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 #include <linux/of.h>
  18
  19 #include "mtdsplit.h"
  20
  21 #define SEAMA_MAGIC             0x5EA3A417
  22 #define SEAMA_NR_PARTS          2
  23 #define SEAMA_MIN_ROOTFS_OFFS   0x80000 /* 512KiB */
  24
  25 struct seama_header {
  26         __be32  magic;          /* should always be SEAMA_MAGIC. */
  27         __be16  reserved;       /* reserved for  */
  28         __be16  metasize;       /* size of the META data */
  29         __be32  size;           /* size of the image */
  30         u8      md5[16];        /* digest */
  31 };
  32
  33 static int mtdsplit_parse_seama(struct mtd_info *master,
  34                                 const struct mtd_partition **pparts,
  35                                 struct mtd_part_parser_data *data)
  36 {
  37         struct seama_header hdr;
  38         size_t hdr_len, retlen, kernel_ent_size;
  39         size_t rootfs_offset;
  40         struct mtd_partition *parts;
  41         enum mtdsplit_part_type type;
  42         int err;
  43
  44         hdr_len = sizeof(hdr);
  45         err = mtd_read(master, 0, hdr_len, &retlen, (void *) &hdr);
  46         if (err)
  47                 return err;
  48
  49         if (retlen != hdr_len)
  50                 return -EIO;
  51
  52         /* sanity checks */
  53         if (be32_to_cpu(hdr.magic) != SEAMA_MAGIC)
  54                 return -EINVAL;
  55
  56         kernel_ent_size = hdr_len + be32_to_cpu(hdr.size) +
  57                           be16_to_cpu(hdr.metasize);
  58         if (kernel_ent_size > master->size)
  59                 return -EINVAL;
  60
  61         /* Check for the rootfs right after Seama entity with a kernel. */
  62         err = mtd_check_rootfs_magic(master, kernel_ent_size, &type);
  63         if (!err) {
  64                 rootfs_offset = kernel_ent_size;
  65         } else {
  66                 /*
  67                  * On some devices firmware entity might contain both: kernel
  68                  * and rootfs. We can't determine kernel size so we just have to
  69                  * look for rootfs magic.
  70                  * Start the search from an arbitrary offset.
  71                  */
  72                 err = mtd_find_rootfs_from(master, SEAMA_MIN_ROOTFS_OFFS,
  73                                            master->size, &rootfs_offset, &type);
  74                 if (err)
  75                         return err;
  76         }
  77
  78         parts = kzalloc(SEAMA_NR_PARTS * sizeof(*parts), GFP_KERNEL);
  79         if (!parts)
  80                 return -ENOMEM;
  81
  82         parts[0].name = KERNEL_PART_NAME;
  83         parts[0].offset = sizeof hdr + be16_to_cpu(hdr.metasize);
  84         parts[0].size = rootfs_offset - parts[0].offset;
  85
  86         if (type == MTDSPLIT_PART_TYPE_UBI)
  87                 parts[1].name = UBI_PART_NAME;
  88         else
  89                 parts[1].name = ROOTFS_PART_NAME;
  90         parts[1].offset = rootfs_offset;
  91         parts[1].size = master->size - rootfs_offset;
  92
  93         *pparts = parts;
  94         return SEAMA_NR_PARTS;
  95 }
  96
  97 static const struct of_device_id mtdsplit_seama_of_match_table[] = {
  98         { .compatible = "seama" },
  99         {},
 100 };
 101 MODULE_DEVICE_TABLE(of, mtdsplit_seama_of_match_table);
 102
 103 static struct mtd_part_parser mtdsplit_seama_parser = {
 104         .owner = THIS_MODULE,
 105         .name = "seama-fw",
 106         .of_match_table = mtdsplit_seama_of_match_table,
 107         .parse_fn = mtdsplit_parse_seama,
 108         .type = MTD_PARSER_TYPE_FIRMWARE,
 109 };
 110
 111 static int __init mtdsplit_seama_init(void)
 112 {
 113         register_mtd_parser(&mtdsplit_seama_parser);
 114
 115         return 0;
 116 }
 117
 118 subsys_initcall(mtdsplit_seama_init);