mtd, ubi, ubifs: resync with Linux-3.14

resync ubi subsystem with linux:

commit 455c6fdbd219161bd09b1165f11699d6d73de11c
Author: Linus Torvalds <torvalds@linux-foundation.org>
Date:   Sun Mar 30 20:40:15 2014 -0700

    Linux 3.14

A nice side effect of this, is we introduce UBI Fastmap support
to U-Boot.

Signed-off-by: Heiko Schocher <hs@denx.de>
Signed-off-by: Tom Rini <trini@ti.com>
Cc: Marek Vasut <marex@denx.de>
Cc: Sergey Lapin <slapin@ossfans.org>
Cc: Scott Wood <scottwood@freescale.com>
Cc: Joerg Krause <jkrause@posteo.de>

1 files changed, 1040 insertions, 72 deletions

diff --git a/drivers/mtd/mtdcore.c b/drivers/mtd/mtdcore.c
index 0a38fbef14..796ac0729e 100644
--- a/drivers/mtd/mtdcore.c
+++ b/drivers/mtd/mtdcore.c
@@ -2,130 +2,767 @@
  * Core registration and callback routines for MTD
  * drivers and users.
  *
- * This program is free software; you can redistribute it and/or modify
- * it under the terms of the GNU General Public License version 2 as
- * published by the Free Software Foundation.
+ * Copyright © 1999-2010 David Woodhouse <dwmw2@infradead.org>
+ * Copyright © 2006      Red Hat UK Limited 
+ *
+ * SPDX-License-Identifier:	GPL-2.0+
+ *
  */
 
-#include <linux/mtd/mtd.h>
+#define __UBOOT__
+#ifndef __UBOOT__
+#include <linux/module.h>
+#include <linux/kernel.h>
+#include <linux/ptrace.h>
+#include <linux/seq_file.h>
+#include <linux/string.h>
+#include <linux/timer.h>
+#include <linux/major.h>
+#include <linux/fs.h>
+#include <linux/err.h>
+#include <linux/ioctl.h>
+#include <linux/init.h>
+#include <linux/proc_fs.h>
+#include <linux/idr.h>
+#include <linux/backing-dev.h>
+#include <linux/gfp.h>
+#include <linux/slab.h>
+#else
 #include <linux/compat.h>
+#include <linux/err.h>
 #include <ubi_uboot.h>
+#endif
+
+#include <linux/mtd/mtd.h>
+#include <linux/mtd/partitions.h>
+
+#include "mtdcore.h"
+
+#ifndef __UBOOT__
+/*
+ * backing device capabilities for non-mappable devices (such as NAND flash)
+ * - permits private mappings, copies are taken of the data
+ */
+static struct backing_dev_info mtd_bdi_unmappable = {
+	.capabilities	= BDI_CAP_MAP_COPY,
+};
+
+/*
+ * backing device capabilities for R/O mappable devices (such as ROM)
+ * - permits private mappings, copies are taken of the data
+ * - permits non-writable shared mappings
+ */
+static struct backing_dev_info mtd_bdi_ro_mappable = {
+	.capabilities	= (BDI_CAP_MAP_COPY | BDI_CAP_MAP_DIRECT |
+			   BDI_CAP_EXEC_MAP | BDI_CAP_READ_MAP),
+};
+
+/*
+ * backing device capabilities for writable mappable devices (such as RAM)
+ * - permits private mappings, copies are taken of the data
+ * - permits non-writable shared mappings
+ */
+static struct backing_dev_info mtd_bdi_rw_mappable = {
+	.capabilities	= (BDI_CAP_MAP_COPY | BDI_CAP_MAP_DIRECT |
+			   BDI_CAP_EXEC_MAP | BDI_CAP_READ_MAP |
+			   BDI_CAP_WRITE_MAP),
+};
+
+static int mtd_cls_suspend(struct device *dev, pm_message_t state);
+static int mtd_cls_resume(struct device *dev);
 
+static struct class mtd_class = {
+	.name = "mtd",
+	.owner = THIS_MODULE,
+	.suspend = mtd_cls_suspend,
+	.resume = mtd_cls_resume,
+};
+#else
 struct mtd_info *mtd_table[MAX_MTD_DEVICES];
 
