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/bcm47xx_nvram.h>
  13 #include <linux/module.h>
  14 #include <linux/kernel.h>
  15 #include <linux/slab.h>
  16 #include <linux/mtd/mtd.h>
  17 #include <linux/mtd/partitions.h>
  18
  19 #include <uapi/linux/magic.h>
  20
  21 /*
  22  * NAND flash on Netgear R6250 was verified to contain 15 partitions.
  23  * This will result in allocating too big array for some old devices, but the
  24  * memory will be freed soon anyway (see mtd_device_parse_register).
  25  */
  26 #define BCM47XXPART_MAX_PARTS           20
  27
  28 /*
  29  * Amount of bytes we read when analyzing each block of flash memory.
  30  * Set it big enough to allow detecting partition and reading important data.
  31  */
  32 #define BCM47XXPART_BYTES_TO_READ       0x4e8
  33
  34 /* Magics */
  35 #define BOARD_DATA_MAGIC                0x5246504D      /* MPFR */
  36 #define BOARD_DATA_MAGIC2               0xBD0D0BBD
  37 #define CFE_MAGIC                       0x43464531      /* 1EFC */
  38 #define FACTORY_MAGIC                   0x59544346      /* FCTY */
  39 #define NVRAM_HEADER                    0x48534C46      /* FLSH */
  40 #define POT_MAGIC1                      0x54544f50      /* POTT */
  41 #define POT_MAGIC2                      0x504f          /* OP */
  42 #define ML_MAGIC1                       0x39685a42
  43 #define ML_MAGIC2                       0x26594131
  44 #define TRX_MAGIC                       0x30524448
  45 #define SHSQ_MAGIC                      0x71736873      /* shsq (weird ZTE H218N endianness) */
  46 #define UBI_EC_MAGIC                    0x23494255      /* UBI# */
  47
  48 struct trx_header {
  49         uint32_t magic;
  50         uint32_t length;
  51         uint32_t crc32;
  52         uint16_t flags;
  53         uint16_t version;
  54         uint32_t offset[3];
  55 } __packed;
  56
  57 static void bcm47xxpart_add_part(struct mtd_partition *part, const char *name,
  58                                  u64 offset, uint32_t mask_flags)
  59 {
  60         part->name = name;
  61         part->offset = offset;
  62         part->mask_flags = mask_flags;
  63 }
  64
  65 static const char *bcm47xxpart_trx_data_part_name(struct mtd_info *master,
  66                                                   size_t offset)
  67 {
  68         uint32_t buf;
  69         size_t bytes_read;
  70         int err;
  71
  72         err  = mtd_read(master, offset, sizeof(buf), &bytes_read,
  73                         (uint8_t *)&buf);
  74         if (err && !mtd_is_bitflip(err)) {
  75                 pr_err("mtd_read error while parsing (offset: 0x%X): %d\n",
  76                         offset, err);
  77                 goto out_default;
  78         }
  79
  80         if (buf == UBI_EC_MAGIC)
  81                 return "ubi";
  82
  83 out_default:
  84         return "rootfs";
  85 }
  86
  87 static int bcm47xxpart_parse_trx(struct mtd_info *master,
  88                                  struct mtd_partition *trx,
  89                                  struct mtd_partition *parts,
  90                                  size_t parts_len)
  91 {
  92         struct trx_header header;
  93         size_t bytes_read;
  94         int curr_part = 0;
  95         int i, err;
  96
  97         if (parts_len < 3) {
  98                 pr_warn("No enough space to add TRX partitions!\n");
  99                 return -ENOMEM;
 100         }
 101
 102         err = mtd_read(master, trx->offset, sizeof(header), &bytes_read,
 103                        (uint8_t *)&header);
 104         if (err && !mtd_is_bitflip(err)) {
 105                 pr_err("mtd_read error while reading TRX header: %d\n", err);
 106                 return err;
 107         }
 108
 109         i = 0;
 110
 111         /* We have LZMA loader if offset[2] points to sth */
 112         if (header.offset[2]) {
 113                 bcm47xxpart_add_part(&parts[curr_part++], "loader",
 114                                      trx->offset + header.offset[i], 0);
 115                 i++;
 116         }
 117
 118         if (header.offset[i]) {
 119                 bcm47xxpart_add_part(&parts[curr_part++], "linux",
 120                                      trx->offset + header.offset[i], 0);
 121                 i++;
 122         }
 123
 124         if (header.offset[i]) {
 125                 size_t offset = trx->offset + header.offset[i];
 126                 const char *name = bcm47xxpart_trx_data_part_name(master,
 127                                                                   offset);
 128
 129                 bcm47xxpart_add_part(&parts[curr_part++], name, offset, 0);
 130                 i++;
 131         }
 132
 133         /*
 134          * Assume that every partition ends at the beginning of the one it is
 135          * followed by.
 136          */
 137         for (i = 0; i < curr_part; i++) {
 138                 u64 next_part_offset = (i < curr_part - 1) ?
