/*
   * rfd_ftl.c -- resident flash disk (flash translation layer)
   *

   * Copyright © 2005  Sean Young <sean@mess.org>

   *

   * This type of flash translation layer (FTL) is used by the Embedded BIOS
   * by General Software. It is known as the Resident Flash Disk (RFD), see:
   *
   *	http://www.gensw.com/pages/prod/bios/rfd.htm
   *
   * based on ftl.c
   */
  
  #include <linux/hdreg.h>
  #include <linux/init.h>
  #include <linux/mtd/blktrans.h>
  #include <linux/mtd/mtd.h>
  #include <linux/vmalloc.h>

  #include <linux/slab.h>

  #include <linux/jiffies.h>

  
  #include <asm/types.h>

  static int block_size = 0;
  module_param(block_size, int, 0);
  MODULE_PARM_DESC(block_size, "Block size to use by RFD, defaults to erase unit size");
  
  #define PREFIX "rfd_ftl: "

  /* This major has been assigned by device@lanana.org */

  #ifndef RFD_FTL_MAJOR

  #define RFD_FTL_MAJOR		256

  #endif
  
  /* Maximum number of partitions in an FTL region */
  #define PART_BITS		4
  
  /* An erase unit should start with this value */
  #define RFD_MAGIC		0x9193
  
  /* the second value is 0xffff or 0xffc8; function unknown */
  
  /* the third value is always 0xffff, ignored */
  
  /* next is an array of mapping for each corresponding sector */
  #define HEADER_MAP_OFFSET	3
  #define SECTOR_DELETED		0x0000
  #define SECTOR_ZERO		0xfffe
  #define SECTOR_FREE		0xffff
  
  #define SECTOR_SIZE		512
  
  #define SECTORS_PER_TRACK	63
  
  struct block {
  	enum {
  		BLOCK_OK,
  		BLOCK_ERASING,
  		BLOCK_ERASED,

  		BLOCK_UNUSED,

  		BLOCK_FAILED
  	} state;
  	int free_sectors;
  	int used_sectors;
  	int erases;
  	u_long offset;
  };
  
  struct partition {
  	struct mtd_blktrans_dev mbd;
  
  	u_int block_size;		/* size of erase unit */
  	u_int total_blocks;		/* number of erase units */
  	u_int header_sectors_per_block;	/* header sectors in erase unit */
  	u_int data_sectors_per_block;	/* data sectors in erase unit */
  	u_int sector_count;		/* sectors in translated disk */
  	u_int header_size;		/* bytes in header sector */
  	int reserved_block;		/* block next up for reclaim */
  	int current_block;		/* block to write to */
  	u16 *header_cache;		/* cached header */
  
  	int is_reclaiming;
  	int cylinders;
  	int errors;
  	u_long *sector_map;
  	struct block *blocks;
  };
  
  static int rfd_ftl_writesect(struct mtd_blktrans_dev *dev, u_long sector, char *buf);
  
  static int build_block_map(struct partition *part, int block_no)
  {
  	struct block *block = &part->blocks[block_no];
  	int i;

  	block->offset = part->block_size * block_no;
  
  	if (le16_to_cpu(part->header_cache[0]) != RFD_MAGIC) {

  		block->state = BLOCK_UNUSED;
  		return -ENOENT;

  	}
  
  	block->state = BLOCK_OK;
  
  	for (i=0; i<part->data_sectors_per_block; i++) {
  		u16 entry;

  		entry = le16_to_cpu(part->header_cache[HEADER_MAP_OFFSET + i]);
  
  		if (entry == SECTOR_DELETED)
  			continue;

  		if (entry == SECTOR_FREE) {
  			block->free_sectors++;
  			continue;
  		}
  
  		if (entry == SECTOR_ZERO)
  			entry = 0;

  		if (entry >= part->sector_count) {

  			printk(KERN_WARNING PREFIX

  				"'%s': unit #%d: entry %d corrupt, "
  				"sector %d out of range
  ",
  				part->mbd.mtd->name, block_no, i, entry);
  			continue;
  		}
  
  		if (part->sector_map[entry] != -1) {

  			printk(KERN_WARNING PREFIX

  				"'%s': more than one entry for sector %d
  ",
  				part->mbd.mtd->name, entry);
  			part->errors = 1;
  			continue;
  		}

  		part->sector_map[entry] = block->offset +

  			(i + part->header_sectors_per_block) * SECTOR_SIZE;
  
  		block->used_sectors++;
  	}
  
  	if (block->free_sectors == part->data_sectors_per_block)
  		part->reserved_block = block_no;
  
  	return 0;
  }
  
  static int scan_header(struct partition *part)
  {
  	int sectors_per_block;
  	int i, rc = -ENOMEM;
  	int blocks_found;
  	size_t retlen;
  
  	sectors_per_block = part->block_size / SECTOR_SIZE;

  	part->total_blocks = (u32)part->mbd.mtd->size / part->block_size;

  
  	if (part->total_blocks < 2)
  		return -ENOENT;
  
