openblt_flash.cpp

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#include "pch.h"
#include "flash_int.h"
 
extern "C" {
    #include "boot.h"
    #include "flash.h"
}
 
#ifdef STM32H7XX
//Since a 10-bit ECC code is associated to each 256-bit data Flash word,
//only write operations by 256 bits are executed in the non-volatile memory.
#define FLASH_ECC_LINE_SIZE     (256 / 8)
 
static blt_int8u flashBuffer[FLASH_ECC_LINE_SIZE];
static blt_addr flashAddr = 0x0;
 
#define FLASH_WRITE_STEP        FLASH_ECC_LINE_SIZE
#define FLASH_WRITE_ADDR_MASK   (~(FLASH_WRITE_STEP - 1))
 
static void FlashBufferReset()
{
    memset(flashBuffer, 0xff, sizeof(flashBuffer));
    flashAddr = 0;
}
 
static blt_bool FlashBufferFlush()
{
    if (flashAddr == 0x0) {
        return BLT_TRUE;
    }
 
    int result = intFlashWrite(flashAddr, (const char*)flashBuffer, sizeof(flashBuffer));
 
    FlashBufferReset();
 
    return (result == FLASH_RETURN_SUCCESS) ? BLT_TRUE : BLT_FALSE;
}
 
static blt_bool FlashBufferedWrite(blt_addr addr, blt_int32u len, blt_int8u *data)
{
    while (len) {
        if ((addr & FLASH_WRITE_ADDR_MASK) != flashAddr) {
            // crossing ECC line boundary
            FlashBufferFlush();
 
            flashAddr = addr & FLASH_WRITE_ADDR_MASK;
        }
 
        off_t off = addr - flashAddr;
        size_t chunk = minI(sizeof(flashBuffer) - off, len);
        memcpy(flashBuffer + off, data, chunk);
 
        addr += chunk;
        data += chunk;
        len -= chunk;
    }
 
    return BLT_TRUE;
}
 
#endif
 
void FlashInit() {
    // Flash already init by ChibiOS
#ifdef STM32H7XX
    FlashBufferReset();
#endif
}
 
blt_addr FlashGetUserProgBaseAddress() {
#ifdef STM32H7XX
    return FLASH_BASE + 128 * 1024;
#else // not STM32H7
    return FLASH_BASE + 32 * 1024;
#endif
}
 
blt_bool FlashWrite(blt_addr addr, blt_int32u len, blt_int8u *data) {
    // don't allow overwriting the bootloader
    if (addr < FlashGetUserProgBaseAddress()) {
        return BLT_FALSE;
    }
 
#ifdef STM32H7XX
    return FlashBufferedWrite(addr, len, data);
#else // not STM32H7
    return (FLASH_RETURN_SUCCESS == intFlashWrite(addr, (const char*)data, len)) ? BLT_TRUE : BLT_FALSE;
#endif
}
 
blt_bool FlashErase(blt_addr addr, blt_int32u len) {
    // don't allow erasing the bootloader
    if (addr < FlashGetUserProgBaseAddress()) {
        return BLT_FALSE;
    }
 
    if (!intFlashIsErased(addr, len)) {
        return (FLASH_RETURN_SUCCESS == intFlashErase(addr, len)) ? BLT_TRUE : BLT_FALSE;
    }
 
    return BLT_TRUE;
}
 
blt_bool FlashDone() {
#ifdef STM32H7XX
    FlashBufferFlush();
#endif
    return BLT_TRUE;
}
 
blt_bool FlashWriteChecksum() {
    return BLT_TRUE;
}
 
blt_bool FlashVerifyChecksum() {
    // Naive check: if the first block is blank, there's no code there
    if (intFlashIsErased(FlashGetUserProgBaseAddress(), 4)) {
        return BLT_FALSE;
    }
 
    static const size_t checksumOffset = 0x1C;
 
    // Now do the actual CRC check to ensure we didn't get stuck with a half-written firmware image
    uint8_t* start = reinterpret_cast<uint8_t*>(FlashGetUserProgBaseAddress());
 
    size_t imageSize = *reinterpret_cast<size_t*>(start + checksumOffset + 4);
 
    if (imageSize > 1024 * 1024) {
        // impossibly large size, invalid
        return BLT_FALSE;
    }
 
    // part before checksum+size
    uint32_t calcChecksum = crc32(start, checksumOffset);
    // part after checksum+size
    calcChecksum = crc32inc(start + checksumOffset + 4, calcChecksum, imageSize - (checksumOffset + 4));
 
    uint32_t storedChecksum = *reinterpret_cast<uint32_t*>(start + checksumOffset);
 
    return calcChecksum == storedChecksum ? BLT_TRUE : BLT_FALSE;
}
 
blt_bool isFlashDualBank(void) {
#ifdef STM32F7XX
    // cleared bit indicates dual bank
    return (FLASH->OPTCR & FLASH_OPTCR_nDBANK) == 0 ? BLT_TRUE : BLT_FALSE;
#else
    return BLT_TRUE;
#endif
}