mtdcore.c

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/*
 * Core registration and callback routines for MTD
 * drivers and users.
 *
 * Copyright © 1999-2010 David Woodhouse <[email protected]>
 * 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
 *
 */

#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/ptrace.h>
#include <linux/seq_file.h>
#include <linux/string.h>
#include <linux/timer.h>
#include <linux/major.h>
#include <linux/fs.h>
#include <linux/err.h>
#include <linux/ioctl.h>
#include <linux/init.h>
#include <linux/proc_fs.h>
#include <linux/idr.h>
#include <linux/backing-dev.h>
#include <linux/gfp.h>

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

#include "mtdcore.h"
/*
 * backing device capabilities for non-mappable devices (such as NAND flash)
 * - permits private mappings, copies are taken of the data
 */
static struct backing_dev_info mtd_bdi_unmappable = {
    .capabilities   = BDI_CAP_MAP_COPY,
};

/*
 * backing device capabilities for R/O mappable devices (such as ROM)
 * - permits private mappings, copies are taken of the data
 * - permits non-writable shared mappings
 */
static struct backing_dev_info mtd_bdi_ro_mappable = {
    .capabilities   = (BDI_CAP_MAP_COPY | BDI_CAP_MAP_DIRECT |
               BDI_CAP_EXEC_MAP | BDI_CAP_READ_MAP),
};

/*
 * backing device capabilities for writable mappable devices (such as RAM)
 * - permits private mappings, copies are taken of the data
 * - permits non-writable shared mappings
 */
static struct backing_dev_info mtd_bdi_rw_mappable = {
    .capabilities   = (BDI_CAP_MAP_COPY | BDI_CAP_MAP_DIRECT |
               BDI_CAP_EXEC_MAP | BDI_CAP_READ_MAP |
               BDI_CAP_WRITE_MAP),
};

static int mtd_cls_suspend(struct device *dev, pm_message_t state);
static int mtd_cls_resume(struct device *dev);

static struct class mtd_class = {
    .name = "mtd",
    .owner = THIS_MODULE,
    .suspend = mtd_cls_suspend,
    .resume = mtd_cls_resume,
};

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);


#if defined(CONFIG_MTD_CHAR) || defined(CONFIG_MTD_CHAR_MODULE)
#define MTD_DEVT(index) MKDEV(MTD_CHAR_MAJOR, (index)*2)
#else
#define MTD_DEVT(index) 0
#endif

/* REVISIT once MTD uses the driver model better, whoever allocates
 * the mtd_info will probably want to use the release() hook...
 */
static void mtd_release(struct device *dev)
{
    struct mtd_info __maybe_unused *mtd = dev_get_drvdata(dev);
    dev_t index = MTD_DEVT(mtd->index);

    /* remove /dev/mtdXro node if needed */
    if (index)
        device_destroy(&mtd_class, index + 1);
}

static int mtd_cls_suspend(struct device *dev, pm_message_t state)
{
    struct mtd_info *mtd = dev_get_drvdata(dev);

    return mtd ? mtd_suspend(mtd) : 0;
}

static int mtd_cls_resume(struct device *dev)
{
    struct mtd_info *mtd = dev_get_drvdata(dev);

    if (mtd)
        mtd_resume(mtd);
    return 0;
}

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

    switch (mtd->type) {
    case MTD_ABSENT:
        type = "absent";
        break;
    case MTD_RAM:
        type = "ram";
        break;
    case MTD_ROM:
        type = "rom";
        break;
    case MTD_NORFLASH:
        type = "nor";
        break;
    case MTD_NANDFLASH:
        type = "nand";
        break;
    case MTD_DATAFLASH:
        type = "dataflash";
        break;
    case MTD_UBIVOLUME:
        type = "ubi";
        break;
    default:
        type = "unknown";
    }

    return snprintf(buf, PAGE_SIZE, "%s\n", type);
}
static DEVICE_ATTR(type, S_IRUGO, mtd_type_show, NULL);

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

    return snprintf(buf, PAGE_SIZE, "0x%lx\n", (unsigned long)mtd->flags);

}
static DEVICE_ATTR(flags, S_IRUGO, mtd_flags_show, NULL);