  	/* each erase block has three bytes header, followed by the map */

  	part->header_sectors_per_block =
  			((HEADER_MAP_OFFSET + sectors_per_block) *

  			sizeof(u16) + SECTOR_SIZE - 1) / SECTOR_SIZE;

  	part->data_sectors_per_block = sectors_per_block -

  			part->header_sectors_per_block;

  	part->header_size = (HEADER_MAP_OFFSET +

  			part->data_sectors_per_block) * sizeof(u16);
  
  	part->cylinders = (part->data_sectors_per_block *
  			(part->total_blocks - 1) - 1) / SECTORS_PER_TRACK;
  
  	part->sector_count = part->cylinders * SECTORS_PER_TRACK;
  
  	part->current_block = -1;
  	part->reserved_block = -1;
  	part->is_reclaiming = 0;
  
  	part->header_cache = kmalloc(part->header_size, GFP_KERNEL);
  	if (!part->header_cache)
  		goto err;

  	part->blocks = kcalloc(part->total_blocks, sizeof(struct block),

  			GFP_KERNEL);
  	if (!part->blocks)
  		goto err;
  
  	part->sector_map = vmalloc(part->sector_count * sizeof(u_long));
  	if (!part->sector_map) {
  		printk(KERN_ERR PREFIX "'%s': unable to allocate memory for "
  			"sector map", part->mbd.mtd->name);
  		goto err;
  	}

  	for (i=0; i<part->sector_count; i++)

  		part->sector_map[i] = -1;
  
  	for (i=0, blocks_found=0; i<part->total_blocks; i++) {

  		rc = part->mbd.mtd->read(part->mbd.mtd,

  				i * part->block_size, part->header_size,
  				&retlen, (u_char*)part->header_cache);
  
  		if (!rc && retlen != part->header_size)
  			rc = -EIO;

  		if (rc)

  			goto err;
  
  		if (!build_block_map(part, i))
  			blocks_found++;
  	}
  
  	if (blocks_found == 0) {
  		printk(KERN_NOTICE PREFIX "no RFD magic found in '%s'
  ",
  				part->mbd.mtd->name);
  		rc = -ENOENT;
  		goto err;
  	}
  
  	if (part->reserved_block == -1) {

  		printk(KERN_WARNING PREFIX "'%s': no empty erase unit found
  ",

  				part->mbd.mtd->name);
  
  		part->errors = 1;
  	}
  
  	return 0;
  
  err:
  	vfree(part->sector_map);
  	kfree(part->header_cache);
  	kfree(part->blocks);
  
  	return rc;
  }
  
  static int rfd_ftl_readsect(struct mtd_blktrans_dev *dev, u_long sector, char *buf)
  {
  	struct partition *part = (struct partition*)dev;
  	u_long addr;
  	size_t retlen;
  	int rc;

  	if (sector >= part->sector_count)
  		return -EIO;
  
  	addr = part->sector_map[sector];
  	if (addr != -1) {
  		rc = part->mbd.mtd->read(part->mbd.mtd, addr, SECTOR_SIZE,
  						&retlen, (u_char*)buf);
  		if (!rc && retlen != SECTOR_SIZE)
  			rc = -EIO;
  
  		if (rc) {
  			printk(KERN_WARNING PREFIX "error reading '%s' at "
  				"0x%lx
  ", part->mbd.mtd->name, addr);
  			return rc;
  		}
  	} else
  		memset(buf, 0, SECTOR_SIZE);

  	return 0;

