mtdcore.c 45.8 KB
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/*
 * Core registration and callback routines for MTD
 * drivers and users.
 *
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 * Copyright © 1999-2010 David Woodhouse <dwmw2@infradead.org>
 * Copyright © 2006      Red Hat UK Limited 
 *
 * 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
 *
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 */

#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/ptrace.h>
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#include <linux/seq_file.h>
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#include <linux/string.h>
#include <linux/timer.h>
#include <linux/major.h>
#include <linux/fs.h>
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#include <linux/err.h>
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#include <linux/ioctl.h>
#include <linux/init.h>
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#include <linux/of.h>
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#include <linux/proc_fs.h>
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#include <linux/idr.h>
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#include <linux/backing-dev.h>
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#include <linux/gfp.h>
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#include <linux/slab.h>
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#include <linux/reboot.h>
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#include <linux/kconfig.h>
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#include <linux/leds.h>
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#include <linux/mtd/mtd.h>
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#include <linux/mtd/partitions.h>
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#include "mtdcore.h"
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static struct backing_dev_info mtd_bdi = {
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};
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#ifdef CONFIG_PM_SLEEP

static int mtd_cls_suspend(struct device *dev)
{
	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 SIMPLE_DEV_PM_OPS(mtd_cls_pm_ops, mtd_cls_suspend, mtd_cls_resume);
#define MTD_CLS_PM_OPS (&mtd_cls_pm_ops)
#else
#define MTD_CLS_PM_OPS NULL
#endif
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static struct class mtd_class = {
	.name = "mtd",
	.owner = THIS_MODULE,
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	.pm = MTD_CLS_PM_OPS,
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};
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static DEFINE_IDR(mtd_idr);

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/* These are exported solely for the purpose of mtd_blkdevs.c. You
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   should not use them for _anything_ else */
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DEFINE_MUTEX(mtd_table_mutex);
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EXPORT_SYMBOL_GPL(mtd_table_mutex);
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struct mtd_info *__mtd_next_device(int i)
{
	return idr_get_next(&mtd_idr, &i);
}
EXPORT_SYMBOL_GPL(__mtd_next_device);
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static LIST_HEAD(mtd_notifiers);

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#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)
{
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	struct mtd_info *mtd = dev_get_drvdata(dev);
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	dev_t index = MTD_DEVT(mtd->index);
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	/* remove /dev/mtdXro node */
	device_destroy(&mtd_class, index + 1);
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}

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static ssize_t mtd_type_show(struct device *dev,
		struct device_attribute *attr, char *buf)
{
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	struct mtd_info *mtd = dev_get_drvdata(dev);
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	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;
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	case MTD_MLCNANDFLASH:
		type = "mlc-nand";
		break;
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	default:
		type = "unknown";
	}

	return snprintf(buf, PAGE_SIZE, "%s\n", type);
}
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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)
{
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	struct mtd_info *mtd = dev_get_drvdata(dev);
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	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)
{
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	struct mtd_info *mtd = dev_get_drvdata(dev);
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	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)
{
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	struct mtd_info *mtd = dev_get_drvdata(dev);
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	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)
{
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	struct mtd_info *mtd = dev_get_drvdata(dev);
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	return snprintf(buf, PAGE_SIZE, "%lu\n", (unsigned long)mtd->writesize);

}
static DEVICE_ATTR(writesize, S_IRUGO, mtd_writesize_show, NULL);

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static ssize_t mtd_subpagesize_show(struct device *dev,
		struct device_attribute *attr, char *buf)
{
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	struct mtd_info *mtd = dev_get_drvdata(dev);
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	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);

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static ssize_t mtd_oobsize_show(struct device *dev,
		struct device_attribute *attr, char *buf)
{
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	struct mtd_info *mtd = dev_get_drvdata(dev);
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	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)
{
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	struct mtd_info *mtd = dev_get_drvdata(dev);
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	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)
{
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	struct mtd_info *mtd = dev_get_drvdata(dev);
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	return snprintf(buf, PAGE_SIZE, "%s\n", mtd->name);

}
static DEVICE_ATTR(name, S_IRUGO, mtd_name_show, NULL);
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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);

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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);

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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);

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static ssize_t mtd_ecc_stats_corrected_show(struct device *dev,
		struct device_attribute *attr, char *buf)
{
	struct mtd_info *mtd = dev_get_drvdata(dev);
	struct mtd_ecc_stats *ecc_stats = &mtd->ecc_stats;

	return snprintf(buf, PAGE_SIZE, "%u\n", ecc_stats->corrected);
}
static DEVICE_ATTR(corrected_bits, S_IRUGO,
		   mtd_ecc_stats_corrected_show, NULL);

static ssize_t mtd_ecc_stats_errors_show(struct device *dev,
		struct device_attribute *attr, char *buf)
{
	struct mtd_info *mtd = dev_get_drvdata(dev);
	struct mtd_ecc_stats *ecc_stats = &mtd->ecc_stats;

	return snprintf(buf, PAGE_SIZE, "%u\n", ecc_stats->failed);
}
static DEVICE_ATTR(ecc_failures, S_IRUGO, mtd_ecc_stats_errors_show, NULL);

