[MTD] Rework the out of band handling completely

Hopefully the last iteration on this!

The handling of out of band data on NAND was accompanied by tons of fruitless
discussions and halfarsed patches to make it work for a particular
problem. Sufficiently annoyed by I all those "I know it better" mails and the
resonable amount of discarded "it solves my problem" patches, I finally decided
to go for the big rework. After removing the _ecc variants of mtd read/write
functions the solution to satisfy the various requirements was to refactor the
read/write _oob functions in mtd.

The major change is that read/write_oob now takes a pointer to an operation
descriptor structure "struct mtd_oob_ops".instead of having a function with at
least seven arguments.

read/write_oob which should probably renamed to a more descriptive name, can do
the following tasks:

- read/write out of band data
- read/write data content and out of band data
- read/write raw data content and out of band data (ecc disabled)

struct mtd_oob_ops has a mode field, which determines the oob handling mode.

Aside of the MTD_OOB_RAW mode, which is intended to be especially for
diagnostic purposes and some internal functions e.g. bad block table creation,
the other two modes are for mtd clients:

MTD_OOB_PLACE puts/gets the given oob data exactly to/from the place which is
described by the ooboffs and ooblen fields of the mtd_oob_ops strcuture. It's
up to the caller to make sure that the byte positions are not used by the ECC
placement algorithms.

MTD_OOB_AUTO puts/gets the given oob data automaticaly to/from the places in
the out of band area which are described by the oobfree tuples in the ecclayout
data structre which is associated to the devicee.

The decision whether data plus oob or oob only handling is done depends on the
setting of the datbuf member of the data structure. When datbuf == NULL then
the internal read/write_oob functions are selected, otherwise the read/write
data routines are invoked.

Tested on a few platforms with all variants. Please be aware of possible
regressions for your particular device / application scenario

Disclaimer: Any whining will be ignored from those who just contributed "hot
air blurb" and never sat down to tackle the underlying problem of the mess in
the NAND driver grown over time and the big chunk of work to fix up the
existing users. The problem was not the holiness of the existing MTD
interfaces. The problems was the lack of time to go for the big overhaul. It's
easy to add more mess to the existing one, but it takes alot of effort to go
for a real solution.

Improvements and bugfixes are welcome!

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

1 files changed, 139 insertions, 49 deletions

diff --git a/drivers/mtd/nand/nand_bbt.c b/drivers/mtd/nand/nand_bbt.c
index 40f9930..480c3cb 100644
--- a/drivers/mtd/nand/nand_bbt.c
+++ b/drivers/mtd/nand/nand_bbt.c
@@ -230,6 +230,42 @@ static int read_abs_bbt(struct mtd_info *mtd, uint8_t *buf, struct nand_bbt_desc
 	return 0;
 }
 
+/*
+ * Scan read raw data from flash
+ */
+static int scan_read_raw(struct mtd_info *mtd, uint8_t *buf, loff_t offs,
+			 size_t len)
+{
+	struct mtd_oob_ops ops;
+
+	ops.mode = MTD_OOB_RAW;
+	ops.ooboffs = 0;
+	ops.ooblen = mtd->oobsize;
+	ops.oobbuf = buf;
+	ops.datbuf = buf;
+	ops.len = len;
+
+	return mtd->read_oob(mtd, offs, &ops);
+}
+
+/*
+ * Scan write data with oob to flash
+ */
+static int scan_write_bbt(struct mtd_info *mtd, loff_t offs, size_t len,
+			  uint8_t *buf, uint8_t *oob)
+{
+	struct mtd_oob_ops ops;
+
+	ops.mode = MTD_OOB_PLACE;
+	ops.ooboffs = 0;
+	ops.ooblen = mtd->oobsize;
+	ops.datbuf = buf;
+	ops.oobbuf = oob;
+	ops.len = len;
+
+	return mtd->write_oob(mtd, offs, &ops);
+}
+
 /**
  * read_abs_bbts - [GENERIC] Read the bad block table(s) for all chips starting at a given page
  * @mtd:	MTD device structure
@@ -241,27 +277,85 @@ static int read_abs_bbt(struct mtd_info *mtd, uint8_t *buf, struct nand_bbt_desc
  * We assume that the bbt bits are in consecutive order.
  *
 */
-static int read_abs_bbts(struct mtd_info *mtd, uint8_t *buf, struct nand_bbt_descr *td, struct nand_bbt_descr *md)
+static int read_abs_bbts(struct mtd_info *mtd, uint8_t *buf,
+			 struct nand_bbt_descr *td, struct nand_bbt_descr *md)
 {
 	struct nand_chip *this = mtd->priv;
 