  }

  
  static void erase_callback(struct erase_info *erase)
  {
  	struct partition *part;
  	u16 magic;
  	int i, rc;
  	size_t retlen;
  
  	part = (struct partition*)erase->priv;

  	i = (u32)erase->addr / part->block_size;
  	if (i >= part->total_blocks || part->blocks[i].offset != erase->addr ||
  	    erase->addr > UINT_MAX) {
  		printk(KERN_ERR PREFIX "erase callback for unknown offset %llx "
  				"on '%s'
  ", (unsigned long long)erase->addr, part->mbd.mtd->name);

  		return;
  	}
  
  	if (erase->state != MTD_ERASE_DONE) {

  		printk(KERN_WARNING PREFIX "erase failed at 0x%llx on '%s', "
  				"state %d
  ", (unsigned long long)erase->addr,

  				part->mbd.mtd->name, erase->state);
  
  		part->blocks[i].state = BLOCK_FAILED;
  		part->blocks[i].free_sectors = 0;
  		part->blocks[i].used_sectors = 0;
  
  		kfree(erase);
  
  		return;
  	}

  	magic = cpu_to_le16(RFD_MAGIC);

  
  	part->blocks[i].state = BLOCK_ERASED;
  	part->blocks[i].free_sectors = part->data_sectors_per_block;
  	part->blocks[i].used_sectors = 0;
  	part->blocks[i].erases++;

  	rc = part->mbd.mtd->write(part->mbd.mtd,
  		part->blocks[i].offset, sizeof(magic), &retlen,

  		(u_char*)&magic);

  	if (!rc && retlen != sizeof(magic))
  		rc = -EIO;
  
  	if (rc) {

  		printk(KERN_ERR PREFIX "'%s': unable to write RFD "

  				"header at 0x%lx
  ",

  				part->mbd.mtd->name,

  				part->blocks[i].offset);
  		part->blocks[i].state = BLOCK_FAILED;
  	}
  	else
  		part->blocks[i].state = BLOCK_OK;
  
  	kfree(erase);
  }
  
  static int erase_block(struct partition *part, int block)
  {
  	struct erase_info *erase;
  	int rc = -ENOMEM;
  
  	erase = kmalloc(sizeof(struct erase_info), GFP_KERNEL);
  	if (!erase)
  		goto err;
  
  	erase->mtd = part->mbd.mtd;
  	erase->callback = erase_callback;
  	erase->addr = part->blocks[block].offset;
  	erase->len = part->block_size;
  	erase->priv = (u_long)part;
  
  	part->blocks[block].state = BLOCK_ERASING;
  	part->blocks[block].free_sectors = 0;
  
  	rc = part->mbd.mtd->erase(part->mbd.mtd, erase);
  
  	if (rc) {

  		printk(KERN_ERR PREFIX "erase of region %llx,%llx on '%s' "
  				"failed
  ", (unsigned long long)erase->addr,
  				(unsigned long long)erase->len, part->mbd.mtd->name);

  		kfree(erase);
  	}
  
  err:
  	return rc;
  }
  
  static int move_block_contents(struct partition *part, int block_no, u_long *old_sector)
  {
  	void *sector_data;
  	u16 *map;
  	size_t retlen;
  	int i, rc = -ENOMEM;
  
  	part->is_reclaiming = 1;
  
  	sector_data = kmalloc(SECTOR_SIZE, GFP_KERNEL);
  	if (!sector_data)
  		goto err3;
  
  	map = kmalloc(part->header_size, GFP_KERNEL);
  	if (!map)
  		goto err2;

  
  	rc = part->mbd.mtd->read(part->mbd.mtd,
  		part->blocks[block_no].offset, part->header_size,

  		&retlen, (u_char*)map);

  	if (!rc && retlen != part->header_size)
  		rc = -EIO;
  
  	if (rc) {

  		printk(KERN_ERR PREFIX "error reading '%s' at "

  			"0x%lx
  ", part->mbd.mtd->name,

  			part->blocks[block_no].offset);
  
  		goto err;
  	}
  
  	for (i=0; i<part->data_sectors_per_block; i++) {
  		u16 entry = le16_to_cpu(map[HEADER_MAP_OFFSET + i]);
  		u_long addr;
  
  
  		if (entry == SECTOR_FREE || entry == SECTOR_DELETED)
  			continue;

  		if (entry == SECTOR_ZERO)

  			entry = 0;
  