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

    return snprintf(buf, PAGE_SIZE, "%llu\n",
        (unsigned long long)mtd->size);

}
static DEVICE_ATTR(size, S_IRUGO, mtd_size_show, NULL);

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

    return snprintf(buf, PAGE_SIZE, "%lu\n", (unsigned long)mtd->erasesize);

}
static DEVICE_ATTR(erasesize, S_IRUGO, mtd_erasesize_show, NULL);

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

    return snprintf(buf, PAGE_SIZE, "%lu\n", (unsigned long)mtd->writesize);

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

static ssize_t mtd_subpagesize_show(struct device *dev,
        struct device_attribute *attr, char *buf)
{
    struct mtd_info *mtd = dev_get_drvdata(dev);
    unsigned int subpagesize = mtd->writesize >> mtd->subpage_sft;

    return snprintf(buf, PAGE_SIZE, "%u\n", subpagesize);

}
static DEVICE_ATTR(subpagesize, S_IRUGO, mtd_subpagesize_show, NULL);

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

    return snprintf(buf, PAGE_SIZE, "%lu\n", (unsigned long)mtd->oobsize);

}
static DEVICE_ATTR(oobsize, S_IRUGO, mtd_oobsize_show, NULL);

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

    return snprintf(buf, PAGE_SIZE, "%u\n", mtd->numeraseregions);

}
static DEVICE_ATTR(numeraseregions, S_IRUGO, mtd_numeraseregions_show,
    NULL);

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

    return snprintf(buf, PAGE_SIZE, "%s\n", mtd->name);

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

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

    return snprintf(buf, PAGE_SIZE, "%u\n", mtd->ecc_strength);
}
static DEVICE_ATTR(ecc_strength, S_IRUGO, mtd_ecc_strength_show, NULL);

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

    return snprintf(buf, PAGE_SIZE, "%u\n", mtd->bitflip_threshold);
}

static ssize_t mtd_bitflip_threshold_store(struct device *dev,
                       struct device_attribute *attr,
                       const char *buf, size_t count)
{
    struct mtd_info *mtd = dev_get_drvdata(dev);
    unsigned int bitflip_threshold;
    int retval;

    retval = kstrtouint(buf, 0, &bitflip_threshold);
    if (retval)
        return retval;

    mtd->bitflip_threshold = bitflip_threshold;
    return count;
}
static DEVICE_ATTR(bitflip_threshold, S_IRUGO | S_IWUSR,
           mtd_bitflip_threshold_show,
           mtd_bitflip_threshold_store);

static struct attribute *mtd_attrs[] = {
    &dev_attr_type.attr,
    &dev_attr_flags.attr,
    &dev_attr_size.attr,
    &dev_attr_erasesize.attr,
    &dev_attr_writesize.attr,
    &dev_attr_subpagesize.attr,
    &dev_attr_oobsize.attr,
    &dev_attr_numeraseregions.attr,
    &dev_attr_name.attr,
    &dev_attr_ecc_strength.attr,
    &dev_attr_bitflip_threshold.attr,
    NULL,
};

static struct attribute_group mtd_group = {
    .attrs      = mtd_attrs,
};

static const struct attribute_group *mtd_groups[] = {
    &mtd_group,
    NULL,
};

static struct device_type mtd_devtype = {
    .name       = "mtd",
    .groups     = mtd_groups,
    .release    = mtd_release,
};

int add_mtd_device(struct mtd_info *mtd)
{
    struct mtd_notifier *not;
    int i, error;

    if (!mtd->backing_dev_info) {
        switch (mtd->type) {
        case MTD_RAM:
            mtd->backing_dev_info = &mtd_bdi_rw_mappable;
            break;
        case MTD_ROM:
            mtd->backing_dev_info = &mtd_bdi_ro_mappable;
            break;
        default:
            mtd->backing_dev_info = &mtd_bdi_unmappable;
            break;
        }
    }

    BUG_ON(mtd->writesize == 0);
    mutex_lock(&mtd_table_mutex);

    do {
        if (!idr_pre_get(&mtd_idr, GFP_KERNEL))
            goto fail_locked;
        error = idr_get_new(&mtd_idr, mtd, &i);
    } while (error == -EAGAIN);

    if (error)
        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 (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);
    }

