drivers/mtd/mtdchar.c - maze/linux - Git at Google

 /*
  * $Id: mtdchar.c,v 1.76 2005/11/07 11:14:20 gleixner Exp $
  *
  * Character-device access to raw MTD devices.
  *
  */

 #include <linux/config.h>
 #include <linux/device.h>
 #include <linux/fs.h>
 #include <linux/init.h>
 #include <linux/kernel.h>
 #include <linux/module.h>
 #include <linux/slab.h>
 #include <linux/sched.h>

 #include <linux/mtd/mtd.h>
 #include <linux/mtd/compatmac.h>

 #include <asm/uaccess.h>

 static struct class *mtd_class;

 static void mtd_notify_add(struct mtd_info* mtd)
 {
 	if (!mtd)
 		return;

 	class_device_create(mtd_class, NULL, MKDEV(MTD_CHAR_MAJOR, mtd->index*2),
 			    NULL, "mtd%d", mtd->index);

 	class_device_create(mtd_class, NULL,
 			    MKDEV(MTD_CHAR_MAJOR, mtd->index*2+1),
 			    NULL, "mtd%dro", mtd->index);
 }

 static void mtd_notify_remove(struct mtd_info* mtd)
 {
 	if (!mtd)
 		return;

 	class_device_destroy(mtd_class, MKDEV(MTD_CHAR_MAJOR, mtd->index*2));
 	class_device_destroy(mtd_class, MKDEV(MTD_CHAR_MAJOR, mtd->index*2+1));
 }

 static struct mtd_notifier notifier = {
 	.add	= mtd_notify_add,
 	.remove	= mtd_notify_remove,
 };

 /*
  * We use file->private_data to store a pointer to the MTDdevice.
  * Since alighment is at least 32 bits, we have 2 bits free for OTP
  * modes as well.
  */

 #define TO_MTD(file) (struct mtd_info *)((long)((file)->private_data) & ~3L)

 #define MTD_MODE_OTP_FACT	1
 #define MTD_MODE_OTP_USER	2
 #define MTD_MODE(file)		((long)((file)->private_data) & 3)

 #define SET_MTD_MODE(file, mode) \
 	do { long __p = (long)((file)->private_data); \
 	     (file)->private_data = (void *)((__p & ~3L) | mode); } while (0)

 static loff_t mtd_lseek (struct file *file, loff_t offset, int orig)
 {
 	struct mtd_info *mtd = TO_MTD(file);

 	switch (orig) {
 	case 0:
 		/* SEEK_SET */
 		break;
 	case 1:
 		/* SEEK_CUR */
 		offset += file->f_pos;
 		break;
 	case 2:
 		/* 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;
 	struct mtd_info *mtd;

 	DEBUG(MTD_DEBUG_LEVEL0, "MTD_open\n");

 	if (devnum >= MAX_MTD_DEVICES)
 		return -ENODEV;

 	/* You can't open the RO devices RW */
 	if ((file->f_mode & 2) && (minor & 1))
 		return -EACCES;

 	mtd = get_mtd_device(NULL, devnum);

 	if (!mtd)
 		return -ENODEV;

 	if (MTD_ABSENT == mtd->type) {
 		put_mtd_device(mtd);
 		return -ENODEV;
 	}

 	file->private_data = mtd;

 	/* You can't open it RW if it's not a writeable device */
 	if ((file->f_mode & 2) && !(mtd->flags & MTD_WRITEABLE)) {
 		put_mtd_device(mtd);
 		return -EACCES;
 	}

 	return 0;
 } /* mtd_open */

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

 static int mtd_close(struct inode *inode, struct file *file)
 {
 	struct mtd_info *mtd;

 	DEBUG(MTD_DEBUG_LEVEL0, "MTD_close\n");

 	mtd = TO_MTD(file);

 	if (mtd->sync)
 		mtd->sync(mtd);

 	put_mtd_device(mtd);

 	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_info *mtd = TO_MTD(file);
 	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 (MTD_MODE(file)) {
 		case MTD_MODE_OTP_FACT:
 			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;
 		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 !
 		 * Userspace software which accesses NAND this way
 		 * must be aware of the fact that it deals with NAND
 		 */
 		if (!ret || (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_info *mtd = TO_MTD(file);
 	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 (MTD_MODE(file)) {
 		case MTD_MODE_OTP_FACT:
 			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;
 		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);
 }

 static int mtd_ioctl(struct inode *inode, struct file *file,
 		     u_int cmd, u_long arg)
 {
 	struct mtd_info *mtd = TO_MTD(file);
 	void __user *argp = (void __user *)arg;
 	int ret = 0;
 	u_long size;

