Rework MPU config for unaligned access to external memory

- Add MPU config to ORGPAL3 and ORGPALX to allow unaligned access to external memory.
- Remove MPU config for non cached memory in ChibiOS mcu config for ORGPAL3 and ORGPALX. Now are in Target_ConfigNonCacheableMemory().
- Rework call to MPU config in ORGPAL3 and ORGPALX.
- Migrate ST_STM32F769I_DISCOVERY MPU config to use ST HAL API.

Author: josesimoes

targets/ChibiOS/ORGPAL_PALTHREE/CMakeLists.txt

@@ -18,7 +18,8 @@ nf_setup_target_build(
     CLR_EXTRA_SOURCE_FILES
         # the next one is required is the target implements and it's using external memory
         ${CMAKE_CURRENT_SOURCE_DIR}/target_external_memory.c
-    
+        ${CMAKE_CURRENT_SOURCE_DIR}/target_mpu_config.c
+
     BOOTER_EXTRA_COMPILE_DEFINITIONS
         USBH_DEBUG_MULTI_HOST=0
 

targets/ChibiOS/ORGPAL_PALTHREE/nanoCLR/main.c

@@ -19,6 +19,7 @@
 
 extern int32_t hal_lfs_config();
 extern void hal_lfs_mount();
+extern void Target_ConfigMPU();
 
 // need to declare the Receiver thread here
 osThreadDef(ReceiverThread, osPriorityHigh, 2048, "ReceiverThread");
@@ -93,6 +94,9 @@ int main(void)
     crcStart(NULL);
 #endif
 
+    // MPU configuration
+    Target_ConfigMPU();
+
     // config and init external memory
     // this has to be called after osKernelInitialize, otherwise an hard fault will occur
     Target_ExternalMemoryInit();

targets/ChibiOS/ORGPAL_PALTHREE/nanoCLR/mcuconf.h

@@ -29,10 +29,7 @@
 /*
  * Memory attributes settings.
  */
-#define STM32_NOCACHE_ENABLE                TRUE
-#define STM32_NOCACHE_MPU_REGION            MPU_REGION_0
-#define STM32_NOCACHE_RBAR                  0x20000000U
-#define STM32_NOCACHE_RASR                  MPU_RASR_SIZE_128K
+#define STM32_NOCACHE_ENABLE                FALSE
 
 /*
  * HAL driver system settings.

targets/ChibiOS/ORGPAL_PALTHREE/target_external_memory.c

@@ -95,3 +95,46 @@ void Target_ExternalMemoryInit()
     fsmcSdramInit();
     fsmcSdramStart(&SDRAMD, &sdram_cfg);
 }
+
+void Target_ExternalMemoryConfigMPU()
+{
+    // ARM: STM32F7: hard fault caused by unaligned Memory Access
+    // reference https://www.keil.com/support/docs/3777%20%20.htm
+    // SYMPTOM
+    // If you use an STM32F7xx microcontroller with an external SDRAM,
+    // the Cortex-M7 core may unexpectedly run into the hard fault handler because of unaligned access.
+    // This may happen for example, when the frame buffer of an LCD, a RAM filesystem or any other data is
+    // located into the SDRAM address range 0xC0000000 - 0xC03FFFFF (max. 4MB).
+    // The hard fault is executed although the bit UNALIGN_TRP (bit 3) in the CCR register is not enabled.
+
+    // CAUSE
+    // In general, RAM accesses on Cortex-M7 based devices do not have to be aligned in any way.
+    // The Cortex-M7 core can handle unaligned accesses by hardware.
+    // Usually, variables should be naturally aligned because these accesses are slightly faster than unaligned
+    // accesses.
+
+    // STM32F7xx devices have the external SDRAM mapped to the
+    // address range 0xC0000000 - 0xC03FFFFF (max. 4MB).
+    // According to the ARMv7-M Architecture Reference Manual chapter B3.1 (table B3-1),
+    // the area 0xC0000000-0xDFFFFFFF (32MB) is specified as Device Memory Type.
+    // According to chapter A3.2.1, all accesses to Device Memory Types must be naturally aligned.
+    // If they are not, a hard fault will execute no matter if the bit UNALIGN_TRP (bit 3) in the CCR register is
+    // enabled or not.
+
+    MPU_Region_InitTypeDef MPU_InitStruct;
+
+    // Configure the MPU attributes for SDRAM
+    MPU_InitStruct.Enable = MPU_REGION_ENABLE;
+    MPU_InitStruct.BaseAddress = 0xD0000000;
+    MPU_InitStruct.Size = MPU_REGION_SIZE_8MB;
+    MPU_InitStruct.AccessPermission = MPU_REGION_FULL_ACCESS;
+    MPU_InitStruct.IsBufferable = MPU_ACCESS_NOT_BUFFERABLE;
+    MPU_InitStruct.IsCacheable = MPU_ACCESS_NOT_CACHEABLE;
+    MPU_InitStruct.IsShareable = MPU_ACCESS_NOT_SHAREABLE;
+    MPU_InitStruct.Number = MPU_REGION_NUMBER0;
+    MPU_InitStruct.TypeExtField = MPU_TEX_LEVEL1;
+    MPU_InitStruct.SubRegionDisable = 0x00;
+    MPU_InitStruct.DisableExec = MPU_INSTRUCTION_ACCESS_DISABLE;
+
+    HAL_MPU_ConfigRegion(&MPU_InitStruct);
+}