    /* Caller should have set dev.parent to match the
     * physical device.
     */
    mtd->dev.type = &mtd_devtype;
    mtd->dev.class = &mtd_class;
    mtd->dev.devt = MTD_DEVT(i);
    dev_set_name(&mtd->dev, "mtd%d", i);
    dev_set_drvdata(&mtd->dev, mtd);
    if (device_register(&mtd->dev) != 0)
        goto fail_added;

    if (MTD_DEVT(i))
        device_create(&mtd_class, mtd->dev.parent,
                  MTD_DEVT(i) + 1,
                  NULL, "mtd%dro", i);

    pr_debug("mtd: Giving out device %d to %s\n", i, mtd->name);
    /* No need to get a refcount on the module containing
       the notifier, since we hold the mtd_table_mutex */
    list_for_each_entry(not, &mtd_notifiers, list)
        not->add(mtd);

    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_added:
    idr_remove(&mtd_idr, i);
fail_locked:
    mutex_unlock(&mtd_table_mutex);
    return 1;
}

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 {
        device_unregister(&mtd->dev);

        idr_remove(&mtd_idr, mtd->index);

        module_put(THIS_MODULE);
        ret = 0;
    }

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

int mtd_device_parse_register(struct mtd_info *mtd, const char **types,
                  struct mtd_part_parser_data *parser_data,
                  const struct mtd_partition *parts,
                  int nr_parts)
{
    int err;
    struct mtd_partition *real_parts;

    err = parse_mtd_partitions(mtd, types, &real_parts, parser_data);
    if (err <= 0 && nr_parts && parts) {
        real_parts = kmemdup(parts, sizeof(*parts) * nr_parts,
                     GFP_KERNEL);
        if (!real_parts)
            err = -ENOMEM;
        else
            err = nr_parts;
    }

    if (err > 0) {
        err = add_mtd_partitions(mtd, real_parts, err);
        kfree(real_parts);
    } else if (err == 0) {
        err = add_mtd_device(mtd);
        if (err == 1)
            err = -ENODEV;
    }

    return err;
}
EXPORT_SYMBOL_GPL(mtd_device_parse_register);

int mtd_device_unregister(struct mtd_info *master)
{
    int err;

    err = del_mtd_partitions(master);
    if (err)
        return err;

    if (!device_is_registered(&master->dev))
        return 0;

    return del_mtd_device(master);
}
EXPORT_SYMBOL_GPL(mtd_device_unregister);

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);

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);

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)
{
    int err;

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

    if (mtd->_get_device) {
        err = mtd->_get_device(mtd);

        if (err) {
            module_put(mtd->owner);
            return err;
        }
    }
    mtd->usecount++;
    return 0;
}
EXPORT_SYMBOL_GPL(__get_mtd_device);

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)
{
    --mtd->usecount;
    BUG_ON(mtd->usecount < 0);

    if (mtd->_put_device)
        mtd->_put_device(mtd);

    module_put(mtd->owner);
}
EXPORT_SYMBOL_GPL(__put_mtd_device);

/*
 * Erase is an asynchronous operation.  Device drivers are supposed
 * to call instr->callback() whenever the operation completes, even
 * if it completes with a failure.
 * 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)
{
    if (instr->addr > mtd->size || instr->len > mtd->size - instr->addr)
        return -EINVAL;
    if (!(mtd->flags & MTD_WRITEABLE))
        return -EROFS;
    instr->fail_addr = MTD_FAIL_ADDR_UNKNOWN;
    if (!instr->len) {
        instr->state = MTD_ERASE_DONE;
        mtd_erase_callback(instr);
        return 0;
    }
    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;
    *virt = NULL;
    if (phys)
        *phys = 0;
    if (!mtd->_point)
        return -EOPNOTSUPP;
    if (from < 0 || from > mtd->size || len > mtd->size - from)
        return -EINVAL;
    if (!len)
        return 0;
    return mtd->_point(mtd, from, len, retlen, virt, phys);
}
EXPORT_SYMBOL_GPL(mtd_point);

