// SPDX-License-Identifier: GPL-2.0-only
/*
 * Copyright(c) 2013-2016 Intel Corporation. All rights reserved.
 */
#include <linux/memremap.h>
#include <linux/blkdev.h>
#include <linux/device.h>
#include <linux/genhd.h>
#include <linux/sizes.h>
#include <linux/slab.h>
#include <linux/fs.h>
#include <linux/mm.h>
#include "nd-core.h"
#include "pfn.h"
#include "nd.h"

static void nd_pfn_release(struct device *dev)
{
        struct nd_region *nd_region = to_nd_region(dev->parent);
        struct nd_pfn *nd_pfn = to_nd_pfn(dev);

        dev_dbg(dev, "trace\n");
        nd_detach_ndns(&nd_pfn->dev, &nd_pfn->ndns);
        ida_simple_remove(&nd_region->pfn_ida, nd_pfn->id);
        kfree(nd_pfn->uuid);
        kfree(nd_pfn);
}

struct nd_pfn *to_nd_pfn(struct device *dev)
{
        struct nd_pfn *nd_pfn = container_of(dev, struct nd_pfn, dev);

        WARN_ON(!is_nd_pfn(dev));
        return nd_pfn;
}
EXPORT_SYMBOL(to_nd_pfn);

static ssize_t mode_show(struct device *dev,
                struct device_attribute *attr, char *buf)
{
        struct nd_pfn *nd_pfn = to_nd_pfn_safe(dev);

        switch (nd_pfn->mode) {
        case PFN_MODE_RAM:
                return sprintf(buf, "ram\n");
        case PFN_MODE_PMEM:
                return sprintf(buf, "pmem\n");
        default:
                return sprintf(buf, "none\n");
        }
}

static ssize_t mode_store(struct device *dev,
                struct device_attribute *attr, const char *buf, size_t len)
{
        struct nd_pfn *nd_pfn = to_nd_pfn_safe(dev);
        ssize_t rc = 0;

        nd_device_lock(dev);
        nvdimm_bus_lock(dev);
        if (dev->driver)
                rc = -EBUSY;
        else {
                size_t n = len - 1;

                if (strncmp(buf, "pmem\n", n) == 0
                                || strncmp(buf, "pmem", n) == 0) {
                        nd_pfn->mode = PFN_MODE_PMEM;
                } else if (strncmp(buf, "ram\n", n) == 0
                                || strncmp(buf, "ram", n) == 0)
                        nd_pfn->mode = PFN_MODE_RAM;
                else if (strncmp(buf, "none\n", n) == 0
                                || strncmp(buf, "none", n) == 0)
                        nd_pfn->mode = PFN_MODE_NONE;
                else
                        rc = -EINVAL;
        }
        dev_dbg(dev, "result: %zd wrote: %s%s", rc, buf,
                        buf[len - 1] == '\n' ? "" : "\n");
        nvdimm_bus_unlock(dev);
        nd_device_unlock(dev);

        return rc ? rc : len;
}
static DEVICE_ATTR_RW(mode);

static ssize_t align_show(struct device *dev,
                struct device_attribute *attr, char *buf)
{
        struct nd_pfn *nd_pfn = to_nd_pfn_safe(dev);

        return sprintf(buf, "%ld\n", nd_pfn->align);
}

static unsigned long *nd_pfn_supported_alignments(unsigned long *alignments)
{

        alignments[0] = PAGE_SIZE;

        if (has_transparent_hugepage()) {
                alignments[1] = HPAGE_PMD_SIZE;
                if (IS_ENABLED(CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD))
                        alignments[2] = HPAGE_PUD_SIZE;
        }

        return alignments;
}

/*
 * Use pmd mapping if supported as default alignment
 */
static unsigned long nd_pfn_default_alignment(void)
{

        if (has_transparent_hugepage())
                return HPAGE_PMD_SIZE;
        return PAGE_SIZE;
}

static ssize_t align_store(struct device *dev,
                struct device_attribute *attr, const char *buf, size_t len)
{
        struct nd_pfn *nd_pfn = to_nd_pfn_safe(dev);
        unsigned long aligns[MAX_NVDIMM_ALIGN] = { [0] = 0, };
        ssize_t rc;

        nd_device_lock(dev);
        nvdimm_bus_lock(dev);
        rc = nd_size_select_store(dev, buf, &nd_pfn->align,
                        nd_pfn_supported_alignments(aligns));
        dev_dbg(dev, "result: %zd wrote: %s%s", rc, buf,
                        buf[len - 1] == '\n' ? "" : "\n");
        nvdimm_bus_unlock(dev);
        nd_device_unlock(dev);

