void memory_protect(void) {
#if MEMORY_PROTECT
// Reference STM32F205 Flash programming manual revision 5
// http://www.st.com/resource/en/programming_manual/cd00233952.pdf Section 2.6
// Option bytes
// set RDP level 2 WRP for sectors 0 and
// 1 flash option control register matches
if (((FLASH_OPTION_BYTES_1 & 0xFFEC) == 0xCCEC) &&
((FLASH_OPTION_BYTES_2 & 0xFFF) == 0xFFC) &&
(FLASH_OPTCR == 0x0FFCCCED)) {
return; // already set up correctly - bail out
}
for (int i = FLASH_STORAGE_SECTOR_FIRST; i <= FLASH_STORAGE_SECTOR_LAST;
i++) {
flash_erase_sector(i, FLASH_CR_PROGRAM_X32);
}
flash_unlock_option_bytes();
// Section 2.8.6 Flash option control register (FLASH_OPTCR)
// Bits 31:28 Reserved, must be kept cleared.
// Bits 27:16 nWRP: Not write protect: write protect bootloader code in
// flash main memory sectors 0 and 1 (Section 2.3; table 2) Bits 15:8 RDP:
// Read protect: level 2 chip read protection active Bits 7:5 USER: User
// option bytes: no reset on standby, no reset on stop, software watchdog
// Bit 4 Reserved, must be kept cleared.
// Bits 3:2 BOR_LEV: BOR reset Level: BOR off
// Bit 1 OPTSTRT: Option start: ignored by flash_program_option_bytes
// Bit 0 OPTLOCK: Option lock: ignored by flash_program_option_bytes
flash_program_option_bytes(0x0FFCCCEC);
flash_lock_option_bytes();
#endif
}
void flash_program_option_bytes(u32 data)
{
flash_wait_for_last_operation();
if (FLASH_OPTCR & FLASH_OPTLOCK)
flash_unlock_option_bytes();
FLASH_OPTCR = data & ~0x3;
FLASH_OPTCR |= FLASH_OPTSTRT; /* Enable option byte programming. */
flash_wait_for_last_operation();
}
void flash_program_option_bytes(u32 address, u16 data)
{
flash_wait_for_last_operation();
if ((FLASH_CR & FLASH_CR_OPTWRE) == 0)
flash_unlock_option_bytes();
FLASH_CR |= FLASH_CR_OPTPG; /* Enable option byte programming. */
(*(volatile u16 *)address) = data;
flash_wait_for_last_operation();
FLASH_CR &= ~FLASH_CR_OPTPG; /* Disable option byte programming. */
}
void flash_erase_option_bytes(void)
{
flash_wait_for_last_operation();
if ((FLASH_CR & FLASH_CR_OPTWRE) == 0)
flash_unlock_option_bytes();
FLASH_CR |= FLASH_CR_OPTER; /* Enable option byte erase. */
FLASH_CR |= FLASH_CR_STRT;
flash_wait_for_last_operation();
FLASH_CR &= ~FLASH_CR_OPTER; /* Disable option byte erase. */
}
void flash_program_option_bytes(uint32_t address, uint16_t data)
{
flash_wait_for_last_operation();
if ((FLASH_CR & FLASH_CR_OPTWRE) == 0) {
flash_unlock_option_bytes();
}
FLASH_CR |= FLASH_CR_OPTPG; /* Enable option byte programming. */
MMIO16(address) = data;
flash_wait_for_last_operation();
FLASH_CR &= ~FLASH_CR_OPTPG; /* Disable option byte programming. */
}
/** Unlock a sector of the STM flash memory.
* Locked sectors can not be erased or programmed.
*
* \param sector Number of the sector to unlock.
* \return Error code
*/
u8 stm_flash_unlock_sector(u8 sector)
{
/* Check that sector argument is valid. */
if (sector >= STM_FLASH_N_SECTORS)
return FLASH_INVALID_SECTOR;
flash_unlock_option_bytes();
while (FLASH_SR & FLASH_SR_BSY) ;
FLASH_OPTCR |= (1 << (16+sector));
FLASH_OPTCR |= FLASH_OPTCR_OPTSTRT;
while (FLASH_SR & FLASH_SR_BSY) ;
return FLASH_OK;
}
void memory_unlock(void) {
#ifndef EMULATOR
// This exercises a bug in the STM32F2 that allows writing to read-only
// sectors of flash.
flash_unlock_option_bytes();
#ifdef DEBUG_ON
// 0xFFFAAEC: remove wp from all sectors, no RDP (unless previously set to level 2 which is irreversible),
// disable configurable resets. Low order two bits are don't care.
flash_program_option_bytes(0x0FFFAAEC);
#else
// Even though level 2 is described as sticky, this chip has a proven bug related to this register so
// to be sure rewrite the level two value for RDP for non-debug builds.
flash_program_option_bytes(0x0FFFCCEC);
#endif
flash_lock_option_bytes();
#endif
}
/*
* memory_protect() - Set option bytes for memory protection
*
* INPUT
* none
* OUTPUT
* none
*/
void memory_protect(void)
{
#ifndef EMULATOR
/* set RDP level 2 WRP for sectors 0,5,6 */
if((((*OPTION_BYTES_1) & 0xFFFF) == OPTION_RDP) && (((*OPTION_BYTES_2) & 0xFFFF) == OPTION_WRP))
{
return; // already set up correctly - bail out
}
flash_unlock_option_bytes();
/* WRP + RDP */
#if !defined(DEBUG_ON) // safety check to make sure mem protect disabled in debug builds
flash_program_option_bytes((uint32_t)OPTION_WRP << 16 | OPTION_RDP); //RDP BLevel 2 (Irreversible)
#endif
flash_lock_option_bytes();
#else
printf("memory protect ON\n");
#endif
}
// Remove write-protection on all flash sectors.
//
// This is an undocumented feature/bug of STM32F205/F405 microcontrollers,
// where flash controller reads its write protection bits from FLASH_OPTCR
// register not from OPTION_BYTES, rendering write protection useless.
// This behaviour is fixed in future designs of flash controller used for
// example in STM32F427, where the protection bits are read correctly
// from OPTION_BYTES and not form FLASH_OPCTR register.
//
// Read protection is unaffected and always stays locked to the desired value.
void memory_write_unlock(void) {
flash_unlock_option_bytes();
flash_program_option_bytes(0x0FFFCCEC);
flash_lock_option_bytes();
}