1 // SPDX-License-Identifier: GPL-2.0-only
3 * gpio-event-mon - monitor GPIO line events from userspace
5 * Copyright (C) 2016 Linus Walleij
8 * gpio-event-mon -n <device-name> -o <offset>
23 #include <sys/ioctl.h>
24 #include <sys/types.h>
25 #include <linux/gpio.h>
26 #include "gpio-utils.h"
28 int monitor_device(const char *device_name,
30 unsigned int num_lines,
31 struct gpio_v2_line_config *config,
34 struct gpio_v2_line_values values;
40 ret = asprintf(&chrdev_name, "/dev/%s", device_name);
44 cfd = open(chrdev_name, 0);
47 fprintf(stderr, "Failed to open %s\n", chrdev_name);
51 ret = gpiotools_request_line(device_name, lines, num_lines, config,
54 goto exit_device_close;
58 /* Read initial states */
61 for (i = 0; i < num_lines; i++)
62 gpiotools_set_bit(&values.mask, i);
63 ret = gpiotools_get_values(lfd, &values);
66 "Failed to issue GPIO LINE GET VALUES IOCTL (%d)\n",
72 fprintf(stdout, "Monitoring line %d on %s\n", lines[0], device_name);
73 fprintf(stdout, "Initial line value: %d\n",
74 gpiotools_test_bit(values.bits, 0));
76 fprintf(stdout, "Monitoring lines %d", lines[0]);
77 for (i = 1; i < num_lines - 1; i++)
78 fprintf(stdout, ", %d", lines[i]);
79 fprintf(stdout, " and %d on %s\n", lines[i], device_name);
80 fprintf(stdout, "Initial line values: %d",
81 gpiotools_test_bit(values.bits, 0));
82 for (i = 1; i < num_lines - 1; i++)
83 fprintf(stdout, ", %d",
84 gpiotools_test_bit(values.bits, i));
85 fprintf(stdout, " and %d\n",
86 gpiotools_test_bit(values.bits, i));
90 struct gpio_v2_line_event event;
92 ret = read(lfd, &event, sizeof(event));
94 if (errno == -EAGAIN) {
95 fprintf(stderr, "nothing available\n");
99 fprintf(stderr, "Failed to read event (%d)\n",
105 if (ret != sizeof(event)) {
106 fprintf(stderr, "Reading event failed\n");
110 fprintf(stdout, "GPIO EVENT at %llu on line %d (%d|%d) ",
111 event.timestamp_ns, event.offset, event.line_seqno,
114 case GPIO_V2_LINE_EVENT_RISING_EDGE:
115 fprintf(stdout, "rising edge");
117 case GPIO_V2_LINE_EVENT_FALLING_EDGE:
118 fprintf(stdout, "falling edge");
121 fprintf(stdout, "unknown event");
123 fprintf(stdout, "\n");
131 if (close(lfd) == -1)
132 perror("Failed to close line file");
134 if (close(cfd) == -1)
135 perror("Failed to close GPIO character device file");
141 void print_usage(void)
143 fprintf(stderr, "Usage: gpio-event-mon [options]...\n"
144 "Listen to events on GPIO lines, 0->1 1->0\n"
145 " -n <name> Listen on GPIOs on a named device (must be stated)\n"
146 " -o <n> Offset of line to monitor (may be repeated)\n"
147 " -d Set line as open drain\n"
148 " -s Set line as open source\n"
149 " -r Listen for rising edges\n"
150 " -f Listen for falling edges\n"
151 " [-c <n>] Do <n> loops (optional, infinite loop if not stated)\n"
152 " -? This helptext\n"
155 "gpio-event-mon -n gpiochip0 -o 4 -r -f\n"
160 (GPIO_V2_LINE_FLAG_EDGE_RISING | \
161 GPIO_V2_LINE_FLAG_EDGE_FALLING)
163 int main(int argc, char **argv)
165 const char *device_name = NULL;
166 unsigned int lines[GPIO_V2_LINES_MAX];
167 unsigned int num_lines = 0;
168 unsigned int loops = 0;
169 struct gpio_v2_line_config config;
172 memset(&config, 0, sizeof(config));
173 config.flags = GPIO_V2_LINE_FLAG_INPUT;
174 while ((c = getopt(argc, argv, "c:n:o:dsrf?")) != -1) {
177 loops = strtoul(optarg, NULL, 10);
180 device_name = optarg;
183 if (num_lines >= GPIO_V2_LINES_MAX) {
187 lines[num_lines] = strtoul(optarg, NULL, 10);
191 config.flags |= GPIO_V2_LINE_FLAG_OPEN_DRAIN;
194 config.flags |= GPIO_V2_LINE_FLAG_OPEN_SOURCE;
197 config.flags |= GPIO_V2_LINE_FLAG_EDGE_RISING;
200 config.flags |= GPIO_V2_LINE_FLAG_EDGE_FALLING;
208 if (!device_name || num_lines == 0) {
212 if (!(config.flags & EDGE_FLAGS)) {
213 printf("No flags specified, listening on both rising and "
215 config.flags |= EDGE_FLAGS;
217 return monitor_device(device_name, lines, num_lines, &config, loops);