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 #include <bcm47xx_nvram.h>
  18
  19 /* 10 parts were found on sflash on Netgear WNDR4500 */
  20 #define BCM47XXPART_MAX_PARTS           12
  21
  22 /*
  23  * Amount of bytes we read when analyzing each block of flash memory.
  24  * Set it big enough to allow detecting partition and reading important data.
  25  */
  26 #define BCM47XXPART_BYTES_TO_READ       0x404
  27
  28 /* Magics */
  29 #define BOARD_DATA_MAGIC                0x5246504D      /* MPFR */
  30 #define FACTORY_MAGIC                   0x59544346      /* FCTY */
  31 #define POT_MAGIC1                      0x54544f50      /* POTT */
  32 #define POT_MAGIC2                      0x504f          /* OP */
  33 #define ML_MAGIC1                       0x39685a42
  34 #define ML_MAGIC2                       0x26594131
  35 #define TRX_MAGIC                       0x30524448
  36 #define SQSH_MAGIC                      0x71736873      /* shsq */
  37
  38 struct trx_header {
  39         uint32_t magic;
  40         uint32_t length;
  41         uint32_t crc32;
  42         uint16_t flags;
  43         uint16_t version;
  44         uint32_t offset[3];
  45 } __packed;
  46
  47 static void bcm47xxpart_add_part(struct mtd_partition *part, char *name,
  48                                  u64 offset, uint32_t mask_flags)
  49 {
  50         part->name = name;
  51         part->offset = offset;
  52         part->mask_flags = mask_flags;
  53 }
  54
  55 static int bcm47xxpart_parse(struct mtd_info *master,
  56                              struct mtd_partition **pparts,
  57                              struct mtd_part_parser_data *data)
  58 {
  59         struct mtd_partition *parts;
  60         uint8_t i, curr_part = 0;
  61         uint32_t *buf;
  62         size_t bytes_read;
  63         uint32_t offset;
  64         uint32_t blocksize = master->erasesize;
  65         struct trx_header *trx;
  66         int trx_part = -1;
  67         int last_trx_part = -1;
  68         int possible_nvram_sizes[] = { 0x8000, 0xF000, 0x10000, };
  69
  70         if (blocksize <= 0x10000)
  71                 blocksize = 0x10000;
  72
  73         /* Alloc */
  74         parts = kzalloc(sizeof(struct mtd_partition) * BCM47XXPART_MAX_PARTS,
  75                         GFP_KERNEL);
  76         if (!parts)
  77                 return -ENOMEM;
  78
  79         buf = kzalloc(BCM47XXPART_BYTES_TO_READ, GFP_KERNEL);
  80         if (!buf) {
  81                 kfree(parts);
  82                 return -ENOMEM;
  83         }
  84
  85         /* Parse block by block looking for magics */
  86         for (offset = 0; offset <= master->size - blocksize;
  87              offset += blocksize) {
  88                 /* Nothing more in higher memory */
  89                 if (offset >= 0x2000000)
  90                         break;
  91
  92                 if (curr_part > BCM47XXPART_MAX_PARTS) {
  93                         pr_warn("Reached maximum number of partitions, scanning stopped!\n");
  94                         break;
  95                 }
  96
  97                 /* Read beginning of the block */
  98                 if (mtd_read(master, offset, BCM47XXPART_BYTES_TO_READ,
  99                              &bytes_read, (uint8_t *)buf) < 0) {
 100                         pr_err("mtd_read error while parsing (offset: 0x%X)!\n",
 101                                offset);
 102                         continue;
 103                 }
 104
 105                 /* CFE has small NVRAM at 0x400 */
 106                 if (buf[0x400 / 4] == NVRAM_HEADER) {
 107                         bcm47xxpart_add_part(&parts[curr_part++], "boot",
 108                                              offset, MTD_WRITEABLE);
 109                         continue;
 110                 }
 111
 112                 /*
 113                  * board_data starts with board_id which differs across boards,
 114                  * but we can use 'MPFR' (hopefully) magic at 0x100
 115                  */
 116                 if (buf[0x100 / 4] == BOARD_DATA_MAGIC) {
 117                         bcm47xxpart_add_part(&parts[curr_part++], "board_data",
 118                                              offset, MTD_WRITEABLE);
 119                         continue;
 120                 }
 121
 122                 /* Found on Huawei E970 */
 123                 if (buf[0x000 / 4] == FACTORY_MAGIC) {
 124                         bcm47xxpart_add_part(&parts[curr_part++], "factory",
 125                                              offset, MTD_WRITEABLE);
 126                         continue;
 127                 }
 128
 129                 /* POT(TOP) */
 130                 if (buf[0x000 / 4] == POT_MAGIC1 &&
 131                     (buf[0x004 / 4] & 0xFFFF) == POT_MAGIC2) {
 132                         bcm47xxpart_add_part(&parts[curr_part++], "POT", offset,
 133                                              MTD_WRITEABLE);
 134                         continue;
 135                 }
 136
 137                 /* ML */
 138                 if (buf[0x010 / 4] == ML_MAGIC1 &&
