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 /*
  19  * NAND flash on Netgear R6250 was verified to contain 15 partitions.
  20  * This will result in allocating too big array for some old devices, but the
  21  * memory will be freed soon anyway (see mtd_device_parse_register).
  22  */
  23 #define BCM47XXPART_MAX_PARTS           20
  24
  25 /*
  26  * Amount of bytes we read when analyzing each block of flash memory.
  27  * Set it big enough to allow detecting partition and reading important data.
  28  */
  29 #define BCM47XXPART_BYTES_TO_READ       0x4e8
  30
  31 /* Magics */
  32 #define BOARD_DATA_MAGIC                0x5246504D      /* MPFR */
  33 #define BOARD_DATA_MAGIC2               0xBD0D0BBD
  34 #define CFE_MAGIC                       0x43464531      /* 1EFC */
  35 #define FACTORY_MAGIC                   0x59544346      /* FCTY */
  36 #define NVRAM_HEADER                    0x48534C46      /* FLSH */
  37 #define POT_MAGIC1                      0x54544f50      /* POTT */
  38 #define POT_MAGIC2                      0x504f          /* OP */
  39 #define ML_MAGIC1                       0x39685a42
  40 #define ML_MAGIC2                       0x26594131
  41 #define TRX_MAGIC                       0x30524448
  42 #define SQSH_MAGIC                      0x71736873      /* shsq */
  43
  44 struct trx_header {
  45         uint32_t magic;
  46         uint32_t length;
  47         uint32_t crc32;
  48         uint16_t flags;
  49         uint16_t version;
  50         uint32_t offset[3];
  51 } __packed;
  52
  53 static void bcm47xxpart_add_part(struct mtd_partition *part, char *name,
  54                                  u64 offset, uint32_t mask_flags)
  55 {
  56         part->name = name;
  57         part->offset = offset;
  58         part->mask_flags = mask_flags;
  59 }
  60
  61 static int bcm47xxpart_parse(struct mtd_info *master,
  62                              struct mtd_partition **pparts,
  63                              struct mtd_part_parser_data *data)
  64 {
  65         struct mtd_partition *parts;
  66         uint8_t i, curr_part = 0;
  67         uint32_t *buf;
  68         size_t bytes_read;
  69         uint32_t offset;
  70         uint32_t blocksize = master->erasesize;
  71         struct trx_header *trx;
  72         int trx_part = -1;
  73         int last_trx_part = -1;
  74         int possible_nvram_sizes[] = { 0x8000, 0xF000, 0x10000, };
  75
  76         if (blocksize <= 0x10000)
  77                 blocksize = 0x10000;
  78
  79         /* Alloc */
  80         parts = kzalloc(sizeof(struct mtd_partition) * BCM47XXPART_MAX_PARTS,
  81                         GFP_KERNEL);
  82         if (!parts)
  83                 return -ENOMEM;
  84
  85         buf = kzalloc(BCM47XXPART_BYTES_TO_READ, GFP_KERNEL);
  86         if (!buf) {
  87                 kfree(parts);
  88                 return -ENOMEM;
  89         }
  90
  91         /* Parse block by block looking for magics */
  92         for (offset = 0; offset <= master->size - blocksize;
  93              offset += blocksize) {
  94                 /* Nothing more in higher memory */
  95                 if (offset >= 0x2000000)
  96                         break;
  97
  98                 if (curr_part >= BCM47XXPART_MAX_PARTS) {
  99                         pr_warn("Reached maximum number of partitions, scanning stopped!\n");
 100                         break;
 101                 }
 102
 103                 /* Read beginning of the block */
 104                 if (mtd_read(master, offset, BCM47XXPART_BYTES_TO_READ,
 105                              &bytes_read, (uint8_t *)buf) < 0) {
 106                         pr_err("mtd_read error while parsing (offset: 0x%X)!\n",
 107                                offset);
 108                         continue;
 109                 }
 110
 111                 /* Magic or small NVRAM at 0x400 */
 112                 if ((buf[0x4e0 / 4] == CFE_MAGIC && buf[0x4e4 / 4] == CFE_MAGIC) ||
 113                     (buf[0x400 / 4] == NVRAM_HEADER)) {
 114                         bcm47xxpart_add_part(&parts[curr_part++], "boot",
 115                                              offset, MTD_WRITEABLE);
