stm32: Add support for G4 MCUs, and add NUCLEO_G474RE board defn.

This commit adds support for the STM32G4 series of MCUs, and a board
definition for NUCLEO_G474RE.  This board has the REPL on LPUART1 which is
connected to the on-board ST-link USB-UART.

1 files changed, 36 insertions, 3 deletions

diff --git a/ports/stm32/flash.c b/ports/stm32/flash.c
index b926679f9..eeeab5204 100644
--- a/ports/stm32/flash.c
+++ b/ports/stm32/flash.c
@@ -97,7 +97,7 @@ static const flash_layout_t flash_layout[] = {
 };
 #endif
 
-#elif defined(STM32L0) || defined(STM32L4) || defined(STM32WB)
+#elif defined(STM32G4) || defined(STM32L0) || defined(STM32L4) || defined(STM32WB)
 
 static const flash_layout_t flash_layout[] = {
     { (uint32_t)FLASH_BASE, (uint32_t)FLASH_PAGE_SIZE, 512 },
@@ -126,12 +126,20 @@ static uint32_t get_bank(uint32_t addr) {
         if (addr < (FLASH_BASE + FLASH_BANK_SIZE)) {
             return FLASH_BANK_1;
         } else {
+            #if defined(FLASH_OPTR_DBANK)
             return FLASH_BANK_2;
+            #else
+            return 0;
+            #endif
         }
     } else {
         // bank swap
         if (addr < (FLASH_BASE + FLASH_BANK_SIZE)) {
+            #if defined(FLASH_OPTR_DBANK)
             return FLASH_BANK_2;
+            #else
+            return 0;
+            #endif
         } else {
             return FLASH_BANK_1;
         }
@@ -157,6 +165,25 @@ static uint32_t get_page(uint32_t addr) {
     return (addr - FLASH_BASE) / FLASH_PAGE_SIZE;
 }
 
+#elif defined(STM32G4)
+
+static uint32_t get_page(uint32_t addr) {
+    return (addr - FLASH_BASE) / FLASH_PAGE_SIZE;
+}
+
+static uint32_t get_bank(uint32_t addr) {
+    // no bank swap
+    if (addr < (FLASH_BASE + FLASH_BANK_SIZE)) {
+        return FLASH_BANK_1;
+    } else {
+        #if defined(FLASH_OPTR_DBANK)
+        return FLASH_BANK_2;
+        #else
+        return 0;
+        #endif
+    }
+}
+
 #endif
 
 bool flash_is_valid_addr(uint32_t addr) {
@@ -225,6 +252,12 @@ int flash_erase(uint32_t flash_dest, uint32_t num_word32) {
     EraseInitStruct.TypeErase = FLASH_TYPEERASE_PAGES;
     EraseInitStruct.PageAddress = flash_dest;
     EraseInitStruct.NbPages = (4 * num_word32 + FLASH_PAGE_SIZE - 4) / FLASH_PAGE_SIZE;
+    #elif defined(STM32G4)
+    __HAL_FLASH_CLEAR_FLAG(FLASH_FLAG_ALL_ERRORS);
+    EraseInitStruct.TypeErase = FLASH_TYPEERASE_PAGES;
+    EraseInitStruct.Page = get_page(flash_dest);
+    EraseInitStruct.Banks = get_bank(flash_dest);
+    EraseInitStruct.NbPages = (4 * num_word32 + FLASH_PAGE_SIZE - 4) / FLASH_PAGE_SIZE;
     #elif defined(STM32L0)
     __HAL_FLASH_CLEAR_FLAG(FLASH_FLAG_EOP | FLASH_FLAG_WRPERR | FLASH_FLAG_PGAERR);
     EraseInitStruct.TypeErase = FLASH_TYPEERASE_PAGES;
@@ -258,7 +291,7 @@ int flash_erase(uint32_t flash_dest, uint32_t num_word32) {
     #else
     EraseInitStruct.VoltageRange = 0; // unused parameter on STM32H7A3/B3
     #endif
-    #if defined(STM32H7)
+    #if defined(STM32G4) || defined(STM32H7)
     EraseInitStruct.Banks = get_bank(flash_dest);
     #endif
     EraseInitStruct.Sector = flash_get_sector_info(flash_dest, NULL, NULL);
@@ -337,7 +370,7 @@ int flash_write(uint32_t flash_dest, const uint32_t *src, uint32_t num_word32) {
 
     HAL_StatusTypeDef status = HAL_OK;
 
-    #if defined(STM32L4) || defined(STM32WB)
+    #if defined(STM32G4) || defined(STM32L4) || defined(STM32WB)
 
     // program the flash uint64 by uint64
     for (int i = 0; i < num_word32 / 2; i++) {