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/*
 *  Copyright (C) 2014 Gabor Juhos <juhosg@openwrt.org>
 *
 *  This program is free software; you can redistribute it and/or modify it
 *  under the terms of the GNU General Public License version 2 as published
 *  by the Free Software Foundation.
 *
 */

#include <linux/module.h>
#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/slab.h>
#include <linux/mtd/mtd.h>
#include <linux/mtd/partitions.h>

#include <asm/unaligned.h>

#include "mtdsplit.h"

#define LZMA_NR_PARTS           2
#define LZMA_PROPERTIES_SIZE    5

struct lzma_header {
        u8 props[LZMA_PROPERTIES_SIZE];
        u8 size_low[4];
        u8 size_high[4];
};

static int mtdsplit_parse_lzma(struct mtd_info *master,
                               const struct mtd_partition **pparts,
                               struct mtd_part_parser_data *data)
{
        struct lzma_header hdr;
        size_t hdr_len, retlen;
        size_t rootfs_offset;
        u32 t;
        struct mtd_partition *parts;
        int err;

        hdr_len = sizeof(hdr);
        err = mtd_read(master, 0, hdr_len, &retlen, (void *) &hdr);
        if (err)
                return err;

        if (retlen != hdr_len)
                return -EIO;

        /* verify LZMA properties */
        if (hdr.props[0] >= (9 * 5 * 5))
                return -EINVAL;

        t = get_unaligned_le32(&hdr.props[1]);
        if (!is_power_of_2(t))
                return -EINVAL;

        t = get_unaligned_le32(&hdr.size_high);
        if (t)
                return -EINVAL;

        err = mtd_find_rootfs_from(master, master->erasesize, master->size,
                                   &rootfs_offset, NULL);
        if (err)
                return err;

        parts = kzalloc(LZMA_NR_PARTS * sizeof(*parts), GFP_KERNEL);
        if (!parts)
                return -ENOMEM;

        parts[0].name = KERNEL_PART_NAME;
        parts[0].offset = 0;
        parts[0].size = rootfs_offset;

        parts[1].name = ROOTFS_PART_NAME;
        parts[1].offset = rootfs_offset;
        parts[1].size = master->size - rootfs_offset;

        *pparts = parts;
        return LZMA_NR_PARTS;
}

static const struct of_device_id mtdsplit_lzma_of_match_table[] = {
        { .compatible = "lzma" },
        {},
};
MODULE_DEVICE_TABLE(of, mtdsplit_lzma_of_match_table);

static struct mtd_part_parser mtdsplit_lzma_parser = {
        .owner = THIS_MODULE,
        .name = "lzma-fw",
        .of_match_table = mtdsplit_lzma_of_match_table,
        .parse_fn = mtdsplit_parse_lzma,
        .type = MTD_PARSER_TYPE_FIRMWARE,
};

static int __init mtdsplit_lzma_init(void)
{
        register_mtd_parser(&mtdsplit_lzma_parser);

        return 0;
}

subsys_initcall(mtdsplit_lzma_init);