,7 @@ MAKEFLAGS += -r 


override CFLAGS += -O2 -Wall -g -D_GNU_SOURCE -I$(OUTPUT)include



ALL_TARGETS := lsgpio gpio-hammer gpio-event-mon

ALL_TARGETS := lsgpio gpio-hammer gpio-event-mon gpio-watch

ALL_PROGRAMS := $(patsubst %,$(OUTPUT)%,$(ALL_TARGETS))



all: $(ALL_PROGRAMS)
@@ -66,6 +66,15 @@ $(GPIO_EVENT_MON_IN): prepare FORCE $(OUTPUT)gpio-utils-in.o 
$(OUTPUT)gpio-event-mon: $(GPIO_EVENT_MON_IN)

	$(QUIET_LINK)$(CC) $(CFLAGS) $(LDFLAGS) $< -o $@



#

# gpio-watch

#

GPIO_WATCH_IN := $(OUTPUT)gpio-watch-in.o

$(GPIO_WATCH_IN): prepare FORCE

	$(Q)$(MAKE) $(build)=gpio-watch

$(OUTPUT)gpio-watch: $(GPIO_WATCH_IN)

	$(QUIET_LINK)$(CC) $(CFLAGS) $(LDFLAGS) $< -o $@



clean:

	rm -f $(ALL_PROGRAMS)

	rm -f $(OUTPUT)include/linux/gpio.h

tools/gpio/gpio-watch.c

0 → 100644
+99 −0
Original line number Diff line number Diff line 
// SPDX-License-Identifier: GPL-2.0-only

/*

 * gpio-watch - monitor unrequested lines for property changes using the

 *              character device

 *

 * Copyright (C) 2019 BayLibre SAS

 * Author: Bartosz Golaszewski <bgolaszewski@baylibre.com>

 */



#include <ctype.h>

#include <errno.h>

#include <fcntl.h>

#include <linux/gpio.h>

#include <poll.h>

#include <stdbool.h>

#include <stdio.h>

#include <stdlib.h>

#include <string.h>

#include <sys/ioctl.h>

#include <unistd.h>



int main(int argc, char **argv)

{

	struct gpioline_info_changed chg;

	struct gpioline_info req;

	struct pollfd pfd;

	int fd, i, j, ret;

	char *event, *end;

	ssize_t rd;



	if (argc < 3)

		goto err_usage;



	fd = open(argv[1], O_RDWR | O_CLOEXEC);

	if (fd < 0) {

		perror("unable to open gpiochip");

		return EXIT_FAILURE;

	}



	for (i = 0, j = 2; i < argc - 2; i++, j++) {

		memset(&req, 0, sizeof(req));



		req.line_offset = strtoul(argv[j], &end, 0);

		if (*end != '\0')

			goto err_usage;



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

		if (ret) {

			perror("unable to set up line watch");

			return EXIT_FAILURE;

		}

	}



	pfd.fd = fd;

	pfd.events = POLLIN | POLLPRI;



	for (;;) {

		ret = poll(&pfd, 1, 5000);

		if (ret < 0) {

			perror("error polling the linechanged fd");

			return EXIT_FAILURE;

		} else if (ret > 0) {

			memset(&chg, 0, sizeof(chg));

			rd = read(pfd.fd, &chg, sizeof(chg));

			if (rd < 0 || rd != sizeof(chg)) {

				if (rd != sizeof(chg))

					errno = EIO;



				perror("error reading line change event");

				return EXIT_FAILURE;

			}



			switch (chg.event_type) {

			case GPIOLINE_CHANGED_REQUESTED:

				event = "requested";

				break;

			case GPIOLINE_CHANGED_RELEASED:

				event = "released";

				break;

			case GPIOLINE_CHANGED_CONFIG:

				event = "config changed";

				break;

			default:

				fprintf(stderr,

					"invalid event type received from the kernel\n");

				return EXIT_FAILURE;

			}



			printf("line %u: %s at %llu\n",

			       chg.info.line_offset, event, chg.timestamp);

		}

	}



	return 0;



err_usage:

	printf("%s: <gpiochip> <line0> <line1> ...\n", argv[0]);

	return EXIT_FAILURE;

}