path: root/drivers/mtd/mtdchar.c

/*
 * Copyright © 1999-2010 David Woodhouse <dwmw2@infradead.org>
 *
 * 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/device.h>
#include <linux/fs.h>
#include <linux/mm.h>
#include <linux/err.h>
#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/slab.h>
#include <linux/sched.h>
#include <linux/mutex.h>
#include <linux/backing-dev.h>
#include <linux/compat.h>
#include <linux/mount.h>
#include <linux/blkpg.h>
#include <linux/magic.h>
#include <linux/major.h>
#include <linux/mtd/mtd.h>
#include <linux/mtd/partitions.h>
#include <linux/mtd/map.h>

#include <asm/uaccess.h>

#include "mtdcore.h"

static DEFINE_MUTEX(mtd_mutex);

/*
 * Data structure to hold the pointer to the mtd device as well
 * as mode information of various use cases.
 */
struct mtd_file_info {
	struct mtd_info *mtd;
	enum mtd_file_modes mode;
};

static loff_t mtdchar_lseek(struct file *file, loff_t offset, int orig)
{
	struct mtd_file_info *mfi = file->private_data;
	return fixed_size_llseek(file, offset, orig, mfi->mtd->size);
}

static int mtdchar_open(struct inode *inode, struct file *file)
{
	int minor = iminor(inode);
	int devnum = minor >> 1;
	int ret = 0;
	struct mtd_info *mtd;
	struct mtd_file_info *mfi;

	pr_debug("MTD_open\n");

	/* You can't open the RO devices RW */
	if ((file->f_mode & FMODE_WRITE) && (minor & 1))
		return -EACCES;

	mutex_lock(&mtd_mutex);
	mtd = get_mtd_device(NULL, devnum);

	if (IS_ERR(mtd)) {
		ret = PTR_ERR(mtd);
		goto out;
	}

	if (mtd->type == MTD_ABSENT) {
		ret = -ENODEV;
		goto out1;
	}

	/* You can't open it RW if it's not a writeable device */
	if ((file->f_mode & FMODE_WRITE) && !(mtd->flags & MTD_WRITEABLE)) {
		ret = -EACCES;
		goto out1;
	}

	mfi = kzalloc(sizeof(*mfi), GFP_KERNEL);
	if (!mfi) {
		ret = -ENOMEM;
		goto out1;
	}
	mfi->mtd = mtd;
	file->private_data = mfi;
	mutex_unlock(&mtd_mutex);
	return 0;

out1:
	put_mtd_device(mtd);
out:
	mutex_unlock(&mtd_mutex);
	return ret;
} /* mtdchar_open */

/*====================================================================*/

static int mtdchar_close(struct inode *inode, struct file *file)
{
	struct mtd_file_info *mfi = file->private_data;
	struct mtd_info *mtd = mfi->mtd;

	pr_debug("MTD_close\n");

	/* Only sync if opened RW */
	if ((file->f_mode & FMODE_WRITE))
		mtd_sync(mtd);

	put_mtd_device(mtd);
	file->private_data = NULL;
	kfree(mfi);

	return 0;
} /* mtdchar_close */

/* Back in June 2001, dwmw2 wrote:
 *
 *   FIXME: This _really_ needs to die. In 2.5, we should lock the
 *   userspace buffer down and use it directly with readv/writev.
 *
 * The implementation below, using mtd_kmalloc_up_to, mitigates
 * allocation failures when the system is under low-memory situations
 * or if memory is highly fragmented at the cost of reducing the
 * performance of the requested transfer due to a smaller buffer size.
 *
 * A more complex but more memory-efficient implementation based on
 * get_user_pages and iovecs to cover extents of those pages is a
 * longer-term goal, as intimated by dwmw2 above. However, for the
 * write case, this requires yet more complex head and tail transfer
 * handling when those head and tail offsets and sizes are such that
 * alignment requirements are not met in the NAND subdriver.
 */

static ssize_t mtdchar_read(struct file *file, char __user *buf, size_t count,
			loff_t *ppos)
{
	struct mtd_file_info *mfi = file->private_data;
	struct mtd_info *mtd = mfi->mtd;
	size_t retlen;
	size_t total_retlen=0;
	int ret=0;
	int len;
	size_t size = count;
	char *kbuf;