 	/* Read the primary version, if available */
 	if (td->options & NAND_BBT_VERSION) {
-		nand_read_raw(mtd, buf, td->pages[0] << this->page_shift, mtd->writesize, mtd->oobsize);
+		scan_read_raw(mtd, buf, td->pages[0] << this->page_shift,
+			      mtd->writesize);
 		td->version[0] = buf[mtd->writesize + td->veroffs];
-		printk(KERN_DEBUG "Bad block table at page %d, version 0x%02X\n", td->pages[0], td->version[0]);
+		printk(KERN_DEBUG "Bad block table at page %d, version 0x%02X\n",
+		       td->pages[0], td->version[0]);
 	}
 
 	/* Read the mirror version, if available */
 	if (md && (md->options & NAND_BBT_VERSION)) {
-		nand_read_raw(mtd, buf, md->pages[0] << this->page_shift, mtd->writesize, mtd->oobsize);
+		scan_read_raw(mtd, buf, md->pages[0] << this->page_shift,
+			      mtd->writesize);
 		md->version[0] = buf[mtd->writesize + md->veroffs];
-		printk(KERN_DEBUG "Bad block table at page %d, version 0x%02X\n", md->pages[0], md->version[0]);
+		printk(KERN_DEBUG "Bad block table at page %d, version 0x%02X\n",
+		       md->pages[0], md->version[0]);
 	}
-
 	return 1;
 }
 
+/*
+ * Scan a given block full
+ */
+static int scan_block_full(struct mtd_info *mtd, struct nand_bbt_descr *bd,
+			   loff_t offs, uint8_t *buf, size_t readlen,
+			   int scanlen, int len)
+{
+	int ret, j;
+
+	ret = scan_read_raw(mtd, buf, offs, readlen);
+	if (ret)
+		return ret;
+
+	for (j = 0; j < len; j++, buf += scanlen) {
+		if (check_pattern(buf, scanlen, mtd->writesize, bd))
+			return 1;
+	}
+	return 0;
+}
+
+/*
+ * Scan a given block partially
+ */
+static int scan_block_fast(struct mtd_info *mtd, struct nand_bbt_descr *bd,
+			   loff_t offs, uint8_t *buf, int len)
+{
+	struct mtd_oob_ops ops;
+	int j, ret;
+
+	ops.len = mtd->oobsize;
+	ops.ooblen = mtd->oobsize;
+	ops.oobbuf = buf;
+	ops.ooboffs = 0;
+	ops.datbuf = NULL;
+	ops.mode = MTD_OOB_PLACE;
+
+	for (j = 0; j < len; j++) {
+		/*
+		 * Read the full oob until read_oob is fixed to
+		 * handle single byte reads for 16 bit
+		 * buswidth
+		 */
+		ret = mtd->read_oob(mtd, offs, &ops);
+		if (ret)
+			return ret;
+
+		if (check_short_pattern(buf, bd))
+			return 1;
+
+		offs += mtd->writesize;
+	}
+	return 0;
+}
+
 /**
  * create_bbt - [GENERIC] Create a bad block table by scanning the device
  * @mtd:	MTD device structure
@@ -273,13 +367,14 @@ static int read_abs_bbts(struct mtd_info *mtd, uint8_t *buf, struct nand_bbt_des
  * 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)
+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, j, numblocks, len, scanlen;
+	int i, numblocks, len, scanlen;
 	int startblock;
 	loff_t from;
-	size_t readlen, ooblen;
+	size_t readlen;
 
 	printk(KERN_INFO "Scanning device for bad blocks\n");
 
@@ -294,18 +389,17 @@ static int create_bbt(struct mtd_info *mtd, uint8_t *buf, struct nand_bbt_descr
 
 	if (!(bd->options & NAND_BBT_SCANEMPTY)) {
 		/* We need only read few bytes from the OOB area */
-		scanlen = ooblen = 0;
+		scanlen = 0;
 		readlen = bd->len;
 	} else {
 		/* Full page content should be read */
 		scanlen = mtd->writesize + mtd->oobsize;
 		readlen = len * mtd->writesize;
-		ooblen = len * mtd->oobsize;
 	}
 
 	if (chip == -1) {
-		/* Note that numblocks is 2 * (real numblocks) here, see i+=2 below as it
-		 * makes shifting and masking less painful */
+		/* Note that numblocks is 2 * (real numblocks) here, see i+=2
+		 * below as it makes shifting and masking less painful */
 		numblocks = mtd->size >> (this->bbt_erase_shift - 1);
 		startblock = 0;
 		from = 0;
@@ -324,35 +418,21 @@ static int create_bbt(struct mtd_info *mtd, uint8_t *buf, struct nand_bbt_descr
 	for (i = startblock; i < numblocks;) {
 		int ret;
 
