text: /*
   * Copyright (c) International Business Machines Corp., 2006
   * Copyright (c) Nokia Corporation, 2007
   *
   * This program is free software; you can redistribute it and/or modify
   * it under the terms of the GNU General Public License as published by
   * the Free Software Foundation; either version 2 of the License, or
   * (at your option) any later version.
   *
   * This program is distributed in the hope that it will be useful,
   * but WITHOUT ANY WARRANTY; without even the implied warranty of
   * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See
   * the GNU General Public License for more details.
   *
   * You should have received a copy of the GNU General Public License
   * along with this program; if not, write to the Free Software
   * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
   *
   * Author: Artem Bityutskiy (Битюцкий Артём),
   *         Frank Haverkamp
   */
  
  /*
   * This file includes UBI initialization and building of UBI devices.
   *
   * When UBI is initialized, it attaches all the MTD devices specified as the
   * module load parameters or the kernel boot parameters. If MTD devices were
   * specified, UBI does not attach any MTD device, but it is possible to do
   * later using the "UBI control device".
   *
   * At the moment we only attach UBI devices by scanning, which will become a
   * bottleneck when flashes reach certain large size. Then one may improve UBI
   * and add other methods, although it does not seem to be easy to do.
   */
  
  #ifdef UBI_LINUX
  #include <linux/err.h>
  #include <linux/module.h>
  #include <linux/moduleparam.h>
  #include <linux/stringify.h>
  #include <linux/stat.h>
  #include <linux/miscdevice.h>
  #include <linux/log2.h>
  #include <linux/kthread.h>
  #endif
  #include <ubi_uboot.h>
  #include "ubi.h"
  
  #if (CONFIG_SYS_MALLOC_LEN < (512 << 10))
  #error Malloc area too small for UBI, increase CONFIG_SYS_MALLOC_LEN to >= 512k
  #endif
  
  /* Maximum length of the 'mtd=' parameter */
  #define MTD_PARAM_LEN_MAX 64
  
  /**
   * struct mtd_dev_param - MTD device parameter description data structure.
   * @name: MTD device name or number string
   * @vid_hdr_offs: VID header offset
   */
  struct mtd_dev_param
  {
  	char name[MTD_PARAM_LEN_MAX];
  	int vid_hdr_offs;
  };
  
  /* Numbers of elements set in the @mtd_dev_param array */
  static int mtd_devs = 0;
  
  /* MTD devices specification parameters */
  static struct mtd_dev_param mtd_dev_param[UBI_MAX_DEVICES];
  
  /* Root UBI "class" object (corresponds to '/<sysfs>/class/ubi/') */
  struct class *ubi_class;
  
  #ifdef UBI_LINUX
  /* Slab cache for wear-leveling entries */
  struct kmem_cache *ubi_wl_entry_slab;
  
  /* UBI control character device */
  static struct miscdevice ubi_ctrl_cdev = {
  	.minor = MISC_DYNAMIC_MINOR,
  	.name = "ubi_ctrl",
  	.fops = &ubi_ctrl_cdev_operations,
  };
  #endif
  
  /* All UBI devices in system */
  struct ubi_device *ubi_devices[UBI_MAX_DEVICES];
  
  #ifdef UBI_LINUX
  /* Serializes UBI devices creations and removals */
  DEFINE_MUTEX(ubi_devices_mutex);
  
  /* Protects @ubi_devices and @ubi->ref_count */
  static DEFINE_SPINLOCK(ubi_devices_lock);
  
  /* "Show" method for files in '/<sysfs>/class/ubi/' */
  static ssize_t ubi_version_show(struct class *class, char *buf)
  {
  	return sprintf(buf, "%d\n", UBI_VERSION);
  }
  
  /* UBI version attribute ('/<sysfs>/class/ubi/version') */
  static struct class_attribute ubi_version =
  	__ATTR(version, S_IRUGO, ubi_version_show, NULL);
  
  static ssize_t dev_attribute_show(struct device *dev,
  				  struct device_attribute *attr, char *buf);
  
  /* UBI device attributes (correspond to files in '/<sysfs>/class/ubi/ubiX') */
  static struct device_attribute dev_eraseblock_size =
  	__ATTR(eraseblock_size, S_IRUGO, dev_attribute_show, NULL);
  static struct device_attribute dev_avail_eraseblocks =
  	__ATTR(avail_eraseblocks, S_IRUGO, dev_attribute_show, NULL);
  static struct device_attribute dev_total_eraseblocks =
  	__ATTR(total_eraseblocks, S_IRUGO, dev_attribute_show, NULL);
  static struct device_attribute dev_volumes_count =
  	__ATTR(volumes_count, S_IRUGO, dev_attribute_show, NULL);
  static struct device_attribute dev_max_ec =
  	__ATTR(max_ec, S_IRUGO, dev_attribute_show, NULL);
  static struct device_attribute dev_reserved_for_bad =
  	__ATTR(reserved_for_bad, S_IRUGO, dev_attribute_show, NULL);
  static struct device_attribute dev_bad_peb_count =
  	__ATTR(bad_peb_count, S_IRUGO, dev_attribute_show, NULL);
  static struct device_attribute dev_max_vol_count =
  	__ATTR(max_vol_count, S_IRUGO, dev_attribute_show, NULL);
  static struct device_attribute dev_min_io_size =
  	__ATTR(min_io_size, S_IRUGO, dev_attribute_show, NULL);
  static struct device_attribute dev_bgt_enabled =
  	__ATTR(bgt_enabled, S_IRUGO, dev_attribute_show, NULL);
  static struct device_attribute dev_mtd_num =
  	__ATTR(mtd_num, S_IRUGO, dev_attribute_show, NULL);
  #endif
  
