zephyr: Fix problem with flush at low baudrates.

Also make the read() method interrupt safe.

Signed-off-by: Daniel Campora <[email protected]>

Author: danicampora

ports/zephyr/machine_uart.c

@@ -31,6 +31,7 @@
 
 #include <zephyr/kernel.h>
 #include <zephyr/drivers/uart.h>
+#include <zephyr/irq.h>
 
 #include "py/mperrno.h"
 #include "py/obj.h"
@@ -62,6 +63,7 @@ typedef struct _machine_uart_obj_t {
     uint16_t timeout_char;  // timeout waiting between chars (in ms)
     ringbuf_t rx_ringbuffer;
     ringbuf_t tx_ringbuffer;
+    bool tx_complete;
 } machine_uart_obj_t;
 
 static const char *_parity_name[] = {"None", "Odd", "Even", "Mark", "Space"};
@@ -168,6 +170,7 @@ static mp_obj_t mp_machine_uart_make_new(const mp_obj_type_t *type, size_t n_arg
 
     machine_uart_obj_t *self = mp_obj_malloc_with_finaliser(machine_uart_obj_t, &machine_uart_type);
     self->dev = zephyr_device_find(args[0]);
+    self->tx_complete = true;
 
     mp_map_t kw_args;
     mp_map_init_fixed_table(&kw_args, n_kw, args + n_args);
@@ -186,7 +189,7 @@ static mp_int_t mp_machine_uart_any(machine_uart_obj_t *self) {
 }
 
 static bool mp_machine_uart_txdone(machine_uart_obj_t *self) {
-    return ringbuf_avail(&self->tx_ringbuffer) ? false : true;
+    return (ringbuf_avail(&self->tx_ringbuffer) || (self->tx_complete == false)) ? false : true;
 }
 
 static mp_uint_t mp_machine_uart_read(mp_obj_t self_in, void *buf_in, mp_uint_t size, int *errcode) {
@@ -199,7 +202,9 @@ static mp_uint_t mp_machine_uart_read(mp_obj_t self_in, void *buf_in, mp_uint_t
     do {
         int _rx_len = MIN(ringbuf_avail(&self->rx_ringbuffer), size - bytes_read);
         if (_rx_len > 0) {
+            uint32_t key = irq_lock();
             ringbuf_get_bytes(&self->rx_ringbuffer, &buffer[bytes_read], _rx_len);
+            irq_unlock(key);
             bytes_read += _rx_len;
             elapsed_ms = 0;
             time_to_wait = self->timeout_char;
@@ -233,6 +238,7 @@ static mp_uint_t mp_machine_uart_write(mp_obj_t self_in, const void *buf_in, mp_
     }
 
     ringbuf_put_bytes(&self->tx_ringbuffer, &buffer[_ex_size], size - _ex_size);
+    self->tx_complete = false;
     uart_irq_tx_enable(self->dev);
 
     return size;
@@ -291,8 +297,9 @@ static void uart_interrupt_handler(const struct device *dev, void *user_data) {
                 _buffer_tx_len = MIN(_max_uart_tx_len, _buffer_tx_len);
                 ringbuf_get_bytes(&self->tx_ringbuffer, _tx_buffer, _buffer_tx_len);
                 uart_fifo_fill(dev, _tx_buffer, _buffer_tx_len);
-            } else {
+            } else if (uart_irq_tx_complete(dev)) {
                 uart_irq_tx_disable(dev);
+                self->tx_complete = true;
             }
         }
     }