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	Version: linux-6.0.1 spark-3.0.0 hadoop-3.2.0-src hadoop-3.3.0-src spark-2.4.7 linux-4.15.13 hadoop-2.7.4-src Revert   Change

 // SPDX-License-Identifier: GPL-2.0-or-later
 /*
  * Core registration and callback routines for MTD
  * drivers and users.
  *
  * Copyright © 1999-2010 David Woodhouse <dwmw2@infradead.org>
  * Copyright © 2006      Red Hat UK Limited 
  */
 
 #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/of.h>
 #include <linux/proc_fs.h>
 #include <linux/idr.h>
 #include <linux/backing-dev.h>
 #include <linux/gfp.h>
 #include <linux/slab.h>
 #include <linux/reboot.h>
 #include <linux/leds.h>
 #include <linux/debugfs.h>
 #include <linux/nvmem-provider.h>
 
 #include <linux/mtd/mtd.h>
 #include <linux/mtd/partitions.h>
 
 #include "mtdcore.h"
 
 struct backing_dev_info *mtd_bdi;
 
 #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
 
 static struct class mtd_class = {
     .name = "mtd",
     .owner = THIS_MODULE,
     .pm = MTD_CLS_PM_OPS,
 };
 
 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);
 
 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 *mtd = dev_get_drvdata(dev);
     dev_t index = MTD_DEVT(mtd->index);
 
     /* remove /dev/mtdXro node */
     device_destroy(&mtd_class, index + 1);
 }
 
 #define MTD_DEVICE_ATTR_RO(name) \
 static DEVICE_ATTR(name, 0444, mtd_##name##_show, NULL)
 
 #define MTD_DEVICE_ATTR_RW(name) \
 static DEVICE_ATTR(name, 0644, mtd_##name##_show, mtd_##name##_store)
 
 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 sysfs_emit(buf, "%s\n", type);
 }
 MTD_DEVICE_ATTR_RO(type);
 
 static ssize_t mtd_flags_show(struct device *dev,
         struct device_attribute *attr, char *buf)
 {
     struct mtd_info *mtd = dev_get_drvdata(dev);
 
     return sysfs_emit(buf, "0x%lx\n", (unsigned long)mtd->flags);
 }
 MTD_DEVICE_ATTR_RO(flags);
 
 static ssize_t mtd_size_show(struct device *dev,
         struct device_attribute *attr, char *buf)
 {
     struct mtd_info *mtd = dev_get_drvdata(dev);
 
     return sysfs_emit(buf, "%llu\n", (unsigned long long)mtd->size);
 }
 MTD_DEVICE_ATTR_RO(size);
 
 static ssize_t mtd_erasesize_show(struct device *dev,
         struct device_attribute *attr, char *buf)
 {
     struct mtd_info *mtd = dev_get_drvdata(dev);
 
     return sysfs_emit(buf, "%lu\n", (unsigned long)mtd->erasesize);
 }
 MTD_DEVICE_ATTR_RO(erasesize);
 
 static ssize_t mtd_writesize_show(struct device *dev,
         struct device_attribute *attr, char *buf)
 {
     struct mtd_info *mtd = dev_get_drvdata(dev);
 
     return sysfs_emit(buf, "%lu\n", (unsigned long)mtd->writesize);
 }
 MTD_DEVICE_ATTR_RO(writesize);
 
 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 sysfs_emit(buf, "%u\n", subpagesize);
 }
 MTD_DEVICE_ATTR_RO(subpagesize);
 
 static ssize_t mtd_oobsize_show(struct device *dev,
         struct device_attribute *attr, char *buf)
 {
     struct mtd_info *mtd = dev_get_drvdata(dev);
 
     return sysfs_emit(buf, "%lu\n", (unsigned long)mtd->oobsize);
 }
 MTD_DEVICE_ATTR_RO(oobsize);
 
 static ssize_t mtd_oobavail_show(struct device *dev,
                  struct device_attribute *attr, char *buf)
 {
     struct mtd_info *mtd = dev_get_drvdata(dev);
 
     return sysfs_emit(buf, "%u\n", mtd->oobavail);
 }
 MTD_DEVICE_ATTR_RO(oobavail);
 
 static ssize_t mtd_numeraseregions_show(struct device *dev,
         struct device_attribute *attr, char *buf)
 {
     struct mtd_info *mtd = dev_get_drvdata(dev);
 
     return sysfs_emit(buf, "%u\n", mtd->numeraseregions);
 }
 MTD_DEVICE_ATTR_RO(numeraseregions);
 
 static ssize_t mtd_name_show(struct device *dev,
         struct device_attribute *attr, char *buf)
 {
     struct mtd_info *mtd = dev_get_drvdata(dev);
 
     return sysfs_emit(buf, "%s\n", mtd->name);
 }
 MTD_DEVICE_ATTR_RO(name);
 
 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 sysfs_emit(buf, "%u\n", mtd->ecc_strength);
 }
 MTD_DEVICE_ATTR_RO(ecc_strength);
 
 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 sysfs_emit(buf, "%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;
 }
 MTD_DEVICE_ATTR_RW(bitflip_threshold);
 
 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 sysfs_emit(buf, "%u\n", mtd->ecc_step_size);
 
 }
 MTD_DEVICE_ATTR_RO(ecc_step_size);
 
 static ssize_t mtd_corrected_bits_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 sysfs_emit(buf, "%u\n", ecc_stats->corrected);
 }
 MTD_DEVICE_ATTR_RO(corrected_bits); /* ecc stats corrected */
 
 static ssize_t mtd_ecc_failures_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 sysfs_emit(buf, "%u\n", ecc_stats->failed);
 }
 MTD_DEVICE_ATTR_RO(ecc_failures);   /* ecc stats errors */
 
 static ssize_t mtd_bad_blocks_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 sysfs_emit(buf, "%u\n", ecc_stats->badblocks);
 }
 MTD_DEVICE_ATTR_RO(bad_blocks);
 
 static ssize_t mtd_bbt_blocks_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 sysfs_emit(buf, "%u\n", ecc_stats->bbtblocks);
 }
 MTD_DEVICE_ATTR_RO(bbt_blocks);
 