 139                     buf[0x014 / 4] == ML_MAGIC2) {
 140                         bcm47xxpart_add_part(&parts[curr_part++], "ML", offset,
 141                                              MTD_WRITEABLE);
 142                         continue;
 143                 }
 144
 145                 /* TRX */
 146                 if (buf[0x000 / 4] == TRX_MAGIC) {
 147                         trx = (struct trx_header *)buf;
 148
 149                         trx_part = curr_part;
 150                         bcm47xxpart_add_part(&parts[curr_part++], "firmware",
 151                                              offset, 0);
 152
 153                         i = 0;
 154                         /* We have LZMA loader if offset[2] points to sth */
 155                         if (trx->offset[2]) {
 156                                 bcm47xxpart_add_part(&parts[curr_part++],
 157                                                      "loader",
 158                                                      offset + trx->offset[i],
 159                                                      0);
 160                                 i++;
 161                         }
 162
 163                         bcm47xxpart_add_part(&parts[curr_part++], "linux",
 164                                              offset + trx->offset[i], 0);
 165                         i++;
 166
 167                         /*
 168                          * Pure rootfs size is known and can be calculated as:
 169                          * trx->length - trx->offset[i]. We don't fill it as
 170                          * we want to have jffs2 (overlay) in the same mtd.
 171                          */
 172                         bcm47xxpart_add_part(&parts[curr_part++], "rootfs",
 173                                              offset + trx->offset[i], 0);
 174                         i++;
 175
 176                         last_trx_part = curr_part - 1;
 177
 178                         /*
 179                          * We have whole TRX scanned, skip to the next part. Use
 180                          * roundown (not roundup), as the loop will increase
 181                          * offset in next step.
 182                          */
 183                         offset = rounddown(offset + trx->length, blocksize);
 184                         continue;
 185                 }
 186
 187                 /* Squashfs on devices not using TRX */
 188                 if (buf[0x000 / 4] == SQSH_MAGIC) {
 189                         bcm47xxpart_add_part(&parts[curr_part++], "rootfs",
 190                                              offset, 0);
 191                         continue;
 192                 }
 193         }
 194
 195         /* Look for NVRAM at the end of the last block. */
 196         for (i = 0; i < ARRAY_SIZE(possible_nvram_sizes); i++) {
 197                 if (curr_part > BCM47XXPART_MAX_PARTS) {
 198                         pr_warn("Reached maximum number of partitions, scanning stopped!\n");
 199                         break;
 200                 }
 201
 202                 offset = master->size - possible_nvram_sizes[i];
 203                 if (mtd_read(master, offset, 0x4, &bytes_read,
 204                              (uint8_t *)buf) < 0) {
 205                         pr_err("mtd_read error while reading at offset 0x%X!\n",
 206                                offset);
 207                         continue;
 208                 }
 209
 210                 /* Standard NVRAM */
 211                 if (buf[0] == NVRAM_HEADER) {
 212                         bcm47xxpart_add_part(&parts[curr_part++], "nvram",
 213                                              master->size - blocksize, 0);
 214                         break;
 215                 }
 216         }
 217
 218         kfree(buf);
 219
 220         /*
 221          * Assume that partitions end at the beginning of the one they are
 222          * followed by.
 223          */
 224         for (i = 0; i < curr_part; i++) {
 225                 u64 next_part_offset = (i < curr_part - 1) ?
 226                                        parts[i + 1].offset : master->size;
 227
 228                 parts[i].size = next_part_offset - parts[i].offset;
 229                 if (i == last_trx_part && trx_part >= 0)
 230                         parts[trx_part].size = next_part_offset -
 231                                                parts[trx_part].offset;
 232         }
 233
 234         *pparts = parts;
 235         return curr_part;
 236 };
 237
 238 static struct mtd_part_parser bcm47xxpart_mtd_parser = {
 239         .owner = THIS_MODULE,
 240         .parse_fn = bcm47xxpart_parse,
 241         .name = "bcm47xxpart",
 242 };
 243
 244 static int __init bcm47xxpart_init(void)
 245 {
 246         return register_mtd_parser(&bcm47xxpart_mtd_parser);
 247 }
 248
 249 static void __exit bcm47xxpart_exit(void)
 250 {
 251         deregister_mtd_parser(&bcm47xxpart_mtd_parser);
 252 }
 253
 254 module_init(bcm47xxpart_init);
 255 module_exit(bcm47xxpart_exit);
 256
 257 MODULE_LICENSE("GPL");
 258 MODULE_DESCRIPTION("MTD partitioning for BCM47XX flash memories");