Adding upstream version 6.1.76.upstream/6.1.76upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 944 insertions, 0 deletions

diff --git a/drivers/mtd/inftlcore.c b/drivers/mtd/inftlcore.c
new file mode 100644
index 000000000..58ca1c21e
--- /dev/null
+++ b/drivers/mtd/inftlcore.c
@@ -0,0 +1,944 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * inftlcore.c -- Linux driver for Inverse Flash Translation Layer (INFTL)
+ *
+ * Copyright © 2002, Greg Ungerer (gerg@snapgear.com)
+ *
+ * Based heavily on the nftlcore.c code which is:
+ * Copyright © 1999 Machine Vision Holdings, Inc.
+ * Copyright © 1999 David Woodhouse <dwmw2@infradead.org>
+ */
+
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/delay.h>
+#include <linux/slab.h>
+#include <linux/sched.h>
+#include <linux/init.h>
+#include <linux/kmod.h>
+#include <linux/hdreg.h>
+#include <linux/mtd/mtd.h>
+#include <linux/mtd/nftl.h>
+#include <linux/mtd/inftl.h>
+#include <linux/mtd/rawnand.h>
+#include <linux/uaccess.h>
+#include <asm/errno.h>
+#include <asm/io.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 inftl_add_mtd(struct mtd_blktrans_ops *tr, struct mtd_info *mtd)
+{
+	struct INFTLrecord *inftl;
+	unsigned long temp;
+
+	if (!mtd_type_is_nand(mtd) || mtd->size > UINT_MAX)
+		return;
+	/* OK, this is moderately ugly.  But probably safe.  Alternatives? */
+	if (memcmp(mtd->name, "DiskOnChip", 10))
+		return;
+
+	if (!mtd->_block_isbad) {
+		printk(KERN_ERR
+"INFTL no longer supports the old DiskOnChip drivers loaded via docprobe.\n"
+"Please use the new diskonchip driver under the NAND subsystem.\n");
+		return;
+	}
+
+	pr_debug("INFTL: add_mtd for %s\n", mtd->name);
+
+	inftl = kzalloc(sizeof(*inftl), GFP_KERNEL);
+
+	if (!inftl)
+		return;
+
+	inftl->mbd.mtd = mtd;
+	inftl->mbd.devnum = -1;
+
+	inftl->mbd.tr = tr;
+
+	if (INFTL_mount(inftl) < 0) {
+		printk(KERN_WARNING "INFTL: could not mount device\n");
+		kfree(inftl);
+		return;
+	}
+
+	/* OK, it's a new one. Set up all the data structures. */
+
+	/* Calculate geometry */
+	inftl->cylinders = 1024;
+	inftl->heads = 16;
+
+	temp = inftl->cylinders * inftl->heads;
+	inftl->sectors = inftl->mbd.size / temp;
+	if (inftl->mbd.size % temp) {
+		inftl->sectors++;
+		temp = inftl->cylinders * inftl->sectors;
+		inftl->heads = inftl->mbd.size / temp;
+
+		if (inftl->mbd.size % temp) {
+			inftl->heads++;
+			temp = inftl->heads * inftl->sectors;
+			inftl->cylinders = inftl->mbd.size / temp;
+		}
+	}
+
+	if (inftl->mbd.size != inftl->heads * inftl->cylinders * inftl->sectors) {
+		/*
+		  Oh no we don't have
+		   mbd.size == heads * cylinders * sectors
+		*/
+		printk(KERN_WARNING "INFTL: cannot calculate a geometry to "
+		       "match size of 0x%lx.\n", inftl->mbd.size);
+		printk(KERN_WARNING "INFTL: using C:%d H:%d S:%d "
+			"(== 0x%lx sects)\n",
+			inftl->cylinders, inftl->heads , inftl->sectors,
+			(long)inftl->cylinders * (long)inftl->heads *
+			(long)inftl->sectors );
+	}
+
+	if (add_mtd_blktrans_dev(&inftl->mbd)) {
+		kfree(inftl->PUtable);
+		kfree(inftl->VUtable);
+		kfree(inftl);
+		return;
+	}
+#ifdef PSYCHO_DEBUG
+	printk(KERN_INFO "INFTL: Found new inftl%c\n", inftl->mbd.devnum + 'a');
+#endif
+	return;
+}
+
+static void inftl_remove_dev(struct mtd_blktrans_dev *dev)
+{
+	struct INFTLrecord *inftl = (void *)dev;
+
+	pr_debug("INFTL: remove_dev (i=%d)\n", dev->devnum);
+
+	del_mtd_blktrans_dev(dev);
+
+	kfree(inftl->PUtable);
+	kfree(inftl->VUtable);
+}
+
+/*
+ * Actual INFTL access routines.
