linux/drivers/mtd/mtdblock_ro.c
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   1/*
   2 * Simple read-only (writable only for RAM) mtdblock driver
   3 *
   4 * Copyright © 2001-2010 David Woodhouse <dwmw2@infradead.org>
   5 *
   6 * This program is free software; you can redistribute it and/or modify
   7 * it under the terms of the GNU General Public License as published by
   8 * the Free Software Foundation; either version 2 of the License, or
   9 * (at your option) any later version.
  10 *
  11 * This program is distributed in the hope that it will be useful,
  12 * but WITHOUT ANY WARRANTY; without even the implied warranty of
  13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14 * GNU General Public License for more details.
  15 *
  16 * You should have received a copy of the GNU General Public License
  17 * along with this program; if not, write to the Free Software
  18 * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
  19 *
  20 */
  21
  22#include <linux/init.h>
  23#include <linux/slab.h>
  24#include <linux/mtd/mtd.h>
  25#include <linux/mtd/blktrans.h>
  26#include <linux/module.h>
  27
  28static int mtdblock_readsect(struct mtd_blktrans_dev *dev,
  29                              unsigned long block, char *buf)
  30{
  31        size_t retlen;
  32
  33        if (mtd_read(dev->mtd, (block * 512), 512, &retlen, buf))
  34                return 1;
  35        return 0;
  36}
  37
  38static int mtdblock_writesect(struct mtd_blktrans_dev *dev,
  39                              unsigned long block, char *buf)
  40{
  41        size_t retlen;
  42
  43        if (mtd_write(dev->mtd, (block * 512), 512, &retlen, buf))
  44                return 1;
  45        return 0;
  46}
  47
  48static void mtdblock_add_mtd(struct mtd_blktrans_ops *tr, struct mtd_info *mtd)
  49{
  50        struct mtd_blktrans_dev *dev = kzalloc(sizeof(*dev), GFP_KERNEL);
  51
  52        if (!dev)
  53                return;
  54
  55        dev->mtd = mtd;
  56        dev->devnum = mtd->index;
  57
  58        dev->size = mtd->size >> 9;
  59        dev->tr = tr;
  60        dev->readonly = 1;
  61
  62        if (add_mtd_blktrans_dev(dev))
  63                kfree(dev);
  64}
  65
  66static void mtdblock_remove_dev(struct mtd_blktrans_dev *dev)
  67{
  68        del_mtd_blktrans_dev(dev);
  69}
  70
  71static struct mtd_blktrans_ops mtdblock_tr = {
  72        .name           = "mtdblock",
  73        .major          = 31,
  74        .part_bits      = 0,
  75        .blksize        = 512,
  76        .readsect       = mtdblock_readsect,
  77        .writesect      = mtdblock_writesect,
  78        .add_mtd        = mtdblock_add_mtd,
  79        .remove_dev     = mtdblock_remove_dev,
  80        .owner          = THIS_MODULE,
  81};
  82
  83static int __init mtdblock_init(void)
  84{
  85        return register_mtd_blktrans(&mtdblock_tr);
  86}
  87
  88static void __exit mtdblock_exit(void)
  89{
  90        deregister_mtd_blktrans(&mtdblock_tr);
  91}
  92
  93module_init(mtdblock_init);
  94module_exit(mtdblock_exit);
  95
  96MODULE_LICENSE("GPL");
  97MODULE_AUTHOR("David Woodhouse <dwmw2@infradead.org>");
  98MODULE_DESCRIPTION("Simple read-only block device emulation access to MTD devices");
  99
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