GPIO chdev v2 memo

gpio_chdev_v2.c

#include <errno.h>
#include <fcntl.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/ioctl.h>
#include <sys/types.h>
#include <unistd.h>

#include <linux/gpio.h>

static void perror_exit(const char* s) {
  perror(s);
  exit(1);
}

int main() {
  int fd = open("/dev/gpiochip0", O_RDWR | O_CLOEXEC);
  if (fd < 0) {
    perror_exit("open");
  }

  printf("[+] open(\"/dev/gpiochip0\") = %d\n", fd);

  puts("");

  struct gpiochip_info info;
  if (ioctl(fd, GPIO_GET_CHIPINFO_IOCTL, &info) < 0) {
    perror_exit("GPIO_GET_CHIPINFO_IOCTL");
  }

  printf("[+] info.name = \"%s\"\n", info.name);
  printf("[+] info.label = \"%s\"\n", info.label);
  printf("[+] info.lines = \"%u\"\n", info.lines);

  puts("");

  for (unsigned int offset = 0; offset < info.lines; ++offset) {
    struct gpio_v2_line_info line = {
        .offset = offset,
    };
    if (ioctl(fd, GPIO_V2_GET_LINEINFO_IOCTL, &line) < 0) {
      perror_exit("GPIO_V2_GET_LINEINFO_IOCTL");
    }

    printf("[+] %3u: %08llx, name = \"%s\", consumer = \"%s\"\n", offset, line.flags, line.name,
           line.consumer);
  }

  puts("");

  puts("[+] gpio_v2_line_flag");
#define PRINT_FLAG(flag) printf("[+] %08llx: " #flag "\n", (long long unsigned int)flag);

  PRINT_FLAG(GPIO_V2_LINE_FLAG_USED);
  PRINT_FLAG(GPIO_V2_LINE_FLAG_ACTIVE_LOW);
  PRINT_FLAG(GPIO_V2_LINE_FLAG_INPUT);
  PRINT_FLAG(GPIO_V2_LINE_FLAG_OUTPUT);
  PRINT_FLAG(GPIO_V2_LINE_FLAG_EDGE_RISING);
  PRINT_FLAG(GPIO_V2_LINE_FLAG_EDGE_FALLING);
  PRINT_FLAG(GPIO_V2_LINE_FLAG_OPEN_DRAIN);
  PRINT_FLAG(GPIO_V2_LINE_FLAG_OPEN_SOURCE);
  PRINT_FLAG(GPIO_V2_LINE_FLAG_BIAS_PULL_UP);
  PRINT_FLAG(GPIO_V2_LINE_FLAG_BIAS_PULL_DOWN);
  PRINT_FLAG(GPIO_V2_LINE_FLAG_BIAS_DISABLED);
  PRINT_FLAG(GPIO_V2_LINE_FLAG_EVENT_CLOCK_REALTIME);

#undef PRINT_FLAG

  puts("");

  puts("[+] waiting MIO23 (SW1) rising edge event");

  {
    struct gpio_v2_line_request req;
    memset(&req, 0, sizeof req);
    req.offsets[0] = 23;
    req.num_lines = 1;
    req.config.flags = GPIO_V2_LINE_FLAG_INPUT | GPIO_V2_LINE_FLAG_EDGE_RISING;
    req.config.num_attrs = 0;
    if (ioctl(fd, GPIO_V2_GET_LINE_IOCTL, &req) < 0) {
      perror_exit("GPIO_V2_GET_LINE_IOCTL");
    }

    for (int i = 0; i < 10; ++i) {
      struct gpio_v2_line_event event;
      int ret = read(req.fd, &event, sizeof event);
      if (ret < 0) {
        perror_exit("read");
      }
      if (ret != sizeof event) {
        return 1;
      }

      printf("[+] event.id = %02x\n", event.id);
    }

    close(req.fd);
  }

  puts("");

  puts("[+] waiting MIO23 (SW1) falling edge event");

