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nand_block_isbad

/**
 * nand_block_isbad - [MTD Interface] Check if block at offset is bad
 * @mtd: MTD device structure
 * @offs: offset relative to mtd start
 */
static int nand_block_isbad(struct mtd_info *mtd, loff_t offs)
{
	return nand_block_checkbad(mtd, offs, 1, 0);
}

nand_block_checkbad

/**
 * nand_block_checkbad - [GENERIC] Check if a block is marked bad
 * @mtd: MTD device structure
 * @ofs: offset from device start
 * @getchip: 0, if the chip is already selected
 * @allowbbt: 1, if its allowed to access the bbt area
 *
 * Check, if the block is bad. Either by reading the bad block table or
 * calling of the scan function.
 */
static int nand_block_checkbad(struct mtd_info *mtd, loff_t ofs, int getchip,
			       int allowbbt)
{
	struct nand_chip *chip = mtd->priv;

	if (!(chip->options & NAND_SKIP_BBTSCAN) &&
	    !(chip->options & NAND_BBT_SCANNED)) {
		chip->options |= NAND_BBT_SCANNED;
		chip->scan_bbt(mtd);
	}

	if (!chip->bbt)
		return chip->block_bad(mtd, ofs, getchip);

	/* Return info from the table */
	return nand_isbad_bbt(mtd, ofs, allowbbt);
}

nand_default_bbt

/**
 * nand_default_bbt - [NAND Interface] Select a default bad block table for the device
 * @mtd: MTD device structure
 *
 * This function selects the default bad block table support for the device and
 * calls the nand_scan_bbt function.
 */
int nand_default_bbt(struct mtd_info *mtd)
{
	struct nand_chip *this = mtd->priv;
	int ret;

	/* Is a flash based bad block table requested? */
	if (this->bbt_options & NAND_BBT_USE_FLASH) {
		/* Use the default pattern descriptors */
		if (!this->bbt_td) {
			if (this->bbt_options & NAND_BBT_NO_OOB) {
				this->bbt_td = &bbt_main_no_oob_descr;
				this->bbt_md = &bbt_mirror_no_oob_descr;
			} else {
				this->bbt_td = &bbt_main_descr;
				this->bbt_md = &bbt_mirror_descr;
			}
		}
	} else {
		this->bbt_td = NULL;
		this->bbt_md = NULL;
	}

	if (!this->badblock_pattern) {
		ret = nand_create_badblock_pattern(this);
		if (ret)
			return ret;
	}

	return nand_scan_bbt(mtd, this->badblock_pattern);
}

nand_scan_bbt

/**
 * nand_scan_bbt - [NAND Interface] scan, find, read and maybe create bad block table(s)
 * @mtd: MTD device structure
 * @bd: descriptor for the good/bad block search pattern
 *
 * The function checks, if a bad block table(s) is/are already available. If
 * not it scans the device for manufacturer marked good / bad blocks and writes
 * the bad block table(s) to the selected place.
 *
 * The bad block table memory is allocated here. It must be freed by calling
 * the nand_free_bbt function.
 */
int nand_scan_bbt(struct mtd_info *mtd, struct nand_bbt_descr *bd)
{
	struct nand_chip *this = mtd->priv;
	int len, res = 0;
	uint8_t *buf;
	struct nand_bbt_descr *td = this->bbt_td;
	struct nand_bbt_descr *md = this->bbt_md;

	len = mtd->size >> (this->bbt_erase_shift + 2);
	/*
	 * Allocate memory (2bit per block) and clear the memory bad block
	 * table.
	 */
	this->bbt = kzalloc(len, GFP_KERNEL);
	if (!this->bbt)
		return -ENOMEM;

	/*
	 * If no primary table decriptor is given, scan the device to build a
	 * memory based bad block table.
	 */
	if (!td) {
		if ((res = nand_memory_bbt(mtd, bd))) {
			pr_err("nand_bbt: can't scan flash and build the RAM-based BBT\n");
			kfree(this->bbt);
			this->bbt = NULL;
		}
		return res;
	}
	verify_bbt_descr(mtd, td);
	verify_bbt_descr(mtd, md);

	/* Allocate a temporary buffer for one eraseblock incl. oob */
	len = (1 << this->bbt_erase_shift);
	len += (len >> this->page_shift) * mtd->oobsize;
	buf = vmalloc(len);
	if (!buf) {
		kfree(this->bbt);
		this->bbt = NULL;
		return -ENOMEM;
	}

