eeprom.c

/**
 ******************************************************************************
 * @file    EEPROM_Emulation/src/eeprom.c
 * @author  MCD Application Team
 * @version V1.0.0
 * @date    10-October-2011
 * @brief   This file provides all the EEPROM emulation firmware functions.
 ******************************************************************************
 * @attention
 *
 * THE PRESENT FIRMWARE WHICH IS FOR GUIDANCE ONLY AIMS AT PROVIDING CUSTOMERS
 * WITH CODING INFORMATION REGARDING THEIR PRODUCTS IN ORDER FOR THEM TO SAVE
 * TIME. AS A RESULT, STMICROELECTRONICS SHALL NOT BE HELD LIABLE FOR ANY
 * DIRECT, INDIRECT OR CONSEQUENTIAL DAMAGES WITH RESPECT TO ANY CLAIMS ARISING
 * FROM THE CONTENT OF SUCH FIRMWARE AND/OR THE USE MADE BY CUSTOMERS OF THE
 * CODING INFORMATION CONTAINED HEREIN IN CONNECTION WITH THEIR PRODUCTS.
 *
 * <h2><center>&copy; COPYRIGHT 2011 STMicroelectronics</center></h2>
 ******************************************************************************
 */

/** @addtogroup EEPROM_Emulation
 * @{
 */

/* Includes ------------------------------------------------------------------*/
#include "eeprom.h"
#include "flash_helper.h"

/* Private typedef -----------------------------------------------------------*/
/* Private define ------------------------------------------------------------*/
/* Private macro -------------------------------------------------------------*/
/* Private variables ---------------------------------------------------------*/

/* Global variable used to store variable value in read sequence */
uint16_t DataVar = 0;

/* Virtual address defined by the user: 0xFFFF value is prohibited */
extern uint16_t VirtAddVarTab[NB_OF_VAR];

/* Private function prototypes -----------------------------------------------*/
/* Private functions ---------------------------------------------------------*/
static FLASH_Status EE_Format(void);
static uint16_t EE_FindValidPage(uint8_t Operation);
static uint16_t EE_VerifyPageFullWriteVariable(uint16_t VirtAddress, uint16_t Data);
static uint16_t EE_PageTransfer(uint16_t VirtAddress, uint16_t Data);
static uint16_t EE_EraseSectorIfNotEmpty(uint32_t FLASH_Sector, uint8_t VoltageRange);

/**
 * @brief  Restore the pages to a known good state in case of page's status
 *   corruption after a power loss.
 * @param  None.
 * @retval - Flash error code: on write Flash error
 *         - FLASH_COMPLETE: on success
 */
uint16_t EE_Init(void)
{
	uint16_t PageStatus0 = 6, PageStatus1 = 6;
	uint16_t VarIdx = 0;
	uint16_t EepromStatus = 0, ReadStatus = 0;
	int16_t x = -1;
	uint16_t  FlashStatus;

	/* Get Page0 status */
	PageStatus0 = (*(__IO uint16_t*)PAGE0_BASE_ADDRESS);
	/* Get Page1 status */
	PageStatus1 = (*(__IO uint16_t*)PAGE1_BASE_ADDRESS);

