target/linux/generic/files/drivers/mtd/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 };
  30
  31 static int mtdsplit_parse_seama(struct mtd_info *master,
  32                                 struct mtd_partition **pparts,
  33                                 struct mtd_part_parser_data *data)
  34 {
  35         struct seama_header hdr;
  36         size_t hdr_len, retlen, kernel_size;
  37         size_t rootfs_offset;
  38         struct mtd_partition *parts;
  39         int err;
  40
  41         hdr_len = sizeof(hdr);
  42         err = mtd_read(master, 0, hdr_len, &retlen, (void *) &hdr);
  43         if (err)
  44                 return err;
  45
  46         if (retlen != hdr_len)
  47                 return -EIO;
  48
  49         /* sanity checks */
  50         if (be32_to_cpu(hdr.magic) != SEAMA_MAGIC)
  51                 return -EINVAL;
  52
  53         kernel_size = hdr_len + be32_to_cpu(hdr.size) +
  54                       be16_to_cpu(hdr.metasize);
  55         if (kernel_size > master->size)
  56                 return -EINVAL;
  57
  58         /* Find the rootfs after the kernel. */
  59         err = mtd_check_rootfs_magic(master, kernel_size);
  60         if (!err) {
  61                 rootfs_offset = kernel_size;
  62         } else {
  63                 /*
  64                  * The size in the header might cover the rootfs as well.
  65                  * Start the search from an arbitrary offset.
  66                  */
  67                 err = mtd_find_rootfs_from(master, SEAMA_MIN_ROOTFS_OFFS,
  68                                            master->size, &rootfs_offset);
  69                 if (err)
  70                         return err;
  71         }
  72
  73         parts = kzalloc(SEAMA_NR_PARTS * sizeof(*parts), GFP_KERNEL);
  74         if (!parts)
  75                 return -ENOMEM;
  76
  77         parts[0].name = KERNEL_PART_NAME;
  78         parts[0].offset = 0;
  79         parts[0].size = rootfs_offset;
  80
  81         parts[1].name = ROOTFS_PART_NAME;
  82         parts[1].offset = rootfs_offset;
  83         parts[1].size = master->size - rootfs_offset;
  84
  85         *pparts = parts;
  86         return SEAMA_NR_PARTS;
  87 }
  88
  89 static struct mtd_part_parser mtdsplit_seama_parser = {
  90         .owner = THIS_MODULE,
  91         .name = "seama-fw",
  92         .parse_fn = mtdsplit_parse_seama,
  93         .type = MTD_PARSER_TYPE_FIRMWARE,
  94 };
  95
  96 static int __init mtdsplit_seama_init(void)
  97 {
  98         register_mtd_parser(&mtdsplit_seama_parser);
  99
 100         return 0;
 101 }
 102
 103 subsys_initcall(mtdsplit_seama_init);