nand.c

Go to the documentation of this file.

#include "nand.h"
#include <cfg/log.h>
#include <struct/heap.h>
#include <string.h> // memset


/*
 * Remap info written in the first page of each block.
 *
 * This structure is used in blocks of the reserved area to store
 * which block the block containing the structure is remapping.
 * It's stored in all other blocks too to mark a formatted block.
 * In this case the member mapped_blk has non meaning.
 */
struct RemapInfo
{
    uint32_t tag;         // Magic number to detect valid info
    uint16_t mapped_blk;  // Bad block the block containing this info is remapping
};

// Where RemapInfo is stored in the spare area
#define NAND_REMAP_TAG_OFFSET  (CONFIG_NAND_SPARE_SIZE - sizeof(struct RemapInfo))

// Fixed tag to detect RemapInfo
#define NAND_REMAP_TAG         0x3e10c8ed

/*
 * Number of ECC words computed for a page.
 *
 * For 2048 bytes pages and 1 ECC word each 256 bytes,
 * 24 bytes of ECC data are stored.
 */
#define NAND_ECC_NWORDS        (CONFIG_NAND_DATA_SIZE / 256)

// Total page size (user data + spare) in bytes
#define NAND_PAGE_SIZE         (CONFIG_NAND_DATA_SIZE + CONFIG_NAND_SPARE_SIZE)

// Erase block size in bytes
#define NAND_BLOCK_SIZE        (CONFIG_NAND_DATA_SIZE * CONFIG_NAND_PAGES_PER_BLOCK)

// Number of usable blocks, and index of first remapping block
#define NAND_NUM_USER_BLOCKS   (CONFIG_NAND_NUM_BLOCK - CONFIG_NAND_NUM_REMAP_BLOCKS)

// ONFI NAND status codes
#define NAND_STATUS_READY  BV(6)
#define NAND_STATUS_ERROR  BV(0)


// Get block from page
#define PAGE(blk)            ((blk) * CONFIG_NAND_PAGES_PER_BLOCK)

// Page from block and page in block
#define BLOCK(page)          ((uint16_t)((page) / CONFIG_NAND_PAGES_PER_BLOCK))
#define PAGE_IN_BLOCK(page)  ((uint16_t)((page) % CONFIG_NAND_PAGES_PER_BLOCK))


/*
 * Translate page index plus a byte offset
 * in the five address cycles format needed by NAND.
 *
 * Cycles in x8 mode.
 * CA = column addr, PA = page addr, BA = block addr
 *
 * Cycle    I/O7  I/O6  I/O5  I/O4  I/O3  I/O2  I/O1  I/O0
 * -------------------------------------------------------
 * First    CA7   CA6   CA5   CA4   CA3   CA2   CA1   CA0
 * Second   LOW   LOW   LOW   LOW   CA11  CA10  CA9   CA8
 * Third    BA7   BA6   PA5   PA4   PA3   PA2   PA1   PA0
 * Fourth   BA15  BA14  BA13  BA12  BA11  BA10  BA9   BA8
 * Fifth    LOW   LOW   LOW   LOW   LOW   LOW   LOW   BA16
 */
static void getAddrCycles(uint32_t page, uint16_t offset, uint32_t *cycle0, uint32_t *cycle1234)
{
    ASSERT(offset < NAND_PAGE_SIZE);

    *cycle0 = offset & 0xff;
    *cycle1234 = (page << 8) | ((offset >> 8) & 0xf);
}


static void chipReset(Nand *chip)
{
    nand_sendCommand(chip, NAND_CMD_RESET, 0, 0, 0, 0);
    nand_waitReadyBusy(chip, CONFIG_NAND_TMOUT);
}


static bool isOperationComplete(Nand *chip)
{
    uint8_t status;

    nand_sendCommand(chip, NAND_CMD_STATUS, 0, 0, 0, 0);

    status = nand_getChipStatus(chip);
    return (status & NAND_STATUS_READY) && !(status & NAND_STATUS_ERROR);
}


int nand_blockErase(Nand *chip, uint16_t block)
{
    uint32_t cycle0;
    uint32_t cycle1234;

    uint16_t remapped_block = chip->block_map[block];
    if (block != remapped_block)
    {
        LOG_INFO("nand_blockErase: remapped block: blk %d->%d\n", block, remapped_block);
        block = remapped_block;
    }

