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

   1 /*
   2  *  Copyright (C) 2012 John Crispin <blogic@openwrt.org>
   3  *  Copyright (C) 2015 Martin Blumenstingl <martin.blumenstingl@googlemail.com>
   4  *
   5  *  This program is free software; you can redistribute it and/or modify it
   6  *  under the terms of the GNU General Public License version 2 as published
   7  *  by the Free Software Foundation.
   8  *
   9  */
  10
  11 #include <linux/module.h>
  12 #include <linux/init.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 <linux/byteorder/generic.h>
  18
  19 #include "mtdsplit.h"
  20
  21 #define BRNIMAGE_NR_PARTS       2
  22
  23 #define BRNIMAGE_ALIGN_BYTES    0x400
  24 #define BRNIMAGE_FOOTER_SIZE    12
  25
  26 #define BRNIMAGE_MIN_OVERHEAD   (BRNIMAGE_FOOTER_SIZE)
  27 #define BRNIMAGE_MAX_OVERHEAD   (BRNIMAGE_ALIGN_BYTES + BRNIMAGE_FOOTER_SIZE)
  28
  29 static int mtdsplit_parse_brnimage(struct mtd_info *master,
  30                                 const struct mtd_partition **pparts,
  31                                 struct mtd_part_parser_data *data)
  32 {
  33         struct mtd_partition *parts;
  34         uint32_t buf;
  35         unsigned long rootfs_offset, rootfs_size, kernel_size;
  36         size_t len;
  37         int ret = 0;
  38
  39         for (rootfs_offset = 0; rootfs_offset < master->size;
  40              rootfs_offset += BRNIMAGE_ALIGN_BYTES) {
  41                 ret = mtd_check_rootfs_magic(master, rootfs_offset, NULL);
  42                 if (!ret)
  43                         break;
  44         }
  45
  46         if (ret)
  47                 return ret;
  48
  49         if (rootfs_offset >= master->size)
  50                 return -EINVAL;
  51
  52         ret = mtd_read(master, rootfs_offset - BRNIMAGE_FOOTER_SIZE, 4, &len,
  53                         (void *)&buf);
  54         if (ret)
  55                 return ret;
  56
  57         if (len != 4)
  58                 return -EIO;
  59
  60         kernel_size = le32_to_cpu(buf);
  61
  62         if (kernel_size > (rootfs_offset - BRNIMAGE_MIN_OVERHEAD))
  63                 return -EINVAL;
  64
  65         if (kernel_size < (rootfs_offset - BRNIMAGE_MAX_OVERHEAD))
  66                 return -EINVAL;
  67
  68         /*
  69          * The footer must be untouched as it contains the checksum of the
  70          * original brnImage (kernel + squashfs)!
  71          */
  72         rootfs_size = master->size - rootfs_offset - BRNIMAGE_FOOTER_SIZE;
  73
  74         parts = kzalloc(BRNIMAGE_NR_PARTS * sizeof(*parts), GFP_KERNEL);
  75         if (!parts)
  76                 return -ENOMEM;
  77
  78         parts[0].name = KERNEL_PART_NAME;
  79         parts[0].offset = 0;
  80         parts[0].size = kernel_size;
  81
  82         parts[1].name = ROOTFS_PART_NAME;
  83         parts[1].offset = rootfs_offset;
  84         parts[1].size = rootfs_size;
  85
  86         *pparts = parts;
  87         return BRNIMAGE_NR_PARTS;
  88 }
  89
  90 static struct mtd_part_parser mtdsplit_brnimage_parser = {
  91         .owner = THIS_MODULE,
  92         .name = "brnimage-fw",
  93         .parse_fn = mtdsplit_parse_brnimage,
  94         .type = MTD_PARSER_TYPE_FIRMWARE,
  95 };
  96
  97 static int __init mtdsplit_brnimage_init(void)
  98 {
  99         register_mtd_parser(&mtdsplit_brnimage_parser);
 100
 101         return 0;
 102 }
 103
 104 subsys_initcall(mtdsplit_brnimage_init);