drivers/mtd/parsers/bcm47xxpart.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * BCM47XX MTD partitioning
   4  *
   5  * Copyright © 2012 Rafał Miłecki <zajec5@gmail.com>
   6  */
   7
   8 #include <linux/bcm47xx_nvram.h>
   9 #include <linux/module.h>
  10 #include <linux/kernel.h>
  11 #include <linux/slab.h>
  12 #include <linux/mtd/mtd.h>
  13 #include <linux/mtd/partitions.h>
  14
  15 #include <uapi/linux/magic.h>
  16
  17 /*
  18  * NAND flash on Netgear R6250 was verified to contain 15 partitions.
  19  * This will result in allocating too big array for some old devices, but the
  20  * memory will be freed soon anyway (see mtd_device_parse_register).
  21  */
  22 #define BCM47XXPART_MAX_PARTS           20
  23
  24 /*
  25  * Amount of bytes we read when analyzing each block of flash memory.
  26  * Set it big enough to allow detecting partition and reading important data.
  27  */
  28 #define BCM47XXPART_BYTES_TO_READ       0x4e8
  29
  30 /* Magics */
  31 #define BOARD_DATA_MAGIC                0x5246504D      /* MPFR */
  32 #define BOARD_DATA_MAGIC2               0xBD0D0BBD
  33 #define CFE_MAGIC                       0x43464531      /* 1EFC */
  34 #define FACTORY_MAGIC                   0x59544346      /* FCTY */
  35 #define NVRAM_HEADER                    0x48534C46      /* FLSH */
  36 #define POT_MAGIC1                      0x54544f50      /* POTT */
  37 #define POT_MAGIC2                      0x504f          /* OP */
  38 #define ML_MAGIC1                       0x39685a42
  39 #define ML_MAGIC2                       0x26594131
  40 #define TRX_MAGIC                       0x30524448
  41 #define SHSQ_MAGIC                      0x71736873      /* shsq (weird ZTE H218N endianness) */
  42
  43 static const char * const trx_types[] = { "trx", NULL };
  44
  45 struct trx_header {
  46         uint32_t magic;
  47         uint32_t length;
  48         uint32_t crc32;
  49         uint16_t flags;
  50         uint16_t version;
  51         uint32_t offset[3];
  52 } __packed;
  53
  54 static void bcm47xxpart_add_part(struct mtd_partition *part, const char *name,
  55                                  u64 offset, uint32_t mask_flags)
  56 {
  57         part->name = name;
  58         part->offset = offset;
  59         part->mask_flags = mask_flags;
  60 }
  61
  62 /**
  63  * bcm47xxpart_bootpartition - gets index of TRX partition used by bootloader
  64  *
  65  * Some devices may have more than one TRX partition. In such case one of them
  66  * is the main one and another a failsafe one. Bootloader may fallback to the
  67  * failsafe firmware if it detects corruption of the main image.
  68  *
  69  * This function provides info about currently used TRX partition. It's the one
  70  * containing kernel started by the bootloader.
  71  */
  72 static int bcm47xxpart_bootpartition(void)
  73 {
  74         char buf[4];
  75         int bootpartition;
  76
  77         /* Check CFE environment variable */
  78         if (bcm47xx_nvram_getenv("bootpartition", buf, sizeof(buf)) > 0) {
  79                 if (!kstrtoint(buf, 0, &bootpartition))
  80                         return bootpartition;
  81         }
  82
  83         return 0;
  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         int trx_parts[2]; /* Array with indexes of TRX partitions */
  97         int trx_num = 0; /* Number of found TRX partitions */
  98         int possible_nvram_sizes[] = { 0x8000, 0xF000, 0x10000, };
  99         int err;
 100
 101         /*
 102          * Some really old flashes (like AT45DB*) had smaller erasesize-s, but
 103          * partitions were aligned to at least 0x1000 anyway.