 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_oobavail.attr,
     &dev_attr_numeraseregions.attr,
     &dev_attr_name.attr,
     &dev_attr_ecc_strength.attr,
     &dev_attr_ecc_step_size.attr,
     &dev_attr_corrected_bits.attr,
     &dev_attr_ecc_failures.attr,
     &dev_attr_bad_blocks.attr,
     &dev_attr_bbt_blocks.attr,
     &dev_attr_bitflip_threshold.attr,
     NULL,
 };
 ATTRIBUTE_GROUPS(mtd);
 
 static const struct device_type mtd_devtype = {
     .name       = "mtd",
     .groups     = mtd_groups,
     .release    = mtd_release,
 };
 
 static bool mtd_expert_analysis_mode;
 
 #ifdef CONFIG_DEBUG_FS
 bool mtd_check_expert_analysis_mode(void)
 {
     const char *mtd_expert_analysis_warning =
         "Bad block checks have been entirely disabled.\n"
         "This is only reserved for post-mortem forensics and debug purposes.\n"
         "Never enable this mode if you do not know what you are doing!\n";
 
     return WARN_ONCE(mtd_expert_analysis_mode, mtd_expert_analysis_warning);
 }
 EXPORT_SYMBOL_GPL(mtd_check_expert_analysis_mode);
 #endif
 
 static struct dentry *dfs_dir_mtd;
 
 static void mtd_debugfs_populate(struct mtd_info *mtd)
 {
     struct device *dev = &mtd->dev;
 
     if (IS_ERR_OR_NULL(dfs_dir_mtd))
         return;
 
     mtd->dbg.dfs_dir = debugfs_create_dir(dev_name(dev), dfs_dir_mtd);
 }
 
 #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;
     }
 }
 EXPORT_SYMBOL_GPL(mtd_mmap_capabilities);
 #endif
 
 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;
 }
 
 /**
  * mtd_wunit_to_pairing_info - get pairing information of a wunit
  * @mtd: pointer to new MTD device info structure
  * @wunit: write unit we are interested in
  * @info: returned pairing information
  *
  * Retrieve pairing information associated to the wunit.
  * This is mainly useful when dealing with MLC/TLC NANDs where pages can be
  * paired together, and where programming a page may influence the page it is
  * paired with.
  * The notion of page is replaced by the term wunit (write-unit) to stay
  * consistent with the ->writesize field.
  *
  * The @wunit argument can be extracted from an absolute offset using
  * mtd_offset_to_wunit(). @info is filled with the pairing information attached
  * to @wunit.
  *
  * From the pairing info the MTD user can find all the wunits paired with
  * @wunit using the following loop:
  *
  * for (i = 0; i < mtd_pairing_groups(mtd); i++) {
  *  info.pair = i;
  *  mtd_pairing_info_to_wunit(mtd, &info);
  *  ...
  * }
  */
 int mtd_wunit_to_pairing_info(struct mtd_info *mtd, int wunit,
                   struct mtd_pairing_info *info)
 {
     struct mtd_info *master = mtd_get_master(mtd);
     int npairs = mtd_wunit_per_eb(master) / mtd_pairing_groups(master);
 
     if (wunit < 0 || wunit >= npairs)
         return -EINVAL;
 
     if (master->pairing && master->pairing->get_info)
         return master->pairing->get_info(master, wunit, info);
 
     info->group = 0;
     info->pair = wunit;
 
     return 0;
 }
 EXPORT_SYMBOL_GPL(mtd_wunit_to_pairing_info);
 
 /**
  * mtd_pairing_info_to_wunit - get wunit from pairing information
  * @mtd: pointer to new MTD device info structure
  * @info: pairing information struct
  *
  * Returns a positive number representing the wunit associated to the info
  * struct, or a negative error code.
  *
  * This is the reverse of mtd_wunit_to_pairing_info(), and can help one to
  * iterate over all wunits of a given pair (see mtd_wunit_to_pairing_info()
  * doc).
  *
  * It can also be used to only program the first page of each pair (i.e.
  * page attached to group 0), which allows one to use an MLC NAND in
  * software-emulated SLC mode:
  *
  * info.group = 0;
  * npairs = mtd_wunit_per_eb(mtd) / mtd_pairing_groups(mtd);
  * for (info.pair = 0; info.pair < npairs; info.pair++) {
  *  wunit = mtd_pairing_info_to_wunit(mtd, &info);
  *  mtd_write(mtd, mtd_wunit_to_offset(mtd, blkoffs, wunit),
  *        mtd->writesize, &retlen, buf + (i * mtd->writesize));
  * }
  */
 int mtd_pairing_info_to_wunit(struct mtd_info *mtd,
                   const struct mtd_pairing_info *info)
 {
     struct mtd_info *master = mtd_get_master(mtd);
     int ngroups = mtd_pairing_groups(master);
     int npairs = mtd_wunit_per_eb(master) / ngroups;
 
     if (!info || info->pair < 0 || info->pair >= npairs ||
         info->group < 0 || info->group >= ngroups)
         return -EINVAL;
 
     if (master->pairing && master->pairing->get_wunit)
         return mtd->pairing->get_wunit(master, info);
 
     return info->pair;
 }
 EXPORT_SYMBOL_GPL(mtd_pairing_info_to_wunit);
 
 /**
  * mtd_pairing_groups - get the number of pairing groups
  * @mtd: pointer to new MTD device info structure
  *
  * Returns the number of pairing groups.
  *
  * This number is usually equal to the number of bits exposed by a single
  * cell, and can be used in conjunction with mtd_pairing_info_to_wunit()
  * to iterate over all pages of a given pair.
  */
 int mtd_pairing_groups(struct mtd_info *mtd)
 {
     struct mtd_info *master = mtd_get_master(mtd);
 
     if (!master->pairing || !master->pairing->ngroups)
         return 1;
 
     return master->pairing->ngroups;
 }
 EXPORT_SYMBOL_GPL(mtd_pairing_groups);
 
 static int mtd_nvmem_reg_read(void *priv, unsigned int offset,
                   void *val, size_t bytes)
 {
     struct mtd_info *mtd = priv;
     size_t retlen;
     int err;
 
     err = mtd_read(mtd, offset, bytes, &retlen, val);
     if (err && err != -EUCLEAN)
         return err;
 
     return retlen == bytes ? 0 : -EIO;
 }
 
 static int mtd_nvmem_add(struct mtd_info *mtd)
 {
     struct device_node *node = mtd_get_of_node(mtd);
     struct nvmem_config config = {};
 
