nand_base.c

					int idx = oobsel->eccpos[i];
					if (oobdata[idx] != oob_buf[oobofs + idx] ) {
						DEBUG (MTD_DEBUG_LEVEL0,
					       	"%s: Failed ECC write "
						"verify, page 0x%08x, " "%6i bytes were succesful\n", __FUNCTION__, page, i);
						goto out;
					}
				}
			}	
		}
		oobofs += mtd->oobsize - hweccbytes * eccsteps;
		page++;
		numpages--;

		/* Apply delay or wait for ready/busy pin 
		 * Do this before the AUTOINCR check, so no problems
		 * arise if a chip which does auto increment
		 * is marked as NOAUTOINCR by the board driver.
		 * Do this also before returning, so the chip is
		 * ready for the next command.
		*/
		if (!this->dev_ready) 
			udelay (this->chip_delay);
		else
			while (!this->dev_ready(mtd));	

		/* All done, return happy */
		if (!numpages)
			return 0;
		
			
		/* Check, if the chip supports auto page increment */ 
		if (!NAND_CANAUTOINCR(this))
			this->cmdfunc (mtd, NAND_CMD_READ0, 0x00, page);
	}
	/* 
	 * Terminate the read command. We come here in case of an error
	 * So we must issue a reset command.
	 */
out:	 
	this->cmdfunc (mtd, NAND_CMD_RESET, -1, -1);
	return res;
}
#endif

/**
 * nand_read - [MTD Interface] MTD compability function for nand_read_ecc
 * @mtd:	MTD device structure
 * @from:	offset to read from
 * @len:	number of bytes to read
 * @retlen:	pointer to variable to store the number of read bytes
 * @buf:	the databuffer to put data
 *
 * This function simply calls nand_read_ecc with oob buffer and oobsel = NULL
*/
static int nand_read (struct mtd_info *mtd, loff_t from, size_t len, size_t * retlen, u_char * buf)
{
	return nand_read_ecc (mtd, from, len, retlen, buf, NULL, NULL);
}			   


/**
 * nand_read_ecc - [MTD Interface] Read data with ECC
 * @mtd:	MTD device structure
 * @from:	offset to read from
 * @len:	number of bytes to read
 * @retlen:	pointer to variable to store the number of read bytes
 * @buf:	the databuffer to put data
 * @oob_buf:	filesystem supplied oob data buffer
 * @oobsel:	oob selection structure
 *
 * NAND read with ECC
 */
static int nand_read_ecc (struct mtd_info *mtd, loff_t from, size_t len,
			  size_t * retlen, u_char * buf, u_char * oob_buf, struct nand_oobinfo *oobsel)
{
	int i, j, col, realpage, page, end, ecc, chipnr, sndcmd = 1;
	int read = 0, oob = 0, ecc_status = 0, ecc_failed = 0;
	struct nand_chip *this = mtd->priv;
	u_char *data_poi, *oob_data = oob_buf;
	u_char ecc_calc[32];
	u_char ecc_code[32];
        int eccmode, eccsteps;
	int	*oob_config, datidx;
	int	blockcheck = (1 << (this->phys_erase_shift - this->page_shift)) - 1;
	int	eccbytes;
	int	compareecc = 1;
	int	oobreadlen;


	DEBUG (MTD_DEBUG_LEVEL3, "nand_read_ecc: from = 0x%08x, len = %i\n", (unsigned int) from, (int) len);

	/* Do not allow reads past end of device */
	if ((from + len) > mtd->size) {
		DEBUG (MTD_DEBUG_LEVEL0, "nand_read_ecc: Attempt read beyond end of device\n");
		*retlen = 0;
		return -EINVAL;
	}

	/* Grab the lock and see if the device is available */
	nand_get_device (this, mtd ,FL_READING);

	/* use userspace supplied oobinfo, if zero */
	if (oobsel == NULL)
		oobsel = &mtd->oobinfo;
	
	/* Autoplace of oob data ? Use the default placement scheme */
	if (oobsel->useecc == MTD_NANDECC_AUTOPLACE)
		oobsel = this->autooob;
		
	eccmode = oobsel->useecc ? this->eccmode : NAND_ECC_NONE;
	oob_config = oobsel->eccpos;

	/* Select the NAND device */
	chipnr = (int)(from >> this->chip_shift);
	this->select_chip(mtd, chipnr);

	/* First we calculate the starting page */
	realpage = (int) (from >> this->page_shift);
	page = realpage & this->pagemask;

