text: /*
   * 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/smp_lock.h>
  #include <linux/backing-dev.h>
  #include <linux/compat.h>
  #include <linux/mount.h>
  
  #include <linux/mtd/mtd.h>
  #include <linux/mtd/map.h>
  
  #include <asm/uaccess.h>
  
  #define MTD_INODE_FS_MAGIC 0x11307854
  static struct vfsmount *mtd_inode_mnt __read_mostly;
  
  /*
   * Data structure to hold the pointer to the mtd device as well
   * as mode information ofr various use cases.
   */
  struct mtd_file_info {
  	struct mtd_info *mtd;
  	struct inode *ino;
  	enum mtd_file_modes mode;
  };
  
  static loff_t mtd_lseek (struct file *file, loff_t offset, int orig)
  {
  	struct mtd_file_info *mfi = file->private_data;
  	struct mtd_info *mtd = mfi->mtd;
  
  	switch (orig) {
  	case SEEK_SET:
  		break;
  	case SEEK_CUR:
  		offset += file->f_pos;
  		break;
  	case SEEK_END:
  		offset += mtd->size;
  		break;
  	default:
  		return -EINVAL;
  	}
  
  	if (offset >= 0 && offset <= mtd->size)
  		return file->f_pos = offset;
  
  	return -EINVAL;
  }
  
  
  
  static int mtd_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;
  	struct inode *mtd_ino;
  
  	DEBUG(MTD_DEBUG_LEVEL0, "MTD_open\n");
  
  	/* You can't open the RO devices RW */
  	if ((file->f_mode & FMODE_WRITE) && (minor & 1))
  		return -EACCES;
  
  	lock_kernel();
  	mtd = get_mtd_device(NULL, devnum);
  
  	if (IS_ERR(mtd)) {
  		ret = PTR_ERR(mtd);
  		goto out;
  	}
  
  	if (mtd->type == MTD_ABSENT) {
  		put_mtd_device(mtd);
  		ret = -ENODEV;
  		goto out;
  	}
  
  	mtd_ino = iget_locked(mtd_inode_mnt->mnt_sb, devnum);
  	if (!mtd_ino) {
  		put_mtd_device(mtd);
  		ret = -ENOMEM;
  		goto out;
  	}
  	if (mtd_ino->i_state & I_NEW) {
  		mtd_ino->i_private = mtd;
  		mtd_ino->i_mode = S_IFCHR;
  		mtd_ino->i_data.backing_dev_info = mtd->backing_dev_info;
  		unlock_new_inode(mtd_ino);
  	}
  	file->f_mapping = mtd_ino->i_mapping;
  
  	/* You can't open it RW if it's not a writeable device */
  	if ((file->f_mode & FMODE_WRITE) && !(mtd->flags & MTD_WRITEABLE)) {
  		iput(mtd_ino);
  		put_mtd_device(mtd);
  		ret = -EACCES;
  		goto out;
  	}
  
  	mfi = kzalloc(sizeof(*mfi), GFP_KERNEL);
  	if (!mfi) {
  		iput(mtd_ino);
  		put_mtd_device(mtd);
  		ret = -ENOMEM;
  		goto out;
  	}
  	mfi->ino = mtd_ino;
  	mfi->mtd = mtd;
  	file->private_data = mfi;
  
  out:
  	unlock_kernel();
  	return ret;
  } /* mtd_open */
  
  /*====================================================================*/
  
  static int mtd_close(struct inode *inode, struct file *file)
  {
  	struct mtd_file_info *mfi = file->private_data;
  	struct mtd_info *mtd = mfi->mtd;
  
  	DEBUG(MTD_DEBUG_LEVEL0, "MTD_close\n");
  
  	/* Only sync if opened RW */
  	if ((file->f_mode & FMODE_WRITE) && mtd->sync)
  		mtd->sync(mtd);
  
  	iput(mfi->ino);
  
  	put_mtd_device(mtd);
  	file->private_data = NULL;
  	kfree(mfi);
  
  	return 0;
  } /* mtd_close */
  
  /* FIXME: This _really_ needs to die. In 2.5, we should lock the
     userspace buffer down and use it directly with readv/writev.
  */
  #define MAX_KMALLOC_SIZE 0x20000
  
  static ssize_t mtd_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=0;
  	size_t total_retlen=0;
  	int ret=0;
  	int len;
  	char *kbuf;
  
