Linux-2.6.12-rc2

Initial git repository build. I'm not bothering with the full history,
even though we have it. We can create a separate "historical" git
archive of that later if we want to, and in the meantime it's about
3.2GB when imported into git - space that would just make the early
git days unnecessarily complicated, when we don't have a lot of good
infrastructure for it.

Let it rip!

1 files changed, 767 insertions, 0 deletions

diff --git a/drivers/mtd/nftlcore.c b/drivers/mtd/nftlcore.c
new file mode 100644
index 00000000000..b2014043634
--- /dev/null
+++ b/drivers/mtd/nftlcore.c
@@ -0,0 +1,767 @@
+/* Linux driver for NAND Flash Translation Layer      */
+/* (c) 1999 Machine Vision Holdings, Inc.             */
+/* Author: David Woodhouse <dwmw2@infradead.org>      */
+/* $Id: nftlcore.c,v 1.97 2004/11/16 18:28:59 dwmw2 Exp $ */
+
+/*
+  The contents of this file are distributed under the GNU General
+  Public License version 2. The author places no additional
+  restrictions of any kind on it.
+ */
+
+#define PRERELEASE
+
+#include <linux/config.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <asm/errno.h>
+#include <asm/io.h>
+#include <asm/uaccess.h>
+#include <linux/miscdevice.h>
+#include <linux/pci.h>
+#include <linux/delay.h>
+#include <linux/slab.h>
+#include <linux/sched.h>
+#include <linux/init.h>
+#include <linux/hdreg.h>
+
+#include <linux/kmod.h>
+#include <linux/mtd/mtd.h>
+#include <linux/mtd/nand.h>
+#include <linux/mtd/nftl.h>
+#include <linux/mtd/blktrans.h>
+
+/* maximum number of loops while examining next block, to have a
+   chance to detect consistency problems (they should never happen
+   because of the checks done in the mounting */
+
+#define MAX_LOOPS 10000
+
+
+static void nftl_add_mtd(struct mtd_blktrans_ops *tr, struct mtd_info *mtd)
+{
+	struct NFTLrecord *nftl;
+	unsigned long temp;
+
+	if (mtd->type != MTD_NANDFLASH)
+		return;
+	/* OK, this is moderately ugly.  But probably safe.  Alternatives? */
+	if (memcmp(mtd->name, "DiskOnChip", 10))
+		return;
+
+	if (!mtd->block_isbad) {
+		printk(KERN_ERR
+"NFTL no longer supports the old DiskOnChip drivers loaded via docprobe.\n"
+"Please use the new diskonchip driver under the NAND subsystem.\n");
+		return;
+	}
+
+	DEBUG(MTD_DEBUG_LEVEL1, "NFTL: add_mtd for %s\n", mtd->name);
+
+	nftl = kmalloc(sizeof(struct NFTLrecord), GFP_KERNEL);
+
+	if (!nftl) {
+		printk(KERN_WARNING "NFTL: out of memory for data structures\n");
+		return;
+	}
+	memset(nftl, 0, sizeof(*nftl));
+
+	nftl->mbd.mtd = mtd;
+	nftl->mbd.devnum = -1;
+	nftl->mbd.blksize = 512;
+	nftl->mbd.tr = tr;
+	memcpy(&nftl->oobinfo, &mtd->oobinfo, sizeof(struct nand_oobinfo));
+	nftl->oobinfo.useecc = MTD_NANDECC_PLACEONLY;
+
+        if (NFTL_mount(nftl) < 0) {
+		printk(KERN_WARNING "NFTL: could not mount device\n");
+		kfree(nftl);
+		return;
+        }
+
+	/* OK, it's a new one. Set up all the data structures. */
+
+	/* Calculate geometry */
+	nftl->cylinders = 1024;
+	nftl->heads = 16;
+
+	temp = nftl->cylinders * nftl->heads;