static ssize_t mtd_badblocks_show(struct device *dev,
		struct device_attribute *attr, char *buf)
{
	struct mtd_info *mtd = dev_get_drvdata(dev);
	struct mtd_ecc_stats *ecc_stats = &mtd->ecc_stats;

	return snprintf(buf, PAGE_SIZE, "%u\n", ecc_stats->badblocks);
}
static DEVICE_ATTR(bad_blocks, S_IRUGO, mtd_badblocks_show, NULL);

static ssize_t mtd_bbtblocks_show(struct device *dev,
		struct device_attribute *attr, char *buf)
{
	struct mtd_info *mtd = dev_get_drvdata(dev);
	struct mtd_ecc_stats *ecc_stats = &mtd->ecc_stats;

	return snprintf(buf, PAGE_SIZE, "%u\n", ecc_stats->bbtblocks);
}
static DEVICE_ATTR(bbt_blocks, S_IRUGO, mtd_bbtblocks_show, NULL);

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static struct attribute *mtd_attrs[] = {
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	&dev_attr_type.attr,
	&dev_attr_flags.attr,
	&dev_attr_size.attr,
	&dev_attr_erasesize.attr,
	&dev_attr_writesize.attr,
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	&dev_attr_subpagesize.attr,
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	&dev_attr_oobsize.attr,
	&dev_attr_numeraseregions.attr,
	&dev_attr_name.attr,
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	&dev_attr_ecc_strength.attr,
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	&dev_attr_ecc_step_size.attr,
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	&dev_attr_corrected_bits.attr,
	&dev_attr_ecc_failures.attr,
	&dev_attr_bad_blocks.attr,
	&dev_attr_bbt_blocks.attr,
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	&dev_attr_bitflip_threshold.attr,
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	NULL,
};
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ATTRIBUTE_GROUPS(mtd);
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static struct device_type mtd_devtype = {
	.name		= "mtd",
	.groups		= mtd_groups,
	.release	= mtd_release,
};

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#ifndef CONFIG_MMU
unsigned mtd_mmap_capabilities(struct mtd_info *mtd)
{
	switch (mtd->type) {
	case MTD_RAM:
		return NOMMU_MAP_COPY | NOMMU_MAP_DIRECT | NOMMU_MAP_EXEC |
			NOMMU_MAP_READ | NOMMU_MAP_WRITE;
	case MTD_ROM:
		return NOMMU_MAP_COPY | NOMMU_MAP_DIRECT | NOMMU_MAP_EXEC |
			NOMMU_MAP_READ;
	default:
		return NOMMU_MAP_COPY;
	}
}
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EXPORT_SYMBOL_GPL(mtd_mmap_capabilities);
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#endif

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static int mtd_reboot_notifier(struct notifier_block *n, unsigned long state,
			       void *cmd)
{
	struct mtd_info *mtd;

	mtd = container_of(n, struct mtd_info, reboot_notifier);
	mtd->_reboot(mtd);

	return NOTIFY_DONE;
}

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/**
 *	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
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 *	zero on success or non-zero on failure.
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 */

int add_mtd_device(struct mtd_info *mtd)
{
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	struct mtd_notifier *not;
	int i, error;
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	/*
	 * May occur, for instance, on buggy drivers which call
	 * mtd_device_parse_register() multiple times on the same master MTD,
	 * especially with CONFIG_MTD_PARTITIONED_MASTER=y.
	 */
	if (WARN_ONCE(mtd->backing_dev_info, "MTD already registered\n"))
		return -EEXIST;

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	mtd->backing_dev_info = &mtd_bdi;
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	BUG_ON(mtd->writesize == 0);
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	mutex_lock(&mtd_table_mutex);
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	i = idr_alloc(&mtd_idr, mtd, 0, 0, GFP_KERNEL);
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	if (i < 0) {
		error = i;
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		goto fail_locked;
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	}
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	mtd->index = i;
	mtd->usecount = 0;

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	/* default value if not set by driver */
	if (mtd->bitflip_threshold == 0)
		mtd->bitflip_threshold = mtd->ecc_strength;

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	if (is_power_of_2(mtd->erasesize))
		mtd->erasesize_shift = ffs(mtd->erasesize) - 1;
	else
		mtd->erasesize_shift = 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 */
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	if ((mtd->flags & MTD_WRITEABLE) && (mtd->flags & MTD_POWERUP_LOCK)) {
		error = mtd_unlock(mtd, 0, mtd->size);
		if (error && error != -EOPNOTSUPP)
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			printk(KERN_WARNING
			       "%s: unlock failed, writes may not work\n",
			       mtd->name);
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		/* Ignore unlock failures? */
		error = 0;
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	}

	/* Caller should have set dev.parent to match the
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	 * physical device, if appropriate.
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	 */
	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);
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	of_node_get(mtd_get_of_node(mtd));
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	error = device_register(&mtd->dev);
	if (error)
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		goto fail_added;

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	device_create(&mtd_class, mtd->dev.parent, MTD_DEVT(i) + 1, NULL,
		      "mtd%dro", i);
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	pr_debug("mtd: Giving out device %d to %s\n", i, mtd->name);
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	/* 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);