  	DEBUG(MTD_DEBUG_LEVEL0,"MTD_read\n");
  
  	if (*ppos + count > mtd->size)
  		count = mtd->size - *ppos;
  
  	if (!count)
  		return 0;
  
  	/* FIXME: Use kiovec in 2.5 to lock down the user's buffers
  	   and pass them directly to the MTD functions */
  
  	if (count > MAX_KMALLOC_SIZE)
  		kbuf=kmalloc(MAX_KMALLOC_SIZE, GFP_KERNEL);
  	else
  		kbuf=kmalloc(count, GFP_KERNEL);
  
  	if (!kbuf)
  		return -ENOMEM;
  
  	while (count) {
  
  		if (count > MAX_KMALLOC_SIZE)
  			len = MAX_KMALLOC_SIZE;
  		else
  			len = count;
  
  		switch (mfi->mode) {
  		case MTD_MODE_OTP_FACTORY:
  			ret = mtd->read_fact_prot_reg(mtd, *ppos, len, &retlen, kbuf);
  			break;
  		case MTD_MODE_OTP_USER:
  			ret = mtd->read_user_prot_reg(mtd, *ppos, len, &retlen, kbuf);
  			break;
  		case MTD_MODE_RAW:
  		{
  			struct mtd_oob_ops ops;
  
  			ops.mode = MTD_OOB_RAW;
  			ops.datbuf = kbuf;
  			ops.oobbuf = NULL;
  			ops.len = len;
  
  			ret = mtd->read_oob(mtd, *ppos, &ops);
  			retlen = ops.retlen;
  			break;
  		}
  		default:
  			ret = mtd->read(mtd, *ppos, len, &retlen, kbuf);
  		}
  		/* Nand returns -EBADMSG on ecc errors, but it returns
  		 * the data. For our userspace tools it is important
  		 * to dump areas with ecc errors !
  		 * For kernel internal usage it also might return -EUCLEAN
  		 * to signal the caller that a bitflip has occured and has
  		 * been corrected by the ECC algorithm.
  		 * Userspace software which accesses NAND this way
  		 * must be aware of the fact that it deals with NAND
  		 */
  		if (!ret || (ret == -EUCLEAN) || (ret == -EBADMSG)) {
  			*ppos += retlen;
  			if (copy_to_user(buf, kbuf, retlen)) {
  				kfree(kbuf);
  				return -EFAULT;
  			}
  			else
  				total_retlen += retlen;
  
  			count -= retlen;
  			buf += retlen;
  			if (retlen == 0)
  				count = 0;
  		}
  		else {
  			kfree(kbuf);
  			return ret;
  		}
  
  	}
  
  	kfree(kbuf);
  	return total_retlen;
  } /* mtd_read */
  
  static ssize_t mtd_write(struct file *file, const char __user *buf, size_t count,loff_t *ppos)
  {
  	struct mtd_file_info *mfi = file->private_data;
  	struct mtd_info *mtd = mfi->mtd;
  	char *kbuf;
  	size_t retlen;
  	size_t total_retlen=0;
  	int ret=0;
  	int len;
  
  	DEBUG(MTD_DEBUG_LEVEL0,"MTD_write\n");
  
  	if (*ppos == mtd->size)
  		return -ENOSPC;
  
  	if (*ppos + count > mtd->size)
  		count = mtd->size - *ppos;
  
  	if (!count)
  		return 0;
  
  	if (count > MAX_KMALLOC_SIZE)
  		kbuf=kmalloc(MAX_KMALLOC_SIZE, GFP_KERNEL);
  	else
  		kbuf=kmalloc(count, GFP_KERNEL);
  
  	if (!kbuf)
  		return -ENOMEM;
  
  	while (count) {
  
  		if (count > MAX_KMALLOC_SIZE)
  			len = MAX_KMALLOC_SIZE;
  		else
  			len = count;
  
  		if (copy_from_user(kbuf, buf, len)) {
  			kfree(kbuf);
  			return -EFAULT;
  		}
  
  		switch (mfi->mode) {
  		case MTD_MODE_OTP_FACTORY:
  			ret = -EROFS;
  			break;
  		case MTD_MODE_OTP_USER:
  			if (!mtd->write_user_prot_reg) {
  				ret = -EOPNOTSUPP;
  				break;
  			}
  			ret = mtd->write_user_prot_reg(mtd, *ppos, len, &retlen, kbuf);
  			break;
  
