#include <linux/crc32.h>
#include <linux/slab.h>
#include "mtk_bmt.h"

#define nlog_err(ni, ...) printk(KERN_ERR __VA_ARGS__)
#define nlog_info(ni, ...) printk(KERN_INFO __VA_ARGS__)
#define nlog_debug(ni, ...) printk(KERN_INFO __VA_ARGS__)
#define nlog_warn(ni, ...) printk(KERN_WARNING __VA_ARGS__)

#define NMBM_MAGIC_SIGNATURE			0x304d4d4e	/* NMM0 */
#define NMBM_MAGIC_INFO_TABLE			0x314d4d4e	/* NMM1 */

#define NMBM_VERSION_MAJOR_S			0
#define NMBM_VERSION_MAJOR_M			0xffff
#define NMBM_VERSION_MINOR_S			16
#define NMBM_VERSION_MINOR_M			0xffff
#define NMBM_VERSION_MAKE(major, minor)		(((major) & NMBM_VERSION_MAJOR_M) | \
						(((minor) & NMBM_VERSION_MINOR_M) << \
						NMBM_VERSION_MINOR_S))
#define NMBM_VERSION_MAJOR_GET(ver)		(((ver) >> NMBM_VERSION_MAJOR_S) & \
						NMBM_VERSION_MAJOR_M)
#define NMBM_VERSION_MINOR_GET(ver)		(((ver) >> NMBM_VERSION_MINOR_S) & \
						NMBM_VERSION_MINOR_M)

#define NMBM_BITMAP_UNIT_SIZE			(sizeof(u32))
#define NMBM_BITMAP_BITS_PER_BLOCK		2
#define NMBM_BITMAP_BITS_PER_UNIT		(8 * sizeof(u32))
#define NMBM_BITMAP_BLOCKS_PER_UNIT		(NMBM_BITMAP_BITS_PER_UNIT / \
						 NMBM_BITMAP_BITS_PER_BLOCK)

#define NMBM_SPARE_BLOCK_MULTI			1
#define NMBM_SPARE_BLOCK_DIV			2
#define NMBM_SPARE_BLOCK_MIN			2

#define NMBM_MGMT_DIV				16
#define NMBM_MGMT_BLOCKS_MIN			32

#define NMBM_TRY_COUNT				3

#define BLOCK_ST_BAD				0
#define BLOCK_ST_NEED_REMAP			2
#define BLOCK_ST_GOOD				3
#define BLOCK_ST_MASK				3

#define NMBM_VER_MAJOR			1
#define NMBM_VER_MINOR			0
#define NMBM_VER			NMBM_VERSION_MAKE(NMBM_VER_MAJOR, \
							  NMBM_VER_MINOR)

struct nmbm_header {
	u32 magic;
	u32 version;
	u32 size;
	u32 checksum;
};

struct nmbm_signature {
	struct nmbm_header header;
	uint64_t nand_size;
	u32 block_size;
	u32 page_size;
	u32 spare_size;
	u32 mgmt_start_pb;
	u8 max_try_count;
	u8 padding[3];
};

struct nmbm_info_table_header {
	struct nmbm_header header;
	u32 write_count;
	u32 state_table_off;
	u32 mapping_table_off;
	u32 padding;
};

struct nmbm_instance {
	u32 rawpage_size;
	u32 rawblock_size;
	u32 rawchip_size;

	struct nmbm_signature signature;

	u8 *info_table_cache;
	u32 info_table_size;
	u32 info_table_spare_blocks;
	struct nmbm_info_table_header info_table;

	u32 *block_state;
	u32 block_state_changed;
	u32 state_table_size;

	int32_t *block_mapping;
	u32 block_mapping_changed;
	u32 mapping_table_size;

	u8 *page_cache;

	int protected;

	u32 block_count;
	u32 data_block_count;

	u32 mgmt_start_ba;
	u32 main_table_ba;
	u32 backup_table_ba;
	u32 mapping_blocks_ba;
	u32 mapping_blocks_top_ba;
	u32 signature_ba;

	u32 max_ratio;
	u32 max_reserved_blocks;
	bool empty_page_ecc_ok;
	bool force_create;
};

static inline u32 nmbm_crc32(u32 crcval, const void *buf, size_t size)
{
	unsigned int chksz;
	const unsigned char *p = buf;

	while (size) {
		if (size > UINT_MAX)
			chksz = UINT_MAX;
		else
			chksz = (uint)size;

		crcval = crc32_le(crcval, p, chksz);
		size -= chksz;
		p += chksz;
	}

	return crcval;
}
/*
 * nlog_table_creation - Print log of table creation event
 * @ni: NMBM instance structure
 * @main_table: whether the table is main info table
 * @start_ba: start block address of the table
 * @end_ba: block address after the end of the table
 */
static void nlog_table_creation(struct nmbm_instance *ni, bool main_table,
			       uint32_t start_ba, uint32_t end_ba)
{
	if (start_ba == end_ba - 1)
		nlog_info(ni, "%s info table has been written to block %u\n",
			 main_table ? "Main" : "Backup", start_ba);
	else
		nlog_info(ni, "%s info table has been written to block %u-%u\n",
			 main_table ? "Main" : "Backup", start_ba, end_ba - 1);
}

/*
 * nlog_table_update - Print log of table update event
 * @ni: NMBM instance structure
 * @main_table: whether the table is main info table
 * @start_ba: start block address of the table
 * @end_ba: block address after the end of the table
 */
static void nlog_table_update(struct nmbm_instance *ni, bool main_table,
			     uint32_t start_ba, uint32_t end_ba)
{
	if (start_ba == end_ba - 1)
		nlog_debug(ni, "%s info table has been updated in block %u\n",
			  main_table ? "Main" : "Backup", start_ba);
	else
		nlog_debug(ni, "%s info table has been updated in block %u-%u\n",
			  main_table ? "Main" : "Backup", start_ba, end_ba - 1);
}

/*
 * nlog_table_found - Print log of table found event
 * @ni: NMBM instance structure
 * @first_table: whether the table is first found info table
 * @write_count: write count of the info table
 * @start_ba: start block address of the table
 * @end_ba: block address after the end of the table
 */
static void nlog_table_found(struct nmbm_instance *ni, bool first_table,
			    uint32_t write_count, uint32_t start_ba,
			    uint32_t end_ba)
{
	if (start_ba == end_ba - 1)
		nlog_info(ni, "%s info table with writecount %u found in block %u\n",
			 first_table ? "First" : "Second", write_count,
			 start_ba);
	else
		nlog_info(ni, "%s info table with writecount %u found in block %u-%u\n",
			 first_table ? "First" : "Second", write_count,
			 start_ba, end_ba - 1);
}

/*****************************************************************************/
/* Address conversion functions */
/*****************************************************************************/

/*
 * ba2addr - Convert a block address to linear address
 * @ni: NMBM instance structure
 * @ba: Block address
 */
static uint64_t ba2addr(struct nmbm_instance *ni, uint32_t ba)
{
	return (uint64_t)ba << bmtd.blk_shift;
}
/*
 * size2blk - Get minimum required blocks for storing specific size of data
 * @ni: NMBM instance structure
 * @size: size for storing
 */
static uint32_t size2blk(struct nmbm_instance *ni, uint64_t size)
{
	return (size + bmtd.blk_size - 1) >> bmtd.blk_shift;
}

/*****************************************************************************/
/* High level NAND chip APIs */
/*****************************************************************************/

/*
 * nmbm_read_phys_page - Read page with retry
 * @ni: NMBM instance structure
 * @addr: linear address where the data will be read from
 * @data: the main data to be read
 * @oob: the oob data to be read
 *
 * Read a page for at most NMBM_TRY_COUNT times.
 *
 * Return 0 for success, positive value for corrected bitflip count,
 * -EBADMSG for ecc error, other negative values for other errors
 */
static int nmbm_read_phys_page(struct nmbm_instance *ni, uint64_t addr,
			       void *data, void *oob)
{
	int tries, ret;

	for (tries = 0; tries < NMBM_TRY_COUNT; tries++) {
		struct mtd_oob_ops ops = {
			.mode = MTD_OPS_PLACE_OOB,
			.oobbuf = oob,
			.datbuf = data,
		};

		if (data)
			ops.len = bmtd.pg_size;
		if (oob)
			ops.ooblen = mtd_oobavail(bmtd.mtd, &ops);

		ret = bmtd._read_oob(bmtd.mtd, addr, &ops);
		if (ret == -EUCLEAN)
			return min_t(u32, bmtd.mtd->bitflip_threshold + 1,
				     bmtd.mtd->ecc_strength);
		if (ret >= 0)
			return 0;
	}

	if (ret != -EBADMSG)
		nlog_err(ni, "Page read failed at address 0x%08llx\n", addr);

	return ret;
}

/*
 * nmbm_write_phys_page - Write page with retry
 * @ni: NMBM instance structure
 * @addr: linear address where the data will be written to
 * @data: the main data to be written
 * @oob: the oob data to be written
 *
 * Write a page for at most NMBM_TRY_COUNT times.
 */
static bool nmbm_write_phys_page(struct nmbm_instance *ni, uint64_t addr,
				 const void *data, const void *oob)
{
	int tries, ret;