  		/* already warned about and ignored in build_block_map() */

  		if (entry >= part->sector_count)

  			continue;
  
  		addr = part->blocks[block_no].offset +
  			(i + part->header_sectors_per_block) * SECTOR_SIZE;
  
  		if (*old_sector == addr) {
  			*old_sector = -1;
  			if (!part->blocks[block_no].used_sectors--) {
  				rc = erase_block(part, block_no);
  				break;
  			}
  			continue;
  		}
  		rc = part->mbd.mtd->read(part->mbd.mtd, addr,
  			SECTOR_SIZE, &retlen, sector_data);

  		if (!rc && retlen != SECTOR_SIZE)
  			rc = -EIO;
  
  		if (rc) {

  			printk(KERN_ERR PREFIX "'%s': Unable to "

  				"read sector for relocation
  ",
  				part->mbd.mtd->name);
  
  			goto err;
  		}

  		rc = rfd_ftl_writesect((struct mtd_blktrans_dev*)part,
  				entry, sector_data);

  
  		if (rc)

  			goto err;
  	}
  
  err:
  	kfree(map);
  err2:
  	kfree(sector_data);
  err3:
  	part->is_reclaiming = 0;
  
  	return rc;
  }

  static int reclaim_block(struct partition *part, u_long *old_sector)

  {
  	int block, best_block, score, old_sector_block;
  	int rc;

  	/* we have a race if sync doesn't exist */
  	if (part->mbd.mtd->sync)
  		part->mbd.mtd->sync(part->mbd.mtd);
  
  	score = 0x7fffffff; /* MAX_INT */
  	best_block = -1;
  	if (*old_sector != -1)
  		old_sector_block = *old_sector / part->block_size;
  	else
  		old_sector_block = -1;
  
  	for (block=0; block<part->total_blocks; block++) {
  		int this_score;
  
  		if (block == part->reserved_block)
  			continue;
  
  		/*
  		 * Postpone reclaiming if there is a free sector as
  		 * more removed sectors is more efficient (have to move
  		 * less).
  		 */

  		if (part->blocks[block].free_sectors)

  			return 0;
  
  		this_score = part->blocks[block].used_sectors;

  		if (block == old_sector_block)

  			this_score--;
  		else {
  			/* no point in moving a full block */

  			if (part->blocks[block].used_sectors ==

  					part->data_sectors_per_block)
  				continue;
  		}
  
  		this_score += part->blocks[block].erases;
  
  		if (this_score < score) {
  			best_block = block;
  			score = this_score;
  		}
  	}
  
  	if (best_block == -1)
  		return -ENOSPC;
  
  	part->current_block = -1;
  	part->reserved_block = best_block;
  
  	pr_debug("reclaim_block: reclaiming block #%d with %d used "
  		 "%d free sectors
  ", best_block,
  		 part->blocks[best_block].used_sectors,
  		 part->blocks[best_block].free_sectors);
  
  	if (part->blocks[best_block].used_sectors)
  		rc = move_block_contents(part, best_block, old_sector);
  	else
  		rc = erase_block(part, best_block);
  
  	return rc;
  }
  
  /*
   * IMPROVE: It would be best to choose the block with the most deleted sectors,
   * because if we fill that one up first it'll have the most chance of having
   * the least live sectors at reclaim.
   */

  static int find_free_block(struct partition *part)

  {
  	int block, stop;
  
  	block = part->current_block == -1 ?
  			jiffies % part->total_blocks : part->current_block;
  	stop = block;
  
  	do {

  		if (part->blocks[block].free_sectors &&

  				block != part->reserved_block)
  			return block;

  		if (part->blocks[block].state == BLOCK_UNUSED)
  			erase_block(part, block);

  		if (++block >= part->total_blocks)
  			block = 0;
  
  	} while (block != stop);
  
  	return -1;
  }

  static int find_writable_block(struct partition *part, u_long *old_sector)

  {
  	int rc, block;
  	size_t retlen;
  
  	block = find_free_block(part);
  
  	if (block == -1) {
  		if (!part->is_reclaiming) {
  			rc = reclaim_block(part, old_sector);
  			if (rc)
  				goto err;
  
  			block = find_free_block(part);
  		}
  
  		if (block == -1) {
  			rc = -ENOSPC;
  			goto err;
  		}
  	}

  	rc = part->mbd.mtd->read(part->mbd.mtd, part->blocks[block].offset,

  		part->header_size, &retlen, (u_char*)part->header_cache);
  
  	if (!rc && retlen != part->header_size)
  		rc = -EIO;
  
  	if (rc) {

  		printk(KERN_ERR PREFIX "'%s': unable to read header at "

