// 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 <inttypes.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 gpio_v2_line_info_changed chg; struct gpio_v2_line_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.offset = strtoul(argv[j], &end, 0); if (*end != '\0') goto err_usage; ret = ioctl(fd, GPIO_V2_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 GPIO_V2_LINE_CHANGED_REQUESTED: event = "requested"; break; case GPIO_V2_LINE_CHANGED_RELEASED: event = "released"; break; case GPIO_V2_LINE_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 %" PRIu64 "\n", chg.info.offset, event, (uint64_t)chg.timestamp_ns); } } return 0; err_usage: printf("%s: <gpiochip> <line0> <line1> ...\n", argv[0]); return EXIT_FAILURE; }