  /**
   * ubi_get_device - get UBI device.
   * @ubi_num: UBI device number
   *
   * This function returns UBI device description object for UBI device number
   * @ubi_num, or %NULL if the device does not exist. This function increases the
   * device reference count to prevent removal of the device. In other words, the
   * device cannot be removed if its reference count is not zero.
   */
  struct ubi_device *ubi_get_device(int ubi_num)
  {
  	struct ubi_device *ubi;
  
  	spin_lock(&ubi_devices_lock);
  	ubi = ubi_devices[ubi_num];
  	if (ubi) {
  		ubi_assert(ubi->ref_count >= 0);
  		ubi->ref_count += 1;
  		get_device(&ubi->dev);
  	}
  	spin_unlock(&ubi_devices_lock);
  
  	return ubi;
  }
  
  /**
   * ubi_put_device - drop an UBI device reference.
   * @ubi: UBI device description object
   */
  void ubi_put_device(struct ubi_device *ubi)
  {
  	spin_lock(&ubi_devices_lock);
  	ubi->ref_count -= 1;
  	put_device(&ubi->dev);
  	spin_unlock(&ubi_devices_lock);
  }
  
  /**
   * ubi_get_by_major - get UBI device description object by character device
   *                    major number.
   * @major: major number
   *
   * This function is similar to 'ubi_get_device()', but it searches the device
   * by its major number.
   */
  struct ubi_device *ubi_get_by_major(int major)
  {
  	int i;
  	struct ubi_device *ubi;
  
  	spin_lock(&ubi_devices_lock);
  	for (i = 0; i < UBI_MAX_DEVICES; i++) {
  		ubi = ubi_devices[i];
  		if (ubi && MAJOR(ubi->cdev.dev) == major) {
  			ubi_assert(ubi->ref_count >= 0);
  			ubi->ref_count += 1;
  			get_device(&ubi->dev);
  			spin_unlock(&ubi_devices_lock);
  			return ubi;
  		}
  	}
  	spin_unlock(&ubi_devices_lock);
  
  	return NULL;
  }
  
  /**
   * ubi_major2num - get UBI device number by character device major number.
   * @major: major number
   *
   * This function searches UBI device number object by its major number. If UBI
   * device was not found, this function returns -ENODEV, otherwise the UBI device
   * number is returned.
   */
  int ubi_major2num(int major)
  {
  	int i, ubi_num = -ENODEV;
  
  	spin_lock(&ubi_devices_lock);
  	for (i = 0; i < UBI_MAX_DEVICES; i++) {
  		struct ubi_device *ubi = ubi_devices[i];
  
  		if (ubi && MAJOR(ubi->cdev.dev) == major) {
  			ubi_num = ubi->ubi_num;
  			break;
  		}
  	}
  	spin_unlock(&ubi_devices_lock);
  
  	return ubi_num;
  }
  
  #ifdef UBI_LINUX
  /* "Show" method for files in '/<sysfs>/class/ubi/ubiX/' */
  static ssize_t dev_attribute_show(struct device *dev,
  				  struct device_attribute *attr, char *buf)
  {
  	ssize_t ret;
  	struct ubi_device *ubi;
  
  	/*
  	 * The below code looks weird, but it actually makes sense. We get the
  	 * UBI device reference from the contained 'struct ubi_device'. But it
  	 * is unclear if the device was removed or not yet. Indeed, if the
  	 * device was removed before we increased its reference count,
  	 * 'ubi_get_device()' will return -ENODEV and we fail.
  	 *
  	 * Remember, 'struct ubi_device' is freed in the release function, so
  	 * we still can use 'ubi->ubi_num'.
  	 */
  	ubi = container_of(dev, struct ubi_device, dev);
  	ubi = ubi_get_device(ubi->ubi_num);
  	if (!ubi)
  		return -ENODEV;
  
  	if (attr == &dev_eraseblock_size)
  		ret = sprintf(buf, "%d\n", ubi->leb_size);
  	else if (attr == &dev_avail_eraseblocks)
  		ret = sprintf(buf, "%d\n", ubi->avail_pebs);
  	else if (attr == &dev_total_eraseblocks)
  		ret = sprintf(buf, "%d\n", ubi->good_peb_count);
  	else if (attr == &dev_volumes_count)
  		ret = sprintf(buf, "%d\n", ubi->vol_count - UBI_INT_VOL_COUNT);
  	else if (attr == &dev_max_ec)
  		ret = sprintf(buf, "%d\n", ubi->max_ec);
  	else if (attr == &dev_reserved_for_bad)
  		ret = sprintf(buf, "%d\n", ubi->beb_rsvd_pebs);
  	else if (attr == &dev_bad_peb_count)
  		ret = sprintf(buf, "%d\n", ubi->bad_peb_count);
  	else if (attr == &dev_max_vol_count)
  		ret = sprintf(buf, "%d\n", ubi->vtbl_slots);
  	else if (attr == &dev_min_io_size)
  		ret = sprintf(buf, "%d\n", ubi->min_io_size);
  	else if (attr == &dev_bgt_enabled)
  		ret = sprintf(buf, "%d\n", ubi->thread_enabled);
  	else if (attr == &dev_mtd_num)
  		ret = sprintf(buf, "%d\n", ubi->mtd->index);
  	else
  		ret = -EINVAL;
  
  	ubi_put_device(ubi);
  	return ret;
  }
  
  /* Fake "release" method for UBI devices */
  static void dev_release(struct device *dev) { }
  