+	nftl->sectors = nftl->mbd.size / temp;
+	if (nftl->mbd.size % temp) {
+		nftl->sectors++;
+		temp = nftl->cylinders * nftl->sectors;
+		nftl->heads = nftl->mbd.size / temp;
+
+		if (nftl->mbd.size % temp) {
+			nftl->heads++;
+			temp = nftl->heads * nftl->sectors;
+			nftl->cylinders = nftl->mbd.size / temp;
+		}
+	}
+
+	if (nftl->mbd.size != nftl->heads * nftl->cylinders * nftl->sectors) {
+		/*
+		  Oh no we don't have 
+		   mbd.size == heads * cylinders * sectors
+		*/
+		printk(KERN_WARNING "NFTL: cannot calculate a geometry to "
+		       "match size of 0x%lx.\n", nftl->mbd.size);
+		printk(KERN_WARNING "NFTL: using C:%d H:%d S:%d "
+			"(== 0x%lx sects)\n",
+			nftl->cylinders, nftl->heads , nftl->sectors, 
+			(long)nftl->cylinders * (long)nftl->heads *
+			(long)nftl->sectors );
+	}
+
+	if (add_mtd_blktrans_dev(&nftl->mbd)) {
+		if (nftl->ReplUnitTable)
+			kfree(nftl->ReplUnitTable);
+		if (nftl->EUNtable)
+			kfree(nftl->EUNtable);
+		kfree(nftl);
+		return;
+	}
+#ifdef PSYCHO_DEBUG
+	printk(KERN_INFO "NFTL: Found new nftl%c\n", nftl->mbd.devnum + 'a');
+#endif
+}
+
+static void nftl_remove_dev(struct mtd_blktrans_dev *dev)
+{
+	struct NFTLrecord *nftl = (void *)dev;
+
+	DEBUG(MTD_DEBUG_LEVEL1, "NFTL: remove_dev (i=%d)\n", dev->devnum);
+
+	del_mtd_blktrans_dev(dev);
+	if (nftl->ReplUnitTable)
+		kfree(nftl->ReplUnitTable);
+	if (nftl->EUNtable)
+		kfree(nftl->EUNtable);
+	kfree(nftl);
+}
+
+#ifdef CONFIG_NFTL_RW
+
+/* Actual NFTL access routines */
+/* NFTL_findfreeblock: Find a free Erase Unit on the NFTL partition. This function is used
+ *	when the give Virtual Unit Chain
+ */
+static u16 NFTL_findfreeblock(struct NFTLrecord *nftl, int desperate )
+{
+	/* For a given Virtual Unit Chain: find or create a free block and
+	   add it to the chain */
+	/* We're passed the number of the last EUN in the chain, to save us from
+	   having to look it up again */
+	u16 pot = nftl->LastFreeEUN;
+	int silly = nftl->nb_blocks;
+
+	/* Normally, we force a fold to happen before we run out of free blocks completely */
+	if (!desperate && nftl->numfreeEUNs < 2) {
+		DEBUG(MTD_DEBUG_LEVEL1, "NFTL_findfreeblock: there are too few free EUNs\n");
+		return 0xffff;
+	}
+
+	/* Scan for a free block */
+	do {
+		if (nftl->ReplUnitTable[pot] == BLOCK_FREE) {
+			nftl->LastFreeEUN = pot;
+			nftl->numfreeEUNs--;
+			return pot;
+		}
+
+		/* This will probably point to the MediaHdr unit itself,
+		   right at the beginning of the partition. But that unit
+		   (and the backup unit too) should have the UCI set
+		   up so that it's not selected for overwriting */
+		if (++pot > nftl->lastEUN)
+			pot = le16_to_cpu(nftl->MediaHdr.FirstPhysicalEUN);
+
+		if (!silly--) {
+			printk("Argh! No free blocks found! LastFreeEUN = %d, "
+			       "FirstEUN = %d\n", nftl->LastFreeEUN, 
+			       le16_to_cpu(nftl->MediaHdr.FirstPhysicalEUN));
+			return 0xffff;
+		}
+	} while (pot != nftl->LastFreeEUN);
+
+	return 0xffff;
+}
+
+static u16 NFTL_foldchain (struct NFTLrecord *nftl, unsigned thisVUC, unsigned pendingblock )