	/* Get raw starting column */
	col = from & (mtd->oobblock - 1);

	end = mtd->oobblock;
	ecc = this->eccsize;
	eccbytes = this->eccbytes;
	
	if ((eccmode == NAND_ECC_NONE) || (this->options & NAND_HWECC_SYNDROME))
		compareecc = 0;

	oobreadlen = mtd->oobsize;
	if (this->options & NAND_HWECC_SYNDROME) 
		oobreadlen -= oobsel->eccbytes;

	/* Loop until all data read */
	while (read < len) {
		
		int aligned = (!col && (len - read) >= end);
		/* 
		 * If the read is not page aligned, we have to read into data buffer
		 * due to ecc, else we read into return buffer direct
		 */
		if (aligned)
			data_poi = &buf[read];
		else 
			data_poi = this->data_buf;
		
		/* Check, if we have this page in the buffer 
		 *
		 * FIXME: Make it work when we must provide oob data too,
		 * check the usage of data_buf oob field
		 */
		if (realpage == this->pagebuf && !oob_buf) {
			/* aligned read ? */
			if (aligned)
				memcpy (data_poi, this->data_buf, end);
			goto readdata;
		}

		/* Check, if we must send the read command */
		if (sndcmd) {
			this->cmdfunc (mtd, NAND_CMD_READ0, 0x00, page);
			sndcmd = 0;
		}	

		/* get oob area, if we have no oob buffer from fs-driver */
		if (!oob_buf || oobsel->useecc == MTD_NANDECC_AUTOPLACE ||
			oobsel->useecc == MTD_NANDECC_AUTOPL_USR)
			oob_data = &this->data_buf[end];

		eccsteps = this->eccsteps;
		
		switch (eccmode) {
		case NAND_ECC_NONE: {	/* No ECC, Read in a page */
/* XXX U-BOOT XXX */
#if 0
			static unsigned long lastwhinge = 0;
			if ((lastwhinge / HZ) != (jiffies / HZ)) {
				printk (KERN_WARNING "Reading data from NAND FLASH without ECC is not recommended\n");
				lastwhinge = jiffies;
			}
#else
			puts("Reading data from NAND FLASH without ECC is not recommended\n");
#endif
			this->read_buf(mtd, data_poi, end);
			break;
		}
			
		case NAND_ECC_SOFT:	/* Software ECC 3/256: Read in a page + oob data */
			this->read_buf(mtd, data_poi, end);
			for (i = 0, datidx = 0; eccsteps; eccsteps--, i+=3, datidx += ecc) 
				this->calculate_ecc(mtd, &data_poi[datidx], &ecc_calc[i]);
			break;	

		default:
			for (i = 0, datidx = 0; eccsteps; eccsteps--, i+=eccbytes, datidx += ecc) {
				this->enable_hwecc(mtd, NAND_ECC_READ);
				this->read_buf(mtd, &data_poi[datidx], ecc);

				/* HW ecc with syndrome calculation must read the
				 * syndrome from flash immidiately after the data */
				if (!compareecc) {
					/* Some hw ecc generators need to know when the
					 * syndrome is read from flash */
					this->enable_hwecc(mtd, NAND_ECC_READSYN);
					this->read_buf(mtd, &oob_data[i], eccbytes);
					/* We calc error correction directly, it checks the hw
					 * generator for an error, reads back the syndrome and
					 * does the error correction on the fly */
					if (this->correct_data(mtd, &data_poi[datidx], &oob_data[i], &ecc_code[i]) == -1) {
						DEBUG (MTD_DEBUG_LEVEL0, "nand_read_ecc: " 
							"Failed ECC read, page 0x%08x on chip %d\n", page, chipnr);
						ecc_failed++;
					}
				} else {
					this->calculate_ecc(mtd, &data_poi[datidx], &ecc_calc[i]);
				}	
			}
			break;						
		}

		/* read oobdata */
		this->read_buf(mtd, &oob_data[mtd->oobsize - oobreadlen], oobreadlen);

		/* Skip ECC check, if not requested (ECC_NONE or HW_ECC with syndromes) */
		if (!compareecc)
			goto readoob;	
		
		/* Pick the ECC bytes out of the oob data */
		for (j = 0; j < oobsel->eccbytes; j++)
			ecc_code[j] = oob_data[oob_config[j]];

		/* correct data, if neccecary */
		for (i = 0, j = 0, datidx = 0; i < this->eccsteps; i++, datidx += ecc) {
			ecc_status = this->correct_data(mtd, &data_poi[datidx], &ecc_code[j], &ecc_calc[j]);
			
