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// SPDX-License-Identifier: GPL-2.0-or-later
// SPDX-FileCopyrightText: 2023 Kent Gibson <warthog618@gmail.com>
/* Minimal example of watching for info changes on particular lines. */
#include <errno.h>
#include <gpiod.h>
#include <inttypes.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#define NUM_LINES 3
static const char *event_type(struct gpiod_info_event *event)
{
switch (gpiod_info_event_get_event_type(event)) {
case GPIOD_INFO_EVENT_LINE_REQUESTED:
return "Requested";
case GPIOD_INFO_EVENT_LINE_RELEASED:
return "Released";
case GPIOD_INFO_EVENT_LINE_CONFIG_CHANGED:
return "Reconfig";
default:
return "Unknown";
}
}
int main(void)
{
/* Example configuration - customize to suit your situation. */
static const char *const chip_path = "/dev/gpiochip0";
static const unsigned int line_offsets[NUM_LINES] = { 5, 3, 7 };
struct gpiod_info_event *event;
struct gpiod_line_info *info;
struct gpiod_chip *chip;
uint64_t timestamp_ns;
unsigned int i;
chip = gpiod_chip_open(chip_path);
if (!chip) {
fprintf(stderr, "failed to open chip: %s\n", strerror(errno));
return EXIT_FAILURE;
}
for (i = 0; i < NUM_LINES; i++) {
info = gpiod_chip_watch_line_info(chip, line_offsets[i]);
if (!info) {
fprintf(stderr, "failed to read info: %s\n",
strerror(errno));
return EXIT_FAILURE;
}
}
for (;;) {
/* Blocks until an event is available. */
event = gpiod_chip_read_info_event(chip);
if (!event) {
fprintf(stderr, "failed to read event: %s\n",
strerror(errno));
return EXIT_FAILURE;
}
info = gpiod_info_event_get_line_info(event);
timestamp_ns = gpiod_info_event_get_timestamp_ns(event);
printf("line %3d: %-9s %" PRIu64 ".%" PRIu64 "\n",
gpiod_line_info_get_offset(info), event_type(event),
timestamp_ns / 1000000000, timestamp_ns % 1000000000);
gpiod_info_event_free(event);
}
}
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