+ */
+
+/*
+ * Read oob data from flash
+ */
+int inftl_read_oob(struct mtd_info *mtd, loff_t offs, size_t len,
+		   size_t *retlen, uint8_t *buf)
+{
+	struct mtd_oob_ops ops = { };
+	int res;
+
+	ops.mode = MTD_OPS_PLACE_OOB;
+	ops.ooboffs = offs & (mtd->writesize - 1);
+	ops.ooblen = len;
+	ops.oobbuf = buf;
+	ops.datbuf = NULL;
+
+	res = mtd_read_oob(mtd, offs & ~(mtd->writesize - 1), &ops);
+	*retlen = ops.oobretlen;
+	return res;
+}
+
+/*
+ * Write oob data to flash
+ */
+int inftl_write_oob(struct mtd_info *mtd, loff_t offs, size_t len,
+		    size_t *retlen, uint8_t *buf)
+{
+	struct mtd_oob_ops ops = { };
+	int res;
+
+	ops.mode = MTD_OPS_PLACE_OOB;
+	ops.ooboffs = offs & (mtd->writesize - 1);
+	ops.ooblen = len;
+	ops.oobbuf = buf;
+	ops.datbuf = NULL;
+
+	res = mtd_write_oob(mtd, offs & ~(mtd->writesize - 1), &ops);
+	*retlen = ops.oobretlen;
+	return res;
+}
+
+/*
+ * Write data and oob to flash
+ */
+static int inftl_write(struct mtd_info *mtd, loff_t offs, size_t len,
+		       size_t *retlen, uint8_t *buf, uint8_t *oob)
+{
+	struct mtd_oob_ops ops = { };
+	int res;
+
+	ops.mode = MTD_OPS_PLACE_OOB;
+	ops.ooboffs = offs;
+	ops.ooblen = mtd->oobsize;
+	ops.oobbuf = oob;
+	ops.datbuf = buf;
+	ops.len = len;
+
+	res = mtd_write_oob(mtd, offs & ~(mtd->writesize - 1), &ops);
+	*retlen = ops.retlen;
+	return res;
+}
+
+/*
+ * INFTL_findfreeblock: Find a free Erase Unit on the INFTL partition.
+ *	This function is used when the give Virtual Unit Chain.
+ */
+static u16 INFTL_findfreeblock(struct INFTLrecord *inftl, int desperate)
+{
+	u16 pot = inftl->LastFreeEUN;
+	int silly = inftl->nb_blocks;
+
+	pr_debug("INFTL: INFTL_findfreeblock(inftl=%p,desperate=%d)\n",
+			inftl, desperate);
+
+	/*
+	 * Normally, we force a fold to happen before we run out of free
+	 * blocks completely.
