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 /* Magics */
  23 #define BOARD_DATA_MAGIC                0x5246504D      /* MPFR */
  24 #define POT_MAGIC1                      0x54544f50      /* POTT */
  25 #define POT_MAGIC2                      0x504f          /* OP */
  26 #define ML_MAGIC1                       0x39685a42
  27 #define ML_MAGIC2                       0x26594131
  28 #define TRX_MAGIC                       0x30524448
  29
  30 struct trx_header {
  31         uint32_t magic;
  32         uint32_t length;
  33         uint32_t crc32;
  34         uint16_t flags;
  35         uint16_t version;
  36         uint32_t offset[3];
  37 } __packed;
  38
  39 static void bcm47xxpart_add_part(struct mtd_partition *part, char *name,
  40                                  u64 offset, uint32_t mask_flags)
  41 {
  42         part->name = name;
  43         part->offset = offset;
  44         part->mask_flags = mask_flags;
  45 }
  46
  47 static int bcm47xxpart_parse(struct mtd_info *master,
  48                              struct mtd_partition **pparts,
  49                              struct mtd_part_parser_data *data)
  50 {
  51         struct mtd_partition *parts;
  52         uint8_t i, curr_part = 0;
  53         uint32_t *buf;
  54         size_t bytes_read;
  55         uint32_t offset;
  56         uint32_t blocksize = master->erasesize;
  57         struct trx_header *trx;
  58         int trx_part = -1;
  59         int last_trx_part = -1;
  60         int max_bytes_to_read = 0x8004;
  61
  62         if (blocksize <= 0x10000)
  63                 blocksize = 0x10000;
  64         if (blocksize == 0x20000)
  65                 max_bytes_to_read = 0x18004;
  66
  67         /* Alloc */
  68         parts = kzalloc(sizeof(struct mtd_partition) * BCM47XXPART_MAX_PARTS,
  69                         GFP_KERNEL);
  70         buf = kzalloc(max_bytes_to_read, GFP_KERNEL);
  71
  72         /* Parse block by block looking for magics */
  73         for (offset = 0; offset <= master->size - blocksize;
  74              offset += blocksize) {
  75                 /* Nothing more in higher memory */
  76                 if (offset >= 0x2000000)
  77                         break;
  78
  79                 if (curr_part > BCM47XXPART_MAX_PARTS) {
  80                         pr_warn("Reached maximum number of partitions, scanning stopped!\n");
  81                         break;
  82                 }
  83
  84                 /* Read beginning of the block */
  85                 if (mtd_read(master, offset, max_bytes_to_read,
  86                              &bytes_read, (uint8_t *)buf) < 0) {
  87                         pr_err("mtd_read error while parsing (offset: 0x%X)!\n",
  88                                offset);
  89                         continue;
  90                 }
  91
  92                 /* CFE has small NVRAM at 0x400 */
  93                 if (buf[0x400 / 4] == NVRAM_HEADER) {
  94                         bcm47xxpart_add_part(&parts[curr_part++], "boot",
  95                                              offset, MTD_WRITEABLE);
  96                         continue;
  97                 }
  98
  99                 /* Standard NVRAM */
 100                 if (buf[0x000 / 4] == NVRAM_HEADER ||
 101                     buf[0x1000 / 4] == NVRAM_HEADER ||
 102                     buf[0x8000 / 4] == NVRAM_HEADER ||
 103                     (blocksize == 0x20000 && (
 104                       buf[0x10000 / 4] == NVRAM_HEADER ||
 105                       buf[0x11000 / 4] == NVRAM_HEADER ||
 106                       buf[0x18000 / 4] == NVRAM_HEADER))) {
 107                         bcm47xxpart_add_part(&parts[curr_part++], "nvram",
 108                                              offset, 0);
 109                         offset = rounddown(offset, blocksize);
 110                         continue;
 111                 }
 112
 113                 /*
 114                  * board_data starts with board_id which differs across boards,
 115                  * but we can use 'MPFR' (hopefully) magic at 0x100
 116                  */
 117                 if (buf[0x100 / 4] == BOARD_DATA_MAGIC) {
 118                         bcm47xxpart_add_part(&parts[curr_part++], "board_data",
