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