  		case MTD_MODE_RAW:
  		{
  			struct mtd_oob_ops ops;
  
  			ops.mode = MTD_OOB_RAW;
  			ops.datbuf = kbuf;
  			ops.oobbuf = NULL;
  			ops.len = len;
  
  			ret = mtd->write_oob(mtd, *ppos, &ops);
  			retlen = ops.retlen;
  			break;
  		}
  
  		default:
  			ret = (*(mtd->write))(mtd, *ppos, len, &retlen, kbuf);
  		}
  		if (!ret) {
  			*ppos += retlen;
  			total_retlen += retlen;
  			count -= retlen;
  			buf += retlen;
  		}
  		else {
  			kfree(kbuf);
  			return ret;
  		}
  	}
  
  	kfree(kbuf);
  	return total_retlen;
  } /* mtd_write */
  
  /*======================================================================
  
      IOCTL calls for getting device parameters.
  
  ======================================================================*/
  static void mtdchar_erase_callback (struct erase_info *instr)
  {
  	wake_up((wait_queue_head_t *)instr->priv);
  }
  
  #ifdef CONFIG_HAVE_MTD_OTP
  static int otp_select_filemode(struct mtd_file_info *mfi, int mode)
  {
  	struct mtd_info *mtd = mfi->mtd;
  	int ret = 0;
  
  	switch (mode) {
  	case MTD_OTP_FACTORY:
  		if (!mtd->read_fact_prot_reg)
  			ret = -EOPNOTSUPP;
  		else
  			mfi->mode = MTD_MODE_OTP_FACTORY;
  		break;
  	case MTD_OTP_USER:
  		if (!mtd->read_fact_prot_reg)
  			ret = -EOPNOTSUPP;
  		else
  			mfi->mode = MTD_MODE_OTP_USER;
  		break;
  	default:
  		ret = -EINVAL;
  	case MTD_OTP_OFF:
  		break;
  	}
  	return ret;
  }
  #else
  # define otp_select_filemode(f,m)	-EOPNOTSUPP
  #endif
  
  static int mtd_do_writeoob(struct file *file, struct mtd_info *mtd,
  	uint64_t start, uint32_t length, void __user *ptr,
  	uint32_t __user *retp)
  {
  	struct mtd_oob_ops ops;
  	uint32_t retlen;
  	int ret = 0;
  
  	if (!(file->f_mode & FMODE_WRITE))
  		return -EPERM;
  
  	if (length > 4096)
  		return -EINVAL;
  
  	if (!mtd->write_oob)
  		ret = -EOPNOTSUPP;
  	else
  		ret = access_ok(VERIFY_READ, ptr, length) ? 0 : -EFAULT;
  
  	if (ret)
  		return ret;
  
  	ops.ooblen = length;
  	ops.ooboffs = start & (mtd->oobsize - 1);
  	ops.datbuf = NULL;
  	ops.mode = MTD_OOB_PLACE;
  
  	if (ops.ooboffs && ops.ooblen > (mtd->oobsize - ops.ooboffs))
  		return -EINVAL;
  
  	ops.oobbuf = memdup_user(ptr, length);
  	if (IS_ERR(ops.oobbuf))
  		return PTR_ERR(ops.oobbuf);
  
  	start &= ~((uint64_t)mtd->oobsize - 1);
  	ret = mtd->write_oob(mtd, start, &ops);
  
  	if (ops.oobretlen > 0xFFFFFFFFU)
  		ret = -EOVERFLOW;
  	retlen = ops.oobretlen;
  	if (copy_to_user(retp, &retlen, sizeof(length)))
  		ret = -EFAULT;
  
  	kfree(ops.oobbuf);
  	return ret;
  }
  
  static int mtd_do_readoob(struct mtd_info *mtd, uint64_t start,
  	uint32_t length, void __user *ptr, uint32_t __user *retp)
  {
  	struct mtd_oob_ops ops;
  	int ret = 0;
  
  	if (length > 4096)
  		return -EINVAL;
  
  	if (!mtd->read_oob)
  		ret = -EOPNOTSUPP;
  	else
  		ret = access_ok(VERIFY_WRITE, ptr,
  				length) ? 0 : -EFAULT;
  	if (ret)
  		return ret;
  
  	ops.ooblen = length;
  	ops.ooboffs = start & (mtd->oobsize - 1);
  	ops.datbuf = NULL;
  	ops.mode = MTD_OOB_PLACE;
  
