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/*
 *  Parse MyLoader-style flash partition tables and produce a Linux partition
 *  array to match.
 *
 *  Copyright (C) 2007-2009 Gabor Juhos <juhosg@openwrt.org>
 *
 *  This file was based on drivers/mtd/redboot.c
 *  Author: Red Hat, Inc. - David Woodhouse <dwmw2@cambridge.redhat.com>
 *
 *  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/kernel.h>
#include <linux/module.h>
#include <linux/version.h>
#include <linux/slab.h>
#include <linux/init.h>
#include <linux/vmalloc.h>
#include <linux/mtd/mtd.h>
#include <linux/mtd/partitions.h>
#include <linux/byteorder/generic.h>
#include <linux/myloader.h>

#define BLOCK_LEN_MIN           0x10000
#define PART_NAME_LEN           32

struct part_data {
        struct mylo_partition_table     tab;
        char names[MYLO_MAX_PARTITIONS][PART_NAME_LEN];
};

static int myloader_parse_partitions(struct mtd_info *master,
                                     const struct mtd_partition **pparts,
                                     struct mtd_part_parser_data *data)
{
        struct part_data *buf;
        struct mylo_partition_table *tab;
        struct mylo_partition *part;
        struct mtd_partition *mtd_parts;
        struct mtd_partition *mtd_part;
        int num_parts;
        int ret, i;
        size_t retlen;
        char *names;
        unsigned long offset;
        unsigned long blocklen;

        buf = vmalloc(sizeof(*buf));
        if (!buf) {
                return -ENOMEM;
                goto out;
        }
        tab = &buf->tab;

        blocklen = master->erasesize;
        if (blocklen < BLOCK_LEN_MIN)
                blocklen = BLOCK_LEN_MIN;

        offset = blocklen;

        /* Find the partition table */
        for (i = 0; i < 4; i++, offset += blocklen) {
                printk(KERN_DEBUG "%s: searching for MyLoader partition table"
                                " at offset 0x%lx\n", master->name, offset);

                ret = mtd_read(master, offset, sizeof(*buf), &retlen,
                               (void *)buf);
                if (ret)
                        goto out_free_buf;

                if (retlen != sizeof(*buf)) {
                        ret = -EIO;
                        goto out_free_buf;
                }

                /* Check for Partition Table magic number */
                if (tab->magic == le32_to_cpu(MYLO_MAGIC_PARTITIONS))
                        break;

        }

        if (tab->magic != le32_to_cpu(MYLO_MAGIC_PARTITIONS)) {
                printk(KERN_DEBUG "%s: no MyLoader partition table found\n",
                        master->name);
                ret = 0;
                goto out_free_buf;
        }

        /* The MyLoader and the Partition Table is always present */
        num_parts = 2;

        /* Detect number of used partitions */
        for (i = 0; i < MYLO_MAX_PARTITIONS; i++) {
                part = &tab->partitions[i];

                if (le16_to_cpu(part->type) == PARTITION_TYPE_FREE)
                        continue;

                num_parts++;
        }

        mtd_parts = kzalloc((num_parts * sizeof(*mtd_part) +
                                num_parts * PART_NAME_LEN), GFP_KERNEL);

        if (!mtd_parts) {
                ret = -ENOMEM;
                goto out_free_buf;
        }

        mtd_part = mtd_parts;
        names = (char *)&mtd_parts[num_parts];

        strncpy(names, "myloader", PART_NAME_LEN);
        mtd_part->name = names;
        mtd_part->offset = 0;
        mtd_part->size = offset;
        mtd_part->mask_flags = MTD_WRITEABLE;
        mtd_part++;
        names += PART_NAME_LEN;

        strncpy(names, "partition_table", PART_NAME_LEN);
        mtd_part->name = names;
        mtd_part->offset = offset;
        mtd_part->size = blocklen;
        mtd_part->mask_flags = MTD_WRITEABLE;
        mtd_part++;
        names += PART_NAME_LEN;

        for (i = 0; i < MYLO_MAX_PARTITIONS; i++) {
                part = &tab->partitions[i];

                if (le16_to_cpu(part->type) == PARTITION_TYPE_FREE)
                        continue;

                if ((buf->names[i][0]) && (buf->names[i][0] != '\xff'))
                        strncpy(names, buf->names[i], PART_NAME_LEN);
                else
                        snprintf(names, PART_NAME_LEN, "partition%d", i);

                mtd_part->offset = le32_to_cpu(part->addr);
                mtd_part->size = le32_to_cpu(part->size);
                mtd_part->name = names;
                mtd_part++;
                names += PART_NAME_LEN;
        }

        *pparts = mtd_parts;
        ret = num_parts;

 out_free_buf:
        vfree(buf);
 out:
        return ret;
}

static struct mtd_part_parser myloader_mtd_parser = {
        .owner          = THIS_MODULE,
        .parse_fn       = myloader_parse_partitions,
        .name           = "MyLoader",
};

static int __init myloader_mtd_parser_init(void)
{
        register_mtd_parser(&myloader_mtd_parser);

        return 0;
}

static void __exit myloader_mtd_parser_exit(void)
{
        deregister_mtd_parser(&myloader_mtd_parser);
}

module_init(myloader_mtd_parser_init);
module_exit(myloader_mtd_parser_exit);

MODULE_AUTHOR("Gabor Juhos <juhosg@openwrt.org>");
MODULE_DESCRIPTION("Parsing code for MyLoader partition tables");
MODULE_LICENSE("GPL v2");