static int mtd_ioctl(struct inode *inode, 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:
	{
		struct region_info_user ur;

		if (copy_from_user(&ur, argp, sizeof(struct region_info_user)))
			return -EFAULT;

		if (ur.regionindex >= mtd->numeraseregions)
			return -EINVAL;
		if (copy_to_user(argp, &(mtd->eraseregions[ur.regionindex]),
				sizeof(struct mtd_erase_region_info)))
			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:
	{
		struct erase_info *erase;

		if(!(file->f_mode & 2))
			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 (copy_from_user(&erase->addr, argp,
				    sizeof(struct erase_info_user))) {
				kfree(erase);
				return -EFAULT;
			}
			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_ops ops;
	        uint32_t retlen;

		if(!(file->f_mode & 2))
			return -EPERM;

		if (copy_from_user(&buf, argp, sizeof(struct mtd_oob_buf)))
			return -EFAULT;

		if (buf.length > 4096)
			return -EINVAL;

		if (!mtd->write_oob)
			ret = -EOPNOTSUPP;
		else
			ret = access_ok(VERIFY_READ, buf.ptr,
					buf.length) ? 0 : EFAULT;

		if (ret)
			return ret;

		ops.ooblen = buf.length;
		ops.ooboffs = buf.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(buf.length, GFP_KERNEL);
		if (!ops.oobbuf)
			return -ENOMEM;

		if (copy_from_user(ops.oobbuf, buf.ptr, buf.length)) {
			kfree(ops.oobbuf);
			return -EFAULT;
		}

		buf.start &= ~(mtd->oobsize - 1);
		ret = mtd->write_oob(mtd, buf.start, &ops);

		if (ops.oobretlen > 0xFFFFFFFFU)
			ret = -EOVERFLOW;
		retlen = ops.oobretlen;
		if (copy_to_user(&((struct mtd_oob_buf *)argp)->length,
				 &retlen, sizeof(buf.length)))
			ret = -EFAULT;

		kfree(ops.oobbuf);
		break;

	}

	case MEMREADOOB:
	{
		struct mtd_oob_buf buf;
		struct mtd_oob_ops ops;

		if (copy_from_user(&buf, argp, sizeof(struct mtd_oob_buf)))
			return -EFAULT;

		if (buf.length > 4096)
			return -EINVAL;

		if (!mtd->read_oob)
			ret = -EOPNOTSUPP;
		else
			ret = access_ok(VERIFY_WRITE, buf.ptr,
					buf.length) ? 0 : -EFAULT;
		if (ret)
			return ret;

		ops.ooblen = buf.length;
		ops.ooboffs = buf.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(buf.length, GFP_KERNEL);
		if (!ops.oobbuf)
			return -ENOMEM;

		buf.start &= ~(mtd->oobsize - 1);
		ret = mtd->read_oob(mtd, buf.start, &ops);

		if (put_user(ops.oobretlen, (uint32_t __user *)argp))
			ret = -EFAULT;
		else if (ops.oobretlen && copy_to_user(buf.ptr, ops.oobbuf,
						    ops.oobretlen))
			ret = -EFAULT;

		kfree(ops.oobbuf);
		break;
	}

	case MEMLOCK:
	{
		struct erase_info_user info;

		if (copy_from_user(&info, argp, sizeof(info)))
			return -EFAULT;

		if (!mtd->lock)
			ret = -EOPNOTSUPP;
		else
			ret = mtd->lock(mtd, info.start, info.length);
		break;
	}

	case MEMUNLOCK:
	{
		struct erase_info_user info;

		if (copy_from_user(&info, argp, sizeof(info)))
			return -EFAULT;

		if (!mtd->unlock)
			ret = -EOPNOTSUPP;
		else
			ret = mtd->unlock(mtd, info.start, info.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;
	}

#if defined(CONFIG_MTD_OTP) || defined(CONFIG_MTD_ONENAND_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 info;

		if (mfi->mode != MTD_MODE_OTP_USER)
			return -EINVAL;
		if (copy_from_user(&info, argp, sizeof(info)))
			return -EFAULT;
		if (!mtd->lock_user_prot_reg)
			return -EOPNOTSUPP;
		ret = mtd->lock_user_prot_reg(mtd, info.start, info.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 */