     config.id = -1;
     config.dev = &mtd->dev;
     config.name = dev_name(&mtd->dev);
     config.owner = THIS_MODULE;
     config.reg_read = mtd_nvmem_reg_read;
     config.size = mtd->size;
     config.word_size = 1;
     config.stride = 1;
     config.read_only = true;
     config.root_only = true;
     config.ignore_wp = true;
     config.no_of_node = !of_device_is_compatible(node, "nvmem-cells");
     config.priv = mtd;
 
     mtd->nvmem = nvmem_register(&config);
     if (IS_ERR(mtd->nvmem)) {
         /* Just ignore if there is no NVMEM support in the kernel */
         if (PTR_ERR(mtd->nvmem) == -EOPNOTSUPP) {
             mtd->nvmem = NULL;
         } else {
             dev_err(&mtd->dev, "Failed to register NVMEM device\n");
             return PTR_ERR(mtd->nvmem);
         }
     }
 
     return 0;
 }
 
 static void mtd_check_of_node(struct mtd_info *mtd)
 {
     struct device_node *partitions, *parent_dn, *mtd_dn = NULL;
     const char *pname, *prefix = "partition-";
     int plen, mtd_name_len, offset, prefix_len;
     struct mtd_info *parent;
     bool found = false;
 
     /* Check if MTD already has a device node */
     if (dev_of_node(&mtd->dev))
         return;
 
     /* Check if a partitions node exist */
     if (!mtd_is_partition(mtd))
         return;
     parent = mtd->parent;
     parent_dn = dev_of_node(&parent->dev);
     if (!parent_dn)
         return;
 
     partitions = of_get_child_by_name(parent_dn, "partitions");
     if (!partitions)
         goto exit_parent;
 
     prefix_len = strlen(prefix);
     mtd_name_len = strlen(mtd->name);
 
     /* Search if a partition is defined with the same name */
     for_each_child_of_node(partitions, mtd_dn) {
         offset = 0;
 
         /* Skip partition with no/wrong prefix */
         if (!of_node_name_prefix(mtd_dn, "partition-"))
             continue;
 
         /* Label have priority. Check that first */
         if (of_property_read_string(mtd_dn, "label", &pname)) {
             of_property_read_string(mtd_dn, "name", &pname);
             offset = prefix_len;
         }
 
         plen = strlen(pname) - offset;
         if (plen == mtd_name_len &&
             !strncmp(mtd->name, pname + offset, plen)) {
             found = true;
             break;
         }
     }
 
     if (!found)
         goto exit_partitions;
 
     /* Set of_node only for nvmem */
     if (of_device_is_compatible(mtd_dn, "nvmem-cells"))
         mtd_set_of_node(mtd, mtd_dn);
 
 exit_partitions:
     of_node_put(partitions);
 exit_parent:
     of_node_put(parent_dn);
 }
 
 /**
  *  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 non-zero on failure.
  */
 
 int add_mtd_device(struct mtd_info *mtd)
 {
     struct device_node *np = mtd_get_of_node(mtd);
     struct mtd_info *master = mtd_get_master(mtd);
     struct mtd_notifier *not;
     int i, error, ofidx;
 
     /*
      * 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->dev.type, "MTD already registered\n"))
         return -EEXIST;
 
     BUG_ON(mtd->writesize == 0);
 
     /*
      * MTD drivers should implement ->_{write,read}() or
      * ->_{write,read}_oob(), but not both.
      */
     if (WARN_ON((mtd->_write && mtd->_write_oob) ||
             (mtd->_read && mtd->_read_oob)))
         return -EINVAL;
 
     if (WARN_ON((!mtd->erasesize || !master->_erase) &&
             !(mtd->flags & MTD_NO_ERASE)))
         return -EINVAL;
 
     /*
      * MTD_SLC_ON_MLC_EMULATION can only be set on partitions, when the
      * master is an MLC NAND and has a proper pairing scheme defined.
      * We also reject masters that implement ->_writev() for now, because
      * NAND controller drivers don't implement this hook, and adding the
      * SLC -> MLC address/length conversion to this path is useless if we
      * don't have a user.
      */
     if (mtd->flags & MTD_SLC_ON_MLC_EMULATION &&
         (!mtd_is_partition(mtd) || master->type != MTD_MLCNANDFLASH ||
          !master->pairing || master->_writev))
         return -EINVAL;
 
     mutex_lock(&mtd_table_mutex);
 
     ofidx = -1;
     if (np)
         ofidx = of_alias_get_id(np, "mtd");
     if (ofidx >= 0)
         i = idr_alloc(&mtd_idr, mtd, ofidx, ofidx + 1, GFP_KERNEL);
     else
         i = idr_alloc(&mtd_idr, mtd, 0, 0, GFP_KERNEL);
     if (i < 0) {
         error = i;
         goto fail_locked;
     }
 
     mtd->index = i;
     mtd->usecount = 0;
 
     /* default value if not set by driver */
     if (mtd->bitflip_threshold == 0)
         mtd->bitflip_threshold = mtd->ecc_strength;
 
     if (mtd->flags & MTD_SLC_ON_MLC_EMULATION) {
         int ngroups = mtd_pairing_groups(master);
 
         mtd->erasesize /= ngroups;
         mtd->size = (u64)mtd_div_by_eb(mtd->size, master) *
                 mtd->erasesize;
     }
 
     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 */
     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);
         /* Ignore unlock failures? */
         error = 0;
     }
 
     /* Caller should have set dev.parent to match the
      * physical device, if appropriate.
      */
     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);
     mtd_check_of_node(mtd);
     of_node_get(mtd_get_of_node(mtd));
     error = device_register(&mtd->dev);
     if (error)
         goto fail_added;
 
     /* Add the nvmem provider */
     error = mtd_nvmem_add(mtd);
     if (error)
         goto fail_nvmem_add;
 
     mtd_debugfs_populate(mtd);
 
     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);
 
     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;
 
 fail_nvmem_add:
     device_unregister(&mtd->dev);
 fail_added:
     of_node_put(mtd_get_of_node(mtd));
     idr_remove(&mtd_idr, i);
 fail_locked:
     mutex_unlock(&mtd_table_mutex);
     return error;
 }
 
 /**
  *  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.
  */
 
 int del_mtd_device(struct mtd_info *mtd)
 {
     int ret;
     struct mtd_notifier *not;
 
     mutex_lock(&mtd_table_mutex);
 
     if (idr_find(&mtd_idr, mtd->index) != mtd) {
         ret = -ENODEV;
         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) {
         printk(KERN_NOTICE "Removing MTD device #%d (%s) with use count %d\n",
                mtd->index, mtd->name, mtd->usecount);
         ret = -EBUSY;
     } else {
         debugfs_remove_recursive(mtd->dbg.dfs_dir);
 