	/* Is the bbt at a given page? */
	if (td->options & NAND_BBT_ABSPAGE) {
		read_abs_bbts(mtd, buf, td, md);
	} else {
		/* Search the bad block table using a pattern in oob */
		search_read_bbts(mtd, buf, td, md);
	}

	res = check_create(mtd, buf, bd);

	/* Prevent the bbt regions from erasing / writing */
	mark_bbt_region(mtd, td);
	if (md)
		mark_bbt_region(mtd, md);

	vfree(buf);
	return res;
}

nand_memory_bbt

/**
 * nand_memory_bbt - [GENERIC] create a memory based bad block table
 * @mtd: MTD device structure
 * @bd: descriptor for the good/bad block search pattern
 *
 * The function creates a memory based bbt by scanning the device for
 * manufacturer / software marked good / bad blocks.
 */
static inline int nand_memory_bbt(struct mtd_info *mtd, struct nand_bbt_descr *bd)
{
	struct nand_chip *this = mtd->priv;

	return create_bbt(mtd, this->buffers->databuf, bd, -1);
}

create_bbt

/**
 * create_bbt - [GENERIC] Create a bad block table by scanning the device
 * @mtd: MTD device structure
 * @buf: temporary buffer
 * @bd: descriptor for the good/bad block search pattern
 * @chip: create the table for a specific chip, -1 read all chips; applies only
 *        if NAND_BBT_PERCHIP option is set
 *
 * Create a bad block table by scanning the device for the given good/bad block
 * identify pattern.
 */
static int create_bbt(struct mtd_info *mtd, uint8_t *buf,
	struct nand_bbt_descr *bd, int chip)
{
	struct nand_chip *this = mtd->priv;
	int i, numblocks, numpages;
	int startblock;
	loff_t from;

	pr_info("Scanning device for bad blocks\n");

	if (bd->options & NAND_BBT_SCAN2NDPAGE)
		numpages = 2;
	else
		numpages = 1;

	if (chip == -1) {
		numblocks = mtd->size >> this->bbt_erase_shift;
		startblock = 0;
		from = 0;
	} else {
		if (chip >= this->numchips) {
			pr_warn("create_bbt(): chipnr (%d) > available chips (%d)\n",
			       chip + 1, this->numchips);
			return -EINVAL;
		}
		numblocks = this->chipsize >> this->bbt_erase_shift;
		startblock = chip * numblocks;
		numblocks += startblock;
		from = (loff_t)startblock << this->bbt_erase_shift;
	}

	if (this->bbt_options & NAND_BBT_SCANLASTPAGE)
		from += mtd->erasesize - (mtd->writesize * numpages);

	for (i = startblock; i < numblocks; i++) {
		int ret;

		BUG_ON(bd->options & NAND_BBT_NO_OOB);

		ret = scan_block_fast(mtd, bd, from, buf, numpages);
		if (ret < 0)
			return ret;

		if (ret) {
			bbt_mark_entry(this, i, BBT_BLOCK_FACTORY_BAD);
			pr_warn("Bad eraseblock %d at 0x%012llx\n",
				i, (unsigned long long)from);
			mtd->ecc_stats.badblocks++;
		}

		from += (1 << this->bbt_erase_shift);
	}
	return 0;
}

check_create

/**
 * check_create - [GENERIC] create and write bbt(s) if necessary
 * @mtd: MTD device structure
 * @buf: temporary buffer
 * @bd: descriptor for the good/bad block search pattern
 *
 * The function checks the results of the previous call to read_bbt and creates
 * / updates the bbt(s) if necessary. Creation is necessary if no bbt was found
 * for the chip/device. Update is necessary if one of the tables is missing or
 * the version nr. of one table is less than the other.
 */
static int check_create(struct mtd_info *mtd, uint8_t *buf, struct nand_bbt_descr *bd)
{
	int i, chips, writeops, create, chipsel, res, res2;
	struct nand_chip *this = mtd->priv;
	struct nand_bbt_descr *td = this->bbt_td;
	struct nand_bbt_descr *md = this->bbt_md;
	struct nand_bbt_descr *rd, *rd2;