  	if (ops.ooboffs && ops.ooblen > (mtd->oobsize - ops.ooboffs))
  		return -EINVAL;
  
  	ops.oobbuf = kmalloc(length, GFP_KERNEL);
  	if (!ops.oobbuf)
  		return -ENOMEM;
  
  	start &= ~((uint64_t)mtd->oobsize - 1);
  	ret = mtd->read_oob(mtd, start, &ops);
  
  	if (put_user(ops.oobretlen, retp))
  		ret = -EFAULT;
  	else if (ops.oobretlen && copy_to_user(ptr, ops.oobbuf,
  					    ops.oobretlen))
  		ret = -EFAULT;
  
  	kfree(ops.oobbuf);
  	return ret;
  }
  
  static int mtd_ioctl(struct file *file, u_int cmd, u_long arg)
  {
  	struct mtd_file_info *mfi = file->private_data;
  	struct mtd_info *mtd = mfi->mtd;
  	void __user *argp = (void __user *)arg;
  	int ret = 0;
  	u_long size;
  	struct mtd_info_user info;
  
  	DEBUG(MTD_DEBUG_LEVEL0, "MTD_ioctl\n");
  
  	size = (cmd & IOCSIZE_MASK) >> IOCSIZE_SHIFT;
  	if (cmd & IOC_IN) {
  		if (!access_ok(VERIFY_READ, argp, size))
  			return -EFAULT;
  	}
  	if (cmd & IOC_OUT) {
  		if (!access_ok(VERIFY_WRITE, argp, size))
  			return -EFAULT;
  	}
  
  	switch (cmd) {
  	case MEMGETREGIONCOUNT:
  		if (copy_to_user(argp, &(mtd->numeraseregions), sizeof(int)))
  			return -EFAULT;
  		break;
  
  	case MEMGETREGIONINFO:
  	{
  		uint32_t ur_idx;
  		struct mtd_erase_region_info *kr;
  		struct region_info_user __user *ur = argp;
  
  		if (get_user(ur_idx, &(ur->regionindex)))
  			return -EFAULT;
  
  		kr = &(mtd->eraseregions[ur_idx]);
  
  		if (put_user(kr->offset, &(ur->offset))
  		    || put_user(kr->erasesize, &(ur->erasesize))
  		    || put_user(kr->numblocks, &(ur->numblocks)))
  			return -EFAULT;
  
  		break;
  	}
  
  	case MEMGETINFO:
  		info.type	= mtd->type;
  		info.flags	= mtd->flags;
  		info.size	= mtd->size;
  		info.erasesize	= mtd->erasesize;
  		info.writesize	= mtd->writesize;
  		info.oobsize	= mtd->oobsize;
  		/* The below fields are obsolete */
  		info.ecctype	= -1;
  		info.eccsize	= 0;
  		if (copy_to_user(argp, &info, sizeof(struct mtd_info_user)))
  			return -EFAULT;
  		break;
  
  	case MEMERASE:
  	case MEMERASE64:
  	{
  		struct erase_info *erase;
  
  		if(!(file->f_mode & FMODE_WRITE))
  			return -EPERM;
  
  		erase=kzalloc(sizeof(struct erase_info),GFP_KERNEL);
  		if (!erase)
  			ret = -ENOMEM;
  		else {
  			wait_queue_head_t waitq;
  			DECLARE_WAITQUEUE(wait, current);
  
  			init_waitqueue_head(&waitq);
  
  			if (cmd == MEMERASE64) {
  				struct erase_info_user64 einfo64;
  
  				if (copy_from_user(&einfo64, argp,
  					    sizeof(struct erase_info_user64))) {
  					kfree(erase);
  					return -EFAULT;
  				}
  				erase->addr = einfo64.start;
  				erase->len = einfo64.length;
  			} else {
  				struct erase_info_user einfo32;
  
  				if (copy_from_user(&einfo32, argp,
  					    sizeof(struct erase_info_user))) {
  					kfree(erase);
  					return -EFAULT;
  				}
  				erase->addr = einfo32.start;
  				erase->len = einfo32.length;
  			}
  			erase->mtd = mtd;
  			erase->callback = mtdchar_erase_callback;
  			erase->priv = (unsigned long)&waitq;
  
  			/*
  			  FIXME: Allow INTERRUPTIBLE. Which means
  			  not having the wait_queue head on the stack.
  