 	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:
 		if (copy_to_user(argp, mtd, sizeof(struct mtd_info_user)))
 			return -EFAULT;
 		break;

 	case MEMERASE:
 	{
 		struct erase_info *erase;

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

 		erase=kmalloc(sizeof(struct erase_info),GFP_KERNEL);
 		if (!erase)
 			ret = -ENOMEM;
 		else {
 			wait_queue_head_t waitq;
 			DECLARE_WAITQUEUE(wait, current);

 			init_waitqueue_head(&waitq);

 			memset (erase,0,sizeof(struct erase_info));
 			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;
 		void *databuf;
 		ssize_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 > 0x4096)
 			return -EINVAL;

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

 		if (ret)
 			return ret;

 		databuf = kmalloc(buf.length, GFP_KERNEL);
 		if (!databuf)
 			return -ENOMEM;

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

 		ret = (mtd->write_oob)(mtd, buf.start, buf.length, &retlen, databuf);

 		if (copy_to_user(argp + sizeof(uint32_t), &retlen, sizeof(uint32_t)))
 			ret = -EFAULT;

 		kfree(databuf);
 		break;

 	}

 	case MEMREADOOB:
 	{
 		struct mtd_oob_buf buf;
 		void *databuf;
 		ssize_t retlen;

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

 		if (buf.length > 0x4096)
 			return -EINVAL;

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

 		if (ret)
 			return ret;

 		databuf = kmalloc(buf.length, GFP_KERNEL);
 		if (!databuf)
 			return -ENOMEM;

 		ret = (mtd->read_oob)(mtd, buf.start, buf.length, &retlen, databuf);

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

 		kfree(databuf);
 		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));

 		if (copy_to_user(argp, &oi, sizeof(struct nand_oobinfo)))
 			return -EFAULT;
 		break;
 	}

 	case ECCGETLAYOUT:

 		if (!mtd->ecclayout)
 			return -EOPNOTSUPP;

 		if (copy_to_user(argp, &mtd->ecclayout,
 				 sizeof(struct nand_ecclayout)))
 			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;
 		SET_MTD_MODE(file, 0);
 		switch (mode) {
 		case MTD_OTP_FACTORY:
 			if (!mtd->read_fact_prot_reg)
 				ret = -EOPNOTSUPP;
 			else
 				SET_MTD_MODE(file, MTD_MODE_OTP_FACT);
 			break;
 		case MTD_OTP_USER:
 			if (!mtd->read_fact_prot_reg)
 				ret = -EOPNOTSUPP;
 			else
 				SET_MTD_MODE(file, MTD_MODE_OTP_USER);
 			break;
 		default:
 			ret = -EINVAL;
 		case MTD_OTP_OFF:
 			break;
 		}
 		file->f_pos = 0;
 		break;
 	}

 	case OTPGETREGIONCOUNT:
 	case OTPGETREGIONINFO:
 	{
 		struct otp_info *buf = kmalloc(4096, GFP_KERNEL);
 		if (!buf)
 			return -ENOMEM;
 		ret = -EOPNOTSUPP;
 		switch (MTD_MODE(file)) {
 		case MTD_MODE_OTP_FACT:
 			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;
 		}
 		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 (MTD_MODE(file) != 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

 	default:
 		ret = -ENOTTY;
 	}

 	return ret;
 } /* memory_ioctl */

 static struct file_operations mtd_fops = {
 	.owner		= THIS_MODULE,
 	.llseek		= mtd_lseek,
 	.read		= mtd_read,
 	.write		= mtd_write,
 	.ioctl		= mtd_ioctl,
 	.open		= mtd_open,
 	.release	= mtd_close,
 };

 static int __init init_mtdchar(void)
 {
 	if (register_chrdev(MTD_CHAR_MAJOR, "mtd", &mtd_fops)) {
 		printk(KERN_NOTICE "Can't allocate major number %d for Memory Technology Devices.\n",
 		       MTD_CHAR_MAJOR);
 		return -EAGAIN;
 	}

 	mtd_class = class_create(THIS_MODULE, "mtd");

 	if (IS_ERR(mtd_class)) {
 		printk(KERN_ERR "Error creating mtd class.\n");
 		unregister_chrdev(MTD_CHAR_MAJOR, "mtd");
 		return PTR_ERR(mtd_class);
 	}

 	register_mtd_user(&notifier);
 	return 0;
 }

 static void __exit cleanup_mtdchar(void)
 {
 	unregister_mtd_user(&notifier);
 	class_destroy(mtd_class);
 	unregister_chrdev(MTD_CHAR_MAJOR, "mtd");
 }

 module_init(init_mtdchar);
 module_exit(cleanup_mtdchar);