	/* Check for invalid header states and repair if necessary */
	switch (PageStatus0)
	{
	case ERASED:
		if (PageStatus1 == VALID_PAGE) /* Page0 erased, Page1 valid */
		{
			/* Erase Page0 */
			FlashStatus = EE_EraseSectorIfNotEmpty(PAGE0_ID,VOLTAGE_RANGE);
			/* If erase operation was failed, a Flash error code is returned */
			if (FlashStatus != FLASH_COMPLETE)
			{
				return FlashStatus;
			}
		}
		else if (PageStatus1 == RECEIVE_DATA) /* Page0 erased, Page1 receive */
		{
			/* Erase Page0 */
			FlashStatus = EE_EraseSectorIfNotEmpty(PAGE0_ID, VOLTAGE_RANGE);
			/* If erase operation was failed, a Flash error code is returned */
			if (FlashStatus != FLASH_COMPLETE)
			{
				return FlashStatus;
			}
			/* Mark Page1 as valid */
			FlashStatus = FLASH_ProgramHalfWord(PAGE1_BASE_ADDRESS, VALID_PAGE);
			/* If program operation was failed, a Flash error code is returned */
			if (FlashStatus != FLASH_COMPLETE)
			{
				return FlashStatus;
			}
		}
		else /* First EEPROM access (Page0&1 are erased) or invalid state -> format EEPROM */
		{
			/* Erase both Page0 and Page1 and set Page0 as valid page */
			FlashStatus = EE_Format();
			/* If erase/program operation was failed, a Flash error code is returned */
			if (FlashStatus != FLASH_COMPLETE)
			{
				return FlashStatus;
			}
		}
		break;

	case RECEIVE_DATA:
		if (PageStatus1 == VALID_PAGE) /* Page0 receive, Page1 valid */
		{
			/* Transfer data from Page1 to Page0 */
			for (VarIdx = 0; VarIdx < NB_OF_VAR; VarIdx++)
			{
				if (( *(__IO uint16_t*)(PAGE0_BASE_ADDRESS + 6)) == VirtAddVarTab[VarIdx])
				{
					x = VarIdx;
				}
				if (VarIdx != x)
				{
					/* Read the last variables' updates */
					ReadStatus = EE_ReadVariable(VirtAddVarTab[VarIdx], &DataVar);
					/* In case variable corresponding to the virtual address was found */
					if (ReadStatus != 0x1)
					{
						/* Transfer the variable to the Page0 */
						EepromStatus = EE_VerifyPageFullWriteVariable(VirtAddVarTab[VarIdx], DataVar);
						/* If program operation was failed, a Flash error code is returned */
						if (EepromStatus != FLASH_COMPLETE)
						{
							return EepromStatus;
						}
					}
				}
			}
			/* Mark Page0 as valid */
			FlashStatus = FLASH_ProgramHalfWord(PAGE0_BASE_ADDRESS, VALID_PAGE);
			/* If program operation was failed, a Flash error code is returned */
			if (FlashStatus != FLASH_COMPLETE)
			{
				return FlashStatus;
			}
			/* Erase Page1 */
			FlashStatus = EE_EraseSectorIfNotEmpty(PAGE1_ID, VOLTAGE_RANGE);
			/* If erase operation was failed, a Flash error code is returned */
			if (FlashStatus != FLASH_COMPLETE)
			{
				return FlashStatus;
			}
		}
		else if (PageStatus1 == ERASED) /* Page0 receive, Page1 erased */
		{
			/* Erase Page1 */
			FlashStatus = EE_EraseSectorIfNotEmpty(PAGE1_ID, VOLTAGE_RANGE);
			/* If erase operation was failed, a Flash error code is returned */
			if (FlashStatus != FLASH_COMPLETE)
			{
				return FlashStatus;
			}
			/* Mark Page0 as valid */
			FlashStatus = FLASH_ProgramHalfWord(PAGE0_BASE_ADDRESS, VALID_PAGE);
			/* If program operation was failed, a Flash error code is returned */
			if (FlashStatus != FLASH_COMPLETE)
			{
				return FlashStatus;
			}
		}
		else /* Invalid state -> format eeprom */
		{
			/* Erase both Page0 and Page1 and set Page0 as valid page */
			FlashStatus = EE_Format();
			/* If erase/program operation was failed, a Flash error code is returned */
			if (FlashStatus != FLASH_COMPLETE)
			{
				return FlashStatus;
			}
		}
		break;