 104          */
 105         if (blocksize < 0x1000)
 106                 blocksize = 0x1000;
 107
 108         /* Alloc */
 109         parts = kcalloc(BCM47XXPART_MAX_PARTS, sizeof(struct mtd_partition),
 110                         GFP_KERNEL);
 111         if (!parts)
 112                 return -ENOMEM;
 113
 114         buf = kzalloc(BCM47XXPART_BYTES_TO_READ, GFP_KERNEL);
 115         if (!buf) {
 116                 kfree(parts);
 117                 return -ENOMEM;
 118         }
 119
 120         /* Parse block by block looking for magics */
 121         for (offset = 0; offset <= master->size - blocksize;
 122              offset += blocksize) {
 123                 /* Nothing more in higher memory on BCM47XX (MIPS) */
 124                 if (IS_ENABLED(CONFIG_BCM47XX) && offset >= 0x2000000)
 125                         break;
 126
 127                 if (curr_part >= BCM47XXPART_MAX_PARTS) {
 128                         pr_warn("Reached maximum number of partitions, scanning stopped!\n");
 129                         break;
 130                 }
 131
 132                 /* Read beginning of the block */
 133                 err = mtd_read(master, offset, BCM47XXPART_BYTES_TO_READ,
 134                                &bytes_read, (uint8_t *)buf);
 135                 if (err && !mtd_is_bitflip(err)) {
 136                         pr_err("mtd_read error while parsing (offset: 0x%X): %d\n",
 137                                offset, err);
 138                         continue;
 139                 }
 140
 141                 /* Magic or small NVRAM at 0x400 */
 142                 if ((buf[0x4e0 / 4] == CFE_MAGIC && buf[0x4e4 / 4] == CFE_MAGIC) ||
 143                     (buf[0x400 / 4] == NVRAM_HEADER)) {
 144                         bcm47xxpart_add_part(&parts[curr_part++], "boot",
 145                                              offset, MTD_WRITEABLE);
 146                         continue;
 147                 }
 148
 149                 /*
 150                  * board_data starts with board_id which differs across boards,
 151                  * but we can use 'MPFR' (hopefully) magic at 0x100
 152                  */
 153                 if (buf[0x100 / 4] == BOARD_DATA_MAGIC) {
 154                         bcm47xxpart_add_part(&parts[curr_part++], "board_data",
 155                                              offset, MTD_WRITEABLE);
 156                         continue;
 157                 }
 158
 159                 /* Found on Huawei E970 */
 160                 if (buf[0x000 / 4] == FACTORY_MAGIC) {
 161                         bcm47xxpart_add_part(&parts[curr_part++], "factory",
 162                                              offset, MTD_WRITEABLE);
 163                         continue;
 164                 }
 165
 166                 /* POT(TOP) */
 167                 if (buf[0x000 / 4] == POT_MAGIC1 &&
 168                     (buf[0x004 / 4] & 0xFFFF) == POT_MAGIC2) {
 169                         bcm47xxpart_add_part(&parts[curr_part++], "POT", offset,
 170                                              MTD_WRITEABLE);
 171                         continue;
 172                 }
 173
 174                 /* ML */
 175                 if (buf[0x010 / 4] == ML_MAGIC1 &&
 176                     buf[0x014 / 4] == ML_MAGIC2) {
 177                         bcm47xxpart_add_part(&parts[curr_part++], "ML", offset,
 178                                              MTD_WRITEABLE);
 179                         continue;
 180                 }
 181
 182                 /* TRX */
 183                 if (buf[0x000 / 4] == TRX_MAGIC) {
 184                         struct trx_header *trx;
 185                         uint32_t last_subpart;
 186                         uint32_t trx_size;
 187
 188                         if (trx_num >= ARRAY_SIZE(trx_parts))
 189                                 pr_warn("No enough space to store another TRX found at 0x%X\n",
 190                                         offset);
 191                         else
 192                                 trx_parts[trx_num++] = curr_part;
 193                         bcm47xxpart_add_part(&parts[curr_part++], "firmware",
 194                                              offset, 0);
 195
 196                         /*
 197                          * Try to find TRX size. The "length" field isn't fully
 198                          * reliable as it could be decreased to make CRC32 cover
 199                          * only part of TRX data. It's commonly used as checksum
 200                          * can't cover e.g. ever-changing rootfs partition.
 201                          * Use offsets as helpers for assuming min TRX size.
 202                          */
 203                         trx = (struct trx_header *)buf;
 204                         last_subpart = max3(trx->offset[0], trx->offset[1],
 205                                             trx->offset[2]);
 206                         trx_size = max(trx->length, last_subpart + blocksize);
 207
 208                         /*
 209                          * Skip the TRX data. Decrease offset by block size as
 210                          * the next loop iteration will increase it.
