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