1// SPDX-License-Identifier: GPL-2.0-or-later
2/*
3 * Simple read-only (writable only for RAM) mtdblock driver
4 *
5 * Copyright © 2001-2010 David Woodhouse <dwmw2@infradead.org>
6 */
7
8#include <linux/init.h>
9#include <linux/slab.h>
10#include <linux/mtd/mtd.h>
11#include <linux/mtd/blktrans.h>
12#include <linux/module.h>
13#include <linux/major.h>
14
15static int mtdblock_readsect(struct mtd_blktrans_dev *dev,
16			      unsigned long block, char *buf)
17{
18	size_t retlen;
19
20	if (mtd_read(dev->mtd, (block * 512), 512, &retlen, buf))
21		return 1;
22	return 0;
23}
24
25static int mtdblock_writesect(struct mtd_blktrans_dev *dev,
26			      unsigned long block, char *buf)
27{
28	size_t retlen;
29
30	if (mtd_write(dev->mtd, (block * 512), 512, &retlen, buf))
31		return 1;
32	return 0;
33}
34
35static void mtdblock_add_mtd(struct mtd_blktrans_ops *tr, struct mtd_info *mtd)
36{
37	struct mtd_blktrans_dev *dev = kzalloc(sizeof(*dev), GFP_KERNEL);
38
39	if (!dev)
40		return;
41
42	dev->mtd = mtd;
43	dev->devnum = mtd->index;
44
45	dev->size = mtd->size >> 9;
46	dev->tr = tr;
47	dev->readonly = 1;
48
49	if (add_mtd_blktrans_dev(dev))
50		kfree(dev);
51}
52
53static void mtdblock_remove_dev(struct mtd_blktrans_dev *dev)
54{
55	del_mtd_blktrans_dev(dev);
56}
57
58static struct mtd_blktrans_ops mtdblock_tr = {
59	.name		= "mtdblock",
60	.major		= MTD_BLOCK_MAJOR,
61	.part_bits	= 0,
62	.blksize 	= 512,
63	.readsect	= mtdblock_readsect,
64	.writesect	= mtdblock_writesect,
65	.add_mtd	= mtdblock_add_mtd,
66	.remove_dev	= mtdblock_remove_dev,
67	.owner		= THIS_MODULE,
68};
69
70static int __init mtdblock_init(void)
71{
72	return register_mtd_blktrans(&mtdblock_tr);
73}
74
75static void __exit mtdblock_exit(void)
76{
77	deregister_mtd_blktrans(&mtdblock_tr);
78}
79
80module_init(mtdblock_init);
81module_exit(mtdblock_exit);
82
83MODULE_LICENSE("GPL");
84MODULE_AUTHOR("David Woodhouse <dwmw2@infradead.org>");
85MODULE_DESCRIPTION("Simple read-only block device emulation access to MTD devices");
86