  /**
   * ubi_sysfs_init - initialize sysfs for an UBI device.
   * @ubi: UBI device description object
   *
   * This function returns zero in case of success and a negative error code in
   * case of failure.
   */
  static int ubi_sysfs_init(struct ubi_device *ubi)
  {
  	int err;
  
  	ubi->dev.release = dev_release;
  	ubi->dev.devt = ubi->cdev.dev;
  	ubi->dev.class = ubi_class;
  	sprintf(&ubi->dev.bus_id[0], UBI_NAME_STR"%d", ubi->ubi_num);
  	err = device_register(&ubi->dev);
  	if (err)
  		return err;
  
  	err = device_create_file(&ubi->dev, &dev_eraseblock_size);
  	if (err)
  		return err;
  	err = device_create_file(&ubi->dev, &dev_avail_eraseblocks);
  	if (err)
  		return err;
  	err = device_create_file(&ubi->dev, &dev_total_eraseblocks);
  	if (err)
  		return err;
  	err = device_create_file(&ubi->dev, &dev_volumes_count);
  	if (err)
  		return err;
  	err = device_create_file(&ubi->dev, &dev_max_ec);
  	if (err)
  		return err;
  	err = device_create_file(&ubi->dev, &dev_reserved_for_bad);
  	if (err)
  		return err;
  	err = device_create_file(&ubi->dev, &dev_bad_peb_count);
  	if (err)
  		return err;
  	err = device_create_file(&ubi->dev, &dev_max_vol_count);
  	if (err)
  		return err;
  	err = device_create_file(&ubi->dev, &dev_min_io_size);
  	if (err)
  		return err;
  	err = device_create_file(&ubi->dev, &dev_bgt_enabled);
  	if (err)
  		return err;
  	err = device_create_file(&ubi->dev, &dev_mtd_num);
  	return err;
  }
  
  /**
   * ubi_sysfs_close - close sysfs for an UBI device.
   * @ubi: UBI device description object
   */
  static void ubi_sysfs_close(struct ubi_device *ubi)
  {
  	device_remove_file(&ubi->dev, &dev_mtd_num);
  	device_remove_file(&ubi->dev, &dev_bgt_enabled);
  	device_remove_file(&ubi->dev, &dev_min_io_size);
  	device_remove_file(&ubi->dev, &dev_max_vol_count);
  	device_remove_file(&ubi->dev, &dev_bad_peb_count);
  	device_remove_file(&ubi->dev, &dev_reserved_for_bad);
  	device_remove_file(&ubi->dev, &dev_max_ec);
  	device_remove_file(&ubi->dev, &dev_volumes_count);
  	device_remove_file(&ubi->dev, &dev_total_eraseblocks);
  	device_remove_file(&ubi->dev, &dev_avail_eraseblocks);
  	device_remove_file(&ubi->dev, &dev_eraseblock_size);
  	device_unregister(&ubi->dev);
  }
  #endif
  
  /**
   * kill_volumes - destroy all volumes.
   * @ubi: UBI device description object
   */
  static void kill_volumes(struct ubi_device *ubi)
  {
  	int i;
  
  	for (i = 0; i < ubi->vtbl_slots; i++)
  		if (ubi->volumes[i])
  			ubi_free_volume(ubi, ubi->volumes[i]);
  }
  
  /**
   * uif_init - initialize user interfaces for an UBI device.
   * @ubi: UBI device description object
   *
   * This function returns zero in case of success and a negative error code in
   * case of failure.
   */
  static int uif_init(struct ubi_device *ubi)
  {
  	int i, err;
  #ifdef UBI_LINUX
  	dev_t dev;
  #endif
  
  	sprintf(ubi->ubi_name, UBI_NAME_STR "%d", ubi->ubi_num);
  
  	/*
  	 * Major numbers for the UBI character devices are allocated
  	 * dynamically. Major numbers of volume character devices are
  	 * equivalent to ones of the corresponding UBI character device. Minor
  	 * numbers of UBI character devices are 0, while minor numbers of
  	 * volume character devices start from 1. Thus, we allocate one major
  	 * number and ubi->vtbl_slots + 1 minor numbers.
  	 */
  	err = alloc_chrdev_region(&dev, 0, ubi->vtbl_slots + 1, ubi->ubi_name);
  	if (err) {
  		ubi_err("cannot register UBI character devices");
  		return err;
  	}
  
  	ubi_assert(MINOR(dev) == 0);
  	cdev_init(&ubi->cdev, &ubi_cdev_operations);
  	dbg_msg("%s major is %u", ubi->ubi_name, MAJOR(dev));
  	ubi->cdev.owner = THIS_MODULE;
  
  	err = cdev_add(&ubi->cdev, dev, 1);
  	if (err) {
  		ubi_err("cannot add character device");
  		goto out_unreg;
  	}
  
  	err = ubi_sysfs_init(ubi);
  	if (err)
  		goto out_sysfs;
  
  	for (i = 0; i < ubi->vtbl_slots; i++)
  		if (ubi->volumes[i]) {
  			err = ubi_add_volume(ubi, ubi->volumes[i]);
  			if (err) {
  				ubi_err("cannot add volume %d", i);
  				goto out_volumes;
  			}
  		}
  
  	return 0;
  
  out_volumes:
  	kill_volumes(ubi);
  out_sysfs:
  	ubi_sysfs_close(ubi);
  	cdev_del(&ubi->cdev);
  out_unreg:
  	unregister_chrdev_region(ubi->cdev.dev, ubi->vtbl_slots + 1);
  	ubi_err("cannot initialize UBI %s, error %d", ubi->ubi_name, err);
  	return err;
  }
  
  /**
   * uif_close - close user interfaces for an UBI device.
   * @ubi: UBI device description object
   */
  static void uif_close(struct ubi_device *ubi)
  {
  	kill_volumes(ubi);
  	ubi_sysfs_close(ubi);
  	cdev_del(&ubi->cdev);
  	unregister_chrdev_region(ubi->cdev.dev, ubi->vtbl_slots + 1);
  }
  