	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;
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fail_added:
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	of_node_put(mtd_get_of_node(mtd));
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	idr_remove(&mtd_idr, i);
fail_locked:
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	mutex_unlock(&mtd_table_mutex);
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	return error;
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}

/**
 *	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.
 */

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int del_mtd_device(struct mtd_info *mtd)
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{
	int ret;
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	struct mtd_notifier *not;
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	mutex_lock(&mtd_table_mutex);
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	if (idr_find(&mtd_idr, mtd->index) != mtd) {
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		ret = -ENODEV;
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		goto out_error;
	}

	/* 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);

	if (mtd->usecount) {
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		printk(KERN_NOTICE "Removing MTD device #%d (%s) with use count %d\n",
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		       mtd->index, mtd->name, mtd->usecount);
		ret = -EBUSY;
	} else {
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		device_unregister(&mtd->dev);

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		idr_remove(&mtd_idr, mtd->index);
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		of_node_put(mtd_get_of_node(mtd));
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		module_put(THIS_MODULE);
		ret = 0;
	}

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out_error:
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	mutex_unlock(&mtd_table_mutex);
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	return ret;
}

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static int mtd_add_device_partitions(struct mtd_info *mtd,
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				     struct mtd_partitions *parts)
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{
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	const struct mtd_partition *real_parts = parts->parts;
	int nbparts = parts->nr_parts;
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	int ret;

	if (nbparts == 0 || IS_ENABLED(CONFIG_MTD_PARTITIONED_MASTER)) {
		ret = add_mtd_device(mtd);
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		if (ret)
			return ret;
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	}

	if (nbparts > 0) {
		ret = add_mtd_partitions(mtd, real_parts, nbparts);
		if (ret && IS_ENABLED(CONFIG_MTD_PARTITIONED_MASTER))
			del_mtd_device(mtd);
		return ret;
	}

	return 0;
}

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/*
 * Set a few defaults based on the parent devices, if not provided by the
 * driver
 */
static void mtd_set_dev_defaults(struct mtd_info *mtd)
{
	if (mtd->dev.parent) {
		if (!mtd->owner && mtd->dev.parent->driver)
			mtd->owner = mtd->dev.parent->driver->owner;
		if (!mtd->name)
			mtd->name = dev_name(mtd->dev.parent);
	} else {
		pr_debug("mtd device won't show a device symlink in sysfs\n");
	}
}
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/**
 * 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
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 * @parser_data: MTD partition parser-specific data
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 * @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.
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 * * If any partitioning info was found, this function registers the found
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 *   partitions. If the MTD_PARTITIONED_MASTER option is set, then the device
 *   as a whole is registered first.
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 * * 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.
 */
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int mtd_device_parse_register(struct mtd_info *mtd, const char * const *types,
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			      struct mtd_part_parser_data *parser_data,
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			      const struct mtd_partition *parts,
			      int nr_parts)
{
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	struct mtd_partitions parsed;
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	int ret;
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	mtd_set_dev_defaults(mtd);

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	memset(&parsed, 0, sizeof(parsed));

	ret = parse_mtd_partitions(mtd, types, &parsed, parser_data);
	if ((ret < 0 || parsed.nr_parts == 0) && parts && nr_parts) {
		/* Fall back to driver-provided partitions */
		parsed = (struct mtd_partitions){
			.parts		= parts,
			.nr_parts	= nr_parts,
		};
	} else if (ret < 0) {
		/* Didn't come up with parsed OR fallback partitions */
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		pr_info("mtd: failed to find partitions; one or more parsers reports errors (%d)\n",
			ret);
		/* Don't abort on errors; we can still use unpartitioned MTD */
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		memset(&parsed, 0, sizeof(parsed));
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	}
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	ret = mtd_add_device_partitions(mtd, &parsed);
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	if (ret)
		goto out;
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	/*
	 * FIXME: some drivers unfortunately call this function more than once.
	 * So we have to check if we've already assigned the reboot notifier.
	 *
	 * Generally, we can make multiple calls work for most cases, but it
	 * does cause problems with parse_mtd_partitions() above (e.g.,
	 * cmdlineparts will register partitions more than once).
	 */
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	WARN_ONCE(mtd->_reboot && mtd->reboot_notifier.notifier_call,
		  "MTD already registered\n");
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	if (mtd->_reboot && !mtd->reboot_notifier.notifier_call) {
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		mtd->reboot_notifier.notifier_call = mtd_reboot_notifier;
		register_reboot_notifier(&mtd->reboot_notifier);
	}

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out:
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	/* Cleanup any parsed partitions */
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	mtd_part_parser_cleanup(&parsed);
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	return ret;
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}
EXPORT_SYMBOL_GPL(mtd_device_parse_register);

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/**
 * 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;

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	if (master->_reboot)
		unregister_reboot_notifier(&master->reboot_notifier);

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	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);

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/**
 *	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)
{
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	struct mtd_info *mtd;
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	mutex_lock(&mtd_table_mutex);
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	list_add(&new->list, &mtd_notifiers);