	case VALID_PAGE:
		if (PageStatus1 == VALID_PAGE) /* Invalid state -> format eeprom */
		{
			/* Erase both Page0 and Page1 and set Page0 as valid page */
			FlashStatus = EE_Format();
			/* If erase/program operation was failed, a Flash error code is returned */
			if (FlashStatus != FLASH_COMPLETE)
			{
				return FlashStatus;
			}
		}
		else if (PageStatus1 == ERASED) /* Page0 valid, Page1 erased */
		{
			/* Erase Page1 */
			FlashStatus = EE_EraseSectorIfNotEmpty(PAGE1_ID, VOLTAGE_RANGE);
			/* If erase operation was failed, a Flash error code is returned */
			if (FlashStatus != FLASH_COMPLETE)
			{
				return FlashStatus;
			}
		}
		else /* Page0 valid, Page1 receive */
		{
			/* Transfer data from Page0 to Page1 */
			for (VarIdx = 0; VarIdx < NB_OF_VAR; VarIdx++)
			{
				if ((*(__IO uint16_t*)(PAGE1_BASE_ADDRESS + 6)) == VirtAddVarTab[VarIdx])
				{
					x = VarIdx;
				}
				if (VarIdx != x)
				{
					/* Read the last variables' updates */
					ReadStatus = EE_ReadVariable(VirtAddVarTab[VarIdx], &DataVar);
					/* In case variable corresponding to the virtual address was found */
					if (ReadStatus != 0x1)
					{
						/* Transfer the variable to the Page1 */
						EepromStatus = EE_VerifyPageFullWriteVariable(VirtAddVarTab[VarIdx], DataVar);
						/* If program operation was failed, a Flash error code is returned */
						if (EepromStatus != FLASH_COMPLETE)
						{
							return EepromStatus;
						}
					}
				}
			}
			/* Mark Page1 as valid */
			FlashStatus = FLASH_ProgramHalfWord(PAGE1_BASE_ADDRESS, VALID_PAGE);
			/* If program operation was failed, a Flash error code is returned */
			if (FlashStatus != FLASH_COMPLETE)
			{
				return FlashStatus;
			}
			/* Erase Page0 */
			FlashStatus = EE_EraseSectorIfNotEmpty(PAGE0_ID, VOLTAGE_RANGE);
			/* If erase operation was failed, a Flash error code is returned */
			if (FlashStatus != FLASH_COMPLETE)
			{
				return FlashStatus;
			}
		}
		break;

	default:  /* Any other state -> format eeprom */
		/* Erase both Page0 and Page1 and set Page0 as valid page */
		FlashStatus = EE_Format();
		/* If erase/program operation was failed, a Flash error code is returned */
		if (FlashStatus != FLASH_COMPLETE)
		{
			return FlashStatus;
		}
		break;
	}

	return FLASH_COMPLETE;
}

/**
 * @brief  Returns the last stored variable data, if found, which correspond to
 *   the passed virtual address
 * @param  VirtAddress: Variable virtual address
 * @param  Data: Global variable contains the read variable value
 * @retval Success or error status:
 *           - 0: if variable was found
 *           - 1: if the variable was not found
 *           - NO_VALID_PAGE: if no valid page was found.
 */
uint16_t EE_ReadVariable(uint16_t VirtAddress, uint16_t* Data)
{
	uint16_t ValidPage = PAGE0;
	uint16_t AddressValue = 0x5555, ReadStatus = 1;
	uint32_t Address = EEPROM_START_ADDRESS, PageStartAddress = EEPROM_START_ADDRESS;

	/* Get active Page for read operation */
	ValidPage = EE_FindValidPage(READ_FROM_VALID_PAGE);

	/* Check if there is no valid page */
	if (ValidPage == NO_VALID_PAGE)
	{
		return  NO_VALID_PAGE;
	}

	/* Get the valid Page start Address */
	PageStartAddress = (uint32_t)(EEPROM_START_ADDRESS + (uint32_t)(ValidPage * PAGE_SIZE));

	/* Get the valid Page end Address */
	Address = (uint32_t)((EEPROM_START_ADDRESS - 2) + (uint32_t)((1 + ValidPage) * PAGE_SIZE));

