nand_bbt.c

老版本的mtd-snap

 * Search is preformed either from the beginning up or from the end of 
 * the device downwards. The search starts always at the start of a
 * block.
 * If the option NAND_BBT_PERCHIP is given, each chip is searched 
 * for a bbt, which contains the bad block information of this chip.
 * This is neccecary to provide support for certain DOC devices.
 *
 * The bbt ident pattern resides in the oob area of the first page 
 * in a block. 
 */
static int search_bbt (struct mtd_info *mtd, uint8_t *buf, struct nand_bbt_descr *td)
{
	struct nand_chip *this = mtd->priv;
	int i, chips;
	int bits, startblock, block, dir;
	int scanlen = mtd->oobblock + mtd->oobsize;
	int bbtblocks;

	/* Search direction top -> down ? */
	if (td->options & NAND_BBT_LASTBLOCK) {
		startblock = (mtd->size >> this->bbt_erase_shift) -1;
		dir = -1;
	} else {
		startblock = 0;	
		dir = 1;
	}	
	
	/* Do we have a bbt per chip ? */
	if (td->options & NAND_BBT_PERCHIP) {
		chips = this->numchips;
		bbtblocks = this->chipsize >> this->bbt_erase_shift;
		startblock &= bbtblocks - 1;
	} else {
		chips = 1;
		bbtblocks = mtd->size >> this->bbt_erase_shift;
	}
	
	/* Number of bits for each erase block in the bbt */
	bits = td->options & NAND_BBT_NRBITS_MSK;
	
	for (i = 0; i < chips; i++) {
		/* Reset version information */
		td->version[i] = 0;	
		td->pages[i] = -1;
		/* Scan the maximum number of blocks */
		for (block = 0; block < td->maxblocks; block++) {
			int actblock = startblock + dir * block;
			/* Read first page */
			nand_read_raw (mtd, buf, actblock << this->bbt_erase_shift, mtd->oobblock, mtd->oobsize); 
			if (!check_pattern(buf, scanlen, mtd->oobblock, td)) {
				td->pages[i] = actblock << (this->bbt_erase_shift - this->page_shift);
				if (td->options & NAND_BBT_VERSION) {
					td->version[i] = buf[mtd->oobblock + td->veroffs];
				}
				break;
			}
		}
		startblock += this->chipsize >> this->bbt_erase_shift;
	}
	/* Check, if we found a bbt for each requested chip */
	for (i = 0; i < chips; i++) {
		if (td->pages[i] == -1)
			printk (KERN_WARNING "Bad block table not found for chip %d\n", i);
		else
			printk (KERN_DEBUG "Bad block table found at page %d, version 0x%02X\n", td->pages[i], td->version[i]);
	}
	return 0;	
}

/**
 * search_read_bbts - [GENERIC] scan the device for bad block table(s)
 * @mtd:	MTD device structure
 * @buf:	temporary buffer
 * @td:		descriptor for the bad block table 
 * @md:		descriptor for the bad block table mirror
 *
 * Search and read the bad block table(s)
*/
static int search_read_bbts (struct mtd_info *mtd, uint8_t *buf, 
	struct nand_bbt_descr *td, struct nand_bbt_descr *md)
{
	/* Search the primary table */
	search_bbt (mtd, buf, td);
		
	/* Search the mirror table */
	if (md)
		search_bbt (mtd, buf, md);
	
	/* Force result check */
	return 1;	
}
	

/** 
 * 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 nand_oobinfo oobinfo;
	struct erase_info einfo;
	int i, j, res, chip = 0;
	int bits, startblock, dir, page, offs, numblocks, sft, sftmsk;
	int nrchips, bbtoffs, pageoffs;
	uint8_t msk[4];
	uint8_t rcode = td->reserved_block_code;
	size_t retlen, len = 0;
	loff_t to;

	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 ((this->bbt[block >> 2] >> (2 * (block & 0x03))) & 0x03) {
			case 0x01:
			case 0x03:
				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;
		}
		printk (KERN_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;
		switch (bits) {
		case 1: sft = 3; sftmsk = 0x07; msk[0] = 0x00; msk[1] = 0x01; msk[2] = ~rcode; msk[3] = 0x01; break;
		case 2: sft = 2; sftmsk = 0x06; msk[0] = 0x00; msk[1] = 0x01; msk[2] = ~rcode; msk[3] = 0x03; break;
		case 4: sft = 1; sftmsk = 0x04; msk[0] = 0x00; msk[1] = 0x0C; msk[2] = ~rcode; msk[3] = 0x0f; break;
		case 8: sft = 0; sftmsk = 0x00; msk[0] = 0x00; msk[1] = 0x0F; msk[2] = ~rcode; msk[3] = 0xff; break;
		default: return -EINVAL;
		}
		
		bbtoffs = chip * (numblocks >> 2);
		
		to = ((loff_t) page) << this->page_shift;

		memcpy (&oobinfo, this->autooob, sizeof(oobinfo));
		oobinfo.useecc = MTD_NANDECC_PLACEONLY;
		