         /* Try to remove the NVMEM provider */
         nvmem_unregister(mtd->nvmem);
 
         device_unregister(&mtd->dev);
 
         /* Clear dev so mtd can be safely re-registered later if desired */
         memset(&mtd->dev, 0, sizeof(mtd->dev));
 
         idr_remove(&mtd_idr, mtd->index);
         of_node_put(mtd_get_of_node(mtd));
 
         module_put(THIS_MODULE);
         ret = 0;
     }
 
 out_error:
     mutex_unlock(&mtd_table_mutex);
     return ret;
 }
 
 /*
  * 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");
     }
 
     INIT_LIST_HEAD(&mtd->partitions);
     mutex_init(&mtd->master.partitions_lock);
     mutex_init(&mtd->master.chrdev_lock);
 }
 
 static ssize_t mtd_otp_size(struct mtd_info *mtd, bool is_user)
 {
     struct otp_info *info;
     ssize_t size = 0;
     unsigned int i;
     size_t retlen;
     int ret;
 
     info = kmalloc(PAGE_SIZE, GFP_KERNEL);
     if (!info)
         return -ENOMEM;
 
     if (is_user)
         ret = mtd_get_user_prot_info(mtd, PAGE_SIZE, &retlen, info);
     else
         ret = mtd_get_fact_prot_info(mtd, PAGE_SIZE, &retlen, info);
     if (ret)
         goto err;
 
     for (i = 0; i < retlen / sizeof(*info); i++)
         size += info[i].length;
 
     kfree(info);
     return size;
 
 err:
     kfree(info);
 
     /* ENODATA means there is no OTP region. */
     return ret == -ENODATA ? 0 : ret;
 }
 
 static struct nvmem_device *mtd_otp_nvmem_register(struct mtd_info *mtd,
                            const char *compatible,
                            int size,
                            nvmem_reg_read_t reg_read)
 {
     struct nvmem_device *nvmem = NULL;
     struct nvmem_config config = {};
     struct device_node *np;
 
     /* DT binding is optional */
     np = of_get_compatible_child(mtd->dev.of_node, compatible);
 
     /* OTP nvmem will be registered on the physical device */
     config.dev = mtd->dev.parent;
     config.name = kasprintf(GFP_KERNEL, "%s-%s", dev_name(&mtd->dev), compatible);
     config.id = NVMEM_DEVID_NONE;
     config.owner = THIS_MODULE;
     config.type = NVMEM_TYPE_OTP;
     config.root_only = true;
     config.ignore_wp = true;
     config.reg_read = reg_read;
     config.size = size;
     config.of_node = np;
     config.priv = mtd;
 
     nvmem = nvmem_register(&config);
     /* Just ignore if there is no NVMEM support in the kernel */
     if (IS_ERR(nvmem) && PTR_ERR(nvmem) == -EOPNOTSUPP)
         nvmem = NULL;
 
     of_node_put(np);
     kfree(config.name);
 
     return nvmem;
 }
 
 static int mtd_nvmem_user_otp_reg_read(void *priv, unsigned int offset,
                        void *val, size_t bytes)
 {
     struct mtd_info *mtd = priv;
     size_t retlen;
     int ret;
 
     ret = mtd_read_user_prot_reg(mtd, offset, bytes, &retlen, val);
     if (ret)
         return ret;
 
     return retlen == bytes ? 0 : -EIO;
 }
 
 static int mtd_nvmem_fact_otp_reg_read(void *priv, unsigned int offset,
                        void *val, size_t bytes)
 {
     struct mtd_info *mtd = priv;
     size_t retlen;
     int ret;
 
     ret = mtd_read_fact_prot_reg(mtd, offset, bytes, &retlen, val);
     if (ret)
         return ret;
 
     return retlen == bytes ? 0 : -EIO;
 }
 
 static int mtd_otp_nvmem_add(struct mtd_info *mtd)
 {
     struct nvmem_device *nvmem;
     ssize_t size;
     int err;
 
     if (mtd->_get_user_prot_info && mtd->_read_user_prot_reg) {
         size = mtd_otp_size(mtd, true);
         if (size < 0)
             return size;
 
         if (size > 0) {
             nvmem = mtd_otp_nvmem_register(mtd, "user-otp", size,
                                mtd_nvmem_user_otp_reg_read);
             if (IS_ERR(nvmem)) {
                 dev_err(&mtd->dev, "Failed to register OTP NVMEM device\n");
                 return PTR_ERR(nvmem);
             }
             mtd->otp_user_nvmem = nvmem;
         }
     }
 
     if (mtd->_get_fact_prot_info && mtd->_read_fact_prot_reg) {
         size = mtd_otp_size(mtd, false);
         if (size < 0) {
             err = size;
             goto err;
         }
 
         if (size > 0) {
             nvmem = mtd_otp_nvmem_register(mtd, "factory-otp", size,
                                mtd_nvmem_fact_otp_reg_read);
             if (IS_ERR(nvmem)) {
                 dev_err(&mtd->dev, "Failed to register OTP NVMEM device\n");
                 err = PTR_ERR(nvmem);
                 goto err;
             }
             mtd->otp_factory_nvmem = nvmem;
         }
     }
 
     return 0;
 
 err:
     nvmem_unregister(mtd->otp_user_nvmem);
     return err;
 }
 
 /**
  * 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:
  *
  * * If the MTD_PARTITIONED_MASTER option is set, then the device as a whole is
  *   registered first.
  * * Then It 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 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 ret;
 
     mtd_set_dev_defaults(mtd);
 
     if (IS_ENABLED(CONFIG_MTD_PARTITIONED_MASTER)) {
         ret = add_mtd_device(mtd);
         if (ret)
             return ret;
     }
 
     /* Prefer parsed partitions over driver-provided fallback */
     ret = parse_mtd_partitions(mtd, types, parser_data);
     if (ret == -EPROBE_DEFER)
         goto out;
 
     if (ret > 0)
         ret = 0;
     else if (nr_parts)
         ret = add_mtd_partitions(mtd, parts, nr_parts);
     else if (!device_is_registered(&mtd->dev))
         ret = add_mtd_device(mtd);
     else
         ret = 0;
 
     if (ret)
         goto out;
 
