// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * Simple MTD partitioning layer
 *
 * Copyright © 2000 Nicolas Pitre <nico@fluxnic.net>
 * Copyright © 2002 Thomas Gleixner <gleixner@linutronix.de>
 * Copyright © 2000-2010 David Woodhouse <dwmw2@infradead.org>
 */

#include <linux/module.h>
#include <linux/types.h>
#include <linux/kernel.h>
#include <linux/slab.h>
#include <linux/list.h>
#include <linux/kmod.h>
#include <linux/mtd/mtd.h>
#include <linux/mtd/partitions.h>
#include <linux/err.h>
#include <linux/of.h>

#include "mtdcore.h"

/*
 * MTD methods which simply translate the effective address and pass through
 * to the _real_ device.
 */

static inline void free_partition(struct mtd_info *mtd)
{
        kfree(mtd->name);
        kfree(mtd);
}

static struct mtd_info *allocate_partition(struct mtd_info *parent,
                                           const struct mtd_partition *part,
                                           int partno, uint64_t cur_offset)
{
        struct mtd_info *master = mtd_get_master(parent);
        int wr_alignment = (parent->flags & MTD_NO_ERASE) ?
                           master->writesize : master->erasesize;
        u64 parent_size = mtd_is_partition(parent) ?
                          parent->part.size : parent->size;
        struct mtd_info *child;
        u32 remainder;
        char *name;
        u64 tmp;

        /* allocate the partition structure */
        child = kzalloc(sizeof(*child), GFP_KERNEL);
        name = kstrdup(part->name, GFP_KERNEL);
        if (!name || !child) {
                printk(KERN_ERR"memory allocation error while creating partitions for \"%s\"\n",
                       parent->name);
                kfree(name);
                kfree(child);
                return ERR_PTR(-ENOMEM);
        }

        /* set up the MTD object for this partition */
        child->type = parent->type;
        child->part.flags = parent->flags & ~part->mask_flags;
        child->part.flags |= part->add_flags;
        child->flags = child->part.flags;
        child->part.size = part->size;
        child->writesize = parent->writesize;
        child->writebufsize = parent->writebufsize;
        child->oobsize = parent->oobsize;
        child->oobavail = parent->oobavail;
        child->subpage_sft = parent->subpage_sft;

        child->name = name;
        child->owner = parent->owner;

        /* NOTE: Historically, we didn't arrange MTDs as a tree out of
         * concern for showing the same data in multiple partitions.
         * However, it is very useful to have the master node present,
         * so the MTD_PARTITIONED_MASTER option allows that. The master
         * will have device nodes etc only if this is set, so make the
         * parent conditional on that option. Note, this is a way to
         * distinguish between the parent and its partitions in sysfs.
         */
        child->dev.parent = IS_ENABLED(CONFIG_MTD_PARTITIONED_MASTER) || mtd_is_partition(parent) ?
                            &parent->dev : parent->dev.parent;
        child->dev.of_node = part->of_node;
        child->parent = parent;
        child->part.offset = part->offset;
        INIT_LIST_HEAD(&child->partitions);

        if (child->part.offset == MTDPART_OFS_APPEND)
                child->part.offset = cur_offset;
        if (child->part.offset == MTDPART_OFS_NXTBLK) {
                tmp = cur_offset;
                child->part.offset = cur_offset;
                remainder = do_div(tmp, wr_alignment);
                if (remainder) {
                        child->part.offset += wr_alignment - remainder;
                        printk(KERN_NOTICE "Moving partition %d: "
                               "0x%012llx -> 0x%012llx\n", partno,
                               (unsigned long long)cur_offset,
                               child->part.offset);
                }
        }
        if (child->part.offset == MTDPART_OFS_RETAIN) {
                child->part.offset = cur_offset;
                if (parent_size - child->part.offset >= child->part.size) {
                        child->part.size = parent_size - child->part.offset -
                                           child->part.size;
                } else {
                        printk(KERN_ERR "mtd partition \"%s\" doesn't have enough space: %#llx < %#llx, disabled\n",
                                part->name, parent_size - child->part.offset,
                                child->part.size);
                        /* register to preserve ordering */
                        goto out_register;
                }
        }
        if (child->part.size == MTDPART_SIZ_FULL)
                child->part.size = parent_size - child->part.offset;

        printk(KERN_NOTICE "0x%012llx-0x%012llx : \"%s\"\n",
               child->part.offset, child->part.offset + child->part.size,
               child->name);

