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
  47 static const char * const trx_types[] = { "trx", NULL };
  48
  49 struct 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
  58 static 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  */
  76 static 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
  90 static 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
 307 static const struct of_device_id bcm47xxpart_of_match_table[] = {
 308         { .compatible = "brcm,bcm947xx-cfe-partitions" },
 309         {},
 310 };
 311 MODULE_DEVICE_TABLE(of, bcm47xxpart_of_match_table);
 312
 313 static struct mtd_part_parser bcm47xxpart_mtd_parser = {
 314         .parse_fn = bcm47xxpart_parse,
 315         .name = "bcm47xxpart",
 316         .of_match_table = bcm47xxpart_of_match_table,
 317 };
 318 module_mtd_part_parser(bcm47xxpart_mtd_parser);
 319
 320 MODULE_LICENSE("GPL");
 321 MODULE_DESCRIPTION("MTD partitioning for BCM47XX flash memories");