  /**
   * attach_by_scanning - attach an MTD device using scanning method.
   * @ubi: UBI device descriptor
   *
   * This function returns zero in case of success and a negative error code in
   * case of failure.
   *
   * Note, currently this is the only method to attach UBI devices. Hopefully in
   * the future we'll have more scalable attaching methods and avoid full media
   * scanning. But even in this case scanning will be needed as a fall-back
   * attaching method if there are some on-flash table corruptions.
   */
  static int attach_by_scanning(struct ubi_device *ubi)
  {
  	int err;
  	struct ubi_scan_info *si;
  
  	si = ubi_scan(ubi);
  	if (IS_ERR(si))
  		return PTR_ERR(si);
  
  	ubi->bad_peb_count = si->bad_peb_count;
  	ubi->good_peb_count = ubi->peb_count - ubi->bad_peb_count;
  	ubi->max_ec = si->max_ec;
  	ubi->mean_ec = si->mean_ec;
  
  	err = ubi_read_volume_table(ubi, si);
  	if (err)
  		goto out_si;
  
  	err = ubi_wl_init_scan(ubi, si);
  	if (err)
  		goto out_vtbl;
  
  	err = ubi_eba_init_scan(ubi, si);
  	if (err)
  		goto out_wl;
  
  	ubi_scan_destroy_si(si);
  	return 0;
  
  out_wl:
  	ubi_wl_close(ubi);
  out_vtbl:
  	vfree(ubi->vtbl);
  out_si:
  	ubi_scan_destroy_si(si);
  	return err;
  }
  
  /**
   * io_init - initialize I/O unit for a given UBI device.
   * @ubi: UBI device description object
   *
   * If @ubi->vid_hdr_offset or @ubi->leb_start is zero, default offsets are
   * assumed:
   *   o EC header is always at offset zero - this cannot be changed;
   *   o VID header starts just after the EC header at the closest address
   *     aligned to @io->hdrs_min_io_size;
   *   o data starts just after the VID header at the closest address aligned to
   *     @io->min_io_size
   *
   * This function returns zero in case of success and a negative error code in
   * case of failure.
   */
  static int io_init(struct ubi_device *ubi)
  {
  	if (ubi->mtd->numeraseregions != 0) {
  		/*
  		 * Some flashes have several erase regions. Different regions
  		 * may have different eraseblock size and other
  		 * characteristics. It looks like mostly multi-region flashes
  		 * have one "main" region and one or more small regions to
  		 * store boot loader code or boot parameters or whatever. I
  		 * guess we should just pick the largest region. But this is
  		 * not implemented.
  		 */
  		ubi_err("multiple regions, not implemented");
  		return -EINVAL;
  	}
  
  	if (ubi->vid_hdr_offset < 0)
  		return -EINVAL;
  
  	/*
  	 * Note, in this implementation we support MTD devices with 0x7FFFFFFF
  	 * physical eraseblocks maximum.
  	 */
  
  	ubi->peb_size   = ubi->mtd->erasesize;
  	ubi->peb_count  = mtd_div_by_eb(ubi->mtd->size, ubi->mtd);
  	ubi->flash_size = ubi->mtd->size;
  
  	if (ubi->mtd->block_isbad && ubi->mtd->block_markbad)
  		ubi->bad_allowed = 1;
  
  	ubi->min_io_size = ubi->mtd->writesize;
  	ubi->hdrs_min_io_size = ubi->mtd->writesize >> ubi->mtd->subpage_sft;
  
  	/*
  	 * Make sure minimal I/O unit is power of 2. Note, there is no
  	 * fundamental reason for this assumption. It is just an optimization
  	 * which allows us to avoid costly division operations.
  	 */
  	if (!is_power_of_2(ubi->min_io_size)) {
  		ubi_err("min. I/O unit (%d) is not power of 2",
  			ubi->min_io_size);
  		return -EINVAL;
  	}
  
  	ubi_assert(ubi->hdrs_min_io_size > 0);
  	ubi_assert(ubi->hdrs_min_io_size <= ubi->min_io_size);
  	ubi_assert(ubi->min_io_size % ubi->hdrs_min_io_size == 0);
  
  	/* Calculate default aligned sizes of EC and VID headers */
  	ubi->ec_hdr_alsize = ALIGN(UBI_EC_HDR_SIZE, ubi->hdrs_min_io_size);
  	ubi->vid_hdr_alsize = ALIGN(UBI_VID_HDR_SIZE, ubi->hdrs_min_io_size);
  
  	dbg_msg("min_io_size      %d", ubi->min_io_size);
  	dbg_msg("hdrs_min_io_size %d", ubi->hdrs_min_io_size);
  	dbg_msg("ec_hdr_alsize    %d", ubi->ec_hdr_alsize);
  	dbg_msg("vid_hdr_alsize   %d", ubi->vid_hdr_alsize);
  
  	if (ubi->vid_hdr_offset == 0)
  		/* Default offset */
  		ubi->vid_hdr_offset = ubi->vid_hdr_aloffset =
  				      ubi->ec_hdr_alsize;
  	else {
  		ubi->vid_hdr_aloffset = ubi->vid_hdr_offset &
  						~(ubi->hdrs_min_io_size - 1);
  		ubi->vid_hdr_shift = ubi->vid_hdr_offset -
  						ubi->vid_hdr_aloffset;
  	}
  
  	/* Similar for the data offset */
  	ubi->leb_start = ubi->vid_hdr_offset + UBI_EC_HDR_SIZE;
  	ubi->leb_start = ALIGN(ubi->leb_start, ubi->min_io_size);
  
  	dbg_msg("vid_hdr_offset   %d", ubi->vid_hdr_offset);
  	dbg_msg("vid_hdr_aloffset %d", ubi->vid_hdr_aloffset);
  	dbg_msg("vid_hdr_shift    %d", ubi->vid_hdr_shift);
  	dbg_msg("leb_start        %d", ubi->leb_start);
  
