target/linux/generic/files/drivers/mtd/mtdsplit/mtdsplit_seama.c

   1 /*
   2  *  Copyright (C) 2013 Gabor Juhos <juhosg@openwrt.org>
   3  *
   4  *  This program is free software; you can redistribute it and/or modify it
   5  *  under the terms of the GNU General Public License version 2 as published
   6  *  by the Free Software Foundation.
   7  *
   8  */
   9
  10 #include <linux/module.h>
  11 #include <linux/init.h>
  12 #include <linux/kernel.h>
  13 #include <linux/slab.h>
  14 #include <linux/mtd/mtd.h>
  15 #include <linux/mtd/partitions.h>
  16 #include <linux/byteorder/generic.h>
  17
  18 #include "mtdsplit.h"
  19
  20 #define SEAMA_MAGIC             0x5EA3A417
  21 #define SEAMA_NR_PARTS          2
  22 #define SEAMA_MIN_ROOTFS_OFFS   0x80000 /* 512KiB */
  23
  24 struct seama_header {
  25         __be32  magic;          /* should always be SEAMA_MAGIC. */
  26         __be16  reserved;       /* reserved for  */
  27         __be16  metasize;       /* size of the META data */
  28         __be32  size;           /* size of the image */
  29         u8      md5[16];        /* digest */
  30 };
  31
  32 static int mtdsplit_parse_seama(struct mtd_info *master,
  33                                 const struct mtd_partition **pparts,
  34                                 struct mtd_part_parser_data *data)
  35 {
  36         struct seama_header hdr;
  37         size_t hdr_len, retlen, kernel_ent_size;
  38         size_t rootfs_offset;
  39         struct mtd_partition *parts;
  40         enum mtdsplit_part_type type;
  41         int err;
  42
  43         hdr_len = sizeof(hdr);
  44         err = mtd_read(master, 0, hdr_len, &retlen, (void *) &hdr);
  45         if (err)
  46                 return err;
  47
  48         if (retlen != hdr_len)
  49                 return -EIO;
  50
  51         /* sanity checks */
  52         if (be32_to_cpu(hdr.magic) != SEAMA_MAGIC)
  53                 return -EINVAL;
  54
  55         kernel_ent_size = hdr_len + be32_to_cpu(hdr.size) +
  56                           be16_to_cpu(hdr.metasize);
  57         if (kernel_ent_size > master->size)
  58                 return -EINVAL;
  59
  60         /* Check for the rootfs right after Seama entity with a kernel. */
  61         err = mtd_check_rootfs_magic(master, kernel_ent_size, &type);
  62         if (!err) {
  63                 rootfs_offset = kernel_ent_size;
  64         } else {
  65                 /*
  66                  * On some devices firmware entity might contain both: kernel
  67                  * and rootfs. We can't determine kernel size so we just have to
  68                  * look for rootfs magic.
  69                  * Start the search from an arbitrary offset.
  70                  */
  71                 err = mtd_find_rootfs_from(master, SEAMA_MIN_ROOTFS_OFFS,
  72                                            master->size, &rootfs_offset, &type);
  73                 if (err)
  74                         return err;
  75         }
  76
  77         parts = kzalloc(SEAMA_NR_PARTS * sizeof(*parts), GFP_KERNEL);
  78         if (!parts)
  79                 return -ENOMEM;
  80
  81         parts[0].name = KERNEL_PART_NAME;
  82         parts[0].offset = sizeof hdr + be16_to_cpu(hdr.metasize);
  83         parts[0].size = rootfs_offset - parts[0].offset;
  84
  85         if (type == MTDSPLIT_PART_TYPE_UBI)
  86                 parts[1].name = UBI_PART_NAME;
  87         else
  88                 parts[1].name = ROOTFS_PART_NAME;
  89         parts[1].offset = rootfs_offset;
  90         parts[1].size = master->size - rootfs_offset;
  91
  92         *pparts = parts;
  93         return SEAMA_NR_PARTS;
  94 }
  95
  96 static struct mtd_part_parser mtdsplit_seama_parser = {
  97         .owner = THIS_MODULE,
  98         .name = "seama-fw",
  99         .parse_fn = mtdsplit_parse_seama,
 100         .type = MTD_PARSER_TYPE_FIRMWARE,
 101 };
 102
 103 static int __init mtdsplit_seama_init(void)
 104 {
 105         register_mtd_parser(&mtdsplit_seama_parser);
 106
 107         return 0;
 108 }
 109
 110 subsys_initcall(mtdsplit_seama_init);