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 <asm/mach-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 = 0x10000;
  63         struct trx_header *trx;
  64
  65         /* Alloc */
  66         parts = kzalloc(sizeof(struct mtd_partition) * BCM47XXPART_MAX_PARTS,
  67                         GFP_KERNEL);
  68         buf = kzalloc(BCM47XXPART_BYTES_TO_READ, GFP_KERNEL);
  69
  70         /* Parse block by block looking for magics */
  71         for (offset = 0; offset <= master->size - blocksize;
  72              offset += blocksize) {
  73                 /* Nothing more in higher memory */
  74                 if (offset >= 0x2000000)
  75                         break;
  76
  77                 if (curr_part > BCM47XXPART_MAX_PARTS) {
  78                         pr_warn("Reached maximum number of partitions, scanning stopped!\n");
  79                         break;
  80                 }
  81
  82                 /* Read beginning of the block */
  83                 if (mtd_read(master, offset, BCM47XXPART_BYTES_TO_READ,
  84                              &bytes_read, (uint8_t *)buf) < 0) {
  85                         pr_err("mtd_read error while parsing (offset: 0x%X)!\n",
  86                                offset);
  87                         continue;
  88                 }
  89
  90                 /* CFE has small NVRAM at 0x400 */
  91                 if (buf[0x400 / 4] == NVRAM_HEADER) {
  92                         bcm47xxpart_add_part(&parts[curr_part++], "boot",
  93                                              offset, MTD_WRITEABLE);
  94                         continue;
  95                 }
  96
  97                 /* Standard NVRAM */
  98                 if (buf[0x000 / 4] == NVRAM_HEADER) {
  99                         bcm47xxpart_add_part(&parts[curr_part++], "nvram",
 100                                              offset, 0);
 101                         continue;
 102                 }
 103
 104                 /*
 105                  * board_data starts with board_id which differs across boards,
 106                  * but we can use 'MPFR' (hopefully) magic at 0x100
 107                  */
 108                 if (buf[0x100 / 4] == BOARD_DATA_MAGIC) {
 109                         bcm47xxpart_add_part(&parts[curr_part++], "board_data",
 110                                              offset, MTD_WRITEABLE);
 111                         continue;
 112                 }
 113
 114                 /* POT(TOP) */
 115                 if (buf[0x000 / 4] == POT_MAGIC1 &&
 116                     (buf[0x004 / 4] & 0xFFFF) == POT_MAGIC2) {
 117                         bcm47xxpart_add_part(&parts[curr_part++], "POT", offset,
 118                                              MTD_WRITEABLE);
 119                         continue;
 120                 }
 121
 122                 /* ML */
 123                 if (buf[0x010 / 4] == ML_MAGIC1 &&
 124                     buf[0x014 / 4] == ML_MAGIC2) {
 125                         bcm47xxpart_add_part(&parts[curr_part++], "ML", offset,
 126                                              MTD_WRITEABLE);
 127                         continue;
 128                 }
 129
 130                 /* TRX */
 131                 if (buf[0x000 / 4] == TRX_MAGIC) {
 132                         trx = (struct trx_header *)buf;
 133
 134                         i = 0;
 135                         /* We have LZMA loader if offset[2] points to sth */
 136                         if (trx->offset[2]) {
 137                                 bcm47xxpart_add_part(&parts[curr_part++],
 138                                                      "loader",
 139                                                      offset + trx->offset[i],
 140                                                      0);
 141                                 i++;
 142                         }
 143
 144                         bcm47xxpart_add_part(&parts[curr_part++], "linux",
 145                                              offset + trx->offset[i], 0);
 146                         i++;
 147
 148                         /*
 149                          * Pure rootfs size is known and can be calculated as:
 150                          * trx->length - trx->offset[i]. We don't fill it as
 151                          * we want to have jffs2 (overlay) in the same mtd.
 152                          */
 153                         bcm47xxpart_add_part(&parts[curr_part++], "rootfs",
 154                                              offset + trx->offset[i], 0);
 155                         i++;
 156
 157                         /*
 158                          * We have whole TRX scanned, skip to the next part. Use
 159                          * roundown (not roundup), as the loop will increase
 160                          * offset in next step.
 161                          */
 162                         offset = rounddown(offset + trx->length, blocksize);
 163                         continue;
 164                 }
 165         }
 166         kfree(buf);
 167
 168         /*
 169          * Assume that partitions end at the beginning of the one they are
 170          * followed by.
 171          */
 172         for (i = 0; i < curr_part - 1; i++)
 173                 parts[i].size = parts[i + 1].offset - parts[i].offset;
 174         if (curr_part > 0)
 175                 parts[curr_part - 1].size =
 176                                 master->size - parts[curr_part - 1].offset;
 177
 178         *pparts = parts;
 179         return curr_part;
 180 };
 181
 182 static struct mtd_part_parser bcm47xxpart_mtd_parser = {
 183         .owner = THIS_MODULE,
 184         .parse_fn = bcm47xxpart_parse,
 185         .name = "bcm47xxpart",
 186 };
 187
 188 static int __init bcm47xxpart_init(void)
 189 {
 190         return register_mtd_parser(&bcm47xxpart_mtd_parser);
 191 }
 192
 193 static void __exit bcm47xxpart_exit(void)
 194 {
 195         deregister_mtd_parser(&bcm47xxpart_mtd_parser);
 196 }
 197
 198 module_init(bcm47xxpart_init);
 199 module_exit(bcm47xxpart_exit);
 200
 201 MODULE_LICENSE("GPL");
 202 MODULE_DESCRIPTION("MTD partitioning for BCM47XX flash memories");