/* We probably shouldn't allow XIP if the unpoint isn't a NULL */
int mtd_unpoint(struct mtd_info *mtd, loff_t from, size_t len)
{
    if (!mtd->_point)
        return -EOPNOTSUPP;
    if (from < 0 || from > mtd->size || len > mtd->size - from)
        return -EINVAL;
    if (!len)
        return 0;
    return mtd->_unpoint(mtd, from, len);
}
EXPORT_SYMBOL_GPL(mtd_unpoint);

/*
 * Allow NOMMU mmap() to directly map the device (if not NULL)
 * - return the address to which the offset maps
 * - return -ENOSYS to indicate refusal to do the mapping
 */
unsigned long mtd_get_unmapped_area(struct mtd_info *mtd, unsigned long len,
                    unsigned long offset, unsigned long flags)
{
    if (!mtd->_get_unmapped_area)
        return -EOPNOTSUPP;
    if (offset > mtd->size || len > mtd->size - offset)
        return -EINVAL;
    return mtd->_get_unmapped_area(mtd, len, offset, flags);
}
EXPORT_SYMBOL_GPL(mtd_get_unmapped_area);

int mtd_read(struct mtd_info *mtd, loff_t from, size_t len, size_t *retlen,
         u_char *buf)
{
    int ret_code;
    *retlen = 0;
    if (from < 0 || from > mtd->size || len > mtd->size - from)
        return -EINVAL;
    if (!len)
        return 0;

    /*
     * 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;
}
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;
    if (to < 0 || to > mtd->size || len > mtd->size - to)
        return -EINVAL;
    if (!mtd->_write || !(mtd->flags & MTD_WRITEABLE))
        return -EROFS;
    if (!len)
        return 0;
    return mtd->_write(mtd, to, len, retlen, buf);
}
EXPORT_SYMBOL_GPL(mtd_write);

/*
 * In blackbox flight recorder like scenarios we want to make successful writes
 * 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;
    if (to < 0 || to > mtd->size || len > mtd->size - to)
        return -EINVAL;
    if (!(mtd->flags & MTD_WRITEABLE))
        return -EROFS;
    if (!len)
        return 0;
    return mtd->_panic_write(mtd, to, len, retlen, buf);
}
EXPORT_SYMBOL_GPL(mtd_panic_write);

int mtd_read_oob(struct mtd_info *mtd, loff_t from, struct mtd_oob_ops *ops)
{
    int ret_code;
    ops->retlen = ops->oobretlen = 0;
    if (!mtd->_read_oob)
        return -EOPNOTSUPP;
    /*
     * In cases where ops->datbuf != NULL, mtd->_read_oob() has semantics
     * similar to mtd->_read(), returning a non-negative integer
     * representing max bitflips. In other cases, mtd->_read_oob() may
     * return -EUCLEAN. In all cases, perform similar logic to mtd_read().
     */
    ret_code = mtd->_read_oob(mtd, from, ops);
    if (unlikely(ret_code < 0))
        return ret_code;
    if (mtd->ecc_strength == 0)
        return 0;   /* device lacks ecc */
    return ret_code >= mtd->bitflip_threshold ? -EUCLEAN : 0;
}
EXPORT_SYMBOL_GPL(mtd_read_oob);

/*
 * Method to access the protection register area, present in some flash
 * 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, struct otp_info *buf,
               size_t len)
{
    if (!mtd->_get_fact_prot_info)
        return -EOPNOTSUPP;
    if (!len)
        return 0;
    return mtd->_get_fact_prot_info(mtd, buf, len);
}
EXPORT_SYMBOL_GPL(mtd_get_fact_prot_info);

int mtd_read_fact_prot_reg(struct mtd_info *mtd, loff_t from, size_t len,
               size_t *retlen, u_char *buf)
{
    *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);

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

int mtd_read_user_prot_reg(struct mtd_info *mtd, loff_t from, size_t len,
               size_t *retlen, u_char *buf)
{
    *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)
{
    *retlen = 0;
    if (!mtd->_write_user_prot_reg)
        return -EOPNOTSUPP;
    if (!len)
        return 0;
    return mtd->_write_user_prot_reg(mtd, to, len, retlen, buf);
}
EXPORT_SYMBOL_GPL(mtd_write_user_prot_reg);

int mtd_lock_user_prot_reg(struct mtd_info *mtd, loff_t from, size_t len)
{
    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);