+#define MAX_IDR_ID	64
+
+struct idr_layer {
+	int	used;
+	void	*ptr;
+};
+
+struct idr {
+	struct idr_layer id[MAX_IDR_ID];
+};
+
+#define DEFINE_IDR(name)	struct idr name;
+
+void idr_remove(struct idr *idp, int id)
+{
+	if (idp->id[id].used)
+		idp->id[id].used = 0;
+
+	return;
+}
+void *idr_find(struct idr *idp, int id)
+{
+	if (idp->id[id].used)
+		return idp->id[id].ptr;
+
+	return NULL;
+}
+
+void *idr_get_next(struct idr *idp, int *next)
+{
+	void *ret;
+	int id = *next;
+
+	ret = idr_find(idp, id);
+	if (ret) {
+		id ++;
+		if (!idp->id[id].used)
+			id = 0;
+		*next = id;
+	} else {
+		*next = 0;
+	}
+	
+	return ret;
+}
+
+int idr_alloc(struct idr *idp, void *ptr, int start, int end, gfp_t gfp_mask)
+{
+	struct idr_layer *idl;
+	int i = 0;
+
+	while (i < MAX_IDR_ID) {
+		idl = &idp->id[i];
+		if (idl->used == 0) {
+			idl->used = 1;
+			idl->ptr = ptr;
+			return i;
+		}
+		i++;
+	}
+	return -ENOSPC;
+}
+#endif
+
+static DEFINE_IDR(mtd_idr);
+
+/* These are exported solely for the purpose of mtd_blkdevs.c. You
+   should not use them for _anything_ else */
+DEFINE_MUTEX(mtd_table_mutex);
+EXPORT_SYMBOL_GPL(mtd_table_mutex);
+
+struct mtd_info *__mtd_next_device(int i)
+{
+	return idr_get_next(&mtd_idr, &i);
+}
+EXPORT_SYMBOL_GPL(__mtd_next_device);
+
+#ifndef __UBOOT__
+static LIST_HEAD(mtd_notifiers);
+
+
+#define MTD_DEVT(index) MKDEV(MTD_CHAR_MAJOR, (index)*2)
+
+/* REVISIT once MTD uses the driver model better, whoever allocates
+ * the mtd_info will probably want to use the release() hook...
+ */
+static void mtd_release(struct device *dev)
+{
+	struct mtd_info __maybe_unused *mtd = dev_get_drvdata(dev);
+	dev_t index = MTD_DEVT(mtd->index);
+
+	/* remove /dev/mtdXro node if needed */
+	if (index)
+		device_destroy(&mtd_class, index + 1);
+}
+
+static int mtd_cls_suspend(struct device *dev, pm_message_t state)
+{
+	struct mtd_info *mtd = dev_get_drvdata(dev);
+
+	return mtd ? mtd_suspend(mtd) : 0;
+}
+
+static int mtd_cls_resume(struct device *dev)
+{
+	struct mtd_info *mtd = dev_get_drvdata(dev);
+
+	if (mtd)
+		mtd_resume(mtd);
+	return 0;
+}
+
+static ssize_t mtd_type_show(struct device *dev,
+		struct device_attribute *attr, char *buf)
+{
+	struct mtd_info *mtd = dev_get_drvdata(dev);
+	char *type;
+
+	switch (mtd->type) {
+	case MTD_ABSENT:
+		type = "absent";
+		break;
+	case MTD_RAM:
+		type = "ram";
+		break;
+	case MTD_ROM:
+		type = "rom";
+		break;
+	case MTD_NORFLASH:
+		type = "nor";
+		break;
+	case MTD_NANDFLASH:
+		type = "nand";
+		break;
+	case MTD_DATAFLASH:
+		type = "dataflash";
+		break;
+	case MTD_UBIVOLUME:
+		type = "ubi";
+		break;
+	case MTD_MLCNANDFLASH:
+		type = "mlc-nand";
+		break;
+	default:
+		type = "unknown";
+	}
+
+	return snprintf(buf, PAGE_SIZE, "%s\n", type);
+}
+static DEVICE_ATTR(type, S_IRUGO, mtd_type_show, NULL);
+
+static ssize_t mtd_flags_show(struct device *dev,
+		struct device_attribute *attr, char *buf)
+{
+	struct mtd_info *mtd = dev_get_drvdata(dev);
+
+	return snprintf(buf, PAGE_SIZE, "0x%lx\n", (unsigned long)mtd->flags);
+
+}
+static DEVICE_ATTR(flags, S_IRUGO, mtd_flags_show, NULL);
+
+static ssize_t mtd_size_show(struct device *dev,
+		struct device_attribute *attr, char *buf)
+{
+	struct mtd_info *mtd = dev_get_drvdata(dev);
+
+	return snprintf(buf, PAGE_SIZE, "%llu\n",
+		(unsigned long long)mtd->size);
+
+}
+static DEVICE_ATTR(size, S_IRUGO, mtd_size_show, NULL);
+
+static ssize_t mtd_erasesize_show(struct device *dev,
+		struct device_attribute *attr, char *buf)
+{
+	struct mtd_info *mtd = dev_get_drvdata(dev);
+
+	return snprintf(buf, PAGE_SIZE, "%lu\n", (unsigned long)mtd->erasesize);
+
+}
+static DEVICE_ATTR(erasesize, S_IRUGO, mtd_erasesize_show, NULL);
+
+static ssize_t mtd_writesize_show(struct device *dev,
+		struct device_attribute *attr, char *buf)
+{
+	struct mtd_info *mtd = dev_get_drvdata(dev);
+
+	return snprintf(buf, PAGE_SIZE, "%lu\n", (unsigned long)mtd->writesize);
+
+}
+static DEVICE_ATTR(writesize, S_IRUGO, mtd_writesize_show, NULL);
+
+static ssize_t mtd_subpagesize_show(struct device *dev,
+		struct device_attribute *attr, char *buf)
+{
+	struct mtd_info *mtd = dev_get_drvdata(dev);
+	unsigned int subpagesize = mtd->writesize >> mtd->subpage_sft;
+
+	return snprintf(buf, PAGE_SIZE, "%u\n", subpagesize);
+
+}
+static DEVICE_ATTR(subpagesize, S_IRUGO, mtd_subpagesize_show, NULL);
+
+static ssize_t mtd_oobsize_show(struct device *dev,
+		struct device_attribute *attr, char *buf)
+{
+	struct mtd_info *mtd = dev_get_drvdata(dev);
+
+	return snprintf(buf, PAGE_SIZE, "%lu\n", (unsigned long)mtd->oobsize);
+
+}
+static DEVICE_ATTR(oobsize, S_IRUGO, mtd_oobsize_show, NULL);
+
+static ssize_t mtd_numeraseregions_show(struct device *dev,
+		struct device_attribute *attr, char *buf)
+{
+	struct mtd_info *mtd = dev_get_drvdata(dev);
+
+	return snprintf(buf, PAGE_SIZE, "%u\n", mtd->numeraseregions);
+
+}
+static DEVICE_ATTR(numeraseregions, S_IRUGO, mtd_numeraseregions_show,
+	NULL);
+
+static ssize_t mtd_name_show(struct device *dev,
+		struct device_attribute *attr, char *buf)
+{
+	struct mtd_info *mtd = dev_get_drvdata(dev);
+
+	return snprintf(buf, PAGE_SIZE, "%s\n", mtd->name);
+
+}
+static DEVICE_ATTR(name, S_IRUGO, mtd_name_show, NULL);
+
+static ssize_t mtd_ecc_strength_show(struct device *dev,
+				     struct device_attribute *attr, char *buf)
+{
+	struct mtd_info *mtd = dev_get_drvdata(dev);
+
+	return snprintf(buf, PAGE_SIZE, "%u\n", mtd->ecc_strength);
+}
+static DEVICE_ATTR(ecc_strength, S_IRUGO, mtd_ecc_strength_show, NULL);
+
+static ssize_t mtd_bitflip_threshold_show(struct device *dev,
+					  struct device_attribute *attr,
+					  char *buf)
+{
+	struct mtd_info *mtd = dev_get_drvdata(dev);
+
+	return snprintf(buf, PAGE_SIZE, "%u\n", mtd->bitflip_threshold);
+}
+
+static ssize_t mtd_bitflip_threshold_store(struct device *dev,
+					   struct device_attribute *attr,
+					   const char *buf, size_t count)
+{
+	struct mtd_info *mtd = dev_get_drvdata(dev);
+	unsigned int bitflip_threshold;
+	int retval;
+
+	retval = kstrtouint(buf, 0, &bitflip_threshold);
+	if (retval)
+		return retval;
+
+	mtd->bitflip_threshold = bitflip_threshold;
+	return count;
+}
+static DEVICE_ATTR(bitflip_threshold, S_IRUGO | S_IWUSR,
+		   mtd_bitflip_threshold_show,
+		   mtd_bitflip_threshold_store);
+
+static ssize_t mtd_ecc_step_size_show(struct device *dev,
+		struct device_attribute *attr, char *buf)
+{
+	struct mtd_info *mtd = dev_get_drvdata(dev);
+
+	return snprintf(buf, PAGE_SIZE, "%u\n", mtd->ecc_step_size);
+
+}
+static DEVICE_ATTR(ecc_step_size, S_IRUGO, mtd_ecc_step_size_show, NULL);
+
+static struct attribute *mtd_attrs[] = {
+	&dev_attr_type.attr,
+	&dev_attr_flags.attr,
+	&dev_attr_size.attr,
+	&dev_attr_erasesize.attr,
+	&dev_attr_writesize.attr,
+	&dev_attr_subpagesize.attr,
+	&dev_attr_oobsize.attr,
+	&dev_attr_numeraseregions.attr,
+	&dev_attr_name.attr,
+	&dev_attr_ecc_strength.attr,
+	&dev_attr_ecc_step_size.attr,
+	&dev_attr_bitflip_threshold.attr,
+	NULL,
+};
+ATTRIBUTE_GROUPS(mtd);
+
+static struct device_type mtd_devtype = {
+	.name		= "mtd",
+	.groups		= mtd_groups,
+	.release	= mtd_release,
+};
+#endif
+
+/**
+ *	add_mtd_device - register an MTD device
+ *	@mtd: pointer to new MTD device info structure
+ *
+ *	Add a device to the list of MTD devices present in the system, and
+ *	notify each currently active MTD 'user' of its arrival. Returns
+ *	zero on success or 1 on failure, which currently will only happen
+ *	if there is insufficient memory or a sysfs error.
+ */
+
 int add_mtd_device(struct mtd_info *mtd)
 {
-	int i;
+#ifndef __UBOOT__
+	struct mtd_notifier *not;
+#endif
+	int i, error;
+
+#ifndef __UBOOT__
+	if (!mtd->backing_dev_info) {
+		switch (mtd->type) {
+		case MTD_RAM:
+			mtd->backing_dev_info = &mtd_bdi_rw_mappable;
+			break;
+		case MTD_ROM:
+			mtd->backing_dev_info = &mtd_bdi_ro_mappable;
+			break;
+		default:
+			mtd->backing_dev_info = &mtd_bdi_unmappable;
+			break;
+		}
+	}
+#endif
 