			/* Get next chunk of ecc bytes */
			j += eccbytes;
			
			/* Check, if we have a fs supplied oob-buffer, 
			 * This is the legacy mode. Used by YAFFS1
			 * Should go away some day
			 */
			if (oob_buf && oobsel->useecc == MTD_NANDECC_PLACE) { 
				int *p = (int *)(&oob_data[mtd->oobsize]);
				p[i] = ecc_status;
			}
			
			if (ecc_status == -1) {	
				DEBUG (MTD_DEBUG_LEVEL0, "nand_read_ecc: " "Failed ECC read, page 0x%08x\n", page);
				ecc_failed++;
			}
		}		

	readoob:
		/* check, if we have a fs supplied oob-buffer */
		if (oob_buf) {
			/* without autoplace. Legacy mode used by YAFFS1 */
			switch(oobsel->useecc) {
			case MTD_NANDECC_AUTOPLACE:
			case MTD_NANDECC_AUTOPL_USR:
				/* Walk through the autoplace chunks */
				for (i = 0, j = 0; j < mtd->oobavail; i++) {
					int from = oobsel->oobfree[i][0];
					int num = oobsel->oobfree[i][1];
					memcpy(&oob_buf[oob], &oob_data[from], num);
					j+= num;
				}
				oob += mtd->oobavail;
				break;
			case MTD_NANDECC_PLACE:
				/* YAFFS1 legacy mode */
				oob_data += this->eccsteps * sizeof (int);
			default:
				oob_data += mtd->oobsize;
			}
		}
	readdata:
		/* Partial page read, transfer data into fs buffer */
		if (!aligned) { 
			for (j = col; j < end && read < len; j++)
				buf[read++] = data_poi[j];
			this->pagebuf = realpage;	
		} else		
			read += mtd->oobblock;

		/* Apply delay or wait for ready/busy pin 
		 * Do this before the AUTOINCR check, so no problems
		 * arise if a chip which does auto increment
		 * is marked as NOAUTOINCR by the board driver.
		*/
		if (!this->dev_ready) 
			udelay (this->chip_delay);
		else
			while (!this->dev_ready(mtd));	
			
		if (read == len)
			break;	

		/* For subsequent reads align to page boundary. */
		col = 0;
		/* Increment page address */
		realpage++;

		page = realpage & this->pagemask;
		/* Check, if we cross a chip boundary */
		if (!page) {
			chipnr++;
			this->select_chip(mtd, -1);
			this->select_chip(mtd, chipnr);
		}
		/* Check, if the chip supports auto page increment 
		 * or if we have hit a block boundary. 
		*/ 
		if (!NAND_CANAUTOINCR(this) || !(page & blockcheck))
			sndcmd = 1;				
	}

	/* Deselect and wake up anyone waiting on the device */
	nand_release_device(mtd);

	/*
	 * Return success, if no ECC failures, else -EBADMSG
	 * fs driver will take care of that, because
	 * retlen == desired len and result == -EBADMSG
	 */
	*retlen = read;
	return ecc_failed ? -EBADMSG : 0;
}

/**
 * nand_read_oob - [MTD Interface] NAND read out-of-band
 * @mtd:	MTD device structure
 * @from:	offset to read from
 * @len:	number of bytes to read
 * @retlen:	pointer to variable to store the number of read bytes
 * @buf:	the databuffer to put data
 *
 * NAND read out-of-band data from the spare area
 */
static int nand_read_oob (struct mtd_info *mtd, loff_t from, size_t len, size_t * retlen, u_char * buf)
{
	int i, col, page, chipnr;
	struct nand_chip *this = mtd->priv;
	int	blockcheck = (1 << (this->phys_erase_shift - this->page_shift)) - 1;

	DEBUG (MTD_DEBUG_LEVEL3, "nand_read_oob: from = 0x%08x, len = %i\n", (unsigned int) from, (int) len);

	/* Shift to get page */
	page = (int)(from >> this->page_shift);
	chipnr = (int)(from >> this->chip_shift);
	
	/* Mask to get column */
	col = from & (mtd->oobsize - 1);

	/* Initialize return length value */
	*retlen = 0;

	/* Do not allow reads past end of device */
	if ((from + len) > mtd->size) {
		DEBUG (MTD_DEBUG_LEVEL0, "nand_read_oob: Attempt read beyond end of device\n");
		*retlen = 0;
		return -EINVAL;
	}