	for (tries = 0; tries < NMBM_TRY_COUNT; tries++) {
		struct mtd_oob_ops ops = {
			.mode = MTD_OPS_PLACE_OOB,
			.oobbuf = (void *)oob,
			.datbuf = (void *)data,
		};

		if (data)
			ops.len = bmtd.pg_size;
		if (oob)
			ops.ooblen = mtd_oobavail(bmtd.mtd, &ops);

		ret = bmtd._write_oob(bmtd.mtd, addr, &ops);
		if (!ret)
			return true;
	}

	nlog_err(ni, "Page write failed at address 0x%08llx\n", addr);

	return false;
}

/*
 * nmbm_erase_phys_block - Erase a block with retry
 * @ni: NMBM instance structure
 * @addr: Linear address
 *
 * Erase a block for at most NMBM_TRY_COUNT times.
 */
static bool nmbm_erase_phys_block(struct nmbm_instance *ni, uint64_t addr)
{
	int tries, ret;

	for (tries = 0; tries < NMBM_TRY_COUNT; tries++) {
		struct erase_info ei = {
			.addr = addr,
			.len = bmtd.mtd->erasesize,
		};

		ret = bmtd._erase(bmtd.mtd, &ei);
		if (!ret)
			return true;
	}

	nlog_err(ni, "Block erasure failed at address 0x%08llx\n", addr);

	return false;
}

/*
 * nmbm_check_bad_phys_block - Check whether a block is marked bad in OOB
 * @ni: NMBM instance structure
 * @ba: block address
 */
static bool nmbm_check_bad_phys_block(struct nmbm_instance *ni, uint32_t ba)
{
	uint64_t addr = ba2addr(ni, ba);

	return bmtd._block_isbad(bmtd.mtd, addr);
}

/*
 * nmbm_mark_phys_bad_block - Mark a block bad
 * @ni: NMBM instance structure
 * @addr: Linear address
 */
static int nmbm_mark_phys_bad_block(struct nmbm_instance *ni, uint32_t ba)
{
	uint64_t addr = ba2addr(ni, ba);

	nlog_info(ni, "Block %u [0x%08llx] will be marked bad\n", ba, addr);

	return bmtd._block_markbad(bmtd.mtd, addr);
}

/*****************************************************************************/
/* NMBM related functions */
/*****************************************************************************/

/*
 * nmbm_check_header - Check whether a NMBM structure is valid
 * @data: pointer to a NMBM structure with a NMBM header at beginning
 * @size: Size of the buffer pointed by @header
 *
 * The size of the NMBM structure may be larger than NMBM header,
 * e.g. block mapping table and block state table.
 */
static bool nmbm_check_header(const void *data, uint32_t size)
{
	const struct nmbm_header *header = data;
	struct nmbm_header nhdr;
	uint32_t new_checksum;

	/*
	 * Make sure expected structure size is equal or smaller than
	 * buffer size.
	 */
	if (header->size > size)
		return false;

	memcpy(&nhdr, data, sizeof(nhdr));

	nhdr.checksum = 0;
	new_checksum = nmbm_crc32(0, &nhdr, sizeof(nhdr));
	if (header->size > sizeof(nhdr))
		new_checksum = nmbm_crc32(new_checksum,
			(const uint8_t *)data + sizeof(nhdr),
			header->size - sizeof(nhdr));

	if (header->checksum != new_checksum)
		return false;

	return true;
}

/*
 * nmbm_update_checksum - Update checksum of a NMBM structure
 * @header: pointer to a NMBM structure with a NMBM header at beginning
 *
 * The size of the NMBM structure must be specified by @header->size
 */
static void nmbm_update_checksum(struct nmbm_header *header)
{
	header->checksum = 0;
	header->checksum = nmbm_crc32(0, header, header->size);
}

/*
 * nmbm_get_spare_block_count - Calculate number of blocks should be reserved
 * @block_count: number of blocks of data
 *
 * Calculate number of blocks should be reserved for data
 */
static uint32_t nmbm_get_spare_block_count(uint32_t block_count)
{
	uint32_t val;

	val = (block_count + NMBM_SPARE_BLOCK_DIV / 2) / NMBM_SPARE_BLOCK_DIV;
	val *= NMBM_SPARE_BLOCK_MULTI;

	if (val < NMBM_SPARE_BLOCK_MIN)
		val = NMBM_SPARE_BLOCK_MIN;

	return val;
}

/*
 * nmbm_get_block_state_raw - Get state of a block from raw block state table
 * @block_state: pointer to raw block state table (bitmap)
 * @ba: block address
 */
static uint32_t nmbm_get_block_state_raw(u32 *block_state,
					 uint32_t ba)
{
	uint32_t unit, shift;

	unit = ba / NMBM_BITMAP_BLOCKS_PER_UNIT;
	shift = (ba % NMBM_BITMAP_BLOCKS_PER_UNIT) * NMBM_BITMAP_BITS_PER_BLOCK;

	return (block_state[unit] >> shift) & BLOCK_ST_MASK;
}

/*
 * nmbm_get_block_state - Get state of a block from block state table
 * @ni: NMBM instance structure
 * @ba: block address
 */
static uint32_t nmbm_get_block_state(struct nmbm_instance *ni, uint32_t ba)
{
	return nmbm_get_block_state_raw(ni->block_state, ba);
}

/*
 * nmbm_set_block_state - Set state of a block to block state table
 * @ni: NMBM instance structure
 * @ba: block address
 * @state: block state
 *
 * Set state of a block. If the block state changed, ni->block_state_changed
 * will be increased.
 */
static bool nmbm_set_block_state(struct nmbm_instance *ni, uint32_t ba,
				 uint32_t state)
{
	uint32_t unit, shift, orig;
	u32 uv;

	unit = ba / NMBM_BITMAP_BLOCKS_PER_UNIT;
	shift = (ba % NMBM_BITMAP_BLOCKS_PER_UNIT) * NMBM_BITMAP_BITS_PER_BLOCK;

	orig = (ni->block_state[unit] >> shift) & BLOCK_ST_MASK;
	state &= BLOCK_ST_MASK;

	uv = ni->block_state[unit] & (~(BLOCK_ST_MASK << shift));
	uv |= state << shift;
	ni->block_state[unit] = uv;

	if (orig != state) {
		ni->block_state_changed++;
		return true;
	}

	return false;
}

/*
 * nmbm_block_walk_asc - Skip specified number of good blocks, ascending addr.
 * @ni: NMBM instance structure
 * @ba: start physical block address
 * @nba: return physical block address after walk
 * @count: number of good blocks to be skipped
 * @limit: highest block address allowed for walking
 *
 * Start from @ba, skipping any bad blocks, counting @count good blocks, and
 * return the next good block address.
 *
 * If no enough good blocks counted while @limit reached, false will be returned.
 *
 * If @count == 0, nearest good block address will be returned.
 * @limit is not counted in walking.
 */
static bool nmbm_block_walk_asc(struct nmbm_instance *ni, uint32_t ba,
				uint32_t *nba, uint32_t count,
				uint32_t limit)
{
	int32_t nblock = count;

	if (limit >= ni->block_count)
		limit = ni->block_count - 1;

	while (ba < limit) {
		if (nmbm_get_block_state(ni, ba) == BLOCK_ST_GOOD)
			nblock--;

		if (nblock < 0) {
			*nba = ba;
			return true;
		}

		ba++;
	}

	return false;
}

/*
 * nmbm_block_walk_desc - Skip specified number of good blocks, descending addr
 * @ni: NMBM instance structure
 * @ba: start physical block address
 * @nba: return physical block address after walk
 * @count: number of good blocks to be skipped
 * @limit: lowest block address allowed for walking
 *
 * Start from @ba, skipping any bad blocks, counting @count good blocks, and
 * return the next good block address.
 *
 * If no enough good blocks counted while @limit reached, false will be returned.
 *
 * If @count == 0, nearest good block address will be returned.
 * @limit is not counted in walking.
 */
static bool nmbm_block_walk_desc(struct nmbm_instance *ni, uint32_t ba,
				 uint32_t *nba, uint32_t count, uint32_t limit)
{
	int32_t nblock = count;

	if (limit >= ni->block_count)
		limit = ni->block_count - 1;

	while (ba > limit) {
		if (nmbm_get_block_state(ni, ba) == BLOCK_ST_GOOD)
			nblock--;

		if (nblock < 0) {
			*nba = ba;
			return true;
		}

		ba--;
	}

	return false;
}

/*
 * nmbm_block_walk - Skip specified number of good blocks from curr. block addr
 * @ni: NMBM instance structure
 * @ascending: whether to walk ascending
 * @ba: start physical block address
 * @nba: return physical block address after walk
 * @count: number of good blocks to be skipped
 * @limit: highest/lowest block address allowed for walking
 *
 * Start from @ba, skipping any bad blocks, counting @count good blocks, and
 * return the next good block address.
 *
 * If no enough good blocks counted while @limit reached, false will be returned.
 *
 * If @count == 0, nearest good block address will be returned.
 * @limit can be set to negative if no limit required.
 * @limit is not counted in walking.
 */
static bool nmbm_block_walk(struct nmbm_instance *ni, bool ascending,
			    uint32_t ba, uint32_t *nba, int32_t count,
			    int32_t limit)
{
	if (ascending)
		return nmbm_block_walk_asc(ni, ba, nba, count, limit);

	return nmbm_block_walk_desc(ni, ba, nba, count, limit);
}

/*
 * nmbm_scan_badblocks - Scan and record all bad blocks
 * @ni: NMBM instance structure
 *
 * Scan the entire lower NAND chip and record all bad blocks in to block state
 * table.
 */
static void nmbm_scan_badblocks(struct nmbm_instance *ni)
{
	uint32_t ba;

	for (ba = 0; ba < ni->block_count; ba++) {
		if (nmbm_check_bad_phys_block(ni, ba)) {
			nmbm_set_block_state(ni, ba, BLOCK_ST_BAD);
			nlog_info(ni, "Bad block %u [0x%08llx]\n", ba,
				 ba2addr(ni, ba));
		}
	}
}

