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