 211                          */
 212                         offset += roundup(trx_size, blocksize) - blocksize;
 213                         continue;
 214                 }
 215
 216                 /* Squashfs on devices not using TRX */
 217                 if (le32_to_cpu(buf[0x000 / 4]) == SQUASHFS_MAGIC ||
 218                     buf[0x000 / 4] == SHSQ_MAGIC) {
 219                         bcm47xxpart_add_part(&parts[curr_part++], "rootfs",
 220                                              offset, 0);
 221                         continue;
 222                 }
 223
 224                 /*
 225                  * New (ARM?) devices may have NVRAM in some middle block. Last
 226                  * block will be checked later, so skip it.
 227                  */
 228                 if (offset != master->size - blocksize &&
 229                     buf[0x000 / 4] == NVRAM_HEADER) {
 230                         bcm47xxpart_add_part(&parts[curr_part++], "nvram",
 231                                              offset, 0);
 232                         continue;
 233                 }
 234
 235                 /* Read middle of the block */
 236                 err = mtd_read(master, offset + 0x8000, 0x4, &bytes_read,
 237                                (uint8_t *)buf);
 238                 if (err && !mtd_is_bitflip(err)) {
 239                         pr_err("mtd_read error while parsing (offset: 0x%X): %d\n",
 240                                offset, err);
 241                         continue;
 242                 }
 243
 244                 /* Some devices (ex. WNDR3700v3) don't have a standard 'MPFR' */
 245                 if (buf[0x000 / 4] == BOARD_DATA_MAGIC2) {
 246                         bcm47xxpart_add_part(&parts[curr_part++], "board_data",
 247                                              offset, MTD_WRITEABLE);
 248                         continue;
 249                 }
 250         }
 251
 252         /* Look for NVRAM at the end of the last block. */
 253         for (i = 0; i < ARRAY_SIZE(possible_nvram_sizes); i++) {
 254                 if (curr_part >= BCM47XXPART_MAX_PARTS) {
 255                         pr_warn("Reached maximum number of partitions, scanning stopped!\n");
 256                         break;
 257                 }
 258
 259                 offset = master->size - possible_nvram_sizes[i];
 260                 err = mtd_read(master, offset, 0x4, &bytes_read,
 261                                (uint8_t *)buf);
 262                 if (err && !mtd_is_bitflip(err)) {
 263                         pr_err("mtd_read error while reading (offset 0x%X): %d\n",
 264                                offset, err);
 265                         continue;
 266                 }
 267
 268                 /* Standard NVRAM */
 269                 if (buf[0] == NVRAM_HEADER) {
 270                         bcm47xxpart_add_part(&parts[curr_part++], "nvram",
 271                                              master->size - blocksize, 0);
 272                         break;
 273                 }
 274         }
 275
 276         kfree(buf);
 277
 278         /*
 279          * Assume that partitions end at the beginning of the one they are
 280          * followed by.
 281          */
 282         for (i = 0; i < curr_part; i++) {
 283                 u64 next_part_offset = (i < curr_part - 1) ?
 284                                        parts[i + 1].offset : master->size;
 285
 286                 parts[i].size = next_part_offset - parts[i].offset;
 287         }
 288
 289         /* If there was TRX parse it now */
 290         for (i = 0; i < trx_num; i++) {
 291                 struct mtd_partition *trx = &parts[trx_parts[i]];
 292
 293                 if (i == bcm47xxpart_bootpartition())
 294                         trx->types = trx_types;
 295                 else
 296                         trx->name = "failsafe";
 297         }
 298
 299         *pparts = parts;
 300         return curr_part;
 301 };
 302
 303 static const struct of_device_id bcm47xxpart_of_match_table[] = {
 304         { .compatible = "brcm,bcm947xx-cfe-partitions" },
 305         {},
 306 };
 307 MODULE_DEVICE_TABLE(of, bcm47xxpart_of_match_table);
 308
 309 static struct mtd_part_parser bcm47xxpart_mtd_parser = {
 310         .parse_fn = bcm47xxpart_parse,
 311         .name = "bcm47xxpart",
 312         .of_match_table = bcm47xxpart_of_match_table,
 313 };
 314 module_mtd_part_parser(bcm47xxpart_mtd_parser);
 315
 316 MODULE_LICENSE("GPL");
 317 MODULE_DESCRIPTION("MTD partitioning for BCM47XX flash memories");