        /* let's do some sanity checks */
        if (child->part.offset >= parent_size) {
                /* let's register it anyway to preserve ordering */
                child->part.offset = 0;
                child->part.size = 0;

                /* Initialize ->erasesize to make add_mtd_device() happy. */
                child->erasesize = parent->erasesize;
                printk(KERN_ERR"mtd: partition \"%s\" is out of reach -- disabled\n",
                        part->name);
                goto out_register;
        }
        if (child->part.offset + child->part.size > parent->size) {
                child->part.size = parent_size - child->part.offset;
                printk(KERN_WARNING"mtd: partition \"%s\" extends beyond the end of device \"%s\" -- size truncated to %#llx\n",
                        part->name, parent->name, child->part.size);
        }

        if (parent->numeraseregions > 1) {
                /* Deal with variable erase size stuff */
                int i, max = parent->numeraseregions;
                u64 end = child->part.offset + child->part.size;
                struct mtd_erase_region_info *regions = parent->eraseregions;

                /* Find the first erase regions which is part of this
                 * partition. */
                for (i = 0; i < max && regions[i].offset <= child->part.offset;
                     i++)
                        ;
                /* The loop searched for the region _behind_ the first one */
                if (i > 0)
                        i--;

                /* Pick biggest erasesize */
                for (; i < max && regions[i].offset < end; i++) {
                        if (child->erasesize < regions[i].erasesize)
                                child->erasesize = regions[i].erasesize;
                }
                BUG_ON(child->erasesize == 0);
        } else {
                /* Single erase size */
                child->erasesize = master->erasesize;
        }

        /*
         * Child erasesize might differ from the parent one if the parent
         * exposes several regions with different erasesize. Adjust
         * wr_alignment accordingly.
         */
        if (!(child->flags & MTD_NO_ERASE))
                wr_alignment = child->erasesize;

        tmp = mtd_get_master_ofs(child, 0);
        remainder = do_div(tmp, wr_alignment);
        if ((child->flags & MTD_WRITEABLE) && remainder) {
                /* Doesn't start on a boundary of major erase size */
                /* FIXME: Let it be writable if it is on a boundary of
                 * _minor_ erase size though */
                child->flags &= ~MTD_WRITEABLE;
                printk(KERN_WARNING"mtd: partition \"%s\" doesn't start on an erase/write block boundary -- force read-only\n",
                        part->name);
        }

        tmp = mtd_get_master_ofs(child, 0) + child->part.size;
        remainder = do_div(tmp, wr_alignment);
        if ((child->flags & MTD_WRITEABLE) && remainder) {
                child->flags &= ~MTD_WRITEABLE;
                printk(KERN_WARNING"mtd: partition \"%s\" doesn't end on an erase/write block -- force read-only\n",
                        part->name);
        }

        child->size = child->part.size;
        child->ecc_step_size = parent->ecc_step_size;
        child->ecc_strength = parent->ecc_strength;
        child->bitflip_threshold = parent->bitflip_threshold;

        if (master->_block_isbad) {
                uint64_t offs = 0;

                while (offs < child->part.size) {
                        if (mtd_block_isreserved(child, offs))
                                child->ecc_stats.bbtblocks++;
                        else if (mtd_block_isbad(child, offs))
                                child->ecc_stats.badblocks++;
                        offs += child->erasesize;
                }
        }

out_register:
        return child;
}

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

        return sysfs_emit(buf, "%lld\n", mtd->part.offset);
}
static DEVICE_ATTR_RO(offset);  /* mtd partition offset */

static const struct attribute *mtd_partition_attrs[] = {
        &dev_attr_offset.attr,
        NULL
};

static int mtd_add_partition_attrs(struct mtd_info *new)
{
        int ret = sysfs_create_files(&new->dev.kobj, mtd_partition_attrs);
        if (ret)
                printk(KERN_WARNING
                       "mtd: failed to create partition attrs, err=%d\n", ret);
        return ret;
}

int mtd_add_partition(struct mtd_info *parent, const char *name,
                      long long offset, long long length)
{
        struct mtd_info *master = mtd_get_master(parent);
        u64 parent_size = mtd_is_partition(parent) ?
                          parent->part.size : parent->size;
        struct mtd_partition part;
        struct mtd_info *child;
        int ret = 0;