        return rc ? rc : len;
}
static DEVICE_ATTR_RW(align);

static ssize_t uuid_show(struct device *dev,
                struct device_attribute *attr, char *buf)
{
        struct nd_pfn *nd_pfn = to_nd_pfn_safe(dev);

        if (nd_pfn->uuid)
                return sprintf(buf, "%pUb\n", nd_pfn->uuid);
        return sprintf(buf, "\n");
}

static ssize_t uuid_store(struct device *dev,
                struct device_attribute *attr, const char *buf, size_t len)
{
        struct nd_pfn *nd_pfn = to_nd_pfn_safe(dev);
        ssize_t rc;

        nd_device_lock(dev);
        rc = nd_uuid_store(dev, &nd_pfn->uuid, buf, len);
        dev_dbg(dev, "result: %zd wrote: %s%s", rc, buf,
                        buf[len - 1] == '\n' ? "" : "\n");
        nd_device_unlock(dev);

        return rc ? rc : len;
}
static DEVICE_ATTR_RW(uuid);

static ssize_t namespace_show(struct device *dev,
                struct device_attribute *attr, char *buf)
{
        struct nd_pfn *nd_pfn = to_nd_pfn_safe(dev);
        ssize_t rc;

        nvdimm_bus_lock(dev);
        rc = sprintf(buf, "%s\n", nd_pfn->ndns
                        ? dev_name(&nd_pfn->ndns->dev) : "");
        nvdimm_bus_unlock(dev);
        return rc;
}

static ssize_t namespace_store(struct device *dev,
                struct device_attribute *attr, const char *buf, size_t len)
{
        struct nd_pfn *nd_pfn = to_nd_pfn_safe(dev);
        ssize_t rc;

        nd_device_lock(dev);
        nvdimm_bus_lock(dev);
        rc = nd_namespace_store(dev, &nd_pfn->ndns, buf, len);
        dev_dbg(dev, "result: %zd wrote: %s%s", rc, buf,
                        buf[len - 1] == '\n' ? "" : "\n");
        nvdimm_bus_unlock(dev);
        nd_device_unlock(dev);

        return rc;
}
static DEVICE_ATTR_RW(namespace);

static ssize_t resource_show(struct device *dev,
                struct device_attribute *attr, char *buf)
{
        struct nd_pfn *nd_pfn = to_nd_pfn_safe(dev);
        ssize_t rc;

        nd_device_lock(dev);
        if (dev->driver) {
                struct nd_pfn_sb *pfn_sb = nd_pfn->pfn_sb;
                u64 offset = __le64_to_cpu(pfn_sb->dataoff);
                struct nd_namespace_common *ndns = nd_pfn->ndns;
                u32 start_pad = __le32_to_cpu(pfn_sb->start_pad);
                struct nd_namespace_io *nsio = to_nd_namespace_io(&ndns->dev);

                rc = sprintf(buf, "%#llx\n", (unsigned long long) nsio->res.start
                                + start_pad + offset);
        } else {
                /* no address to convey if the pfn instance is disabled */
                rc = -ENXIO;
        }
        nd_device_unlock(dev);

        return rc;
}
static DEVICE_ATTR(resource, 0400, resource_show, NULL);

static ssize_t size_show(struct device *dev,
                struct device_attribute *attr, char *buf)
{
        struct nd_pfn *nd_pfn = to_nd_pfn_safe(dev);
        ssize_t rc;

        nd_device_lock(dev);
        if (dev->driver) {
                struct nd_pfn_sb *pfn_sb = nd_pfn->pfn_sb;
                u64 offset = __le64_to_cpu(pfn_sb->dataoff);
                struct nd_namespace_common *ndns = nd_pfn->ndns;
                u32 start_pad = __le32_to_cpu(pfn_sb->start_pad);
                u32 end_trunc = __le32_to_cpu(pfn_sb->end_trunc);
                struct nd_namespace_io *nsio = to_nd_namespace_io(&ndns->dev);

                rc = sprintf(buf, "%llu\n", (unsigned long long)
                                resource_size(&nsio->res) - start_pad
                                - end_trunc - offset);
        } else {
                /* no size to convey if the pfn instance is disabled */
                rc = -ENXIO;
        }
        nd_device_unlock(dev);