 	BUG_ON(mtd->writesize == 0);
+	mutex_lock(&mtd_table_mutex);
 
-	for (i = 0; i < MAX_MTD_DEVICES; i++)
-		if (!mtd_table[i]) {
-			mtd_table[i] = mtd;
-			mtd->index = i;
-			mtd->usecount = 0;
+	i = idr_alloc(&mtd_idr, mtd, 0, 0, GFP_KERNEL);
+	if (i < 0)
+		goto fail_locked;
 
-			/* default value if not set by driver */
-			if (mtd->bitflip_threshold == 0)
-				mtd->bitflip_threshold = mtd->ecc_strength;
+	mtd->index = i;
+	mtd->usecount = 0;
 
+	/* default value if not set by driver */
+	if (mtd->bitflip_threshold == 0)
+		mtd->bitflip_threshold = mtd->ecc_strength;
 
-			/* No need to get a refcount on the module containing
-			   the notifier, since we hold the mtd_table_mutex */
+	if (is_power_of_2(mtd->erasesize))
+		mtd->erasesize_shift = ffs(mtd->erasesize) - 1;
+	else
+		mtd->erasesize_shift = 0;
 
-			/* We _know_ we aren't being removed, because
-			   our caller is still holding us here. So none
-			   of this try_ nonsense, and no bitching about it
-			   either. :) */
-			return 0;
-		}
+	if (is_power_of_2(mtd->writesize))
+		mtd->writesize_shift = ffs(mtd->writesize) - 1;
+	else
+		mtd->writesize_shift = 0;
+
+	mtd->erasesize_mask = (1 << mtd->erasesize_shift) - 1;
+	mtd->writesize_mask = (1 << mtd->writesize_shift) - 1;
+
+	/* Some chips always power up locked. Unlock them now */
+	if ((mtd->flags & MTD_WRITEABLE) && (mtd->flags & MTD_POWERUP_LOCK)) {
+		error = mtd_unlock(mtd, 0, mtd->size);
+		if (error && error != -EOPNOTSUPP)
+			printk(KERN_WARNING
+			       "%s: unlock failed, writes may not work\n",
+			       mtd->name);
+	}
+
+#ifndef __UBOOT__
+	/* Caller should have set dev.parent to match the
+	 * physical device.
+	 */
+	mtd->dev.type = &mtd_devtype;
+	mtd->dev.class = &mtd_class;
+	mtd->dev.devt = MTD_DEVT(i);
+	dev_set_name(&mtd->dev, "mtd%d", i);
+	dev_set_drvdata(&mtd->dev, mtd);
+	if (device_register(&mtd->dev) != 0)
+		goto fail_added;
 
