LibrePilot/flight/pios/stm32f0x/pios_eeprom.c

/**
 ******************************************************************************
 * @addtogroup PIOS PIOS Core hardware abstraction layer
 * @{
 * @addtogroup PIOS_EEPROM EEPROM reading/writing functions
 * @brief PIOS EEPROM reading/writing functions
 * @{
 *
 * @file       pios_eeprom.c
 * @author     The OpenPilot Team, http://www.openpilot.org Copyright (C) 2012.
 * @brief      COM layer functions
 * @see        The GNU Public License (GPL) Version 3
 *
 *****************************************************************************/
/*
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
 * or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
 * for more details.
 *
 * You should have received a copy of the GNU General Public License along
 * with this program; if not, write to the Free Software Foundation, Inc.,
 * 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
 */

#include <pios.h>

#ifdef PIOS_INCLUDE_FLASH_EEPROM

#include <stm32f10x_flash.h>
#include <pios_board_info.h>

static struct pios_eeprom_cfg config;

/**
 * Initialize the flash eeprom device
 * \param cfg     The configuration structure.
 */
void PIOS_EEPROM_Init(const struct pios_eeprom_cfg *cfg)
{
    config = *cfg;
}

/**
 * Save a block of data to the flash eeprom device.
 * \param data  A pointer to the data to write.
 * \param len   The length of data to write.
 * \return      0 on sucess
 */
int32_t PIOS_EEPROM_Save(uint8_t *data, uint32_t len)
{
    // We need to write 32 bit words, so extend the length to be an even multiple of 4 bytes,
    // and include 4 bytes for the 32 bit CRC.
    uint32_t nwords = (len / 4) + 1 + (len % 4 ? 1 : 0);
    uint32_t size   = nwords * 4;

    // Ensure that the length is not longer than the max size.
    if (size > config.max_size) {
        return -1;
    }

    // Calculate a 32 bit CRC of the data.
    uint32_t crc = PIOS_CRC32_updateCRC(0xffffffff, data, len);

    // Unlock the Flash Program Erase controller
    FLASH_Unlock();

    // See if we have to write the data.
    if ((memcmp(data, (uint8_t *)config.base_address, len) == 0) &&
        (memcmp((uint8_t *)&crc, (uint8_t *)config.base_address + size - 4, 4) == 0)) {
        return 0;
    }

    // TODO: Check that the area isn't already erased

    // Erase page
    FLASH_Status fs = FLASH_ErasePage(config.base_address);
    if (fs != FLASH_COMPLETE) { // error
        FLASH_Lock();
        return -2;
    }

    // write 4 bytes at a time into program flash area (emulated EEPROM area)
    uint8_t *p1  = data;
    uint32_t *p3 = (uint32_t *)config.base_address;
    for (uint32_t i = 0; i < size; p3++) {
        uint32_t value = 0;

        if (i == (size - 4)) {
            // write the CRC.
            value = crc;
            i    += 4;
        } else {
            if (i < len) {
                value |= (uint32_t)*p1++ << 0;
            } else { value |= 0x000000ff; }
            i++;
            if (i < len) {
                value |= (uint32_t)*p1++ << 8;
            } else { value |= 0x0000ff00; }
            i++;
            if (i < len) {
                value |= (uint32_t)*p1++ << 16;
            } else { value |= 0x00ff0000; }
            i++;
            if (i < len) {
                value |= (uint32_t)*p1++ << 24;
            } else { value |= 0xff000000; }
            i++;
        }

        // write a 32-bit value
        fs = FLASH_ProgramWord((uint32_t)p3, value);
        if (fs != FLASH_COMPLETE) {
            FLASH_Lock();
            return -3;
        }
    }

    // Lock the Flash Program Erase controller
    FLASH_Lock();

    return 0;
}

/**
 * Reads a block of data from the flash eeprom device.
 * \param data  A pointer to the output data buffer.
 * \param len   The length of data to read.
 * \return      0 on sucess
 */
int32_t PIOS_EEPROM_Load(uint8_t *data, uint32_t len)
{
    // We need to write 32 bit words, so the length should have been extended
    // to an even multiple of 4 bytes, and should include 4 bytes for the 32 bit CRC.
    uint32_t nwords = (len / 4) + 1 + (len % 4 ? 1 : 0);
    uint32_t size   = nwords * 4;

    // Ensure that the length is not longer than the max size.
    if (size > config.max_size) {
        return -1;
    }

    // Read the data from flash.
    memcpy(data, (uint8_t *)config.base_address, len);

    // Read the CRC.
    uint32_t crc_flash = *((uint32_t *)(config.base_address + size - 4));

    // Calculate a 32 bit CRC of the data.
    uint32_t crc = PIOS_CRC32_updateCRC(0xffffffff, data, len);
    if (crc != crc_flash) {
        return -2;
    }

    return 0;
}

#endif /* PIOS_INCLUDE_FLASH_EEPROM */