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         int err;
  70
  71         err  = mtd_read(master, offset, sizeof(buf), &bytes_read,
  72                         (uint8_t *)&buf);
  73         if (err && !mtd_is_bitflip(err)) {
  74                 pr_err("mtd_read error while parsing (offset: 0x%X): %d\n",
  75                         offset, err);
  76                 goto out_default;
  77         }
  78
  79         if (buf == UBI_EC_MAGIC)
  80                 return "ubi";
  81
  82 out_default:
  83         return "rootfs";
  84 }
  85
  86 static int bcm47xxpart_parse(struct mtd_info *master,
  87                              const struct mtd_partition **pparts,
  88                              struct mtd_part_parser_data *data)
  89 {
  90         struct mtd_partition *parts;
  91         uint8_t i, curr_part = 0;
  92         uint32_t *buf;
  93         size_t bytes_read;
  94         uint32_t offset;
  95         uint32_t blocksize = master->erasesize;
  96         struct trx_header *trx;
  97         int trx_part = -1;
  98         int last_trx_part = -1;
  99         int possible_nvram_sizes[] = { 0x8000, 0xF000, 0x10000, };
 100         int err;
 101
 102         /*
 103          * Some really old flashes (like AT45DB*) had smaller erasesize-s, but
 104          * partitions were aligned to at least 0x1000 anyway.
 105          */
 106         if (blocksize < 0x1000)
 107                 blocksize = 0x1000;
 108
 109         /* Alloc */
 110         parts = kzalloc(sizeof(struct mtd_partition) * BCM47XXPART_MAX_PARTS,
 111                         GFP_KERNEL);
 112         if (!parts)
 113                 return -ENOMEM;
 114
 115         buf = kzalloc(BCM47XXPART_BYTES_TO_READ, GFP_KERNEL);
 116         if (!buf) {
 117                 kfree(parts);
 118                 return -ENOMEM;
 119         }
 120
 121         /* Parse block by block looking for magics */
 122         for (offset = 0; offset <= master->size - blocksize;
 123              offset += blocksize) {
 124                 /* Nothing more in higher memory on BCM47XX (MIPS) */
 125                 if (config_enabled(CONFIG_BCM47XX) && offset >= 0x2000000)
 126                         break;
 127
 128                 if (curr_part >= BCM47XXPART_MAX_PARTS) {
 129                         pr_warn("Reached maximum number of partitions, scanning stopped!\n");
 130                         break;
 131                 }
 132
 133                 /* Read beginning of the block */
 134                 err = mtd_read(master, offset, BCM47XXPART_BYTES_TO_READ,
 135                                &bytes_read, (uint8_t *)buf);
 136                 if (err && !mtd_is_bitflip(err)) {
 137                         pr_err("mtd_read error while parsing (offset: 0x%X): %d\n",
 138                                offset, err);
 139                         continue;
 140                 }
 141
 142                 /* Magic or small NVRAM at 0x400 */
 143                 if ((buf[0x4e0 / 4] == CFE_MAGIC && buf[0x4e4 / 4] == CFE_MAGIC) ||
 144                     (buf[0x400 / 4] == NVRAM_HEADER)) {
 145                         bcm47xxpart_add_part(&parts[curr_part++], "boot",
 146                                              offset, MTD_WRITEABLE);
 147                         continue;
 148                 }
 149
 150                 /*
 151                  * board_data starts with board_id which differs across boards,
 152                  * but we can use 'MPFR' (hopefully) magic at 0x100
 153                  */
 154                 if (buf[0x100 / 4] == BOARD_DATA_MAGIC) {
 155                         bcm47xxpart_add_part(&parts[curr_part++], "board_data",
 156                                              offset, MTD_WRITEABLE);
 157                         continue;
 158                 }
 159
 160                 /* Found on Huawei E970 */
 161                 if (buf[0x000 / 4] == FACTORY_MAGIC) {
 162                         bcm47xxpart_add_part(&parts[curr_part++], "factory",
 163                                              offset, MTD_WRITEABLE);
 164                         continue;
 165                 }
 166
 167                 /* POT(TOP) */
 168                 if (buf[0x000 / 4] == POT_MAGIC1 &&
 169                     (buf[0x004 / 4] & 0xFFFF) == POT_MAGIC2) {
 170                         bcm47xxpart_add_part(&parts[curr_part++], "POT", offset,
 171                                              MTD_WRITEABLE);
 172                         continue;
 173                 }
 174
 175                 /* ML */
 176                 if (buf[0x010 / 4] == ML_MAGIC1 &&
 177                     buf[0x014 / 4] == ML_MAGIC2) {
 178                         bcm47xxpart_add_part(&parts[curr_part++], "ML", offset,
 179                                              MTD_WRITEABLE);
 180                         continue;
 181                 }
 182
 183                 /* TRX */
 184                 if (buf[0x000 / 4] == TRX_MAGIC) {
 185                         if (BCM47XXPART_MAX_PARTS - curr_part < 4) {
 186                                 pr_warn("Not enough partitions left to register trx, scanning stopped!\n");
 187                                 break;
 188                         }
 189
 190                         trx = (struct trx_header *)buf;
 191
 192                         trx_part = curr_part;
 193                         bcm47xxpart_add_part(&parts[curr_part++], "firmware",
 194                                              offset, 0);
 195
 196                         i = 0;
 197                         /* We have LZMA loader if offset[2] points to sth */
 198                         if (trx->offset[2]) {
 199                                 bcm47xxpart_add_part(&parts[curr_part++],
 200                                                      "loader",
 201                                                      offset + trx->offset[i],
 202                                                      0);
 203                                 i++;
 204                         }
 205
 206                         if (trx->offset[i]) {
 207                                 bcm47xxpart_add_part(&parts[curr_part++],
 208                                                      "linux",
 209                                                      offset + trx->offset[i],
 210                                                      0);
 211                                 i++;
 212                         }
 213
 214                         /*
 215                          * Pure rootfs size is known and can be calculated as:
 216                          * trx->length - trx->offset[i]. We don't fill it as
 217                          * we want to have jffs2 (overlay) in the same mtd.