+	if (MTD_DEVT(i))
+		device_create(&mtd_class, mtd->dev.parent,
+			      MTD_DEVT(i) + 1,
+			      NULL, "mtd%dro", i);
+
+	pr_debug("mtd: Giving out device %d to %s\n", i, mtd->name);
+	/* No need to get a refcount on the module containing
+	   the notifier, since we hold the mtd_table_mutex */
+	list_for_each_entry(not, &mtd_notifiers, list)
+		not->add(mtd);
+#endif
+
+	mutex_unlock(&mtd_table_mutex);
+	/* We _know_ we aren't being removed, because
+	   our caller is still holding us here. So none
+	   of this try_ nonsense, and no bitching about it
+	   either. :) */
+	__module_get(THIS_MODULE);
+	return 0;
+
+#ifndef __UBOOT__
+fail_added:
+	idr_remove(&mtd_idr, i);
+#endif
+fail_locked:
+	mutex_unlock(&mtd_table_mutex);
 	return 1;
 }
 
 /**
- *      del_mtd_device - unregister an MTD device
- *      @mtd: pointer to MTD device info structure
+ *	del_mtd_device - unregister an MTD device
+ *	@mtd: pointer to MTD device info structure
  *
- *      Remove a device from the list of MTD devices present in the system,
- *      and notify each currently active MTD 'user' of its departure.
- *      Returns zero on success or 1 on failure, which currently will happen
- *      if the requested device does not appear to be present in the list.
+ *	Remove a device from the list of MTD devices present in the system,
+ *	and notify each currently active MTD 'user' of its departure.
+ *	Returns zero on success or 1 on failure, which currently will happen
+ *	if the requested device does not appear to be present in the list.
  */
+
 int del_mtd_device(struct mtd_info *mtd)
 {
 	int ret;
+#ifndef __UBOOT__
+	struct mtd_notifier *not;
+#endif
+
+	mutex_lock(&mtd_table_mutex);
 
-	if (mtd_table[mtd->index] != mtd) {
+	if (idr_find(&mtd_idr, mtd->index) != mtd) {
 		ret = -ENODEV;
-	} else if (mtd->usecount) {
-		printk(KERN_NOTICE "Removing MTD device #%d (%s)"
-				" with use count %d\n",
-				mtd->index, mtd->name, mtd->usecount);
+		goto out_error;
+	}
+
+#ifndef __UBOOT__
+	/* No need to get a refcount on the module containing
+		the notifier, since we hold the mtd_table_mutex */
+	list_for_each_entry(not, &mtd_notifiers, list)
+		not->remove(mtd);
+#endif
+
+	if (mtd->usecount) {
+		printk(KERN_NOTICE "Removing MTD device #%d (%s) with use count %d\n",
+		       mtd->index, mtd->name, mtd->usecount);
 		ret = -EBUSY;
 	} else {
-		/* No need to get a refcount on the module containing
-		 * the notifier, since we hold the mtd_table_mutex */
-		mtd_table[mtd->index] = NULL;
+#ifndef __UBOOT__
+		device_unregister(&mtd->dev);
+#endif
+
+		idr_remove(&mtd_idr, mtd->index);
 
+		module_put(THIS_MODULE);
 		ret = 0;
 	}
 
+out_error:
+	mutex_unlock(&mtd_table_mutex);
 	return ret;
 }
 
+#ifndef __UBOOT__
+/**
+ * mtd_device_parse_register - parse partitions and register an MTD device.
+ *
+ * @mtd: the MTD device to register
+ * @types: the list of MTD partition probes to try, see
+ *         'parse_mtd_partitions()' for more information
+ * @parser_data: MTD partition parser-specific data
+ * @parts: fallback partition information to register, if parsing fails;
+ *         only valid if %nr_parts > %0
+ * @nr_parts: the number of partitions in parts, if zero then the full
+ *            MTD device is registered if no partition info is found
+ *
+ * This function aggregates MTD partitions parsing (done by
+ * 'parse_mtd_partitions()') and MTD device and partitions registering. It
+ * basically follows the most common pattern found in many MTD drivers:
+ *
+ * * It first tries to probe partitions on MTD device @mtd using parsers
+ *   specified in @types (if @types is %NULL, then the default list of parsers
+ *   is used, see 'parse_mtd_partitions()' for more information). If none are
+ *   found this functions tries to fallback to information specified in
+ *   @parts/@nr_parts.
+ * * If any partitioning info was found, this function registers the found
+ *   partitions.
+ * * If no partitions were found this function just registers the MTD device
+ *   @mtd and exits.
+ *
+ * Returns zero in case of success and a negative error code in case of failure.
+ */
+int mtd_device_parse_register(struct mtd_info *mtd, const char * const *types,
+			      struct mtd_part_parser_data *parser_data,
+			      const struct mtd_partition *parts,
+			      int nr_parts)
+{
+	int err;
+	struct mtd_partition *real_parts;
+
+	err = parse_mtd_partitions(mtd, types, &real_parts, parser_data);
+	if (err <= 0 && nr_parts && parts) {
+		real_parts = kmemdup(parts, sizeof(*parts) * nr_parts,
+				     GFP_KERNEL);
+		if (!real_parts)
+			err = -ENOMEM;
+		else
+			err = nr_parts;
+	}
+
+	if (err > 0) {
+		err = add_mtd_partitions(mtd, real_parts, err);
+		kfree(real_parts);
+	} else if (err == 0) {
+		err = add_mtd_device(mtd);
+		if (err == 1)
+			err = -ENODEV;
+	}
+
+	return err;
+}
+EXPORT_SYMBOL_GPL(mtd_device_parse_register);
+
+/**
+ * mtd_device_unregister - unregister an existing MTD device.
+ *
+ * @master: the MTD device to unregister.  This will unregister both the master
+ *          and any partitions if registered.
+ */
+int mtd_device_unregister(struct mtd_info *master)
+{
+	int err;
+
+	err = del_mtd_partitions(master);
+	if (err)
+		return err;
+
+	if (!device_is_registered(&master->dev))
+		return 0;
+
+	return del_mtd_device(master);
+}
+EXPORT_SYMBOL_GPL(mtd_device_unregister);
+
+/**
+ *	register_mtd_user - register a 'user' of MTD devices.
+ *	@new: pointer to notifier info structure
+ *
+ *	Registers a pair of callbacks function to be called upon addition
+ *	or removal of MTD devices. Causes the 'add' callback to be immediately
+ *	invoked for each MTD device currently present in the system.
+ */
+void register_mtd_user (struct mtd_notifier *new)
+{
+	struct mtd_info *mtd;
+
+	mutex_lock(&mtd_table_mutex);
+
+	list_add(&new->list, &mtd_notifiers);
+
+	__module_get(THIS_MODULE);
+
+	mtd_for_each_device(mtd)
+		new->add(mtd);
+
+	mutex_unlock(&mtd_table_mutex);
+}
+EXPORT_SYMBOL_GPL(register_mtd_user);
+
+/**
+ *	unregister_mtd_user - unregister a 'user' of MTD devices.
+ *	@old: pointer to notifier info structure
+ *
+ *	Removes a callback function pair from the list of 'users' to be
+ *	notified upon addition or removal of MTD devices. Causes the
+ *	'remove' callback to be immediately invoked for each MTD device
+ *	currently present in the system.
+ */
+int unregister_mtd_user (struct mtd_notifier *old)
+{
+	struct mtd_info *mtd;
+
+	mutex_lock(&mtd_table_mutex);
+
+	module_put(THIS_MODULE);
+
+	mtd_for_each_device(mtd)
+		old->remove(mtd);
+
+	list_del(&old->list);
+	mutex_unlock(&mtd_table_mutex);
+	return 0;
+}
+EXPORT_SYMBOL_GPL(unregister_mtd_user);
+#endif
+
 /**
  *	get_mtd_device - obtain a validated handle for an MTD device
  *	@mtd: last known address of the required MTD device
  *	@num: internal device number of the required MTD device
  *
  *	Given a number and NULL address, return the num'th entry in the device
- *      table, if any.  Given an address and num == -1, search the device table
- *      for a device with that address and return if it's still present. Given
- *      both, return the num'th driver only if its address matches. Return
- *      error code if not.
+ *	table, if any.	Given an address and num == -1, search the device table
+ *	for a device with that address and return if it's still present. Given
+ *	both, return the num'th driver only if its address matches. Return
+ *	error code if not.
  */
 struct mtd_info *get_mtd_device(struct mtd_info *mtd, int num)
 {
-	struct mtd_info *ret = NULL;
-	int i, err = -ENODEV;
+	struct mtd_info *ret = NULL, *other;
+	int err = -ENODEV;
+
+	mutex_lock(&mtd_table_mutex);
 