	/* Check each active page address starting from end */
	while (Address > (PageStartAddress + 2))
	{
		/* Get the current location content to be compared with virtual address */
		AddressValue = (*(__IO uint16_t*)Address);

		/* Compare the read address with the virtual address */
		if (AddressValue == VirtAddress)
		{
			/* Get content of Address-2 which is variable value */
			*Data = (*(__IO uint16_t*)(Address - 2));

			/* In case variable value is read, reset ReadStatus flag */
			ReadStatus = 0;

			break;
		}
		else
		{
			/* Next address location */
			Address = Address - 4;
		}
	}

	/* Return ReadStatus value: (0: variable exist, 1: variable doesn't exist) */
	return ReadStatus;
}

/**
 * @brief  Writes/upadtes variable data in EEPROM.
 * @param  VirtAddress: Variable virtual address
 * @param  Data: 16 bit data to be written
 * @retval Success or error status:
 *           - FLASH_COMPLETE: on success
 *           - PAGE_FULL: if valid page is full
 *           - NO_VALID_PAGE: if no valid page was found
 *           - Flash error code: on write Flash error
 */
uint16_t EE_WriteVariable(uint16_t VirtAddress, uint16_t Data)
{
	uint16_t Status = 0;

	/* Write the variable virtual address and value in the EEPROM */
	Status = EE_VerifyPageFullWriteVariable(VirtAddress, Data);

	/* In case the EEPROM active page is full */
	if (Status == PAGE_FULL)
	{
		/* Perform Page transfer */
		Status = EE_PageTransfer(VirtAddress, Data);
	}

	/* Return last operation status */
	return Status;
}

/**
 * @brief  Erases PAGE and PAGE1 and writes VALID_PAGE header to PAGE
 * @param  None
 * @retval Status of the last operation (Flash write or erase) done during
 *         EEPROM formating
 */
static FLASH_Status EE_Format(void)
{
	FLASH_Status FlashStatus = FLASH_COMPLETE;

	/* Erase Page0 */
	FlashStatus = EE_EraseSectorIfNotEmpty(PAGE0_ID, VOLTAGE_RANGE);

	/* If erase operation was failed, a Flash error code is returned */
	if (FlashStatus != FLASH_COMPLETE)
	{
		return FlashStatus;
	}

	/* Set Page0 as valid page: Write VALID_PAGE at Page0 base address */
	FlashStatus = FLASH_ProgramHalfWord(PAGE0_BASE_ADDRESS, VALID_PAGE);

	/* If program operation was failed, a Flash error code is returned */
	if (FlashStatus != FLASH_COMPLETE)
	{
		return FlashStatus;
	}

	/* Erase Page1 */
	FlashStatus = EE_EraseSectorIfNotEmpty(PAGE1_ID, VOLTAGE_RANGE);

	/* Return Page1 erase operation status */
	return FlashStatus;
}

/**
 * @brief  Find valid Page for write or read operation
 * @param  Operation: operation to achieve on the valid page.
 *   This parameter can be one of the following values:
 *     @arg READ_FROM_VALID_PAGE: read operation from valid page
 *     @arg WRITE_IN_VALID_PAGE: write operation from valid page
 * @retval Valid page number (PAGE or PAGE1) or NO_VALID_PAGE in case
 *   of no valid page was found
 */
static uint16_t EE_FindValidPage(uint8_t Operation)
{
	uint16_t PageStatus0 = 6, PageStatus1 = 6;

	/* Get Page0 actual status */
	PageStatus0 = (*(__IO uint16_t*)PAGE0_BASE_ADDRESS);

	/* Get Page1 actual status */
	PageStatus1 = (*(__IO uint16_t*)PAGE1_BASE_ADDRESS);