    getAddrCycles(PAGE(block), 0, &cycle0, &cycle1234);

    nand_sendCommand(chip, NAND_CMD_ERASE_1, NAND_CMD_ERASE_2, 3, 0, cycle1234 >> 8);

    nand_waitReadyBusy(chip, CONFIG_NAND_TMOUT);

    if (!isOperationComplete(chip))
    {
        LOG_ERR("nand: error erasing block\n");
        chip->status |= NAND_ERR_ERASE;
        return -1;
    }

    return 0;
}


bool nand_getDevId(Nand *chip, uint8_t dev_id[5])
{
    nand_sendCommand(chip, NAND_CMD_READID, 0, 1, 0, 0);

    nand_waitReadyBusy(chip, CONFIG_NAND_TMOUT);
    if (!nand_waitTransferComplete(chip, CONFIG_NAND_TMOUT))
    {
        LOG_ERR("nand: getDevId timeout\n");
        chip->status |= NAND_ERR_RD_TMOUT;
        return false;
    }

    memcpy(dev_id, nand_dataBuffer(chip), sizeof(dev_id));
    return true;
}


static bool nand_readPage(Nand *chip, uint32_t page, uint16_t offset)
{
    uint32_t cycle0;
    uint32_t cycle1234;

    //LOG_INFO("nand_readPage: page 0x%lx off 0x%x\n", page, offset);

    getAddrCycles(page, offset, &cycle0, &cycle1234);

    nand_sendCommand(chip, NAND_CMD_READ_1, NAND_CMD_READ_2, 5, cycle0, cycle1234);

    nand_waitReadyBusy(chip, CONFIG_NAND_TMOUT);
    if (!nand_waitTransferComplete(chip, CONFIG_NAND_TMOUT))
    {
        LOG_ERR("nand: read timeout\n");
        chip->status |= NAND_ERR_RD_TMOUT;
        return false;
    }

    return true;
}


/*
 * Read page data and ECC, checking for errors.
 * TODO: fix errors with ECC when possible.
 */
static bool nand_read(Nand *chip, uint32_t page, void *buf, uint16_t offset, uint16_t size)
{
    struct RemapInfo remap_info;
    uint32_t remapped_page = PAGE(chip->block_map[BLOCK(page)]) + PAGE_IN_BLOCK(page);

    //LOG_INFO("nand_read: page=%ld, offset=%d, size=%d\n", page, offset, size);

    if (page != remapped_page)
    {
        LOG_INFO("nand_read: remapped block: blk %d->%d, pg %ld->%ld\n",
                BLOCK(page), chip->block_map[BLOCK(page)], page, remapped_page);
        page = remapped_page;
    }

    if (!nand_readPage(chip, page, 0))
        return false;

    memcpy(buf, (char *)nand_dataBuffer(chip) + offset, size);

    /*
     * Check for ECC hardware status only if a valid RemapInfo structure is found.
     * That guarantees the page is written by us and a valid ECC is present.
     */
    memcpy(&remap_info, (char *)buf + NAND_REMAP_TAG_OFFSET, sizeof(remap_info));
    if (remap_info.tag == NAND_REMAP_TAG && !nand_checkEcc(chip))
    {
        chip->status |= NAND_ERR_ECC;
        return false;
    }
    else
        return true;
}


/*
 * Write data stored in nand_dataBuffer() to a NAND page, starting at a given offset.
 * Usually offset will be 0 to write data or CONFIG_NAND_DATA_SIZE to write the spare
 * area.
 */
static bool nand_writePage(Nand *chip, uint32_t page, uint16_t offset)
{
    uint32_t cycle0;
    uint32_t cycle1234;

