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 #include <uapi/linux/magic.h>
  19
  20 /*
  21  * NAND flash on Netgear R6250 was verified to contain 15 partitions.
  22  * This will result in allocating too big array for some old devices, but the
  23  * memory will be freed soon anyway (see mtd_device_parse_register).
  24  */
  25 #define BCM47XXPART_MAX_PARTS           20
  26
  27 /*
  28  * Amount of bytes we read when analyzing each block of flash memory.
  29  * Set it big enough to allow detecting partition and reading important data.
  30  */
  31 #define BCM47XXPART_BYTES_TO_READ       0x4e8
  32
  33 /* Magics */
  34 #define BOARD_DATA_MAGIC                0x5246504D      /* MPFR */
  35 #define BOARD_DATA_MAGIC2               0xBD0D0BBD
  36 #define CFE_MAGIC                       0x43464531      /* 1EFC */
  37 #define FACTORY_MAGIC                   0x59544346      /* FCTY */
  38 #define NVRAM_HEADER                    0x48534C46      /* FLSH */
  39 #define POT_MAGIC1                      0x54544f50      /* POTT */
  40 #define POT_MAGIC2                      0x504f          /* OP */
  41 #define ML_MAGIC1                       0x39685a42
  42 #define ML_MAGIC2                       0x26594131
  43 #define TRX_MAGIC                       0x30524448
  44 #define SHSQ_MAGIC                      0x71736873      /* shsq (weird ZTE H218N endianness) */
  45 #define UBI_EC_MAGIC                    0x23494255      /* UBI# */
  46
  47 struct trx_header {
  48         uint32_t magic;
  49         uint32_t length;
  50         uint32_t crc32;
  51         uint16_t flags;
  52         uint16_t version;
  53         uint32_t offset[3];
  54 } __packed;
  55
  56 static void bcm47xxpart_add_part(struct mtd_partition *part, const char *name,
  57                                  u64 offset, uint32_t mask_flags)
  58 {
  59         part->name = name;
  60         part->offset = offset;
  61         part->mask_flags = mask_flags;
  62 }
  63
  64 static const char *bcm47xxpart_trx_data_part_name(struct mtd_info *master,
  65                                                   size_t offset)
  66 {
  67         uint32_t buf;
  68         size_t bytes_read;
  69
  70         if (mtd_read(master, offset, sizeof(buf), &bytes_read,
  71                      (uint8_t *)&buf) < 0) {
  72                 pr_err("mtd_read error while parsing (offset: 0x%X)!\n",
  73                         offset);
  74                 goto out_default;
  75         }
  76
  77         if (buf == UBI_EC_MAGIC)
  78                 return "ubi";
  79
  80 out_default:
  81         return "rootfs";
  82 }
  83
  84 static int bcm47xxpart_parse(struct mtd_info *master,
  85                              struct mtd_partition **pparts,
  86                              struct mtd_part_parser_data *data)
  87 {
  88         struct mtd_partition *parts;
  89         uint8_t i, curr_part = 0;
  90         uint32_t *buf;
  91         size_t bytes_read;
  92         uint32_t offset;
  93         uint32_t blocksize = master->erasesize;
  94         struct trx_header *trx;
  95         int trx_part = -1;
  96         int last_trx_part = -1;
  97         int possible_nvram_sizes[] = { 0x8000, 0xF000, 0x10000, };
  98
  99         /*
 100          * Some really old flashes (like AT45DB*) had smaller erasesize-s, but
 101          * partitions were aligned to at least 0x1000 anyway.