targets/ChibiOS/ORGPAL_PALTHREE/target_mpu_config.c

@@ -0,0 +1,45 @@
+//
+// Copyright (c) .NET Foundation and Contributors
+// See LICENSE file in the project root for full license information.
+//
+
+#include <ch.h>
+#include <hal.h>
+#include <stm32_registry.h>
+#include <hal_nf_community.h>
+
+extern void Target_ExternalMemoryConfigMPU();
+
+// SRAM1 base address
+#define SRAM1_BASE       0x20000000U
+#define SRAM1_SIZE_128K  (1UL << 16) // 2^17 bytes
+#define MPU_REGION_SRAM1 MPU_REGION_1
+
+void Target_ConfigNonCacheableMemory()
+{
+    // region
+    MPU->RNR = MPU_REGION_SRAM1;
+
+    // base address
+    MPU->RBAR = SRAM1_BASE;
+
+    // size and other configs
+    MPU->RASR =
+        ((uint32_t)MPU_RASR_ATTR_AP_RW_RW | MPU_RASR_ATTR_NON_CACHEABLE | MPU_RASR_ATTR_S | MPU_RASR_SIZE_128K |
+         MPU_RASR_ENABLE);
+}
+
+void Target_ConfigMPU()
+{
+    // disable MPU
+    HAL_MPU_Disable();
+
+    // config MPU for external memory
+    Target_ExternalMemoryConfigMPU();
+
+    // config MPU for non cacheable memory
+    Target_ConfigNonCacheableMemory();
+
+    // enable MPU
+    HAL_MPU_Enable(MPU_PRIVILEGED_DEFAULT);
+}

targets/ChibiOS/ORGPAL_PALX/CMakeLists.txt

@@ -18,6 +18,7 @@ nf_setup_target_build(
     CLR_EXTRA_SOURCE_FILES
         # the next one is required is the target implements and it's using external memory
         ${CMAKE_CURRENT_SOURCE_DIR}/target_external_memory.c
+        ${CMAKE_CURRENT_SOURCE_DIR}/target_mpu_config.c
 
     BOOTER_EXTRA_COMPILE_DEFINITIONS
         -DUSBH_DEBUG_MULTI_HOST=0

targets/ChibiOS/ORGPAL_PALX/nanoCLR/main.c

@@ -19,6 +19,7 @@
 
 extern int32_t hal_lfs_config();
 extern void hal_lfs_mount();
+extern void Target_ConfigMPU();
 
 // need to declare the Receiver thread here
 osThreadDef(ReceiverThread, osPriorityHigh, 2048, "ReceiverThread");
@@ -93,6 +94,9 @@ int main(void)
     crcStart(NULL);
 #endif
 
+    // MPU configuration
+    Target_ConfigMPU();
+
     // config and init external memory
     // this has to be called after osKernelInitialize, otherwise an hard fault will occur
     Target_ExternalMemoryInit();

targets/ChibiOS/ORGPAL_PALX/nanoCLR/mcuconf.h

@@ -27,10 +27,7 @@
 /*
  * Memory attributes settings.
  */
-#define STM32_NOCACHE_ENABLE                TRUE
-#define STM32_NOCACHE_MPU_REGION            MPU_REGION_0
-#define STM32_NOCACHE_RBAR                  0x20000000U
-#define STM32_NOCACHE_RASR                  MPU_RASR_SIZE_128K
+#define STM32_NOCACHE_ENABLE FALSE
 
 /*
  * HAL driver system settings.

targets/ChibiOS/ORGPAL_PALX/target_external_memory.c

@@ -69,8 +69,6 @@
 #define SDRAM_SIZE  (8 * 1024 * 1024)
 #define SDRAM_START ((void *)FSMC_Bank6_MAP_BASE)
 
-void SetupDeviceMemoryToEliminateUnalignedAccess();
-
 // SDRAM driver configuration structure.
 static const SDRAMConfig sdram_cfg = {
     .sdcr = (uint32_t)FMC_ColumnBits_Number_8b | FMC_RowBits_Number_12b | FMC_SDMemory_Width_16b |
@@ -94,12 +92,11 @@ static const SDRAMConfig sdram_cfg = {
 
 void Target_ExternalMemoryInit()
 {
-    SetupDeviceMemoryToEliminateUnalignedAccess();
     fsmcSdramInit();
     fsmcSdramStart(&SDRAMD, &sdram_cfg);
 }
 
-void SetupDeviceMemoryToEliminateUnalignedAccess()
+void Target_ExternalMemoryConfigMPU()
 {
     // ARM: STM32F7: hard fault caused by unaligned Memory Access
     // reference https://www.keil.com/support/docs/3777%20%20.htm
@@ -124,37 +121,20 @@ void SetupDeviceMemoryToEliminateUnalignedAccess()
     // If they are not, a hard fault will execute no matter if the bit UNALIGN_TRP (bit 3) in the CCR register is
     // enabled or not.
 
