/*
   * Copyright (c) International Business Machines Corp., 2006
   *
   * 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)
   */
  
  /* Here we keep miscellaneous functions which are used all over the UBI code */
  
  #include "ubi.h"
  
  /**
   * calc_data_len - calculate how much real data is stored in a buffer.
   * @ubi: UBI device description object
   * @buf: a buffer with the contents of the physical eraseblock
   * @length: the buffer length
   *
   * This function calculates how much "real data" is stored in @buf and returnes
   * the length. Continuous 0xFF bytes at the end of the buffer are not
   * considered as "real data".
   */
  int ubi_calc_data_len(const struct ubi_device *ubi, const void *buf,
  		      int length)
  {
  	int i;
  
  	ubi_assert(!(length & (ubi->min_io_size - 1)));
  
  	for (i = length - 1; i >= 0; i--)
  		if (((const uint8_t *)buf)[i] != 0xFF)
  			break;
  
  	/* The resulting length must be aligned to the minimum flash I/O size */
  	length = ALIGN(i + 1, ubi->min_io_size);
  	return length;
  }
  
  /**
   * ubi_check_volume - check the contents of a static volume.
   * @ubi: UBI device description object
   * @vol_id: ID of the volume to check
   *
   * This function checks if static volume @vol_id is corrupted by fully reading
   * it and checking data CRC. This function returns %0 if the volume is not
   * corrupted, %1 if it is corrupted and a negative error code in case of
   * failure. Dynamic volumes are not checked and zero is returned immediately.
   */
  int ubi_check_volume(struct ubi_device *ubi, int vol_id)
  {
  	void *buf;
  	int err = 0, i;
  	struct ubi_volume *vol = ubi->volumes[vol_id];
  
  	if (vol->vol_type != UBI_STATIC_VOLUME)
  		return 0;
  
  	buf = vmalloc(vol->usable_leb_size);
  	if (!buf)
  		return -ENOMEM;
  
  	for (i = 0; i < vol->used_ebs; i++) {
  		int size;
  
  		if (i == vol->used_ebs - 1)
  			size = vol->last_eb_bytes;
  		else
  			size = vol->usable_leb_size;
  
  		err = ubi_eba_read_leb(ubi, vol, i, buf, 0, size, 1);
  		if (err) {
  			if (mtd_is_eccerr(err))
  				err = 1;
  			break;
  		}
  	}
  
  	vfree(buf);
  	return err;
  }
  
  /**
   * ubi_update_reserved - update bad eraseblock handling accounting data.
   * @ubi: UBI device description object
   *
   * This function calculates the gap between current number of PEBs reserved for
   * bad eraseblock handling and the required level of PEBs that must be
   * reserved, and if necessary, reserves more PEBs to fill that gap, according
   * to availability. Should be called with ubi->volumes_lock held.
   */
  void ubi_update_reserved(struct ubi_device *ubi)
  {
  	int need = ubi->beb_rsvd_level - ubi->beb_rsvd_pebs;
  
  	if (need <= 0 || ubi->avail_pebs == 0)
  		return;
  
  	need = min_t(int, need, ubi->avail_pebs);
  	ubi->avail_pebs -= need;
  	ubi->rsvd_pebs += need;
  	ubi->beb_rsvd_pebs += need;
  	ubi_msg("reserved more %d PEBs for bad PEB handling", need);
  }
  
  /**
   * ubi_calculate_reserved - calculate how many PEBs must be reserved for bad
   * eraseblock handling.
   * @ubi: UBI device description object
   */
  void ubi_calculate_reserved(struct ubi_device *ubi)
  {
  	/*
  	 * Calculate the actual number of PEBs currently needed to be reserved
  	 * for future bad eraseblock handling.
  	 */
  	ubi->beb_rsvd_level = ubi->bad_peb_limit - ubi->bad_peb_count;
  	if (ubi->beb_rsvd_level < 0) {
  		ubi->beb_rsvd_level = 0;
  		ubi_warn("number of bad PEBs (%d) is above the expected limit (%d), not reserving any PEBs for bad PEB handling, will use available PEBs (if any)",
  			 ubi->bad_peb_count, ubi->bad_peb_limit);
  	}
  }
  
  /**
   * ubi_check_pattern - check if buffer contains only a certain byte pattern.
   * @buf: buffer to check
   * @patt: the pattern to check
   * @size: buffer size in bytes
   *
   * This function returns %1 in there are only @patt bytes in @buf, and %0 if
   * something else was also found.
   */
  int ubi_check_pattern(const void *buf, uint8_t patt, int size)
  {
  	int i;
  
  	for (i = 0; i < size; i++)
  		if (((const uint8_t *)buf)[i] != patt)
  			return 0;
  	return 1;
  }