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	__module_get(THIS_MODULE);
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	mtd_for_each_device(mtd)
		new->add(mtd);
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	mutex_unlock(&mtd_table_mutex);
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}
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EXPORT_SYMBOL_GPL(register_mtd_user);
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/**
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 *	unregister_mtd_user - unregister a 'user' of MTD devices.
 *	@old: pointer to notifier info structure
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 *
 *	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)
{
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	struct mtd_info *mtd;
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	mutex_lock(&mtd_table_mutex);
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	module_put(THIS_MODULE);

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	mtd_for_each_device(mtd)
		old->remove(mtd);
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	list_del(&old->list);
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	mutex_unlock(&mtd_table_mutex);
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	return 0;
}
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EXPORT_SYMBOL_GPL(unregister_mtd_user);
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/**
 *	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
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 *	both, return the num'th driver only if its address matches. Return
 *	error code if not.
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 */
struct mtd_info *get_mtd_device(struct mtd_info *mtd, int num)
{
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	struct mtd_info *ret = NULL, *other;
	int err = -ENODEV;
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	mutex_lock(&mtd_table_mutex);
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	if (num == -1) {
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		mtd_for_each_device(other) {
			if (other == mtd) {
				ret = mtd;
				break;
			}
		}
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	} else if (num >= 0) {
		ret = idr_find(&mtd_idr, num);
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		if (mtd && mtd != ret)
			ret = NULL;
	}

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	if (!ret) {
		ret = ERR_PTR(err);
		goto out;
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	}
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	err = __get_mtd_device(ret);
	if (err)
		ret = ERR_PTR(err);
out:
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	mutex_unlock(&mtd_table_mutex);
	return ret;
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}
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EXPORT_SYMBOL_GPL(get_mtd_device);
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int __get_mtd_device(struct mtd_info *mtd)
{
	int err;

	if (!try_module_get(mtd->owner))
		return -ENODEV;

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	if (mtd->_get_device) {
		err = mtd->_get_device(mtd);
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		if (err) {
			module_put(mtd->owner);
			return err;
		}
	}
	mtd->usecount++;
	return 0;
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}
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EXPORT_SYMBOL_GPL(__get_mtd_device);
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/**
 *	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.
 */
struct mtd_info *get_mtd_device_nm(const char *name)
{
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	int err = -ENODEV;
	struct mtd_info *mtd = NULL, *other;
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	mutex_lock(&mtd_table_mutex);

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	mtd_for_each_device(other) {
		if (!strcmp(name, other->name)) {
			mtd = other;
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			break;
		}
	}

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	if (!mtd)
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		goto out_unlock;

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	err = __get_mtd_device(mtd);
	if (err)
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		goto out_unlock;

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	mutex_unlock(&mtd_table_mutex);
	return mtd;
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out_unlock:
	mutex_unlock(&mtd_table_mutex);
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	return ERR_PTR(err);
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}
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EXPORT_SYMBOL_GPL(get_mtd_device_nm);
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void put_mtd_device(struct mtd_info *mtd)
{
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	mutex_lock(&mtd_table_mutex);
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	__put_mtd_device(mtd);
	mutex_unlock(&mtd_table_mutex);

}
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EXPORT_SYMBOL_GPL(put_mtd_device);
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void __put_mtd_device(struct mtd_info *mtd)
{
	--mtd->usecount;
	BUG_ON(mtd->usecount < 0);

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	if (mtd->_put_device)
		mtd->_put_device(mtd);
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	module_put(mtd->owner);
}
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EXPORT_SYMBOL_GPL(__put_mtd_device);
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/*
 * Erase is an asynchronous operation.  Device drivers are supposed
 * to call instr->callback() whenever the operation completes, even
 * if it completes with a failure.
 * Callers are supposed to pass a callback function and wait for it
 * to be called before writing to the block.
 */
int mtd_erase(struct mtd_info *mtd, struct erase_info *instr)
{
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	if (instr->addr >= mtd->size || instr->len > mtd->size - instr->addr)
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		return -EINVAL;
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	if (!(mtd->flags & MTD_WRITEABLE))
		return -EROFS;
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	instr->fail_addr = MTD_FAIL_ADDR_UNKNOWN;
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	if (!instr->len) {
		instr->state = MTD_ERASE_DONE;
		mtd_erase_callback(instr);
		return 0;
	}
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	ledtrig_mtd_activity();
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	return mtd->_erase(mtd, instr);
}
EXPORT_SYMBOL_GPL(mtd_erase);

/*
 * 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;
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	*virt = NULL;
	if (phys)
		*phys = 0;
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	if (!mtd->_point)
		return -EOPNOTSUPP;
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	if (from < 0 || from >= mtd->size || len > mtd->size - from)
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		return -EINVAL;
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	if (!len)
		return 0;
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	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;
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	if (from < 0 || from >= mtd->size || len > mtd->size - from)
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		return -EINVAL;
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	if (!len)
		return 0;
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	return mtd->_unpoint(mtd, from, len);
}
EXPORT_SYMBOL_GPL(mtd_unpoint);