  			  If the wq_head is on the stack, and we
  			  leave because we got interrupted, then the
  			  wq_head is no longer there when the
  			  callback routine tries to wake us up.
  			*/
  			ret = mtd->erase(mtd, erase);
  			if (!ret) {
  				set_current_state(TASK_UNINTERRUPTIBLE);
  				add_wait_queue(&waitq, &wait);
  				if (erase->state != MTD_ERASE_DONE &&
  				    erase->state != MTD_ERASE_FAILED)
  					schedule();
  				remove_wait_queue(&waitq, &wait);
  				set_current_state(TASK_RUNNING);
  
  				ret = (erase->state == MTD_ERASE_FAILED)?-EIO:0;
  			}
  			kfree(erase);
  		}
  		break;
  	}
  
  	case MEMWRITEOOB:
  	{
  		struct mtd_oob_buf buf;
  		struct mtd_oob_buf __user *buf_user = argp;
  
  		/* NOTE: writes return length to buf_user->length */
  		if (copy_from_user(&buf, argp, sizeof(buf)))
  			ret = -EFAULT;
  		else
  			ret = mtd_do_writeoob(file, mtd, buf.start, buf.length,
  				buf.ptr, &buf_user->length);
  		break;
  	}
  
  	case MEMREADOOB:
  	{
  		struct mtd_oob_buf buf;
  		struct mtd_oob_buf __user *buf_user = argp;
  
  		/* NOTE: writes return length to buf_user->start */
  		if (copy_from_user(&buf, argp, sizeof(buf)))
  			ret = -EFAULT;
  		else
  			ret = mtd_do_readoob(mtd, buf.start, buf.length,
  				buf.ptr, &buf_user->start);
  		break;
  	}
  
  	case MEMWRITEOOB64:
  	{
  		struct mtd_oob_buf64 buf;
  		struct mtd_oob_buf64 __user *buf_user = argp;
  
  		if (copy_from_user(&buf, argp, sizeof(buf)))
  			ret = -EFAULT;
  		else
  			ret = mtd_do_writeoob(file, mtd, buf.start, buf.length,
  				(void __user *)(uintptr_t)buf.usr_ptr,
  				&buf_user->length);
  		break;
  	}
  
  	case MEMREADOOB64:
  	{
  		struct mtd_oob_buf64 buf;
  		struct mtd_oob_buf64 __user *buf_user = argp;
  
  		if (copy_from_user(&buf, argp, sizeof(buf)))
  			ret = -EFAULT;
  		else
  			ret = mtd_do_readoob(mtd, buf.start, buf.length,
  				(void __user *)(uintptr_t)buf.usr_ptr,
  				&buf_user->length);
  		break;
  	}
  
  	case MEMLOCK:
  	{
  		struct erase_info_user einfo;
  
  		if (copy_from_user(&einfo, argp, sizeof(einfo)))
  			return -EFAULT;
  
  		if (!mtd->lock)
  			ret = -EOPNOTSUPP;
  		else
  			ret = mtd->lock(mtd, einfo.start, einfo.length);
  		break;
  	}
  
  	case MEMUNLOCK:
  	{
  		struct erase_info_user einfo;
  
  		if (copy_from_user(&einfo, argp, sizeof(einfo)))
  			return -EFAULT;
  
  		if (!mtd->unlock)
  			ret = -EOPNOTSUPP;
  		else
  			ret = mtd->unlock(mtd, einfo.start, einfo.length);
  		break;
  	}
  
  	case MEMISLOCKED:
  	{
  		struct erase_info_user einfo;
  
  		if (copy_from_user(&einfo, argp, sizeof(einfo)))
  			return -EFAULT;
  
  		if (!mtd->is_locked)
  			ret = -EOPNOTSUPP;
  		else
  			ret = mtd->is_locked(mtd, einfo.start, einfo.length);
  		break;
  	}
  