	/* Grab the lock and see if the device is available */
	nand_get_device (this, mtd , FL_READING);

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

	/* Send the read command */
	this->cmdfunc (mtd, NAND_CMD_READOOB, col, page & this->pagemask);
	/* 
	 * Read the data, if we read more than one page
	 * oob data, let the device transfer the data !
	 */
	i = 0;
	while (i < len) {
		int thislen = mtd->oobsize - col;
		thislen = min_t(int, thislen, len);
		this->read_buf(mtd, &buf[i], thislen);
		i += thislen;
		
		/* Apply delay or wait for ready/busy pin 
		 * Do this before the AUTOINCR check, so no problems
		 * arise if a chip which does auto increment
		 * is marked as NOAUTOINCR by the board driver.
		*/
		if (!this->dev_ready) 
			udelay (this->chip_delay);
		else
			while (!this->dev_ready(mtd));	

		/* Read more ? */
		if (i < len) {
			page++;
			col = 0;

			/* Check, if we cross a chip boundary */
			if (!(page & this->pagemask)) {
				chipnr++;
				this->select_chip(mtd, -1);
				this->select_chip(mtd, chipnr);
			}
				
			/* Check, if the chip supports auto page increment 
			 * or if we have hit a block boundary. 
			*/ 
			if (!NAND_CANAUTOINCR(this) || !(page & blockcheck)) {
				/* For subsequent page reads set offset to 0 */
			        this->cmdfunc (mtd, NAND_CMD_READOOB, 0x0, page & this->pagemask);
			}
		}
	}

	/* Deselect and wake up anyone waiting on the device */
	nand_release_device(mtd);

	/* Return happy */
	*retlen = len;
	return 0;
}

/**
 * nand_read_raw - [GENERIC] Read raw data including oob into buffer
 * @mtd:	MTD device structure
 * @buf:	temporary buffer
 * @from:	offset to read from
 * @len:	number of bytes to read
 * @ooblen:	number of oob data bytes to read
 *
 * Read raw data including oob into buffer
 */
int nand_read_raw (struct mtd_info *mtd, uint8_t *buf, loff_t from, size_t len, size_t ooblen)
{
	struct nand_chip *this = mtd->priv;
	int page = (int) (from >> this->page_shift);
	int chip = (int) (from >> this->chip_shift);
	int sndcmd = 1;
	int cnt = 0;
	int pagesize = mtd->oobblock + mtd->oobsize;
	int	blockcheck = (1 << (this->phys_erase_shift - this->page_shift)) - 1;

	/* Do not allow reads past end of device */
	if ((from + len) > mtd->size) {
		DEBUG (MTD_DEBUG_LEVEL0, "nand_read_raw: Attempt read beyond end of device\n");
		return -EINVAL;
	}

	/* Grab the lock and see if the device is available */
	nand_get_device (this, mtd , FL_READING);

	this->select_chip (mtd, chip);
	
	/* Add requested oob length */
	len += ooblen;
	
	while (len) {
		if (sndcmd)
			this->cmdfunc (mtd, NAND_CMD_READ0, 0, page & this->pagemask);
		sndcmd = 0;	

		this->read_buf (mtd, &buf[cnt], pagesize);

		len -= pagesize;
		cnt += pagesize;
		page++;
		
		if (!this->dev_ready) 
			udelay (this->chip_delay);
		else
			while (!this->dev_ready(mtd));	
			
		/* Check, if the chip supports auto page increment */ 
		if (!NAND_CANAUTOINCR(this) || !(page & blockcheck))
			sndcmd = 1;
	}

	/* Deselect and wake up anyone waiting on the device */
	nand_release_device(mtd);
	return 0;
}


/** 
 * nand_prepare_oobbuf - [GENERIC] Prepare the out of band buffer 
 * @mtd:	MTD device structure
 * @fsbuf:	buffer given by fs driver
 * @oobsel:	out of band selection structre
 * @autoplace:	1 = place given buffer into the oob bytes
 * @numpages:	number of pages to prepare
 *
 * Return:
 * 1. Filesystem buffer available and autoplacement is off,
 *    return filesystem buffer
 * 2. No filesystem buffer or autoplace is off, return internal
 *    buffer
 * 3. Filesystem buffer is given and autoplace selected
 *    put data from fs buffer into internal buffer and
 *    retrun internal buffer
 *
 * Note: The internal buffer is filled with 0xff. This must
 * be done only once, when no autoplacement happens
 * Autoplacement sets the buffer dirty flag, which
 * forces the 0xff fill before using the buffer again.
 *
*/
static u_char * nand_prepare_oobbuf (struct mtd_info *mtd, u_char *fsbuf, struct nand_oobinfo *oobsel,
		int autoplace, int numpages)
{
	struct nand_chip *this = mtd->priv;
	int i, len, ofs;