-    // Solution recommended by KEIL
-
-#define MPU_REGION_ENABLE              ((uint8_t)0x01U)
-#define MPU_REGION_SIZE_8MB            ((uint8_t)0x16U)
-#define MPU_REGION_FULL_ACCESS         ((uint8_t)0x03U)
-#define MPU_ACCESS_NOT_BUFFERABLE      ((uint8_t)0x00U)
-#define MPU_ACCESS_NOT_CACHEABLE       ((uint8_t)0x00U)
-#define MPU_ACCESS_NOT_SHAREABLE       ((uint8_t)0x00U)
-#define MPU_ACCESS_NOT_SHAREABLE       ((uint8_t)0x00U)
-#define MPU_REGION_NUMBER0             ((uint8_t)0x00U)
-#define MPU_TEX_LEVEL1                 ((uint8_t)0x01U)
-#define MPU_INSTRUCTION_ACCESS_DISABLE ((uint8_t)0x01U)
-#define MPU_PRIVILEGED_DEFAULT         ((uint32_t)0x00000004U)
-
-    // Disable the MPU
-    __DMB();
-    SCB->SHCSR &= ~SCB_SHCSR_MEMFAULTENA_Msk;
-    MPU->CTRL = 0;
-
-    // Configure the region
-    MPU->RNR = MPU_REGION_NUMBER0;
-    MPU->RBAR = 0xC0000000;
-    MPU->RASR = (MPU_INSTRUCTION_ACCESS_DISABLE << MPU_RASR_XN_Pos) | (MPU_REGION_FULL_ACCESS << MPU_RASR_AP_Pos) |
-                (MPU_TEX_LEVEL1 << 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) |
-                (0x00 << MPU_RASR_SRD_Pos) | (MPU_REGION_SIZE_8MB << MPU_RASR_SIZE_Pos) |
-                (MPU_REGION_ENABLE << MPU_RASR_ENABLE_Pos);
-
-    // Enable the MPU
-    MPU->CTRL = MPU_PRIVILEGED_DEFAULT | MPU_CTRL_ENABLE_Msk;
-    SCB->SHCSR |= SCB_SHCSR_MEMFAULTENA_Msk;
-    __DSB();
-    __ISB();
+    MPU_Region_InitTypeDef MPU_InitStruct;
+
+    // Configure the MPU attributes for SDRAM
+    MPU_InitStruct.Enable = MPU_REGION_ENABLE;
+    MPU_InitStruct.BaseAddress = 0xD0000000;
+    MPU_InitStruct.Size = MPU_REGION_SIZE_8MB;
+    MPU_InitStruct.AccessPermission = MPU_REGION_FULL_ACCESS;
+    MPU_InitStruct.IsBufferable = MPU_ACCESS_NOT_BUFFERABLE;
+    MPU_InitStruct.IsCacheable = MPU_ACCESS_NOT_CACHEABLE;
+    MPU_InitStruct.IsShareable = MPU_ACCESS_NOT_SHAREABLE;
+    MPU_InitStruct.Number = MPU_REGION_NUMBER0;
+    MPU_InitStruct.TypeExtField = MPU_TEX_LEVEL1;
+    MPU_InitStruct.SubRegionDisable = 0x00;
+    MPU_InitStruct.DisableExec = MPU_INSTRUCTION_ACCESS_DISABLE;
+
+    HAL_MPU_ConfigRegion(&MPU_InitStruct);
 }

targets/ChibiOS/ORGPAL_PALX/target_mpu_config.c

@@ -0,0 +1,45 @@
+//
+// Copyright (c) .NET Foundation and Contributors
+// See LICENSE file in the project root for full license information.
+//
+
+#include <ch.h>
+#include <hal.h>
+#include <stm32_registry.h>
+#include <hal_nf_community.h>
+
+extern void Target_ExternalMemoryConfigMPU();
+
+// SRAM1 base address
+#define SRAM1_BASE       0x20000000U
+#define SRAM1_SIZE_128K  (1UL << 16) // 2^17 bytes
+#define MPU_REGION_SRAM1 MPU_REGION_1
+
+void Target_ConfigNonCacheableMemory()
+{
+    // region
+    MPU->RNR = MPU_REGION_SRAM1;
+
+    // base address
+    MPU->RBAR = SRAM1_BASE;
+
+    // size and other configs
+    MPU->RASR =
+        ((uint32_t)MPU_RASR_ATTR_AP_RW_RW | MPU_RASR_ATTR_NON_CACHEABLE | MPU_RASR_ATTR_S | MPU_RASR_SIZE_128K |
+         MPU_RASR_ENABLE);
+}
+
+void Target_ConfigMPU()
+{
+    // disable MPU
+    HAL_MPU_Disable();
+
+    // config MPU for external memory
+    Target_ExternalMemoryConfigMPU();
+
+    // config MPU for non cacheable memory
+    Target_ConfigNonCacheableMemory();
+
+    // enable MPU
+    HAL_MPU_Enable(MPU_PRIVILEGED_DEFAULT);
+}