  	/* The shift must be aligned to 32-bit boundary */
  	if (ubi->vid_hdr_shift % 4) {
  		ubi_err("unaligned VID header shift %d",
  			ubi->vid_hdr_shift);
  		return -EINVAL;
  	}
  
  	/* Check sanity */
  	if (ubi->vid_hdr_offset < UBI_EC_HDR_SIZE ||
  	    ubi->leb_start < ubi->vid_hdr_offset + UBI_VID_HDR_SIZE ||
  	    ubi->leb_start > ubi->peb_size - UBI_VID_HDR_SIZE ||
  	    ubi->leb_start & (ubi->min_io_size - 1)) {
  		ubi_err("bad VID header (%d) or data offsets (%d)",
  			ubi->vid_hdr_offset, ubi->leb_start);
  		return -EINVAL;
  	}
  
  	/*
  	 * It may happen that EC and VID headers are situated in one minimal
  	 * I/O unit. In this case we can only accept this UBI image in
  	 * read-only mode.
  	 */
  	if (ubi->vid_hdr_offset + UBI_VID_HDR_SIZE <= ubi->hdrs_min_io_size) {
  		ubi_warn("EC and VID headers are in the same minimal I/O unit, "
  			 "switch to read-only mode");
  		ubi->ro_mode = 1;
  	}
  
  	ubi->leb_size = ubi->peb_size - ubi->leb_start;
  
  	if (!(ubi->mtd->flags & MTD_WRITEABLE)) {
  		ubi_msg("MTD device %d is write-protected, attach in "
  			"read-only mode", ubi->mtd->index);
  		ubi->ro_mode = 1;
  	}
  
  	ubi_msg("physical eraseblock size:   %d bytes (%d KiB)",
  		ubi->peb_size, ubi->peb_size >> 10);
  	ubi_msg("logical eraseblock size:    %d bytes", ubi->leb_size);
  	ubi_msg("smallest flash I/O unit:    %d", ubi->min_io_size);
  	if (ubi->hdrs_min_io_size != ubi->min_io_size)
  		ubi_msg("sub-page size:              %d",
  			ubi->hdrs_min_io_size);
  	ubi_msg("VID header offset:          %d (aligned %d)",
  		ubi->vid_hdr_offset, ubi->vid_hdr_aloffset);
  	ubi_msg("data offset:                %d", ubi->leb_start);
  
  	/*
  	 * Note, ideally, we have to initialize ubi->bad_peb_count here. But
  	 * unfortunately, MTD does not provide this information. We should loop
  	 * over all physical eraseblocks and invoke mtd->block_is_bad() for
  	 * each physical eraseblock. So, we skip ubi->bad_peb_count
  	 * uninitialized and initialize it after scanning.
  	 */
  
  	return 0;
  }
  
  /**
   * autoresize - re-size the volume which has the "auto-resize" flag set.
   * @ubi: UBI device description object
   * @vol_id: ID of the volume to re-size
   *
   * This function re-sizes the volume marked by the @UBI_VTBL_AUTORESIZE_FLG in
   * the volume table to the largest possible size. See comments in ubi-header.h
   * for more description of the flag. Returns zero in case of success and a
   * negative error code in case of failure.
   */
  static int autoresize(struct ubi_device *ubi, int vol_id)
  {
  	struct ubi_volume_desc desc;
  	struct ubi_volume *vol = ubi->volumes[vol_id];
  	int err, old_reserved_pebs = vol->reserved_pebs;
  
  	/*
  	 * Clear the auto-resize flag in the volume in-memory copy of the
  	 * volume table, and 'ubi_resize_volume()' will propogate this change
  	 * to the flash.
  	 */
  	ubi->vtbl[vol_id].flags &= ~UBI_VTBL_AUTORESIZE_FLG;
  
  	if (ubi->avail_pebs == 0) {
  		struct ubi_vtbl_record vtbl_rec;
  
  		/*
  		 * No avalilable PEBs to re-size the volume, clear the flag on
  		 * flash and exit.
  		 */
  		memcpy(&vtbl_rec, &ubi->vtbl[vol_id],
  		       sizeof(struct ubi_vtbl_record));
  		err = ubi_change_vtbl_record(ubi, vol_id, &vtbl_rec);
  		if (err)
  			ubi_err("cannot clean auto-resize flag for volume %d",
  				vol_id);
  	} else {
  		desc.vol = vol;
  		err = ubi_resize_volume(&desc,
  					old_reserved_pebs + ubi->avail_pebs);
  		if (err)
  			ubi_err("cannot auto-resize volume %d", vol_id);
  	}
  
  	if (err)
  		return err;
  
  	ubi_msg("volume %d (\"%s\") re-sized from %d to %d LEBs", vol_id,
  		vol->name, old_reserved_pebs, vol->reserved_pebs);
  	return 0;
  }
  
  /**
   * ubi_attach_mtd_dev - attach an MTD device.
   * @mtd_dev: MTD device description object
   * @ubi_num: number to assign to the new UBI device
   * @vid_hdr_offset: VID header offset
   *
   * This function attaches MTD device @mtd_dev to UBI and assign @ubi_num number
   * to the newly created UBI device, unless @ubi_num is %UBI_DEV_NUM_AUTO, in
   * which case this function finds a vacant device nubert and assings it
   * automatically. Returns the new UBI device number in case of success and a
   * negative error code in case of failure.
   *
   * Note, the invocations of this function has to be serialized by the
   * @ubi_devices_mutex.
   */
  int ubi_attach_mtd_dev(struct mtd_info *mtd, int ubi_num, int vid_hdr_offset)
  {
  	struct ubi_device *ubi;
  	int i, err;
  