     /*
      * 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).
      */
     WARN_ONCE(mtd->_reboot && mtd->reboot_notifier.notifier_call,
           "MTD already registered\n");
     if (mtd->_reboot && !mtd->reboot_notifier.notifier_call) {
         mtd->reboot_notifier.notifier_call = mtd_reboot_notifier;
         register_reboot_notifier(&mtd->reboot_notifier);
     }
 
     ret = mtd_otp_nvmem_add(mtd);
 
 out:
     if (ret && device_is_registered(&mtd->dev))
         del_mtd_device(mtd);
 
     return ret;
 }
 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;
 
     if (master->_reboot) {
         unregister_reboot_notifier(&master->reboot_notifier);
         memset(&master->reboot_notifier, 0, sizeof(master->reboot_notifier));
     }
 
     nvmem_unregister(master->otp_user_nvmem);
     nvmem_unregister(master->otp_factory_nvmem);
 
     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);
 
 /**
  *  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.
  */
 struct mtd_info *get_mtd_device(struct mtd_info *mtd, int num)
 {
     struct mtd_info *ret = NULL, *other;
     int err = -ENODEV;
 
     mutex_lock(&mtd_table_mutex);
 
     if (num == -1) {
         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) {
         ret = ERR_PTR(err);
         goto out;
     }
 
     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);
 
 
 int __get_mtd_device(struct mtd_info *mtd)
 {
     struct mtd_info *master = mtd_get_master(mtd);
     int err;
 
     if (!try_module_get(master->owner))
         return -ENODEV;
 
     if (master->_get_device) {
         err = master->_get_device(mtd);
 
         if (err) {
             module_put(master->owner);
             return err;
         }
     }
 
     master->usecount++;
 
     while (mtd->parent) {
         mtd->usecount++;
         mtd = mtd->parent;
     }
 
     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
  *
  *  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 err = -ENODEV;
     struct mtd_info *mtd = NULL, *other;
 
     mutex_lock(&mtd_table_mutex);
 
     mtd_for_each_device(other) {
         if (!strcmp(name, other->name)) {
             mtd = other;
             break;
         }
     }
 
     if (!mtd)
         goto out_unlock;
 
     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);
 }
 EXPORT_SYMBOL_GPL(get_mtd_device_nm);
 
 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)
 {
     struct mtd_info *master = mtd_get_master(mtd);
 
     while (mtd->parent) {
         --mtd->usecount;
         BUG_ON(mtd->usecount < 0);
         mtd = mtd->parent;
     }
 
     master->usecount--;
 
     if (master->_put_device)
         master->_put_device(master);
 
     module_put(master->owner);
 }
 EXPORT_SYMBOL_GPL(__put_mtd_device);
 
 /*
  * Erase is an synchronous operation. Device drivers are epected to return a
  * negative error code if the operation failed and update instr->fail_addr
  * to point the portion that was not properly erased.
  */
 int mtd_erase(struct mtd_info *mtd, struct erase_info *instr)
 {
     struct mtd_info *master = mtd_get_master(mtd);
     u64 mst_ofs = mtd_get_master_ofs(mtd, 0);
     struct erase_info adjinstr;
     int ret;
 
     instr->fail_addr = MTD_FAIL_ADDR_UNKNOWN;
     adjinstr = *instr;
 
     if (!mtd->erasesize || !master->_erase)
         return -ENOTSUPP;
 
     if (instr->addr >= mtd->size || instr->len > mtd->size - instr->addr)
         return -EINVAL;
     if (!(mtd->flags & MTD_WRITEABLE))
         return -EROFS;
 
     if (!instr->len)
         return 0;
 
     ledtrig_mtd_activity();
 
     if (mtd->flags & MTD_SLC_ON_MLC_EMULATION) {
         adjinstr.addr = (loff_t)mtd_div_by_eb(instr->addr, mtd) *
                 master->erasesize;
         adjinstr.len = ((u64)mtd_div_by_eb(instr->addr + instr->len, mtd) *
                 master->erasesize) -
                    adjinstr.addr;
     }
 
     adjinstr.addr += mst_ofs;
 
     ret = master->_erase(master, &adjinstr);
 
     if (adjinstr.fail_addr != MTD_FAIL_ADDR_UNKNOWN) {
         instr->fail_addr = adjinstr.fail_addr - mst_ofs;
         if (mtd->flags & MTD_SLC_ON_MLC_EMULATION) {
             instr->fail_addr = mtd_div_by_eb(instr->fail_addr,
                              master);
             instr->fail_addr *= mtd->erasesize;
         }
     }
 
     return ret;
 }
 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)
 {
     struct mtd_info *master = mtd_get_master(mtd);
 
     *retlen = 0;
     *virt = NULL;
     if (phys)
         *phys = 0;
     if (!master->_point)
         return -EOPNOTSUPP;
     if (from < 0 || from >= mtd->size || len > mtd->size - from)
         return -EINVAL;
     if (!len)
         return 0;
 
     from = mtd_get_master_ofs(mtd, from);
     return master->_point(master, 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)
 {
     struct mtd_info *master = mtd_get_master(mtd);
 
     if (!master->_unpoint)
         return -EOPNOTSUPP;
     if (from < 0 || from >= mtd->size || len > mtd->size - from)
         return -EINVAL;
     if (!len)
         return 0;
     return master->_unpoint(master, mtd_get_master_ofs(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)
 {
     size_t retlen;
     void *virt;
     int ret;
 
     ret = mtd_point(mtd, offset, len, &retlen, &virt, NULL);
     if (ret)
         return ret;
     if (retlen != len) {
         mtd_unpoint(mtd, offset, retlen);
         return -ENOSYS;
     }
     return (unsigned long)virt;
 }
 EXPORT_SYMBOL_GPL(mtd_get_unmapped_area);
 
 static void mtd_update_ecc_stats(struct mtd_info *mtd, struct mtd_info *master,
                  const struct mtd_ecc_stats *old_stats)
 {
     struct mtd_ecc_stats diff;
 
     if (master == mtd)
         return;
 
     diff = master->ecc_stats;
     diff.failed -= old_stats->failed;
     diff.corrected -= old_stats->corrected;
 
     while (mtd->parent) {
         mtd->ecc_stats.failed += diff.failed;
         mtd->ecc_stats.corrected += diff.corrected;
         mtd = mtd->parent;
     }
 }
 
 int mtd_read(struct mtd_info *mtd, loff_t from, size_t len, size_t *retlen,
          u_char *buf)
 {
     struct mtd_oob_ops ops = {
         .len = len,
         .datbuf = buf,
     };
     int ret;
 
     ret = mtd_read_oob(mtd, from, &ops);
     *retlen = ops.retlen;
 
     return ret;
 }
 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)
 {
     struct mtd_oob_ops ops = {
         .len = len,
         .datbuf = (u8 *)buf,
     };
     int ret;
 
     ret = mtd_write_oob(mtd, to, &ops);
     *retlen = ops.retlen;
 
     return ret;
 }
 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)
 {
     struct mtd_info *master = mtd_get_master(mtd);
 