	/* Do we have a bbt per chip? */
	if (td->options & NAND_BBT_PERCHIP)
		chips = this->numchips;
	else
		chips = 1;

	for (i = 0; i < chips; i++) {
		writeops = 0;
		create = 0;
		rd = NULL;
		rd2 = NULL;
		res = res2 = 0;
		/* Per chip or per device? */
		chipsel = (td->options & NAND_BBT_PERCHIP) ? i : -1;
		/* Mirrored table available? */
		if (md) {
			if (td->pages[i] == -1 && md->pages[i] == -1) {
				create = 1;
				writeops = 0x03;
			} else if (td->pages[i] == -1) {
				rd = md;
				writeops = 0x01;
			} else if (md->pages[i] == -1) {
				rd = td;
				writeops = 0x02;
			} else if (td->version[i] == md->version[i]) {
				rd = td;
				if (!(td->options & NAND_BBT_VERSION))
					rd2 = md;
			} else if (((int8_t)(td->version[i] - md->version[i])) > 0) {
				rd = td;
				writeops = 0x02;
			} else {
				rd = md;
				writeops = 0x01;
			}
		} else {
			if (td->pages[i] == -1) {
				create = 1;
				writeops = 0x01;
			} else {
				rd = td;
			}
		}

		if (create) {
			/* Create the bad block table by scanning the device? */
			if (!(td->options & NAND_BBT_CREATE))
				continue;

			/* Create the table in memory by scanning the chip(s) */
			if (!(this->bbt_options & NAND_BBT_CREATE_EMPTY))
				create_bbt(mtd, buf, bd, chipsel);

			td->version[i] = 1;
			if (md)
				md->version[i] = 1;
		}

		/* Read back first? */
		if (rd) {
			res = read_abs_bbt(mtd, buf, rd, chipsel);
			if (mtd_is_eccerr(res)) {
				/* Mark table as invalid */
				rd->pages[i] = -1;
				rd->version[i] = 0;
				i--;
				continue;
			}
		}
		/* If they weren't versioned, read both */
		if (rd2) {
			res2 = read_abs_bbt(mtd, buf, rd2, chipsel);
			if (mtd_is_eccerr(res2)) {
				/* Mark table as invalid */
				rd2->pages[i] = -1;
				rd2->version[i] = 0;
				i--;
				continue;
			}
		}

		/* Scrub the flash table(s)? */
		if (mtd_is_bitflip(res) || mtd_is_bitflip(res2))
			writeops = 0x03;

		/* Update version numbers before writing */
		if (md) {
			td->version[i] = max(td->version[i], md->version[i]);
			md->version[i] = td->version[i];
		}

		/* Write the bad block table to the device? */
		if ((writeops & 0x01) && (td->options & NAND_BBT_WRITE)) {
			res = write_bbt(mtd, buf, td, md, chipsel);
			if (res < 0)
				return res;
		}

		/* Write the mirror bad block table to the device? */
		if ((writeops & 0x02) && md && (md->options & NAND_BBT_WRITE)) {
			res = write_bbt(mtd, buf, md, td, chipsel);
			if (res < 0)
				return res;
		}
	}
	return 0;
}

write_bbt

/**
 * write_bbt - [GENERIC] (Re)write the bad block table
 * @mtd: MTD device structure
 * @buf: temporary buffer
 * @td: descriptor for the bad block table
 * @md: descriptor for the bad block table mirror
 * @chipsel: selector for a specific chip, -1 for all
 *
 * (Re)write the bad block table.
 */
static int write_bbt(struct mtd_info *mtd, uint8_t *buf,
		     struct nand_bbt_descr *td, struct nand_bbt_descr *md,
		     int chipsel)
{
	struct nand_chip *this = mtd->priv;
	struct erase_info einfo;
	int i, res, chip = 0;
	int bits, startblock, dir, page, offs, numblocks, sft, sftmsk;
	int nrchips, pageoffs, ooboffs;
	uint8_t msk[4];
	uint8_t rcode = td->reserved_block_code;
	size_t retlen, len = 0;
	loff_t to;
	struct mtd_oob_ops ops;

	ops.ooblen = mtd->oobsize;
	ops.ooboffs = 0;
	ops.datbuf = NULL;
	ops.mode = MTD_OPS_PLACE_OOB;

	if (!rcode)
		rcode = 0xff;
	/* Write bad block table per chip rather than per device? */
	if (td->options & NAND_BBT_PERCHIP) {
		numblocks = (int)(this->chipsize >> this->bbt_erase_shift);
		/* Full device write or specific chip? */
		if (chipsel == -1) {
			nrchips = this->numchips;
		} else {
			nrchips = chipsel + 1;
			chip = chipsel;
		}
	} else {
		numblocks = (int)(mtd->size >> this->bbt_erase_shift);
		nrchips = 1;
	}

