Clean UART on reset

Author: kamtom480

ports/cxd56/common-hal/busio/UART.c

@@ -187,3 +187,12 @@ bool common_hal_busio_uart_ready_to_tx(busio_uart_obj_t *self) {
     ioctl(busio_uart_dev[self->number].fd, TCFLSH, (long unsigned int)NULL);
     return true;
 }
+
+void busio_uart_reset(void) {
+    for (int i = 0; i < MP_ARRAY_SIZE(busio_uart_dev); i++) {
+        if (busio_uart_dev[i].fd >= 0) {
+            close(busio_uart_dev[i].fd);
+            busio_uart_dev[i].fd = -1;
+        }
+    }
+}

ports/cxd56/common-hal/busio/UART.h

@@ -40,4 +40,6 @@ typedef struct {
     uint32_t timeout;
 } busio_uart_obj_t;
 
+void busio_uart_reset(void);
+
 #endif // MICROPY_INCLUDED_CXD56_COMMON_HAL_BUSIO_UART_H

ports/cxd56/supervisor/port.c

@@ -35,6 +35,7 @@
 #include "common-hal/analogio/AnalogIn.h"
 #include "common-hal/pulseio/PulseOut.h"
 #include "common-hal/pulseio/PWMOut.h"
+#include "common-hal/busio/UART.h"
 
 safe_mode_t port_init(void) {
     boardctl(BOARDIOC_INIT, 0);
@@ -60,6 +61,9 @@ void reset_port(void) {
     pulseout_reset();
     pwmout_reset();
 #endif
+#if CIRCUITPY_BUSIO
+    busio_uart_reset();
+#endif
 
     reset_all_pins();
 }