 	if (num == -1) {
-		for (i = 0; i < MAX_MTD_DEVICES; i++)
-			if (mtd_table[i] == mtd)
-				ret = mtd_table[i];
-	} else if (num < MAX_MTD_DEVICES) {
-		ret = mtd_table[num];
+		mtd_for_each_device(other) {
+			if (other == mtd) {
+				ret = mtd;
+				break;
+			}
+		}
+	} else if (num >= 0) {
+		ret = idr_find(&mtd_idr, num);
 		if (mtd && mtd != ret)
 			ret = NULL;
 	}
 
-	if (!ret)
-		goto out_unlock;
+	if (!ret) {
+		ret = ERR_PTR(err);
+		goto out;
+	}
 
-	ret->usecount++;
+	err = __get_mtd_device(ret);
+	if (err)
+		ret = ERR_PTR(err);
+out:
+	mutex_unlock(&mtd_table_mutex);
 	return ret;
+}
+EXPORT_SYMBOL_GPL(get_mtd_device);
 
-out_unlock:
-	return ERR_PTR(err);
+
+int __get_mtd_device(struct mtd_info *mtd)
+{
+	int err;
+
+	if (!try_module_get(mtd->owner))
+		return -ENODEV;
+
+	if (mtd->_get_device) {
+		err = mtd->_get_device(mtd);
+
+		if (err) {
+			module_put(mtd->owner);
+			return err;
+		}
+	}
+	mtd->usecount++;
+	return 0;
 }
+EXPORT_SYMBOL_GPL(__get_mtd_device);
 
 /**
- *      get_mtd_device_nm - obtain a validated handle for an MTD device by
- *      device name
- *      @name: MTD device name to open
+ *	get_mtd_device_nm - obtain a validated handle for an MTD device by
+ *	device name
+ *	@name: MTD device name to open
  *
- *      This function returns MTD device description structure in case of
- *      success and an error code in case of failure.
+ * 	This function returns MTD device description structure in case of
+ * 	success and an error code in case of failure.
  */
 struct mtd_info *get_mtd_device_nm(const char *name)
 {
-	int i, err = -ENODEV;
-	struct mtd_info *mtd = NULL;
+	int err = -ENODEV;
+	struct mtd_info *mtd = NULL, *other;
+
+	mutex_lock(&mtd_table_mutex);
 
-	for (i = 0; i < MAX_MTD_DEVICES; i++) {
-		if (mtd_table[i] && !strcmp(name, mtd_table[i]->name)) {
-			mtd = mtd_table[i];
+	mtd_for_each_device(other) {
+		if (!strcmp(name, other->name)) {
+			mtd = other;
 			break;
 		}
 	}
@@ -133,20 +770,18 @@ struct mtd_info *get_mtd_device_nm(const char *name)
 	if (!mtd)
 		goto out_unlock;
 
-	mtd->usecount++;
+	err = __get_mtd_device(mtd);
+	if (err)
+		goto out_unlock;
+
+	mutex_unlock(&mtd_table_mutex);
 	return mtd;
 
 out_unlock:
+	mutex_unlock(&mtd_table_mutex);
 	return ERR_PTR(err);
 }
-
-void put_mtd_device(struct mtd_info *mtd)
-{
-	int c;
-
-	c = --mtd->usecount;
-	BUG_ON(c < 0);
-}
+EXPORT_SYMBOL_GPL(get_mtd_device_nm);
 