 218                          */
 219                         if (trx->offset[i]) {
 220                                 const char *name;
 221
 222                                 name = bcm47xxpart_trx_data_part_name(master, offset + trx->offset[i]);
 223                                 bcm47xxpart_add_part(&parts[curr_part++],
 224                                                      name,
 225                                                      offset + trx->offset[i],
 226                                                      0);
 227                                 i++;
 228                         }
 229
 230                         last_trx_part = curr_part - 1;
 231
 232                         /*
 233                          * We have whole TRX scanned, skip to the next part. Use
 234                          * roundown (not roundup), as the loop will increase
 235                          * offset in next step.
 236                          */
 237                         offset = rounddown(offset + trx->length, blocksize);
 238                         continue;
 239                 }
 240
 241                 /* Squashfs on devices not using TRX */
 242                 if (le32_to_cpu(buf[0x000 / 4]) == SQUASHFS_MAGIC ||
 243                     buf[0x000 / 4] == SHSQ_MAGIC) {
 244                         bcm47xxpart_add_part(&parts[curr_part++], "rootfs",
 245                                              offset, 0);
 246                         continue;
 247                 }
 248
 249                 /*
 250                  * New (ARM?) devices may have NVRAM in some middle block. Last
 251                  * block will be checked later, so skip it.
 252                  */
 253                 if (offset != master->size - blocksize &&
 254                     buf[0x000 / 4] == NVRAM_HEADER) {
 255                         bcm47xxpart_add_part(&parts[curr_part++], "nvram",
 256                                              offset, 0);
 257                         continue;
 258                 }
 259
 260                 /* Read middle of the block */
 261                 err = mtd_read(master, offset + 0x8000, 0x4, &bytes_read,
 262                                (uint8_t *)buf);
 263                 if (err && !mtd_is_bitflip(err)) {
 264                         pr_err("mtd_read error while parsing (offset: 0x%X): %d\n",
 265                                offset, err);
 266                         continue;
 267                 }
 268
 269                 /* Some devices (ex. WNDR3700v3) don't have a standard 'MPFR' */
 270                 if (buf[0x000 / 4] == BOARD_DATA_MAGIC2) {
 271                         bcm47xxpart_add_part(&parts[curr_part++], "board_data",
 272                                              offset, MTD_WRITEABLE);
 273                         continue;
 274                 }
 275         }
 276
 277         /* Look for NVRAM at the end of the last block. */
 278         for (i = 0; i < ARRAY_SIZE(possible_nvram_sizes); i++) {
 279                 if (curr_part >= BCM47XXPART_MAX_PARTS) {
 280                         pr_warn("Reached maximum number of partitions, scanning stopped!\n");
 281                         break;
 282                 }
 283
 284                 offset = master->size - possible_nvram_sizes[i];
 285                 err = mtd_read(master, offset, 0x4, &bytes_read,
 286                                (uint8_t *)buf);
 287                 if (err && !mtd_is_bitflip(err)) {
 288                         pr_err("mtd_read error while reading (offset 0x%X): %d\n",
 289                                offset, err);
 290                         continue;
 291                 }
 292
 293                 /* Standard NVRAM */
 294                 if (buf[0] == NVRAM_HEADER) {
 295                         bcm47xxpart_add_part(&parts[curr_part++], "nvram",
 296                                              master->size - blocksize, 0);
 297                         break;
 298                 }
 299         }
 300
 301         kfree(buf);
 302
 303         /*
 304          * Assume that partitions end at the beginning of the one they are
 305          * followed by.
 306          */
 307         for (i = 0; i < curr_part; i++) {
 308                 u64 next_part_offset = (i < curr_part - 1) ?
 309                                        parts[i + 1].offset : master->size;
 310
 311                 parts[i].size = next_part_offset - parts[i].offset;
 312                 if (i == last_trx_part && trx_part >= 0)
 313                         parts[trx_part].size = next_part_offset -
 314                                                parts[trx_part].offset;
 315         }
 316
 317         *pparts = parts;
 318         return curr_part;
 319 };
 320
 321 static struct mtd_part_parser bcm47xxpart_mtd_parser = {
 322         .parse_fn = bcm47xxpart_parse,
 323         .name = "bcm47xxpart",
 324 };
 325 module_mtd_part_parser(bcm47xxpart_mtd_parser);
 326
 327 MODULE_LICENSE("GPL");
 328 MODULE_DESCRIPTION("MTD partitioning for BCM47XX flash memories");