-		if (bd->options & NAND_BBT_SCANEMPTY)
-			if ((ret = nand_read_raw(mtd, buf, from, readlen, ooblen)))
-				return ret;
-
-		for (j = 0; j < len; j++) {
-			if (!(bd->options & NAND_BBT_SCANEMPTY)) {
-				size_t retlen;
-
-				/* Read the full oob until read_oob is fixed to
-				 * handle single byte reads for 16 bit buswidth */
-				ret = mtd->read_oob(mtd, from + j * mtd->writesize, mtd->oobsize, &retlen, buf);
-				if (ret)
-					return ret;
-
-				if (check_short_pattern(buf, bd)) {
-					this->bbt[i >> 3] |= 0x03 << (i & 0x6);
-					printk(KERN_WARNING "Bad eraseblock %d at 0x%08x\n",
-					       i >> 1, (unsigned int)from);
-					break;
-				}
-			} else {
-				if (check_pattern(&buf[j * scanlen], scanlen, mtd->writesize, bd)) {
-					this->bbt[i >> 3] |= 0x03 << (i & 0x6);
-					printk(KERN_WARNING "Bad eraseblock %d at 0x%08x\n",
-					       i >> 1, (unsigned int)from);
-					break;
-				}
-			}
+		if (bd->options & NAND_BBT_SCANALLPAGES)
+			ret = scan_block_full(mtd, bd, from, buf, readlen,
+					      scanlen, len);
+		else
+			ret = scan_block_fast(mtd, bd, from, buf, len);
+
+		if (ret < 0)
+			return ret;
+
+		if (ret) {
+			this->bbt[i >> 3] |= 0x03 << (i & 0x6);
+			printk(KERN_WARNING "Bad eraseblock %d at 0x%08x\n",
+			       i >> 1, (unsigned int)from);
 		}
+
 		i += 2;
 		from += (1 << this->bbt_erase_shift);
 	}
@@ -383,6 +463,7 @@ static int search_bbt(struct mtd_info *mtd, uint8_t *buf, struct nand_bbt_descr
 	int bits, startblock, block, dir;
 	int scanlen = mtd->writesize + mtd->oobsize;
 	int bbtblocks;
+	int blocktopage = this->bbt_erase_shift - this->page_shift;
 
 	/* Search direction top -> down ? */
 	if (td->options & NAND_BBT_LASTBLOCK) {
@@ -412,11 +493,14 @@ static int search_bbt(struct mtd_info *mtd, uint8_t *buf, struct nand_bbt_descr
 		td->pages[i] = -1;
 		/* Scan the maximum number of blocks */
 		for (block = 0; block < td->maxblocks; block++) {
+
 			int actblock = startblock + dir * block;
+			loff_t offs = actblock << this->bbt_erase_shift;
+
 			/* Read first page */
-			nand_read_raw(mtd, buf, actblock << this->bbt_erase_shift, mtd->writesize, mtd->oobsize);
+			scan_read_raw(mtd, buf, offs, mtd->writesize);
 			if (!check_pattern(buf, scanlen, mtd->writesize, td)) {
-				td->pages[i] = actblock << (this->bbt_erase_shift - this->page_shift);
+				td->pages[i] = actblock << blocktopage;
 				if (td->options & NAND_BBT_VERSION) {
 					td->version[i] = buf[mtd->writesize + td->veroffs];
 				}
@@ -481,8 +565,14 @@ static int write_bbt(struct mtd_info *mtd, uint8_t *buf,
 	int nrchips, bbtoffs, pageoffs, ooboffs;
 	uint8_t msk[4];
 	uint8_t rcode = td->reserved_block_code;
-	size_t retlen, len = 0, ooblen;
+	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_OOB_PLACE;
 
 	if (!rcode)
 		rcode = 0xff;
@@ -583,10 +673,10 @@ static int write_bbt(struct mtd_info *mtd, uint8_t *buf,
 				       "bad block table\n");
 			}
 			/* Read oob data */
-			ooblen = (len >> this->page_shift) * mtd->oobsize;
-			res = mtd->read_oob(mtd, to + mtd->writesize, ooblen,
-					    &retlen, &buf[len]);
-			if (res < 0 || retlen != ooblen)
+			ops.len = (len >> this->page_shift) * mtd->oobsize;
+			ops.oobbuf = &buf[len];
+			res = mtd->read_oob(mtd, to + mtd->writesize, &ops);
+			if (res < 0 || ops.retlen != ops.len)
 				goto outerr;
 
 			/* Calc the byte offset in the buffer */
@@ -635,7 +725,7 @@ static int write_bbt(struct mtd_info *mtd, uint8_t *buf,
 		if (res < 0)
 			goto outerr;
 
-		res = nand_write_raw(mtd, to, len, &retlen, buf, &buf[len]);
+		res = scan_write_bbt(mtd, to, len, buf, &buf[len]);
 		if (res < 0)
 			goto outerr;