    //LOG_INFO("nand_writePage: page 0x%lx off 0x%x\n", page, offset);

    getAddrCycles(page, offset, &cycle0, &cycle1234);

    nand_sendCommand(chip, NAND_CMD_WRITE_1, 0, 5, cycle0, cycle1234);

    if (!nand_waitTransferComplete(chip, CONFIG_NAND_TMOUT))
    {
        LOG_ERR("nand: write timeout\n");
        chip->status |= NAND_ERR_WR_TMOUT;
        return false;
    }

    nand_sendCommand(chip, NAND_CMD_WRITE_2, 0, 0, 0, 0);

    nand_waitReadyBusy(chip, CONFIG_NAND_TMOUT);

    if (!isOperationComplete(chip))
    {
        LOG_ERR("nand: error writing page\n");
        chip->status |= NAND_ERR_WRITE;
        return false;
    }

    return true;
}


/*
 * Write data, ECC and remap block info.
 *
 * \param page           the page to be written
 * \parma original_page  if different from page, it's the page that's being remapped
 *
 * Implementation note for SAM3 NFC controller:
 * according to datasheet to get ECC computed by hardware is sufficient
 * to write the main area.  But it seems that in that way the last ECC_PR
 * register is not generated.  The workaround is to write data and dummy (ff)
 * spare data in one write, at this point the last ECC_PR is correct and
 * ECC data can be written in the spare area with a second program operation.
 */
static bool nand_write(Nand *chip, uint32_t page, const void *buf, size_t size)
{
    struct RemapInfo remap_info;
    uint32_t *nand_buf = (uint32_t *)nand_dataBuffer(chip);
    uint32_t remapped_page = PAGE(chip->block_map[BLOCK(page)]) + PAGE_IN_BLOCK(page);

    ASSERT(size <= CONFIG_NAND_DATA_SIZE);

    if (page != remapped_page)
        LOG_INFO("nand_write: remapped block: blk %d->%d, pg %ld->%ld\n",
                BLOCK(page), chip->block_map[BLOCK(page)], page, remapped_page);

    // Data
    memset(nand_buf, 0xff, NAND_PAGE_SIZE);
    memcpy(nand_buf, buf, size);
    if (!nand_writePage(chip, remapped_page, 0))
        return false;

    // ECC
    memset(nand_buf, 0xff, CONFIG_NAND_SPARE_SIZE);
    nand_computeEcc(chip, buf, size, nand_buf, NAND_ECC_NWORDS);

    // Remap info
    remap_info.tag = NAND_REMAP_TAG;
    remap_info.mapped_blk = BLOCK(page);
    memcpy((char *)nand_buf + NAND_REMAP_TAG_OFFSET, &remap_info, sizeof(remap_info));

    return nand_writePage(chip, remapped_page, CONFIG_NAND_DATA_SIZE);
}


/*
 * Check if the given block is marked bad: ONFI standard mandates
 * that bad block are marked with "00" bytes on the spare area of the
 * first page in block.
 */
static bool blockIsGood(Nand *chip, uint16_t blk)
{
    uint8_t *first_byte = (uint8_t *)nand_dataBuffer(chip);
    bool good;

    // Check first byte in spare area of first page in block
    nand_readPage(chip, PAGE(blk), CONFIG_NAND_DATA_SIZE);
    good = *first_byte != 0;

    if (!good)
        LOG_INFO("nand: bad block %d\n", blk);

    return good;
}


/*
 * Return the main partition block remapped on given block in the remap
 * partition (dest_blk).
 */
static int getBadBlockFromRemapBlock(Nand *chip, uint16_t dest_blk)
{
    struct RemapInfo *remap_info = (struct RemapInfo *)nand_dataBuffer(chip);

    if (!nand_readPage(chip, PAGE(dest_blk), CONFIG_NAND_DATA_SIZE + NAND_REMAP_TAG_OFFSET))
        return -1;

    if (remap_info->tag == NAND_REMAP_TAG)
        return remap_info->mapped_blk;
    else
        return -1;
}


/*
 * Set a block remapping: src_blk (a block in main data partition) is remapped
 * on dest_blk (block in reserved remapped blocks partition).
 */
static bool setMapping(Nand *chip, uint32_t src_blk, uint32_t dest_blk)
{
    struct RemapInfo *remap_info = (struct RemapInfo *)nand_dataBuffer(chip);

    LOG_INFO("nand, setMapping(): src=%ld dst=%ld\n", src_blk, dest_blk);

    if (!nand_readPage(chip, PAGE(dest_blk), CONFIG_NAND_DATA_SIZE + NAND_REMAP_TAG_OFFSET))
        return false;

    remap_info->tag = NAND_REMAP_TAG;
    remap_info->mapped_blk = src_blk;

    return nand_writePage(chip, PAGE(dest_blk), CONFIG_NAND_DATA_SIZE + NAND_REMAP_TAG_OFFSET);
}