  				"0x%lx
  ", part->mbd.mtd->name,

  				part->blocks[block].offset);
  		goto err;
  	}
  
  	part->current_block = block;
  
  err:
  	return rc;

  }

  
  static int mark_sector_deleted(struct partition *part, u_long old_addr)
  {
  	int block, offset, rc;
  	u_long addr;
  	size_t retlen;

  	u16 del = cpu_to_le16(SECTOR_DELETED);

  
  	block = old_addr / part->block_size;

  	offset = (old_addr % part->block_size) / SECTOR_SIZE -

  		part->header_sectors_per_block;
  
  	addr = part->blocks[block].offset +
  			(HEADER_MAP_OFFSET + offset) * sizeof(u16);
  	rc = part->mbd.mtd->write(part->mbd.mtd, addr,
  		sizeof(del), &retlen, (u_char*)&del);
  
  	if (!rc && retlen != sizeof(del))
  		rc = -EIO;
  
  	if (rc) {

  		printk(KERN_ERR PREFIX "error writing '%s' at "

  			"0x%lx
  ", part->mbd.mtd->name, addr);

  		if (rc)

  			goto err;
  	}
  	if (block == part->current_block)
  		part->header_cache[offset + HEADER_MAP_OFFSET] = del;
  
  	part->blocks[block].used_sectors--;
  
  	if (!part->blocks[block].used_sectors &&
  	    !part->blocks[block].free_sectors)
  		rc = erase_block(part, block);
  
  err:
  	return rc;
  }
  
  static int find_free_sector(const struct partition *part, const struct block *block)
  {
  	int i, stop;
  
  	i = stop = part->data_sectors_per_block - block->free_sectors;
  
  	do {

  		if (le16_to_cpu(part->header_cache[HEADER_MAP_OFFSET + i])

  				== SECTOR_FREE)
  			return i;
  
  		if (++i == part->data_sectors_per_block)
  			i = 0;
  	}
  	while(i != stop);
  
  	return -1;
  }
  
  static int do_writesect(struct mtd_blktrans_dev *dev, u_long sector, char *buf, ulong *old_addr)
  {
  	struct partition *part = (struct partition*)dev;
  	struct block *block;
  	u_long addr;
  	int i;
  	int rc;
  	size_t retlen;
  	u16 entry;
  
  	if (part->current_block == -1 ||
  		!part->blocks[part->current_block].free_sectors) {

  		rc = find_writable_block(part, old_addr);

  		if (rc)

  			goto err;
  	}
  
  	block = &part->blocks[part->current_block];
  
  	i = find_free_sector(part, block);
  
  	if (i < 0) {
  		rc = -ENOSPC;
  		goto err;
  	}

  
  	addr = (i + part->header_sectors_per_block) * SECTOR_SIZE +

  		block->offset;

  	rc = part->mbd.mtd->write(part->mbd.mtd,

  		addr, SECTOR_SIZE, &retlen, (u_char*)buf);
  
  	if (!rc && retlen != SECTOR_SIZE)
  		rc = -EIO;
  
  	if (rc) {

  		printk(KERN_ERR PREFIX "error writing '%s' at 0x%lx
  ",

  				part->mbd.mtd->name, addr);

  		if (rc)

  			goto err;
  	}
  
  	part->sector_map[sector] = addr;
  
  	entry = cpu_to_le16(sector == 0 ? SECTOR_ZERO : sector);
  
  	part->header_cache[i + HEADER_MAP_OFFSET] = entry;
  
  	addr = block->offset + (HEADER_MAP_OFFSET + i) * sizeof(u16);
  	rc = part->mbd.mtd->write(part->mbd.mtd, addr,
  			sizeof(entry), &retlen, (u_char*)&entry);
  
  	if (!rc && retlen != sizeof(entry))
  		rc = -EIO;
  
  	if (rc) {

  		printk(KERN_ERR PREFIX "error writing '%s' at 0x%lx
  ",

  				part->mbd.mtd->name, addr);

  		if (rc)

  			goto err;
  	}
  	block->used_sectors++;
  	block->free_sectors--;
  
  err:
  	return rc;
  }
  
  static int rfd_ftl_writesect(struct mtd_blktrans_dev *dev, u_long sector, char *buf)
  {
  	struct partition *part = (struct partition*)dev;
  	u_long old_addr;
  	int i;
  	int rc = 0;
  