  	/*
  	 * Check if we already have the same MTD device attached.
  	 *
  	 * Note, this function assumes that UBI devices creations and deletions
  	 * are serialized, so it does not take the &ubi_devices_lock.
  	 */
  	for (i = 0; i < UBI_MAX_DEVICES; i++) {
  		ubi = ubi_devices[i];
  		if (ubi && mtd->index == ubi->mtd->index) {
  			dbg_err("mtd%d is already attached to ubi%d",
  				mtd->index, i);
  			return -EEXIST;
  		}
  	}
  
  	/*
  	 * Make sure this MTD device is not emulated on top of an UBI volume
  	 * already. Well, generally this recursion works fine, but there are
  	 * different problems like the UBI module takes a reference to itself
  	 * by attaching (and thus, opening) the emulated MTD device. This
  	 * results in inability to unload the module. And in general it makes
  	 * no sense to attach emulated MTD devices, so we prohibit this.
  	 */
  	if (mtd->type == MTD_UBIVOLUME) {
  		ubi_err("refuse attaching mtd%d - it is already emulated on "
  			"top of UBI", mtd->index);
  		return -EINVAL;
  	}
  
  	if (ubi_num == UBI_DEV_NUM_AUTO) {
  		/* Search for an empty slot in the @ubi_devices array */
  		for (ubi_num = 0; ubi_num < UBI_MAX_DEVICES; ubi_num++)
  			if (!ubi_devices[ubi_num])
  				break;
  		if (ubi_num == UBI_MAX_DEVICES) {
  			dbg_err("only %d UBI devices may be created", UBI_MAX_DEVICES);
  			return -ENFILE;
  		}
  	} else {
  		if (ubi_num >= UBI_MAX_DEVICES)
  			return -EINVAL;
  
  		/* Make sure ubi_num is not busy */
  		if (ubi_devices[ubi_num]) {
  			dbg_err("ubi%d already exists", ubi_num);
  			return -EEXIST;
  		}
  	}
  
  	ubi = kzalloc(sizeof(struct ubi_device), GFP_KERNEL);
  	if (!ubi)
  		return -ENOMEM;
  
  	ubi->mtd = mtd;
  	ubi->ubi_num = ubi_num;
  	ubi->vid_hdr_offset = vid_hdr_offset;
  	ubi->autoresize_vol_id = -1;
  
  	mutex_init(&ubi->buf_mutex);
  	mutex_init(&ubi->ckvol_mutex);
  	mutex_init(&ubi->volumes_mutex);
  	spin_lock_init(&ubi->volumes_lock);
  
  	ubi_msg("attaching mtd%d to ubi%d", mtd->index, ubi_num);
  
  	err = io_init(ubi);
  	if (err)
  		goto out_free;
  
  	err = -ENOMEM;
  	ubi->peb_buf1 = vmalloc(ubi->peb_size);
  	if (!ubi->peb_buf1)
  		goto out_free;
  
  	ubi->peb_buf2 = vmalloc(ubi->peb_size);
  	if (!ubi->peb_buf2)
  		goto out_free;
  
  #ifdef CONFIG_MTD_UBI_DEBUG
  	mutex_init(&ubi->dbg_buf_mutex);
  	ubi->dbg_peb_buf = vmalloc(ubi->peb_size);
  	if (!ubi->dbg_peb_buf)
  		goto out_free;
  #endif
  
  	err = attach_by_scanning(ubi);
  	if (err) {
  		dbg_err("failed to attach by scanning, error %d", err);
  		goto out_free;
  	}
  
  	if (ubi->autoresize_vol_id != -1) {
  		err = autoresize(ubi, ubi->autoresize_vol_id);
  		if (err)
  			goto out_detach;
  	}
  
  	err = uif_init(ubi);
  	if (err)
  		goto out_detach;
  
  	ubi->bgt_thread = kthread_create(ubi_thread, ubi, ubi->bgt_name);
  	if (IS_ERR(ubi->bgt_thread)) {
  		err = PTR_ERR(ubi->bgt_thread);
  		ubi_err("cannot spawn \"%s\", error %d", ubi->bgt_name,
  			err);
  		goto out_uif;
  	}
  
  	ubi_msg("attached mtd%d to ubi%d", mtd->index, ubi_num);
  	ubi_msg("MTD device name:            \"%s\"", mtd->name);
  	ubi_msg("MTD device size:            %llu MiB", ubi->flash_size >> 20);
  	ubi_msg("number of good PEBs:        %d", ubi->good_peb_count);
  	ubi_msg("number of bad PEBs:         %d", ubi->bad_peb_count);
  	ubi_msg("max. allowed volumes:       %d", ubi->vtbl_slots);
  	ubi_msg("wear-leveling threshold:    %d", CONFIG_MTD_UBI_WL_THRESHOLD);
  	ubi_msg("number of internal volumes: %d", UBI_INT_VOL_COUNT);
  	ubi_msg("number of user volumes:     %d",
  		ubi->vol_count - UBI_INT_VOL_COUNT);
  	ubi_msg("available PEBs:             %d", ubi->avail_pebs);
  	ubi_msg("total number of reserved PEBs: %d", ubi->rsvd_pebs);
  	ubi_msg("number of PEBs reserved for bad PEB handling: %d",
  		ubi->beb_rsvd_pebs);
  	ubi_msg("max/mean erase counter: %d/%d", ubi->max_ec, ubi->mean_ec);
  
  	/* Enable the background thread */
  	if (!DBG_DISABLE_BGT) {
  		ubi->thread_enabled = 1;
  		wake_up_process(ubi->bgt_thread);
  	}
  
  	ubi_devices[ubi_num] = ubi;
  	return ubi_num;
  
  out_uif:
  	uif_close(ubi);
  out_detach:
  	ubi_eba_close(ubi);
  	ubi_wl_close(ubi);
  	vfree(ubi->vtbl);
  out_free:
  	vfree(ubi->peb_buf1);
  	vfree(ubi->peb_buf2);
  #ifdef CONFIG_MTD_UBI_DEBUG
  	vfree(ubi->dbg_peb_buf);
  #endif
  	kfree(ubi);
  	return err;
  }
  
