LXR linux/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
  47static const char * const trx_types[] = { "trx", NULL };
  48
  49struct trx_header {
  50        uint32_t magic;
  51        uint32_t length;
  52        uint32_t crc32;
  53        uint16_t flags;
  54        uint16_t version;
  55        uint32_t offset[3];
  56} __packed;
  57
  58static void bcm47xxpart_add_part(struct mtd_partition *part, const char *name,
  59                                 u64 offset, uint32_t mask_flags)
  60{
  61        part->name = name;
  62        part->offset = offset;
  63        part->mask_flags = mask_flags;
  64}
  65
  66/**
  67 * bcm47xxpart_bootpartition - gets index of TRX partition used by bootloader
  68 *
  69 * Some devices may have more than one TRX partition. In such case one of them
  70 * is the main one and another a failsafe one. Bootloader may fallback to the
  71 * failsafe firmware if it detects corruption of the main image.
  72 *
  73 * This function provides info about currently used TRX partition. It's the one
  74 * containing kernel started by the bootloader.
  75 */
  76static int bcm47xxpart_bootpartition(void)
  77{
  78        char buf[4];
  79        int bootpartition;
  80
  81        /* Check CFE environment variable */
  82        if (bcm47xx_nvram_getenv("bootpartition", buf, sizeof(buf)) > 0) {
  83                if (!kstrtoint(buf, 0, &bootpartition))
  84                        return bootpartition;
  85        }
  86
  87        return 0;
  88}
  89
  90static int bcm47xxpart_parse(struct mtd_info *master,
  91                             const struct mtd_partition **pparts,
  92                             struct mtd_part_parser_data *data)
  93{
  94        struct mtd_partition *parts;
  95        uint8_t i, curr_part = 0;
  96        uint32_t *buf;
  97        size_t bytes_read;
  98        uint32_t offset;
  99        uint32_t blocksize = master->erasesize;
 100        int trx_parts[2]; /* Array with indexes of TRX partitions */
 101        int trx_num = 0; /* Number of found TRX partitions */
 102        int possible_nvram_sizes[] = { 0x8000, 0xF000, 0x10000, };
 103        int err;
 104
 105        /*
 106         * Some really old flashes (like AT45DB*) had smaller erasesize-s, but
 107         * partitions were aligned to at least 0x1000 anyway.
 108         */
 109        if (blocksize < 0x1000)
 110                blocksize = 0x1000;
 111
 112        /* Alloc */
 113        parts = kcalloc(BCM47XXPART_MAX_PARTS, sizeof(struct mtd_partition),
 114                        GFP_KERNEL);
 115        if (!parts)
 116                return -ENOMEM;
 117
 118        buf = kzalloc(BCM47XXPART_BYTES_TO_READ, GFP_KERNEL);
 119        if (!buf) {
 120                kfree(parts);
 121                return -ENOMEM;
 122        }
 123
 124        /* Parse block by block looking for magics */
 125        for (offset = 0; offset <= master->size - blocksize;
 126             offset += blocksize) {
 127                /* Nothing more in higher memory on BCM47XX (MIPS) */
 128                if (IS_ENABLED(CONFIG_BCM47XX) && offset >= 0x2000000)
 129                        break;
 130
 131                if (curr_part >= BCM47XXPART_MAX_PARTS) {
 132                        pr_warn("Reached maximum number of partitions, scanning stopped!\n");
 133                        break;
 134                }
 135
 136                /* Read beginning of the block */
 137                err = mtd_read(master, offset, BCM47XXPART_BYTES_TO_READ,
 138                               &bytes_read, (uint8_t *)buf);
 139                if (err && !mtd_is_bitflip(err)) {
 140                        pr_err("mtd_read error while parsing (offset: 0x%X): %d\n",
 141                               offset, err);
 142                        continue;
 143                }
 144
 145                /* Magic or small NVRAM at 0x400 */
 146                if ((buf[0x4e0 / 4] == CFE_MAGIC && buf[0x4e4 / 4] == CFE_MAGIC) ||
 147                    (buf[0x400 / 4] == NVRAM_HEADER)) {
 148                        bcm47xxpart_add_part(&parts[curr_part++], "boot",
 149                                             offset, MTD_WRITEABLE);
 150                        continue;
 151                }
 152
 153                /*
 154                 * board_data starts with board_id which differs across boards,
 155                 * but we can use 'MPFR' (hopefully) magic at 0x100
 156                 */
 157                if (buf[0x100 / 4] == BOARD_DATA_MAGIC) {
 158                        bcm47xxpart_add_part(&parts[curr_part++], "board_data",
 159                                             offset, MTD_WRITEABLE);
 160                        continue;
 161                }
 162
 163                /* Found on Huawei E970 */
 164                if (buf[0x000 / 4] == FACTORY_MAGIC) {
 165                        bcm47xxpart_add_part(&parts[curr_part++], "factory",
 166                                             offset, MTD_WRITEABLE);
 167                        continue;
 168                }
 169
 170                /* POT(TOP) */
 171                if (buf[0x000 / 4] == POT_MAGIC1 &&
 172                    (buf[0x004 / 4] & 0xFFFF) == POT_MAGIC2) {
 173                        bcm47xxpart_add_part(&parts[curr_part++], "POT", offset,
 174                                             MTD_WRITEABLE);
 175                        continue;
 176                }
 177
 178                /* ML */
 179                if (buf[0x010 / 4] == ML_MAGIC1 &&
 180                    buf[0x014 / 4] == ML_MAGIC2) {
 181                        bcm47xxpart_add_part(&parts[curr_part++], "ML", offset,
 182                                             MTD_WRITEABLE);
 183                        continue;
 184                }
 185
 186                /* TRX */
 187                if (buf[0x000 / 4] == TRX_MAGIC) {
 188                        struct trx_header *trx;
 189                        uint32_t last_subpart;
 190                        uint32_t trx_size;
 191
 192                        if (trx_num >= ARRAY_SIZE(trx_parts))
 193                                pr_warn("No enough space to store another TRX found at 0x%X\n",
 194                                        offset);
 195                        else
 196                                trx_parts[trx_num++] = curr_part;
 197                        bcm47xxpart_add_part(&parts[curr_part++], "firmware",
 198                                             offset, 0);
 199
 200                        /*
 201                         * Try to find TRX size. The "length" field isn't fully
 202                         * reliable as it could be decreased to make CRC32 cover
 203                         * only part of TRX data. It's commonly used as checksum
 204                         * can't cover e.g. ever-changing rootfs partition.