  	/* Legacy interface */
  	case MEMGETOOBSEL:
  	{
  		struct nand_oobinfo oi;
  
  		if (!mtd->ecclayout)
  			return -EOPNOTSUPP;
  		if (mtd->ecclayout->eccbytes > ARRAY_SIZE(oi.eccpos))
  			return -EINVAL;
  
  		oi.useecc = MTD_NANDECC_AUTOPLACE;
  		memcpy(&oi.eccpos, mtd->ecclayout->eccpos, sizeof(oi.eccpos));
  		memcpy(&oi.oobfree, mtd->ecclayout->oobfree,
  		       sizeof(oi.oobfree));
  		oi.eccbytes = mtd->ecclayout->eccbytes;
  
  		if (copy_to_user(argp, &oi, sizeof(struct nand_oobinfo)))
  			return -EFAULT;
  		break;
  	}
  
  	case MEMGETBADBLOCK:
  	{
  		loff_t offs;
  
  		if (copy_from_user(&offs, argp, sizeof(loff_t)))
  			return -EFAULT;
  		if (!mtd->block_isbad)
  			ret = -EOPNOTSUPP;
  		else
  			return mtd->block_isbad(mtd, offs);
  		break;
  	}
  
  	case MEMSETBADBLOCK:
  	{
  		loff_t offs;
  
  		if (copy_from_user(&offs, argp, sizeof(loff_t)))
  			return -EFAULT;
  		if (!mtd->block_markbad)
  			ret = -EOPNOTSUPP;
  		else
  			return mtd->block_markbad(mtd, offs);
  		break;
  	}
  
  #ifdef CONFIG_HAVE_MTD_OTP
  	case OTPSELECT:
  	{
  		int mode;
  		if (copy_from_user(&mode, argp, sizeof(int)))
  			return -EFAULT;
  
  		mfi->mode = MTD_MODE_NORMAL;
  
  		ret = otp_select_filemode(mfi, mode);
  
  		file->f_pos = 0;
  		break;
  	}
  
  	case OTPGETREGIONCOUNT:
  	case OTPGETREGIONINFO:
  	{
  		struct otp_info *buf = kmalloc(4096, GFP_KERNEL);
  		if (!buf)
  			return -ENOMEM;
  		ret = -EOPNOTSUPP;
  		switch (mfi->mode) {
  		case MTD_MODE_OTP_FACTORY:
  			if (mtd->get_fact_prot_info)
  				ret = mtd->get_fact_prot_info(mtd, buf, 4096);
  			break;
  		case MTD_MODE_OTP_USER:
  			if (mtd->get_user_prot_info)
  				ret = mtd->get_user_prot_info(mtd, buf, 4096);
  			break;
  		default:
  			break;
  		}
  		if (ret >= 0) {
  			if (cmd == OTPGETREGIONCOUNT) {
  				int nbr = ret / sizeof(struct otp_info);
  				ret = copy_to_user(argp, &nbr, sizeof(int));
  			} else
  				ret = copy_to_user(argp, buf, ret);
  			if (ret)
  				ret = -EFAULT;
  		}
  		kfree(buf);
  		break;
  	}
  
  	case OTPLOCK:
  	{
  		struct otp_info oinfo;
  
  		if (mfi->mode != MTD_MODE_OTP_USER)
  			return -EINVAL;
  		if (copy_from_user(&oinfo, argp, sizeof(oinfo)))
  			return -EFAULT;
  		if (!mtd->lock_user_prot_reg)
  			return -EOPNOTSUPP;
  		ret = mtd->lock_user_prot_reg(mtd, oinfo.start, oinfo.length);
  		break;
  	}
  #endif
  
  	case ECCGETLAYOUT:
  	{
  		if (!mtd->ecclayout)
  			return -EOPNOTSUPP;
  
  		if (copy_to_user(argp, mtd->ecclayout,
  				 sizeof(struct nand_ecclayout)))
  			return -EFAULT;
  		break;
  	}
  
  	case ECCGETSTATS:
  	{
  		if (copy_to_user(argp, &mtd->ecc_stats,
  				 sizeof(struct mtd_ecc_stats)))
  			return -EFAULT;
  		break;
  	}
  
  	case MTDFILEMODE:
  	{
  		mfi->mode = 0;
  
  		switch(arg) {
  		case MTD_MODE_OTP_FACTORY:
  		case MTD_MODE_OTP_USER:
  			ret = otp_select_filemode(mfi, arg);
  			break;
  
  		case MTD_MODE_RAW:
  			if (!mtd->read_oob || !mtd->write_oob)
  				return -EOPNOTSUPP;
  			mfi->mode = arg;
  
  		case MTD_MODE_NORMAL:
  			break;
  		default:
  			ret = -EINVAL;
  		}
  		file->f_pos = 0;
  		break;
  	}
  
  	default:
  		ret = -ENOTTY;
  	}
  
  	return ret;
  } /* memory_ioctl */
  
  static long mtd_unlocked_ioctl(struct file *file, u_int cmd, u_long arg)
  {
  	int ret;
  
  	lock_kernel();
  	ret = mtd_ioctl(file, cmd, arg);
  	unlock_kernel();
  
  	return ret;
  }
  
  #ifdef CONFIG_COMPAT
  
  struct mtd_oob_buf32 {
  	u_int32_t start;
  	u_int32_t length;
  	compat_caddr_t ptr;	/* unsigned char* */
  };
  
