STM32F4 FLASH update

Add critical section in
- flash_erase_sector and
- flash_program_page
to make FLASH erase procedure interrupt safe
(can occur with Ethernet)

Author: jeromecoutant

targets/TARGET_STM/TARGET_STM32F4/flash_api.c

@@ -21,9 +21,6 @@
 #include "flash_data.h"
 #include "platform/mbed_critical.h"
 
-// This file is automatically generated
-
-
 static uint32_t GetSector(uint32_t Address);
 static uint32_t GetSectorSize(uint32_t Sector);
 
@@ -37,30 +34,8 @@ int32_t flash_free(flash_t *obj)
     return 0;
 }
 
-static int32_t flash_unlock(void)
-{
-    /* Allow Access to Flash control registers and user Falsh */
-    if (HAL_FLASH_Unlock()) {
-        return -1;
-    } else {
-        return 0;
-    }
-}
-
-static int32_t flash_lock(void)
-{
-    /* Disable the Flash option control register access (recommended to protect
-    the option Bytes against possible unwanted operations) */
-    if (HAL_FLASH_Lock()) {
-        return -1;
-    } else {
-        return 0;
-    }
-}
-
 int32_t flash_erase_sector(flash_t *obj, uint32_t address)
 {
-    /*Variable used for Erase procedure*/
     static FLASH_EraseInitTypeDef EraseInitStruct;
     uint32_t FirstSector;
     uint32_t SectorError = 0;
@@ -70,10 +45,12 @@ int32_t flash_erase_sector(flash_t *obj, uint32_t address)
         return -1;
     }
 
-    if (flash_unlock() != HAL_OK) {
+    if (HAL_FLASH_Unlock() != HAL_OK) {
         return -1;
     }
 
+    core_util_critical_section_enter();
+
     /* Get the 1st sector to erase */
     FirstSector = GetSector(address);
 
@@ -86,7 +63,9 @@ int32_t flash_erase_sector(flash_t *obj, uint32_t address)
         status = -1;
     }
 
-    flash_lock();
+    core_util_critical_section_exit();
+
+    HAL_FLASH_Lock();
 
     return status;
 }
@@ -99,10 +78,11 @@ int32_t flash_program_page(flash_t *obj, uint32_t address, const uint8_t *data,
         return -1;
     }
 
-    if (flash_unlock() != HAL_OK) {
+    if (HAL_FLASH_Unlock() != HAL_OK) {
         return -1;
     }
 
+    core_util_critical_section_enter();
     /* Note: If an erase operation in Flash memory also concerns data in the data or instruction cache,
        you have to make sure that these data are rewritten before they are accessed during code
        execution. If this cannot be done safely, it is recommended to flush the caches by setting the
@@ -126,7 +106,9 @@ int32_t flash_program_page(flash_t *obj, uint32_t address, const uint8_t *data,
         }
     }
 
-    flash_lock();
+    core_util_critical_section_exit();
+
+    HAL_FLASH_Lock();
 
     return status;
 }