yaffs_fileem.c

   1 /*
   2  * YAFFS: Yet another FFS. A NAND-flash specific file system.
   3  * yaffs_fileem.c  NAND emulation on top of files
   4  *
   5  * Copyright (C) 2002 Aleph One Ltd.
   6  *   for Toby Churchill Ltd and Brightstar Engineering
   7  *
   8  * Created by Charles Manning <charles@aleph1.co.uk>
   9  *
  10  * This program is free software; you can redistribute it and/or modify
  11  * it under the terms of the GNU General Public License version 2 as
  12  * published by the Free Software Foundation.
  13  *
  14  */
  15  //yaffs_fileem.c
  16
  17 #include "yaffs_fileem.h"
  18 #include "yaffs_guts.h"
  19 #include "yaffsinterface.h"
  20
  21 #include <stdio.h>
  22 #include <stdlib.h>
  23 #include <unistd.h>
  24 #include <sys/types.h>
  25 #include <sys/stat.h>
  26 #include <fcntl.h>
  27 #include <string.h>
  28
  29 #define FILE_SIZE_IN_MEG 32
  30
  31 #define BLOCK_SIZE (32 * 528)
  32 #define BLOCKS_PER_MEG ((1024*1024)/(32 * 512))
  33 #define FILE_SIZE_IN_BLOCKS (FILE_SIZE_IN_MEG * BLOCKS_PER_MEG)
  34 #define FILE_SIZE_IN_BYTES (FILE_SIZE_IN_BLOCKS * BLOCK_SIZE)
  35
  36
  37 static int h;
  38 static __u8 ffChunk[528];
  39
  40 static int eraseDisplayEnabled;
  41
  42 static int markedBadBlocks[] = { 1, 4, -1};
  43
  44 static int IsAMarkedBadBlock(int blk)
  45 {
  46         int *m = markedBadBlocks;
  47
  48         while(*m >= 0)
  49         {
  50                 if(*m == blk) return 1;
  51                 m++;
  52         }
  53         return 0;
  54 }
  55
  56
  57 static __u8 yaffs_WriteFailCorruption(int chunkInNAND)
  58 {
  59         switch(chunkInNAND)
  60         {
  61                 case 2000:
  62                 case 2003:
  63                 case 3000:
  64                 case 3001:
  65                                         return 3;// ding two bits
  66                 case 2001:
  67                 case 3003:
  68                 case 3004:
  69                 case 3005:
  70                 case 3006:
  71                 case 3007:  return 1;// ding one bit
  72
  73                 default: return 0;
  74
  75         }
  76 }
  77
  78 static void yaffs_ModifyWriteData(int chunkInNAND,__u8 *data)
  79 {
  80         if(data)
  81         {
  82                 *data ^= yaffs_WriteFailCorruption(chunkInNAND);
  83         }
  84 }
  85
  86 static __u8 yaffs_ReadFailCorruption(int chunkInNAND)
  87 {
  88         switch(chunkInNAND)
  89         {
  90                 case 500:
  91                                         return 3;// ding two bits
  92                 case 700:
  93                 case 750:
  94                                         return 1;// ding one bit
  95
  96                 default: return 0;
  97
  98         }
  99 }
 100
 101 static void yaffs_ModifyReadData(int chunkInNAND,__u8 *data)
 102 {
 103         if(data)
 104         {
 105                 *data ^= yaffs_ReadFailCorruption(chunkInNAND);
 106         }
 107 }
 108
 109
 110
 111
 112
 113 static void  CheckInit(yaffs_Device *dev)
 114 {
 115         static int initialised = 0;
 116
 117         int length;
 118
 119
 120         if(!initialised)
 121         {
 122                 memset(ffChunk,0xFF,528);
 123
 124                 h = open("yaffs-em-file" , O_RDWR | O_CREAT, S_IREAD | S_IWRITE);
 125                 if(h < 0)
 126                 {
 127                         perror("Fatal error opening yaffs emulation file");
 128                         exit(1);
 129                 }
 130                 initialised = 1;
 131
 132                 length = lseek(h,0,SEEK_END);
 133                 if(length !=  FILE_SIZE_IN_BYTES)
 134                 {
 135                         // Create file contents
 136                         int i;
 137
 138                         printf("Creating emulation file...\n");
 139                         for(i = 0; i < FILE_SIZE_IN_BLOCKS; i++)
 140                         {
 141                                 yaffs_FEEraseBlockInNAND(dev,i);
 142
 143                                 if(IsAMarkedBadBlock(i))
 144                                 {
 145                                         yaffs_Spare spare;
 146                                         memset(&spare,0xff,sizeof(spare));
 147                                         spare.blockStatus = 1;
 148
 149                                         yaffs_FEWriteChunkToNAND(dev, i * 32,NULL,&spare);
 150                                 }
 151                         }
 152                 }
 153                 eraseDisplayEnabled = 1;
 154         }
 155 }
 156
 157 int yaffs_FEWriteChunkToNAND(yaffs_Device *dev,int chunkInNAND,const __u8 *data, yaffs_Spare *spare)
 158 {
 159         __u8 localData[512];
 160
 161         int pos;
 162
 163         pos = chunkInNAND * 528;
 164
 165         CheckInit(dev);
 166
 167
 168         if(data)
 169         {
 170                 memcpy(localData,data,512);
 171                 yaffs_ModifyWriteData(chunkInNAND,localData);
 172                 lseek(h,pos,SEEK_SET);
 173                 write(h,localData,512);
 174         }
 175
 176         pos += 512;
 177
 178         if(spare)
 179         {
 180                 lseek(h,pos,SEEK_SET);
 181                 write(h,spare,16);
 182         }
 183
 184         return YAFFS_OK;
 185 }
 186
 187
 188 int yaffs_FEReadChunkFromNAND(yaffs_Device *dev,int chunkInNAND, __u8 *data, yaffs_Spare *spare)
 189 {
 190         int pos;
 191
 192         pos = chunkInNAND * 528;
 193
 194
 195         CheckInit(dev);
 196
 197         if(data)
 198         {
 199                 lseek(h,pos,SEEK_SET);
 200                 read(h,data,512);
 201                 yaffs_ModifyReadData(chunkInNAND,data);
 202         }
 203
 204         pos += 512;
 205
 206         if(spare)
 207         {
 208                 lseek(h,pos,SEEK_SET);
 209                 read(h,spare,16);
 210         }
 211
 212         return YAFFS_OK;
 213 }
 214
 215
 216 int yaffs_FEEraseBlockInNAND(yaffs_Device *dev,int blockInNAND)
 217 {
 218         int i;
 219
 220         CheckInit(dev);
 221
 222         if(eraseDisplayEnabled)
 223         {
 224                 printf("Erasing block %d\n",blockInNAND);
 225         }
 226
 227         lseek(h,blockInNAND * BLOCK_SIZE,SEEK_SET);
 228         for(i = 0; i < 32; i++)
 229         {
 230                 write(h,ffChunk,528);
 231         }
 232
 233         switch(blockInNAND)
 234         {
 235                 case 10:
 236                 case 15: return YAFFS_FAIL;
 237
 238         }
 239         return YAFFS_OK;
 240 }
 241
 242 int yaffs_FEInitialiseNAND(yaffs_Device *dev)
 243 {
 244         return YAFFS_OK;
 245 }