flash.c

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/*
 * Copyright (c) 2017, James Jackson and Daniel Koch, BYU MAGICC Lab
 *
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *
 * * Redistributions of source code must retain the above copyright notice, this
 *   list of conditions and the following disclaimer.
 *
 * * Redistributions in binary form must reproduce the above copyright notice,
 *   this list of conditions and the following disclaimer in the documentation
 *   and/or other materials provided with the distribution.
 *
 * * Neither the name of the copyright holder nor the names of its
 *   contributors may be used to endorse or promote products derived from
 *   this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
 * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
 * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */
#include <string.h>

#include <breezystm32.h>

#include "flash.h"

void initEEPROM(void)
{
  // make sure (at compile time) that config struct doesn't overflow allocated flash pages
  // ct_assert(sizeof(_params) < CONFIG_SIZE);
}

static uint8_t compute_checksum(const void * addr, size_t len)
{
  const uint8_t *p;
  uint8_t chk = 0;

  for (p = (const uint8_t *)addr; p < ((const uint8_t *)addr + len); p++)
    chk ^= *p;

  return chk;
}

bool readEEPROM(void * dest, size_t len)
{
  memcpy(dest, (char *)FLASH_WRITE_ADDR, len);
  return true;
}

bool writeEEPROM(const void * src, size_t len)
{
  FLASH_Status status;

  // write it
  FLASH_Unlock();
  for (unsigned int tries = 3; tries; tries--)
  {
    FLASH_ClearFlag(FLASH_FLAG_EOP | FLASH_FLAG_PGERR | FLASH_FLAG_WRPRTERR);

    for(int i = 0; i < NUM_PAGES; i++)
      status = FLASH_ErasePage(FLASH_WRITE_ADDR + i * FLASH_PAGE_SIZE);

    for (unsigned int i = 0; i < len && status == FLASH_COMPLETE; i += 4)
      status = FLASH_ProgramWord(FLASH_WRITE_ADDR + i, *(uint32_t *)((char *)src + i));

    if(status == FLASH_COMPLETE)
      break;
  }
  FLASH_Lock();

  // Flash write failed - just die now
  if (status != FLASH_COMPLETE || compute_checksum(src, len) != compute_checksum((uint32_t*)FLASH_WRITE_ADDR, len))
    return false;

  return true;
}