        return rc;
}
static DEVICE_ATTR_RO(size);

static ssize_t supported_alignments_show(struct device *dev,
                struct device_attribute *attr, char *buf)
{
        unsigned long aligns[MAX_NVDIMM_ALIGN] = { [0] = 0, };

        return nd_size_select_show(0,
                        nd_pfn_supported_alignments(aligns), buf);
}
static DEVICE_ATTR_RO(supported_alignments);

static struct attribute *nd_pfn_attributes[] = {
        &dev_attr_mode.attr,
        &dev_attr_namespace.attr,
        &dev_attr_uuid.attr,
        &dev_attr_align.attr,
        &dev_attr_resource.attr,
        &dev_attr_size.attr,
        &dev_attr_supported_alignments.attr,
        NULL,
};

static struct attribute_group nd_pfn_attribute_group = {
        .attrs = nd_pfn_attributes,
};

const struct attribute_group *nd_pfn_attribute_groups[] = {
        &nd_pfn_attribute_group,
        &nd_device_attribute_group,
        &nd_numa_attribute_group,
        NULL,
};

static const struct device_type nd_pfn_device_type = {
        .name = "nd_pfn",
        .release = nd_pfn_release,
        .groups = nd_pfn_attribute_groups,
};

bool is_nd_pfn(struct device *dev)
{
        return dev ? dev->type == &nd_pfn_device_type : false;
}
EXPORT_SYMBOL(is_nd_pfn);

struct device *nd_pfn_devinit(struct nd_pfn *nd_pfn,
                struct nd_namespace_common *ndns)
{
        struct device *dev;

        if (!nd_pfn)
                return NULL;

        nd_pfn->mode = PFN_MODE_NONE;
        nd_pfn->align = nd_pfn_default_alignment();
        dev = &nd_pfn->dev;
        device_initialize(&nd_pfn->dev);
        if (ndns && !__nd_attach_ndns(&nd_pfn->dev, ndns, &nd_pfn->ndns)) {
                dev_dbg(&ndns->dev, "failed, already claimed by %s\n",
                                dev_name(ndns->claim));
                put_device(dev);
                return NULL;
        }
        return dev;
}

static struct nd_pfn *nd_pfn_alloc(struct nd_region *nd_region)
{
        struct nd_pfn *nd_pfn;
        struct device *dev;

        nd_pfn = kzalloc(sizeof(*nd_pfn), GFP_KERNEL);
        if (!nd_pfn)
                return NULL;

        nd_pfn->id = ida_simple_get(&nd_region->pfn_ida, 0, 0, GFP_KERNEL);
        if (nd_pfn->id < 0) {
                kfree(nd_pfn);
                return NULL;
        }

        dev = &nd_pfn->dev;
        dev_set_name(dev, "pfn%d.%d", nd_region->id, nd_pfn->id);
        dev->type = &nd_pfn_device_type;
        dev->parent = &nd_region->dev;

        return nd_pfn;
}

struct device *nd_pfn_create(struct nd_region *nd_region)
{
        struct nd_pfn *nd_pfn;
        struct device *dev;

        if (!is_memory(&nd_region->dev))
                return NULL;

        nd_pfn = nd_pfn_alloc(nd_region);
        dev = nd_pfn_devinit(nd_pfn, NULL);

        __nd_device_register(dev);
        return dev;
}

/*
 * nd_pfn_clear_memmap_errors() clears any errors in the volatile memmap
 * space associated with the namespace. If the memmap is set to DRAM, then
 * this is a no-op. Since the memmap area is freshly initialized during
 * probe, we have an opportunity to clear any badblocks in this area.
 */
static int nd_pfn_clear_memmap_errors(struct nd_pfn *nd_pfn)
{
        struct nd_region *nd_region = to_nd_region(nd_pfn->dev.parent);
        struct nd_namespace_common *ndns = nd_pfn->ndns;
        void *zero_page = page_address(ZERO_PAGE(0));
        struct nd_pfn_sb *pfn_sb = nd_pfn->pfn_sb;
        int num_bad, meta_num, rc, bb_present;
        sector_t first_bad, meta_start;
        struct nd_namespace_io *nsio;

        if (nd_pfn->mode != PFN_MODE_PMEM)
                return 0;

        nsio = to_nd_namespace_io(&ndns->dev);
        meta_start = (SZ_4K + sizeof(*pfn_sb)) >> 9;
        meta_num = (le64_to_cpu(pfn_sb->dataoff) >> 9) - meta_start;

