1 // SPDX-License-Identifier: GPL-2.0-only 2 /* 3 * gpio-event-mon - monitor GPIO line events from userspace 4 * 5 * Copyright (C) 2016 Linus Walleij 6 * 7 * Usage: 8 * gpio-event-mon -n <device-name> -o <offset> 9 */ 10 11 #include <unistd.h> 12 #include <stdlib.h> 13 #include <stdbool.h> 14 #include <stdint.h> 15 #include <stdio.h> 16 #include <dirent.h> 17 #include <errno.h> 18 #include <string.h> 19 #include <poll.h> 20 #include <fcntl.h> 21 #include <getopt.h> 22 #include <inttypes.h> 23 #include <sys/ioctl.h> 24 #include <sys/types.h> 25 #include <linux/gpio.h> 26 27 int monitor_device(const char *device_name, 28 unsigned int line, 29 uint32_t handleflags, 30 uint32_t eventflags, 31 unsigned int loops) 32 { 33 struct gpioevent_request req; 34 struct gpiohandle_data data; 35 char *chrdev_name; 36 int fd; 37 int ret; 38 int i = 0; 39 40 ret = asprintf(&chrdev_name, "/dev/%s", device_name); 41 if (ret < 0) 42 return -ENOMEM; 43 44 fd = open(chrdev_name, 0); 45 if (fd == -1) { 46 ret = -errno; 47 fprintf(stderr, "Failed to open %s\n", chrdev_name); 48 goto exit_free_name; 49 } 50 51 req.lineoffset = line; 52 req.handleflags = handleflags; 53 req.eventflags = eventflags; 54 strcpy(req.consumer_label, "gpio-event-mon"); 55 56 ret = ioctl(fd, GPIO_GET_LINEEVENT_IOCTL, &req); 57 if (ret == -1) { 58 ret = -errno; 59 fprintf(stderr, "Failed to issue GET EVENT " 60 "IOCTL (%d)\n", 61 ret); 62 goto exit_close_error; 63 } 64 65 /* Read initial states */ 66 ret = ioctl(req.fd, GPIOHANDLE_GET_LINE_VALUES_IOCTL, &data); 67 if (ret == -1) { 68 ret = -errno; 69 fprintf(stderr, "Failed to issue GPIOHANDLE GET LINE " 70 "VALUES IOCTL (%d)\n", 71 ret); 72 goto exit_close_error; 73 } 74 75 fprintf(stdout, "Monitoring line %d on %s\n", line, device_name); 76 fprintf(stdout, "Initial line value: %d\n", data.values[0]); 77 78 while (1) { 79 struct gpioevent_data event; 80 81 ret = read(req.fd, &event, sizeof(event)); 82 if (ret == -1) { 83 if (errno == -EAGAIN) { 84 fprintf(stderr, "nothing available\n"); 85 continue; 86 } else { 87 ret = -errno; 88 fprintf(stderr, "Failed to read event (%d)\n", 89 ret); 90 break; 91 } 92 } 93 94 if (ret != sizeof(event)) { 95 fprintf(stderr, "Reading event failed\n"); 96 ret = -EIO; 97 break; 98 } 99 fprintf(stdout, "GPIO EVENT %llu: ", event.timestamp); 100 switch (event.id) { 101 case GPIOEVENT_EVENT_RISING_EDGE: 102 fprintf(stdout, "rising edge"); 103 break; 104 case GPIOEVENT_EVENT_FALLING_EDGE: 105 fprintf(stdout, "falling edge"); 106 break; 107 default: 108 fprintf(stdout, "unknown event"); 109 } 110 fprintf(stdout, "\n"); 111 112 i++; 113 if (i == loops) 114 break; 115 } 116 117 exit_close_error: 118 if (close(fd) == -1) 119 perror("Failed to close GPIO character device file"); 120 exit_free_name: 121 free(chrdev_name); 122 return ret; 123 } 124 125 void print_usage(void) 126 { 127 fprintf(stderr, "Usage: gpio-event-mon [options]...\n" 128 "Listen to events on GPIO lines, 0->1 1->0\n" 129 " -n <name> Listen on GPIOs on a named device (must be stated)\n" 130 " -o <n> Offset to monitor\n" 131 " -d Set line as open drain\n" 132 " -s Set line as open source\n" 133 " -r Listen for rising edges\n" 134 " -f Listen for falling edges\n" 135 " [-c <n>] Do <n> loops (optional, infinite loop if not stated)\n" 136 " -? This helptext\n" 137 "\n" 138 "Example:\n" 139 "gpio-event-mon -n gpiochip0 -o 4 -r -f\n" 140 ); 141 } 142 143 int main(int argc, char **argv) 144 { 145 const char *device_name = NULL; 146 unsigned int line = -1; 147 unsigned int loops = 0; 148 uint32_t handleflags = GPIOHANDLE_REQUEST_INPUT; 149 uint32_t eventflags = 0; 150 int c; 151 152 while ((c = getopt(argc, argv, "c:n:o:dsrf?")) != -1) { 153 switch (c) { 154 case 'c': 155 loops = strtoul(optarg, NULL, 10); 156 break; 157 case 'n': 158 device_name = optarg; 159 break; 160 case 'o': 161 line = strtoul(optarg, NULL, 10); 162 break; 163 case 'd': 164 handleflags |= GPIOHANDLE_REQUEST_OPEN_DRAIN; 165 break; 166 case 's': 167 handleflags |= GPIOHANDLE_REQUEST_OPEN_SOURCE; 168 break; 169 case 'r': 170 eventflags |= GPIOEVENT_REQUEST_RISING_EDGE; 171 break; 172 case 'f': 173 eventflags |= GPIOEVENT_REQUEST_FALLING_EDGE; 174 break; 175 case '?': 176 print_usage(); 177 return -1; 178 } 179 } 180 181 if (!device_name || line == -1) { 182 print_usage(); 183 return -1; 184 } 185 if (!eventflags) { 186 printf("No flags specified, listening on both rising and " 187 "falling edges\n"); 188 eventflags = GPIOEVENT_REQUEST_BOTH_EDGES; 189 } 190 return monitor_device(device_name, line, handleflags, 191 eventflags, loops); 192 } 193