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>

1 files changed, 16 insertions, 4 deletions

diff --git a/ports/stm32/mpu.h b/ports/stm32/mpu.h
index 5756cb056..8713fe837 100644
--- a/ports/stm32/mpu.h
+++ b/ports/stm32/mpu.h
@@ -137,18 +137,26 @@ static inline void mpu_config_end(uint32_t irq_state) {
     enable_irq(irq_state);
 }
 
-#elif defined(STM32H5)
+#elif defined(STM32H5) || defined(STM32N6)
 
 #define MPU_REGION_SIG      (MPU_REGION_NUMBER0)
 #define MPU_REGION_ETH      (MPU_REGION_NUMBER1)
-#define MPU_REGION_LAST_USED (MPU_REGION_NUMBER1)
+#define MPU_REGION_DMA_UNCACHED_1 (MPU_REGION_NUMBER2)
+#define MPU_REGION_DMA_UNCACHED_2 (MPU_REGION_NUMBER3)
+#define MPU_REGION_LAST_USED (MPU_REGION_NUMBER3)
 
 #define ST_DEVICE_SIGNATURE_BASE (0x08fff800)
 #define ST_DEVICE_SIGNATURE_LIMIT (0x08ffffff)
 
 // STM32H5 Cortex-M33 MPU works differently from older cores.
 // Macro only takes region size in bytes, Attributes are coded in mpu_config_region().
+#define MPU_CONFIG_DISABLE (0)
 #define MPU_CONFIG_ETH(size) (size)
+#define MPU_CONFIG_UNCACHED(size) (size)
+
+#if defined(STM32N6)
+#define MPU_REGION_SIZE_32B (32)
+#endif
 
 static inline void mpu_init(void) {
     // Configure attribute 0, inner-outer non-cacheable (=0x44).
@@ -180,8 +188,12 @@ static inline uint32_t mpu_config_start(void) {
 }
 
 static inline void mpu_config_region(uint32_t region, uint32_t base_addr, uint32_t size) {
-    if (region == MPU_REGION_ETH) {
-        // Configure region 1 to make DMA memory non-cacheable.
+    if (size == 0) {
+        // Disable MPU for this region.
+        MPU->RNR = region;
+        MPU->RLAR &= ~MPU_RLAR_EN_Msk;
+    } else if (region == MPU_REGION_ETH || region == MPU_REGION_DMA_UNCACHED_1 || region == MPU_REGION_DMA_UNCACHED_2) {
+        // Configure region to make DMA memory non-cacheable.
 
         __DMB();
         // Configure attribute 1, inner-outer non-cacheable (=0x44).