        /*
         * re-enable the namespace with correct size so that we can access
         * the device memmap area.
         */
        devm_namespace_disable(&nd_pfn->dev, ndns);
        rc = devm_namespace_enable(&nd_pfn->dev, ndns, le64_to_cpu(pfn_sb->dataoff));
        if (rc)
                return rc;

        do {
                unsigned long zero_len;
                u64 nsoff;

                bb_present = badblocks_check(&nd_region->bb, meta_start,
                                meta_num, &first_bad, &num_bad);
                if (bb_present) {
                        dev_dbg(&nd_pfn->dev, "meta: %x badblocks at %llx\n",
                                        num_bad, first_bad);
                        nsoff = ALIGN_DOWN((nd_region->ndr_start
                                        + (first_bad << 9)) - nsio->res.start,
                                        PAGE_SIZE);
                        zero_len = ALIGN(num_bad << 9, PAGE_SIZE);
                        while (zero_len) {
                                unsigned long chunk = min(zero_len, PAGE_SIZE);

                                rc = nvdimm_write_bytes(ndns, nsoff, zero_page,
                                                        chunk, 0);
                                if (rc)
                                        break;

                                zero_len -= chunk;
                                nsoff += chunk;
                        }
                        if (rc) {
                                dev_err(&nd_pfn->dev,
                                        "error clearing %x badblocks at %llx\n",
                                        num_bad, first_bad);
                                return rc;
                        }
                }
        } while (bb_present);

        return 0;
}

static bool nd_supported_alignment(unsigned long align)
{
        int i;
        unsigned long supported[MAX_NVDIMM_ALIGN] = { [0] = 0, };

        if (align == 0)
                return false;

        nd_pfn_supported_alignments(supported);
        for (i = 0; supported[i]; i++)
                if (align == supported[i])
                        return true;
        return false;
}

/**
 * nd_pfn_validate - read and validate info-block
 * @nd_pfn: fsdax namespace runtime state / properties
 * @sig: 'devdax' or 'fsdax' signature
 *
 * Upon return the info-block buffer contents (->pfn_sb) are
 * indeterminate when validation fails, and a coherent info-block
 * otherwise.
 */
int nd_pfn_validate(struct nd_pfn *nd_pfn, const char *sig)
{
        u64 checksum, offset;
        enum nd_pfn_mode mode;
        struct nd_namespace_io *nsio;
        unsigned long align, start_pad;
        struct nd_pfn_sb *pfn_sb = nd_pfn->pfn_sb;
        struct nd_namespace_common *ndns = nd_pfn->ndns;
        const u8 *parent_uuid = nd_dev_to_uuid(&ndns->dev);

        if (!pfn_sb || !ndns)
                return -ENODEV;

        if (!is_memory(nd_pfn->dev.parent))
                return -ENODEV;

        if (nvdimm_read_bytes(ndns, SZ_4K, pfn_sb, sizeof(*pfn_sb), 0))
                return -ENXIO;

        if (memcmp(pfn_sb->signature, sig, PFN_SIG_LEN) != 0)
                return -ENODEV;

        checksum = le64_to_cpu(pfn_sb->checksum);
        pfn_sb->checksum = 0;
        if (checksum != nd_sb_checksum((struct nd_gen_sb *) pfn_sb))
                return -ENODEV;
        pfn_sb->checksum = cpu_to_le64(checksum);

        if (memcmp(pfn_sb->parent_uuid, parent_uuid, 16) != 0)
                return -ENODEV;

        if (__le16_to_cpu(pfn_sb->version_minor) < 1) {
                pfn_sb->start_pad = 0;
                pfn_sb->end_trunc = 0;
        }

        if (__le16_to_cpu(pfn_sb->version_minor) < 2)
                pfn_sb->align = 0;

        if (__le16_to_cpu(pfn_sb->version_minor) < 4) {
                pfn_sb->page_struct_size = cpu_to_le16(64);
                pfn_sb->page_size = cpu_to_le32(PAGE_SIZE);
        }

        switch (le32_to_cpu(pfn_sb->mode)) {
        case PFN_MODE_RAM:
        case PFN_MODE_PMEM:
                break;
        default:
                return -ENXIO;
        }

        align = le32_to_cpu(pfn_sb->align);
        offset = le64_to_cpu(pfn_sb->dataoff);
        start_pad = le32_to_cpu(pfn_sb->start_pad);
        if (align == 0)
                align = 1UL << ilog2(offset);
        mode = le32_to_cpu(pfn_sb->mode);