 MODULE_LICENSE("GPL");
 MODULE_AUTHOR("David Woodhouse <dwmw2@infradead.org>");
 MODULE_DESCRIPTION("Direct character-device access to MTD devices");
	/*
	* $Id: mtdchar.c,v 1.76 2005/11/07 11:14:20 gleixner Exp $
	*
	* Character-device access to raw MTD devices.
	*
	*/

	#include <linux/config.h>
	#include <linux/device.h>
	#include <linux/fs.h>
	#include <linux/init.h>
	#include <linux/kernel.h>
	#include <linux/module.h>
	#include <linux/slab.h>
	#include <linux/sched.h>

	#include <linux/mtd/mtd.h>
	#include <linux/mtd/compatmac.h>

	#include <asm/uaccess.h>

	static struct class *mtd_class;

	static void mtd_notify_add(struct mtd_info* mtd)
	{
	if (!mtd)
	return;

	class_device_create(mtd_class, NULL, MKDEV(MTD_CHAR_MAJOR, mtd->index*2),
	NULL, "mtd%d", mtd->index);

	class_device_create(mtd_class, NULL,
	MKDEV(MTD_CHAR_MAJOR, mtd->index*2+1),
	NULL, "mtd%dro", mtd->index);
	}

	static void mtd_notify_remove(struct mtd_info* mtd)
	{
	if (!mtd)
	return;

	class_device_destroy(mtd_class, MKDEV(MTD_CHAR_MAJOR, mtd->index*2));
	class_device_destroy(mtd_class, MKDEV(MTD_CHAR_MAJOR, mtd->index*2+1));
	}

	static struct mtd_notifier notifier = {
	.add = mtd_notify_add,
	.remove = mtd_notify_remove,
	};

	/*
	* We use file->private_data to store a pointer to the MTDdevice.
	* Since alighment is at least 32 bits, we have 2 bits free for OTP
	* modes as well.
	*/

	#define TO_MTD(file) (struct mtd_info *)((long)((file)->private_data) & ~3L)

	#define MTD_MODE_OTP_FACT 1
	#define MTD_MODE_OTP_USER 2
	#define MTD_MODE(file) ((long)((file)->private_data) & 3)

	#define SET_MTD_MODE(file, mode) \
	do { long __p = (long)((file)->private_data); \
	(file)->private_data = (void *)((__p & ~3L) \| mode); } while (0)

	static loff_t mtd_lseek (struct file *file, loff_t offset, int orig)
	{
	struct mtd_info *mtd = TO_MTD(file);

	switch (orig) {
	case 0:
	/* SEEK_SET */
	break;
	case 1:
	/* SEEK_CUR */
	offset += file->f_pos;
	break;
	case 2:
	/* 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;
	struct mtd_info *mtd;

	DEBUG(MTD_DEBUG_LEVEL0, "MTD_open\n");

	if (devnum >= MAX_MTD_DEVICES)
	return -ENODEV;

	/* You can't open the RO devices RW */
	if ((file->f_mode & 2) && (minor & 1))
	return -EACCES;

	mtd = get_mtd_device(NULL, devnum);

	if (!mtd)
	return -ENODEV;

	if (MTD_ABSENT == mtd->type) {
	put_mtd_device(mtd);
	return -ENODEV;
	}

	file->private_data = mtd;

	/* You can't open it RW if it's not a writeable device */
	if ((file->f_mode & 2) && !(mtd->flags & MTD_WRITEABLE)) {
	put_mtd_device(mtd);
	return -EACCES;
	}

	return 0;
	} /* mtd_open */

	/====================================================================/

	static int mtd_close(struct inode inode, struct file file)
	{
	struct mtd_info *mtd;

	DEBUG(MTD_DEBUG_LEVEL0, "MTD_close\n");

	mtd = TO_MTD(file);

	if (mtd->sync)
	mtd->sync(mtd);

	put_mtd_device(mtd);

	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_info *mtd = TO_MTD(file);
	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 (MTD_MODE(file)) {
	case MTD_MODE_OTP_FACT:
	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;
	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 !
	* Userspace software which accesses NAND this way
	* must be aware of the fact that it deals with NAND
	*/
	if (!ret \|\| (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_info *mtd = TO_MTD(file);
	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 (MTD_MODE(file)) {
	case MTD_MODE_OTP_FACT:
	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;
	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);
	}

	static int mtd_ioctl(struct inode inode, struct file file,
	u_int cmd, u_long arg)
	{
	struct mtd_info *mtd = TO_MTD(file);
	void __user argp = (void __user )arg;
	int ret = 0;
	u_long size;

