// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * Simple read-only (writable only for RAM) mtdblock driver
 *
 * Copyright © 2001-2010 David Woodhouse <dwmw2@infradead.org>
 */

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

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

        err = mtd_read(dev->mtd, (block * 512), 512, &retlen, buf);
        if (err && !mtd_is_bitflip(err))
                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_obj(*dev);

        if (!dev)
                return;

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

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

        if (mtd_type_is_nand(mtd))
                pr_warn_ratelimited("%s: MTD device '%s' is NAND, please consider using UBI block devices instead.\n",
                        tr->name, mtd->name);

        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          = MTD_BLOCK_MAJOR,
        .part_bits      = 0,
        .blksize        = 512,
        .readsect       = mtdblock_readsect,
        .writesect      = mtdblock_writesect,
        .add_mtd        = mtdblock_add_mtd,
        .remove_dev     = mtdblock_remove_dev,
        .owner          = THIS_MODULE,
};

module_mtd_blktrans(mtdblock_tr);

MODULE_LICENSE("GPL");
MODULE_AUTHOR("David Woodhouse <dwmw2@infradead.org>");
MODULE_DESCRIPTION("Simple read-only block device emulation access to MTD devices");