package/system/mtd/src/linksys_bootcount.c

   1 /*
   2  * Linksys boot counter reset code for mtd
   3  *
   4  * Copyright (C) 2013 Jonas Gorski <jogo@openwrt.org>
   5  *
   6  * This program is free software; you can redistribute it and/or
   7  * modify it under the terms of the GNU General Public License v2
   8  * as published by the Free Software Foundation.
   9  *
  10  * This program is distributed in the hope that it will be useful,
  11  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  12  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13  * GNU General Public License for more details.
  14  *
  15  * You should have received a copy of the GNU General Public License
  16  * along with this program; if not, write to the Free Software
  17  * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
  18  *
  19  */
  20
  21 #include <stdio.h>
  22 #include <stdlib.h>
  23 #include <stddef.h>
  24 #include <unistd.h>
  25 #include <fcntl.h>
  26 #include <sys/mman.h>
  27 #include <sys/stat.h>
  28 #include <endian.h>
  29 #include <string.h>
  30 #include <errno.h>
  31
  32 #include <sys/ioctl.h>
  33 #include <mtd/mtd-user.h>
  34
  35 #include "mtd.h"
  36
  37 #define BOOTCOUNT_MAGIC 0x20110811
  38
  39 struct bootcounter {
  40         uint32_t magic;
  41         uint32_t count;
  42         uint32_t checksum;
  43 };
  44
  45 static char page[2048];
  46
  47 int mtd_resetbc(const char *mtd)
  48 {
  49         struct mtd_info_user mtd_info;
  50         struct bootcounter *curr = (struct bootcounter *)page;
  51         unsigned int i;
  52         int last_count = 0;
  53         int num_bc;
  54         int fd;
  55         int ret;
  56
  57         fd = mtd_check_open(mtd);
  58
  59         if (ioctl(fd, MEMGETINFO, &mtd_info) < 0) {
  60                 fprintf(stderr, "failed to get mtd info!\n");
  61                 return -1;
  62         }
  63
  64         num_bc = mtd_info.size / mtd_info.writesize;
  65
  66         for (i = 0; i < num_bc; i++) {
  67                 pread(fd, curr, sizeof(*curr), i * mtd_info.writesize);
  68
  69                 if (curr->magic != BOOTCOUNT_MAGIC && curr->magic != 0xffffffff) {
  70                         fprintf(stderr, "unexpected magic %08x, bailing out\n", curr->magic);
  71                         goto out;
  72                 }
  73
  74                 if (curr->magic == 0xffffffff)
  75                         break;
  76
  77                 last_count = curr->count;
  78         }
  79
  80         /* no need to do writes when last boot count is already 0 */
  81         if (last_count == 0)
  82                 goto out;
  83
  84
  85         if (i == num_bc) {
  86                 struct erase_info_user erase_info;
  87                 erase_info.start = 0;
  88                 erase_info.length = mtd_info.size;
  89
  90                 /* erase block */
  91                 ret = ioctl(fd, MEMERASE, &erase_info);
  92                 if (ret < 0) {
  93                         fprintf(stderr, "failed to erase block: %i\n", ret);
  94                         return -1;
  95                 }
  96
  97                 i = 0;
  98         }
  99
 100         memset(curr, 0xff, mtd_info.writesize);
 101
 102         curr->magic = BOOTCOUNT_MAGIC;
 103         curr->count = 0;
 104         curr->checksum = BOOTCOUNT_MAGIC;
 105
 106         ret = pwrite(fd, curr, mtd_info.writesize, i * mtd_info.writesize);
 107         if (ret < 0)
 108                 fprintf(stderr, "failed to write: %i\n", ret);
 109         sync();
 110 out:
 111         close(fd);
 112
 113         return 0;
 114 }