zephyr: Re-implement the Zephyr console in non-blocking mode.

The standard Zephyr console implementation doesn't make use of
`tty_set_rx_timeout()` and therefore all the functions to receive
characters block indefinitely until data is received (including
`console_read()`).

This commit also releases the GIL where it applies, e.g. the REPL and the
time sleep functions.

Signed-off-by: danicampora <danicampora@gmail.com>

ports/zephyr/mphalport.c

@@ -51,12 +51,15 @@ void mp_hal_wait_sem(struct k_sem *sem, uint32_t timeout_ms) {
         k_poll_event_init(&wait_events[1], K_POLL_TYPE_SEM_AVAILABLE, K_POLL_MODE_NOTIFY_ONLY, sem);
     }
     for (;;) {
+        mp_handle_pending(true);
+        MP_THREAD_GIL_EXIT();
         k_timeout_t wait;
         if (timeout_ms == (uint32_t)-1) {
             wait = K_FOREVER;
         } else {
             uint32_t dt = mp_hal_ticks_ms() - t0;
             if (dt >= timeout_ms) {
+                MP_THREAD_GIL_ENTER();
                 return;
             }
             wait = K_MSEC(timeout_ms - dt);
@@ -65,9 +68,9 @@ void mp_hal_wait_sem(struct k_sem *sem, uint32_t timeout_ms) {
         if (wait_events[0].state == K_POLL_STATE_SIGNALED) {
             wait_events[0].signal->signaled = 0;
             wait_events[0].state = K_POLL_STATE_NOT_READY;
-            mp_handle_pending(true);
         } else if (sem && wait_events[1].state == K_POLL_STATE_SEM_AVAILABLE) {
             wait_events[1].state = K_POLL_STATE_NOT_READY;
+            MP_THREAD_GIL_ENTER();
             return;
         }
     }

ports/zephyr/mpthreadport.c

@@ -269,6 +269,7 @@ int mp_thread_mutex_lock(mp_thread_mutex_t *mutex, int wait) {
 
 void mp_thread_mutex_unlock(mp_thread_mutex_t *mutex) {
     k_sem_give(&mutex->handle);
+    k_yield();
 }
 
 void mp_thread_deinit(void) {

ports/zephyr/src/zephyr_getchar.c

@@ -50,14 +50,16 @@ static int console_irq_input_hook(uint8_t ch) {
     return 1;
 }
 
-uint8_t zephyr_getchar(void) {
-    mp_hal_wait_sem(&uart_sem, -1);
-    k_sem_take(&uart_sem, K_FOREVER);
-    unsigned int key = irq_lock();
-    uint8_t c = uart_ringbuf[i_get++];
-    i_get &= UART_BUFSIZE - 1;
-    irq_unlock(key);
-    return c;
+int zephyr_getchar(void) {
+    mp_hal_wait_sem(&uart_sem, 0);
+    if (k_sem_take(&uart_sem, K_MSEC(0)) == 0) {
+        unsigned int key = irq_lock();
+        int c = (int)uart_ringbuf[i_get++];
+        i_get &= UART_BUFSIZE - 1;
+        irq_unlock(key);
+        return c;
+    }
+    return -1;
 }
 
 void zephyr_getchar_init(void) {

ports/zephyr/src/zephyr_getchar.h

@@ -17,4 +17,4 @@
 #include <stdint.h>
 
 void zephyr_getchar_init(void);
-uint8_t zephyr_getchar(void);
+int zephyr_getchar(void);

ports/zephyr/src/zephyr_start.c

@@ -24,14 +24,14 @@
  * THE SOFTWARE.
  */
 #include <zephyr/zephyr.h>
-#include <zephyr/console/console.h>
 #include "zephyr_getchar.h"
 
 int real_main(void);
+int mp_console_init(void);
 
 void main(void) {
     #ifdef CONFIG_CONSOLE_SUBSYS
-    console_init();
+    mp_console_init();
     #else
     zephyr_getchar_init();
     #endif