+{
+	u16 BlockMap[MAX_SECTORS_PER_UNIT];
+	unsigned char BlockLastState[MAX_SECTORS_PER_UNIT];
+	unsigned char BlockFreeFound[MAX_SECTORS_PER_UNIT];
+	unsigned int thisEUN;
+	int block;
+	int silly;
+	unsigned int targetEUN;
+	struct nftl_oob oob;
+	int inplace = 1;
+        size_t retlen;
+
+	memset(BlockMap, 0xff, sizeof(BlockMap));
+	memset(BlockFreeFound, 0, sizeof(BlockFreeFound));
+
+	thisEUN = nftl->EUNtable[thisVUC];
+
+	if (thisEUN == BLOCK_NIL) {
+		printk(KERN_WARNING "Trying to fold non-existent "
+		       "Virtual Unit Chain %d!\n", thisVUC);
+		return BLOCK_NIL;
+	}
+	
+	/* Scan to find the Erase Unit which holds the actual data for each
+	   512-byte block within the Chain.
+	*/
+        silly = MAX_LOOPS;
+	targetEUN = BLOCK_NIL;
+	while (thisEUN <= nftl->lastEUN ) {
+                unsigned int status, foldmark;
+
+		targetEUN = thisEUN;
+		for (block = 0; block < nftl->EraseSize / 512; block ++) {
+			MTD_READOOB(nftl->mbd.mtd,
+				    (thisEUN * nftl->EraseSize) + (block * 512),
+				    16 , &retlen, (char *)&oob);
+			if (block == 2) {
+                                foldmark = oob.u.c.FoldMark | oob.u.c.FoldMark1;
+                                if (foldmark == FOLD_MARK_IN_PROGRESS) {
+                                        DEBUG(MTD_DEBUG_LEVEL1, 
+                                              "Write Inhibited on EUN %d\n", thisEUN);
+					inplace = 0;
+				} else {
+					/* There's no other reason not to do inplace,
+					   except ones that come later. So we don't need
+					   to preserve inplace */
+					inplace = 1;
+				}
+			}
+                        status = oob.b.Status | oob.b.Status1;
+			BlockLastState[block] = status;
+
+			switch(status) {
+			case SECTOR_FREE:
+				BlockFreeFound[block] = 1;
+				break;
+
+			case SECTOR_USED:
+				if (!BlockFreeFound[block])
+					BlockMap[block] = thisEUN;
+				else
+					printk(KERN_WARNING 
+					       "SECTOR_USED found after SECTOR_FREE "
+					       "in Virtual Unit Chain %d for block %d\n",
+					       thisVUC, block);
+				break;
+			case SECTOR_DELETED:
+				if (!BlockFreeFound[block])
+					BlockMap[block] = BLOCK_NIL;
+				else
+					printk(KERN_WARNING 
+					       "SECTOR_DELETED found after SECTOR_FREE "
+					       "in Virtual Unit Chain %d for block %d\n",
+					       thisVUC, block);
+				break;
+
+			case SECTOR_IGNORE:
+				break;
+			default:
+				printk("Unknown status for block %d in EUN %d: %x\n",
+				       block, thisEUN, status);
+			}
+		}
+
+		if (!silly--) {
+			printk(KERN_WARNING "Infinite loop in Virtual Unit Chain 0x%x\n",
+			       thisVUC);
+			return BLOCK_NIL;
+		}
+		
+		thisEUN = nftl->ReplUnitTable[thisEUN];
+	}
+
+	if (inplace) {
+		/* We're being asked to be a fold-in-place. Check
+		   that all blocks which actually have data associated
+		   with them (i.e. BlockMap[block] != BLOCK_NIL) are 
+		   either already present or SECTOR_FREE in the target
+		   block. If not, we're going to have to fold out-of-place
+		   anyway.
