release/src-rt-6.x.4708/linux/linux-2.6.36/drivers/mtd/ubi/misc.c

   1 /*
   2  * Copyright (c) International Business Machines Corp., 2006
   3  *
   4  * This program is free software; you can redistribute it and/or modify
   5  * it under the terms of the GNU General Public License as published by
   6  * the Free Software Foundation; either version 2 of the License, or
   7  * (at your option) any later version.
   8  *
   9  * This program is distributed in the hope that it will be useful,
  10  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See
  12  * the GNU General Public License for more details.
  13  *
  14  * You should have received a copy of the GNU General Public License
  15  * along with this program; if not, write to the Free Software
  16  * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
  17  *
  18  * Author: Artem Bityutskiy (Битюцкий Артём)
  19  */
  20
  21 /* Here we keep miscellaneous functions which are used all over the UBI code */
  22
  23 #include "ubi.h"
  24
  25 /**
  26  * calc_data_len - calculate how much real data is stored in a buffer.
  27  * @ubi: UBI device description object
  28  * @buf: a buffer with the contents of the physical eraseblock
  29  * @length: the buffer length
  30  *
  31  * This function calculates how much "real data" is stored in @buf and returnes
  32  * the length. Continuous 0xFF bytes at the end of the buffer are not
  33  * considered as "real data".
  34  */
  35 int ubi_calc_data_len(const struct ubi_device *ubi, const void *buf,
  36                       int length)
  37 {
  38         int i;
  39
  40         ubi_assert(!(length & (ubi->min_io_size - 1)));
  41
  42         for (i = length - 1; i >= 0; i--)
  43                 if (((const uint8_t *)buf)[i] != 0xFF)
  44                         break;
  45
  46         /* The resulting length must be aligned to the minimum flash I/O size */
  47         length = ALIGN(i + 1, ubi->min_io_size);
  48         return length;
  49 }
  50
  51 /**
  52  * ubi_check_volume - check the contents of a static volume.
  53  * @ubi: UBI device description object
  54  * @vol_id: ID of the volume to check
  55  *
  56  * This function checks if static volume @vol_id is corrupted by fully reading
  57  * it and checking data CRC. This function returns %0 if the volume is not
  58  * corrupted, %1 if it is corrupted and a negative error code in case of
  59  * failure. Dynamic volumes are not checked and zero is returned immediately.
  60  */
  61 int ubi_check_volume(struct ubi_device *ubi, int vol_id)
  62 {
  63         void *buf;
  64         int err = 0, i;
  65         struct ubi_volume *vol = ubi->volumes[vol_id];
  66
  67         if (vol->vol_type != UBI_STATIC_VOLUME)
  68                 return 0;
  69
  70         buf = vmalloc(vol->usable_leb_size);
  71         if (!buf)
  72                 return -ENOMEM;
  73
  74         for (i = 0; i < vol->used_ebs; i++) {
  75                 int size;
  76
  77                 if (i == vol->used_ebs - 1)
  78                         size = vol->last_eb_bytes;
  79                 else
  80                         size = vol->usable_leb_size;
  81
  82                 err = ubi_eba_read_leb(ubi, vol, i, buf, 0, size, 1);
  83                 if (err) {
  84                         if (err == -EBADMSG)
  85                                 err = 1;
  86                         break;
  87                 }
  88         }
  89
  90         vfree(buf);
  91         return err;
  92 }
  93
  94 /**
  95  * ubi_calculate_rsvd_pool - calculate how many PEBs must be reserved for bad
  96  * eraseblock handling.
  97  * @ubi: UBI device description object
  98  */
  99 void ubi_calculate_reserved(struct ubi_device *ubi)
 100 {
 101         ubi->beb_rsvd_level = ubi->good_peb_count/100;
 102         ubi->beb_rsvd_level *= CONFIG_MTD_UBI_BEB_RESERVE;
 103         if (ubi->beb_rsvd_level < MIN_RESEVED_PEBS)
 104                 ubi->beb_rsvd_level = MIN_RESEVED_PEBS;
 105 }