/*
 * nmbm_build_mapping_table - Build initial block mapping table
 * @ni: NMBM instance structure
 *
 * The initial mapping table will be compatible with the stratage of
 * factory production.
 */
static void nmbm_build_mapping_table(struct nmbm_instance *ni)
{
	uint32_t pb, lb;

	for (pb = 0, lb = 0; pb < ni->mgmt_start_ba; pb++) {
		if (nmbm_get_block_state(ni, pb) == BLOCK_ST_BAD)
			continue;

		/* Always map to the next good block */
		ni->block_mapping[lb++] = pb;
	}

	ni->data_block_count = lb;

	/* Unusable/Management blocks */
	for (pb = lb; pb < ni->block_count; pb++)
		ni->block_mapping[pb] = -1;
}

/*
 * nmbm_erase_block_and_check - Erase a block and check its usability
 * @ni: NMBM instance structure
 * @ba: block address to be erased
 *
 * Erase a block anc check its usability
 *
 * Return true if the block is usable, false if erasure failure or the block
 * has too many bitflips.
 */
static bool nmbm_erase_block_and_check(struct nmbm_instance *ni, uint32_t ba)
{
	uint64_t addr, off;
	bool success;
	int ret;

	success = nmbm_erase_phys_block(ni, ba2addr(ni, ba));
	if (!success)
		return false;

	if (!ni->empty_page_ecc_ok)
		return true;

	/* Check every page to make sure there aren't too many bitflips */

	addr = ba2addr(ni, ba);

	for (off = 0; off < bmtd.blk_size; off += bmtd.pg_size) {
		ret = nmbm_read_phys_page(ni, addr + off, ni->page_cache, NULL);
		if (ret == -EBADMSG) {
			/*
			 * empty_page_ecc_ok means the empty page is
			 * still protected by ECC. So reading pages with ECC
			 * enabled and -EBADMSG means there are too many
			 * bitflips that can't be recovered, and the block
			 * containing the page should be marked bad.
			 */
			nlog_err(ni,
				 "Too many bitflips in empty page at 0x%llx\n",
				 addr + off);
			return false;
		}
	}

	return true;
}

/*
 * nmbm_erase_range - Erase a range of blocks
 * @ni: NMBM instance structure
 * @ba: block address where the erasure will start
 * @limit: top block address allowed for erasure
 *
 * Erase blocks within the specific range. Newly-found bad blocks will be
 * marked.
 *
 * @limit is not counted into the allowed erasure address.
 */
static void nmbm_erase_range(struct nmbm_instance *ni, uint32_t ba,
			     uint32_t limit)
{
	bool success;

	while (ba < limit) {
		if (nmbm_get_block_state(ni, ba) != BLOCK_ST_GOOD)
			goto next_block;

		/* Insurance to detect unexpected bad block marked by user */
		if (nmbm_check_bad_phys_block(ni, ba)) {
			nmbm_set_block_state(ni, ba, BLOCK_ST_BAD);
			goto next_block;
		}

		success = nmbm_erase_block_and_check(ni, ba);
		if (success)
			goto next_block;

		nmbm_mark_phys_bad_block(ni, ba);
		nmbm_set_block_state(ni, ba, BLOCK_ST_BAD);

	next_block:
		ba++;
	}
}

/*
 * nmbm_write_repeated_data - Write critical data to a block with retry
 * @ni: NMBM instance structure
 * @ba: block address where the data will be written to
 * @data: the data to be written
 * @size: size of the data
 *
 * Write data to every page of the block. Success only if all pages within
 * this block have been successfully written.
 *
 * Make sure data size is not bigger than one page.
 *
 * This function will write and verify every page for at most
 * NMBM_TRY_COUNT times.
 */
static bool nmbm_write_repeated_data(struct nmbm_instance *ni, uint32_t ba,
				     const void *data, uint32_t size)
{
	uint64_t addr, off;
	bool success;
	int ret;

	if (size > bmtd.pg_size)
		return false;

	addr = ba2addr(ni, ba);

	for (off = 0; off < bmtd.blk_size; off += bmtd.pg_size) {
		/* Prepare page data. fill 0xff to unused region */
		memcpy(ni->page_cache, data, size);
		memset(ni->page_cache + size, 0xff, ni->rawpage_size - size);

		success = nmbm_write_phys_page(ni, addr + off, ni->page_cache, NULL);
		if (!success)
			return false;

		/* Verify the data just written. ECC error indicates failure */
		ret = nmbm_read_phys_page(ni, addr + off, ni->page_cache, NULL);
		if (ret < 0)
			return false;

		if (memcmp(ni->page_cache, data, size))
			return false;
	}

	return true;
}

/*
 * nmbm_write_signature - Write signature to NAND chip
 * @ni: NMBM instance structure
 * @limit: top block address allowed for writing
 * @signature: the signature to be written
 * @signature_ba: the actual block address where signature is written to
 *
 * Write signature within a specific range, from chip bottom to limit.
 * At most one block will be written.
 *
 * @limit is not counted into the allowed write address.
 */
static bool nmbm_write_signature(struct nmbm_instance *ni, uint32_t limit,
				 const struct nmbm_signature *signature,
				 uint32_t *signature_ba)
{
	uint32_t ba = ni->block_count - 1;
	bool success;

	while (ba > limit) {
		if (nmbm_get_block_state(ni, ba) != BLOCK_ST_GOOD)
			goto next_block;

		/* Insurance to detect unexpected bad block marked by user */
		if (nmbm_check_bad_phys_block(ni, ba)) {
			nmbm_set_block_state(ni, ba, BLOCK_ST_BAD);
			goto next_block;
		}

		success = nmbm_erase_block_and_check(ni, ba);
		if (!success)
			goto skip_bad_block;

		success = nmbm_write_repeated_data(ni, ba, signature,
						   sizeof(*signature));
		if (success) {
			*signature_ba = ba;
			return true;
		}

	skip_bad_block:
		nmbm_mark_phys_bad_block(ni, ba);
		nmbm_set_block_state(ni, ba, BLOCK_ST_BAD);

	next_block:
		ba--;
	};

	return false;
}

/*
 * nmbn_read_data - Read data
 * @ni: NMBM instance structure
 * @addr: linear address where the data will be read from
 * @data: the data to be read
 * @size: the size of data
 *
 * Read data range.
 * Every page will be tried for at most NMBM_TRY_COUNT times.
 *
 * Return 0 for success, positive value for corrected bitflip count,
 * -EBADMSG for ecc error, other negative values for other errors
 */
static int nmbn_read_data(struct nmbm_instance *ni, uint64_t addr, void *data,
			  uint32_t size)
{
	uint64_t off = addr;
	uint8_t *ptr = data;
	uint32_t sizeremain = size, chunksize, leading;
	int ret;

	while (sizeremain) {
		leading = off & (bmtd.pg_size - 1);
		chunksize = bmtd.pg_size - leading;
		if (chunksize > sizeremain)
			chunksize = sizeremain;

		if (chunksize == bmtd.pg_size) {
			ret = nmbm_read_phys_page(ni, off - leading, ptr, NULL);
			if (ret < 0)
				return ret;
		} else {
			ret = nmbm_read_phys_page(ni, off - leading,
						  ni->page_cache, NULL);
			if (ret < 0)
				return ret;

			memcpy(ptr, ni->page_cache + leading, chunksize);
		}

		off += chunksize;
		ptr += chunksize;
		sizeremain -= chunksize;
	}

	return 0;
}

/*
 * nmbn_write_verify_data - Write data with validation
 * @ni: NMBM instance structure
 * @addr: linear address where the data will be written to
 * @data: the data to be written
 * @size: the size of data
 *
 * Write data and verify.
 * Every page will be tried for at most NMBM_TRY_COUNT times.
 */
static bool nmbn_write_verify_data(struct nmbm_instance *ni, uint64_t addr,
				   const void *data, uint32_t size)
{
	uint64_t off = addr;
	const uint8_t *ptr = data;
	uint32_t sizeremain = size, chunksize, leading;
	bool success;
	int ret;

	while (sizeremain) {
		leading = off & (bmtd.pg_size - 1);
		chunksize = bmtd.pg_size - leading;
		if (chunksize > sizeremain)
			chunksize = sizeremain;