+		*/
+		for (block = 0; block < nftl->EraseSize / 512 ; block++) {
+			if (BlockLastState[block] != SECTOR_FREE &&
+			    BlockMap[block] != BLOCK_NIL &&
+			    BlockMap[block] != targetEUN) {
+				DEBUG(MTD_DEBUG_LEVEL1, "Setting inplace to 0. VUC %d, "
+				      "block %d was %x lastEUN, "
+				      "and is in EUN %d (%s) %d\n",
+				      thisVUC, block, BlockLastState[block],
+				      BlockMap[block], 
+				      BlockMap[block]== targetEUN ? "==" : "!=",
+				      targetEUN);
+				inplace = 0;
+				break;
+			}
+		}
+
+		if (pendingblock >= (thisVUC * (nftl->EraseSize / 512)) &&
+		    pendingblock < ((thisVUC + 1)* (nftl->EraseSize / 512)) &&
+		    BlockLastState[pendingblock - (thisVUC * (nftl->EraseSize / 512))] !=
+		    SECTOR_FREE) {
+			DEBUG(MTD_DEBUG_LEVEL1, "Pending write not free in EUN %d. "
+			      "Folding out of place.\n", targetEUN);
+			inplace = 0;
+		}
+	}
+	
+	if (!inplace) {
+		DEBUG(MTD_DEBUG_LEVEL1, "Cannot fold Virtual Unit Chain %d in place. "
+		      "Trying out-of-place\n", thisVUC);
+		/* We need to find a targetEUN to fold into. */
+		targetEUN = NFTL_findfreeblock(nftl, 1);
+		if (targetEUN == BLOCK_NIL) {
+			/* Ouch. Now we're screwed. We need to do a 
+			   fold-in-place of another chain to make room
+			   for this one. We need a better way of selecting
+			   which chain to fold, because makefreeblock will 
+			   only ask us to fold the same one again.
+			*/
+			printk(KERN_WARNING
+			       "NFTL_findfreeblock(desperate) returns 0xffff.\n");
+			return BLOCK_NIL;
+		}
+	} else {
+            /* We put a fold mark in the chain we are folding only if
+               we fold in place to help the mount check code. If we do
+               not fold in place, it is possible to find the valid
+               chain by selecting the longer one */
+            oob.u.c.FoldMark = oob.u.c.FoldMark1 = cpu_to_le16(FOLD_MARK_IN_PROGRESS);
+            oob.u.c.unused = 0xffffffff;
+            MTD_WRITEOOB(nftl->mbd.mtd, (nftl->EraseSize * targetEUN) + 2 * 512 + 8, 
+                         8, &retlen, (char *)&oob.u);
+        }
+
+	/* OK. We now know the location of every block in the Virtual Unit Chain,
+	   and the Erase Unit into which we are supposed to be copying.
+	   Go for it.
