/*
* MTD device concatenation layer
*
* Copyright © 2002 Robert Kaiser <rkaiser@sysgo.de>
* Copyright © 2002-2010 David Woodhouse <dwmw2@infradead.org>
*
* NAND support by Christian Gan <cgan@iders.ca>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
*
*/
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/slab.h>
#include <linux/sched.h>
#include <linux/types.h>
#include <linux/backing-dev.h>
#include <linux/mtd/mtd.h>
#include <linux/mtd/concat.h>
#include <asm/div64.h>
/*
* Our storage structure:
* Subdev points to an array of pointers to struct mtd_info objects
* which is allocated along with this structure
*
*/
struct mtd_concat {
struct mtd_info mtd;
int num_subdev;
struct mtd_info **subdev;
};
/*
* how to calculate the size required for the above structure,
* including the pointer array subdev points to:
*/
#define SIZEOF_STRUCT_MTD_CONCAT(num_subdev) \
((sizeof(struct mtd_concat) + (num_subdev) * sizeof(struct mtd_info *)))
/*
* Given a pointer to the MTD object in the mtd_concat structure,
* we can retrieve the pointer to that structure with this macro.
*/
#define CONCAT(x) ((struct mtd_concat *)(x))
/*
* MTD methods which look up the relevant subdevice, translate the
* effective address and pass through to the subdevice.
*/
static int
concat_read(struct mtd_info *mtd, loff_t from, size_t len,
size_t * retlen, u_char * buf)
{
struct mtd_concat *concat = CONCAT(mtd);
int ret = 0, err;
int i;
*retlen = 0;
for (i = 0; i < concat->num_subdev; i++) {
struct mtd_info *subdev = concat->subdev[i];
size_t size, retsize;
if (from >= subdev->size) {
/* Not destined for this subdev */
size = 0;
from -= subdev->size;
continue;
}
if (from + len > subdev->size)
/* First part goes into this subdev */
size = subdev->size - from;
else
/* Entire transaction goes into this subdev */
size = len;
err = mtd_read(subdev, from, size, &retsize, buf);
/* Save information about bitflips! */
if (unlikely(err)) {
if (mtd_is_eccerr(err)) {
mtd->ecc_stats.failed++;
ret = err;
} else if (mtd_is_bitflip(err)) {
mtd->ecc_stats.corrected++;
/* Do not overwrite -EBADMSG !! */
if (!ret)
ret = err;
} else
return err;
}
*retlen += retsize;
len -= size;
if (len == 0)
return ret;
buf += size;
from = 0;
}
return -EINVAL;
}
static int
concat_write(struct mtd_info *mtd, loff_t to, size_t len,
size_t * retlen, const u_char * buf)
{
struct mtd_concat *concat = CONCAT(mtd);
int err = -EINVAL;
int i;
if (!(mtd->flags & MTD_WRITEABLE))
return -EROFS;
*retlen = 0;
for (i = 0; i < concat->num_subdev; i++) {
struct mtd_info *subdev = concat->subdev[i];
size_t size, retsize;
if (to >= subdev->size) {
size = 0;
to -= subdev->size;
continue;
}
if (to + len > subdev->size)
size = subdev->size - to;
else
size = len;
if (!(subdev->flags & MTD_WRITEABLE))
err = -EROFS;
else
err = mtd_write(subdev, to, size, &retsize, buf);
if (err)
break;
*retlen += retsize;
len -= size;
if (len == 0)
break;
err = -EINVAL;
buf += size;
to = 0;
}
return err;
}
static