 205                         * Use offsets as helpers for assuming min TRX size.
 206                         */
 207                        trx = (struct trx_header *)buf;
 208                        last_subpart = max3(trx->offset[0], trx->offset[1],
 209                                            trx->offset[2]);
 210                        trx_size = max(trx->length, last_subpart + blocksize);
 211
 212                        /*
 213                         * Skip the TRX data. Decrease offset by block size as
 214                         * the next loop iteration will increase it.
 215                         */
 216                        offset += roundup(trx_size, blocksize) - blocksize;
 217                        continue;
 218                }
 219
 220                /* Squashfs on devices not using TRX */
 221                if (le32_to_cpu(buf[0x000 / 4]) == SQUASHFS_MAGIC ||
 222                    buf[0x000 / 4] == SHSQ_MAGIC) {
 223                        bcm47xxpart_add_part(&parts[curr_part++], "rootfs",
 224                                             offset, 0);
 225                        continue;
 226                }
 227
 228                /*
 229                 * New (ARM?) devices may have NVRAM in some middle block. Last
 230                 * block will be checked later, so skip it.
 231                 */
 232                if (offset != master->size - blocksize &&
 233                    buf[0x000 / 4] == NVRAM_HEADER) {
 234                        bcm47xxpart_add_part(&parts[curr_part++], "nvram",
 235                                             offset, 0);
 236                        continue;
 237                }
 238
 239                /* Read middle of the block */
 240                err = mtd_read(master, offset + 0x8000, 0x4, &bytes_read,
 241                               (uint8_t *)buf);
 242                if (err && !mtd_is_bitflip(err)) {
 243                        pr_err("mtd_read error while parsing (offset: 0x%X): %d\n",
 244                               offset, err);
 245                        continue;
 246                }
 247
 248                /* Some devices (ex. WNDR3700v3) don't have a standard 'MPFR' */
 249                if (buf[0x000 / 4] == BOARD_DATA_MAGIC2) {
 250                        bcm47xxpart_add_part(&parts[curr_part++], "board_data",
 251                                             offset, MTD_WRITEABLE);
 252                        continue;
 253                }
 254        }
 255
 256        /* Look for NVRAM at the end of the last block. */
 257        for (i = 0; i < ARRAY_SIZE(possible_nvram_sizes); i++) {
 258                if (curr_part >= BCM47XXPART_MAX_PARTS) {
 259                        pr_warn("Reached maximum number of partitions, scanning stopped!\n");
 260                        break;
 261                }
 262
 263                offset = master->size - possible_nvram_sizes[i];
 264                err = mtd_read(master, offset, 0x4, &bytes_read,
 265                               (uint8_t *)buf);
 266                if (err && !mtd_is_bitflip(err)) {
 267                        pr_err("mtd_read error while reading (offset 0x%X): %d\n",
 268                               offset, err);
 269                        continue;
 270                }
 271
 272                /* Standard NVRAM */
 273                if (buf[0] == NVRAM_HEADER) {
 274                        bcm47xxpart_add_part(&parts[curr_part++], "nvram",
 275                                             master->size - blocksize, 0);
 276                        break;
 277                }
 278        }
 279
 280        kfree(buf);
 281
 282        /*
 283         * Assume that partitions end at the beginning of the one they are
 284         * followed by.
 285         */
 286        for (i = 0; i < curr_part; i++) {
 287                u64 next_part_offset = (i < curr_part - 1) ?
 288                                       parts[i + 1].offset : master->size;
 289
 290                parts[i].size = next_part_offset - parts[i].offset;
 291        }
 292
 293        /* If there was TRX parse it now */
 294        for (i = 0; i < trx_num; i++) {
 295                struct mtd_partition *trx = &parts[trx_parts[i]];
 296
 297                if (i == bcm47xxpart_bootpartition())
 298                        trx->types = trx_types;
 299                else
 300                        trx->name = "failsafe";
 301        }
 302
 303        *pparts = parts;
 304        return curr_part;
 305};
 306
 307static const struct of_device_id bcm47xxpart_of_match_table[] = {
 308        { .compatible = "brcm,bcm947xx-cfe-partitions" },
 309        {},
 310};
 311MODULE_DEVICE_TABLE(of, bcm47xxpart_of_match_table);
 312
 313static struct mtd_part_parser bcm47xxpart_mtd_parser = {
 314        .parse_fn = bcm47xxpart_parse,
 315        .name = "bcm47xxpart",
 316        .of_match_table = bcm47xxpart_of_match_table,
 317};
 318module_mtd_part_parser(bcm47xxpart_mtd_parser);
 319
 320MODULE_LICENSE("GPL");
 321MODULE_DESCRIPTION("MTD partitioning for BCM47XX flash memories");
 322