 119                                              offset, MTD_WRITEABLE);
 120                         continue;
 121                 }
 122
 123                 /* POT(TOP) */
 124                 if (buf[0x000 / 4] == POT_MAGIC1 &&
 125                     (buf[0x004 / 4] & 0xFFFF) == POT_MAGIC2) {
 126                         bcm47xxpart_add_part(&parts[curr_part++], "POT", offset,
 127                                              MTD_WRITEABLE);
 128                         continue;
 129                 }
 130
 131                 /* ML */
 132                 if (buf[0x010 / 4] == ML_MAGIC1 &&
 133                     buf[0x014 / 4] == ML_MAGIC2) {
 134                         bcm47xxpart_add_part(&parts[curr_part++], "ML", offset,
 135                                              MTD_WRITEABLE);
 136                         continue;
 137                 }
 138
 139                 /* TRX */
 140                 if (buf[0x000 / 4] == TRX_MAGIC) {
 141                         trx = (struct trx_header *)buf;
 142
 143                         trx_part = curr_part;
 144                         bcm47xxpart_add_part(&parts[curr_part++], "firmware",
 145                                              offset, 0);
 146
 147                         i = 0;
 148                         /* We have LZMA loader if offset[2] points to sth */
 149                         if (trx->offset[2]) {
 150                                 bcm47xxpart_add_part(&parts[curr_part++],
 151                                                      "loader",
 152                                                      offset + trx->offset[i],
 153                                                      0);
 154                                 i++;
 155                         }
 156
 157                         bcm47xxpart_add_part(&parts[curr_part++], "linux",
 158                                              offset + trx->offset[i], 0);
 159                         i++;
 160
 161                         /*
 162                          * Pure rootfs size is known and can be calculated as:
 163                          * trx->length - trx->offset[i]. We don't fill it as
 164                          * we want to have jffs2 (overlay) in the same mtd.
 165                          */
 166                         bcm47xxpart_add_part(&parts[curr_part++], "rootfs",
 167                                              offset + trx->offset[i], 0);
 168                         i++;
 169
 170                         last_trx_part = curr_part - 1;
 171
 172                         /*
 173                          * We have whole TRX scanned, skip to the next part. Use
 174                          * roundown (not roundup), as the loop will increase
 175                          * offset in next step.
 176                          */
 177                         offset = rounddown(offset + trx->length, blocksize);
 178                         continue;
 179                 }
 180         }
 181         kfree(buf);
 182
 183         /*
 184          * Assume that partitions end at the beginning of the one they are
 185          * followed by.
 186          */
 187         for (i = 0; i < curr_part; i++) {
 188                 u64 next_part_offset = (i < curr_part - 1) ?
 189                                        parts[i + 1].offset : master->size;
 190
 191                 parts[i].size = next_part_offset - parts[i].offset;
 192                 if (i == last_trx_part && trx_part >= 0)
 193                         parts[trx_part].size = next_part_offset -
 194                                                parts[trx_part].offset;
 195         }
 196
 197         *pparts = parts;
 198         return curr_part;
 199 };
 200
 201 static struct mtd_part_parser bcm47xxpart_mtd_parser = {
 202         .owner = THIS_MODULE,
 203         .parse_fn = bcm47xxpart_parse,
 204         .name = "bcm47xxpart",
 205 };
 206
 207 static int __init bcm47xxpart_init(void)
 208 {
 209         return register_mtd_parser(&bcm47xxpart_mtd_parser);
 210 }
 211
 212 static void __exit bcm47xxpart_exit(void)
 213 {
 214         deregister_mtd_parser(&bcm47xxpart_mtd_parser);
 215 }
 216
 217 module_init(bcm47xxpart_init);
 218 module_exit(bcm47xxpart_exit);
 219
 220 MODULE_LICENSE("GPL");
 221 MODULE_DESCRIPTION("MTD partitioning for BCM47XX flash memories");