 116                         continue;
 117                 }
 118
 119                 /*
 120                  * board_data starts with board_id which differs across boards,
 121                  * but we can use 'MPFR' (hopefully) magic at 0x100
 122                  */
 123                 if (buf[0x100 / 4] == BOARD_DATA_MAGIC) {
 124                         bcm47xxpart_add_part(&parts[curr_part++], "board_data",
 125                                              offset, MTD_WRITEABLE);
 126                         continue;
 127                 }
 128
 129                 /* Found on Huawei E970 */
 130                 if (buf[0x000 / 4] == FACTORY_MAGIC) {
 131                         bcm47xxpart_add_part(&parts[curr_part++], "factory",
 132                                              offset, MTD_WRITEABLE);
 133                         continue;
 134                 }
 135
 136                 /* POT(TOP) */
 137                 if (buf[0x000 / 4] == POT_MAGIC1 &&
 138                     (buf[0x004 / 4] & 0xFFFF) == POT_MAGIC2) {
 139                         bcm47xxpart_add_part(&parts[curr_part++], "POT", offset,
 140                                              MTD_WRITEABLE);
 141                         continue;
 142                 }
 143
 144                 /* ML */
 145                 if (buf[0x010 / 4] == ML_MAGIC1 &&
 146                     buf[0x014 / 4] == ML_MAGIC2) {
 147                         bcm47xxpart_add_part(&parts[curr_part++], "ML", offset,
 148                                              MTD_WRITEABLE);
 149                         continue;
 150                 }
 151
 152                 /* TRX */
 153                 if (buf[0x000 / 4] == TRX_MAGIC) {
 154                         if (BCM47XXPART_MAX_PARTS - curr_part < 4) {
 155                                 pr_warn("Not enough partitions left to register trx, scanning stopped!\n");
 156                                 break;
 157                         }
 158
 159                         trx = (struct trx_header *)buf;
 160
 161                         trx_part = curr_part;
 162                         bcm47xxpart_add_part(&parts[curr_part++], "firmware",
 163                                              offset, 0);
 164
 165                         i = 0;
 166                         /* We have LZMA loader if offset[2] points to sth */
 167                         if (trx->offset[2]) {
 168                                 bcm47xxpart_add_part(&parts[curr_part++],
 169                                                      "loader",
 170                                                      offset + trx->offset[i],
 171                                                      0);
 172                                 i++;
 173                         }
 174
 175                         if (trx->offset[i]) {
 176                                 bcm47xxpart_add_part(&parts[curr_part++],
 177                                                      "linux",
 178                                                      offset + trx->offset[i],
 179                                                      0);
 180                                 i++;
 181                         }
 182
 183                         /*
 184                          * Pure rootfs size is known and can be calculated as:
 185                          * trx->length - trx->offset[i]. We don't fill it as
 186                          * we want to have jffs2 (overlay) in the same mtd.
 187                          */
 188                         if (trx->offset[i]) {
 189                                 bcm47xxpart_add_part(&parts[curr_part++],
 190                                                      "rootfs",
 191                                                      offset + trx->offset[i],
 192                                                      0);
 193                                 i++;
 194                         }
 195
 196                         last_trx_part = curr_part - 1;
 197
 198                         /*
 199                          * We have whole TRX scanned, skip to the next part. Use
 200                          * roundown (not roundup), as the loop will increase
 201                          * offset in next step.