+	*/
+	DEBUG(MTD_DEBUG_LEVEL1,"Folding chain %d into unit %d\n", thisVUC, targetEUN);
+	for (block = 0; block < nftl->EraseSize / 512 ; block++) {
+		unsigned char movebuf[512];
+		int ret;
+
+		/* If it's in the target EUN already, or if it's pending write, do nothing */
+		if (BlockMap[block] == targetEUN ||
+		    (pendingblock == (thisVUC * (nftl->EraseSize / 512) + block))) {
+			continue;
+		}
+
+                /* copy only in non free block (free blocks can only
+                   happen in case of media errors or deleted blocks) */
+                if (BlockMap[block] == BLOCK_NIL)
+                        continue;
+                
+                ret = MTD_READ(nftl->mbd.mtd, (nftl->EraseSize * BlockMap[block]) + (block * 512),
+				  512, &retlen, movebuf); 
+                if (ret < 0) {
+                    ret = MTD_READ(nftl->mbd.mtd, (nftl->EraseSize * BlockMap[block])
+                                      + (block * 512), 512, &retlen,
+                                      movebuf); 
+                    if (ret != -EIO) 
+                        printk("Error went away on retry.\n");
+                }
+		memset(&oob, 0xff, sizeof(struct nftl_oob));
+		oob.b.Status = oob.b.Status1 = SECTOR_USED;
+                MTD_WRITEECC(nftl->mbd.mtd, (nftl->EraseSize * targetEUN) + (block * 512),
+                             512, &retlen, movebuf, (char *)&oob, &nftl->oobinfo);
+	}
+        
+        /* add the header so that it is now a valid chain */
+        oob.u.a.VirtUnitNum = oob.u.a.SpareVirtUnitNum
+                = cpu_to_le16(thisVUC);
+        oob.u.a.ReplUnitNum = oob.u.a.SpareReplUnitNum = 0xffff;
+        
+        MTD_WRITEOOB(nftl->mbd.mtd, (nftl->EraseSize * targetEUN) + 8, 
+                     8, &retlen, (char *)&oob.u);
+
+	/* OK. We've moved the whole lot into the new block. Now we have to free the original blocks. */
+
+	/* At this point, we have two different chains for this Virtual Unit, and no way to tell 
+	   them apart. If we crash now, we get confused. However, both contain the same data, so we
+	   shouldn't actually lose data in this case. It's just that when we load up on a medium which
+	   has duplicate chains, we need to free one of the chains because it's not necessary any more.
+	*/
+	thisEUN = nftl->EUNtable[thisVUC];
+	DEBUG(MTD_DEBUG_LEVEL1,"Want to erase\n");
+
+	/* For each block in the old chain (except the targetEUN of course), 
+	   free it and make it available for future use */
+	while (thisEUN <= nftl->lastEUN && thisEUN != targetEUN) {
+		unsigned int EUNtmp;
+
+                EUNtmp = nftl->ReplUnitTable[thisEUN];
+
+                if (NFTL_formatblock(nftl, thisEUN) < 0) {
+			/* could not erase : mark block as reserved
+			 */
+			nftl->ReplUnitTable[thisEUN] = BLOCK_RESERVED;
+                } else {
+			/* correctly erased : mark it as free */
+			nftl->ReplUnitTable[thisEUN] = BLOCK_FREE;
+			nftl->numfreeEUNs++;
+                }
+                thisEUN = EUNtmp;
+	}
+	
+	/* Make this the new start of chain for thisVUC */
+	nftl->ReplUnitTable[targetEUN] = BLOCK_NIL;
+	nftl->EUNtable[thisVUC] = targetEUN;
+
+	return targetEUN;
+}
+
+static u16 NFTL_makefreeblock( struct NFTLrecord *nftl , unsigned pendingblock)
+{
+	/* This is the part that needs some cleverness applied. 
+	   For now, I'm doing the minimum applicable to actually
+	   get the thing to work.
+	   Wear-levelling and other clever stuff needs to be implemented
+	   and we also need to do some assessment of the results when
+	   the system loses power half-way through the routine.