	/* Zero copy fs supplied buffer */
	if (fsbuf && !autoplace) 
		return fsbuf;

	/* Check, if the buffer must be filled with ff again */
	if (this->oobdirty) {	
		memset (this->oob_buf, 0xff, 
			mtd->oobsize << (this->phys_erase_shift - this->page_shift));
		this->oobdirty = 0;
	}	
	
	/* If we have no autoplacement or no fs buffer use the internal one */
	if (!autoplace || !fsbuf)
		return this->oob_buf;
	
	/* Walk through the pages and place the data */
	this->oobdirty = 1;
	ofs = 0;
	while (numpages--) {
		for (i = 0, len = 0; len < mtd->oobavail; i++) {
			int to = ofs + oobsel->oobfree[i][0];
			int num = oobsel->oobfree[i][1];
			memcpy (&this->oob_buf[to], fsbuf, num);
			len += num;
			fsbuf += num;
		}
		ofs += mtd->oobavail;
	}
	return this->oob_buf;
}

#define NOTALIGNED(x) (x & (mtd->oobblock-1)) != 0

/**
 * nand_write - [MTD Interface] compability function for nand_write_ecc
 * @mtd:	MTD device structure
 * @to:		offset to write to
 * @len:	number of bytes to write
 * @retlen:	pointer to variable to store the number of written bytes
 * @buf:	the data to write
 *
 * This function simply calls nand_write_ecc with oob buffer and oobsel = NULL
 *
*/
static int nand_write (struct mtd_info *mtd, loff_t to, size_t len, size_t * retlen, const u_char * buf)
{
	return (nand_write_ecc (mtd, to, len, retlen, buf, NULL, NULL));
}
			   
/**
 * nand_write_ecc - [MTD Interface] NAND write with ECC
 * @mtd:	MTD device structure
 * @to:		offset to write to
 * @len:	number of bytes to write
 * @retlen:	pointer to variable to store the number of written bytes
 * @buf:	the data to write
 * @eccbuf:	filesystem supplied oob data buffer
 * @oobsel:	oob selection structure
 *
 * NAND write with ECC
 */
static int nand_write_ecc (struct mtd_info *mtd, loff_t to, size_t len,
			   size_t * retlen, const u_char * buf, u_char * eccbuf, struct nand_oobinfo *oobsel)
{
	int startpage, page, ret = -EIO, oob = 0, written = 0, chipnr;
	int autoplace = 0, numpages, totalpages;
	struct nand_chip *this = mtd->priv;
	u_char *oobbuf, *bufstart;
	int	ppblock = (1 << (this->phys_erase_shift - this->page_shift));

	DEBUG (MTD_DEBUG_LEVEL3, "nand_write_ecc: to = 0x%08x, len = %i\n", (unsigned int) to, (int) len);

	/* Initialize retlen, in case of early exit */
	*retlen = 0;

	/* Do not allow write past end of device */
	if ((to + len) > mtd->size) {
		DEBUG (MTD_DEBUG_LEVEL0, "nand_write_ecc: Attempt to write past end of page\n");
		return -EINVAL;
	}

	/* reject writes, which are not page aligned */	
	if (NOTALIGNED (to) || NOTALIGNED(len)) {
		printk (KERN_NOTICE "nand_write_ecc: Attempt to write not page aligned data\n");
		return -EINVAL;
	}

	/* Grab the lock and see if the device is available */
	nand_get_device (this, mtd, FL_WRITING);

	/* Calculate chipnr */
	chipnr = (int)(to >> this->chip_shift);
	/* Select the NAND device */
	this->select_chip(mtd, chipnr);

	/* Check, if it is write protected */
	if (nand_check_wp(mtd))
		goto out;

	/* if oobsel is NULL, use chip defaults */
	if (oobsel == NULL) 
		oobsel = &mtd->oobinfo;		
		
	/* Autoplace of oob data ? Use the default placement scheme */
	if (oobsel->useecc == MTD_NANDECC_AUTOPLACE) {
		oobsel = this->autooob;
		autoplace = 1;
	}	
	if (oobsel->useecc == MTD_NANDECC_AUTOPL_USR)
		autoplace = 1;