+	 */
+	if (!desperate && inftl->numfreeEUNs < 2) {
+		pr_debug("INFTL: there are too few free EUNs (%d)\n",
+				inftl->numfreeEUNs);
+		return BLOCK_NIL;
+	}
+
+	/* Scan for a free block */
+	do {
+		if (inftl->PUtable[pot] == BLOCK_FREE) {
+			inftl->LastFreeEUN = pot;
+			return pot;
+		}
+
+		if (++pot > inftl->lastEUN)
+			pot = 0;
+
+		if (!silly--) {
+			printk(KERN_WARNING "INFTL: no free blocks found!  "
+				"EUN range = %d - %d\n", 0, inftl->LastFreeEUN);
+			return BLOCK_NIL;
+		}
+	} while (pot != inftl->LastFreeEUN);
+
+	return BLOCK_NIL;
+}
+
+static u16 INFTL_foldchain(struct INFTLrecord *inftl, unsigned thisVUC, unsigned pendingblock)
+{
+	u16 BlockMap[MAX_SECTORS_PER_UNIT];
+	unsigned char BlockDeleted[MAX_SECTORS_PER_UNIT];
+	unsigned int thisEUN, prevEUN, status;
+	struct mtd_info *mtd = inftl->mbd.mtd;
+	int block, silly;
+	unsigned int targetEUN;
+	struct inftl_oob oob;
+	size_t retlen;
+
+	pr_debug("INFTL: INFTL_foldchain(inftl=%p,thisVUC=%d,pending=%d)\n",
+			inftl, thisVUC, pendingblock);
+
+	memset(BlockMap, 0xff, sizeof(BlockMap));
+	memset(BlockDeleted, 0, sizeof(BlockDeleted));
+
+	thisEUN = targetEUN = inftl->VUtable[thisVUC];
+
+	if (thisEUN == BLOCK_NIL) {
+		printk(KERN_WARNING "INFTL: 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;
+	while (thisEUN < inftl->nb_blocks) {
+		for (block = 0; block < inftl->EraseSize/SECTORSIZE; block ++) {
+			if ((BlockMap[block] != BLOCK_NIL) ||
+			    BlockDeleted[block])
+				continue;
+
+			if (inftl_read_oob(mtd, (thisEUN * inftl->EraseSize)
+					   + (block * SECTORSIZE), 16, &retlen,
+					   (char *)&oob) < 0)
+				status = SECTOR_IGNORE;
+			else
+				status = oob.b.Status | oob.b.Status1;
+
+			switch(status) {
+			case SECTOR_FREE:
+			case SECTOR_IGNORE:
+				break;
+			case SECTOR_USED:
+				BlockMap[block] = thisEUN;
+				continue;
+			case SECTOR_DELETED:
+				BlockDeleted[block] = 1;
+				continue;
+			default:
+				printk(KERN_WARNING "INFTL: unknown status "
+					"for block %d in EUN %d: %x\n",
+					block, thisEUN, status);
+				break;
+			}
+		}
+
+		if (!silly--) {
+			printk(KERN_WARNING "INFTL: infinite loop in Virtual "
+				"Unit Chain 0x%x\n", thisVUC);
+			return BLOCK_NIL;
+		}
+
+		thisEUN = inftl->PUtable[thisEUN];
+	}
+
+	/*
+	 * 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.
+	 */
+	pr_debug("INFTL: folding chain %d into unit %d\n", thisVUC, targetEUN);
+
+	for (block = 0; block < inftl->EraseSize/SECTORSIZE ; block++) {
+		unsigned char movebuf[SECTORSIZE];
+		int ret;
+
+		/*
+		 * If it's in the target EUN already, or if it's pending write,
+		 * do nothing.
+		 */
+		if (BlockMap[block] == targetEUN || (pendingblock ==
+		    (thisVUC * (inftl->EraseSize / SECTORSIZE) + 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(mtd,
+			       (inftl->EraseSize * BlockMap[block]) + (block * SECTORSIZE),
+			       SECTORSIZE,
+			       &retlen,
+			       movebuf);
+		if (ret < 0 && !mtd_is_bitflip(ret)) {
+			ret = mtd_read(mtd,
+				       (inftl->EraseSize * BlockMap[block]) + (block * SECTORSIZE),
+				       SECTORSIZE,
+				       &retlen,
+				       movebuf);
+			if (ret != -EIO)
+				pr_debug("INFTL: error went away on retry?\n");
+		}
+		memset(&oob, 0xff, sizeof(struct inftl_oob));
+		oob.b.Status = oob.b.Status1 = SECTOR_USED;
+
+		inftl_write(inftl->mbd.mtd, (inftl->EraseSize * targetEUN) +
+			    (block * SECTORSIZE), SECTORSIZE, &retlen,
+			    movebuf, (char *)&oob);
+	}
+
+	/*
+	 * Newest unit in chain now contains data from _all_ older units.
+	 * So go through and erase each unit in chain, oldest first. (This
+	 * is important, by doing oldest first if we crash/reboot then it
+	 * it is relatively simple to clean up the mess).