 #if defined(CONFIG_CMD_MTDPARTS_SPREAD)
 /**
@@ -192,7 +827,28 @@ void mtd_get_len_incl_bad(struct mtd_info *mtd, uint64_t offset,
 }
 #endif /* defined(CONFIG_CMD_MTDPARTS_SPREAD) */
 
- /*
+void put_mtd_device(struct mtd_info *mtd)
+{
+	mutex_lock(&mtd_table_mutex);
+	__put_mtd_device(mtd);
+	mutex_unlock(&mtd_table_mutex);
+
+}
+EXPORT_SYMBOL_GPL(put_mtd_device);
+
+void __put_mtd_device(struct mtd_info *mtd)
+{
+	--mtd->usecount;
+	BUG_ON(mtd->usecount < 0);
+
+	if (mtd->_put_device)
+		mtd->_put_device(mtd);
+
+	module_put(mtd->owner);
+}
+EXPORT_SYMBOL_GPL(__put_mtd_device);
+
+/*
  * Erase is an asynchronous operation.  Device drivers are supposed
  * to call instr->callback() whenever the operation completes, even
  * if it completes with a failure.
@@ -213,11 +869,64 @@ int mtd_erase(struct mtd_info *mtd, struct erase_info *instr)
 	}
 	return mtd->_erase(mtd, instr);
 }
+EXPORT_SYMBOL_GPL(mtd_erase);
+
+#ifndef __UBOOT__
+/*
+ * This stuff for eXecute-In-Place. phys is optional and may be set to NULL.
+ */
+int mtd_point(struct mtd_info *mtd, loff_t from, size_t len, size_t *retlen,
+	      void **virt, resource_size_t *phys)
+{
+	*retlen = 0;
+	*virt = NULL;
+	if (phys)
+		*phys = 0;
+	if (!mtd->_point)
+		return -EOPNOTSUPP;
+	if (from < 0 || from > mtd->size || len > mtd->size - from)
+		return -EINVAL;
+	if (!len)
+		return 0;
+	return mtd->_point(mtd, from, len, retlen, virt, phys);
+}
+EXPORT_SYMBOL_GPL(mtd_point);
+
+/* We probably shouldn't allow XIP if the unpoint isn't a NULL */
+int mtd_unpoint(struct mtd_info *mtd, loff_t from, size_t len)
+{
+	if (!mtd->_point)
+		return -EOPNOTSUPP;
+	if (from < 0 || from > mtd->size || len > mtd->size - from)
+		return -EINVAL;
+	if (!len)
+		return 0;
+	return mtd->_unpoint(mtd, from, len);
+}
+EXPORT_SYMBOL_GPL(mtd_unpoint);
+#endif
+
+/*
+ * Allow NOMMU mmap() to directly map the device (if not NULL)
+ * - return the address to which the offset maps
+ * - return -ENOSYS to indicate refusal to do the mapping
+ */
+unsigned long mtd_get_unmapped_area(struct mtd_info *mtd, unsigned long len,
+				    unsigned long offset, unsigned long flags)
+{
+	if (!mtd->_get_unmapped_area)
+		return -EOPNOTSUPP;
+	if (offset > mtd->size || len > mtd->size - offset)
+		return -EINVAL;
+	return mtd->_get_unmapped_area(mtd, len, offset, flags);
+}
+EXPORT_SYMBOL_GPL(mtd_get_unmapped_area);
 
 int mtd_read(struct mtd_info *mtd, loff_t from, size_t len, size_t *retlen,
 	     u_char *buf)
 {
 	int ret_code;
+	*retlen = 0;
 	if (from < 0 || from > mtd->size || len > mtd->size - from)
 		return -EINVAL;
 	if (!len)
@@ -235,6 +944,7 @@ int mtd_read(struct mtd_info *mtd, loff_t from, size_t len, size_t *retlen,
 		return 0;	/* device lacks ecc */
 	return ret_code >= mtd->bitflip_threshold ? -EUCLEAN : 0;
 }
+EXPORT_SYMBOL_GPL(mtd_read);
 
 int mtd_write(struct mtd_info *mtd, loff_t to, size_t len, size_t *retlen,
 	      const u_char *buf)
@@ -248,6 +958,7 @@ int mtd_write(struct mtd_info *mtd, loff_t to, size_t len, size_t *retlen,
 		return 0;
 	return mtd->_write(mtd, to, len, retlen, buf);
 }
+EXPORT_SYMBOL_GPL(mtd_write);
 
 /*
  * In blackbox flight recorder like scenarios we want to make successful writes
@@ -270,14 +981,28 @@ int mtd_panic_write(struct mtd_info *mtd, loff_t to, size_t len, size_t *retlen,
 		return 0;
 	return mtd->_panic_write(mtd, to, len, retlen, buf);
 }
+EXPORT_SYMBOL_GPL(mtd_panic_write);
 
 int mtd_read_oob(struct mtd_info *mtd, loff_t from, struct mtd_oob_ops *ops)
 {
+	int ret_code;
 	ops->retlen = ops->oobretlen = 0;
 	if (!mtd->_read_oob)
 		return -EOPNOTSUPP;
-	return mtd->_read_oob(mtd, from, ops);
+	/*
+	 * In cases where ops->datbuf != NULL, mtd->_read_oob() has semantics
+	 * similar to mtd->_read(), returning a non-negative integer
+	 * representing max bitflips. In other cases, mtd->_read_oob() may
+	 * return -EUCLEAN. In all cases, perform similar logic to mtd_read().
+	 */
+	ret_code = mtd->_read_oob(mtd, from, ops);
+	if (unlikely(ret_code < 0))
+		return ret_code;
+	if (mtd->ecc_strength == 0)
+		return 0;	/* device lacks ecc */
+	return ret_code >= mtd->bitflip_threshold ? -EUCLEAN : 0;
 }
+EXPORT_SYMBOL_GPL(mtd_read_oob);
 