  {
    struct gpio_v2_line_request req;
    memset(&req, 0, sizeof req);
    req.offsets[0] = 23;
    req.num_lines = 1;
    req.config.flags = GPIO_V2_LINE_FLAG_INPUT | GPIO_V2_LINE_FLAG_EDGE_FALLING;
    req.config.num_attrs = 0;
    if (ioctl(fd, GPIO_V2_GET_LINE_IOCTL, &req) < 0) {
      perror_exit("GPIO_V2_GET_LINE_IOCTL");
    }

    for (int i = 0; i < 10; ++i) {
      struct gpio_v2_line_event event;
      int ret = read(req.fd, &event, sizeof event);
      if (ret < 0) {
        perror_exit("read");
      }
      if (ret != sizeof event) {
        return 1;
      }

      printf("[+] event.id = %02x\n", event.id);
    }

    close(req.fd);
  }

  puts("");

  puts("[+] waiting MIO23 (SW1) both edges event");

  {
    struct gpio_v2_line_request req;
    memset(&req, 0, sizeof req);
    req.offsets[0] = 23;
    req.num_lines = 1;
    req.config.flags =
        GPIO_V2_LINE_FLAG_INPUT | GPIO_V2_LINE_FLAG_EDGE_FALLING | GPIO_V2_LINE_FLAG_EDGE_RISING;
    req.config.num_attrs = 0;
    if (ioctl(fd, GPIO_V2_GET_LINE_IOCTL, &req) < 0) {
      perror_exit("GPIO_V2_GET_LINE_IOCTL");
    }

    for (int i = 0; i < 10; ++i) {
      struct gpio_v2_line_event event;
      int ret = read(req.fd, &event, sizeof event);
      if (ret < 0) {
        perror_exit("read");
      }
      if (ret != sizeof event) {
        return 1;
      }

      printf("[+] event.id = %02x\n", event.id);
    }

    close(req.fd);
  }

  puts("");

  puts("[+] MIO19 (LED1) blink");

  {
    struct gpio_v2_line_request req;
    memset(&req, 0, sizeof req);
    req.offsets[0] = 19;
    req.num_lines = 1;
    req.config.flags = GPIO_V2_LINE_FLAG_OUTPUT;
    req.config.num_attrs = 1;
    req.config.attrs[0].attr.id = GPIO_V2_LINE_ATTR_ID_OUTPUT_VALUES;
    req.config.attrs[0].mask = 1;
    req.config.attrs[0].attr.values = 1; // initial value = 1
    if (ioctl(fd, GPIO_V2_GET_LINE_IOCTL, &req) < 0) {
      perror_exit("GPIO_V2_GET_LINE_IOCTL");
    }

    for (int i = 0; i < 20; ++i) {
      struct gpio_v2_line_values values;

      usleep(500000); // 500 ms

      values.mask = 1;
      values.bits = 0;
      if (ioctl(req.fd, GPIO_V2_LINE_SET_VALUES_IOCTL, &values) < 0) {
        perror_exit("GPIO_V2_LINE_SET_VALUES_IOCTL");
      }

      if (ioctl(req.fd, GPIO_V2_LINE_GET_VALUES_IOCTL, &values) < 0) {
        perror_exit("GPIO_V2_LINE_GET_VALUES_IOCTL");
      }
      printf("[+] values.bits = %08x\n", values.bits);

      usleep(500000); // 500 ms

      values.mask = 1;
      values.bits = 1;
      if (ioctl(req.fd, GPIO_V2_LINE_SET_VALUES_IOCTL, &values) < 0) {
        perror_exit("GPIO_V2_LINE_SET_VALUES_IOCTL");
      }

      if (ioctl(req.fd, GPIO_V2_LINE_GET_VALUES_IOCTL, &values) < 0) {
        perror_exit("GPIO_V2_LINE_GET_VALUES_IOCTL");
      }
      printf("[+] values.bits = %08x\n", values.bits);
    }

    close(req.fd);
  }

  close(fd);
}