		/* Prepare page data. fill 0xff to unused region */
		memset(ni->page_cache, 0xff, ni->rawpage_size);
		memcpy(ni->page_cache + leading, ptr, chunksize);

		success = nmbm_write_phys_page(ni, off - leading,
					       ni->page_cache, NULL);
		if (!success)
			return false;

		/* Verify the data just written. ECC error indicates failure */
		ret = nmbm_read_phys_page(ni, off - leading, ni->page_cache, NULL);
		if (ret < 0)
			return false;

		if (memcmp(ni->page_cache + leading, ptr, chunksize))
			return false;

		off += chunksize;
		ptr += chunksize;
		sizeremain -= chunksize;
	}

	return true;
}

/*
 * nmbm_write_mgmt_range - Write management data into NAND within a range
 * @ni: NMBM instance structure
 * @addr: preferred start block address for writing
 * @limit: highest block address allowed for writing
 * @data: the data to be written
 * @size: the size of data
 * @actual_start_ba: actual start block address of data
 * @actual_end_ba: block address after the end of data
 *
 * @limit is not counted into the allowed write address.
 */
static bool nmbm_write_mgmt_range(struct nmbm_instance *ni, uint32_t ba,
				  uint32_t limit, const void *data,
				  uint32_t size, uint32_t *actual_start_ba,
				  uint32_t *actual_end_ba)
{
	const uint8_t *ptr = data;
	uint32_t sizeremain = size, chunksize;
	bool success;

	while (sizeremain && ba < limit) {
		chunksize = sizeremain;
		if (chunksize > bmtd.blk_size)
			chunksize = bmtd.blk_size;

		if (nmbm_get_block_state(ni, ba) != BLOCK_ST_GOOD)
			goto next_block;

		/* Insurance to detect unexpected bad block marked by user */
		if (nmbm_check_bad_phys_block(ni, ba)) {
			nmbm_set_block_state(ni, ba, BLOCK_ST_BAD);
			goto next_block;
		}

		success = nmbm_erase_block_and_check(ni, ba);
		if (!success)
			goto skip_bad_block;

		success = nmbn_write_verify_data(ni, ba2addr(ni, ba), ptr,
						 chunksize);
		if (!success)
			goto skip_bad_block;

		if (sizeremain == size)
			*actual_start_ba = ba;

		ptr += chunksize;
		sizeremain -= chunksize;

		goto next_block;

	skip_bad_block:
		nmbm_mark_phys_bad_block(ni, ba);
		nmbm_set_block_state(ni, ba, BLOCK_ST_BAD);

	next_block:
		ba++;
	}

	if (sizeremain)
		return false;

	*actual_end_ba = ba;

	return true;
}

/*
 * nmbm_generate_info_table_cache - Generate info table cache data
 * @ni: NMBM instance structure
 *
 * Generate info table cache data to be written into flash.
 */
static bool nmbm_generate_info_table_cache(struct nmbm_instance *ni)
{
	bool changed = false;

	memset(ni->info_table_cache, 0xff, ni->info_table_size);

	memcpy(ni->info_table_cache + ni->info_table.state_table_off,
	       ni->block_state, ni->state_table_size);

	memcpy(ni->info_table_cache + ni->info_table.mapping_table_off,
		ni->block_mapping, ni->mapping_table_size);

	ni->info_table.header.magic = NMBM_MAGIC_INFO_TABLE;
	ni->info_table.header.version = NMBM_VER;
	ni->info_table.header.size = ni->info_table_size;

	if (ni->block_state_changed || ni->block_mapping_changed) {
		ni->info_table.write_count++;
		changed = true;
	}

	memcpy(ni->info_table_cache, &ni->info_table, sizeof(ni->info_table));

	nmbm_update_checksum((struct nmbm_header *)ni->info_table_cache);

	return changed;
}

/*
 * nmbm_write_info_table - Write info table into NAND within a range
 * @ni: NMBM instance structure
 * @ba: preferred start block address for writing
 * @limit: highest block address allowed for writing
 * @actual_start_ba: actual start block address of info table
 * @actual_end_ba: block address after the end of info table
 *
 * @limit is counted into the allowed write address.
 */
static bool nmbm_write_info_table(struct nmbm_instance *ni, uint32_t ba,
				  uint32_t limit, uint32_t *actual_start_ba,
				  uint32_t *actual_end_ba)
{
	return nmbm_write_mgmt_range(ni, ba, limit, ni->info_table_cache,
				     ni->info_table_size, actual_start_ba,
				     actual_end_ba);
}

/*
 * nmbm_mark_tables_clean - Mark info table `clean'
 * @ni: NMBM instance structure
 */
static void nmbm_mark_tables_clean(struct nmbm_instance *ni)
{
	ni->block_state_changed = 0;
	ni->block_mapping_changed = 0;
}

/*
 * nmbm_try_reserve_blocks - Reserve blocks with compromisation
 * @ni: NMBM instance structure
 * @ba: start physical block address
 * @nba: return physical block address after reservation
 * @count: number of good blocks to be skipped
 * @min_count: minimum number of good blocks to be skipped
 * @limit: highest/lowest block address allowed for walking
 *
 * Reserve specific blocks. If failed, try to reserve as many as possible.
 */
static bool nmbm_try_reserve_blocks(struct nmbm_instance *ni, uint32_t ba,
				    uint32_t *nba, uint32_t count,
				    int32_t min_count, int32_t limit)
{
	int32_t nblocks = count;
	bool success;

	while (nblocks >= min_count) {
		success = nmbm_block_walk(ni, true, ba, nba, nblocks, limit);
		if (success)
			return true;

		nblocks--;
	}

	return false;
}

/*
 * nmbm_rebuild_info_table - Build main & backup info table from scratch
 * @ni: NMBM instance structure
 * @allow_no_gap: allow no spare blocks between two tables
 */
static bool nmbm_rebuild_info_table(struct nmbm_instance *ni)
{
	uint32_t table_start_ba, table_end_ba, next_start_ba;
	uint32_t main_table_end_ba;
	bool success;

	/* Set initial value */
	ni->main_table_ba = 0;
	ni->backup_table_ba = 0;
	ni->mapping_blocks_ba = ni->mapping_blocks_top_ba;

	/* Write main table */
	success = nmbm_write_info_table(ni, ni->mgmt_start_ba,
					ni->mapping_blocks_top_ba,
					&table_start_ba, &table_end_ba);
	if (!success) {
		/* Failed to write main table, data will be lost */
		nlog_err(ni, "Unable to write at least one info table!\n");
		nlog_err(ni, "Please save your data before power off!\n");
		ni->protected = 1;
		return false;
	}

	/* Main info table is successfully written, record its offset */
	ni->main_table_ba = table_start_ba;
	main_table_end_ba = table_end_ba;

	/* Adjust mapping_blocks_ba */
	ni->mapping_blocks_ba = table_end_ba;

	nmbm_mark_tables_clean(ni);

	nlog_table_creation(ni, true, table_start_ba, table_end_ba);

	/* Reserve spare blocks for main info table. */
	success = nmbm_try_reserve_blocks(ni, table_end_ba,
					  &next_start_ba,
					  ni->info_table_spare_blocks, 0,
					  ni->mapping_blocks_top_ba -
					  size2blk(ni, ni->info_table_size));
	if (!success) {
		/* There is no spare block. */
		nlog_debug(ni, "No room for backup info table\n");
		return true;
	}

	/* Write backup info table. */
	success = nmbm_write_info_table(ni, next_start_ba,
					ni->mapping_blocks_top_ba,
					&table_start_ba, &table_end_ba);
	if (!success) {
		/* There is no enough blocks for backup table. */
		nlog_debug(ni, "No room for backup info table\n");
		return true;
	}

	/* Backup table is successfully written, record its offset */
	ni->backup_table_ba = table_start_ba;

	/* Adjust mapping_blocks_off */
	ni->mapping_blocks_ba = table_end_ba;

	/* Erase spare blocks of main table to clean possible interference data */
	nmbm_erase_range(ni, main_table_end_ba, ni->backup_table_ba);

	nlog_table_creation(ni, false, table_start_ba, table_end_ba);

	return true;
}

/*
 * nmbm_rescue_single_info_table - Rescue when there is only one info table
 * @ni: NMBM instance structure
 *
 * This function is called when there is only one info table exists.
 * This function may fail if we can't write new info table
 */
static bool nmbm_rescue_single_info_table(struct nmbm_instance *ni)
{
	uint32_t table_start_ba, table_end_ba, write_ba;
	bool success;

	/* Try to write new info table in front of existing table */
	success = nmbm_write_info_table(ni, ni->mgmt_start_ba,
					ni->main_table_ba,
					&table_start_ba,
					&table_end_ba);
	if (success) {
		/*
		 * New table becomes the main table, existing table becomes
		 * the backup table.
		 */
		ni->backup_table_ba = ni->main_table_ba;
		ni->main_table_ba = table_start_ba;

		nmbm_mark_tables_clean(ni);