+	 */
+	pr_debug("INFTL: want to erase virtual chain %d\n", thisVUC);
+
+	for (;;) {
+		/* Find oldest unit in chain. */
+		thisEUN = inftl->VUtable[thisVUC];
+		prevEUN = BLOCK_NIL;
+		while (inftl->PUtable[thisEUN] != BLOCK_NIL) {
+			prevEUN = thisEUN;
+			thisEUN = inftl->PUtable[thisEUN];
+		}
+
+		/* Check if we are all done */
+		if (thisEUN == targetEUN)
+			break;
+
+		/* Unlink the last block from the chain. */
+		inftl->PUtable[prevEUN] = BLOCK_NIL;
+
+		/* Now try to erase it. */
+		if (INFTL_formatblock(inftl, thisEUN) < 0) {
+			/*
+			 * Could not erase : mark block as reserved.
+			 */
+			inftl->PUtable[thisEUN] = BLOCK_RESERVED;
+		} else {
+			/* Correctly erased : mark it as free */
+			inftl->PUtable[thisEUN] = BLOCK_FREE;
+			inftl->numfreeEUNs++;
+		}
+	}
+
+	return targetEUN;
+}
+
+static u16 INFTL_makefreeblock(struct INFTLrecord *inftl, 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;
+
+	pr_debug("INFTL: INFTL_makefreeblock(inftl=%p,"
+		"pending=%d)\n", inftl, pendingblock);
+
+	for (chain = 0; chain < inftl->nb_blocks; chain++) {
+		EUN = inftl->VUtable[chain];
+		thislen = 0;
+
+		while (EUN <= inftl->lastEUN) {
+			thislen++;
+			EUN = inftl->PUtable[EUN];
+			if (thislen > 0xff00) {
+				printk(KERN_WARNING "INFTL: endless loop in "
+					"Virtual Chain %d: Unit %x\n",
+					chain, EUN);
+				/*
+				 * Actually, don't return failure.
+				 * Just ignore this chain and get on with it.
+				 */
+				thislen = 0;
+				break;
+			}
+		}
+
+		if (thislen > ChainLength) {
+			ChainLength = thislen;
+			LongestChain = chain;
+		}
+	}
+
+	if (ChainLength < 2) {
+		printk(KERN_WARNING "INFTL: no Virtual Unit Chains available "
+			"for folding. Failing request\n");
+		return BLOCK_NIL;
+	}
+
+	return INFTL_foldchain(inftl, LongestChain, pendingblock);
+}
+
+static int nrbits(unsigned int val, int bitcount)
+{
+	int i, total = 0;
+
+	for (i = 0; (i < bitcount); i++)
+		total += (((0x1 << i) & val) ? 1 : 0);
+	return total;
+}
+
+/*
+ * INFTL_findwriteunit: Return the unit number into which we can write
+ *                      for this block. Make it available if it isn't already.
+ */
+static inline u16 INFTL_findwriteunit(struct INFTLrecord *inftl, unsigned block)
+{
+	unsigned int thisVUC = block / (inftl->EraseSize / SECTORSIZE);
+	unsigned int thisEUN, writeEUN, prev_block, status;
+	unsigned long blockofs = (block * SECTORSIZE) & (inftl->EraseSize -1);
+	struct mtd_info *mtd = inftl->mbd.mtd;
+	struct inftl_oob oob;
+	struct inftl_bci bci;
+	unsigned char anac, nacs, parity;
+	size_t retlen;
+	int silly, silly2 = 3;
+
+	pr_debug("INFTL: INFTL_findwriteunit(inftl=%p,block=%d)\n",
+			inftl, block);
+
+	do {
+		/*
+		 * Scan the media to find a unit in the VUC which has
+		 * a free space for the block in question.
