Detailed Description

NVRAM emulation using Internal Flash (flash_int driver)

Date: May 22, 2020

Functions
static void	backupInit ()

uint32_t	backupRamLoad (backup_ram_e idx)

void	backupRamSave (backup_ram_e idx, uint32_t value)

void	backupRamFlush (void)

Variables
static volatile uint32_t	backupRam [(int) LAST_BACKUP_RAM_ENUM+1]

static bool	wasLoaded = false

static const int	backupStateOffset = 0

static const int	backupDataOffset = 1

const size_t	backupSize = ((int)LAST_BACKUP_RAM_ENUM + 1) * sizeof(uint32_t)

Function Documentation

◆ backupInit()

static void backupInit ( )

static

Definition at line 23 of file backup_ram.cpp.

                         {
    static_assert(backupSize <= BACKUP_FLASH_SIZE, "Backup flash overflow");
    static_assert(BACKUP_FLASH_ADDR != (flashaddr_t)nullptr, "Backup address undefined");
 
    // first, load the whole buffer into the memory
    intFlashRead((flashaddr_t)BACKUP_FLASH_ADDR, (char *)backupRam, backupSize);
    // check if we have a reliable properly saved data
    if (backupRam[backupStateOffset] != BACKUP_SAVED) {
        // zero is the default value
        memset((void *)backupRam, 0, backupSize);
    }
 
    // we cannot trust the saved data anymore, until it's saved in backupRamFlush()
    // so we mark is as 'pending'
    backupRam[backupStateOffset] = BACKUP_PENDING;
    intFlashWrite((flashaddr_t)BACKUP_FLASH_ADDR + backupStateOffset, (char *)backupRam, sizeof(backupRam[backupStateOffset]));
 
    wasLoaded = true;
}

Referenced by backupRamLoad(), and backupRamSave().

Here is the call graph for this function:

Here is the caller graph for this function:

◆ backupRamFlush()

void backupRamFlush ( void )

Definition at line 61 of file backup_ram.cpp.

                          {
 
    // todo: implement an incremental "append-to-the-end" algorithm to minimize sector erasings?
 
    // Enter the critical zone
    syssts_t sts = chSysGetStatusAndLockX();
 
    // rewrite the whole sector
    intFlashErase((flashaddr_t)BACKUP_FLASH_ADDR, BACKUP_FLASH_SIZE);
    // mark the data as valid & saved
    backupRam[(int)backupStateOffset] = BACKUP_SAVED;
    // save the data to the flash
    intFlashWrite((flashaddr_t)BACKUP_FLASH_ADDR, (char *)backupRam, backupSize);
 
    // Leaving the critical zone
    chSysRestoreStatusX(sts);
 
    // there should not be any backup-RAM activity after this call
    // but if there is, at least try to reinitialize...
    wasLoaded = false;
}

◆ backupRamLoad()

uint32_t backupRamLoad ( backup_ram_e idx )

Definition at line 43 of file backup_ram.cpp.

                                         {
    // this is executed only once during the firmware init
    if (!wasLoaded) {
        backupInit();
    }
 
    return backupRam[(int)idx + backupDataOffset];
}

◆ backupRamSave()

void backupRamSave	(	backup_ram_e	idx,
		uint32_t	value
	)

Definition at line 52 of file backup_ram.cpp.

                                                     {
    // this is executed only once during the firmware init
    if (!wasLoaded) {
        backupInit();
    }
 
    backupRam[(int)idx + backupDataOffset] = value;
}