mtdblock_ro.c

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/*
 * Simple read-only (writable only for RAM) mtdblock driver
 *
 * Copyright © 2001-2010 David Woodhouse <[email protected]>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
 *
 */

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

static int mtdblock_readsect(struct mtd_blktrans_dev *dev,
                  unsigned long block, char *buf)
{
    size_t retlen;

    if (mtd_read(dev->mtd, (block * 512), 512, &retlen, buf))
        return 1;
    return 0;
}

static int mtdblock_writesect(struct mtd_blktrans_dev *dev,
                  unsigned long block, char *buf)
{
    size_t retlen;

    if (mtd_write(dev->mtd, (block * 512), 512, &retlen, buf))
        return 1;
    return 0;
}

static void mtdblock_add_mtd(struct mtd_blktrans_ops *tr, struct mtd_info *mtd)
{
    struct mtd_blktrans_dev *dev = kzalloc(sizeof(*dev), GFP_KERNEL);

    if (!dev)
        return;

    dev->mtd = mtd;
    dev->devnum = mtd->index;

    dev->size = mtd->size >> 9;
    dev->tr = tr;
    dev->readonly = 1;

    if (add_mtd_blktrans_dev(dev))
        kfree(dev);
}

static void mtdblock_remove_dev(struct mtd_blktrans_dev *dev)
{
    del_mtd_blktrans_dev(dev);
}

static struct mtd_blktrans_ops mtdblock_tr = {
    .name       = "mtdblock",
    .major      = 31,
    .part_bits  = 0,
    .blksize    = 512,
    .readsect   = mtdblock_readsect,
    .writesect  = mtdblock_writesect,
    .add_mtd    = mtdblock_add_mtd,
    .remove_dev = mtdblock_remove_dev,
    .owner      = THIS_MODULE,
};

static int __init mtdblock_init(void)
{
    return register_mtd_blktrans(&mtdblock_tr);
}

static void __exit mtdblock_exit(void)
{
    deregister_mtd_blktrans(&mtdblock_tr);
}

module_init(mtdblock_init);
module_exit(mtdblock_exit);

MODULE_LICENSE("GPL");
MODULE_AUTHOR("David Woodhouse <[email protected]>");
MODULE_DESCRIPTION("Simple read-only block device emulation access to MTD devices");