drivers/mtd/bcm47xxpart.c

   1 /*
   2  * BCM47XX MTD partitioning
   3  *
   4  * Copyright © 2012 Rafał Miłecki <zajec5@gmail.com>
   5  *
   6  * This program is free software; you can redistribute it and/or modify
   7  * it under the terms of the GNU General Public License version 2 as
   8  * published by the Free Software Foundation.
   9  *
  10  */
  11
  12 #include <linux/module.h>
  13 #include <linux/kernel.h>
  14 #include <linux/slab.h>
  15 #include <linux/mtd/mtd.h>
  16 #include <linux/mtd/partitions.h>
  17
  18 /* 10 parts were found on sflash on Netgear WNDR4500 */
  19 #define BCM47XXPART_MAX_PARTS           12
  20
  21 /*
  22  * Amount of bytes we read when analyzing each block of flash memory.
  23  * Set it big enough to allow detecting partition and reading important data.
  24  */
  25 #define BCM47XXPART_BYTES_TO_READ       0x4e8
  26
  27 /* Magics */
  28 #define BOARD_DATA_MAGIC                0x5246504D      /* MPFR */
  29 #define BOARD_DATA_MAGIC2               0xBD0D0BBD
  30 #define CFE_MAGIC                       0x43464531      /* 1EFC */
  31 #define FACTORY_MAGIC                   0x59544346      /* FCTY */
  32 #define NVRAM_HEADER                    0x48534C46      /* FLSH */
  33 #define POT_MAGIC1                      0x54544f50      /* POTT */
  34 #define POT_MAGIC2                      0x504f          /* OP */
  35 #define ML_MAGIC1                       0x39685a42
  36 #define ML_MAGIC2                       0x26594131
  37 #define TRX_MAGIC                       0x30524448
  38 #define SQSH_MAGIC                      0x71736873      /* shsq */
  39
  40 struct trx_header {
  41         uint32_t magic;
  42         uint32_t length;
  43         uint32_t crc32;
  44         uint16_t flags;
  45         uint16_t version;
  46         uint32_t offset[3];
  47 } __packed;
  48
  49 static void bcm47xxpart_add_part(struct mtd_partition *part, char *name,
  50                                  u64 offset, uint32_t mask_flags)
  51 {
  52         part->name = name;
  53         part->offset = offset;
  54         part->mask_flags = mask_flags;
  55 }
  56
  57 static int bcm47xxpart_parse(struct mtd_info *master,
  58                              struct mtd_partition **pparts,
  59                              struct mtd_part_parser_data *data)
  60 {
  61         struct mtd_partition *parts;
  62         uint8_t i, curr_part = 0;
  63         uint32_t *buf;
  64         size_t bytes_read;
  65         uint32_t offset;
  66         uint32_t blocksize = master->erasesize;
  67         struct trx_header *trx;
  68         int trx_part = -1;
  69         int last_trx_part = -1;
  70         int possible_nvram_sizes[] = { 0x8000, 0xF000, 0x10000, };
  71
  72         if (blocksize <= 0x10000)
  73                 blocksize = 0x10000;
  74
  75         /* Alloc */
  76         parts = kzalloc(sizeof(struct mtd_partition) * BCM47XXPART_MAX_PARTS,
  77                         GFP_KERNEL);
  78         if (!parts)
  79                 return -ENOMEM;
  80
  81         buf = kzalloc(BCM47XXPART_BYTES_TO_READ, GFP_KERNEL);
  82         if (!buf) {
  83                 kfree(parts);
  84                 return -ENOMEM;
  85         }
  86
  87         /* Parse block by block looking for magics */
  88         for (offset = 0; offset <= master->size - blocksize;
  89              offset += blocksize) {
  90                 /* Nothing more in higher memory */
  91                 if (offset >= 0x2000000)
  92                         break;
  93
  94                 if (curr_part >= BCM47XXPART_MAX_PARTS) {
  95                         pr_warn("Reached maximum number of partitions, scanning stopped!\n");
  96                         break;
  97                 }
  98
  99                 /* Read beginning of the block */
 100                 if (mtd_read(master, offset, BCM47XXPART_BYTES_TO_READ,
 101                              &bytes_read, (uint8_t *)buf) < 0) {
 102                         pr_err("mtd_read error while parsing (offset: 0x%X)!\n",
 103                                offset);
 104                         continue;
 105                 }
 106
 107                 /* Magic or small NVRAM at 0x400 */
 108                 if ((buf[0x4e0 / 4] == CFE_MAGIC && buf[0x4e4 / 4] == CFE_MAGIC) ||
 109                     (buf[0x400 / 4] == NVRAM_HEADER)) {
 110                         bcm47xxpart_add_part(&parts[curr_part++], "boot",
 111                                              offset, MTD_WRITEABLE);
 112                         continue;
 113                 }
 114
 115                 /*
 116                  * board_data starts with board_id which differs across boards,
 117                  * but we can use 'MPFR' (hopefully) magic at 0x100
 118                  */
 119                 if (buf[0x100 / 4] == BOARD_DATA_MAGIC) {
 120                         bcm47xxpart_add_part(&parts[curr_part++], "board_data",
 121                                              offset, MTD_WRITEABLE);
 122                         continue;
 123                 }
 124
 125                 /* Found on Huawei E970 */
 126                 if (buf[0x000 / 4] == FACTORY_MAGIC) {
 127                         bcm47xxpart_add_part(&parts[curr_part++], "factory",
 128                                              offset, MTD_WRITEABLE);
 129                         continue;
 130                 }
 131
 132                 /* POT(TOP) */
 133                 if (buf[0x000 / 4] == POT_MAGIC1 &&
 134                     (buf[0x004 / 4] & 0xFFFF) == POT_MAGIC2) {
 135                         bcm47xxpart_add_part(&parts[curr_part++], "POT", offset,
 136                                              MTD_WRITEABLE);
 137                         continue;
 138                 }
 139
 140                 /* ML */
 141                 if (buf[0x010 / 4] == ML_MAGIC1 &&
 142                     buf[0x014 / 4] == ML_MAGIC2) {
 143                         bcm47xxpart_add_part(&parts[curr_part++], "ML", offset,
