Linux-2.6.12-rc2v2.6.12-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 000000000000..b2014043634f
--- /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");