	/* Write or read operation */
	switch (Operation)
	{
	case WRITE_IN_VALID_PAGE:   /* ---- Write operation ---- */
		if (PageStatus1 == VALID_PAGE)
		{
			/* Page0 receiving data */
			if (PageStatus0 == RECEIVE_DATA)
			{
				return PAGE0;         /* Page0 valid */
			}
			else
			{
				return PAGE1;         /* Page1 valid */
			}
		}
		else if (PageStatus0 == VALID_PAGE)
		{
			/* Page1 receiving data */
			if (PageStatus1 == RECEIVE_DATA)
			{
				return PAGE1;         /* Page1 valid */
			}
			else
			{
				return PAGE0;         /* Page0 valid */
			}
		}
		else
		{
			return NO_VALID_PAGE;   /* No valid Page */
		}

	case READ_FROM_VALID_PAGE:  /* ---- Read operation ---- */
		if (PageStatus0 == VALID_PAGE)
		{
			return PAGE0;           /* Page0 valid */
		}
		else if (PageStatus1 == VALID_PAGE)
		{
			return PAGE1;           /* Page1 valid */
		}
		else
		{
			return NO_VALID_PAGE ;  /* No valid Page */
		}

	default:
		return PAGE0;             /* Page0 valid */
	}
}

/**
 * @brief  Verify if active page is full and Writes variable in EEPROM.
 * @param  VirtAddress: 16 bit virtual address of the variable
 * @param  Data: 16 bit data to be written as variable value
 * @retval Success or error status:
 *           - FLASH_COMPLETE: on success
 *           - PAGE_FULL: if valid page is full
 *           - NO_VALID_PAGE: if no valid page was found
 *           - Flash error code: on write Flash error
 */
static uint16_t EE_VerifyPageFullWriteVariable(uint16_t VirtAddress, uint16_t Data)
{
	FLASH_Status FlashStatus = FLASH_COMPLETE;
	uint16_t ValidPage = PAGE0;
	uint32_t Address = EEPROM_START_ADDRESS, PageEndAddress = EEPROM_START_ADDRESS+PAGE_SIZE;

	/* Get valid Page for write operation */
	ValidPage = EE_FindValidPage(WRITE_IN_VALID_PAGE);

	/* Check if there is no valid page */
	if (ValidPage == NO_VALID_PAGE)
	{
		return  NO_VALID_PAGE;
	}

	/* Get the valid Page start Address */
	Address = (uint32_t)(EEPROM_START_ADDRESS + (uint32_t)(ValidPage * PAGE_SIZE));

	/* Get the valid Page end Address */
	PageEndAddress = (uint32_t)((EEPROM_START_ADDRESS - 2) + (uint32_t)((1 + ValidPage) * PAGE_SIZE));

	/* Check each active page address starting from begining */
	while (Address < PageEndAddress)
	{
		/* Verify if Address and Address+2 contents are 0xFFFFFFFF */
		if ((*(__IO uint32_t*)Address) == 0xFFFFFFFF)
		{
			/* Set variable data */
			FlashStatus = FLASH_ProgramHalfWord(Address, Data);
			/* If program operation was failed, a Flash error code is returned */
			if (FlashStatus != FLASH_COMPLETE)
			{
				return FlashStatus;
			}
			/* Set variable virtual address */
			FlashStatus = FLASH_ProgramHalfWord(Address + 2, VirtAddress);
			/* Return program operation status */
			return FlashStatus;
		}
		else
		{
			/* Next address location */
			Address = Address + 4;
		}
	}

	/* Return PAGE_FULL in case the valid page is full */
	return PAGE_FULL;
}

/**
 * @brief  Transfers last updated variables data from the full Page to
 *   an empty one.
 * @param  VirtAddress: 16 bit virtual address of the variable
 * @param  Data: 16 bit data to be written as variable value
 * @retval Success or error status:
 *           - FLASH_COMPLETE: on success
 *           - PAGE_FULL: if valid page is full
 *           - NO_VALID_PAGE: if no valid page was found
 *           - Flash error code: on write Flash error
 */
static uint16_t EE_PageTransfer(uint16_t VirtAddress, uint16_t Data)
{
	FLASH_Status FlashStatus = FLASH_COMPLETE;
	uint32_t NewPageAddress = EEPROM_START_ADDRESS;
	uint16_t OldPageId=0;
	uint16_t ValidPage = PAGE0, VarIdx = 0;
	uint16_t EepromStatus = 0, ReadStatus = 0;

