stm32: Add support for STM32N6xx MCUs.

This commit adds preliminary support for ST's new STM32N6xx MCUs.

Supported features of this MCU so far are:
- basic clock tree initialisation, running at 800MHz
- fully working USB
- XSPI in memory-mapped mode
- machine.Pin
- machine.UART
- RTC and deepsleep support
- SD card
- filesystem
- ROMFS
- WiFi and BLE via cyw43-driver (SDIO backend)

Note that the N6 does not have internal flash, and has some tricky boot
sequence, so using a custom bootloader (mboot) is almost a necessity.

Signed-off-by: Damien George <damien@micropython.org>

ports/stm32/storage.c

@@ -32,6 +32,7 @@
 #include "led.h"
 #include "storage.h"
 #include "irq.h"
+#include "xspi.h"
 
 #if MICROPY_HW_ENABLE_STORAGE
 
@@ -44,13 +45,17 @@
 
 static bool storage_is_initialised = false;
 
+#if !defined(STM32N6)
 static void storage_systick_callback(uint32_t ticks_ms);
+#endif
 
 void storage_init(void) {
     if (!storage_is_initialised) {
         storage_is_initialised = true;
 
+        #if !defined(STM32N6)
         systick_enable_dispatch(SYSTICK_DISPATCH_STORAGE, storage_systick_callback);
+        #endif
 
         MICROPY_HW_BDEV_IOCTL(BDEV_IOCTL_INIT, 0);
 
@@ -58,10 +63,12 @@ void storage_init(void) {
         MICROPY_HW_BDEV2_IOCTL(BDEV_IOCTL_INIT, 0);
         #endif
 
+        #if !defined(STM32N6)
         // Enable the flash IRQ, which is used to also call our storage IRQ handler
         // It must go at the same priority as USB (see comment in irq.h).
         NVIC_SetPriority(FLASH_IRQn, IRQ_PRI_FLASH);
         HAL_NVIC_EnableIRQ(FLASH_IRQn);
+        #endif
     }
 }
 
@@ -77,6 +84,7 @@ uint32_t storage_get_block_count(void) {
     #endif
 }
 
+#if !defined(STM32N6)
 static void storage_systick_callback(uint32_t ticks_ms) {
     if (STORAGE_IDLE_TICK(ticks_ms)) {
         // Trigger a FLASH IRQ to execute at a lower priority
@@ -96,6 +104,7 @@ void FLASH_IRQHandler(void) {
     #endif
     IRQ_EXIT(FLASH_IRQn);
 }
+#endif
 
 void storage_flush(void) {
     MICROPY_HW_BDEV_IOCTL(BDEV_IOCTL_SYNC, 0);
@@ -235,11 +244,11 @@ int storage_write_blocks(const uint8_t *src, uint32_t block_num, uint32_t num_bl
 // Board defined an external SPI flash for use with extended block protocol
 #define MICROPY_HW_BDEV_BLOCKSIZE_EXT (MP_SPIFLASH_ERASE_BLOCK_SIZE)
 #define MICROPY_HW_BDEV_READBLOCKS_EXT(dest, bl, off, len) \
-    (spi_bdev_readblocks_raw(MICROPY_HW_BDEV_SPIFLASH_EXTENDED, (dest), (bl), (off), (len)))
+    (spi_bdev_readblocks_raw(MICROPY_HW_BDEV_SPIFLASH_EXTENDED, (dest), MICROPY_HW_BDEV_SPIFLASH_OFFSET_BYTES / MP_SPIFLASH_ERASE_BLOCK_SIZE + (bl), (off), (len)))
 #define MICROPY_HW_BDEV_WRITEBLOCKS_EXT(src, bl, off, len) \
-    (spi_bdev_writeblocks_raw(MICROPY_HW_BDEV_SPIFLASH_EXTENDED, (src), (bl), (off), (len)))
+    (spi_bdev_writeblocks_raw(MICROPY_HW_BDEV_SPIFLASH_EXTENDED, (src), MICROPY_HW_BDEV_SPIFLASH_OFFSET_BYTES / MP_SPIFLASH_ERASE_BLOCK_SIZE + (bl), (off), (len)))
 #define MICROPY_HW_BDEV_ERASEBLOCKS_EXT(bl, len) \
-    (spi_bdev_eraseblocks_raw(MICROPY_HW_BDEV_SPIFLASH_EXTENDED, (bl), (len)))
+    (spi_bdev_eraseblocks_raw(MICROPY_HW_BDEV_SPIFLASH_EXTENDED, MICROPY_HW_BDEV_SPIFLASH_OFFSET_BYTES / MP_SPIFLASH_ERASE_BLOCK_SIZE + (bl), (len)))
 
 #elif (MICROPY_VFS_LFS1 || MICROPY_VFS_LFS2) && MICROPY_HW_ENABLE_INTERNAL_FLASH_STORAGE
 // Board uses littlefs and internal flash, so enable extended block protocol on internal flash