 139                                         parts[i + 1].offset :
 140                                         trx->offset + trx->size;
 141
 142                 parts[i].size = next_part_offset - parts[i].offset;
 143         }
 144
 145         return curr_part;
 146 }
 147
 148 /**
 149  * bcm47xxpart_bootpartition - gets index of TRX partition used by bootloader
 150  *
 151  * Some devices may have more than one TRX partition. In such case one of them
 152  * is the main one and another a failsafe one. Bootloader may fallback to the
 153  * failsafe firmware if it detects corruption of the main image.
 154  *
 155  * This function provides info about currently used TRX partition. It's the one
 156  * containing kernel started by the bootloader.
 157  */
 158 static int bcm47xxpart_bootpartition(void)
 159 {
 160         char buf[4];
 161         int bootpartition;
 162
 163         /* Check CFE environment variable */
 164         if (bcm47xx_nvram_getenv("bootpartition", buf, sizeof(buf)) > 0) {
 165                 if (!kstrtoint(buf, 0, &bootpartition))
 166                         return bootpartition;
 167         }
 168
 169         return 0;
 170 }
 171
 172 static int bcm47xxpart_parse(struct mtd_info *master,
 173                              const struct mtd_partition **pparts,
 174                              struct mtd_part_parser_data *data)
 175 {
 176         struct mtd_partition *parts;
 177         uint8_t i, curr_part = 0;
 178         uint32_t *buf;
 179         size_t bytes_read;
 180         uint32_t offset;
 181         uint32_t blocksize = master->erasesize;
 182         int trx_parts[2]; /* Array with indexes of TRX partitions */
 183         int trx_num = 0; /* Number of found TRX partitions */
 184         int possible_nvram_sizes[] = { 0x8000, 0xF000, 0x10000, };
 185         int err;
 186
 187         /*
 188          * Some really old flashes (like AT45DB*) had smaller erasesize-s, but
 189          * partitions were aligned to at least 0x1000 anyway.
 190          */
 191         if (blocksize < 0x1000)
 192                 blocksize = 0x1000;
 193
 194         /* Alloc */
 195         parts = kzalloc(sizeof(struct mtd_partition) * BCM47XXPART_MAX_PARTS,
 196                         GFP_KERNEL);
 197         if (!parts)
 198                 return -ENOMEM;
 199
 200         buf = kzalloc(BCM47XXPART_BYTES_TO_READ, GFP_KERNEL);
 201         if (!buf) {
 202                 kfree(parts);
 203                 return -ENOMEM;
 204         }
 205
 206         /* Parse block by block looking for magics */
 207         for (offset = 0; offset <= master->size - blocksize;
 208              offset += blocksize) {
 209                 /* Nothing more in higher memory on BCM47XX (MIPS) */
 210                 if (IS_ENABLED(CONFIG_BCM47XX) && offset >= 0x2000000)
 211                         break;
 212
 213                 if (curr_part >= BCM47XXPART_MAX_PARTS) {
 214                         pr_warn("Reached maximum number of partitions, scanning stopped!\n");
 215                         break;
 216                 }
 217
 218                 /* Read beginning of the block */
 219                 err = mtd_read(master, offset, BCM47XXPART_BYTES_TO_READ,
 220                                &bytes_read, (uint8_t *)buf);
 221                 if (err && !mtd_is_bitflip(err)) {
 222                         pr_err("mtd_read error while parsing (offset: 0x%X): %d\n",
 223                                offset, err);
 224                         continue;
 225                 }
 226
 227                 /* Magic or small NVRAM at 0x400 */
 228                 if ((buf[0x4e0 / 4] == CFE_MAGIC && buf[0x4e4 / 4] == CFE_MAGIC) ||
 229                     (buf[0x400 / 4] == NVRAM_HEADER)) {
 230                         bcm47xxpart_add_part(&parts[curr_part++], "boot",
 231                                              offset, MTD_WRITEABLE);
 232                         continue;
 233                 }
 234
 235                 /*
 236                  * board_data starts with board_id which differs across boards,
 237                  * but we can use 'MPFR' (hopefully) magic at 0x100
 238                  */
 239                 if (buf[0x100 / 4] == BOARD_DATA_MAGIC) {
 240                         bcm47xxpart_add_part(&parts[curr_part++], "board_data",
 241                                              offset, MTD_WRITEABLE);
 242                         continue;
 243                 }
 244
 245                 /* Found on Huawei E970 */
 246                 if (buf[0x000 / 4] == FACTORY_MAGIC) {
 247                         bcm47xxpart_add_part(&parts[curr_part++], "factory",
 248                                              offset, MTD_WRITEABLE);
 249                         continue;
 250                 }
 251
 252                 /* POT(TOP) */
 253                 if (buf[0x000 / 4] == POT_MAGIC1 &&
 254                     (buf[0x004 / 4] & 0xFFFF) == POT_MAGIC2) {
 255                         bcm47xxpart_add_part(&parts[curr_part++], "POT", offset,
 256                                              MTD_WRITEABLE);
 257                         continue;
 258                 }
 259
 260                 /* ML */
 261                 if (buf[0x010 / 4] == ML_MAGIC1 &&
 262                     buf[0x014 / 4] == ML_MAGIC2) {
 263                         bcm47xxpart_add_part(&parts[curr_part++], "ML", offset,
 264                                              MTD_WRITEABLE);
 265                         continue;
 266                 }
 267
 268                 /* TRX */
 269                 if (buf[0x000 / 4] == TRX_MAGIC) {
 270                         struct trx_header *trx;
 271
 272                         if (trx_num >= ARRAY_SIZE(trx_parts))
 273                                 pr_warn("No enough space to store another TRX found at 0x%X\n",
 274                                         offset);
 275                         else
 276                                 trx_parts[trx_num++] = curr_part;
 277                         bcm47xxpart_add_part(&parts[curr_part++], "firmware",
 278                                              offset, 0);
 279
 280                         /* Jump to the end of TRX */
 281                         trx = (struct trx_header *)buf;
 282                         offset = roundup(offset + trx->length, blocksize);
 283                         /* Next loop iteration will increase the offset */
 284                         offset -= blocksize;
 285                         continue;
 286                 }
 287
 288                 /* Squashfs on devices not using TRX */
 289                 if (le32_to_cpu(buf[0x000 / 4]) == SQUASHFS_MAGIC ||
 290                     buf[0x000 / 4] == SHSQ_MAGIC) {
 291                         bcm47xxpart_add_part(&parts[curr_part++], "rootfs",
 292                                              offset, 0);
 293                         continue;
 294                 }
 295
 296                 /*
 297                  * New (ARM?) devices may have NVRAM in some middle block. Last
 298                  * block will be checked later, so skip it.
