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 <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
  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 = 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
 182static struct mtd_part_parser bcm47xxpart_mtd_parser = {
 183        .owner = THIS_MODULE,
 184        .parse_fn = bcm47xxpart_parse,
 185        .name = "bcm47xxpart",
 186};
 187
 188static int __init bcm47xxpart_init(void)
 189{
 190        return register_mtd_parser(&bcm47xxpart_mtd_parser);
 191}
 192
 193static void __exit bcm47xxpart_exit(void)
 194{
 195        deregister_mtd_parser(&bcm47xxpart_mtd_parser);
 196}
 197
 198module_init(bcm47xxpart_init);
 199module_exit(bcm47xxpart_exit);
 200
 201MODULE_LICENSE("GPL");
 202MODULE_DESCRIPTION("MTD partitioning for BCM47XX flash memories");
 203
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