 /*
  * Method to access the protection register area, present in some flash
@@ -293,6 +1018,7 @@ int mtd_get_fact_prot_info(struct mtd_info *mtd, struct otp_info *buf,
 		return 0;
 	return mtd->_get_fact_prot_info(mtd, buf, len);
 }
+EXPORT_SYMBOL_GPL(mtd_get_fact_prot_info);
 
 int mtd_read_fact_prot_reg(struct mtd_info *mtd, loff_t from, size_t len,
 			   size_t *retlen, u_char *buf)
@@ -304,6 +1030,7 @@ int mtd_read_fact_prot_reg(struct mtd_info *mtd, loff_t from, size_t len,
 		return 0;
 	return mtd->_read_fact_prot_reg(mtd, from, len, retlen, buf);
 }
+EXPORT_SYMBOL_GPL(mtd_read_fact_prot_reg);
 
 int mtd_get_user_prot_info(struct mtd_info *mtd, struct otp_info *buf,
 			   size_t len)
@@ -314,6 +1041,7 @@ int mtd_get_user_prot_info(struct mtd_info *mtd, struct otp_info *buf,
 		return 0;
 	return mtd->_get_user_prot_info(mtd, buf, len);
 }
+EXPORT_SYMBOL_GPL(mtd_get_user_prot_info);
 
 int mtd_read_user_prot_reg(struct mtd_info *mtd, loff_t from, size_t len,
 			   size_t *retlen, u_char *buf)
@@ -325,6 +1053,7 @@ int mtd_read_user_prot_reg(struct mtd_info *mtd, loff_t from, size_t len,
 		return 0;
 	return mtd->_read_user_prot_reg(mtd, from, len, retlen, buf);
 }
+EXPORT_SYMBOL_GPL(mtd_read_user_prot_reg);
 
 int mtd_write_user_prot_reg(struct mtd_info *mtd, loff_t to, size_t len,
 			    size_t *retlen, u_char *buf)
@@ -336,6 +1065,7 @@ int mtd_write_user_prot_reg(struct mtd_info *mtd, loff_t to, size_t len,
 		return 0;
 	return mtd->_write_user_prot_reg(mtd, to, len, retlen, buf);
 }
+EXPORT_SYMBOL_GPL(mtd_write_user_prot_reg);
 
 int mtd_lock_user_prot_reg(struct mtd_info *mtd, loff_t from, size_t len)
 {
@@ -345,6 +1075,7 @@ int mtd_lock_user_prot_reg(struct mtd_info *mtd, loff_t from, size_t len)
 		return 0;
 	return mtd->_lock_user_prot_reg(mtd, from, len);
 }
+EXPORT_SYMBOL_GPL(mtd_lock_user_prot_reg);
 
 /* Chip-supported device locking */
 int mtd_lock(struct mtd_info *mtd, loff_t ofs, uint64_t len)
@@ -357,6 +1088,7 @@ int mtd_lock(struct mtd_info *mtd, loff_t ofs, uint64_t len)
 		return 0;
 	return mtd->_lock(mtd, ofs, len);
 }
+EXPORT_SYMBOL_GPL(mtd_lock);
 
 int mtd_unlock(struct mtd_info *mtd, loff_t ofs, uint64_t len)
 {
@@ -368,6 +1100,19 @@ int mtd_unlock(struct mtd_info *mtd, loff_t ofs, uint64_t len)
 		return 0;
 	return mtd->_unlock(mtd, ofs, len);
 }
+EXPORT_SYMBOL_GPL(mtd_unlock);
+
+int mtd_is_locked(struct mtd_info *mtd, loff_t ofs, uint64_t len)
+{
+	if (!mtd->_is_locked)
+		return -EOPNOTSUPP;
+	if (ofs < 0 || ofs > mtd->size || len > mtd->size - ofs)
+		return -EINVAL;
+	if (!len)
+		return 0;
+	return mtd->_is_locked(mtd, ofs, len);
+}
+EXPORT_SYMBOL_GPL(mtd_is_locked);
 
 int mtd_block_isbad(struct mtd_info *mtd, loff_t ofs)
 {
@@ -377,6 +1122,7 @@ int mtd_block_isbad(struct mtd_info *mtd, loff_t ofs)
 		return -EINVAL;
 	return mtd->_block_isbad(mtd, ofs);
 }
+EXPORT_SYMBOL_GPL(mtd_block_isbad);
 
