inftlcore.c

基于linux-2.6.28的mtd驱动

	DEBUG(MTD_DEBUG_LEVEL3, "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;
			DEBUG(MTD_DEBUG_LEVEL3, "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 0xffff;
			}

			/* 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, 0xffff);

			/*
			 * Hopefully we free something, lets try again.
			 * This time we are desperate...
			 */
			DEBUG(MTD_DEBUG_LEVEL1, "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 0xffff;
}

/*
 * 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;

	DEBUG(MTD_DEBUG_LEVEL3, "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.
	 */
	DEBUG(MTD_DEBUG_LEVEL1, "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) {
			DEBUG(MTD_DEBUG_LEVEL2, "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;
		}

		DEBUG(MTD_DEBUG_LEVEL3, "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;

	DEBUG(MTD_DEBUG_LEVEL3, "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;

	DEBUG(MTD_DEBUG_LEVEL3, "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;

	DEBUG(MTD_DEBUG_LEVEL3, "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 && ret != -EUCLEAN)
			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,
};

static int __init init_inftl(void)
{
	return register_mtd_blktrans(&inftl_tr);
}

static void __exit cleanup_inftl(void)
{
	deregister_mtd_blktrans(&inftl_tr);
}

module_init(init_inftl);
module_exit(cleanup_inftl);

MODULE_LICENSE("GPL");
MODULE_AUTHOR("Greg Ungerer <[e-mail]>, David Woodhouse <[e-mail]>, Fabrice Bellard <[e-mail]> et al.");
MODULE_DESCRIPTION("Support code for Inverse Flash Translation Layer, used on M-Systems DiskOnChip 2000, Millennium and Millennium Plus");