        /* the direct offset is expected */
        if (offset == MTDPART_OFS_APPEND ||
            offset == MTDPART_OFS_NXTBLK)
                return -EINVAL;

        if (length == MTDPART_SIZ_FULL)
                length = parent_size - offset;

        if (length <= 0)
                return -EINVAL;

        memset(&part, 0, sizeof(part));
        part.name = name;
        part.size = length;
        part.offset = offset;

        child = allocate_partition(parent, &part, -1, offset);
        if (IS_ERR(child))
                return PTR_ERR(child);

        mutex_lock(&master->master.partitions_lock);
        list_add_tail(&child->part.node, &parent->partitions);
        mutex_unlock(&master->master.partitions_lock);

        ret = add_mtd_device(child);
        if (ret)
                goto err_remove_part;

        mtd_add_partition_attrs(child);

        return 0;

err_remove_part:
        mutex_lock(&master->master.partitions_lock);
        list_del(&child->part.node);
        mutex_unlock(&master->master.partitions_lock);

        free_partition(child);

        return ret;
}
EXPORT_SYMBOL_GPL(mtd_add_partition);

/**
 * __mtd_del_partition - delete MTD partition
 *
 * @mtd: MTD structure to be deleted
 *
 * This function must be called with the partitions mutex locked.
 */
static int __mtd_del_partition(struct mtd_info *mtd)
{
        struct mtd_info *child, *next;
        int err;

        list_for_each_entry_safe(child, next, &mtd->partitions, part.node) {
                err = __mtd_del_partition(child);
                if (err)
                        return err;
        }

        sysfs_remove_files(&mtd->dev.kobj, mtd_partition_attrs);

        err = del_mtd_device(mtd);
        if (err)
                return err;

        list_del(&child->part.node);
        free_partition(mtd);

        return 0;
}

/*
 * This function unregisters and destroy all slave MTD objects which are
 * attached to the given MTD object, recursively.
 */
static int __del_mtd_partitions(struct mtd_info *mtd)
{
        struct mtd_info *child, *next;
        LIST_HEAD(tmp_list);
        int ret, err = 0;

        list_for_each_entry_safe(child, next, &mtd->partitions, part.node) {
                if (mtd_has_partitions(child))
                        __del_mtd_partitions(child);

                pr_info("Deleting %s MTD partition\n", child->name);
                ret = del_mtd_device(child);
                if (ret < 0) {
                        pr_err("Error when deleting partition \"%s\" (%d)\n",
                               child->name, ret);
                        err = ret;
                        continue;
                }

                list_del(&child->part.node);
                free_partition(child);
        }

        return err;
}

int del_mtd_partitions(struct mtd_info *mtd)
{
        struct mtd_info *master = mtd_get_master(mtd);
        int ret;

        pr_info("Deleting MTD partitions on \"%s\":\n", mtd->name);

        mutex_lock(&master->master.partitions_lock);
        ret = __del_mtd_partitions(mtd);
        mutex_unlock(&master->master.partitions_lock);

        return ret;
}

int mtd_del_partition(struct mtd_info *mtd, int partno)
{
        struct mtd_info *child, *master = mtd_get_master(mtd);
        int ret = -EINVAL;

        mutex_lock(&master->master.partitions_lock);
        list_for_each_entry(child, &mtd->partitions, part.node) {
                if (child->index == partno) {
                        ret = __mtd_del_partition(child);
                        break;
                }
        }
        mutex_unlock(&master->master.partitions_lock);

        return ret;
}
EXPORT_SYMBOL_GPL(mtd_del_partition);

/*
 * This function, given a parent MTD object and a partition table, creates
 * and registers the child MTD objects which are bound to the parent according
 * to the partition definitions.
 *
 * For historical reasons, this function's caller only registers the parent
 * if the MTD_PARTITIONED_MASTER config option is set.
 */

int add_mtd_partitions(struct mtd_info *parent,
                       const struct mtd_partition *parts,
                       int nbparts)
{
        struct mtd_info *child, *master = mtd_get_master(parent);
        uint64_t cur_offset = 0;
        int i, ret;

        printk(KERN_NOTICE "Creating %d MTD partitions on \"%s\":\n",
               nbparts, parent->name);

        for (i = 0; i < nbparts; i++) {
                child = allocate_partition(parent, parts + i, i, cur_offset);
                if (IS_ERR(child)) {
                        ret = PTR_ERR(child);
                        goto err_del_partitions;
                }

                mutex_lock(&master->master.partitions_lock);
                list_add_tail(&child->part.node, &parent->partitions);
                mutex_unlock(&master->master.partitions_lock);

                ret = add_mtd_device(child);
                if (ret) {
                        mutex_lock(&master->master.partitions_lock);
                        list_del(&child->part.node);
                        mutex_unlock(&master->master.partitions_lock);