 102          */
 103         if (blocksize < 0x1000)
 104                 blocksize = 0x1000;
 105
 106         /* Alloc */
 107         parts = kzalloc(sizeof(struct mtd_partition) * BCM47XXPART_MAX_PARTS,
 108                         GFP_KERNEL);
 109         if (!parts)
 110                 return -ENOMEM;
 111
 112         buf = kzalloc(BCM47XXPART_BYTES_TO_READ, GFP_KERNEL);
 113         if (!buf) {
 114                 kfree(parts);
 115                 return -ENOMEM;
 116         }
 117
 118         /* Parse block by block looking for magics */
 119         for (offset = 0; offset <= master->size - blocksize;
 120              offset += blocksize) {
 121                 /* Nothing more in higher memory */
 122                 if (offset >= 0x2000000)
 123                         break;
 124
 125                 if (curr_part >= BCM47XXPART_MAX_PARTS) {
 126                         pr_warn("Reached maximum number of partitions, scanning stopped!\n");
 127                         break;
 128                 }
 129
 130                 /* Read beginning of the block */
 131                 if (mtd_read(master, offset, BCM47XXPART_BYTES_TO_READ,
 132                              &bytes_read, (uint8_t *)buf) < 0) {
 133                         pr_err("mtd_read error while parsing (offset: 0x%X)!\n",
 134                                offset);
 135                         continue;
 136                 }
 137
 138                 /* Magic or small NVRAM at 0x400 */
 139                 if ((buf[0x4e0 / 4] == CFE_MAGIC && buf[0x4e4 / 4] == CFE_MAGIC) ||
 140                     (buf[0x400 / 4] == NVRAM_HEADER)) {
 141                         bcm47xxpart_add_part(&parts[curr_part++], "boot",
 142                                              offset, MTD_WRITEABLE);
 143                         continue;
 144                 }
 145
 146                 /*
 147                  * board_data starts with board_id which differs across boards,
 148                  * but we can use 'MPFR' (hopefully) magic at 0x100
 149                  */
 150                 if (buf[0x100 / 4] == BOARD_DATA_MAGIC) {
 151                         bcm47xxpart_add_part(&parts[curr_part++], "board_data",
 152                                              offset, MTD_WRITEABLE);
 153                         continue;
 154                 }
 155
 156                 /* Found on Huawei E970 */
 157                 if (buf[0x000 / 4] == FACTORY_MAGIC) {
 158                         bcm47xxpart_add_part(&parts[curr_part++], "factory",
 159                                              offset, MTD_WRITEABLE);
 160                         continue;
 161                 }
 162
 163                 /* POT(TOP) */
 164                 if (buf[0x000 / 4] == POT_MAGIC1 &&
 165                     (buf[0x004 / 4] & 0xFFFF) == POT_MAGIC2) {
 166                         bcm47xxpart_add_part(&parts[curr_part++], "POT", offset,
 167                                              MTD_WRITEABLE);
 168                         continue;
 169                 }
 170
 171                 /* ML */
 172                 if (buf[0x010 / 4] == ML_MAGIC1 &&
 173                     buf[0x014 / 4] == ML_MAGIC2) {
 174                         bcm47xxpart_add_part(&parts[curr_part++], "ML", offset,
 175                                              MTD_WRITEABLE);
 176                         continue;
 177                 }
 178
 179                 /* TRX */
 180                 if (buf[0x000 / 4] == TRX_MAGIC) {
 181                         if (BCM47XXPART_MAX_PARTS - curr_part < 4) {
 182                                 pr_warn("Not enough partitions left to register trx, scanning stopped!\n");
 183                                 break;
 184                         }
 185
 186                         trx = (struct trx_header *)buf;
 187
 188                         trx_part = curr_part;
 189                         bcm47xxpart_add_part(&parts[curr_part++], "firmware",
 190                                              offset, 0);
 191
 192                         i = 0;
 193                         /* We have LZMA loader if offset[2] points to sth */
 194                         if (trx->offset[2]) {
 195                                 bcm47xxpart_add_part(&parts[curr_part++],
 196                                                      "loader",
 197                                                      offset + trx->offset[i],
 198                                                      0);
 199                                 i++;
 200                         }
 201
 202                         if (trx->offset[i]) {
 203                                 bcm47xxpart_add_part(&parts[curr_part++],
 204                                                      "linux",
 205                                                      offset + trx->offset[i],
 206                                                      0);
 207                                 i++;
 208                         }
 209
 210                         /*
 211                          * Pure rootfs size is known and can be calculated as:
 212                          * trx->length - trx->offset[i]. We don't fill it as
 213                          * we want to have jffs2 (overlay) in the same mtd.
 214                          */
 215                         if (trx->offset[i]) {
 216                                 const char *name;
 217
 218                                 name = bcm47xxpart_trx_data_part_name(master, offset + trx->offset[i]);
 219                                 bcm47xxpart_add_part(&parts[curr_part++],
 220                                                      name,
 221                                                      offset + trx->offset[i],
 222                                                      0);
 223                                 i++;
 224                         }
 225
 226                         last_trx_part = curr_part - 1;
 227
 228                         /*
 229                          * We have whole TRX scanned, skip to the next part. Use
 230                          * roundown (not roundup), as the loop will increase
 231                          * offset in next step.