/*
 * 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;
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	if (offset >= mtd->size || len > mtd->size - offset)
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		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)
{
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	int ret_code;
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	*retlen = 0;
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	if (from < 0 || from >= mtd->size || len > mtd->size - from)
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		return -EINVAL;
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	if (!len)
		return 0;
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	ledtrig_mtd_activity();
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	/*
	 * In the absence of an error, drivers return a non-negative integer
	 * representing the maximum number of bitflips that were corrected on
	 * any one ecc region (if applicable; zero otherwise).
	 */
	ret_code = mtd->_read(mtd, from, len, retlen, buf);
	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;
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}
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)
{
	*retlen = 0;
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	if (to < 0 || to >= mtd->size || len > mtd->size - to)
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		return -EINVAL;
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	if (!mtd->_write || !(mtd->flags & MTD_WRITEABLE))
		return -EROFS;
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	if (!len)
		return 0;
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	ledtrig_mtd_activity();
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	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
 * in interrupt context. panic_write() is only intended to be called when its
 * known the kernel is about to panic and we need the write to succeed. Since
 * the kernel is not going to be running for much longer, this function can
 * break locks and delay to ensure the write succeeds (but not sleep).
 */
int mtd_panic_write(struct mtd_info *mtd, loff_t to, size_t len, size_t *retlen,
		    const u_char *buf)
{
	*retlen = 0;
	if (!mtd->_panic_write)
		return -EOPNOTSUPP;
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	if (to < 0 || to >= mtd->size || len > mtd->size - to)
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		return -EINVAL;
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	if (!(mtd->flags & MTD_WRITEABLE))
		return -EROFS;
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	if (!len)
		return 0;
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	return mtd->_panic_write(mtd, to, len, retlen, buf);
}
EXPORT_SYMBOL_GPL(mtd_panic_write);

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int mtd_read_oob(struct mtd_info *mtd, loff_t from, struct mtd_oob_ops *ops)
{
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	int ret_code;
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	ops->retlen = ops->oobretlen = 0;
	if (!mtd->_read_oob)
		return -EOPNOTSUPP;
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	ledtrig_mtd_activity();
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	/*
	 * 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;
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}
EXPORT_SYMBOL_GPL(mtd_read_oob);

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int mtd_write_oob(struct mtd_info *mtd, loff_t to,
				struct mtd_oob_ops *ops)
{
	ops->retlen = ops->oobretlen = 0;
	if (!mtd->_write_oob)
		return -EOPNOTSUPP;
	if (!(mtd->flags & MTD_WRITEABLE))
		return -EROFS;
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	ledtrig_mtd_activity();
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	return mtd->_write_oob(mtd, to, ops);
}
EXPORT_SYMBOL_GPL(mtd_write_oob);

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/**
 * mtd_ooblayout_ecc - Get the OOB region definition of a specific ECC section
 * @mtd: MTD device structure
 * @section: ECC section. Depending on the layout you may have all the ECC
 *	     bytes stored in a single contiguous section, or one section
 *	     per ECC chunk (and sometime several sections for a single ECC
 *	     ECC chunk)
 * @oobecc: OOB region struct filled with the appropriate ECC position
 *	    information
 *
 * This functions return ECC section information in the OOB area. I you want
 * to get all the ECC bytes information, then you should call
 * mtd_ooblayout_ecc(mtd, section++, oobecc) until it returns -ERANGE.
 *
 * Returns zero on success, a negative error code otherwise.
 */
int mtd_ooblayout_ecc(struct mtd_info *mtd, int section,
		      struct mtd_oob_region *oobecc)
{
	memset(oobecc, 0, sizeof(*oobecc));

	if (!mtd || section < 0)
		return -EINVAL;

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	if (!mtd->ooblayout || !mtd->ooblayout->ecc)
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		return -ENOTSUPP;

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	return mtd->ooblayout->ecc(mtd, section, oobecc);
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}
EXPORT_SYMBOL_GPL(mtd_ooblayout_ecc);

/**
 * mtd_ooblayout_free - Get the OOB region definition of a specific free
 *			section
 * @mtd: MTD device structure
 * @section: Free section you are interested in. Depending on the layout
 *	     you may have all the free bytes stored in a single contiguous
 *	     section, or one section per ECC chunk plus an extra section
 *	     for the remaining bytes (or other funky layout).
 * @oobfree: OOB region struct filled with the appropriate free position
 *	     information
 *
 * This functions return free bytes position in the OOB area. I you want
 * to get all the free bytes information, then you should call
 * mtd_ooblayout_free(mtd, section++, oobfree) until it returns -ERANGE.
 *
 * Returns zero on success, a negative error code otherwise.
 */
int mtd_ooblayout_free(struct mtd_info *mtd, int section,
		       struct mtd_oob_region *oobfree)
{
	memset(oobfree, 0, sizeof(*oobfree));

	if (!mtd || section < 0)
		return -EINVAL;

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	if (!mtd->ooblayout || !mtd->ooblayout->free)
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		return -ENOTSUPP;

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	return mtd->ooblayout->free(mtd, section, oobfree);
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}
EXPORT_SYMBOL_GPL(mtd_ooblayout_free);