+		 */
+		writeEUN = BLOCK_NIL;
+		thisEUN = inftl->VUtable[thisVUC];
+		silly = MAX_LOOPS;
+
+		while (thisEUN <= inftl->lastEUN) {
+			inftl_read_oob(mtd, (thisEUN * inftl->EraseSize) +
+				       blockofs, 8, &retlen, (char *)&bci);
+
+			status = bci.Status | bci.Status1;
+			pr_debug("INFTL: status of block %d in EUN %d is %x\n",
+					block , writeEUN, status);
+
+			switch(status) {
+			case SECTOR_FREE:
+				writeEUN = thisEUN;
+				break;
+			case SECTOR_DELETED:
+			case SECTOR_USED:
+				/* Can't go any further */
+				goto hitused;
+			case SECTOR_IGNORE:
+				break;
+			default:
+				/*
+				 * Invalid block. Don't use it any more.
+				 * Must implement.
+				 */
+				break;
+			}
+
+			if (!silly--) {
+				printk(KERN_WARNING "INFTL: infinite loop in "
+					"Virtual Unit Chain 0x%x\n", thisVUC);
+				return BLOCK_NIL;
+			}
+
+			/* Skip to next block in chain */
+			thisEUN = inftl->PUtable[thisEUN];
+		}
+
+hitused:
+		if (writeEUN != BLOCK_NIL)
+			return writeEUN;
+
+
+		/*
+		 * OK. We didn't find one in the existing chain, or there
+		 * is no existing chain. Allocate a new one.
+		 */
+		writeEUN = INFTL_findfreeblock(inftl, 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.
+			 */
+			thisEUN = INFTL_makefreeblock(inftl, block);
+
+			/*
+			 * Hopefully we free something, lets try again.
+			 * This time we are desperate...
+			 */
+			pr_debug("INFTL: using desperate==1 to find free EUN "
+					"to accommodate write to VUC %d\n",
+					thisVUC);
+			writeEUN = INFTL_findfreeblock(inftl, 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 "INFTL: cannot make free "
+					"space.\n");
+#ifdef DEBUG
+				INFTL_dumptables(inftl);
+				INFTL_dumpVUchains(inftl);
+#endif
+				return BLOCK_NIL;
+			}
+		}
+
+		/*
+		 * Insert new block into virtual chain. Firstly update the
+		 * block headers in flash...
+		 */
+		anac = 0;
+		nacs = 0;
+		thisEUN = inftl->VUtable[thisVUC];
+		if (thisEUN != BLOCK_NIL) {
+			inftl_read_oob(mtd, thisEUN * inftl->EraseSize
+				       + 8, 8, &retlen, (char *)&oob.u);
+			anac = oob.u.a.ANAC + 1;
+			nacs = oob.u.a.NACs + 1;
+		}
+
+		prev_block = inftl->VUtable[thisVUC];
+		if (prev_block < inftl->nb_blocks)
+			prev_block -= inftl->firstEUN;
+
+		parity = (nrbits(thisVUC, 16) & 0x1) ? 0x1 : 0;
+		parity |= (nrbits(prev_block, 16) & 0x1) ? 0x2 : 0;
+		parity |= (nrbits(anac, 8) & 0x1) ? 0x4 : 0;
+		parity |= (nrbits(nacs, 8) & 0x1) ? 0x8 : 0;
+
+		oob.u.a.virtualUnitNo = cpu_to_le16(thisVUC);
+		oob.u.a.prevUnitNo = cpu_to_le16(prev_block);
+		oob.u.a.ANAC = anac;
+		oob.u.a.NACs = nacs;
+		oob.u.a.parityPerField = parity;
+		oob.u.a.discarded = 0xaa;
+
+		inftl_write_oob(mtd, writeEUN * inftl->EraseSize + 8, 8,
+				&retlen, (char *)&oob.u);
+
+		/* Also back up header... */
+		oob.u.b.virtualUnitNo = cpu_to_le16(thisVUC);
+		oob.u.b.prevUnitNo = cpu_to_le16(prev_block);
+		oob.u.b.ANAC = anac;
+		oob.u.b.NACs = nacs;
+		oob.u.b.parityPerField = parity;
+		oob.u.b.discarded = 0xaa;
+
+		inftl_write_oob(mtd, writeEUN * inftl->EraseSize +
+				SECTORSIZE * 4 + 8, 8, &retlen, (char *)&oob.u);
+
+		inftl->PUtable[writeEUN] = inftl->VUtable[thisVUC];
+		inftl->VUtable[thisVUC] = writeEUN;
+
+		inftl->numfreeEUNs--;
+		return writeEUN;
+
+	} while (silly2--);
+
+	printk(KERN_WARNING "INFTL: error folding to make room for Virtual "
+		"Unit Chain 0x%x\n", thisVUC);
+	return BLOCK_NIL;
+}
+
+/*
+ * Given a Virtual Unit Chain, see if it can be deleted, and if so do it.