		/* 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_ecc (mtd, to, len, &retlen, buf, &buf[len], &oobinfo);
			if (res < 0) {
				if (retlen != len) {
					printk (KERN_INFO "nand_bbt: Error reading block for writing the bad block table\n");
					return res;
				}
				printk (KERN_WARNING "nand_bbt: ECC error while reading block for writing bad block table\n");
			}
			/* 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));
			/* Preset the bbt's oob area with 0xff */
			memset (&buf[len + pageoffs * mtd->oobsize], 0xff,
				((len >> this->page_shift) - pageoffs) * mtd->oobsize);
			if (td->options & NAND_BBT_VERSION) {
				buf[len + (pageoffs * mtd->oobsize) + td->veroffs] = td->version[chip];
			}
		} else {
			/* Calc length */
			len = (size_t) (numblocks >> sft);
			/* Make it page aligned ! */
			len = (len + (mtd->oobblock-1)) & ~(mtd->oobblock-1);
			/* Preset the buffer with 0xff */
			memset (buf, 0xff, len + (len >> this->page_shift) * mtd->oobsize);
			offs = 0;
			/* Pattern is located in oob area of first page */
			memcpy (&buf[len + td->offs], td->pattern, td->len);
			if (td->options & NAND_BBT_VERSION) {
				buf[len + td->veroffs] = td->version[chip];
			}
		}
	
		/* walk through the memory table */
		for (i = 0; i < numblocks; ) {
			uint8_t dat;
			dat = this->bbt[bbtoffs + (i >> 2)];
			for (j = 0; j < 4; j++ , i++) {
				int sftcnt = (i << (3 - sft)) & sftmsk;
				/* Do not store the reserved bbt blocks ! */
				buf[offs + (i >> sft)] &= ~(msk[dat & 0x03] << sftcnt);
				dat >>= 2;
			}
		}
		
		memset (&einfo, 0, sizeof (einfo));
		einfo.mtd = mtd;
		einfo.addr = (unsigned long) to;
		einfo.len = 1 << this->bbt_erase_shift;
		res = nand_erase_nand (mtd, &einfo, 1);
		if (res < 0) {
			printk (KERN_WARNING "nand_bbt: Error during block erase: %d\n", res);
			return res;
		}
	
		res = mtd->write_ecc (mtd, to, len, &retlen, buf, &buf[len], &oobinfo);
		if (res < 0) {
			printk (KERN_WARNING "nand_bbt: Error while writing bad block table %d\n", res);
			return res;
		}
		printk (KERN_DEBUG "Bad block table written to 0x%08x, version 0x%02X\n", 
			(unsigned int) to, td->version[chip]);
	
		/* Mark it as used */
		td->pages[chip] = page;
	}	
	return 0;
}

/**
 * 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;

	bd->options &= ~NAND_BBT_SCANEMPTY;
	return create_bbt (mtd, this->data_buf, bd, -1);
}

/**
 * check_create - [GENERIC] create and write bbt(s) if neccecary
 * @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 neccecary
 * Creation is neccecary if no bbt was found for the chip/device
 * Update is neccecary 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, chipsel, res;
	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;
		rd = NULL;
		rd2 = NULL;
		/* Per chip or per device ? */
		chipsel = (td->options & NAND_BBT_PERCHIP) ? i : -1;
		/* Mirrored table avilable ? */
		if (md) {
			if (td->pages[i] == -1 && md->pages[i] == -1) {
				writeops = 0x03;
				goto create;
			}

			if (td->pages[i] == -1) {
				rd = md;				
				td->version[i] = md->version[i];
				writeops = 1;
				goto writecheck;
			}

			if (md->pages[i] == -1) {
				rd = td;
				md->version[i] = td->version[i];
				writeops = 2;
				goto writecheck;
			}

			if (td->version[i] == md->version[i]) {
				rd = td;
				if (!(td->options & NAND_BBT_VERSION))
					rd2 = md;
				goto writecheck;
			}	

			if (((int8_t) (td->version[i] - md->version[i])) > 0) {
				rd = td;
				md->version[i] = td->version[i];
				writeops = 2;
			} else {
				rd = md;
				td->version[i] = md->version[i];
				writeops = 1;
			}

			goto writecheck;

		} else {
			if (td->pages[i] == -1) {
				writeops = 0x01;
				goto create;
			}
			rd = td;
			goto writecheck;
		}
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) */
		create_bbt (mtd, buf, bd, chipsel);