	/* Setup variables and oob buffer */
	totalpages = len >> this->page_shift;
	page = (int) (to >> this->page_shift);
	/* Invalidate the page cache, if we write to the cached page */
	if (page <= this->pagebuf && this->pagebuf < (page + totalpages))  
		this->pagebuf = -1;
	
	/* Set it relative to chip */
	page &= this->pagemask;
	startpage = page;
	/* Calc number of pages we can write in one go */
	numpages = min (ppblock - (startpage  & (ppblock - 1)), totalpages);
	oobbuf = nand_prepare_oobbuf (mtd, eccbuf, oobsel, autoplace, numpages);
	bufstart = (u_char *)buf;

	/* Loop until all data is written */
	while (written < len) {

		this->data_poi = (u_char*) &buf[written];
		/* Write one page. If this is the last page to write
		 * or the last page in this block, then use the
		 * real pageprogram command, else select cached programming
		 * if supported by the chip.
		 */
		ret = nand_write_page (mtd, this, page, &oobbuf[oob], oobsel, (--numpages > 0));
		if (ret) {
			DEBUG (MTD_DEBUG_LEVEL0, "nand_write_ecc: write_page failed %d\n", ret);
			goto out;
		}	
		/* Next oob page */
		oob += mtd->oobsize;
		/* Update written bytes count */
		written += mtd->oobblock;
		if (written == len) 
			goto cmp;
		
		/* Increment page address */
		page++;

		/* Have we hit a block boundary ? Then we have to verify and
		 * if verify is ok, we have to setup the oob buffer for
		 * the next pages.
		*/
		if (!(page & (ppblock - 1))){
			int ofs;
			this->data_poi = bufstart;
			ret = nand_verify_pages (mtd, this, startpage, 
				page - startpage,
				oobbuf, oobsel, chipnr, (eccbuf != NULL));
			if (ret) {
				DEBUG (MTD_DEBUG_LEVEL0, "nand_write_ecc: verify_pages failed %d\n", ret);
				goto out;
			}	
			*retlen = written;

			ofs = autoplace ? mtd->oobavail : mtd->oobsize;
			if (eccbuf)
				eccbuf += (page - startpage) * ofs;
			totalpages -= page - startpage;
			numpages = min (totalpages, ppblock);
			page &= this->pagemask;
			startpage = page;
			oobbuf = nand_prepare_oobbuf (mtd, eccbuf, oobsel, 
					autoplace, numpages);
			/* Check, if we cross a chip boundary */
			if (!page) {
				chipnr++;
				this->select_chip(mtd, -1);
				this->select_chip(mtd, chipnr);
			}
		}
	}
	/* Verify the remaining pages */
cmp:
	this->data_poi = bufstart;
 	ret = nand_verify_pages (mtd, this, startpage, totalpages,
		oobbuf, oobsel, chipnr, (eccbuf != NULL));
	if (!ret)
		*retlen = written;
	else	
		DEBUG (MTD_DEBUG_LEVEL0, "nand_write_ecc: verify_pages failed %d\n", ret);

out:
	/* Deselect and wake up anyone waiting on the device */
	nand_release_device(mtd);

	return ret;
}


/**
 * nand_write_oob - [MTD Interface] NAND write out-of-band
 * @mtd:	MTD device structure
 * @to:		offset to write to
 * @len:	number of bytes to write
 * @retlen:	pointer to variable to store the number of written bytes
 * @buf:	the data to write
 *
 * NAND write out-of-band
 */
static int nand_write_oob (struct mtd_info *mtd, loff_t to, size_t len, size_t * retlen, const u_char * buf)
{
	int column, page, status, ret = -EIO, chipnr;
	struct nand_chip *this = mtd->priv;

	DEBUG (MTD_DEBUG_LEVEL3, "nand_write_oob: to = 0x%08x, len = %i\n", (unsigned int) to, (int) len);

	/* Shift to get page */
	page = (int) (to >> this->page_shift);
	chipnr = (int) (to >> this->chip_shift);

	/* Mask to get column */
	column = to & (mtd->oobsize - 1);

	/* Initialize return length value */
	*retlen = 0;

	/* Do not allow write past end of page */
	if ((column + len) > mtd->oobsize) {
		DEBUG (MTD_DEBUG_LEVEL0, "nand_write_oob: Attempt to write past end of page\n");
		return -EINVAL;
	}

	/* Grab the lock and see if the device is available */
	nand_get_device (this, mtd, FL_WRITING);