	/* Get active Page for read operation */
	ValidPage = EE_FindValidPage(READ_FROM_VALID_PAGE);

	if (ValidPage == PAGE1)       /* Page1 valid */
	{
		/* New page address where variable will be moved to */
		NewPageAddress = PAGE0_BASE_ADDRESS;

		/* Old page ID where variable will be taken from */
		OldPageId = PAGE1_ID;
	}
	else if (ValidPage == PAGE0)  /* Page0 valid */
	{
		/* New page address  where variable will be moved to */
		NewPageAddress = PAGE1_BASE_ADDRESS;

		/* Old page ID where variable will be taken from */
		OldPageId = PAGE0_ID;
	}
	else
	{
		return NO_VALID_PAGE;       /* No valid Page */
	}

	/* Set the new Page status to RECEIVE_DATA status */
	FlashStatus = FLASH_ProgramHalfWord(NewPageAddress, RECEIVE_DATA);
	/* If program operation was failed, a Flash error code is returned */
	if (FlashStatus != FLASH_COMPLETE)
	{
		return FlashStatus;
	}

	/* Write the variable passed as parameter in the new active page */
	EepromStatus = EE_VerifyPageFullWriteVariable(VirtAddress, Data);
	/* If program operation was failed, a Flash error code is returned */
	if (EepromStatus != FLASH_COMPLETE)
	{
		return EepromStatus;
	}

	/* Transfer process: transfer variables from old to the new active page */
	for (VarIdx = 0; VarIdx < NB_OF_VAR; VarIdx++)
	{
		if (VirtAddVarTab[VarIdx] != VirtAddress)  /* Check each variable except the one passed as parameter */
		{
			/* Read the other last variable updates */
			ReadStatus = EE_ReadVariable(VirtAddVarTab[VarIdx], &DataVar);
			/* In case variable corresponding to the virtual address was found */
			if (ReadStatus != 0x1)
			{
				/* Transfer the variable to the new active page */
				EepromStatus = EE_VerifyPageFullWriteVariable(VirtAddVarTab[VarIdx], DataVar);
				/* If program operation was failed, a Flash error code is returned */
				if (EepromStatus != FLASH_COMPLETE)
				{
					return EepromStatus;
				}
			}
		}
	}

	/* Erase the old Page: Set old Page status to ERASED status */
	FlashStatus = EE_EraseSectorIfNotEmpty(OldPageId, VOLTAGE_RANGE);
	/* If erase operation was failed, a Flash error code is returned */
	if (FlashStatus != FLASH_COMPLETE)
	{
		return FlashStatus;
	}

	/* Set new Page status to VALID_PAGE status */
	FlashStatus = FLASH_ProgramHalfWord(NewPageAddress, VALID_PAGE);
	/* If program operation was failed, a Flash error code is returned */
	if (FlashStatus != FLASH_COMPLETE)
	{
		return FlashStatus;
	}

	/* Return last operation flash status */
	return FlashStatus;
}

/*
 * Erase flash page if it is not already erased. This is to save write cycles and
 * prevent the memory from getting erased in case of unstable voltage at boot.
 */
static uint16_t EE_EraseSectorIfNotEmpty(uint32_t FLASH_Sector, uint8_t VoltageRange) {
	uint8_t *addr = flash_helper_get_sector_address(FLASH_Sector);

	for (unsigned int i = 0;i < PAGE_SIZE;i++) {
		if (addr[i] != 0xFF) {
			return FLASH_EraseSector(FLASH_Sector, VoltageRange);
		}
	}

	return FLASH_COMPLETE;
}

/**
 * @}
 */

/******************* (C) COPYRIGHT 2011 STMicroelectronics *****END OF FILE****/