+ */
+static void INFTL_trydeletechain(struct INFTLrecord *inftl, unsigned thisVUC)
+{
+	struct mtd_info *mtd = inftl->mbd.mtd;
+	unsigned char BlockUsed[MAX_SECTORS_PER_UNIT];
+	unsigned char BlockDeleted[MAX_SECTORS_PER_UNIT];
+	unsigned int thisEUN, status;
+	int block, silly;
+	struct inftl_bci bci;
+	size_t retlen;
+
+	pr_debug("INFTL: INFTL_trydeletechain(inftl=%p,"
+		"thisVUC=%d)\n", inftl, thisVUC);
+
+	memset(BlockUsed, 0, sizeof(BlockUsed));
+	memset(BlockDeleted, 0, sizeof(BlockDeleted));
+
+	thisEUN = inftl->VUtable[thisVUC];
+	if (thisEUN == BLOCK_NIL) {
+		printk(KERN_WARNING "INFTL: trying to delete non-existent "
+		       "Virtual Unit Chain %d!\n", thisVUC);
+		return;
+	}
+
+	/*
+	 * Scan through the Erase Units to determine whether any data is in
+	 * each of the 512-byte blocks within the Chain.
+	 */
+	silly = MAX_LOOPS;
+	while (thisEUN < inftl->nb_blocks) {
+		for (block = 0; block < inftl->EraseSize/SECTORSIZE; block++) {
+			if (BlockUsed[block] || BlockDeleted[block])
+				continue;
+
+			if (inftl_read_oob(mtd, (thisEUN * inftl->EraseSize)
+					   + (block * SECTORSIZE), 8 , &retlen,
+					  (char *)&bci) < 0)
+				status = SECTOR_IGNORE;
+			else
+				status = bci.Status | bci.Status1;
+
+			switch(status) {
+			case SECTOR_FREE:
+			case SECTOR_IGNORE:
+				break;
+			case SECTOR_USED:
+				BlockUsed[block] = 1;
+				continue;
+			case SECTOR_DELETED:
+				BlockDeleted[block] = 1;
+				continue;
+			default:
+				printk(KERN_WARNING "INFTL: unknown status "
+					"for block %d in EUN %d: 0x%x\n",
+					block, thisEUN, status);
+			}
+		}
+
+		if (!silly--) {
+			printk(KERN_WARNING "INFTL: infinite loop in Virtual "
+				"Unit Chain 0x%x\n", thisVUC);
+			return;
+		}
+
+		thisEUN = inftl->PUtable[thisEUN];
+	}
+
+	for (block = 0; block < inftl->EraseSize/SECTORSIZE; block++)
+		if (BlockUsed[block])
+			return;
+
+	/*
+	 * For each block in the chain free it and make it available
+	 * for future use. Erase from the oldest unit first.
+	 */
+	pr_debug("INFTL: deleting empty VUC %d\n", thisVUC);
+
+	for (;;) {
+		u16 *prevEUN = &inftl->VUtable[thisVUC];
+		thisEUN = *prevEUN;
+
+		/* If the chain is all gone already, we're done */
+		if (thisEUN == BLOCK_NIL) {
+			pr_debug("INFTL: Empty VUC %d for deletion was already absent\n", thisEUN);
+			return;
+		}
+
+		/* Find oldest unit in chain. */
+		while (inftl->PUtable[thisEUN] != BLOCK_NIL) {
+			BUG_ON(thisEUN >= inftl->nb_blocks);
+
+			prevEUN = &inftl->PUtable[thisEUN];
+			thisEUN = *prevEUN;
+		}
+
+		pr_debug("Deleting EUN %d from VUC %d\n",
+		      thisEUN, thisVUC);
+
+		if (INFTL_formatblock(inftl, thisEUN) < 0) {
+			/*
+			 * Could not erase : mark block as reserved.
