stm32/mpu: Add helper functions for configuring MPU.

ports/stm32/main.c

@@ -43,6 +43,7 @@
 #include "drivers/cyw43/cyw43.h"
 #endif
 
+#include "mpu.h"
 #include "systick.h"
 #include "pendsv.h"
 #include "powerctrl.h"
@@ -409,6 +410,8 @@ void stm32_main(uint32_t reset_mode) {
 
     #endif
 
+    mpu_init();
+
     #if __CORTEX_M >= 0x03
     // Set the priority grouping
     NVIC_SetPriorityGrouping(NVIC_PRIORITYGROUP_4);

ports/stm32/mpu.h

@@ -0,0 +1,74 @@
+/*
+ * This file is part of the MicroPython project, http://micropython.org/
+ *
+ * The MIT License (MIT)
+ *
+ * Copyright (c) 2019 Damien P. George
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+#ifndef MICROPY_INCLUDED_STM32_MPU_H
+#define MICROPY_INCLUDED_STM32_MPU_H
+
+#if defined(STM32F7) || defined(STM32H7)
+
+#define MPU_CONFIG_DISABLE(srd, size) ( \
+    MPU_INSTRUCTION_ACCESS_DISABLE  << MPU_RASR_XN_Pos \
+    | MPU_REGION_NO_ACCESS          << MPU_RASR_AP_Pos \
+    | MPU_TEX_LEVEL0                << MPU_RASR_TEX_Pos \
+    | MPU_ACCESS_NOT_SHAREABLE      << MPU_RASR_S_Pos \
+    | MPU_ACCESS_NOT_CACHEABLE      << MPU_RASR_C_Pos \
+    | MPU_ACCESS_NOT_BUFFERABLE     << MPU_RASR_B_Pos \
+    | (srd)                         << MPU_RASR_SRD_Pos \
+    | (size)                        << MPU_RASR_SIZE_Pos \
+    | MPU_REGION_ENABLE             << MPU_RASR_ENABLE_Pos \
+    )
+
+static inline void mpu_init(void) {
+    MPU->CTRL = MPU_PRIVILEGED_DEFAULT | MPU_CTRL_ENABLE_Msk;
+    SCB->SHCSR |= SCB_SHCSR_MEMFAULTENA_Msk;
+    __DSB();
+    __ISB();
+}
+
+static inline void mpu_config_start(void) {
+    __disable_irq();
+}
+
+static inline void mpu_config_region(uint32_t region, uint32_t base_addr, uint32_t attr_size) {
+    MPU->RNR = region;
+    MPU->RBAR = base_addr;
+    MPU->RASR = attr_size;
+}
+
+static inline void mpu_config_end(void) {
+    __ISB();
+    __DSB();
+    __DMB();
+    __enable_irq();
+}
+
+#else
+
+static inline void mpu_init(void) {
+}
+
+#endif
+
+#endif // MICROPY_INCLUDED_STM32_MPU_H