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

	/* Reset the chip. Some chips (like the Toshiba TC5832DC found
	   in one of my DiskOnChip 2000 test units) will clear the whole
	   data page too if we don't do this. I have no clue why, but
	   I seem to have 'fixed' it in the doc2000 driver in
	   August 1999.  dwmw2. */
	this->cmdfunc(mtd, NAND_CMD_RESET, -1, -1);

	/* Check, if it is write protected */
	if (nand_check_wp(mtd))
		goto out;
	
	/* Invalidate the page cache, if we write to the cached page */
	if (page == this->pagebuf)
		this->pagebuf = -1;

	if (NAND_MUST_PAD(this)) {
		/* Write out desired data */
		this->cmdfunc (mtd, NAND_CMD_SEQIN, mtd->oobblock, page & this->pagemask);
		/* prepad 0xff for partial programming */
		this->write_buf(mtd, ffchars, column);
		/* write data */
		this->write_buf(mtd, buf, len);
		/* postpad 0xff for partial programming */
		this->write_buf(mtd, ffchars, mtd->oobsize - (len+column));
	} else {
		/* Write out desired data */
		this->cmdfunc (mtd, NAND_CMD_SEQIN, mtd->oobblock + column, page & this->pagemask);
		/* write data */
		this->write_buf(mtd, buf, len);
	}
	/* Send command to program the OOB data */
	this->cmdfunc (mtd, NAND_CMD_PAGEPROG, -1, -1);

	status = this->waitfunc (mtd, this, FL_WRITING);

	/* See if device thinks it succeeded */
	if (status & 0x01) {
		DEBUG (MTD_DEBUG_LEVEL0, "nand_write_oob: " "Failed write, page 0x%08x\n", page);
		ret = -EIO;
		goto out;
	}
	/* Return happy */
	*retlen = len;

#ifdef CONFIG_MTD_NAND_VERIFY_WRITE
	/* Send command to read back the data */
	this->cmdfunc (mtd, NAND_CMD_READOOB, column, page & this->pagemask);

	if (this->verify_buf(mtd, buf, len)) {
		DEBUG (MTD_DEBUG_LEVEL0, "nand_write_oob: " "Failed write verify, page 0x%08x\n", page);
		ret = -EIO;
		goto out;
	}
#endif
	ret = 0;
out:
	/* Deselect and wake up anyone waiting on the device */
	nand_release_device(mtd);

	return ret;
}

/* XXX U-BOOT XXX */
#if 0
/**
 * nand_writev - [MTD Interface] compabilty function for nand_writev_ecc
 * @mtd:	MTD device structure
 * @vecs:	the iovectors to write
 * @count:	number of vectors
 * @to:		offset to write to
 * @retlen:	pointer to variable to store the number of written bytes
 *
 * NAND write with kvec. This just calls the ecc function
 */
static int nand_writev (struct mtd_info *mtd, const struct kvec *vecs, unsigned long count, 
		loff_t to, size_t * retlen)
{
	return (nand_writev_ecc (mtd, vecs, count, to, retlen, NULL, NULL));	
}

/**
 * nand_writev_ecc - [MTD Interface] write with iovec with ecc
 * @mtd:	MTD device structure
 * @vecs:	the iovectors to write
 * @count:	number of vectors
 * @to:		offset to write to
 * @retlen:	pointer to variable to store the number of written bytes
 * @eccbuf:	filesystem supplied oob data buffer
 * @oobsel:	oob selection structure
 *
 * NAND write with iovec with ecc
 */
static int nand_writev_ecc (struct mtd_info *mtd, const struct kvec *vecs, unsigned long count, 
		loff_t to, size_t * retlen, u_char *eccbuf, struct nand_oobinfo *oobsel)
{
	int i, page, len, total_len, ret = -EIO, written = 0, chipnr;
	int oob, numpages, autoplace = 0, startpage;
	struct nand_chip *this = mtd->priv;
	int	ppblock = (1 << (this->phys_erase_shift - this->page_shift));
	u_char *oobbuf, *bufstart;

	/* Preset written len for early exit */
	*retlen = 0;

	/* Calculate total length of data */
	total_len = 0;
	for (i = 0; i < count; i++)
		total_len += (int) vecs[i].iov_len;

	DEBUG (MTD_DEBUG_LEVEL3,
	       "nand_writev: to = 0x%08x, len = %i, count = %ld\n", (unsigned int) to, (unsigned int) total_len, count);