	/* Loop through the chips */
	for (; chip < nrchips; chip++) {
		/*
		 * There was already a version of the table, reuse the page
		 * This applies for absolute placement too, as we have the
		 * page nr. in td->pages.
		 */
		if (td->pages[chip] != -1) {
			page = td->pages[chip];
			goto write;
		}

		/*
		 * Automatic placement of the bad block table. Search direction
		 * top -> down?
		 */
		if (td->options & NAND_BBT_LASTBLOCK) {
			startblock = numblocks * (chip + 1) - 1;
			dir = -1;
		} else {
			startblock = chip * numblocks;
			dir = 1;
		}

		for (i = 0; i < td->maxblocks; i++) {
			int block = startblock + dir * i;
			/* Check, if the block is bad */
			switch (bbt_get_entry(this, block)) {
			case BBT_BLOCK_WORN:
			case BBT_BLOCK_FACTORY_BAD:
				continue;
			}
			page = block <<
				(this->bbt_erase_shift - this->page_shift);
			/* Check, if the block is used by the mirror table */
			if (!md || md->pages[chip] != page)
				goto write;
		}
		pr_err("No space left to write bad block table\n");
		return -ENOSPC;
	write:

		/* Set up shift count and masks for the flash table */
		bits = td->options & NAND_BBT_NRBITS_MSK;
		msk[2] = ~rcode;
		switch (bits) {
		case 1: sft = 3; sftmsk = 0x07; msk[0] = 0x00; msk[1] = 0x01;
			msk[3] = 0x01;
			break;
		case 2: sft = 2; sftmsk = 0x06; msk[0] = 0x00; msk[1] = 0x01;
			msk[3] = 0x03;
			break;
		case 4: sft = 1; sftmsk = 0x04; msk[0] = 0x00; msk[1] = 0x0C;
			msk[3] = 0x0f;
			break;
		case 8: sft = 0; sftmsk = 0x00; msk[0] = 0x00; msk[1] = 0x0F;
			msk[3] = 0xff;
			break;
		default: return -EINVAL;
		}

		to = ((loff_t)page) << this->page_shift;

		/* Must we save the block contents? */
		if (td->options & NAND_BBT_SAVECONTENT) {
			/* Make it block aligned */
			to &= ~((loff_t)((1 << this->bbt_erase_shift) - 1));
			len = 1 << this->bbt_erase_shift;
			res = mtd_read(mtd, to, len, &retlen, buf);
			if (res < 0) {
				if (retlen != len) {
					pr_info("nand_bbt: error reading block for writing the bad block table\n");
					return res;
				}
				pr_warn("nand_bbt: ECC error while reading block for writing bad block table\n");
			}
			/* Read oob data */
			ops.ooblen = (len >> this->page_shift) * mtd->oobsize;
			ops.oobbuf = &buf[len];
			res = mtd_read_oob(mtd, to + mtd->writesize, &ops);
			if (res < 0 || ops.oobretlen != ops.ooblen)
				goto outerr;

			/* Calc the byte offset in the buffer */
			pageoffs = page - (int)(to >> this->page_shift);
			offs = pageoffs << this->page_shift;
			/* Preset the bbt area with 0xff */
			memset(&buf[offs], 0xff, (size_t)(numblocks >> sft));
			ooboffs = len + (pageoffs * mtd->oobsize);

		} else if (td->options & NAND_BBT_NO_OOB) {
			ooboffs = 0;
			offs = td->len;
			/* The version byte */
			if (td->options & NAND_BBT_VERSION)
				offs++;
			/* Calc length */
			len = (size_t)(numblocks >> sft);
			len += offs;
			/* Make it page aligned! */
			len = ALIGN(len, mtd->writesize);
			/* Preset the buffer with 0xff */
			memset(buf, 0xff, len);
			/* Pattern is located at the begin of first page */
			memcpy(buf, td->pattern, td->len);
		} else {
			/* Calc length */
			len = (size_t)(numblocks >> sft);
			/* Make it page aligned! */
			len = ALIGN(len, mtd->writesize);
			/* Preset the buffer with 0xff */
			memset(buf, 0xff, len +
			       (len >> this->page_shift)* mtd->oobsize);
			offs = 0;
			ooboffs = len;
			/* Pattern is located in oob area of first page */
			memcpy(&buf[ooboffs + td->offs], td->pattern, td->len);
		}

		if (td->options & NAND_BBT_VERSION)
			buf[ooboffs + td->veroffs] = td->version[chip];