 202                          */
 203                         offset = rounddown(offset + trx->length, blocksize);
 204                         continue;
 205                 }
 206
 207                 /* Squashfs on devices not using TRX */
 208                 if (buf[0x000 / 4] == SQSH_MAGIC) {
 209                         bcm47xxpart_add_part(&parts[curr_part++], "rootfs",
 210                                              offset, 0);
 211                         continue;
 212                 }
 213
 214                 /*
 215                  * New (ARM?) devices may have NVRAM in some middle block. Last
 216                  * block will be checked later, so skip it.
 217                  */
 218                 if (offset != master->size - blocksize &&
 219                     buf[0x000 / 4] == NVRAM_HEADER) {
 220                         bcm47xxpart_add_part(&parts[curr_part++], "nvram",
 221                                              offset, 0);
 222                         continue;
 223                 }
 224
 225                 /* Read middle of the block */
 226                 if (mtd_read(master, offset + 0x8000, 0x4,
 227                              &bytes_read, (uint8_t *)buf) < 0) {
 228                         pr_err("mtd_read error while parsing (offset: 0x%X)!\n",
 229                                offset);
 230                         continue;
 231                 }
 232
 233                 /* Some devices (ex. WNDR3700v3) don't have a standard 'MPFR' */
 234                 if (buf[0x000 / 4] == BOARD_DATA_MAGIC2) {
 235                         bcm47xxpart_add_part(&parts[curr_part++], "board_data",
 236                                              offset, MTD_WRITEABLE);
 237                         continue;
 238                 }
 239         }
 240
 241         /* Look for NVRAM at the end of the last block. */
 242         for (i = 0; i < ARRAY_SIZE(possible_nvram_sizes); i++) {
 243                 if (curr_part >= BCM47XXPART_MAX_PARTS) {
 244                         pr_warn("Reached maximum number of partitions, scanning stopped!\n");
 245                         break;
 246                 }
 247
 248                 offset = master->size - possible_nvram_sizes[i];
 249                 if (mtd_read(master, offset, 0x4, &bytes_read,
 250                              (uint8_t *)buf) < 0) {
 251                         pr_err("mtd_read error while reading at offset 0x%X!\n",
 252                                offset);
 253                         continue;
 254                 }
 255
 256                 /* Standard NVRAM */
 257                 if (buf[0] == NVRAM_HEADER) {
 258                         bcm47xxpart_add_part(&parts[curr_part++], "nvram",
 259                                              master->size - blocksize, 0);
 260                         break;
 261                 }
 262         }
 263
 264         kfree(buf);
 265
 266         /*
 267          * Assume that partitions end at the beginning of the one they are
 268          * followed by.
 269          */
 270         for (i = 0; i < curr_part; i++) {
 271                 u64 next_part_offset = (i < curr_part - 1) ?
 272                                        parts[i + 1].offset : master->size;
 273
 274                 parts[i].size = next_part_offset - parts[i].offset;
 275                 if (i == last_trx_part && trx_part >= 0)
 276                         parts[trx_part].size = next_part_offset -
 277                                                parts[trx_part].offset;
 278         }
 279
 280         *pparts = parts;
 281         return curr_part;
 282 };
 283
 284 static struct mtd_part_parser bcm47xxpart_mtd_parser = {
 285         .owner = THIS_MODULE,
 286         .parse_fn = bcm47xxpart_parse,
 287         .name = "bcm47xxpart",
 288 };
 289
 290 static int __init bcm47xxpart_init(void)
 291 {
 292         register_mtd_parser(&bcm47xxpart_mtd_parser);
 293         return 0;
 294 }
 295
 296 static void __exit bcm47xxpart_exit(void)
 297 {
 298         deregister_mtd_parser(&bcm47xxpart_mtd_parser);
 299 }
 300
 301 module_init(bcm47xxpart_init);
 302 module_exit(bcm47xxpart_exit);
 303
 304 MODULE_LICENSE("GPL");
 305 MODULE_DESCRIPTION("MTD partitioning for BCM47XX flash memories");