nand_bbt.c

老版本的mtd-snap

		td->version[i] = 1;
		if (md)
			md->version[i] = 1;	
writecheck:	
		/* read back first ? */
		if (rd)
			read_abs_bbt (mtd, buf, rd, chipsel);
		/* If they weren't versioned, read both. */
		if (rd2)
			read_abs_bbt (mtd, buf, rd2, chipsel);

		/* 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;	
}

/**
 * mark_bbt_regions - [GENERIC] mark the bad block table regions 
 * @mtd:	MTD device structure
 * @td:		bad block table descriptor
 *
 * The bad block table regions are marked as "bad" to prevent
 * accidental erasures / writes. The regions are identified by
 * the mark 0x02.
*/
static void mark_bbt_region (struct mtd_info *mtd, struct nand_bbt_descr *td)
{
	struct nand_chip *this = mtd->priv;
	int i, j, chips, block, nrblocks, update;
	uint8_t oldval, newval;

	/* Do we have a bbt per chip ? */
	if (td->options & NAND_BBT_PERCHIP) {
		chips = this->numchips;
		nrblocks = (int)(this->chipsize >> this->bbt_erase_shift);
	} else {
		chips = 1;
		nrblocks = (int)(mtd->size >> this->bbt_erase_shift);
	}	
	
	for (i = 0; i < chips; i++) {
		if ((td->options & NAND_BBT_ABSPAGE) ||
		    !(td->options & NAND_BBT_WRITE)) {
		    	if (td->pages[i] == -1) continue;
			block = td->pages[i] >> (this->bbt_erase_shift - this->page_shift);
			block <<= 1;		
			oldval = this->bbt[(block >> 3)];
			newval = oldval | (0x2 << (block & 0x06));
			this->bbt[(block >> 3)] = newval;
			if ((oldval != newval) && td->reserved_block_code)
				nand_update_bbt(mtd, block << (this->bbt_erase_shift - 1));
			continue;
		}
		update = 0;
		if (td->options & NAND_BBT_LASTBLOCK)
			block = ((i + 1) * nrblocks) - td->maxblocks;
		else	
			block = i * nrblocks;
		block <<= 1;	
		for (j = 0; j < td->maxblocks; j++) {
			oldval = this->bbt[(block >> 3)];
			newval = oldval | (0x2 << (block & 0x06));
			this->bbt[(block >> 3)] = newval;
			if (oldval != newval) update = 1;
			block += 2;
		}	
		/* If we want reserved blocks to be recorded to flash, and some
		   new ones have been marked, then we need to update the stored
		   bbts.  This should only happen once. */
		if (update && td->reserved_block_code)
			nand_update_bbt(mtd, (block - 2) << (this->bbt_erase_shift - 1));
	}
}

/**
 * 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) */
	this->bbt = kmalloc (len, GFP_KERNEL);
	if (!this->bbt) {
		printk (KERN_ERR "nand_scan_bbt: Out of memory\n");
		return -ENOMEM;
	}
	/* Clear the memory bad block table */
	memset (this->bbt, 0x00, len);

	/* 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))) {
			printk (KERN_ERR "nand_bbt: Can't scan flash and build the RAM-based BBT\n");
			kfree (this->bbt);
			this->bbt = NULL;
		}
		return res;
	}

	/* Allocate a temporary buffer for one eraseblock incl. oob */
	len = (1 << this->bbt_erase_shift);
	len += (len >> this->page_shift) * mtd->oobsize;
	buf = kmalloc (len, GFP_KERNEL);
	if (!buf) {
		printk (KERN_ERR "nand_bbt: Out of memory\n");
		kfree (this->bbt);
		this->bbt = NULL;
		return -ENOMEM;
	}
	
	/* Is the bbt at a given page ? */
	if (td->options & NAND_BBT_ABSPAGE) {
		res = read_abs_bbts (mtd, buf, td, md);
	} else {	
		/* Search the bad block table using a pattern in oob */
		res = search_read_bbts (mtd, buf, td, md);
	}	

	if (res) 
		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);
	
	kfree (buf);
	return res;
}


/**
 * nand_update_bbt - [NAND Interface] update bad block table(s) 
 * @mtd:	MTD device structure
 * @offs:	the offset of the newly marked block
 *
 * The function updates the bad block table(s)
*/
int nand_update_bbt (struct mtd_info *mtd, loff_t offs)
{
	struct nand_chip *this = mtd->priv;
	int len, res = 0, writeops = 0;
	int chip, chipsel;
	uint8_t *buf;
	struct nand_bbt_descr *td = this->bbt_td;
	struct nand_bbt_descr *md = this->bbt_md;

	if (!this->bbt || !td)
		return -EINVAL;

	len = mtd->size >> (this->bbt_erase_shift + 2);
	/* Allocate a temporary buffer for one eraseblock incl. oob */
	len = (1 << this->bbt_erase_shift);
	len += (len >> this->page_shift) * mtd->oobsize;
	buf = kmalloc (len, GFP_KERNEL);
	if (!buf) {
		printk (KERN_ERR "nand_update_bbt: Out of memory\n");
		return -ENOMEM;
	}
	
	writeops = md != NULL ? 0x03 : 0x01;