 299                  */
 300                 if (offset != master->size - blocksize &&
 301                     buf[0x000 / 4] == NVRAM_HEADER) {
 302                         bcm47xxpart_add_part(&parts[curr_part++], "nvram",
 303                                              offset, 0);
 304                         continue;
 305                 }
 306
 307                 /* Read middle of the block */
 308                 err = mtd_read(master, offset + 0x8000, 0x4, &bytes_read,
 309                                (uint8_t *)buf);
 310                 if (err && !mtd_is_bitflip(err)) {
 311                         pr_err("mtd_read error while parsing (offset: 0x%X): %d\n",
 312                                offset, err);
 313                         continue;
 314                 }
 315
 316                 /* Some devices (ex. WNDR3700v3) don't have a standard 'MPFR' */
 317                 if (buf[0x000 / 4] == BOARD_DATA_MAGIC2) {
 318                         bcm47xxpart_add_part(&parts[curr_part++], "board_data",
 319                                              offset, MTD_WRITEABLE);
 320                         continue;
 321                 }
 322         }
 323
 324         /* Look for NVRAM at the end of the last block. */
 325         for (i = 0; i < ARRAY_SIZE(possible_nvram_sizes); i++) {
 326                 if (curr_part >= BCM47XXPART_MAX_PARTS) {
 327                         pr_warn("Reached maximum number of partitions, scanning stopped!\n");
 328                         break;
 329                 }
 330
 331                 offset = master->size - possible_nvram_sizes[i];
 332                 err = mtd_read(master, offset, 0x4, &bytes_read,
 333                                (uint8_t *)buf);
 334                 if (err && !mtd_is_bitflip(err)) {
 335                         pr_err("mtd_read error while reading (offset 0x%X): %d\n",
 336                                offset, err);
 337                         continue;
 338                 }
 339
 340                 /* Standard NVRAM */
 341                 if (buf[0] == NVRAM_HEADER) {
 342                         bcm47xxpart_add_part(&parts[curr_part++], "nvram",
 343                                              master->size - blocksize, 0);
 344                         break;
 345                 }
 346         }
 347
 348         kfree(buf);
 349
 350         /*
 351          * Assume that partitions end at the beginning of the one they are
 352          * followed by.
 353          */
 354         for (i = 0; i < curr_part; i++) {
 355                 u64 next_part_offset = (i < curr_part - 1) ?
 356                                        parts[i + 1].offset : master->size;
 357
 358                 parts[i].size = next_part_offset - parts[i].offset;
 359         }
 360
 361         /* If there was TRX parse it now */
 362         for (i = 0; i < trx_num; i++) {
 363                 struct mtd_partition *trx = &parts[trx_parts[i]];
 364
 365                 if (i == bcm47xxpart_bootpartition()) {
 366                         int num_parts;
 367
 368                         num_parts = bcm47xxpart_parse_trx(master, trx,
 369                                                           parts + curr_part,
 370                                                           BCM47XXPART_MAX_PARTS - curr_part);
 371                         if (num_parts > 0)
 372                                 curr_part += num_parts;
 373                 } else {
 374                         trx->name = "failsafe";
 375                 }
 376         }
 377
 378         *pparts = parts;
 379         return curr_part;
 380 };
 381
 382 static struct mtd_part_parser bcm47xxpart_mtd_parser = {
 383         .parse_fn = bcm47xxpart_parse,
 384         .name = "bcm47xxpart",
 385 };
 386 module_mtd_part_parser(bcm47xxpart_mtd_parser);
 387
 388 MODULE_LICENSE("GPL");
 389 MODULE_DESCRIPTION("MTD partitioning for BCM47XX flash memories");