     *retlen = 0;
     if (!master->_panic_write)
         return -EOPNOTSUPP;
     if (to < 0 || to >= mtd->size || len > mtd->size - to)
         return -EINVAL;
     if (!(mtd->flags & MTD_WRITEABLE))
         return -EROFS;
     if (!len)
         return 0;
     if (!master->oops_panic_write)
         master->oops_panic_write = true;
 
     return master->_panic_write(master, mtd_get_master_ofs(mtd, to), len,
                     retlen, buf);
 }
 EXPORT_SYMBOL_GPL(mtd_panic_write);
 
 static int mtd_check_oob_ops(struct mtd_info *mtd, loff_t offs,
                  struct mtd_oob_ops *ops)
 {
     /*
      * Some users are setting ->datbuf or ->oobbuf to NULL, but are leaving
      * ->len or ->ooblen uninitialized. Force ->len and ->ooblen to 0 in
      *  this case.
      */
     if (!ops->datbuf)
         ops->len = 0;
 
     if (!ops->oobbuf)
         ops->ooblen = 0;
 
     if (offs < 0 || offs + ops->len > mtd->size)
         return -EINVAL;
 
     if (ops->ooblen) {
         size_t maxooblen;
 
         if (ops->ooboffs >= mtd_oobavail(mtd, ops))
             return -EINVAL;
 
         maxooblen = ((size_t)(mtd_div_by_ws(mtd->size, mtd) -
                       mtd_div_by_ws(offs, mtd)) *
                  mtd_oobavail(mtd, ops)) - ops->ooboffs;
         if (ops->ooblen > maxooblen)
             return -EINVAL;
     }
 
     return 0;
 }
 
 static int mtd_read_oob_std(struct mtd_info *mtd, loff_t from,
                 struct mtd_oob_ops *ops)
 {
     struct mtd_info *master = mtd_get_master(mtd);
     int ret;
 
     from = mtd_get_master_ofs(mtd, from);
     if (master->_read_oob)
         ret = master->_read_oob(master, from, ops);
     else
         ret = master->_read(master, from, ops->len, &ops->retlen,
                     ops->datbuf);
 
     return ret;
 }
 
 static int mtd_write_oob_std(struct mtd_info *mtd, loff_t to,
                  struct mtd_oob_ops *ops)
 {
     struct mtd_info *master = mtd_get_master(mtd);
     int ret;
 
     to = mtd_get_master_ofs(mtd, to);
     if (master->_write_oob)
         ret = master->_write_oob(master, to, ops);
     else
         ret = master->_write(master, to, ops->len, &ops->retlen,
                      ops->datbuf);
 
     return ret;
 }
 
 static int mtd_io_emulated_slc(struct mtd_info *mtd, loff_t start, bool read,
                    struct mtd_oob_ops *ops)
 {
     struct mtd_info *master = mtd_get_master(mtd);
     int ngroups = mtd_pairing_groups(master);
     int npairs = mtd_wunit_per_eb(master) / ngroups;
     struct mtd_oob_ops adjops = *ops;
     unsigned int wunit, oobavail;
     struct mtd_pairing_info info;
     int max_bitflips = 0;
     u32 ebofs, pageofs;
     loff_t base, pos;
 
     ebofs = mtd_mod_by_eb(start, mtd);
     base = (loff_t)mtd_div_by_eb(start, mtd) * master->erasesize;
     info.group = 0;
     info.pair = mtd_div_by_ws(ebofs, mtd);
     pageofs = mtd_mod_by_ws(ebofs, mtd);
     oobavail = mtd_oobavail(mtd, ops);
 
     while (ops->retlen < ops->len || ops->oobretlen < ops->ooblen) {
         int ret;
 
         if (info.pair >= npairs) {
             info.pair = 0;
             base += master->erasesize;
         }
 
         wunit = mtd_pairing_info_to_wunit(master, &info);
         pos = mtd_wunit_to_offset(mtd, base, wunit);
 
         adjops.len = ops->len - ops->retlen;
         if (adjops.len > mtd->writesize - pageofs)
             adjops.len = mtd->writesize - pageofs;
 
         adjops.ooblen = ops->ooblen - ops->oobretlen;
         if (adjops.ooblen > oobavail - adjops.ooboffs)
             adjops.ooblen = oobavail - adjops.ooboffs;
 
         if (read) {
             ret = mtd_read_oob_std(mtd, pos + pageofs, &adjops);
             if (ret > 0)
                 max_bitflips = max(max_bitflips, ret);
         } else {
             ret = mtd_write_oob_std(mtd, pos + pageofs, &adjops);
         }
 
         if (ret < 0)
             return ret;
 
         max_bitflips = max(max_bitflips, ret);
         ops->retlen += adjops.retlen;
         ops->oobretlen += adjops.oobretlen;
         adjops.datbuf += adjops.retlen;
         adjops.oobbuf += adjops.oobretlen;
         adjops.ooboffs = 0;
         pageofs = 0;
         info.pair++;
     }
 
     return max_bitflips;
 }
 
 int mtd_read_oob(struct mtd_info *mtd, loff_t from, struct mtd_oob_ops *ops)
 {
     struct mtd_info *master = mtd_get_master(mtd);
     struct mtd_ecc_stats old_stats = master->ecc_stats;
     int ret_code;
 
     ops->retlen = ops->oobretlen = 0;
 
     ret_code = mtd_check_oob_ops(mtd, from, ops);
     if (ret_code)
         return ret_code;
 
     ledtrig_mtd_activity();
 
     /* Check the validity of a potential fallback on mtd->_read */
     if (!master->_read_oob && (!master->_read || ops->oobbuf))
         return -EOPNOTSUPP;
 
     if (mtd->flags & MTD_SLC_ON_MLC_EMULATION)
         ret_code = mtd_io_emulated_slc(mtd, from, true, ops);
     else
         ret_code = mtd_read_oob_std(mtd, from, ops);
 
     mtd_update_ecc_stats(mtd, master, &old_stats);
 