 232                          */
 233                         offset = rounddown(offset + trx->length, blocksize);
 234                         continue;
 235                 }
 236
 237                 /* Squashfs on devices not using TRX */
 238                 if (le32_to_cpu(buf[0x000 / 4]) == SQUASHFS_MAGIC ||
 239                     buf[0x000 / 4] == SHSQ_MAGIC) {
 240                         bcm47xxpart_add_part(&parts[curr_part++], "rootfs",
 241                                              offset, 0);
 242                         continue;
 243                 }
 244
 245                 /*
 246                  * New (ARM?) devices may have NVRAM in some middle block. Last
 247                  * block will be checked later, so skip it.
 248                  */
 249                 if (offset != master->size - blocksize &&
 250                     buf[0x000 / 4] == NVRAM_HEADER) {
 251                         bcm47xxpart_add_part(&parts[curr_part++], "nvram",
 252                                              offset, 0);
 253                         continue;
 254                 }
 255
 256                 /* Read middle of the block */
 257                 if (mtd_read(master, offset + 0x8000, 0x4,
 258                              &bytes_read, (uint8_t *)buf) < 0) {
 259                         pr_err("mtd_read error while parsing (offset: 0x%X)!\n",
 260                                offset);
 261                         continue;
 262                 }
 263
 264                 /* Some devices (ex. WNDR3700v3) don't have a standard 'MPFR' */
 265                 if (buf[0x000 / 4] == BOARD_DATA_MAGIC2) {
 266                         bcm47xxpart_add_part(&parts[curr_part++], "board_data",
 267                                              offset, MTD_WRITEABLE);
 268                         continue;
 269                 }
 270         }
 271
 272         /* Look for NVRAM at the end of the last block. */
 273         for (i = 0; i < ARRAY_SIZE(possible_nvram_sizes); i++) {
 274                 if (curr_part >= BCM47XXPART_MAX_PARTS) {
 275                         pr_warn("Reached maximum number of partitions, scanning stopped!\n");
 276                         break;
 277                 }
 278
 279                 offset = master->size - possible_nvram_sizes[i];
 280                 if (mtd_read(master, offset, 0x4, &bytes_read,
 281                              (uint8_t *)buf) < 0) {
 282                         pr_err("mtd_read error while reading at offset 0x%X!\n",
 283                                offset);
 284                         continue;
 285                 }
 286
 287                 /* Standard NVRAM */
 288                 if (buf[0] == NVRAM_HEADER) {
 289                         bcm47xxpart_add_part(&parts[curr_part++], "nvram",
 290                                              master->size - blocksize, 0);
 291                         break;
 292                 }
 293         }
 294
 295         kfree(buf);
 296
 297         /*
 298          * Assume that partitions end at the beginning of the one they are
 299          * followed by.
 300          */
 301         for (i = 0; i < curr_part; i++) {
 302                 u64 next_part_offset = (i < curr_part - 1) ?
 303                                        parts[i + 1].offset : master->size;
 304
 305                 parts[i].size = next_part_offset - parts[i].offset;
 306                 if (i == last_trx_part && trx_part >= 0)
 307                         parts[trx_part].size = next_part_offset -
 308                                                parts[trx_part].offset;
 309         }
 310
 311         *pparts = parts;
 312         return curr_part;
 313 };
 314
 315 static struct mtd_part_parser bcm47xxpart_mtd_parser = {
 316         .owner = THIS_MODULE,
 317         .parse_fn = bcm47xxpart_parse,
 318         .name = "bcm47xxpart",
 319 };
 320
 321 static int __init bcm47xxpart_init(void)
 322 {
 323         register_mtd_parser(&bcm47xxpart_mtd_parser);
 324         return 0;
 325 }
 326
 327 static void __exit bcm47xxpart_exit(void)
 328 {
 329         deregister_mtd_parser(&bcm47xxpart_mtd_parser);
 330 }
 331
 332 module_init(bcm47xxpart_init);
 333 module_exit(bcm47xxpart_exit);
 334
 335 MODULE_LICENSE("GPL");
 336 MODULE_DESCRIPTION("MTD partitioning for BCM47XX flash memories");