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// 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;
}
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