  	pr_debug("rfd_ftl_writesect(sector=0x%lx)
  ", sector);
  
  	if (part->reserved_block == -1) {
  		rc = -EACCES;
  		goto err;
  	}
  
  	if (sector >= part->sector_count) {
  		rc = -EIO;
  		goto err;
  	}
  
  	old_addr = part->sector_map[sector];
  
  	for (i=0; i<SECTOR_SIZE; i++) {
  		if (!buf[i])
  			continue;
  
  		rc = do_writesect(dev, sector, buf, &old_addr);
  		if (rc)
  			goto err;
  		break;
  	}

  	if (i == SECTOR_SIZE)

  		part->sector_map[sector] = -1;
  
  	if (old_addr != -1)
  		rc = mark_sector_deleted(part, old_addr);
  
  err:
  	return rc;
  }
  
  static int rfd_ftl_getgeo(struct mtd_blktrans_dev *dev, struct hd_geometry *geo)
  {
  	struct partition *part = (struct partition*)dev;
  
  	geo->heads = 1;
  	geo->sectors = SECTORS_PER_TRACK;
  	geo->cylinders = part->cylinders;
  
  	return 0;
  }
  
  static void rfd_ftl_add_mtd(struct mtd_blktrans_ops *tr, struct mtd_info *mtd)
  {
  	struct partition *part;

  	if (mtd->type != MTD_NORFLASH || mtd->size > UINT_MAX)

  		return;

  	part = kzalloc(sizeof(struct partition), GFP_KERNEL);

  	if (!part)
  		return;
  
  	part->mbd.mtd = mtd;
  
  	if (block_size)
  		part->block_size = block_size;
  	else {
  		if (!mtd->erasesize) {

  			printk(KERN_WARNING PREFIX "please provide block_size");

  			goto out;
  		} else

  			part->block_size = mtd->erasesize;
  	}
  
  	if (scan_header(part) == 0) {
  		part->mbd.size = part->sector_count;

  		part->mbd.tr = tr;
  		part->mbd.devnum = -1;
  		if (!(mtd->flags & MTD_WRITEABLE))
  			part->mbd.readonly = 1;
  		else if (part->errors) {

  			printk(KERN_WARNING PREFIX "'%s': errors found, "
  					"setting read-only
  ", mtd->name);

  			part->mbd.readonly = 1;
  		}
  
  		printk(KERN_INFO PREFIX "name: '%s' type: %d flags %x
  ",
  				mtd->name, mtd->type, mtd->flags);
  
  		if (!add_mtd_blktrans_dev((void*)part))
  			return;

  	}

  out:

  	kfree(part);
  }
  
  static void rfd_ftl_remove_dev(struct mtd_blktrans_dev *dev)
  {
  	struct partition *part = (struct partition*)dev;
  	int i;
  
  	for (i=0; i<part->total_blocks; i++) {
  		pr_debug("rfd_ftl_remove_dev:'%s': erase unit #%02d: %d erases
  ",
  			part->mbd.mtd->name, i, part->blocks[i].erases);
  	}
  
  	del_mtd_blktrans_dev(dev);
  	vfree(part->sector_map);
  	kfree(part->header_cache);
  	kfree(part->blocks);

  }

  static struct mtd_blktrans_ops rfd_ftl_tr = {

  	.name		= "rfd",
  	.major		= RFD_FTL_MAJOR,
  	.part_bits	= PART_BITS,

  	.blksize 	= SECTOR_SIZE,

  	.readsect	= rfd_ftl_readsect,

  	.writesect	= rfd_ftl_writesect,

  	.getgeo		= rfd_ftl_getgeo,
  	.add_mtd	= rfd_ftl_add_mtd,
  	.remove_dev	= rfd_ftl_remove_dev,
  	.owner		= THIS_MODULE,
  };
  
  static int __init init_rfd_ftl(void)
  {
  	return register_mtd_blktrans(&rfd_ftl_tr);
  }
  
  static void __exit cleanup_rfd_ftl(void)
  {
  	deregister_mtd_blktrans(&rfd_ftl_tr);
  }
  
  module_init(init_rfd_ftl);
  module_exit(cleanup_rfd_ftl);
  
  MODULE_LICENSE("GPL");
  MODULE_AUTHOR("Sean Young <sean@mess.org>");
  MODULE_DESCRIPTION("Support code for RFD Flash Translation Layer, "
  		"used by General Software's Embedded BIOS");