path: root/drivers/mtd/mtdconcat.c

/*
 * 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;

	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;

	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;

		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 int
concat_writev(struct mtd_info *mtd, const struct kvec *vecs,
		unsigned long count, loff_t to, size_t * retlen)
{
	struct mtd_concat *concat = CONCAT(mtd);
	struct kvec *vecs_copy;
	unsigned long entry_low, entry_high;
	size_t total_len = 0;
	int i;
	int err = -EINVAL;

	/* Calculate total length of data */
	for (i = 0; i < count; i++)
		total_len += vecs[i].iov_len;

	/* Check alignment */
	if (mtd->writesize > 1) {
		uint64_t __to = to;
		if (do_div