stmhal: Add support for UART5

I tested this on my CERB40 board and it seems to be working fine.

stmhal/boards/CERB40/mpconfigboard.h

@@ -38,6 +38,10 @@
 #define MICROPY_HW_UART3_CTS  (GPIO_PIN_11)
 #define MICROPY_HW_UART4_PORT (GPIOA)
 #define MICROPY_HW_UART4_PINS (GPIO_PIN_0 | GPIO_PIN_1)
+#define MICROPY_HW_UART5_TX_PORT (GPIOC)
+#define MICROPY_HW_UART5_TX_PIN  (GPIO_PIN_12)
+#define MICROPY_HW_UART5_RX_PORT (GPIOD)
+#define MICROPY_HW_UART5_RX_PIN  (GPIO_PIN_2)
 #define MICROPY_HW_UART6_PORT (GPIOC)
 #define MICROPY_HW_UART6_PINS (GPIO_PIN_6 | GPIO_PIN_7)
 

stmhal/stm32f4xx_it.c

@@ -413,6 +413,10 @@ void UART4_IRQHandler(void) {
     uart_irq_handler(4);
 }
 
+void UART5_IRQHandler(void) {
+    uart_irq_handler(5);
+}
+
 void USART6_IRQHandler(void) {
     uart_irq_handler(6);
 }

stmhal/uart.c

@@ -185,6 +185,31 @@ STATIC bool uart_init2(pyb_uart_obj_t *uart_obj) {
             break;
         #endif
 
+        #if defined(UART5) && \
+            defined(MICROPY_HW_UART5_TX_PORT) && \
+            defined(MICROPY_HW_UART5_TX_PIN) && \
+            defined(MICROPY_HW_UART5_RX_PORT) && \
+            defined(MICROPY_HW_UART5_RX_PIN)
+        case PYB_UART_5:
+            UARTx = UART5;
+            irqn = UART5_IRQn;
+            GPIO_AF_UARTx = GPIO_AF8_UART5;
+            GPIO_Port = MICROPY_HW_UART5_TX_PORT;
+            GPIO_Pin = MICROPY_HW_UART5_TX_PIN;
+            __UART5_CLK_ENABLE();
+
+            // The code after the case only deals with the case where the TX & RX
+            // pins are on the same port. UART5 has them on different ports.
+            GPIO_InitTypeDef GPIO_InitStructure;
+            GPIO_InitStructure.Pin = MICROPY_HW_UART5_RX_PIN;
+            GPIO_InitStructure.Speed = GPIO_SPEED_HIGH;
+            GPIO_InitStructure.Mode = GPIO_MODE_AF_PP;
+            GPIO_InitStructure.Pull = GPIO_PULLUP;
+            GPIO_InitStructure.Alternate = GPIO_AF_UARTx;
+            HAL_GPIO_Init(MICROPY_HW_UART5_RX_PORT, &GPIO_InitStructure);
+            break;
+        #endif
+
         #if defined(MICROPY_HW_UART6_PORT) && defined(MICROPY_HW_UART6_PINS)
         // USART6 is on PC6/PC7 (CK on PC8)
         case PYB_UART_6:
@@ -596,6 +621,13 @@ STATIC mp_obj_t pyb_uart_deinit(mp_obj_t self_in) {
         __UART4_RELEASE_RESET();
         __UART4_CLK_DISABLE();
     #endif
+    #if defined(UART5)
+    } else if (uart->Instance == UART5) {
+        HAL_NVIC_DisableIRQ(UART5_IRQn);
+        __UART5_FORCE_RESET();
+        __UART5_RELEASE_RESET();
+        __UART5_CLK_DISABLE();
+    #endif
     } else if (uart->Instance == USART6) {
         HAL_NVIC_DisableIRQ(USART6_IRQn);
         __USART6_FORCE_RESET();