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