                        free_partition(child);
                        goto err_del_partitions;
                }

                mtd_add_partition_attrs(child);

                /* Look for subpartitions */
                parse_mtd_partitions(child, parts[i].types, NULL);

                cur_offset = child->part.offset + child->part.size;
        }

        return 0;

err_del_partitions:
        del_mtd_partitions(master);

        return ret;
}

static DEFINE_SPINLOCK(part_parser_lock);
static LIST_HEAD(part_parsers);

static struct mtd_part_parser *mtd_part_parser_get(const char *name)
{
        struct mtd_part_parser *p, *ret = NULL;

        spin_lock(&part_parser_lock);

        list_for_each_entry(p, &part_parsers, list)
                if (!strcmp(p->name, name) && try_module_get(p->owner)) {
                        ret = p;
                        break;
                }

        spin_unlock(&part_parser_lock);

        return ret;
}

static inline void mtd_part_parser_put(const struct mtd_part_parser *p)
{
        module_put(p->owner);
}

/*
 * Many partition parsers just expected the core to kfree() all their data in
 * one chunk. Do that by default.
 */
static void mtd_part_parser_cleanup_default(const struct mtd_partition *pparts,
                                            int nr_parts)
{
        kfree(pparts);
}

int __register_mtd_parser(struct mtd_part_parser *p, struct module *owner)
{
        p->owner = owner;

        if (!p->cleanup)
                p->cleanup = &mtd_part_parser_cleanup_default;

        spin_lock(&part_parser_lock);
        list_add(&p->list, &part_parsers);
        spin_unlock(&part_parser_lock);

        return 0;
}
EXPORT_SYMBOL_GPL(__register_mtd_parser);

void deregister_mtd_parser(struct mtd_part_parser *p)
{
        spin_lock(&part_parser_lock);
        list_del(&p->list);
        spin_unlock(&part_parser_lock);
}
EXPORT_SYMBOL_GPL(deregister_mtd_parser);

/*
 * Do not forget to update 'parse_mtd_partitions()' kerneldoc comment if you
 * are changing this array!
 */
static const char * const default_mtd_part_types[] = {
        "cmdlinepart",
        "ofpart",
        NULL
};

/* Check DT only when looking for subpartitions. */
static const char * const default_subpartition_types[] = {
        "ofpart",
        NULL
};

static int mtd_part_do_parse(struct mtd_part_parser *parser,
                             struct mtd_info *master,
                             struct mtd_partitions *pparts,
                             struct mtd_part_parser_data *data)
{
        int ret;

        ret = (*parser->parse_fn)(master, &pparts->parts, data);
        pr_debug("%s: parser %s: %i\n", master->name, parser->name, ret);
        if (ret <= 0)
                return ret;

        pr_notice("%d %s partitions found on MTD device %s\n", ret,
                  parser->name, master->name);

        pparts->nr_parts = ret;
        pparts->parser = parser;

        return ret;
}

/**
 * mtd_part_get_compatible_parser - find MTD parser by a compatible string
 *
 * @compat: compatible string describing partitions in a device tree
 *
 * MTD parsers can specify supported partitions by providing a table of
 * compatibility strings. This function finds a parser that advertises support
 * for a passed value of "compatible".
 */
static struct mtd_part_parser *mtd_part_get_compatible_parser(const char *compat)
{
        struct mtd_part_parser *p, *ret = NULL;

        spin_lock(&part_parser_lock);

        list_for_each_entry(p, &part_parsers, list) {
                const struct of_device_id *matches;

                matches = p->of_match_table;
                if (!matches)
                        continue;

                for (; matches->compatible[0]; matches++) {
                        if (!strcmp(matches->compatible, compat) &&
                            try_module_get(p->owner)) {
                                ret = p;
                                break;
                        }
                }

                if (ret)
                        break;
        }

        spin_unlock(&part_parser_lock);