	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:
	if (copy_to_user(argp, mtd, sizeof(struct mtd_info_user)))
	return -EFAULT;
	break;

	case MEMERASE:
	{
	struct erase_info *erase;

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

	erase=kmalloc(sizeof(struct erase_info),GFP_KERNEL);
	if (!erase)
	ret = -ENOMEM;
	else {
	wait_queue_head_t waitq;
	DECLARE_WAITQUEUE(wait, current);

	init_waitqueue_head(&waitq);

	memset (erase,0,sizeof(struct erase_info));
	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;
	void *databuf;
	ssize_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 > 0x4096)
	return -EINVAL;

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

	if (ret)
	return ret;

	databuf = kmalloc(buf.length, GFP_KERNEL);
	if (!databuf)
	return -ENOMEM;

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

	ret = (mtd->write_oob)(mtd, buf.start, buf.length, &retlen, databuf);

	if (copy_to_user(argp + sizeof(uint32_t), &retlen, sizeof(uint32_t)))
	ret = -EFAULT;

	kfree(databuf);
	break;

	}

	case MEMREADOOB:
	{
	struct mtd_oob_buf buf;
	void *databuf;
	ssize_t retlen;

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

	if (buf.length > 0x4096)
	return -EINVAL;

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

	if (ret)
	return ret;

	databuf = kmalloc(buf.length, GFP_KERNEL);
	if (!databuf)
	return -ENOMEM;

	ret = (mtd->read_oob)(mtd, buf.start, buf.length, &retlen, databuf);

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

	kfree(databuf);
	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));

	if (copy_to_user(argp, &oi, sizeof(struct nand_oobinfo)))
	return -EFAULT;
	break;
	}

	case ECCGETLAYOUT:

	if (!mtd->ecclayout)
	return -EOPNOTSUPP;

	if (copy_to_user(argp, &mtd->ecclayout,
	sizeof(struct nand_ecclayout)))
	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;
	SET_MTD_MODE(file, 0);
	switch (mode) {
	case MTD_OTP_FACTORY:
	if (!mtd->read_fact_prot_reg)
	ret = -EOPNOTSUPP;
	else
	SET_MTD_MODE(file, MTD_MODE_OTP_FACT);
	break;
	case MTD_OTP_USER:
	if (!mtd->read_fact_prot_reg)
	ret = -EOPNOTSUPP;
	else
	SET_MTD_MODE(file, MTD_MODE_OTP_USER);
	break;
	default:
	ret = -EINVAL;
	case MTD_OTP_OFF:
	break;
	}
	file->f_pos = 0;
	break;
	}

	case OTPGETREGIONCOUNT:
	case OTPGETREGIONINFO:
	{
	struct otp_info *buf = kmalloc(4096, GFP_KERNEL);
	if (!buf)
	return -ENOMEM;
	ret = -EOPNOTSUPP;
	switch (MTD_MODE(file)) {
	case MTD_MODE_OTP_FACT:
	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;
	}
	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 (MTD_MODE(file) != 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

	default:
	ret = -ENOTTY;
	}

	return ret;
	} /* memory_ioctl */

	static struct file_operations mtd_fops = {
	.owner = THIS_MODULE,
	.llseek = mtd_lseek,
	.read = mtd_read,
	.write = mtd_write,
	.ioctl = mtd_ioctl,
	.open = mtd_open,
	.release = mtd_close,
	};

	static int __init init_mtdchar(void)
	{
	if (register_chrdev(MTD_CHAR_MAJOR, "mtd", &mtd_fops)) {
	printk(KERN_NOTICE "Can't allocate major number %d for Memory Technology Devices.\n",
	MTD_CHAR_MAJOR);
	return -EAGAIN;
	}

	mtd_class = class_create(THIS_MODULE, "mtd");

	if (IS_ERR(mtd_class)) {
	printk(KERN_ERR "Error creating mtd class.\n");
	unregister_chrdev(MTD_CHAR_MAJOR, "mtd");
	return PTR_ERR(mtd_class);
	}

	register_mtd_user(&notifier);
	return 0;
	}

	static void __exit cleanup_mtdchar(void)
	{
	unregister_mtd_user(&notifier);
	class_destroy(mtd_class);
	unregister_chrdev(MTD_CHAR_MAJOR, "mtd");
	}

	module_init(init_mtdchar);
	module_exit(cleanup_mtdchar);


	MODULE_LICENSE("GPL");
	MODULE_AUTHOR("David Woodhouse <dwmw2@infradead.org>");
	MODULE_DESCRIPTION("Direct character-device access to MTD devices");