linux/drivers/mtd/parsers/bcm47xxpart.c
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   1// SPDX-License-Identifier: GPL-2.0-only
   2/*
   3 * BCM47XX MTD partitioning
   4 *
   5 * Copyright \xC2\xA9 2012 Rafa\xC5\x82 Mi\xC5\x82ecki <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
  43static const char * const trx_types[] = { "trx", NULL };
  44
  45struct 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
  54static 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 */
  72static 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
  86static 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
 303static const struct of_device_id bcm47xxpart_of_match_table[] = {
 304        { .compatible = "brcm,bcm947xx-cfe-partitions" },
 305        {},
 306};
 307MODULE_DEVICE_TABLE(of, bcm47xxpart_of_match_table);
 308
 309static struct mtd_part_parser bcm47xxpart_mtd_parser = {
 310        .parse_fn = bcm47xxpart_parse,
 311        .name = "bcm47xxpart",
 312        .of_match_table = bcm47xxpart_of_match_table,
 313};
 314module_mtd_part_parser(bcm47xxpart_mtd_parser);
 315
 316MODULE_LICENSE("GPL");
 317MODULE_DESCRIPTION("MTD partitioning for BCM47XX flash memories");
 318