drivers/mtd/mtdblock_ro.c

   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
  27 static int mtdblock_readsect(struct mtd_blktrans_dev *dev,
  28                               unsigned long block, char *buf)
  29 {
  30         size_t retlen;
  31
  32         if (dev->mtd->read(dev->mtd, (block * 512), 512, &retlen, buf))
  33                 return 1;
  34         return 0;
  35 }
  36
  37 static int mtdblock_writesect(struct mtd_blktrans_dev *dev,
  38                               unsigned long block, char *buf)
  39 {
  40         size_t retlen;
  41
  42         if (dev->mtd->write(dev->mtd, (block * 512), 512, &retlen, buf))
  43                 return 1;
  44         return 0;
  45 }
  46
  47 static void mtdblock_add_mtd(struct mtd_blktrans_ops *tr, struct mtd_info *mtd)
  48 {
  49         struct mtd_blktrans_dev *dev = kzalloc(sizeof(*dev), GFP_KERNEL);
  50
  51         if (!dev)
  52                 return;
  53
  54         dev->mtd = mtd;
  55         dev->devnum = mtd->index;
  56
  57         dev->size = mtd->size >> 9;
  58         dev->tr = tr;
  59         dev->readonly = 1;
  60
  61         if (add_mtd_blktrans_dev(dev))
  62                 kfree(dev);
  63 }
  64
  65 static void mtdblock_remove_dev(struct mtd_blktrans_dev *dev)
  66 {
  67         del_mtd_blktrans_dev(dev);
  68 }
  69
  70 static struct mtd_blktrans_ops mtdblock_tr = {
  71         .name           = "mtdblock",
  72         .major          = 31,
  73         .part_bits      = 0,
  74         .blksize        = 512,
  75         .readsect       = mtdblock_readsect,
  76         .writesect      = mtdblock_writesect,
  77         .add_mtd        = mtdblock_add_mtd,
  78         .remove_dev     = mtdblock_remove_dev,
  79         .owner          = THIS_MODULE,
  80 };
  81
  82 static int __init mtdblock_init(void)
  83 {
  84         return register_mtd_blktrans(&mtdblock_tr);
  85 }
  86
  87 static void __exit mtdblock_exit(void)
  88 {
  89         deregister_mtd_blktrans(&mtdblock_tr);
  90 }
  91
  92 module_init(mtdblock_init);
  93 module_exit(mtdblock_exit);
  94
  95 MODULE_LICENSE("GPL");
  96 MODULE_AUTHOR("David Woodhouse <dwmw2@infradead.org>");
  97 MODULE_DESCRIPTION("Simple read-only block device emulation access to MTD devices");