        if ((le32_to_cpu(pfn_sb->page_size) > PAGE_SIZE) &&
                        (mode == PFN_MODE_PMEM)) {
                dev_err(&nd_pfn->dev,
                                "init failed, page size mismatch %d\n",
                                le32_to_cpu(pfn_sb->page_size));
                return -EOPNOTSUPP;
        }

        if ((le16_to_cpu(pfn_sb->page_struct_size) < sizeof(struct page)) &&
                        (mode == PFN_MODE_PMEM)) {
                dev_err(&nd_pfn->dev,
                                "init failed, struct page size mismatch %d\n",
                                le16_to_cpu(pfn_sb->page_struct_size));
                return -EOPNOTSUPP;
        }

        /*
         * Check whether the we support the alignment. For Dax if the
         * superblock alignment is not matching, we won't initialize
         * the device.
         */
        if (!nd_supported_alignment(align) &&
                        !memcmp(pfn_sb->signature, DAX_SIG, PFN_SIG_LEN)) {
                dev_err(&nd_pfn->dev, "init failed, alignment mismatch: "
                                "%ld:%ld\n", nd_pfn->align, align);
                return -EOPNOTSUPP;
        }

        if (!nd_pfn->uuid) {
                /*
                 * When probing a namepace via nd_pfn_probe() the uuid
                 * is NULL (see: nd_pfn_devinit()) we init settings from
                 * pfn_sb
                 */
                nd_pfn->uuid = kmemdup(pfn_sb->uuid, 16, GFP_KERNEL);
                if (!nd_pfn->uuid)
                        return -ENOMEM;
                nd_pfn->align = align;
                nd_pfn->mode = mode;
        } else {
                /*
                 * When probing a pfn / dax instance we validate the
                 * live settings against the pfn_sb
                 */
                if (memcmp(nd_pfn->uuid, pfn_sb->uuid, 16) != 0)
                        return -ENODEV;

                /*
                 * If the uuid validates, but other settings mismatch
                 * return EINVAL because userspace has managed to change
                 * the configuration without specifying new
                 * identification.
                 */
                if (nd_pfn->align != align || nd_pfn->mode != mode) {
                        dev_err(&nd_pfn->dev,
                                        "init failed, settings mismatch\n");
                        dev_dbg(&nd_pfn->dev, "align: %lx:%lx mode: %d:%d\n",
                                        nd_pfn->align, align, nd_pfn->mode,
                                        mode);
                        return -EINVAL;
                }
        }

        if (align > nvdimm_namespace_capacity(ndns)) {
                dev_err(&nd_pfn->dev, "alignment: %lx exceeds capacity %llx\n",
                                align, nvdimm_namespace_capacity(ndns));
                return -EINVAL;
        }

        /*
         * These warnings are verbose because they can only trigger in
         * the case where the physical address alignment of the
         * namespace has changed since the pfn superblock was
         * established.
         */
        nsio = to_nd_namespace_io(&ndns->dev);
        if (offset >= resource_size(&nsio->res)) {
                dev_err(&nd_pfn->dev, "pfn array size exceeds capacity of %s\n",
                                dev_name(&ndns->dev));
                return -EBUSY;
        }

        if ((align && !IS_ALIGNED(nsio->res.start + offset + start_pad, align))
                        || !IS_ALIGNED(offset, PAGE_SIZE)) {
                dev_err(&nd_pfn->dev,
                                "bad offset: %#llx dax disabled align: %#lx\n",
                                offset, align);
                return -ENXIO;
        }

        return 0;
}
EXPORT_SYMBOL(nd_pfn_validate);

int nd_pfn_probe(struct device *dev, struct nd_namespace_common *ndns)
{
        int rc;
        struct nd_pfn *nd_pfn;
        struct device *pfn_dev;
        struct nd_pfn_sb *pfn_sb;
        struct nd_region *nd_region = to_nd_region(ndns->dev.parent);

        if (ndns->force_raw)
                return -ENODEV;

        switch (ndns->claim_class) {
        case NVDIMM_CCLASS_NONE:
        case NVDIMM_CCLASS_PFN:
                break;
        default:
                return -ENODEV;
        }