  #define MEMWRITEOOB32		_IOWR('M', 3, struct mtd_oob_buf32)
  #define MEMREADOOB32		_IOWR('M', 4, struct mtd_oob_buf32)
  
  static long mtd_compat_ioctl(struct file *file, unsigned int cmd,
  	unsigned long arg)
  {
  	struct mtd_file_info *mfi = file->private_data;
  	struct mtd_info *mtd = mfi->mtd;
  	void __user *argp = compat_ptr(arg);
  	int ret = 0;
  
  	lock_kernel();
  
  	switch (cmd) {
  	case MEMWRITEOOB32:
  	{
  		struct mtd_oob_buf32 buf;
  		struct mtd_oob_buf32 __user *buf_user = argp;
  
  		if (copy_from_user(&buf, argp, sizeof(buf)))
  			ret = -EFAULT;
  		else
  			ret = mtd_do_writeoob(file, mtd, buf.start,
  				buf.length, compat_ptr(buf.ptr),
  				&buf_user->length);
  		break;
  	}
  
  	case MEMREADOOB32:
  	{
  		struct mtd_oob_buf32 buf;
  		struct mtd_oob_buf32 __user *buf_user = argp;
  
  		/* NOTE: writes return length to buf->start */
  		if (copy_from_user(&buf, argp, sizeof(buf)))
  			ret = -EFAULT;
  		else
  			ret = mtd_do_readoob(mtd, buf.start,
  				buf.length, compat_ptr(buf.ptr),
  				&buf_user->start);
  		break;
  	}
  	default:
  		ret = mtd_ioctl(file, cmd, (unsigned long)argp);
  	}
  
  	unlock_kernel();
  
  	return ret;
  }
  
  #endif /* CONFIG_COMPAT */
  
  /*
   * try to determine where a shared mapping can be made
   * - only supported for NOMMU at the moment (MMU can't doesn't copy private
   *   mappings)
   */
  #ifndef CONFIG_MMU
  static unsigned long mtd_get_unmapped_area(struct file *file,
  					   unsigned long addr,
  					   unsigned long len,
  					   unsigned long pgoff,
  					   unsigned long flags)
  {
  	struct mtd_file_info *mfi = file->private_data;
  	struct mtd_info *mtd = mfi->mtd;
  
  	if (mtd->get_unmapped_area) {
  		unsigned long offset;
  
  		if (addr != 0)
  			return (unsigned long) -EINVAL;
  
  		if (len > mtd->size || pgoff >= (mtd->size >> PAGE_SHIFT))
  			return (unsigned long) -EINVAL;
  
  		offset = pgoff << PAGE_SHIFT;
  		if (offset > mtd->size - len)
  			return (unsigned long) -EINVAL;
  
  		return mtd->get_unmapped_area(mtd, len, offset, flags);
  	}
  
  	/* can't map directly */
  	return (unsigned long) -ENOSYS;
  }
  #endif
  
  /*
   * set up a mapping for shared memory segments
   */
  static int mtd_mmap(struct file *file, struct vm_area_struct *vma)
  {
  #ifdef CONFIG_MMU
  	struct mtd_file_info *mfi = file->private_data;
  	struct mtd_info *mtd = mfi->mtd;
  	struct map_info *map = mtd->priv;
  	unsigned long start;
  	unsigned long off;
  	u32 len;
  
  	if (mtd->type == MTD_RAM || mtd->type == MTD_ROM) {
  		off = vma->vm_pgoff << PAGE_SHIFT;
  		start = map->phys;
  		len = PAGE_ALIGN((start & ~PAGE_MASK) + map->size);
  		start &= PAGE_MASK;
  		if ((vma->vm_end - vma->vm_start + off) > len)
  			return -EINVAL;
  
  		off += start;
  		vma->vm_pgoff = off >> PAGE_SHIFT;
  		vma->vm_flags |= VM_IO | VM_RESERVED;
  