+	*/
+	u16 LongestChain = 0;
+	u16 ChainLength = 0, thislen;
+	u16 chain, EUN;
+
+	for (chain = 0; chain < le32_to_cpu(nftl->MediaHdr.FormattedSize) / nftl->EraseSize; chain++) {
+		EUN = nftl->EUNtable[chain];
+		thislen = 0;
+
+		while (EUN <= nftl->lastEUN) {
+			thislen++;
+			//printk("VUC %d reaches len %d with EUN %d\n", chain, thislen, EUN);
+			EUN = nftl->ReplUnitTable[EUN] & 0x7fff;
+			if (thislen > 0xff00) {
+				printk("Endless loop in Virtual Chain %d: Unit %x\n",
+				       chain, EUN);
+			}
+			if (thislen > 0xff10) {
+				/* Actually, don't return failure. Just ignore this chain and
+				   get on with it. */
+				thislen = 0;
+				break;
+			}
+		}
+
+		if (thislen > ChainLength) {
+			//printk("New longest chain is %d with length %d\n", chain, thislen);
+			ChainLength = thislen;
+			LongestChain = chain;
+		}
+	}
+
+	if (ChainLength < 2) {
+		printk(KERN_WARNING "No Virtual Unit Chains available for folding. "
+		       "Failing request\n");
+		return 0xffff;
+	}
+
+	return NFTL_foldchain (nftl, LongestChain, pendingblock);
+}
+
+/* NFTL_findwriteunit: Return the unit number into which we can write 
+                       for this block. Make it available if it isn't already
+*/
+static inline u16 NFTL_findwriteunit(struct NFTLrecord *nftl, unsigned block)
+{
+	u16 lastEUN;
+	u16 thisVUC = block / (nftl->EraseSize / 512);
+	unsigned int writeEUN;
+	unsigned long blockofs = (block * 512) & (nftl->EraseSize -1);
+	size_t retlen;
+	int silly, silly2 = 3;
+	struct nftl_oob oob;
+
+	do {
+		/* Scan the media to find a unit in the VUC which has
+		   a free space for the block in question.
+		*/
+
+		/* This condition catches the 0x[7f]fff cases, as well as 
+		   being a sanity check for past-end-of-media access
+		*/
+		lastEUN = BLOCK_NIL;
+		writeEUN = nftl->EUNtable[thisVUC];
+                silly = MAX_LOOPS;
+		while (writeEUN <= nftl->lastEUN) {
+			struct nftl_bci bci;
+			size_t retlen;
+                        unsigned int status;
+
+			lastEUN = writeEUN;
+
+			MTD_READOOB(nftl->mbd.mtd, (writeEUN * nftl->EraseSize) + blockofs,
+				    8, &retlen, (char *)&bci);
+			
+			DEBUG(MTD_DEBUG_LEVEL2, "Status of block %d in EUN %d is %x\n",
+			      block , writeEUN, le16_to_cpu(bci.Status));
+
+                        status = bci.Status | bci.Status1;
+			switch(status) {
+			case SECTOR_FREE:
+				return writeEUN;
+
+			case SECTOR_DELETED:
+			case SECTOR_USED:
+			case SECTOR_IGNORE:
+				break;
+			default:
+				// Invalid block. Don't use it any more. Must implement.
+				break;			
+			}
+			
+			if (!silly--) { 
+				printk(KERN_WARNING
+				       "Infinite loop in Virtual Unit Chain 0x%x\n",
+				       thisVUC);
+				return 0xffff;
+			}
+
+			/* Skip to next block in chain */
+			writeEUN = nftl->ReplUnitTable[writeEUN];
+		}
+
+		/* OK. We didn't find one in the existing chain, or there 
+		   is no existing chain. */
+
+		/* Try to find an already-free block */
+		writeEUN = NFTL_findfreeblock(nftl, 0);
+
+		if (writeEUN == BLOCK_NIL) {
+			/* That didn't work - there were no free blocks just
+			   waiting to be picked up. We're going to have to fold
+			   a chain to make room.
+			*/
+
+			/* First remember the start of this chain */
+			//u16 startEUN = nftl->EUNtable[thisVUC];
+			
+			//printk("Write to VirtualUnitChain %d, calling makefreeblock()\n", thisVUC);
+			writeEUN = NFTL_makefreeblock(nftl, 0xffff);
+
+			if (writeEUN == BLOCK_NIL) {
+				/* OK, we accept that the above comment is 
+				   lying - there may have been free blocks
+				   last time we called NFTL_findfreeblock(),
+				   but they are reserved for when we're
+				   desperate. Well, now we're desperate.
+				*/
+				DEBUG(MTD_DEBUG_LEVEL1, "Using desperate==1 to find free EUN to accommodate write to VUC %d\n", thisVUC);
+				writeEUN = NFTL_findfreeblock(nftl, 1);
+			}
+			if (writeEUN == BLOCK_NIL) {
+				/* Ouch. This should never happen - we should
+				   always be able to make some room somehow. 