     /*
      * 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().
      */
     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);
 
 int mtd_write_oob(struct mtd_info *mtd, loff_t to,
                 struct mtd_oob_ops *ops)
 {
     struct mtd_info *master = mtd_get_master(mtd);
     int ret;
 
     ops->retlen = ops->oobretlen = 0;
 
     if (!(mtd->flags & MTD_WRITEABLE))
         return -EROFS;
 
     ret = mtd_check_oob_ops(mtd, to, ops);
     if (ret)
         return ret;
 
     ledtrig_mtd_activity();
 
     /* Check the validity of a potential fallback on mtd->_write */
     if (!master->_write_oob && (!master->_write || ops->oobbuf))
         return -EOPNOTSUPP;
 
     if (mtd->flags & MTD_SLC_ON_MLC_EMULATION)
         return mtd_io_emulated_slc(mtd, to, false, ops);
 
     return mtd_write_oob_std(mtd, to, ops);
 }
 EXPORT_SYMBOL_GPL(mtd_write_oob);
 
 /**
  * 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 function returns ECC section information in the OOB area. If 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)
 {
     struct mtd_info *master = mtd_get_master(mtd);
 
     memset(oobecc, 0, sizeof(*oobecc));
 
     if (!master || section < 0)
         return -EINVAL;
 
     if (!master->ooblayout || !master->ooblayout->ecc)
         return -ENOTSUPP;
 
     return master->ooblayout->ecc(master, section, oobecc);
 }
 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 function returns free bytes position in the OOB area. If 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)
 {
     struct mtd_info *master = mtd_get_master(mtd);
 
     memset(oobfree, 0, sizeof(*oobfree));
 
     if (!master || section < 0)
         return -EINVAL;
 
     if (!master->ooblayout || !master->ooblayout->free)
         return -ENOTSUPP;
 
     return master->ooblayout->free(master, section, oobfree);
 }
 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 function 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
  * @section: 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, ret;
 
     ret = mtd_ooblayout_find_region(mtd, start, &section,
                     &oobregion, iter);
 
     while (!ret) {
         int cnt;
 
         cnt = min_t(int, 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, ret;
 
     ret = mtd_ooblayout_find_region(mtd, start, &section,
                     &oobregion, iter);
 
     while (!ret) {
         int cnt;
 
         cnt = min_t(int, 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_set_databytes - set data bytes into the oob buffer
  * @mtd: mtd info structure
  * @databuf: 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_set_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_eccbytes - 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);
 
 /*
  * 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.
  */
 int mtd_get_fact_prot_info(struct mtd_info *mtd, size_t len, size_t *retlen,
                struct otp_info *buf)
 {
     struct mtd_info *master = mtd_get_master(mtd);
 
     if (!master->_get_fact_prot_info)
         return -EOPNOTSUPP;
     if (!len)
         return 0;
     return master->_get_fact_prot_info(master, len, retlen, buf);
 }
 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)
 {
     struct mtd_info *master = mtd_get_master(mtd);
 
     *retlen = 0;
     if (!master->_read_fact_prot_reg)
         return -EOPNOTSUPP;
     if (!len)
         return 0;
     return master->_read_fact_prot_reg(master, from, len, retlen, buf);
 }
 EXPORT_SYMBOL_GPL(mtd_read_fact_prot_reg);
 
 int mtd_get_user_prot_info(struct mtd_info *mtd, size_t len, size_t *retlen,
                struct otp_info *buf)
 {
     struct mtd_info *master = mtd_get_master(mtd);
 
     if (!master->_get_user_prot_info)
         return -EOPNOTSUPP;
     if (!len)
         return 0;
     return master->_get_user_prot_info(master, len, retlen, buf);
 }
 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)
 {
     struct mtd_info *master = mtd_get_master(mtd);
 
     *retlen = 0;
     if (!master->_read_user_prot_reg)
         return -EOPNOTSUPP;
     if (!len)
         return 0;
     return master->_read_user_prot_reg(master, 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, const u_char *buf)
 {
     struct mtd_info *master = mtd_get_master(mtd);
     int ret;
 
     *retlen = 0;
     if (!master->_write_user_prot_reg)
         return -EOPNOTSUPP;
     if (!len)
         return 0;
     ret = master->_write_user_prot_reg(master, 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;
 }
 EXPORT_SYMBOL_GPL(mtd_write_user_prot_reg);
 
 int mtd_lock_user_prot_reg(struct mtd_info *mtd, loff_t from, size_t len)
 {
     struct mtd_info *master = mtd_get_master(mtd);
 
     if (!master->_lock_user_prot_reg)
         return -EOPNOTSUPP;
     if (!len)
         return 0;
     return master->_lock_user_prot_reg(master, from, len);
 }
 EXPORT_SYMBOL_GPL(mtd_lock_user_prot_reg);
 
 int mtd_erase_user_prot_reg(struct mtd_info *mtd, loff_t from, size_t len)
 {
     struct mtd_info *master = mtd_get_master(mtd);
 
     if (!master->_erase_user_prot_reg)
         return -EOPNOTSUPP;
     if (!len)
         return 0;
     return master->_erase_user_prot_reg(master, from, len);
 }
 EXPORT_SYMBOL_GPL(mtd_erase_user_prot_reg);
 
 /* Chip-supported device locking */
 int mtd_lock(struct mtd_info *mtd, loff_t ofs, uint64_t len)
 {
     struct mtd_info *master = mtd_get_master(mtd);
 
     if (!master->_lock)
         return -EOPNOTSUPP;
     if (ofs < 0 || ofs >= mtd->size || len > mtd->size - ofs)
         return -EINVAL;
     if (!len)
         return 0;
 
     if (mtd->flags & MTD_SLC_ON_MLC_EMULATION) {
         ofs = (loff_t)mtd_div_by_eb(ofs, mtd) * master->erasesize;
         len = (u64)mtd_div_by_eb(len, mtd) * master->erasesize;
     }
 
     return master->_lock(master, mtd_get_master_ofs(mtd, ofs), len);
 }
 EXPORT_SYMBOL_GPL(mtd_lock);
 
 int mtd_unlock(struct mtd_info *mtd, loff_t ofs, uint64_t len)
 {
     struct mtd_info *master = mtd_get_master(mtd);
 