ports/zephyr/uart_core.c

@@ -25,10 +25,28 @@
  */
 #include <unistd.h>
 #include "py/mpconfig.h"
+#include "py/runtime.h"
 #include "src/zephyr_getchar.h"
 // Zephyr headers
-#include <zephyr/drivers/uart.h>
+#include <zephyr/zephyr.h>
+#include <zephyr/device.h>
 #include <zephyr/console/console.h>
+#include <zephyr/console/tty.h>
+#include <zephyr/drivers/uart.h>
+
+
+#ifdef CONFIG_CONSOLE_SUBSYS
+
+static int mp_console_putchar(char c);
+static int mp_console_getchar(void);
+
+
+static struct tty_serial mp_console_serial;
+
+static uint8_t mp_console_rxbuf[CONFIG_CONSOLE_GETCHAR_BUFSIZE];
+static uint8_t mp_console_txbuf[CONFIG_CONSOLE_PUTCHAR_BUFSIZE];
+
+#endif  // CONFIG_CONSOLE_SUBSYS
 
 /*
  * Core UART functions to implement for a port
@@ -36,11 +54,18 @@
 
 // Receive single character
 int mp_hal_stdin_rx_chr(void) {
-    #ifdef CONFIG_CONSOLE_SUBSYS
-    return console_getchar();
-    #else
-    return zephyr_getchar();
-    #endif
+    for (;;) {
+        int _chr;
+        #ifdef CONFIG_CONSOLE_SUBSYS
+        _chr = mp_console_getchar();
+        #else
+        _chr = zephyr_getchar();
+        #endif
+        if (_chr >= 0) {
+            return _chr;
+        }
+        MICROPY_EVENT_POLL_HOOK
+    }
 }
 
 // Send string of given length
@@ -49,8 +74,8 @@ mp_uint_t mp_hal_stdout_tx_strn(const char *str, mp_uint_t len) {
     #ifdef CONFIG_CONSOLE_SUBSYS
     while (len--) {
         char c = *str++;
-        while (console_putchar(c) == -1) {
-            k_msleep(1);
+        while (mp_console_putchar(c) == -1) {
+            MICROPY_EVENT_POLL_HOOK
         }
     }
     #else
@@ -63,3 +88,58 @@ mp_uint_t mp_hal_stdout_tx_strn(const char *str, mp_uint_t len) {
     #endif
     return ret;
 }
+
+
+#ifdef CONFIG_CONSOLE_SUBSYS
+
+int mp_console_init(void) {
+
+    const struct device *uart_dev;
+    int ret;
+
+    uart_dev = DEVICE_DT_GET(DT_CHOSEN(zephyr_console));
+    if (!device_is_ready(uart_dev)) {
+        return -ENODEV;
+    }
+
+    ret = tty_init(&mp_console_serial, uart_dev);
+
+    if (ret) {
+        return ret;
+    }
+
+    /* Checks device driver supports for interrupt driven data transfers. */
+    if (CONFIG_CONSOLE_GETCHAR_BUFSIZE + CONFIG_CONSOLE_PUTCHAR_BUFSIZE) {
+        const struct uart_driver_api *api =
+            (const struct uart_driver_api *)uart_dev->api;
+        if (!api->irq_callback_set) {
+            return -ENOTSUP;
+        }
+    }
+
+    tty_set_tx_buf(&mp_console_serial, mp_console_txbuf, sizeof(mp_console_txbuf));
+    tty_set_rx_buf(&mp_console_serial, mp_console_rxbuf, sizeof(mp_console_rxbuf));
+
+    tty_set_rx_timeout(&mp_console_serial, 0);
+    tty_set_tx_timeout(&mp_console_serial, 1);
+
+    return 0;
+}
+
+static int mp_console_putchar(char c) {
+    return tty_write(&mp_console_serial, &c, 1);
+}
+
+static int mp_console_getchar(void) {
+    uint8_t c;
+    int res;
+
+    res = tty_read(&mp_console_serial, &c, 1);
+    if (res < 0) {
+        return res;
+    }
+
+    return c;
+}
+
+#endif  // CONFIG_CONSOLE_SUBSYS