+				   If we get here, we've allocated more storage 
+				   space than actual media, or our makefreeblock
+				   routine is missing something.
+				*/
+				printk(KERN_WARNING "Cannot make free space.\n");
+				return BLOCK_NIL;
+			}			
+			//printk("Restarting scan\n");
+			lastEUN = BLOCK_NIL;
+			continue;
+		}
+
+		/* We've found a free block. Insert it into the chain. */
+		
+		if (lastEUN != BLOCK_NIL) {
+                    thisVUC |= 0x8000; /* It's a replacement block */
+		} else {
+                    /* The first block in a new chain */
+                    nftl->EUNtable[thisVUC] = writeEUN;
+		}
+
+		/* set up the actual EUN we're writing into */
+		/* Both in our cache... */
+		nftl->ReplUnitTable[writeEUN] = BLOCK_NIL;
+
+		/* ... and on the flash itself */
+		MTD_READOOB(nftl->mbd.mtd, writeEUN * nftl->EraseSize + 8, 8,
+			    &retlen, (char *)&oob.u);
+
+		oob.u.a.VirtUnitNum = oob.u.a.SpareVirtUnitNum = cpu_to_le16(thisVUC);
+
+		MTD_WRITEOOB(nftl->mbd.mtd, writeEUN * nftl->EraseSize + 8, 8,
+                             &retlen, (char *)&oob.u);
+
+                /* we link the new block to the chain only after the
+                   block is ready. It avoids the case where the chain
+                   could point to a free block */
+                if (lastEUN != BLOCK_NIL) {
+			/* Both in our cache... */
+			nftl->ReplUnitTable[lastEUN] = writeEUN;
+			/* ... and on the flash itself */
+			MTD_READOOB(nftl->mbd.mtd, (lastEUN * nftl->EraseSize) + 8,
+				    8, &retlen, (char *)&oob.u);
+
+			oob.u.a.ReplUnitNum = oob.u.a.SpareReplUnitNum
+				= cpu_to_le16(writeEUN);
+
+			MTD_WRITEOOB(nftl->mbd.mtd, (lastEUN * nftl->EraseSize) + 8,
+				     8, &retlen, (char *)&oob.u);
+		}
+
+		return writeEUN;
+
+	} while (silly2--);
+
+	printk(KERN_WARNING "Error folding to make room for Virtual Unit Chain 0x%x\n",
+	       thisVUC);
+	return 0xffff;
+}
+
+static int nftl_writeblock(struct mtd_blktrans_dev *mbd, unsigned long block,
+			   char *buffer)
+{
+	struct NFTLrecord *nftl = (void *)mbd;
+	u16 writeEUN;
+	unsigned long blockofs = (block * 512) & (nftl->EraseSize - 1);
+	size_t retlen;
+	struct nftl_oob oob;
+
+	writeEUN = NFTL_findwriteunit(nftl, block);
+
+	if (writeEUN == BLOCK_NIL) {
+		printk(KERN_WARNING
+		       "NFTL_writeblock(): Cannot find block to write to\n");
+		/* If we _still_ haven't got a block to use, we're screwed */
+		return 1;
+	}
+
+	memset(&oob, 0xff, sizeof(struct nftl_oob));
+	oob.b.Status = oob.b.Status1 = SECTOR_USED;
+	MTD_WRITEECC(nftl->mbd.mtd, (writeEUN * nftl->EraseSize) + blockofs,
+		     512, &retlen, (char *)buffer, (char *)&oob, &nftl->oobinfo);
+        /* need to write SECTOR_USED flags since they are not written in mtd_writeecc */
+
+	return 0;
+}
+#endif /* CONFIG_NFTL_RW */
+
+static int nftl_readblock(struct mtd_blktrans_dev *mbd, unsigned long block,
+			  char *buffer)
+{
+	struct NFTLrecord *nftl = (void *)mbd;