		/* Erase spare blocks of main table to clean possible interference data */
		nmbm_erase_range(ni, table_end_ba, ni->backup_table_ba);

		nlog_table_creation(ni, true, table_start_ba, table_end_ba);

		return true;
	}

	/* Try to reserve spare blocks for existing table */
	success = nmbm_try_reserve_blocks(ni, ni->mapping_blocks_ba, &write_ba,
					  ni->info_table_spare_blocks, 0,
					  ni->mapping_blocks_top_ba -
					  size2blk(ni, ni->info_table_size));
	if (!success) {
		nlog_warn(ni, "Failed to rescue single info table\n");
		return false;
	}

	/* Try to write new info table next to the existing table */
	while (write_ba >= ni->mapping_blocks_ba) {
		success = nmbm_write_info_table(ni, write_ba,
						ni->mapping_blocks_top_ba,
						&table_start_ba,
						&table_end_ba);
		if (success)
			break;

		write_ba--;
	}

	if (success) {
		/* Erase spare blocks of main table to clean possible interference data */
		nmbm_erase_range(ni, ni->mapping_blocks_ba, table_start_ba);

		/* New table becomes the backup table */
		ni->backup_table_ba = table_start_ba;
		ni->mapping_blocks_ba = table_end_ba;

		nmbm_mark_tables_clean(ni);

		nlog_table_creation(ni, false, table_start_ba, table_end_ba);

		return true;
	}

	nlog_warn(ni, "Failed to rescue single info table\n");
	return false;
}

/*
 * nmbm_update_single_info_table - Update specific one info table
 * @ni: NMBM instance structure
 */
static bool nmbm_update_single_info_table(struct nmbm_instance *ni,
					  bool update_main_table)
{
	uint32_t write_start_ba, write_limit, table_start_ba, table_end_ba;
	bool success;

	/* Determine the write range */
	if (update_main_table) {
		write_start_ba = ni->main_table_ba;
		write_limit = ni->backup_table_ba;
	} else {
		write_start_ba = ni->backup_table_ba;
		write_limit = ni->mapping_blocks_top_ba;
	}

	success = nmbm_write_info_table(ni, write_start_ba, write_limit,
					&table_start_ba, &table_end_ba);
	if (success) {
		if (update_main_table) {
			ni->main_table_ba = table_start_ba;
		} else {
			ni->backup_table_ba = table_start_ba;
			ni->mapping_blocks_ba = table_end_ba;
		}

		nmbm_mark_tables_clean(ni);

		nlog_table_update(ni, update_main_table, table_start_ba,
				 table_end_ba);

		return true;
	}

	if (update_main_table) {
		/*
		 * If failed to update main table, make backup table the new
		 * main table, and call nmbm_rescue_single_info_table()
		 */
		nlog_warn(ni, "Unable to update %s info table\n",
			 update_main_table ? "Main" : "Backup");

		ni->main_table_ba = ni->backup_table_ba;
		ni->backup_table_ba = 0;
		return nmbm_rescue_single_info_table(ni);
	}

	/* Only one table left */
	ni->mapping_blocks_ba = ni->backup_table_ba;
	ni->backup_table_ba = 0;

	return false;
}

/*
 * nmbm_rescue_main_info_table - Rescue when failed to write main info table
 * @ni: NMBM instance structure
 *
 * This function is called when main info table failed to be written, and
 *    backup info table exists.
 */
static bool nmbm_rescue_main_info_table(struct nmbm_instance *ni)
{
	uint32_t tmp_table_start_ba, tmp_table_end_ba, main_table_start_ba;
	uint32_t main_table_end_ba, write_ba;
	uint32_t info_table_erasesize = size2blk(ni, ni->info_table_size);
	bool success;

	/* Try to reserve spare blocks for existing backup info table */
	success = nmbm_try_reserve_blocks(ni, ni->mapping_blocks_ba, &write_ba,
					  ni->info_table_spare_blocks, 0,
					  ni->mapping_blocks_top_ba -
					  info_table_erasesize);
	if (!success) {
		/* There is no spare block. Backup info table becomes the main table. */
		nlog_err(ni, "No room for temporary info table\n");
		ni->main_table_ba = ni->backup_table_ba;
		ni->backup_table_ba = 0;
		return true;
	}

	/* Try to write temporary info table into spare unmapped blocks */
	while (write_ba >= ni->mapping_blocks_ba) {
		success = nmbm_write_info_table(ni, write_ba,
						ni->mapping_blocks_top_ba,
						&tmp_table_start_ba,
						&tmp_table_end_ba);
		if (success)
			break;

		write_ba--;
	}

	if (!success) {
		/* Backup info table becomes the main table */
		nlog_err(ni, "Failed to update main info table\n");
		ni->main_table_ba = ni->backup_table_ba;
		ni->backup_table_ba = 0;
		return true;
	}

	/* Adjust mapping_blocks_off */
	ni->mapping_blocks_ba = tmp_table_end_ba;

	/*
	 * Now write main info table at the beginning of management area.
	 * This operation will generally destroy the original backup info
	 * table.
	 */
	success = nmbm_write_info_table(ni, ni->mgmt_start_ba,
					tmp_table_start_ba,
					&main_table_start_ba,
					&main_table_end_ba);
	if (!success) {
		/* Temporary info table becomes the main table */
		ni->main_table_ba = tmp_table_start_ba;
		ni->backup_table_ba = 0;

		nmbm_mark_tables_clean(ni);

		nlog_err(ni, "Failed to update main info table\n");

		return true;
	}

	/* Main info table has been successfully written, record its offset */
	ni->main_table_ba = main_table_start_ba;

	nmbm_mark_tables_clean(ni);

	nlog_table_creation(ni, true, main_table_start_ba, main_table_end_ba);

	/*
	 * Temporary info table becomes the new backup info table if it's
	 * not overwritten.
	 */
	if (main_table_end_ba <= tmp_table_start_ba) {
		ni->backup_table_ba = tmp_table_start_ba;

		nlog_table_creation(ni, false, tmp_table_start_ba,
				   tmp_table_end_ba);

		return true;
	}

	/* Adjust mapping_blocks_off */
	ni->mapping_blocks_ba = main_table_end_ba;

	/* Try to reserve spare blocks for new main info table */
	success = nmbm_try_reserve_blocks(ni, main_table_end_ba, &write_ba,
					  ni->info_table_spare_blocks, 0,
					  ni->mapping_blocks_top_ba -
					  info_table_erasesize);
	if (!success) {
		/* There is no spare block. Only main table exists. */
		nlog_err(ni, "No room for backup info table\n");
		ni->backup_table_ba = 0;
		return true;
	}

	/* Write new backup info table. */
	while (write_ba >= main_table_end_ba) {
		success = nmbm_write_info_table(ni, write_ba,
						ni->mapping_blocks_top_ba,
						&tmp_table_start_ba,
						&tmp_table_end_ba);
		if (success)
			break;

		write_ba--;
	}

	if (!success) {
		nlog_err(ni, "No room for backup info table\n");
		ni->backup_table_ba = 0;
		return true;
	}

	/* Backup info table has been successfully written, record its offset */
	ni->backup_table_ba = tmp_table_start_ba;

	/* Adjust mapping_blocks_off */
	ni->mapping_blocks_ba = tmp_table_end_ba;

	/* Erase spare blocks of main table to clean possible interference data */
	nmbm_erase_range(ni, main_table_end_ba, ni->backup_table_ba);

	nlog_table_creation(ni, false, tmp_table_start_ba, tmp_table_end_ba);

	return true;
}

/*
 * nmbm_update_info_table_once - Update info table once
 * @ni: NMBM instance structure
 * @force: force update
 *
 * Update both main and backup info table. Return true if at least one info
 * table has been successfully written.
 * This function only try to update info table once regard less of the result.
 */
static bool nmbm_update_info_table_once(struct nmbm_instance *ni, bool force)
{
	uint32_t table_start_ba, table_end_ba;
	uint32_t main_table_limit;
	bool success;

	/* Do nothing if there is no change */
	if (!nmbm_generate_info_table_cache(ni) && !force)
		return true;

	/* Check whether both two tables exist */
	if (!ni->backup_table_ba) {
		main_table_limit = ni->mapping_blocks_top_ba;
		goto write_main_table;
	}

	/*
	 * Write backup info table in its current range.
	 * Note that limit is set to mapping_blocks_top_off to provide as many
	 * spare blocks as possible for the backup table. If at last
	 * unmapped blocks are used by backup table, mapping_blocks_off will
	 * be adjusted.
	 */
	success = nmbm_write_info_table(ni, ni->backup_table_ba,
					ni->mapping_blocks_top_ba,
					&table_start_ba, &table_end_ba);
	if (!success) {
		/*
		 * There is nothing to do if failed to write backup table.
		 * Write the main table now.
		 */
		nlog_err(ni, "No room for backup table\n");
		ni->mapping_blocks_ba = ni->backup_table_ba;
		ni->backup_table_ba = 0;
		main_table_limit = ni->mapping_blocks_top_ba;
		goto write_main_table;
	}

	/* Backup table is successfully written, record its offset */
	ni->backup_table_ba = table_start_ba;

	/* Adjust mapping_blocks_off */
	ni->mapping_blocks_ba = table_end_ba;

	nmbm_mark_tables_clean(ni);