	/* Do not allow write past end of page */
	if ((to + total_len) > mtd->size) {
		DEBUG (MTD_DEBUG_LEVEL0, "nand_writev: Attempted write past end of device\n");
		return -EINVAL;
	}

	/* reject writes, which are not page aligned */	
	if (NOTALIGNED (to) || NOTALIGNED(total_len)) {
		printk (KERN_NOTICE "nand_write_ecc: Attempt to write not page aligned data\n");
		return -EINVAL;
	}

	/* Grab the lock and see if the device is available */
	nand_get_device (this, mtd, FL_WRITING);

	/* Get the current chip-nr */
	chipnr = (int) (to >> this->chip_shift);
	/* Select the NAND device */
	this->select_chip(mtd, chipnr);

	/* Check, if it is write protected */
	if (nand_check_wp(mtd))
		goto out;

	/* if oobsel is NULL, use chip defaults */
	if (oobsel == NULL) 
		oobsel = &mtd->oobinfo;		

	/* Autoplace of oob data ? Use the default placement scheme */
	if (oobsel->useecc == MTD_NANDECC_AUTOPLACE) {
		oobsel = this->autooob;
		autoplace = 1;
	}	
	if (oobsel->useecc == MTD_NANDECC_AUTOPL_USR)
		autoplace = 1;

	/* Setup start page */
	page = (int) (to >> this->page_shift);
	/* Invalidate the page cache, if we write to the cached page */
	if (page <= this->pagebuf && this->pagebuf < ((to + total_len) >> this->page_shift))  
		this->pagebuf = -1;

	startpage = page & this->pagemask;

	/* Loop until all kvec' data has been written */
	len = 0;
	while (count) {
		/* If the given tuple is >= pagesize then
		 * write it out from the iov
		 */
		if ((vecs->iov_len - len) >= mtd->oobblock) {
			/* Calc number of pages we can write
			 * out of this iov in one go */
			numpages = (vecs->iov_len - len) >> this->page_shift;
			/* Do not cross block boundaries */
			numpages = min (ppblock - (startpage & (ppblock - 1)), numpages);
			oobbuf = nand_prepare_oobbuf (mtd, NULL, oobsel, autoplace, numpages);
			bufstart = (u_char *)vecs->iov_base;
			bufstart += len;
			this->data_poi = bufstart;
			oob = 0;
			for (i = 1; i <= numpages; i++) {
				/* Write one page. If this is the last page to write
				 * then use the real pageprogram command, else select 
				 * cached programming if supported by the chip.
				 */
				ret = nand_write_page (mtd, this, page & this->pagemask, 
					&oobbuf[oob], oobsel, i != numpages);
				if (ret)
					goto out;
				this->data_poi += mtd->oobblock;
				len += mtd->oobblock;
				oob += mtd->oobsize;
				page++;
			}
			/* Check, if we have to switch to the next tuple */
			if (len >= (int) vecs->iov_len) {
				vecs++;
				len = 0;
				count--;
			}
		} else {
			/* We must use the internal buffer, read data out of each 
			 * tuple until we have a full page to write
			 */
			int cnt = 0;
			while (cnt < mtd->oobblock) {
				if (vecs->iov_base != NULL && vecs->iov_len) 
					this->data_buf[cnt++] = ((u_char *) vecs->iov_base)[len++];
				/* Check, if we have to switch to the next tuple */
				if (len >= (int) vecs->iov_len) {
					vecs++;
					len = 0;
					count--;
				}
			}
			this->pagebuf = page;	
			this->data_poi = this->data_buf;	
			bufstart = this->data_poi;
			numpages = 1;		
			oobbuf = nand_prepare_oobbuf (mtd, NULL, oobsel, autoplace, numpages);
			ret = nand_write_page (mtd, this, page & this->pagemask,
				oobbuf, oobsel, 0);
			if (ret)
				goto out;
			page++;
		}

		this->data_poi = bufstart;
		ret = nand_verify_pages (mtd, this, startpage, numpages, oobbuf, oobsel, chipnr, 0);
		if (ret)
			goto out;
			
		written += mtd->oobblock * numpages;
		/* All done ? */
		if (!count)
			break;

		startpage = page & this->pagemask;
		/* Check, if we cross a chip boundary */
		if (!startpage) {
			chipnr++;
			this->select_chip(mtd, -1);
			this->select_chip(mtd, chipnr);
		}
	}
	ret = 0;
out:
	/* Deselect and wake up anyone waiting on the device */
	nand_release_device(mtd);

	*retlen = written;
	return ret;