  /**
   * ubi_detach_mtd_dev - detach an MTD device.
   * @ubi_num: UBI device number to detach from
   * @anyway: detach MTD even if device reference count is not zero
   *
   * This function destroys an UBI device number @ubi_num and detaches the
   * underlying MTD device. Returns zero in case of success and %-EBUSY if the
   * UBI device is busy and cannot be destroyed, and %-EINVAL if it does not
   * exist.
   *
   * Note, the invocations of this function has to be serialized by the
   * @ubi_devices_mutex.
   */
  int ubi_detach_mtd_dev(int ubi_num, int anyway)
  {
  	struct ubi_device *ubi;
  
  	if (ubi_num < 0 || ubi_num >= UBI_MAX_DEVICES)
  		return -EINVAL;
  
  	spin_lock(&ubi_devices_lock);
  	ubi = ubi_devices[ubi_num];
  	if (!ubi) {
  		spin_unlock(&ubi_devices_lock);
  		return -EINVAL;
  	}
  
  	if (ubi->ref_count) {
  		if (!anyway) {
  			spin_unlock(&ubi_devices_lock);
  			return -EBUSY;
  		}
  		/* This may only happen if there is a bug */
  		ubi_err("%s reference count %d, destroy anyway",
  			ubi->ubi_name, ubi->ref_count);
  	}
  	ubi_devices[ubi_num] = NULL;
  	spin_unlock(&ubi_devices_lock);
  
  	ubi_assert(ubi_num == ubi->ubi_num);
  	dbg_msg("detaching mtd%d from ubi%d", ubi->mtd->index, ubi_num);
  
  	/*
  	 * Before freeing anything, we have to stop the background thread to
  	 * prevent it from doing anything on this device while we are freeing.
  	 */
  	if (ubi->bgt_thread)
  		kthread_stop(ubi->bgt_thread);
  
  	uif_close(ubi);
  	ubi_eba_close(ubi);
  	ubi_wl_close(ubi);
  	vfree(ubi->vtbl);
  	put_mtd_device(ubi->mtd);
  	vfree(ubi->peb_buf1);
  	vfree(ubi->peb_buf2);
  #ifdef CONFIG_MTD_UBI_DEBUG
  	vfree(ubi->dbg_peb_buf);
  #endif
  	ubi_msg("mtd%d is detached from ubi%d", ubi->mtd->index, ubi->ubi_num);
  	kfree(ubi);
  	return 0;
  }
  
  /**
   * find_mtd_device - open an MTD device by its name or number.
   * @mtd_dev: name or number of the device
   *
   * This function tries to open and MTD device described by @mtd_dev string,
   * which is first treated as an ASCII number, and if it is not true, it is
   * treated as MTD device name. Returns MTD device description object in case of
   * success and a negative error code in case of failure.
   */
  static struct mtd_info * __init open_mtd_device(const char *mtd_dev)
  {
  	struct mtd_info *mtd;
  	int mtd_num;
  	char *endp;
  
  	mtd_num = simple_strtoul(mtd_dev, &endp, 0);
  	if (*endp != '\0' || mtd_dev == endp) {
  		/*
  		 * This does not look like an ASCII integer, probably this is
  		 * MTD device name.
  		 */
  		mtd = get_mtd_device_nm(mtd_dev);
  	} else
  		mtd = get_mtd_device(NULL, mtd_num);
  
  	return mtd;
  }
  
  int __init ubi_init(void)
  {
  	int err, i, k;
  
  	/* Ensure that EC and VID headers have correct size */
  	BUILD_BUG_ON(sizeof(struct ubi_ec_hdr) != 64);
  	BUILD_BUG_ON(sizeof(struct ubi_vid_hdr) != 64);
  
  	if (mtd_devs > UBI_MAX_DEVICES) {
  		ubi_err("too many MTD devices, maximum is %d", UBI_MAX_DEVICES);
  		return -EINVAL;
  	}
  
  	/* Create base sysfs directory and sysfs files */
  	ubi_class = class_create(THIS_MODULE, UBI_NAME_STR);
  	if (IS_ERR(ubi_class)) {
  		err = PTR_ERR(ubi_class);
  		ubi_err("cannot create UBI class");
  		goto out;
  	}
  
  	err = class_create_file(ubi_class, &ubi_version);
  	if (err) {
  		ubi_err("cannot create sysfs file");
  		goto out_class;
  	}
  
  	err = misc_register(&ubi_ctrl_cdev);
  	if (err) {
  		ubi_err("cannot register device");
  		goto out_version;
  	}
  
  #ifdef UBI_LINUX
  	ubi_wl_entry_slab = kmem_cache_create("ubi_wl_entry_slab",
  					      sizeof(struct ubi_wl_entry),
  					      0, 0, NULL);
  	if (!ubi_wl_entry_slab)
  		goto out_dev_unreg;
  #endif
  