/**
 * mtd_ooblayout_find_region - Find the region attached to a specific byte
 * @mtd: mtd info structure
 * @byte: the byte we are searching for
 * @sectionp: pointer where the section id will be stored
 * @oobregion: used to retrieve the ECC position
 * @iter: iterator function. Should be either mtd_ooblayout_free or
 *	  mtd_ooblayout_ecc depending on the region type you're searching for
 *
 * This functions returns the section id and oobregion information of a
 * specific byte. For example, say you want to know where the 4th ECC byte is
 * stored, you'll use:
 *
 * mtd_ooblayout_find_region(mtd, 3, &section, &oobregion, mtd_ooblayout_ecc);
 *
 * Returns zero on success, a negative error code otherwise.
 */
static int mtd_ooblayout_find_region(struct mtd_info *mtd, int byte,
				int *sectionp, struct mtd_oob_region *oobregion,
				int (*iter)(struct mtd_info *,
					    int section,
					    struct mtd_oob_region *oobregion))
{
	int pos = 0, ret, section = 0;

	memset(oobregion, 0, sizeof(*oobregion));

	while (1) {
		ret = iter(mtd, section, oobregion);
		if (ret)
			return ret;

		if (pos + oobregion->length > byte)
			break;

		pos += oobregion->length;
		section++;
	}

	/*
	 * Adjust region info to make it start at the beginning at the
	 * 'start' ECC byte.
	 */
	oobregion->offset += byte - pos;
	oobregion->length -= byte - pos;
	*sectionp = section;

	return 0;
}

/**
 * mtd_ooblayout_find_eccregion - Find the ECC region attached to a specific
 *				  ECC byte
 * @mtd: mtd info structure
 * @eccbyte: the byte we are searching for
 * @sectionp: pointer where the section id will be stored
 * @oobregion: OOB region information
 *
 * Works like mtd_ooblayout_find_region() except it searches for a specific ECC
 * byte.
 *
 * Returns zero on success, a negative error code otherwise.
 */
int mtd_ooblayout_find_eccregion(struct mtd_info *mtd, int eccbyte,
				 int *section,
				 struct mtd_oob_region *oobregion)
{
	return mtd_ooblayout_find_region(mtd, eccbyte, section, oobregion,
					 mtd_ooblayout_ecc);
}
EXPORT_SYMBOL_GPL(mtd_ooblayout_find_eccregion);

/**
 * mtd_ooblayout_get_bytes - Extract OOB bytes from the oob buffer
 * @mtd: mtd info structure
 * @buf: destination buffer to store OOB bytes
 * @oobbuf: OOB buffer
 * @start: first byte to retrieve
 * @nbytes: number of bytes to retrieve
 * @iter: section iterator
 *
 * Extract bytes attached to a specific category (ECC or free)
 * from the OOB buffer and copy them into buf.
 *
 * Returns zero on success, a negative error code otherwise.
 */
static int mtd_ooblayout_get_bytes(struct mtd_info *mtd, u8 *buf,
				const u8 *oobbuf, int start, int nbytes,
				int (*iter)(struct mtd_info *,
					    int section,
					    struct mtd_oob_region *oobregion))
{
	struct mtd_oob_region oobregion = { };
	int section = 0, ret;

	ret = mtd_ooblayout_find_region(mtd, start, &section,
					&oobregion, iter);

	while (!ret) {
		int cnt;

		cnt = oobregion.length > nbytes ? nbytes : oobregion.length;
		memcpy(buf, oobbuf + oobregion.offset, cnt);
		buf += cnt;
		nbytes -= cnt;

		if (!nbytes)
			break;

		ret = iter(mtd, ++section, &oobregion);
	}

	return ret;
}

/**
 * mtd_ooblayout_set_bytes - put OOB bytes into the oob buffer
 * @mtd: mtd info structure
 * @buf: source buffer to get OOB bytes from
 * @oobbuf: OOB buffer
 * @start: first OOB byte to set
 * @nbytes: number of OOB bytes to set
 * @iter: section iterator
 *
 * Fill the OOB buffer with data provided in buf. The category (ECC or free)
 * is selected by passing the appropriate iterator.
 *
 * Returns zero on success, a negative error code otherwise.
 */
static int mtd_ooblayout_set_bytes(struct mtd_info *mtd, const u8 *buf,
				u8 *oobbuf, int start, int nbytes,
				int (*iter)(struct mtd_info *,
					    int section,
					    struct mtd_oob_region *oobregion))
{
	struct mtd_oob_region oobregion = { };
	int section = 0, ret;

	ret = mtd_ooblayout_find_region(mtd, start, &section,
					&oobregion, iter);

	while (!ret) {
		int cnt;

		cnt = oobregion.length > nbytes ? nbytes : oobregion.length;
		memcpy(oobbuf + oobregion.offset, buf, cnt);
		buf += cnt;
		nbytes -= cnt;

		if (!nbytes)
			break;