        return ret;
}

static int mtd_part_of_parse(struct mtd_info *master,
                             struct mtd_partitions *pparts)
{
        struct mtd_part_parser *parser;
        struct device_node *np;
        struct property *prop;
        const char *compat;
        const char *fixed = "fixed-partitions";
        int ret, err = 0;

        np = mtd_get_of_node(master);
        if (mtd_is_partition(master))
                of_node_get(np);
        else
                np = of_get_child_by_name(np, "partitions");

        of_property_for_each_string(np, "compatible", prop, compat) {
                parser = mtd_part_get_compatible_parser(compat);
                if (!parser)
                        continue;
                ret = mtd_part_do_parse(parser, master, pparts, NULL);
                if (ret > 0) {
                        of_node_put(np);
                        return ret;
                }
                mtd_part_parser_put(parser);
                if (ret < 0 && !err)
                        err = ret;
        }
        of_node_put(np);

        /*
         * For backward compatibility we have to try the "fixed-partitions"
         * parser. It supports old DT format with partitions specified as a
         * direct subnodes of a flash device DT node without any compatibility
         * specified we could match.
         */
        parser = mtd_part_parser_get(fixed);
        if (!parser && !request_module("%s", fixed))
                parser = mtd_part_parser_get(fixed);
        if (parser) {
                ret = mtd_part_do_parse(parser, master, pparts, NULL);
                if (ret > 0)
                        return ret;
                mtd_part_parser_put(parser);
                if (ret < 0 && !err)
                        err = ret;
        }

        return err;
}

/**
 * parse_mtd_partitions - parse and register MTD partitions
 *
 * @master: the master partition (describes whole MTD device)
 * @types: names of partition parsers to try or %NULL
 * @data: MTD partition parser-specific data
 *
 * This function tries to find & register partitions on MTD device @master. It
 * uses MTD partition parsers, specified in @types. However, if @types is %NULL,
 * then the default list of parsers is used. The default list contains only the
 * "cmdlinepart" and "ofpart" parsers ATM.
 * Note: If there are more then one parser in @types, the kernel only takes the
 * partitions parsed out by the first parser.
 *
 * This function may return:
 * o a negative error code in case of failure
 * o number of found partitions otherwise
 */
int parse_mtd_partitions(struct mtd_info *master, const char *const *types,
                         struct mtd_part_parser_data *data)
{
        struct mtd_partitions pparts = { };
        struct mtd_part_parser *parser;
        int ret, err = 0;

        if (!types)
                types = mtd_is_partition(master) ? default_subpartition_types :
                        default_mtd_part_types;

        for ( ; *types; types++) {
                /*
                 * ofpart is a special type that means OF partitioning info
                 * should be used. It requires a bit different logic so it is
                 * handled in a separated function.
                 */
                if (!strcmp(*types, "ofpart")) {
                        ret = mtd_part_of_parse(master, &pparts);
                } else {
                        pr_debug("%s: parsing partitions %s\n", master->name,
                                 *types);
                        parser = mtd_part_parser_get(*types);
                        if (!parser && !request_module("%s", *types))
                                parser = mtd_part_parser_get(*types);
                        pr_debug("%s: got parser %s\n", master->name,
                                parser ? parser->name : NULL);
                        if (!parser)
                                continue;
                        ret = mtd_part_do_parse(parser, master, &pparts, data);
                        if (ret <= 0)
                                mtd_part_parser_put(parser);
                }
                /* Found partitions! */
                if (ret > 0) {
                        err = add_mtd_partitions(master, pparts.parts,
                                                 pparts.nr_parts);
                        mtd_part_parser_cleanup(&pparts);
                        return err ? err : pparts.nr_parts;
                }
                /*
                 * Stash the first error we see; only report it if no parser
                 * succeeds
                 */
                if (ret < 0 && !err)
                        err = ret;
        }
        return err;
}

void mtd_part_parser_cleanup(struct mtd_partitions *parts)
{
        const struct mtd_part_parser *parser;

        if (!parts)
                return;

        parser = parts->parser;
        if (parser) {
                if (parser->cleanup)
                        parser->cleanup(parts->parts, parts->nr_parts);

                mtd_part_parser_put(parser);
        }
}

/* Returns the size of the entire flash chip */
uint64_t mtd_get_device_size(const struct mtd_info *mtd)
{
        struct mtd_info *master = mtd_get_master((struct mtd_info *)mtd);

        return master->size;
}
EXPORT_SYMBOL_GPL(mtd_get_device_size);