+			 */
+			inftl->PUtable[thisEUN] = BLOCK_RESERVED;
+		} else {
+			/* Correctly erased : mark it as free */
+			inftl->PUtable[thisEUN] = BLOCK_FREE;
+			inftl->numfreeEUNs++;
+		}
+
+		/* Now sort out whatever was pointing to it... */
+		*prevEUN = BLOCK_NIL;
+
+		/* Ideally we'd actually be responsive to new
+		   requests while we're doing this -- if there's
+		   free space why should others be made to wait? */
+		cond_resched();
+	}
+
+	inftl->VUtable[thisVUC] = BLOCK_NIL;
+}
+
+static int INFTL_deleteblock(struct INFTLrecord *inftl, unsigned block)
+{
+	unsigned int thisEUN = inftl->VUtable[block / (inftl->EraseSize / SECTORSIZE)];
+	unsigned long blockofs = (block * SECTORSIZE) & (inftl->EraseSize - 1);
+	struct mtd_info *mtd = inftl->mbd.mtd;
+	unsigned int status;
+	int silly = MAX_LOOPS;
+	size_t retlen;
+	struct inftl_bci bci;
+
+	pr_debug("INFTL: INFTL_deleteblock(inftl=%p,"
+		"block=%d)\n", inftl, block);
+
+	while (thisEUN < inftl->nb_blocks) {
+		if (inftl_read_oob(mtd, (thisEUN * inftl->EraseSize) +
+				   blockofs, 8, &retlen, (char *)&bci) < 0)
+			status = SECTOR_IGNORE;
+		else
+			status = bci.Status | bci.Status1;
+
+		switch (status) {
+		case SECTOR_FREE:
+		case SECTOR_IGNORE:
+			break;
+		case SECTOR_DELETED:
+			thisEUN = BLOCK_NIL;
+			goto foundit;
+		case SECTOR_USED:
+			goto foundit;
+		default:
+			printk(KERN_WARNING "INFTL: unknown status for "
+				"block %d in EUN %d: 0x%x\n",
+				block, thisEUN, status);
+			break;
+		}
+
+		if (!silly--) {
+			printk(KERN_WARNING "INFTL: infinite loop in Virtual "
+				"Unit Chain 0x%x\n",
+				block / (inftl->EraseSize / SECTORSIZE));
+			return 1;
+		}
+		thisEUN = inftl->PUtable[thisEUN];
+	}
+
+foundit:
+	if (thisEUN != BLOCK_NIL) {
+		loff_t ptr = (thisEUN * inftl->EraseSize) + blockofs;
+
+		if (inftl_read_oob(mtd, ptr, 8, &retlen, (char *)&bci) < 0)
+			return -EIO;
+		bci.Status = bci.Status1 = SECTOR_DELETED;
+		if (inftl_write_oob(mtd, ptr, 8, &retlen, (char *)&bci) < 0)
+			return -EIO;
+		INFTL_trydeletechain(inftl, block / (inftl->EraseSize / SECTORSIZE));
+	}
+	return 0;
+}
+
+static int inftl_writeblock(struct mtd_blktrans_dev *mbd, unsigned long block,
+			    char *buffer)
+{
+	struct INFTLrecord *inftl = (void *)mbd;
+	unsigned int writeEUN;
+	unsigned long blockofs = (block * SECTORSIZE) & (inftl->EraseSize - 1);
+	size_t retlen;
+	struct inftl_oob oob;
+	char *p, *pend;
+
+	pr_debug("INFTL: inftl_writeblock(inftl=%p,block=%ld,"
+		"buffer=%p)\n", inftl, block, buffer);
+
+	/* Is block all zero? */
+	pend = buffer + SECTORSIZE;
+	for (p = buffer; p < pend && !*p; p++)
+		;
+
+	if (p < pend) {
+		writeEUN = INFTL_findwriteunit(inftl, block);
+
+		if (writeEUN == BLOCK_NIL) {
+			printk(KERN_WARNING "inftl_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 inftl_oob));
+		oob.b.Status = oob.b.Status1 = SECTOR_USED;
+
+		inftl_write(inftl->mbd.mtd, (writeEUN * inftl->EraseSize) +