	/* Do we have a bbt per chip ? */
	if (td->options & NAND_BBT_PERCHIP) {
		chip = (int) (offs >> this->chip_shift);
		chipsel = chip;
	} else {
		chip = 0;
		chipsel = -1;
	}

	td->version[chip]++;
	if (md)
		md->version[chip]++;	

	/* 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)
			goto out;
	}
	/* 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);
	}

out:	
	kfree (buf);
	return res;
}

/* Define some generic bad / good block scan pattern which are used 
 * while scanning a device for factory marked good / bad blocks. */
static uint8_t scan_ff_pattern[] = { 0xff, 0xff };

static struct nand_bbt_descr smallpage_memorybased = {
	.options = NAND_BBT_SCAN2NDPAGE,
	.offs = 5,
	.len = 1,
	.pattern = scan_ff_pattern
};

static struct nand_bbt_descr largepage_memorybased = {
	.options = 0,
	.offs = 0,
	.len = 2,
	.pattern = scan_ff_pattern
};

static struct nand_bbt_descr smallpage_flashbased = {
	.options = NAND_BBT_SCANEMPTY | NAND_BBT_SCANALLPAGES,
	.offs = 5,
	.len = 1,
	.pattern = scan_ff_pattern
};

static struct nand_bbt_descr largepage_flashbased = {
	.options = NAND_BBT_SCANEMPTY | NAND_BBT_SCANALLPAGES,
	.offs = 0,
	.len = 2,
	.pattern = scan_ff_pattern
};

static uint8_t scan_agand_pattern[] = { 0x1C, 0x71, 0xC7, 0x1C, 0x71, 0xC7 };

static struct nand_bbt_descr agand_flashbased = {
	.options = NAND_BBT_SCANEMPTY | NAND_BBT_SCANALLPAGES,
	.offs = 0x20,
	.len = 6,
	.pattern = scan_agand_pattern
};

/* Generic flash bbt decriptors
*/
static uint8_t bbt_pattern[] = {'B', 'b', 't', '0' };
static uint8_t mirror_pattern[] = {'1', 't', 'b', 'B' };

static struct nand_bbt_descr bbt_main_descr = {
	.options = NAND_BBT_LASTBLOCK | NAND_BBT_CREATE | NAND_BBT_WRITE 
		| NAND_BBT_2BIT | NAND_BBT_VERSION | NAND_BBT_PERCHIP,
	.offs =	8,
	.len = 4,
	.veroffs = 12,
	.maxblocks = 4,
	.pattern = bbt_pattern
};

static struct nand_bbt_descr bbt_mirror_descr = {
	.options = NAND_BBT_LASTBLOCK | NAND_BBT_CREATE | NAND_BBT_WRITE 
		| NAND_BBT_2BIT | NAND_BBT_VERSION | NAND_BBT_PERCHIP,
	.offs =	8,
	.len = 4,
	.veroffs = 12,
	.maxblocks = 4,
	.pattern = mirror_pattern
};

/**
 * 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;
	
	/* Default for AG-AND. We must use a flash based 
	 * bad block table as the devices have factory marked
	 * _good_ blocks. Erasing those blocks leads to loss
	 * of the good / bad information, so we _must_ store
	 * this information in a good / bad table during 
	 * startup
	*/
	if (this->options & NAND_IS_AND) {
		/* Use the default pattern descriptors */
		if (!this->bbt_td) {	
			this->bbt_td = &bbt_main_descr;
			this->bbt_md = &bbt_mirror_descr;
		}	
		this->options |= NAND_USE_FLASH_BBT;
		return nand_scan_bbt (mtd, &agand_flashbased);
	}
	
	
	/* Is a flash based bad block table requested ? */
	if (this->options & NAND_USE_FLASH_BBT) {
		/* Use the default pattern descriptors */	
		if (!this->bbt_td) {	
			this->bbt_td = &bbt_main_descr;
			this->bbt_md = &bbt_mirror_descr;
		}
		if (!this->badblock_pattern) {
			this->badblock_pattern = (mtd->oobblock > 512) ?
				&largepage_flashbased : &smallpage_flashbased;
		}
	} else {
		this->bbt_td = NULL;
		this->bbt_md = NULL;
		if (!this->badblock_pattern) {
			this->badblock_pattern = (mtd->oobblock > 512) ?
				&largepage_memorybased : &smallpage_memorybased;
		}
	}
	return nand_scan_bbt (mtd, this->badblock_pattern);
}

/**
 * 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;
	uint8_t	res;
	
	/* Get block number * 2 */
	block = (int) (offs >> (this->bbt_erase_shift - 1));
	res = (this->bbt[block >> 3] >> (block & 0x06)) & 0x03;

	DEBUG (MTD_DEBUG_LEVEL2, "nand_isbad_bbt(): bbt info for offs 0x%08x: (block %d) 0x%02x\n", 
		(unsigned int)offs, block >> 1, res);

	switch ((int)res) {
	case 0x00:	return 0;
	case 0x01:	return 1;
	case 0x02:	return allowbbt ? 0 : 1;
	}
	return 1;
}

EXPORT_SYMBOL (nand_scan_bbt);
EXPORT_SYMBOL (nand_default_bbt);