		ret = iter(mtd, ++section, &oobregion);
	}

	return ret;
}

/**
 * mtd_ooblayout_count_bytes - count the number of bytes in a OOB category
 * @mtd: mtd info structure
 * @iter: category iterator
 *
 * Count the number of bytes in a given category.
 *
 * Returns a positive value on success, a negative error code otherwise.
 */
static int mtd_ooblayout_count_bytes(struct mtd_info *mtd,
				int (*iter)(struct mtd_info *,
					    int section,
					    struct mtd_oob_region *oobregion))
{
	struct mtd_oob_region oobregion = { };
	int section = 0, ret, nbytes = 0;

	while (1) {
		ret = iter(mtd, section++, &oobregion);
		if (ret) {
			if (ret == -ERANGE)
				ret = nbytes;
			break;
		}

		nbytes += oobregion.length;
	}

	return ret;
}

/**
 * mtd_ooblayout_get_eccbytes - extract ECC bytes from the oob buffer
 * @mtd: mtd info structure
 * @eccbuf: destination buffer to store ECC bytes
 * @oobbuf: OOB buffer
 * @start: first ECC byte to retrieve
 * @nbytes: number of ECC bytes to retrieve
 *
 * Works like mtd_ooblayout_get_bytes(), except it acts on ECC bytes.
 *
 * Returns zero on success, a negative error code otherwise.
 */
int mtd_ooblayout_get_eccbytes(struct mtd_info *mtd, u8 *eccbuf,
			       const u8 *oobbuf, int start, int nbytes)
{
	return mtd_ooblayout_get_bytes(mtd, eccbuf, oobbuf, start, nbytes,
				       mtd_ooblayout_ecc);
}
EXPORT_SYMBOL_GPL(mtd_ooblayout_get_eccbytes);

/**
 * mtd_ooblayout_set_eccbytes - set ECC bytes into the oob buffer
 * @mtd: mtd info structure
 * @eccbuf: source buffer to get ECC bytes from
 * @oobbuf: OOB buffer
 * @start: first ECC byte to set
 * @nbytes: number of ECC bytes to set
 *
 * Works like mtd_ooblayout_set_bytes(), except it acts on ECC bytes.
 *
 * Returns zero on success, a negative error code otherwise.
 */
int mtd_ooblayout_set_eccbytes(struct mtd_info *mtd, const u8 *eccbuf,
			       u8 *oobbuf, int start, int nbytes)
{
	return mtd_ooblayout_set_bytes(mtd, eccbuf, oobbuf, start, nbytes,
				       mtd_ooblayout_ecc);
}
EXPORT_SYMBOL_GPL(mtd_ooblayout_set_eccbytes);

/**
 * mtd_ooblayout_get_databytes - extract data bytes from the oob buffer
 * @mtd: mtd info structure
 * @databuf: destination buffer to store ECC bytes
 * @oobbuf: OOB buffer
 * @start: first ECC byte to retrieve
 * @nbytes: number of ECC bytes to retrieve
 *
 * Works like mtd_ooblayout_get_bytes(), except it acts on free bytes.
 *
 * Returns zero on success, a negative error code otherwise.
 */
int mtd_ooblayout_get_databytes(struct mtd_info *mtd, u8 *databuf,
				const u8 *oobbuf, int start, int nbytes)
{
	return mtd_ooblayout_get_bytes(mtd, databuf, oobbuf, start, nbytes,
				       mtd_ooblayout_free);
}
EXPORT_SYMBOL_GPL(mtd_ooblayout_get_databytes);

/**
 * mtd_ooblayout_get_eccbytes - set data bytes into the oob buffer
 * @mtd: mtd info structure
 * @eccbuf: source buffer to get data bytes from
 * @oobbuf: OOB buffer
 * @start: first ECC byte to set
 * @nbytes: number of ECC bytes to set
 *
 * Works like mtd_ooblayout_get_bytes(), except it acts on free bytes.
 *
 * Returns zero on success, a negative error code otherwise.
 */
int mtd_ooblayout_set_databytes(struct mtd_info *mtd, const u8 *databuf,
				u8 *oobbuf, int start, int nbytes)
{
	return mtd_ooblayout_set_bytes(mtd, databuf, oobbuf, start, nbytes,
				       mtd_ooblayout_free);
}
EXPORT_SYMBOL_GPL(mtd_ooblayout_set_databytes);

/**
 * mtd_ooblayout_count_freebytes - count the number of free bytes in OOB
 * @mtd: mtd info structure
 *
 * Works like mtd_ooblayout_count_bytes(), except it count free bytes.
 *
 * Returns zero on success, a negative error code otherwise.
 */
int mtd_ooblayout_count_freebytes(struct mtd_info *mtd)
{
	return mtd_ooblayout_count_bytes(mtd, mtd_ooblayout_free);
}
EXPORT_SYMBOL_GPL(mtd_ooblayout_count_freebytes);

/**
 * mtd_ooblayout_count_freebytes - count the number of ECC bytes in OOB
 * @mtd: mtd info structure
 *
 * Works like mtd_ooblayout_count_bytes(), except it count ECC bytes.
 *
 * Returns zero on success, a negative error code otherwise.
 */
int mtd_ooblayout_count_eccbytes(struct mtd_info *mtd)
{
	return mtd_ooblayout_count_bytes(mtd, mtd_ooblayout_ecc);
}
EXPORT_SYMBOL_GPL(mtd_ooblayout_count_eccbytes);