/*
 * Get a new block from the remap partition to use as a substitute
 * for a bad block.
 */
static uint16_t getFreeRemapBlock(Nand *chip)
{
    int blk;

    for (blk = chip->remap_start; blk < CONFIG_NAND_NUM_BLOCK; blk++)
    {
        if (blockIsGood(chip, blk))
        {
            chip->remap_start = blk + 1;
            return blk;
        }
    }

    LOG_ERR("nand: reserved blocks for bad block remapping exhausted!\n");
    return 0;
}


/*
 * Check if NAND is initialized.
 */
static bool chipIsMarked(Nand *chip)
{
    return getBadBlockFromRemapBlock(chip, NAND_NUM_USER_BLOCKS) != -1;
}


/*
 * Initialize NAND (format). Scan NAND for factory marked bad blocks.
 * All found bad blocks are remapped to the remap partition: each
 * block in the remap partition used to remap bad blocks is marked.
 */
static void initBlockMap(Nand *chip)
{
    int b, last;

    // Default is for each block to not be remapped
    for (b = 0; b < CONFIG_NAND_NUM_BLOCK; b++)
        chip->block_map[b] = b;
    chip->remap_start = NAND_NUM_USER_BLOCKS;

    if (chipIsMarked(chip))
    {
        LOG_INFO("nand: found initialized NAND, searching for remapped blocks\n");

        // Scan for assigned blocks in remap area
        for (b = last = NAND_NUM_USER_BLOCKS; b < CONFIG_NAND_NUM_BLOCK; b++)
        {
            int remapped_blk = getBadBlockFromRemapBlock(chip, b);
            if (remapped_blk != -1 && remapped_blk != b)
            {
                LOG_INFO("nand: found remapped block %d->%d\n", remapped_blk, b);
                chip->block_map[remapped_blk] = b;
                last = b + 1;
            }
        }
        chip->remap_start = last;
    }
    else
    {
        bool remapped_anything = false;

        LOG_INFO("nand: found new NAND, searching for bad blocks\n");

        for (b = 0; b < NAND_NUM_USER_BLOCKS; b++)
        {
            if (!blockIsGood(chip, b))
            {
                chip->block_map[b] = getFreeRemapBlock(chip);
                setMapping(chip, b, chip->block_map[b]);
                remapped_anything = true;
                LOG_WARN("nand: found new bad block %d, remapped to %d\n", b, chip->block_map[b]);
            }
        }

        /*
         * If no bad blocks are found (we're lucky!) write anyway a dummy
         * remap to mark NAND and detect we already scanned it next time.
         */
        if (!remapped_anything)
        {
            setMapping(chip, NAND_NUM_USER_BLOCKS, NAND_NUM_USER_BLOCKS);
            LOG_INFO("nand: no bad block founds, marked NAND\n");
        }
    }
}


void nand_format(Nand *chip)
{
    int b;

    for (b = 0; b < CONFIG_NAND_NUM_BLOCK; b++)
    {
        LOG_INFO("nand: erasing block %d\n", b);
        chip->block_map[b] = b;
        nand_blockErase(chip, b);
    }
    chip->remap_start = NAND_NUM_USER_BLOCKS;
}

#ifdef _DEBUG

/*
 * Create some bad blocks, erasing them and writing the bad block mark.
 */
void nand_ruinSomeBlocks(Nand *chip)
{
    int bads[] = { 7, 99, 555, 1003, 1004, 1432 };
    unsigned i;

    LOG_INFO("nand: erasing mark\n");
    nand_blockErase(chip, NAND_NUM_USER_BLOCKS);

    for (i = 0; i < countof(bads); i++)
    {
        LOG_INFO("nand: erasing block %d\n", bads[i]);
        nand_blockErase(chip, bads[i]);

        LOG_INFO("nand: marking page %d as bad\n", PAGE(bads[i]));
        memset(nand_dataBuffer(chip), 0, CONFIG_NAND_SPARE_SIZE);
        nand_writePage(chip, PAGE(bads[i]), CONFIG_NAND_DATA_SIZE);
    }
}

#endif

static bool commonInit(Nand *chip, struct Heap *heap, unsigned chip_select)
{
    memset(chip, 0, sizeof(Nand));

