Playing around with interrupt driver uarts in Zephyr

main.c

#include <string.h>
#include <zephyr.h>

#include <console/console.h>
#include <drivers/uart.h>

/* size of stack area used by each thread */
#define STACKSIZE 1024
#define UART_1 "UART_1"
#define TTY_BUF_SZ 512

struct tty {
  struct k_sem rx_sem;
  size_t rx_put;
  size_t rx_get;
  size_t rx_buf_sz;
  uint8_t rx_buf[TTY_BUF_SZ];
};

struct tty uart1_tty = {.rx_buf_sz = TTY_BUF_SZ};

static void tty_uart_isr(const struct device *dev, void *user_data) {
  struct tty *tty = user_data;

  uart_irq_update(dev);

  if (uart_irq_rx_ready(dev)) {
    uint8_t c;
    while (1) {
      int read = uart_fifo_read(dev, &c, 1);
      if (read == 0) {
        break;
      }
      tty->rx_buf[tty->rx_put++] = c;
      if (tty->rx_put >= tty->rx_buf_sz) {
        tty->rx_put = 0;
      }
      k_sem_give(&tty->rx_sem);
    }
  }
}

static int tty_read_line(struct tty *tty, unsigned char *buf, size_t size) {
  int bytes = 0;
  for (int i = 0; i < size; i++) {
    int res = k_sem_take(&tty->rx_sem, K_FOREVER);
    if (res < 0) {
      return res;
    }
    buf[i] = tty->rx_buf[tty->rx_get++];
    bytes++;
    if (tty->rx_get >= tty->rx_buf_sz) {
      tty->rx_get = 0;
    }
    if (buf[i] == '\n') {
      break;
    }
  }
  return bytes;
}

void main() {
  const struct device *uart1 = device_get_binding(UART_1);
  console_getline_init();

  k_sem_init(&uart1_tty.rx_sem, 0, K_SEM_MAX_LIMIT);
  uart_irq_callback_user_data_set(uart1, tty_uart_isr, &uart1_tty);
  uart_irq_rx_enable(uart1);

  char rline[256];

  char *reset = "AT+RST\r\n";
  for (int i = 0; i < strlen(reset); i++) {
    uart_poll_out(uart1, reset[i]);
  }

  while (true) {
    int size = tty_read_line(&uart1_tty, rline, 256);
    if (size) {
      rline[size] = '\0';
      printk("%s", rline);
      if (strcmp(rline, "ready\r\n") == 0) {
        break;
      }
    } else {
      k_yield();
    }
  }

  char *echo_off = "ATE0\r\n";
  for (int i = 0; i < strlen(echo_off); i++) {
    uart_poll_out(uart1, echo_off[i]);
  }

  while (true) {
    int size = tty_read_line(&uart1_tty, rline, 256);
    if (size) {
      rline[size] = '\0';
      printk("%s", rline);
      if (strcmp(rline, "OK\r\n") == 0) {
        break;
      }
    } else {
      k_yield();
    }
  }

  printk("\n");

  while (true) {
    printk("$ ");
    char *line = console_getline();
    for (int i = 0; i < strlen(line); i++) {
      uart_poll_out(uart1, line[i]);
    }
    uart_poll_out(uart1, '\r');
    uart_poll_out(uart1, '\n');

    while (true) {
      int size = tty_read_line(&uart1_tty, rline, 256);
      if (size) {
        rline[size] = '\0';
        printk("%s", rline);
        if (strcmp(rline, "OK\r\n") == 0 || strcmp(rline, "ERROR\r\n") == 0) {
          break;
        }
      } else {
        k_yield();
      }
    }
  }
}