+			    blockofs, SECTORSIZE, &retlen, (char *)buffer,
+			    (char *)&oob);
+		/*
+		 * need to write SECTOR_USED flags since they are not written
+		 * in mtd_writeecc
+		 */
+	} else {
+		INFTL_deleteblock(inftl, block);
+	}
+
+	return 0;
+}
+
+static int inftl_readblock(struct mtd_blktrans_dev *mbd, unsigned long block,
+			   char *buffer)
+{
+	struct INFTLrecord *inftl = (void *)mbd;
+	unsigned int thisEUN = inftl->VUtable[block / (inftl->EraseSize / SECTORSIZE)];
+	unsigned long blockofs = (block * SECTORSIZE) & (inftl->EraseSize - 1);
+	struct mtd_info *mtd = inftl->mbd.mtd;
+	unsigned int status;
+	int silly = MAX_LOOPS;
+	struct inftl_bci bci;
+	size_t retlen;
+
+	pr_debug("INFTL: inftl_readblock(inftl=%p,block=%ld,"
+		"buffer=%p)\n", inftl, block, buffer);
+
+	while (thisEUN < inftl->nb_blocks) {
+		if (inftl_read_oob(mtd, (thisEUN * inftl->EraseSize) +
+				  blockofs, 8, &retlen, (char *)&bci) < 0)
+			status = SECTOR_IGNORE;
+		else
+			status = bci.Status | bci.Status1;
+
+		switch (status) {
+		case SECTOR_DELETED:
+			thisEUN = BLOCK_NIL;
+			goto foundit;
+		case SECTOR_USED:
+			goto foundit;
+		case SECTOR_FREE:
+		case SECTOR_IGNORE:
+			break;
+		default:
+			printk(KERN_WARNING "INFTL: unknown status for "
+				"block %ld in EUN %d: 0x%04x\n",
+				block, thisEUN, status);
+			break;
+		}
+
+		if (!silly--) {
+			printk(KERN_WARNING "INFTL: infinite loop in "
+				"Virtual Unit Chain 0x%lx\n",
+				block / (inftl->EraseSize / SECTORSIZE));
+			return 1;
+		}
+
+		thisEUN = inftl->PUtable[thisEUN];
+	}
+
+foundit:
+	if (thisEUN == BLOCK_NIL) {
+		/* The requested block is not on the media, return all 0x00 */
+		memset(buffer, 0, SECTORSIZE);
+	} else {
+		size_t retlen;
+		loff_t ptr = (thisEUN * inftl->EraseSize) + blockofs;
+		int ret = mtd_read(mtd, ptr, SECTORSIZE, &retlen, buffer);
+
+		/* Handle corrected bit flips gracefully */
+		if (ret < 0 && !mtd_is_bitflip(ret))
+			return -EIO;
+	}
+	return 0;
+}
+
+static int inftl_getgeo(struct mtd_blktrans_dev *dev, struct hd_geometry *geo)
+{
+	struct INFTLrecord *inftl = (void *)dev;
+
+	geo->heads = inftl->heads;
+	geo->sectors = inftl->sectors;
+	geo->cylinders = inftl->cylinders;
+
+	return 0;
+}
+
+static struct mtd_blktrans_ops inftl_tr = {
+	.name		= "inftl",
+	.major		= INFTL_MAJOR,
+	.part_bits	= INFTL_PARTN_BITS,
+	.blksize 	= 512,
+	.getgeo		= inftl_getgeo,
+	.readsect	= inftl_readblock,
+	.writesect	= inftl_writeblock,
+	.add_mtd	= inftl_add_mtd,
+	.remove_dev	= inftl_remove_dev,
+	.owner		= THIS_MODULE,
+};
+
+module_mtd_blktrans(inftl_tr);
+
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Greg Ungerer <gerg@snapgear.com>, David Woodhouse <dwmw2@infradead.org>, Fabrice Bellard <fabrice.bellard@netgem.com> et al.");
+MODULE_DESCRIPTION("Support code for Inverse Flash Translation Layer, used on M-Systems DiskOnChip 2000, Millennium and Millennium Plus");