	/* The normal limit of main table */
	main_table_limit = ni->backup_table_ba;

	nlog_table_update(ni, false, table_start_ba, table_end_ba);

write_main_table:
	if (!ni->main_table_ba)
		goto rebuild_tables;

	/* Write main info table in its current range */
	success = nmbm_write_info_table(ni, ni->main_table_ba,
					main_table_limit, &table_start_ba,
					&table_end_ba);
	if (!success) {
		/* If failed to write main table, go rescue procedure */
		if (!ni->backup_table_ba)
			goto rebuild_tables;

		return nmbm_rescue_main_info_table(ni);
	}

	/* Main info table is successfully written, record its offset */
	ni->main_table_ba = table_start_ba;

	/* Adjust mapping_blocks_off */
	if (!ni->backup_table_ba)
		ni->mapping_blocks_ba = table_end_ba;

	nmbm_mark_tables_clean(ni);

	nlog_table_update(ni, true, table_start_ba, table_end_ba);

	return true;

rebuild_tables:
	return nmbm_rebuild_info_table(ni);
}

/*
 * nmbm_update_info_table - Update info table
 * @ni: NMBM instance structure
 *
 * Update both main and backup info table. Return true if at least one table
 * has been successfully written.
 * This function will try to update info table repeatedly until no new bad
 * block found during updating.
 */
static bool nmbm_update_info_table(struct nmbm_instance *ni)
{
	bool success;

	if (ni->protected)
		return true;

	while (ni->block_state_changed || ni->block_mapping_changed) {
		success = nmbm_update_info_table_once(ni, false);
		if (!success) {
			nlog_err(ni, "Failed to update info table\n");
			return false;
		}
	}

	return true;
}

/*
 * nmbm_map_block - Map a bad block to a unused spare block
 * @ni: NMBM instance structure
 * @lb: logic block addr to map
 */
static bool nmbm_map_block(struct nmbm_instance *ni, uint32_t lb)
{
	uint32_t pb;
	bool success;

	if (ni->mapping_blocks_ba == ni->mapping_blocks_top_ba) {
		nlog_warn(ni, "No spare unmapped blocks.\n");
		return false;
	}

	success = nmbm_block_walk(ni, false, ni->mapping_blocks_top_ba, &pb, 0,
				  ni->mapping_blocks_ba);
	if (!success) {
		nlog_warn(ni, "No spare unmapped blocks.\n");
		nmbm_update_info_table(ni);
		ni->mapping_blocks_top_ba = ni->mapping_blocks_ba;
		return false;
	}

	ni->block_mapping[lb] = pb;
	ni->mapping_blocks_top_ba--;
	ni->block_mapping_changed++;

	nlog_info(ni, "Logic block %u mapped to physical block %u\n", lb, pb);

	return true;
}

/*
 * nmbm_create_info_table - Create info table(s)
 * @ni: NMBM instance structure
 *
 * This function assumes that the chip has no existing info table(s)
 */
static bool nmbm_create_info_table(struct nmbm_instance *ni)
{
	uint32_t lb;
	bool success;

	/* Set initial mapping_blocks_top_off  */
	success = nmbm_block_walk(ni, false, ni->signature_ba,
				  &ni->mapping_blocks_top_ba, 1,
				  ni->mgmt_start_ba);
	if (!success) {
		nlog_err(ni, "No room for spare blocks\n");
		return false;
	}

	/* Generate info table cache */
	nmbm_generate_info_table_cache(ni);

	/* Write info table */
	success = nmbm_rebuild_info_table(ni);
	if (!success) {
		nlog_err(ni, "Failed to build info tables\n");
		return false;
	}

	/* Remap bad block(s) at end of data area */
	for (lb = ni->data_block_count; lb < ni->mgmt_start_ba; lb++) {
		success = nmbm_map_block(ni, lb);
		if (!success)
			break;

		ni->data_block_count++;
	}

	/* If state table and/or mapping table changed, update info table. */
	success = nmbm_update_info_table(ni);
	if (!success)
		return false;

	return true;
}

/*
 * nmbm_create_new - Create NMBM on a new chip
 * @ni: NMBM instance structure
 */
static bool nmbm_create_new(struct nmbm_instance *ni)
{
	bool success;

	/* Determine the boundary of management blocks */
	ni->mgmt_start_ba = ni->block_count * (NMBM_MGMT_DIV - ni->max_ratio) / NMBM_MGMT_DIV;

	if (ni->max_reserved_blocks && ni->block_count - ni->mgmt_start_ba > ni->max_reserved_blocks)
		ni->mgmt_start_ba = ni->block_count - ni->max_reserved_blocks;

	nlog_info(ni, "NMBM management region starts at block %u [0x%08llx]\n",
		  ni->mgmt_start_ba, ba2addr(ni, ni->mgmt_start_ba));

	/* Fill block state table & mapping table */
	nmbm_scan_badblocks(ni);
	nmbm_build_mapping_table(ni);

	/* Write signature */
	ni->signature.header.magic = NMBM_MAGIC_SIGNATURE;
	ni->signature.header.version = NMBM_VER;
	ni->signature.header.size = sizeof(ni->signature);
	ni->signature.nand_size = bmtd.total_blks << bmtd.blk_shift;
	ni->signature.block_size = bmtd.blk_size;
	ni->signature.page_size = bmtd.pg_size;
	ni->signature.spare_size = bmtd.mtd->oobsize;
	ni->signature.mgmt_start_pb = ni->mgmt_start_ba;
	ni->signature.max_try_count = NMBM_TRY_COUNT;
	nmbm_update_checksum(&ni->signature.header);

	success = nmbm_write_signature(ni, ni->mgmt_start_ba,
				       &ni->signature, &ni->signature_ba);
	if (!success) {
		nlog_err(ni, "Failed to write signature to a proper offset\n");
		return false;
	}

	nlog_info(ni, "Signature has been written to block %u [0x%08llx]\n",
		 ni->signature_ba, ba2addr(ni, ni->signature_ba));

	/* Write info table(s) */
	success = nmbm_create_info_table(ni);
	if (success) {
		nlog_info(ni, "NMBM has been successfully created\n");
		return true;
	}

	return false;
}

/*
 * nmbm_check_info_table_header - Check if a info table header is valid
 * @ni: NMBM instance structure
 * @data: pointer to the info table header
 */
static bool nmbm_check_info_table_header(struct nmbm_instance *ni, void *data)
{
	struct nmbm_info_table_header *ifthdr = data;

	if (ifthdr->header.magic != NMBM_MAGIC_INFO_TABLE)
		return false;

	if (ifthdr->header.size != ni->info_table_size)
		return false;

	if (ifthdr->mapping_table_off - ifthdr->state_table_off < ni->state_table_size)
		return false;

	if (ni->info_table_size - ifthdr->mapping_table_off < ni->mapping_table_size)
		return false;

	return true;
}

/*
 * nmbm_check_info_table - Check if a whole info table is valid
 * @ni: NMBM instance structure
 * @start_ba: start block address of this table
 * @end_ba: end block address of this table
 * @data: pointer to the info table header
 * @mapping_blocks_top_ba: return the block address of top remapped block
 */
static bool nmbm_check_info_table(struct nmbm_instance *ni, uint32_t start_ba,
				  uint32_t end_ba, void *data,
				  uint32_t *mapping_blocks_top_ba)
{
	struct nmbm_info_table_header *ifthdr = data;
	int32_t *block_mapping = (int32_t *)((uintptr_t)data + ifthdr->mapping_table_off);
	u32 *block_state = (u32 *)((uintptr_t)data + ifthdr->state_table_off);
	uint32_t minimum_mapping_pb = ni->signature_ba;
	uint32_t ba;

	for (ba = 0; ba < ni->data_block_count; ba++) {
		if ((block_mapping[ba] >= ni->data_block_count && block_mapping[ba] < end_ba) ||
		    block_mapping[ba] == ni->signature_ba)
			return false;

		if (block_mapping[ba] >= end_ba && block_mapping[ba] < minimum_mapping_pb)
			minimum_mapping_pb = block_mapping[ba];
	}

	for (ba = start_ba; ba < end_ba; ba++) {
		if (nmbm_get_block_state(ni, ba) != BLOCK_ST_GOOD)
			continue;

		if (nmbm_get_block_state_raw(block_state, ba) != BLOCK_ST_GOOD)
			return false;
	}

	*mapping_blocks_top_ba = minimum_mapping_pb - 1;

	return true;
}

/*
 * nmbm_try_load_info_table - Try to load info table from a address
 * @ni: NMBM instance structure
 * @ba: start block address of the info table
 * @eba: return the block address after end of the table
 * @write_count: return the write count of this table
 * @mapping_blocks_top_ba: return the block address of top remapped block
 * @table_loaded: used to record whether ni->info_table has valid data
 */
static bool nmbm_try_load_info_table(struct nmbm_instance *ni, uint32_t ba,
				     uint32_t *eba, uint32_t *write_count,
				     uint32_t *mapping_blocks_top_ba,
				     bool table_loaded)
{
	struct nmbm_info_table_header *ifthdr = (void *)ni->info_table_cache;
	uint8_t *off = ni->info_table_cache;
	uint32_t limit = ba + size2blk(ni, ni->info_table_size);
	uint32_t start_ba = 0, chunksize, sizeremain = ni->info_table_size;
	bool success, checkhdr = true;
	int ret;

	while (sizeremain && ba < limit) {
		if (nmbm_get_block_state(ni, ba) != BLOCK_ST_GOOD)
			goto next_block;

		if (nmbm_check_bad_phys_block(ni, ba)) {
			nmbm_set_block_state(ni, ba, BLOCK_ST_BAD);
			goto next_block;
		}

		chunksize = sizeremain;
		if (chunksize > bmtd.blk_size)
			chunksize = bmtd.blk_size;