		/* Walk through the memory table */
		for (i = 0; i < numblocks; i++) {
			uint8_t dat;
			int sftcnt = (i << (3 - sft)) & sftmsk;
			dat = bbt_get_entry(this, chip * numblocks + i);
			/* Do not store the reserved bbt blocks! */
			buf[offs + (i >> sft)] &= ~(msk[dat] << sftcnt);
		}

		memset(&einfo, 0, sizeof(einfo));
		einfo.mtd = mtd;
		einfo.addr = to;
		einfo.len = 1 << this->bbt_erase_shift;
		res = nand_erase_nand(mtd, &einfo, 1);
		if (res < 0)
			goto outerr;

		res = scan_write_bbt(mtd, to, len, buf,
				td->options & NAND_BBT_NO_OOB ? NULL :
				&buf[len]);
		if (res < 0)
			goto outerr;

		pr_info("Bad block table written to 0x%012llx, version 0x%02X\n",
			 (unsigned long long)to, td->version[chip]);

		/* Mark it as used */
		td->pages[chip] = page;
	}
	return 0;

 outerr:
	pr_warn("nand_bbt: error while writing bad block table %d\n", res);
	return res;
}

nand_block_bad

/**
 * nand_block_bad - [DEFAULT] Read bad block marker from the chip
 * @mtd: MTD device structure
 * @ofs: offset from device start
 * @getchip: 0, if the chip is already selected
 *
 * Check, if the block is bad.
 */
static int nand_block_bad(struct mtd_info *mtd, loff_t ofs, int getchip)
{
	int page, chipnr, res = 0, i = 0;
	struct nand_chip *chip = mtd->priv;
	u16 bad;

	if (chip->bbt_options & NAND_BBT_SCANLASTPAGE)
		ofs += mtd->erasesize - mtd->writesize;

	page = (int)(ofs >> chip->page_shift) & chip->pagemask;

	if (getchip) {
		chipnr = (int)(ofs >> chip->chip_shift);

		nand_get_device(mtd, FL_READING);

		/* Select the NAND device */
		chip->select_chip(mtd, chipnr);
	}

	do {
		if (chip->options & NAND_BUSWIDTH_16) {
			chip->cmdfunc(mtd, NAND_CMD_READOOB,
					chip->badblockpos & 0xFE, page);
			bad = cpu_to_le16(chip->read_word(mtd));
			if (chip->badblockpos & 0x1)
				bad >>= 8;
			else
				bad &= 0xFF;
		} else {
			chip->cmdfunc(mtd, NAND_CMD_READOOB, chip->badblockpos,
					page);
			bad = chip->read_byte(mtd);
		}

		if (likely(chip->badblockbits == 8))
			res = bad != 0xFF;
		else
			res = hweight8(bad) < chip->badblockbits;
		ofs += mtd->writesize;
		page = (int)(ofs >> chip->page_shift) & chip->pagemask;
		i++;
	} while (!res && i < 2 && (chip->bbt_options & NAND_BBT_SCAN2NDPAGE));

	if (getchip) {
		chip->select_chip(mtd, -1);
		nand_release_device(mtd);
	}

	return res;
}

nand_isbad_bbt

/**
 * nand_isbad_bbt - [NAND Interface] Check if a block is bad
 * @mtd: MTD device structure
 * @offs: offset in the device
 * @allowbbt: allow access to bad block table region
 */
int nand_isbad_bbt(struct mtd_info *mtd, loff_t offs, int allowbbt)
{
	struct nand_chip *this = mtd->priv;
	int block, res;

	block = (int)(offs >> this->bbt_erase_shift);
	res = bbt_get_entry(this, block);

	pr_debug("nand_isbad_bbt(): bbt info for offs 0x%08x: (block %d) 0x%02x\n",
		 (unsigned int)offs, block, res);

	switch (res) {
	case BBT_BLOCK_GOOD:
		return 0;
	case BBT_BLOCK_WORN:
		return 1;
	case BBT_BLOCK_RESERVED:
		return allowbbt ? 0 : 1;
	}
	return 1;
}

bbt_get_entry

static inline uint8_t bbt_get_entry(struct nand_chip *chip, int block)
{
	uint8_t entry = chip->bbt[block >> BBT_ENTRY_SHIFT];
	entry >>= (block & BBT_ENTRY_MASK) * 2;
	return entry & BBT_ENTRY_MASK;
}