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/*
 * Method to access the protection register area, present in some flash
 * devices. The user data is one time programmable but the factory data is read
 * only.
 */
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int mtd_get_fact_prot_info(struct mtd_info *mtd, size_t len, size_t *retlen,
			   struct otp_info *buf)
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{
	if (!mtd->_get_fact_prot_info)
		return -EOPNOTSUPP;
	if (!len)
		return 0;
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	return mtd->_get_fact_prot_info(mtd, len, retlen, buf);
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}
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)
{
	*retlen = 0;
	if (!mtd->_read_fact_prot_reg)
		return -EOPNOTSUPP;
	if (!len)
		return 0;
	return mtd->_read_fact_prot_reg(mtd, from, len, retlen, buf);
}
EXPORT_SYMBOL_GPL(mtd_read_fact_prot_reg);

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int mtd_get_user_prot_info(struct mtd_info *mtd, size_t len, size_t *retlen,
			   struct otp_info *buf)
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{
	if (!mtd->_get_user_prot_info)
		return -EOPNOTSUPP;
	if (!len)
		return 0;
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	return mtd->_get_user_prot_info(mtd, len, retlen, buf);
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}
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)
{
	*retlen = 0;
	if (!mtd->_read_user_prot_reg)
		return -EOPNOTSUPP;
	if (!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)
{
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	int ret;

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	*retlen = 0;
	if (!mtd->_write_user_prot_reg)
		return -EOPNOTSUPP;
	if (!len)
		return 0;
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	ret = mtd->_write_user_prot_reg(mtd, to, len, retlen, buf);
	if (ret)
		return ret;

	/*
	 * If no data could be written at all, we are out of memory and
	 * must return -ENOSPC.
	 */
	return (*retlen) ? 0 : -ENOSPC;
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}
EXPORT_SYMBOL_GPL(mtd_write_user_prot_reg);

int mtd_lock_user_prot_reg(struct mtd_info *mtd, loff_t from, size_t len)
{
	if (!mtd->_lock_user_prot_reg)
		return -EOPNOTSUPP;
	if (!len)
		return 0;
	return mtd->_lock_user_prot_reg(mtd, from, len);
}
EXPORT_SYMBOL_GPL(mtd_lock_user_prot_reg);

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/* Chip-supported device locking */
int mtd_lock(struct mtd_info *mtd, loff_t ofs, uint64_t len)
{
	if (!mtd->_lock)
		return -EOPNOTSUPP;
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	if (ofs < 0 || ofs >= mtd->size || len > mtd->size - ofs)
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		return -EINVAL;
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	if (!len)
		return 0;
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	return mtd->_lock(mtd, ofs, len);
}
EXPORT_SYMBOL_GPL(mtd_lock);

int mtd_unlock(struct mtd_info *mtd, loff_t ofs, uint64_t len)
{
	if (!mtd->_unlock)
		return -EOPNOTSUPP;
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	if (ofs < 0 || ofs >= mtd->size || len > mtd->size - ofs)
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		return -EINVAL;
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	if (!len)
		return 0;
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	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;
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	if (ofs < 0 || ofs >= mtd->size || len > mtd->size - ofs)
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		return -EINVAL;
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	if (!len)
		return 0;
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	return mtd->_is_locked(mtd, ofs, len);
}
EXPORT_SYMBOL_GPL(mtd_is_locked);

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int mtd_block_isreserved(struct mtd_info *mtd, loff_t ofs)
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{
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	if (ofs < 0 || ofs >= mtd->size)
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		return -EINVAL;
	if (!mtd->_block_isreserved)
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		return 0;
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	return mtd->_block_isreserved(mtd, ofs);
}
EXPORT_SYMBOL_GPL(mtd_block_isreserved);

int mtd_block_isbad(struct mtd_info *mtd, loff_t ofs)
{
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	if (ofs < 0 || ofs >= mtd->size)
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		return -EINVAL;
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	if (!mtd->_block_isbad)
		return 0;
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	return mtd->_block_isbad(mtd, ofs);
}
EXPORT_SYMBOL_GPL(mtd_block_isbad);

int mtd_block_markbad(struct mtd_info *mtd, loff_t ofs)
{
	if (!mtd->_block_markbad)
		return -EOPNOTSUPP;
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	if (ofs < 0 || ofs >= mtd->size)
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		return -EINVAL;
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	if (!(mtd->flags & MTD_WRITEABLE))
		return -EROFS;
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	return mtd->_block_markbad(mtd, ofs);
}
EXPORT_SYMBOL_GPL(mtd_block_markbad);

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/*
 * 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.
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 */
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static int default_mtd_writev(struct mtd_info *mtd, const struct kvec *vecs,
			      unsigned long count, loff_t to, size_t *retlen)
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{
	unsigned long i;
	size_t totlen = 0, thislen;
	int ret = 0;

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	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;
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	}
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	*retlen = totlen;
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	return ret;
}
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/*
 * 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;
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