 144                                              MTD_WRITEABLE);
 145                         continue;
 146                 }
 147
 148                 /* TRX */
 149                 if (buf[0x000 / 4] == TRX_MAGIC) {
 150                         if (BCM47XXPART_MAX_PARTS - curr_part < 4) {
 151                                 pr_warn("Not enough partitions left to register trx, scanning stopped!\n");
 152                                 break;
 153                         }
 154
 155                         trx = (struct trx_header *)buf;
 156
 157                         trx_part = curr_part;
 158                         bcm47xxpart_add_part(&parts[curr_part++], "firmware",
 159                                              offset, 0);
 160
 161                         i = 0;
 162                         /* We have LZMA loader if offset[2] points to sth */
 163                         if (trx->offset[2]) {
 164                                 bcm47xxpart_add_part(&parts[curr_part++],
 165                                                      "loader",
 166                                                      offset + trx->offset[i],
 167                                                      0);
 168                                 i++;
 169                         }
 170
 171                         bcm47xxpart_add_part(&parts[curr_part++], "linux",
 172                                              offset + trx->offset[i], 0);
 173                         i++;
 174
 175                         /*
 176                          * Pure rootfs size is known and can be calculated as:
 177                          * trx->length - trx->offset[i]. We don't fill it as
 178                          * we want to have jffs2 (overlay) in the same mtd.
 179                          */
 180                         bcm47xxpart_add_part(&parts[curr_part++], "rootfs",
 181                                              offset + trx->offset[i], 0);
 182                         i++;
 183
 184                         last_trx_part = curr_part - 1;
 185
 186                         /*
 187                          * We have whole TRX scanned, skip to the next part. Use
 188                          * roundown (not roundup), as the loop will increase
 189                          * offset in next step.
 190                          */
 191                         offset = rounddown(offset + trx->length, blocksize);
 192                         continue;
 193                 }
 194
 195                 /* Squashfs on devices not using TRX */
 196                 if (buf[0x000 / 4] == SQSH_MAGIC) {
 197                         bcm47xxpart_add_part(&parts[curr_part++], "rootfs",
 198                                              offset, 0);
 199                         continue;
 200                 }
 201
 202                 /* Read middle of the block */
 203                 if (mtd_read(master, offset + 0x8000, 0x4,
 204                              &bytes_read, (uint8_t *)buf) < 0) {
 205                         pr_err("mtd_read error while parsing (offset: 0x%X)!\n",
 206                                offset);
 207                         continue;
 208                 }
 209
 210                 /* Some devices (ex. WNDR3700v3) don't have a standard 'MPFR' */
 211                 if (buf[0x000 / 4] == BOARD_DATA_MAGIC2) {
 212                         bcm47xxpart_add_part(&parts[curr_part++], "board_data",
 213                                              offset, MTD_WRITEABLE);
 214                         continue;
 215                 }
 216         }
 217
 218         /* Look for NVRAM at the end of the last block. */
 219         for (i = 0; i < ARRAY_SIZE(possible_nvram_sizes); i++) {
 220                 if (curr_part >= BCM47XXPART_MAX_PARTS) {
 221                         pr_warn("Reached maximum number of partitions, scanning stopped!\n");
 222                         break;
 223                 }
 224
 225                 offset = master->size - possible_nvram_sizes[i];
 226                 if (mtd_read(master, offset, 0x4, &bytes_read,
 227                              (uint8_t *)buf) < 0) {
 228                         pr_err("mtd_read error while reading at offset 0x%X!\n",
 229                                offset);
 230                         continue;
 231                 }
 232
 233                 /* Standard NVRAM */
 234                 if (buf[0] == NVRAM_HEADER) {
 235                         bcm47xxpart_add_part(&parts[curr_part++], "nvram",
 236                                              master->size - blocksize, 0);
 237                         break;
 238                 }
 239         }
 240
 241         kfree(buf);
 242
 243         /*
 244          * Assume that partitions end at the beginning of the one they are
 245          * followed by.
 246          */
 247         for (i = 0; i < curr_part; i++) {
 248                 u64 next_part_offset = (i < curr_part - 1) ?
 249                                        parts[i + 1].offset : master->size;
 250
 251                 parts[i].size = next_part_offset - parts[i].offset;
 252                 if (i == last_trx_part && trx_part >= 0)
 253                         parts[trx_part].size = next_part_offset -
 254                                                parts[trx_part].offset;
 255         }
 256
 257         *pparts = parts;
 258         return curr_part;
 259 };
 260
 261 static struct mtd_part_parser bcm47xxpart_mtd_parser = {
 262         .owner = THIS_MODULE,
 263         .parse_fn = bcm47xxpart_parse,
 264         .name = "bcm47xxpart",
 265 };
 266
 267 static int __init bcm47xxpart_init(void)
 268 {
 269         register_mtd_parser(&bcm47xxpart_mtd_parser);
 270         return 0;
 271 }
 272
 273 static void __exit bcm47xxpart_exit(void)
 274 {
 275         deregister_mtd_parser(&bcm47xxpart_mtd_parser);
 276 }
 277
 278 module_init(bcm47xxpart_init);
 279 module_exit(bcm47xxpart_exit);
 280
 281 MODULE_LICENSE("GPL");
 282 MODULE_DESCRIPTION("MTD partitioning for BCM47XX flash memories");