     if (!master->_unlock)
         return -EOPNOTSUPP;
     if (ofs < 0 || ofs >= mtd->size || len > mtd->size - ofs)
         return -EINVAL;
     if (!len)
         return 0;
 
     if (mtd->flags & MTD_SLC_ON_MLC_EMULATION) {
         ofs = (loff_t)mtd_div_by_eb(ofs, mtd) * master->erasesize;
         len = (u64)mtd_div_by_eb(len, mtd) * master->erasesize;
     }
 
     return master->_unlock(master, mtd_get_master_ofs(mtd, ofs), len);
 }
 EXPORT_SYMBOL_GPL(mtd_unlock);
 
 int mtd_is_locked(struct mtd_info *mtd, loff_t ofs, uint64_t len)
 {
     struct mtd_info *master = mtd_get_master(mtd);
 
     if (!master->_is_locked)
         return -EOPNOTSUPP;
     if (ofs < 0 || ofs >= mtd->size || len > mtd->size - ofs)
         return -EINVAL;
     if (!len)
         return 0;
 
     if (mtd->flags & MTD_SLC_ON_MLC_EMULATION) {
         ofs = (loff_t)mtd_div_by_eb(ofs, mtd) * master->erasesize;
         len = (u64)mtd_div_by_eb(len, mtd) * master->erasesize;
     }
 
     return master->_is_locked(master, mtd_get_master_ofs(mtd, ofs), len);
 }
 EXPORT_SYMBOL_GPL(mtd_is_locked);
 
 int mtd_block_isreserved(struct mtd_info *mtd, loff_t ofs)
 {
     struct mtd_info *master = mtd_get_master(mtd);
 
     if (ofs < 0 || ofs >= mtd->size)
         return -EINVAL;
     if (!master->_block_isreserved)
         return 0;
 
     if (mtd->flags & MTD_SLC_ON_MLC_EMULATION)
         ofs = (loff_t)mtd_div_by_eb(ofs, mtd) * master->erasesize;
 
     return master->_block_isreserved(master, mtd_get_master_ofs(mtd, ofs));
 }
 EXPORT_SYMBOL_GPL(mtd_block_isreserved);
 
 int mtd_block_isbad(struct mtd_info *mtd, loff_t ofs)
 {
     struct mtd_info *master = mtd_get_master(mtd);
 
     if (ofs < 0 || ofs >= mtd->size)
         return -EINVAL;
     if (!master->_block_isbad)
         return 0;
 
     if (mtd->flags & MTD_SLC_ON_MLC_EMULATION)
         ofs = (loff_t)mtd_div_by_eb(ofs, mtd) * master->erasesize;
 
     return master->_block_isbad(master, mtd_get_master_ofs(mtd, ofs));
 }
 EXPORT_SYMBOL_GPL(mtd_block_isbad);
 
 int mtd_block_markbad(struct mtd_info *mtd, loff_t ofs)
 {
     struct mtd_info *master = mtd_get_master(mtd);
     int ret;
 
     if (!master->_block_markbad)
         return -EOPNOTSUPP;
     if (ofs < 0 || ofs >= mtd->size)
         return -EINVAL;
     if (!(mtd->flags & MTD_WRITEABLE))
         return -EROFS;
 
     if (mtd->flags & MTD_SLC_ON_MLC_EMULATION)
         ofs = (loff_t)mtd_div_by_eb(ofs, mtd) * master->erasesize;
 
     ret = master->_block_markbad(master, mtd_get_master_ofs(mtd, ofs));
     if (ret)
         return ret;
 
     while (mtd->parent) {
         mtd->ecc_stats.badblocks++;
         mtd = mtd->parent;
     }
 
     return 0;
 }
 EXPORT_SYMBOL_GPL(mtd_block_markbad);
 
 /*
  * 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)
 {
     struct mtd_info *master = mtd_get_master(mtd);
 
     *retlen = 0;
     if (!(mtd->flags & MTD_WRITEABLE))
         return -EROFS;
 
     if (!master->_writev)
         return default_mtd_writev(mtd, vecs, count, to, retlen);
 
     return master->_writev(master, vecs, count,
                    mtd_get_master_ofs(mtd, 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_DIRECT_RECLAIM | __GFP_NORETRY;
     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);
 
 #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;
 }
 #endif /* CONFIG_PROC_FS */
 
 /*====================================================================*/
 /* Init code */
 
 static struct backing_dev_info * __init mtd_bdi_init(const char *name)
 {
     struct backing_dev_info *bdi;
     int ret;
 
     bdi = bdi_alloc(NUMA_NO_NODE);
     if (!bdi)
         return ERR_PTR(-ENOMEM);
     bdi->ra_pages = 0;
     bdi->io_pages = 0;
 
     /*
      * We put '-0' suffix to the name to get the same name format as we
      * used to get. Since this is called only once, we get a unique name. 
      */
     ret = bdi_register(bdi, "%.28s-0", name);
     if (ret)
         bdi_put(bdi);
 
     return ret ? ERR_PTR(ret) : bdi;
 }
 
 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;
 
     mtd_bdi = mtd_bdi_init("mtd");
     if (IS_ERR(mtd_bdi)) {
         ret = PTR_ERR(mtd_bdi);
         goto err_bdi;
     }
 
     proc_mtd = proc_create_single("mtd", 0, NULL, mtd_proc_show);
 
     ret = init_mtdchar();
     if (ret)
         goto out_procfs;
 
     dfs_dir_mtd = debugfs_create_dir("mtd", NULL);
     debugfs_create_bool("expert_analysis_mode", 0600, dfs_dir_mtd,
                 &mtd_expert_analysis_mode);
 
     return 0;
 
 out_procfs:
     if (proc_mtd)
         remove_proc_entry("mtd", NULL);
     bdi_put(mtd_bdi);
 err_bdi:
     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)
 {
     debugfs_remove_recursive(dfs_dir_mtd);
     cleanup_mtdchar();
     if (proc_mtd)
         remove_proc_entry("mtd", NULL);
     class_unregister(&mtd_class);
     bdi_unregister(mtd_bdi);
     bdi_put(mtd_bdi);
     idr_destroy(&mtd_idr);
 }
 
 module_init(init_mtd);
 module_exit(cleanup_mtd);
 
 MODULE_LICENSE("GPL");
 MODULE_AUTHOR("David Woodhouse <dwmw2@infradead.org>");
 MODULE_DESCRIPTION("Core MTD registration and access routines");

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