		/* Assume block with ECC error has no info table data */
		ret = nmbn_read_data(ni, ba2addr(ni, ba), off, chunksize);
		if (ret < 0)
			goto skip_bad_block;
		else if (ret > 0)
			return false;

		if (checkhdr) {
			success = nmbm_check_info_table_header(ni, off);
			if (!success)
				return false;

			start_ba = ba;
			checkhdr = false;
		}

		off += chunksize;
		sizeremain -= chunksize;

		goto next_block;

	skip_bad_block:
		/* Only mark bad in memory */
		nmbm_set_block_state(ni, ba, BLOCK_ST_BAD);

	next_block:
		ba++;
	}

	if (sizeremain)
		return false;

	success = nmbm_check_header(ni->info_table_cache, ni->info_table_size);
	if (!success)
		return false;

	*eba = ba;
	*write_count = ifthdr->write_count;

	success = nmbm_check_info_table(ni, start_ba, ba, ni->info_table_cache,
					mapping_blocks_top_ba);
	if (!success)
		return false;

	if (!table_loaded || ifthdr->write_count > ni->info_table.write_count) {
		memcpy(&ni->info_table, ifthdr, sizeof(ni->info_table));
		memcpy(ni->block_state,
		       (uint8_t *)ifthdr + ifthdr->state_table_off,
		       ni->state_table_size);
		memcpy(ni->block_mapping,
		       (uint8_t *)ifthdr + ifthdr->mapping_table_off,
		       ni->mapping_table_size);
		ni->info_table.write_count = ifthdr->write_count;
	}

	return true;
}

/*
 * nmbm_search_info_table - Search info table from specific address
 * @ni: NMBM instance structure
 * @ba: start block address to search
 * @limit: highest block address allowed for searching
 * @table_start_ba: return the start block address of this table
 * @table_end_ba: return the block address after end of this table
 * @write_count: return the write count of this table
 * @mapping_blocks_top_ba: return the block address of top remapped block
 * @table_loaded: used to record whether ni->info_table has valid data
 */
static bool nmbm_search_info_table(struct nmbm_instance *ni, uint32_t ba,
				   uint32_t limit, uint32_t *table_start_ba,
				   uint32_t *table_end_ba,
				   uint32_t *write_count,
				   uint32_t *mapping_blocks_top_ba,
				   bool table_loaded)
{
	bool success;

	while (ba < limit - size2blk(ni, ni->info_table_size)) {
		success = nmbm_try_load_info_table(ni, ba, table_end_ba,
						   write_count,
						   mapping_blocks_top_ba,
						   table_loaded);
		if (success) {
			*table_start_ba = ba;
			return true;
		}

		ba++;
	}

	return false;
}

/*
 * nmbm_load_info_table - Load info table(s) from a chip
 * @ni: NMBM instance structure
 * @ba: start block address to search info table
 * @limit: highest block address allowed for searching
 */
static bool nmbm_load_info_table(struct nmbm_instance *ni, uint32_t ba,
				 uint32_t limit)
{
	uint32_t main_table_end_ba, backup_table_end_ba, table_end_ba;
	uint32_t main_mapping_blocks_top_ba, backup_mapping_blocks_top_ba;
	uint32_t main_table_write_count, backup_table_write_count;
	uint32_t i;
	bool success;

	/* Set initial value */
	ni->main_table_ba = 0;
	ni->backup_table_ba = 0;
	ni->info_table.write_count = 0;
	ni->mapping_blocks_top_ba = ni->signature_ba - 1;
	ni->data_block_count = ni->signature.mgmt_start_pb;

	/* Find first info table */
	success = nmbm_search_info_table(ni, ba, limit, &ni->main_table_ba,
		&main_table_end_ba, &main_table_write_count,
		&main_mapping_blocks_top_ba, false);
	if (!success) {
		nlog_warn(ni, "No valid info table found\n");
		return false;
	}

	table_end_ba = main_table_end_ba;

	nlog_table_found(ni, true, main_table_write_count, ni->main_table_ba,
			main_table_end_ba);

	/* Find second info table */
	success = nmbm_search_info_table(ni, main_table_end_ba, limit,
		&ni->backup_table_ba, &backup_table_end_ba,
		&backup_table_write_count, &backup_mapping_blocks_top_ba, true);
	if (!success) {
		nlog_warn(ni, "Second info table not found\n");
	} else {
		table_end_ba = backup_table_end_ba;

		nlog_table_found(ni, false, backup_table_write_count,
				ni->backup_table_ba, backup_table_end_ba);
	}

	/* Pick mapping_blocks_top_ba */
	if (!ni->backup_table_ba) {
		ni->mapping_blocks_top_ba= main_mapping_blocks_top_ba;
	} else {
		if (main_table_write_count >= backup_table_write_count)
			ni->mapping_blocks_top_ba = main_mapping_blocks_top_ba;
		else
			ni->mapping_blocks_top_ba = backup_mapping_blocks_top_ba;
	}

	/* Set final mapping_blocks_ba */
	ni->mapping_blocks_ba = table_end_ba;

	/* Set final data_block_count */
	for (i = ni->signature.mgmt_start_pb; i > 0; i--) {
		if (ni->block_mapping[i - 1] >= 0) {
			ni->data_block_count = i;
			break;
		}
	}

	/* Regenerate the info table cache from the final selected info table */
	nmbm_generate_info_table_cache(ni);

	/*
	 * If only one table exists, try to write another table.
	 * If two tables have different write count, try to update info table
	 */
	if (!ni->backup_table_ba) {
		success = nmbm_rescue_single_info_table(ni);
	} else if (main_table_write_count != backup_table_write_count) {
		/* Mark state & mapping tables changed */
		ni->block_state_changed = 1;
		ni->block_mapping_changed = 1;

		success = nmbm_update_single_info_table(ni,
			main_table_write_count < backup_table_write_count);
	} else {
		success = true;
	}

	/*
	 * If there is no spare unmapped blocks, or still only one table
	 * exists, set the chip to read-only
	 */
	if (ni->mapping_blocks_ba == ni->mapping_blocks_top_ba) {
		nlog_warn(ni, "No spare unmapped blocks. Device is now read-only\n");
		ni->protected = 1;
	} else if (!success) {
		nlog_warn(ni, "Only one info table found. Device is now read-only\n");
		ni->protected = 1;
	}

	return true;
}

/*
 * nmbm_load_existing - Load NMBM from a new chip
 * @ni: NMBM instance structure
 */
static bool nmbm_load_existing(struct nmbm_instance *ni)
{
	bool success;

	/* Calculate the boundary of management blocks */
	ni->mgmt_start_ba = ni->signature.mgmt_start_pb;

	nlog_debug(ni, "NMBM management region starts at block %u [0x%08llx]\n",
		  ni->mgmt_start_ba, ba2addr(ni, ni->mgmt_start_ba));

	/* Look for info table(s) */
	success = nmbm_load_info_table(ni, ni->mgmt_start_ba,
		ni->signature_ba);
	if (success) {
		nlog_info(ni, "NMBM has been successfully attached\n");
		return true;
	}

	if (!ni->force_create) {
		printk("not creating NMBM table\n");
		return false;
	}

	/* Fill block state table & mapping table */
	nmbm_scan_badblocks(ni);
	nmbm_build_mapping_table(ni);

	/* Write info table(s) */
	success = nmbm_create_info_table(ni);
	if (success) {
		nlog_info(ni, "NMBM has been successfully created\n");
		return true;
	}

	return false;
}

/*
 * nmbm_find_signature - Find signature in the lower NAND chip
 * @ni: NMBM instance structure
 * @signature_ba: used for storing block address of the signature
 * @signature_ba: return the actual block address of signature block
 *
 * Find a valid signature from a specific range in the lower NAND chip,
 * from bottom (highest address) to top (lowest address)
 *
 * Return true if found.
 */
static bool nmbm_find_signature(struct nmbm_instance *ni,
				struct nmbm_signature *signature,
				uint32_t *signature_ba)
{
	struct nmbm_signature sig;
	uint64_t off, addr;
	uint32_t block_count, ba, limit;
	bool success;
	int ret;

	/* Calculate top and bottom block address */
	block_count = bmtd.total_blks;
	ba = block_count;
	limit = (block_count / NMBM_MGMT_DIV) * (NMBM_MGMT_DIV - ni->max_ratio);
	if (ni->max_reserved_blocks && block_count - limit > ni->max_reserved_blocks)
		limit = block_count - ni->max_reserved_blocks;

	while (ba >= limit) {
		ba--;
		addr = ba2addr(ni, ba);

		if (nmbm_check_bad_phys_block(ni, ba))
			continue;