  	/* Attach MTD devices */
  	for (i = 0; i < mtd_devs; i++) {
  		struct mtd_dev_param *p = &mtd_dev_param[i];
  		struct mtd_info *mtd;
  
  		cond_resched();
  
  		mtd = open_mtd_device(p->name);
  		if (IS_ERR(mtd)) {
  			err = PTR_ERR(mtd);
  			goto out_detach;
  		}
  
  		mutex_lock(&ubi_devices_mutex);
  		err = ubi_attach_mtd_dev(mtd, UBI_DEV_NUM_AUTO,
  					 p->vid_hdr_offs);
  		mutex_unlock(&ubi_devices_mutex);
  		if (err < 0) {
  			put_mtd_device(mtd);
  			ubi_err("cannot attach mtd%d", mtd->index);
  			goto out_detach;
  		}
  	}
  
  	return 0;
  
  out_detach:
  	for (k = 0; k < i; k++)
  		if (ubi_devices[k]) {
  			mutex_lock(&ubi_devices_mutex);
  			ubi_detach_mtd_dev(ubi_devices[k]->ubi_num, 1);
  			mutex_unlock(&ubi_devices_mutex);
  		}
  #ifdef UBI_LINUX
  	kmem_cache_destroy(ubi_wl_entry_slab);
  out_dev_unreg:
  #endif
  	misc_deregister(&ubi_ctrl_cdev);
  out_version:
  	class_remove_file(ubi_class, &ubi_version);
  out_class:
  	class_destroy(ubi_class);
  out:
  	ubi_err("UBI error: cannot initialize UBI, error %d", err);
  	return err;
  }
  module_init(ubi_init);
  
  void __exit ubi_exit(void)
  {
  	int i;
  
  	for (i = 0; i < UBI_MAX_DEVICES; i++)
  		if (ubi_devices[i]) {
  			mutex_lock(&ubi_devices_mutex);
  			ubi_detach_mtd_dev(ubi_devices[i]->ubi_num, 1);
  			mutex_unlock(&ubi_devices_mutex);
  		}
  	kmem_cache_destroy(ubi_wl_entry_slab);
  	misc_deregister(&ubi_ctrl_cdev);
  	class_remove_file(ubi_class, &ubi_version);
  	class_destroy(ubi_class);
  	mtd_devs = 0;
  }
  module_exit(ubi_exit);
  
  /**
   * bytes_str_to_int - convert a string representing number of bytes to an
   * integer.
   * @str: the string to convert
   *
   * This function returns positive resulting integer in case of success and a
   * negative error code in case of failure.
   */
  static int __init bytes_str_to_int(const char *str)
  {
  	char *endp;
  	unsigned long result;
  
  	result = simple_strtoul(str, &endp, 0);
  	if (str == endp || result < 0) {
  		printk(KERN_ERR "UBI error: incorrect bytes count: \"%s\"\n",
  		       str);
  		return -EINVAL;
  	}
  
  	switch (*endp) {
  	case 'G':
  		result *= 1024;
  	case 'M':
  		result *= 1024;
  	case 'K':
  		result *= 1024;
  		if (endp[1] == 'i' && endp[2] == 'B')
  			endp += 2;
  	case '\0':
  		break;
  	default:
  		printk(KERN_ERR "UBI error: incorrect bytes count: \"%s\"\n",
  		       str);
  		return -EINVAL;
  	}
  
  	return result;
  }
  
  /**
   * ubi_mtd_param_parse - parse the 'mtd=' UBI parameter.
   * @val: the parameter value to parse
   * @kp: not used
   *
   * This function returns zero in case of success and a negative error code in
   * case of error.
   */
  int __init ubi_mtd_param_parse(const char *val, struct kernel_param *kp)
  {
  	int i, len;
  	struct mtd_dev_param *p;
  	char buf[MTD_PARAM_LEN_MAX];
  	char *pbuf = &buf[0];
  	char *tokens[2] = {NULL, NULL};
  
  	if (!val)
  		return -EINVAL;
  
  	if (mtd_devs == UBI_MAX_DEVICES) {
  		printk(KERN_ERR "UBI error: too many parameters, max. is %d\n",
  		       UBI_MAX_DEVICES);
  		return -EINVAL;
  	}
  
  	len = strnlen(val, MTD_PARAM_LEN_MAX);
  	if (len == MTD_PARAM_LEN_MAX) {
  		printk(KERN_ERR "UBI error: parameter \"%s\" is too long, "
  		       "max. is %d\n", val, MTD_PARAM_LEN_MAX);
  		return -EINVAL;
  	}
  
  	if (len == 0) {
  		printk(KERN_WARNING "UBI warning: empty 'mtd=' parameter - "
  		       "ignored\n");
  		return 0;
  	}
  
  	strcpy(buf, val);
  
  	/* Get rid of the final newline */
  	if (buf[len - 1] == '\n')
  		buf[len - 1] = '\0';
  
  	for (i = 0; i < 2; i++)
  		tokens[i] = strsep(&pbuf, ",");
  
  	if (pbuf) {
  		printk(KERN_ERR "UBI error: too many arguments at \"%s\"\n",
  		       val);
  		return -EINVAL;
  	}
  
  	p = &mtd_dev_param[mtd_devs];
  	strcpy(&p->name[0], tokens[0]);
  
  	if (tokens[1])
  		p->vid_hdr_offs = bytes_str_to_int(tokens[1]);
  
  	if (p->vid_hdr_offs < 0)
  		return p->vid_hdr_offs;
  
  	mtd_devs += 1;
  	return 0;
  }
  
  module_param_call(mtd, ubi_mtd_param_parse, NULL, NULL, 000);
  MODULE_PARM_DESC(mtd, "MTD devices to attach. Parameter format: "
  		      "mtd=<name|num>[,<vid_hdr_offs>].\n"
  		      "Multiple \"mtd\" parameters may be specified.\n"
  		      "MTD devices may be specified by their number or name.\n"
  		      "Optional \"vid_hdr_offs\" parameter specifies UBI VID "
  		      "header position and data starting position to be used "
  		      "by UBI.\n"
  		      "Example: mtd=content,1984 mtd=4 - attach MTD device"
  		      "with name \"content\" using VID header offset 1984, and "
  		      "MTD device number 4 with default VID header offset.");
  
  MODULE_VERSION(__stringify(UBI_VERSION));
  MODULE_DESCRIPTION("UBI - Unsorted Block Images");
  MODULE_AUTHOR("Artem Bityutskiy");
  MODULE_LICENSE("GPL");
  