    DB(chip->fd.priv.type = KBT_NAND);
    chip->fd.blk_size = NAND_BLOCK_SIZE;
    chip->fd.blk_cnt  = NAND_NUM_USER_BLOCKS;

    chip->chip_select = chip_select;
    chip->block_map = heap_allocmem(heap, CONFIG_NAND_NUM_BLOCK * sizeof(*chip->block_map));
    if (!chip->block_map)
    {
        LOG_ERR("nand: error allocating block map\n");
        return false;
    }

    nand_hwInit(chip);
    chipReset(chip);
    initBlockMap(chip);

    return true;
}


/**************** Kblock interface ****************/


static size_t nand_writeDirect(struct KBlock *kblk, block_idx_t idx, const void *buf, size_t offset, size_t size)
{
    ASSERT(offset <= NAND_BLOCK_SIZE);
    ASSERT(offset % CONFIG_NAND_DATA_SIZE == 0);
    ASSERT(size <= NAND_BLOCK_SIZE);
    ASSERT(size % CONFIG_NAND_DATA_SIZE == 0);

    LOG_INFO("nand_writeDirect: idx=%ld offset=%d size=%d\n", idx, offset, size);

    nand_blockErase(NAND_CAST(kblk), idx);

    while (offset < size)
    {
        uint32_t page = PAGE(idx) + (offset / CONFIG_NAND_DATA_SIZE);

        if (!nand_write(NAND_CAST(kblk), page, buf, CONFIG_NAND_DATA_SIZE))
            break;

        offset += CONFIG_NAND_DATA_SIZE;
        buf = (const char *)buf + CONFIG_NAND_DATA_SIZE;
    }

    return offset;
}


static size_t nand_readDirect(struct KBlock *kblk, block_idx_t idx, void *buf, size_t offset, size_t size)
{
    uint32_t page;
    size_t   read_size;
    size_t   read_offset;
    size_t   nread = 0;

    ASSERT(offset < NAND_BLOCK_SIZE);
    ASSERT(size <= NAND_BLOCK_SIZE);

    LOG_INFO("nand_readDirect: idx=%ld offset=%d size=%d\n", idx, offset, size);

    while (nread < size)
    {
        page        = PAGE(idx) + (offset / CONFIG_NAND_DATA_SIZE);
        read_offset = offset % CONFIG_NAND_DATA_SIZE;
        read_size   = MIN(size, CONFIG_NAND_DATA_SIZE - read_offset);

        if (!nand_read(NAND_CAST(kblk), page, (char *)buf + nread, read_offset, read_size))
            break;

        offset += read_size;
        nread  += read_size;
    }

    return nread;
}


static int nand_error(struct KBlock *kblk)
{
    Nand *chip = NAND_CAST(kblk);
    return chip->status;
}


static void nand_clearError(struct KBlock *kblk)
{
    Nand *chip = NAND_CAST(kblk);
    chip->status = 0;
}


static const KBlockVTable nand_buffered_vt =
{
    .readDirect = nand_readDirect,
    .writeDirect = nand_writeDirect,

    .readBuf = kblock_swReadBuf,
    .writeBuf = kblock_swWriteBuf,
    .load = kblock_swLoad,
    .store = kblock_swStore,

    .error = nand_error,
    .clearerr = nand_clearError,
};

static const KBlockVTable nand_unbuffered_vt =
{
    .readDirect = nand_readDirect,
    .writeDirect = nand_writeDirect,

    .error = nand_error,
    .clearerr = nand_clearError,
};


bool nand_init(Nand *chip, struct Heap *heap, unsigned chip_select)
{
    if (!commonInit(chip, heap, chip_select))
        return false;

    chip->fd.priv.vt = &nand_buffered_vt;
    chip->fd.priv.flags |= KB_BUFFERED;

    chip->fd.priv.buf = heap_allocmem(heap, NAND_BLOCK_SIZE);
    if (!chip->fd.priv.buf)
    {
        LOG_ERR("nand: error allocating block buffer\n");
        return false;
    }

    // Load the first block in the cache
    return nand_readDirect(&chip->fd, 0, chip->fd.priv.buf, 0, chip->fd.blk_size);
}


bool nand_initUnbuffered(Nand *chip, struct Heap *heap, unsigned chip_select)
{
    if (!commonInit(chip, heap, chip_select))
        return false;

    chip->fd.priv.vt = &nand_unbuffered_vt;
    return true;
}