+	u16 lastgoodEUN;
+	u16 thisEUN = nftl->EUNtable[block / (nftl->EraseSize / 512)];
+	unsigned long blockofs = (block * 512) & (nftl->EraseSize - 1);
+        unsigned int status;
+	int silly = MAX_LOOPS;
+        size_t retlen;
+        struct nftl_bci bci;
+
+	lastgoodEUN = BLOCK_NIL;
+
+        if (thisEUN != BLOCK_NIL) {
+		while (thisEUN < nftl->nb_blocks) {
+			if (MTD_READOOB(nftl->mbd.mtd, (thisEUN * nftl->EraseSize) + blockofs,
+					8, &retlen, (char *)&bci) < 0)
+				status = SECTOR_IGNORE;
+			else
+				status = bci.Status | bci.Status1;
+
+			switch (status) {
+			case SECTOR_FREE:
+				/* no modification of a sector should follow a free sector */
+				goto the_end;
+			case SECTOR_DELETED:
+				lastgoodEUN = BLOCK_NIL;
+				break;
+			case SECTOR_USED:
+				lastgoodEUN = thisEUN;
+				break;
+			case SECTOR_IGNORE:
+				break;
+			default:
+				printk("Unknown status for block %ld in EUN %d: %x\n",
+				       block, thisEUN, status);
+				break;
+			}
+
+			if (!silly--) {
+				printk(KERN_WARNING "Infinite loop in Virtual Unit Chain 0x%lx\n",
+				       block / (nftl->EraseSize / 512));
+				return 1;
+			}
+			thisEUN = nftl->ReplUnitTable[thisEUN];
+		}
+        }
+
+ the_end:
+	if (lastgoodEUN == BLOCK_NIL) {
+		/* the requested block is not on the media, return all 0x00 */
+		memset(buffer, 0, 512);
+	} else {
+		loff_t ptr = (lastgoodEUN * nftl->EraseSize) + blockofs;
+		size_t retlen;
+		if (MTD_READ(nftl->mbd.mtd, ptr, 512, &retlen, buffer))
+			return -EIO;
+	}
+	return 0;
+}
+
+static int nftl_getgeo(struct mtd_blktrans_dev *dev,  struct hd_geometry *geo)
+{
+	struct NFTLrecord *nftl = (void *)dev;
+
+	geo->heads = nftl->heads;
+	geo->sectors = nftl->sectors;
+	geo->cylinders = nftl->cylinders;
+
+	return 0;
+}
+
+/****************************************************************************
+ *
+ * Module stuff
+ *
+ ****************************************************************************/
+
+
+static struct mtd_blktrans_ops nftl_tr = {
+	.name		= "nftl",
+	.major		= NFTL_MAJOR,
+	.part_bits	= NFTL_PARTN_BITS,
+	.getgeo		= nftl_getgeo,
+	.readsect	= nftl_readblock,
+#ifdef CONFIG_NFTL_RW
+	.writesect	= nftl_writeblock,
+#endif
+	.add_mtd	= nftl_add_mtd,
+	.remove_dev	= nftl_remove_dev,
+	.owner		= THIS_MODULE,
+};
+
+extern char nftlmountrev[];
+
+static int __init init_nftl(void)
+{
+	printk(KERN_INFO "NFTL driver: nftlcore.c $Revision: 1.97 $, nftlmount.c %s\n", nftlmountrev);
+
+	return register_mtd_blktrans(&nftl_tr);
+}
+
+static void __exit cleanup_nftl(void)
+{
+	deregister_mtd_blktrans(&nftl_tr);
+}
+
+module_init(init_nftl);
+module_exit(cleanup_nftl);
+
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("David Woodhouse <dwmw2@infradead.org>, Fabrice Bellard <fabrice.bellard@netgem.com> et al.");
+MODULE_DESCRIPTION("Support code for NAND Flash Translation Layer, used on M-Systems DiskOnChip 2000 and Millennium");