 int mtd_block_markbad(struct mtd_info *mtd, loff_t ofs)
 {
@@ -388,3 +1134,225 @@ int mtd_block_markbad(struct mtd_info *mtd, loff_t ofs)
 		return -EROFS;
 	return mtd->_block_markbad(mtd, ofs);
 }
+EXPORT_SYMBOL_GPL(mtd_block_markbad);
+
+#ifndef __UBOOT__
+/*
+ * default_mtd_writev - the default writev method
+ * @mtd: mtd device description object pointer
+ * @vecs: the vectors to write
+ * @count: count of vectors in @vecs
+ * @to: the MTD device offset to write to
+ * @retlen: on exit contains the count of bytes written to the MTD device.
+ *
+ * This function returns zero in case of success and a negative error code in
+ * case of failure.
+ */
+static int default_mtd_writev(struct mtd_info *mtd, const struct kvec *vecs,
+			      unsigned long count, loff_t to, size_t *retlen)
+{
+	unsigned long i;
+	size_t totlen = 0, thislen;
+	int ret = 0;
+
+	for (i = 0; i < count; i++) {
+		if (!vecs[i].iov_len)
+			continue;
+		ret = mtd_write(mtd, to, vecs[i].iov_len, &thislen,
+				vecs[i].iov_base);
+		totlen += thislen;
+		if (ret || thislen != vecs[i].iov_len)
+			break;
+		to += vecs[i].iov_len;
+	}
+	*retlen = totlen;
+	return ret;
+}
+
+/*
+ * mtd_writev - the vector-based MTD write method
+ * @mtd: mtd device description object pointer
+ * @vecs: the vectors to write
+ * @count: count of vectors in @vecs
+ * @to: the MTD device offset to write to
+ * @retlen: on exit contains the count of bytes written to the MTD device.
+ *
+ * This function returns zero in case of success and a negative error code in
+ * case of failure.
+ */
+int mtd_writev(struct mtd_info *mtd, const struct kvec *vecs,
+	       unsigned long count, loff_t to, size_t *retlen)
+{
+	*retlen = 0;
+	if (!(mtd->flags & MTD_WRITEABLE))
+		return -EROFS;
+	if (!mtd->_writev)
+		return default_mtd_writev(mtd, vecs, count, to, retlen);
+	return mtd->_writev(mtd, vecs, count, to, retlen);
+}
+EXPORT_SYMBOL_GPL(mtd_writev);
+
+/**
+ * mtd_kmalloc_up_to - allocate a contiguous buffer up to the specified size
+ * @mtd: mtd device description object pointer
+ * @size: a pointer to the ideal or maximum size of the allocation, points
+ *        to the actual allocation size on success.
+ *
+ * This routine attempts to allocate a contiguous kernel buffer up to
+ * the specified size, backing off the size of the request exponentially
+ * until the request succeeds or until the allocation size falls below
+ * the system page size. This attempts to make sure it does not adversely
+ * impact system performance, so when allocating more than one page, we
+ * ask the memory allocator to avoid re-trying, swapping, writing back
+ * or performing I/O.
+ *
+ * Note, this function also makes sure that the allocated buffer is aligned to
+ * the MTD device's min. I/O unit, i.e. the "mtd->writesize" value.
+ *
+ * This is called, for example by mtd_{read,write} and jffs2_scan_medium,
+ * to handle smaller (i.e. degraded) buffer allocations under low- or
+ * fragmented-memory situations where such reduced allocations, from a
+ * requested ideal, are allowed.
+ *
+ * Returns a pointer to the allocated buffer on success; otherwise, NULL.
+ */
+void *mtd_kmalloc_up_to(const struct mtd_info *mtd, size_t *size)
+{
+	gfp_t flags = __GFP_NOWARN | __GFP_WAIT |
+		       __GFP_NORETRY | __GFP_NO_KSWAPD;
+	size_t min_alloc = max_t(size_t, mtd->writesize, PAGE_SIZE);
+	void *kbuf;
+
+	*size = min_t(size_t, *size, KMALLOC_MAX_SIZE);
+
+	while (*size > min_alloc) {
+		kbuf = kmalloc(*size, flags);
+		if (kbuf)
+			return kbuf;
+
+		*size >>= 1;
+		*size = ALIGN(*size, mtd->writesize);
+	}
+
+	/*
+	 * For the last resort allocation allow 'kmalloc()' to do all sorts of
+	 * things (write-back, dropping caches, etc) by using GFP_KERNEL.
+	 */
+	return kmalloc(*size, GFP_KERNEL);
+}
+EXPORT_SYMBOL_GPL(mtd_kmalloc_up_to);
+#endif
+
+#ifdef CONFIG_PROC_FS
+
+/*====================================================================*/
+/* Support for /proc/mtd */
+
+static int mtd_proc_show(struct seq_file *m, void *v)
+{
+	struct mtd_info *mtd;
+
+	seq_puts(m, "dev:    size   erasesize  name\n");
+	mutex_lock(&mtd_table_mutex);
+	mtd_for_each_device(mtd) {
+		seq_printf(m, "mtd%d: %8.8llx %8.8x \"%s\"\n",
+			   mtd->index, (unsigned long long)mtd->size,
+			   mtd->erasesize, mtd->name);
+	}
+	mutex_unlock(&mtd_table_mutex);
+	return 0;
+}
+
+static int mtd_proc_open(struct inode *inode, struct file *file)
+{
+	return single_open(file, mtd_proc_show, NULL);
+}
+
+static const struct file_operations mtd_proc_ops = {
+	.open		= mtd_proc_open,
+	.read		= seq_read,
+	.llseek		= seq_lseek,
+	.release	= single_release,
+};
+#endif /* CONFIG_PROC_FS */
+
+/*====================================================================*/
+/* Init code */
+
+#ifndef __UBOOT__
+static int __init mtd_bdi_init(struct backing_dev_info *bdi, const char *name)
+{
+	int ret;
+
+	ret = bdi_init(bdi);
+	if (!ret)
+		ret = bdi_register(bdi, NULL, "%s", name);
+
+	if (ret)
+		bdi_destroy(bdi);
+
+	return ret;
+}
+
+static struct proc_dir_entry *proc_mtd;
+
+static int __init init_mtd(void)
+{
+	int ret;
+
+	ret = class_register(&mtd_class);
+	if (ret)
+		goto err_reg;
+
+	ret = mtd_bdi_init(&mtd_bdi_unmappable, "mtd-unmap");
+	if (ret)
+		goto err_bdi1;
+
+	ret = mtd_bdi_init(&mtd_bdi_ro_mappable, "mtd-romap");
+	if (ret)
+		goto err_bdi2;
+
+	ret = mtd_bdi_init(&mtd_bdi_rw_mappable, "mtd-rwmap");
+	if (ret)
+		goto err_bdi3;
+
+	proc_mtd = proc_create("mtd", 0, NULL, &mtd_proc_ops);
+
+	ret = init_mtdchar();
+	if (ret)
+		goto out_procfs;
+
+	return 0;
+
+out_procfs:
+	if (proc_mtd)
+		remove_proc_entry("mtd", NULL);
+err_bdi3:
+	bdi_destroy(&mtd_bdi_ro_mappable);
+err_bdi2:
+	bdi_destroy(&mtd_bdi_unmappable);
+err_bdi1:
+	class_unregister(&mtd_class);
+err_reg:
+	pr_err("Error registering mtd class or bdi: %d\n", ret);
+	return ret;
+}
+
+static void __exit cleanup_mtd(void)
+{
+	cleanup_mtdchar();
+	if (proc_mtd)
+		remove_proc_entry("mtd", NULL);
+	class_unregister(&mtd_class);
+	bdi_destroy(&mtd_bdi_unmappable);
+	bdi_destroy(&mtd_bdi_ro_mappable);
+	bdi_destroy(&mtd_bdi_rw_mappable);
+}
+
+module_init(init_mtd);
+module_exit(cleanup_mtd);
+#endif
+
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("David Woodhouse <dwmw2@infradead.org>");
+MODULE_DESCRIPTION("Core MTD registration and access routines");