mimxrt/machine_uart: Add uart.deinit method and machine_uart_deinit_all.

The call to machine_uart_deinit_all() is needed to avoid a crash after soft
reset, if a UART had been used and data arrives before it is instantiated
again.

Signed-off-by: robert-hh <robert@hammelrath.com>

ports/mimxrt/machine_uart.c

@@ -288,6 +288,14 @@ STATIC mp_obj_t machine_uart_init(size_t n_args, const mp_obj_t *args, mp_map_t
 }
 MP_DEFINE_CONST_FUN_OBJ_KW(machine_uart_init_obj, 1, machine_uart_init);
 
+// uart.deinit()
+STATIC mp_obj_t machine_uart_deinit(mp_obj_t self_in) {
+    machine_uart_obj_t *self = MP_OBJ_TO_PTR(self_in);
+    LPUART_Deinit(self->lpuart);
+    return mp_const_none;
+}
+STATIC MP_DEFINE_CONST_FUN_OBJ_1(machine_uart_deinit_obj, machine_uart_deinit);
+
 STATIC mp_obj_t machine_uart_any(mp_obj_t self_in) {
     machine_uart_obj_t *self = MP_OBJ_TO_PTR(self_in);
     size_t count = LPUART_TransferGetRxRingBufferLength(self->lpuart, &self->handle);
@@ -314,8 +322,18 @@ STATIC mp_obj_t machine_uart_txdone(mp_obj_t self_in) {
 }
 STATIC MP_DEFINE_CONST_FUN_OBJ_1(machine_uart_txdone_obj, machine_uart_txdone);
 
+// Deinitialize all defined UARTs
+void machine_uart_deinit_all(void) {
+    for (int i = 0; i < sizeof(uart_index_table); i++) {
+        if (uart_index_table[i] != 0) {
+            LPUART_Deinit(uart_base_ptr_table[uart_index_table[i]]);
+        }
+    }
+}
+
 STATIC const mp_rom_map_elem_t machine_uart_locals_dict_table[] = {
     { MP_ROM_QSTR(MP_QSTR_init), MP_ROM_PTR(&machine_uart_init_obj) },
+    { MP_ROM_QSTR(MP_QSTR_deinit), MP_ROM_PTR(&machine_uart_deinit_obj) },
 
     { MP_ROM_QSTR(MP_QSTR_any), MP_ROM_PTR(&machine_uart_any_obj) },
 

ports/mimxrt/main.c

@@ -124,6 +124,7 @@ int main(void) {
         #if MICROPY_PY_NETWORK
         mod_network_deinit();
         #endif
+        machine_uart_deinit_all();
         machine_pwm_deinit_all();
         soft_timer_deinit();
         gc_sweep_all();

ports/mimxrt/modmachine.h

@@ -43,6 +43,7 @@ extern const mp_obj_type_t machine_wdt_type;
 void machine_adc_init(void);
 void machine_pin_irq_deinit(void);
 void machine_pwm_deinit_all(void);
+void machine_uart_deinit_all(void);
 void machine_timer_init_PIT(void);
 void machine_sdcard_init0(void);
 void mimxrt_sdram_init(void);