/* * gpio-event-mon - monitor GPIO line events from userspace * * 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); }