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

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

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

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

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

void *mtd_kmalloc_up_to(const struct mtd_info *mtd, size_t *size)
{
    gfp_t flags = __GFP_NOWARN | __GFP_WAIT |
               __GFP_NORETRY | __GFP_NO_KSWAPD;
    size_t min_alloc = max_t(size_t, mtd->writesize, PAGE_SIZE);
    void *kbuf;

    *size = min_t(size_t, *size, KMALLOC_MAX_SIZE);

    while (*size > min_alloc) {
        kbuf = kmalloc(*size, flags);
        if (kbuf)
            return kbuf;

        *size >>= 1;
        *size = ALIGN(*size, mtd->writesize);
    }

    /*
     * For the last resort allocation allow 'kmalloc()' to do all sorts of
     * things (write-back, dropping caches, etc) by using GFP_KERNEL.
     */
    return kmalloc(*size, GFP_KERNEL);
}
EXPORT_SYMBOL_GPL(mtd_kmalloc_up_to);

#ifdef CONFIG_PROC_FS

/*====================================================================*/
/* Support for /proc/mtd */

static struct proc_dir_entry *proc_mtd;

static int mtd_proc_show(struct seq_file *m, void *v)
{
    struct mtd_info *mtd;

    seq_puts(m, "dev:    size   erasesize  name\n");
    mutex_lock(&mtd_table_mutex);
    mtd_for_each_device(mtd) {
        seq_printf(m, "mtd%d: %8.8llx %8.8x \"%s\"\n",
               mtd->index, (unsigned long long)mtd->size,
               mtd->erasesize, mtd->name);
    }
    mutex_unlock(&mtd_table_mutex);
    return 0;
}

static int mtd_proc_open(struct inode *inode, struct file *file)
{
    return single_open(file, mtd_proc_show, NULL);
}

static const struct file_operations mtd_proc_ops = {
    .open       = mtd_proc_open,
    .read       = seq_read,
    .llseek     = seq_lseek,
    .release    = single_release,
};
#endif /* CONFIG_PROC_FS */

/*====================================================================*/
/* Init code */

static int __init mtd_bdi_init(struct backing_dev_info *bdi, const char *name)
{
    int ret;

    ret = bdi_init(bdi);
    if (!ret)
        ret = bdi_register(bdi, NULL, name);

    if (ret)
        bdi_destroy(bdi);

    return ret;
}

static int __init init_mtd(void)
{
    int ret;

    ret = class_register(&mtd_class);
    if (ret)
        goto err_reg;

    ret = mtd_bdi_init(&mtd_bdi_unmappable, "mtd-unmap");
    if (ret)
        goto err_bdi1;

    ret = mtd_bdi_init(&mtd_bdi_ro_mappable, "mtd-romap");
    if (ret)
        goto err_bdi2;

    ret = mtd_bdi_init(&mtd_bdi_rw_mappable, "mtd-rwmap");
    if (ret)
        goto err_bdi3;

#ifdef CONFIG_PROC_FS
    proc_mtd = proc_create("mtd", 0, NULL, &mtd_proc_ops);
#endif /* CONFIG_PROC_FS */
    return 0;

err_bdi3:
    bdi_destroy(&mtd_bdi_ro_mappable);
err_bdi2:
    bdi_destroy(&mtd_bdi_unmappable);
err_bdi1:
    class_unregister(&mtd_class);
err_reg:
    pr_err("Error registering mtd class or bdi: %d\n", ret);
    return ret;
}

static void __exit cleanup_mtd(void)
{
#ifdef CONFIG_PROC_FS
    if (proc_mtd)
        remove_proc_entry( "mtd", NULL);
#endif /* CONFIG_PROC_FS */
    class_unregister(&mtd_class);
    bdi_destroy(&mtd_bdi_unmappable);
    bdi_destroy(&mtd_bdi_ro_mappable);
    bdi_destroy(&mtd_bdi_rw_mappable);
}

module_init(init_mtd);
module_exit(cleanup_mtd);

MODULE_LICENSE("GPL");
MODULE_AUTHOR("David Woodhouse <[email protected]>");
MODULE_DESCRIPTION("Core MTD registration and access routines");