  #ifdef pgprot_noncached
  		if (file->f_flags & O_DSYNC || off >= __pa(high_memory))
  			vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot);
  #endif
  		if (io_remap_pfn_range(vma, vma->vm_start, off >> PAGE_SHIFT,
  				       vma->vm_end - vma->vm_start,
  				       vma->vm_page_prot))
  			return -EAGAIN;
  
  		return 0;
  	}
  	return -ENOSYS;
  #else
  	return vma->vm_flags & VM_SHARED ? 0 : -ENOSYS;
  #endif
  }
  
  static const struct file_operations mtd_fops = {
  	.owner		= THIS_MODULE,
  	.llseek		= mtd_lseek,
  	.read		= mtd_read,
  	.write		= mtd_write,
  	.unlocked_ioctl	= mtd_unlocked_ioctl,
  #ifdef CONFIG_COMPAT
  	.compat_ioctl	= mtd_compat_ioctl,
  #endif
  	.open		= mtd_open,
  	.release	= mtd_close,
  	.mmap		= mtd_mmap,
  #ifndef CONFIG_MMU
  	.get_unmapped_area = mtd_get_unmapped_area,
  #endif
  };
  
  static int mtd_inodefs_get_sb(struct file_system_type *fs_type, int flags,
                                 const char *dev_name, void *data,
                                 struct vfsmount *mnt)
  {
          return get_sb_pseudo(fs_type, "mtd_inode:", NULL, MTD_INODE_FS_MAGIC,
                               mnt);
  }
  
  static struct file_system_type mtd_inodefs_type = {
         .name = "mtd_inodefs",
         .get_sb = mtd_inodefs_get_sb,
         .kill_sb = kill_anon_super,
  };
  
  static void mtdchar_notify_add(struct mtd_info *mtd)
  {
  }
  
  static void mtdchar_notify_remove(struct mtd_info *mtd)
  {
  	struct inode *mtd_ino = ilookup(mtd_inode_mnt->mnt_sb, mtd->index);
  
  	if (mtd_ino) {
  		/* Destroy the inode if it exists */
  		mtd_ino->i_nlink = 0;
  		iput(mtd_ino);
  	}
  }
  
  static struct mtd_notifier mtdchar_notifier = {
  	.add = mtdchar_notify_add,
  	.remove = mtdchar_notify_remove,
  };
  
  static int __init init_mtdchar(void)
  {
  	int ret;
  
  	ret = __register_chrdev(MTD_CHAR_MAJOR, 0, 1 << MINORBITS,
  				   "mtd", &mtd_fops);
  	if (ret < 0) {
  		pr_notice("Can't allocate major number %d for "
  				"Memory Technology Devices.\n", MTD_CHAR_MAJOR);
  		return ret;
  	}
  
  	ret = register_filesystem(&mtd_inodefs_type);
  	if (ret) {
  		pr_notice("Can't register mtd_inodefs filesystem: %d\n", ret);
  		goto err_unregister_chdev;
  	}
  
  	mtd_inode_mnt = kern_mount(&mtd_inodefs_type);
  	if (IS_ERR(mtd_inode_mnt)) {
  		ret = PTR_ERR(mtd_inode_mnt);
  		pr_notice("Error mounting mtd_inodefs filesystem: %d\n", ret);
  		goto err_unregister_filesystem;
  	}
  	register_mtd_user(&mtdchar_notifier);
  
  	return ret;
  
  err_unregister_filesystem:
  	unregister_filesystem(&mtd_inodefs_type);
  err_unregister_chdev:
  	__unregister_chrdev(MTD_CHAR_MAJOR, 0, 1 << MINORBITS, "mtd");
  	return ret;
  }
  
  static void __exit cleanup_mtdchar(void)
  {
  	unregister_mtd_user(&mtdchar_notifier);
  	mntput(mtd_inode_mnt);
  	unregister_filesystem(&mtd_inodefs_type);
  	__unregister_chrdev(MTD_CHAR_MAJOR, 0, 1 << MINORBITS, "mtd");
  }
  
  module_init(init_mtdchar);
  module_exit(cleanup_mtdchar);
  
  MODULE_ALIAS_CHARDEV_MAJOR(MTD_CHAR_MAJOR);
  
  MODULE_LICENSE("GPL");
  MODULE_AUTHOR("David Woodhouse <dwmw2@infradead.org>");
  MODULE_DESCRIPTION("Direct character-device access to MTD devices");
  MODULE_ALIAS_CHARDEV_MAJOR(MTD_CHAR_MAJOR);
  