		/* Check every page.
		 * As long as at leaset one page contains valid signature,
		 * the block is treated as a valid signature block.
		 */
		for (off = 0; off < bmtd.blk_size;
		     off += bmtd.pg_size) {
			ret = nmbn_read_data(ni, addr + off, &sig,
					     sizeof(sig));
			if (ret)
				continue;

			/* Check for header size and checksum */
			success = nmbm_check_header(&sig, sizeof(sig));
			if (!success)
				continue;

			/* Check for header magic */
			if (sig.header.magic == NMBM_MAGIC_SIGNATURE) {
				/* Found it */
				memcpy(signature, &sig, sizeof(sig));
				*signature_ba = ba;
				return true;
			}
		}
	};

	return false;
}

/*
 * nmbm_calc_structure_size - Calculate the instance structure size
 * @nld: NMBM lower device structure
 */
static size_t nmbm_calc_structure_size(void)
{
	uint32_t state_table_size, mapping_table_size, info_table_size;
	uint32_t block_count;

	block_count = bmtd.total_blks;

	/* Calculate info table size */
	state_table_size = ((block_count + NMBM_BITMAP_BLOCKS_PER_UNIT - 1) /
		NMBM_BITMAP_BLOCKS_PER_UNIT) * NMBM_BITMAP_UNIT_SIZE;
	mapping_table_size = block_count * sizeof(int32_t);

	info_table_size = ALIGN(sizeof(struct nmbm_info_table_header),
				     bmtd.pg_size);
	info_table_size += ALIGN(state_table_size, bmtd.pg_size);
	info_table_size += ALIGN(mapping_table_size, bmtd.pg_size);

	return info_table_size + state_table_size + mapping_table_size +
		sizeof(struct nmbm_instance);
}

/*
 * nmbm_init_structure - Initialize members of instance structure
 * @ni: NMBM instance structure
 */
static void nmbm_init_structure(struct nmbm_instance *ni)
{
	uint32_t pages_per_block, blocks_per_chip;
	uintptr_t ptr;

	pages_per_block = bmtd.blk_size / bmtd.pg_size;
	blocks_per_chip = bmtd.total_blks;

	ni->rawpage_size = bmtd.pg_size + bmtd.mtd->oobsize;
	ni->rawblock_size = pages_per_block * ni->rawpage_size;
	ni->rawchip_size = blocks_per_chip * ni->rawblock_size;

	/* Calculate number of block this chip */
	ni->block_count = blocks_per_chip;

	/* Calculate info table size */
	ni->state_table_size = ((ni->block_count + NMBM_BITMAP_BLOCKS_PER_UNIT - 1) /
		NMBM_BITMAP_BLOCKS_PER_UNIT) * NMBM_BITMAP_UNIT_SIZE;
	ni->mapping_table_size = ni->block_count * sizeof(*ni->block_mapping);

	ni->info_table_size = ALIGN(sizeof(ni->info_table),
					 bmtd.pg_size);
	ni->info_table.state_table_off = ni->info_table_size;

	ni->info_table_size += ALIGN(ni->state_table_size,
					  bmtd.pg_size);
	ni->info_table.mapping_table_off = ni->info_table_size;

	ni->info_table_size += ALIGN(ni->mapping_table_size,
					  bmtd.pg_size);

	ni->info_table_spare_blocks = nmbm_get_spare_block_count(
		size2blk(ni, ni->info_table_size));

	/* Assign memory to members */
	ptr = (uintptr_t)ni + sizeof(*ni);

	ni->info_table_cache = (void *)ptr;
	ptr += ni->info_table_size;

	ni->block_state = (void *)ptr;
	ptr += ni->state_table_size;

	ni->block_mapping = (void *)ptr;
	ptr += ni->mapping_table_size;

	ni->page_cache = bmtd.data_buf;

	/* Initialize block state table */
	ni->block_state_changed = 0;
	memset(ni->block_state, 0xff, ni->state_table_size);

	/* Initialize block mapping table */
	ni->block_mapping_changed = 0;
}

/*
 * nmbm_attach - Attach to a lower device
 * @ni: NMBM instance structure
 */
static int nmbm_attach(struct nmbm_instance *ni)
{
	bool success;

	if (!ni)
		return -EINVAL;

	/* Initialize NMBM instance */
	nmbm_init_structure(ni);

	success = nmbm_find_signature(ni, &ni->signature, &ni->signature_ba);
	if (!success) {
		if (!ni->force_create) {
			nlog_err(ni, "Signature not found\n");
			return -ENODEV;
		}

		success = nmbm_create_new(ni);
		if (!success)
			return -ENODEV;

		return 0;
	}

	nlog_info(ni, "Signature found at block %u [0x%08llx]\n",
		 ni->signature_ba, ba2addr(ni, ni->signature_ba));

	if (ni->signature.header.version != NMBM_VER) {
		nlog_err(ni, "NMBM version %u.%u is not supported\n",
			NMBM_VERSION_MAJOR_GET(ni->signature.header.version),
			NMBM_VERSION_MINOR_GET(ni->signature.header.version));
		return -EINVAL;
	}

	if (ni->signature.nand_size != bmtd.total_blks << bmtd.blk_shift ||
	    ni->signature.block_size != bmtd.blk_size ||
	    ni->signature.page_size != bmtd.pg_size ||
	    ni->signature.spare_size != bmtd.mtd->oobsize) {
		nlog_err(ni, "NMBM configuration mismatch\n");
		return -EINVAL;
	}

	success = nmbm_load_existing(ni);
	if (!success)
		return -ENODEV;

	return 0;
}

static bool remap_block_nmbm(u16 block, u16 mapped_block, int copy_len)
{
	struct nmbm_instance *ni = bmtd.ni;
	int new_block;

	if (block >= ni->data_block_count)
		return false;

	nmbm_set_block_state(ni, mapped_block, BLOCK_ST_BAD);
	if (!nmbm_map_block(ni, block))
		return false;

	new_block = ni->block_mapping[block];
	bbt_nand_erase(new_block);
    if (copy_len > 0)
		bbt_nand_copy(new_block, mapped_block, copy_len);
	nmbm_update_info_table(ni);

	return true;
}

static int get_mapping_block_index_nmbm(int block)
{
	struct nmbm_instance *ni = bmtd.ni;

	if (block >= ni->data_block_count)
		return -1;

	return ni->block_mapping[block];
}

static int mtk_bmt_init_nmbm(struct device_node *np)
{
	struct nmbm_instance *ni;
	int ret;

	ni = kzalloc(nmbm_calc_structure_size(), GFP_KERNEL);
	if (!ni)
		return -ENOMEM;

	bmtd.ni = ni;

	if (of_property_read_u32(np, "mediatek,bmt-max-ratio", &ni->max_ratio))
		ni->max_ratio = 1;
	if (of_property_read_u32(np, "mediatek,bmt-max-reserved-blocks",
				 &ni->max_reserved_blocks))
		ni->max_reserved_blocks = 256;
	if (of_property_read_bool(np, "mediatek,empty-page-ecc-protected"))
		ni->empty_page_ecc_ok = true;
	if (of_property_read_bool(np, "mediatek,bmt-force-create"))
		ni->force_create = true;

	ret = nmbm_attach(ni);
	if (ret)
		goto out;

	bmtd.mtd->size = ni->data_block_count << bmtd.blk_shift;

	return 0;

out:
	kfree(ni);
	bmtd.ni = NULL;

	return ret;
}

static int mtk_bmt_debug_nmbm(void *data, u64 val)
{
	struct nmbm_instance *ni = bmtd.ni;
	int i;

	switch (val) {
	case 0:
		for (i = 1; i < ni->data_block_count; i++) {
			if (ni->block_mapping[i] < ni->mapping_blocks_ba)
				continue;

			printk("remap [%x->%x]\n", i, ni->block_mapping[i]);
		}
	}

	return 0;
}

static void unmap_block_nmbm(u16 block)
{
	struct nmbm_instance *ni = bmtd.ni;
	int start, offset;
	int new_block;

	if (block >= ni->data_block_count)
		return;

	start = block;
	offset = 0;
	while (ni->block_mapping[start] >= ni->mapping_blocks_ba) {
		start--;
		offset++;
		if (start < 0)
			return;
	}

	if (!offset)
		return;

	new_block = ni->block_mapping[start] + offset;
	nmbm_set_block_state(ni, new_block, BLOCK_ST_GOOD);
	ni->block_mapping[block] = new_block;
	ni->block_mapping_changed++;

	new_block = ni->signature_ba - 1;
	for (block = 0; block < ni->data_block_count; block++) {
		int cur = ni->block_mapping[block];

		if (cur < ni->mapping_blocks_ba)
			continue;

		if (cur <= new_block)
			new_block = cur - 1;
	}

	ni->mapping_blocks_top_ba = new_block;

	nmbm_update_info_table(ni);
}

const struct mtk_bmt_ops mtk_bmt_nmbm_ops = {
	.init = mtk_bmt_init_nmbm,
	.remap_block = remap_block_nmbm,
	.unmap_block = unmap_block_nmbm,
	.get_mapping_block = get_mapping_block_index_nmbm,
	.debug = mtk_bmt_debug_nmbm,
};