        nvdimm_bus_lock(&ndns->dev);
        nd_pfn = nd_pfn_alloc(nd_region);
        pfn_dev = nd_pfn_devinit(nd_pfn, ndns);
        nvdimm_bus_unlock(&ndns->dev);
        if (!pfn_dev)
                return -ENOMEM;
        pfn_sb = devm_kmalloc(dev, sizeof(*pfn_sb), GFP_KERNEL);
        nd_pfn = to_nd_pfn(pfn_dev);
        nd_pfn->pfn_sb = pfn_sb;
        rc = nd_pfn_validate(nd_pfn, PFN_SIG);
        dev_dbg(dev, "pfn: %s\n", rc == 0 ? dev_name(pfn_dev) : "<none>");
        if (rc < 0) {
                nd_detach_ndns(pfn_dev, &nd_pfn->ndns);
                put_device(pfn_dev);
        } else
                __nd_device_register(pfn_dev);

        return rc;
}
EXPORT_SYMBOL(nd_pfn_probe);

/*
 * We hotplug memory at sub-section granularity, pad the reserved area
 * from the previous section base to the namespace base address.
 */
static unsigned long init_altmap_base(resource_size_t base)
{
        unsigned long base_pfn = PHYS_PFN(base);

        return SUBSECTION_ALIGN_DOWN(base_pfn);
}

static unsigned long init_altmap_reserve(resource_size_t base)
{
        unsigned long reserve = nd_info_block_reserve() >> PAGE_SHIFT;
        unsigned long base_pfn = PHYS_PFN(base);

        reserve += base_pfn - SUBSECTION_ALIGN_DOWN(base_pfn);
        return reserve;
}

static int __nvdimm_setup_pfn(struct nd_pfn *nd_pfn, struct dev_pagemap *pgmap)
{
        struct resource *res = &pgmap->res;
        struct vmem_altmap *altmap = &pgmap->altmap;
        struct nd_pfn_sb *pfn_sb = nd_pfn->pfn_sb;
        u64 offset = le64_to_cpu(pfn_sb->dataoff);
        u32 start_pad = __le32_to_cpu(pfn_sb->start_pad);
        u32 end_trunc = __le32_to_cpu(pfn_sb->end_trunc);
        u32 reserve = nd_info_block_reserve();
        struct nd_namespace_common *ndns = nd_pfn->ndns;
        struct nd_namespace_io *nsio = to_nd_namespace_io(&ndns->dev);
        resource_size_t base = nsio->res.start + start_pad;
        resource_size_t end = nsio->res.end - end_trunc;
        struct vmem_altmap __altmap = {
                .base_pfn = init_altmap_base(base),
                .reserve = init_altmap_reserve(base),
                .end_pfn = PHYS_PFN(end),
        };

        memcpy(res, &nsio->res, sizeof(*res));
        res->start += start_pad;
        res->end -= end_trunc;

        if (nd_pfn->mode == PFN_MODE_RAM) {
                if (offset < reserve)
                        return -EINVAL;
                nd_pfn->npfns = le64_to_cpu(pfn_sb->npfns);
        } else if (nd_pfn->mode == PFN_MODE_PMEM) {
                nd_pfn->npfns = PHYS_PFN((resource_size(res) - offset));
                if (le64_to_cpu(nd_pfn->pfn_sb->npfns) > nd_pfn->npfns)
                        dev_info(&nd_pfn->dev,
                                        "number of pfns truncated from %lld to %ld\n",
                                        le64_to_cpu(nd_pfn->pfn_sb->npfns),
                                        nd_pfn->npfns);
                memcpy(altmap, &__altmap, sizeof(*altmap));
                altmap->free = PHYS_PFN(offset - reserve);
                altmap->alloc = 0;
                pgmap->flags |= PGMAP_ALTMAP_VALID;
        } else
                return -ENXIO;

        return 0;
}

static int nd_pfn_init(struct nd_pfn *nd_pfn)
{
        struct nd_namespace_common *ndns = nd_pfn->ndns;
        struct nd_namespace_io *nsio = to_nd_namespace_io(&ndns->dev);
        resource_size_t start, size;
        struct nd_region *nd_region;
        unsigned long npfns, align;
        u32 end_trunc;
        struct nd_pfn_sb *pfn_sb;
        phys_addr_t offset;
        const char *sig;
        u64 checksum;
        int rc;

        pfn_sb = devm_kmalloc(&nd_pfn->dev, sizeof(*pfn_sb), GFP_KERNEL);
        if (!pfn_sb)
                return -ENOMEM;

        nd_pfn->pfn_sb = pfn_sb;
        if (is_nd_dax(&nd_pfn->dev))
                sig = DAX_SIG;
        else
                sig = PFN_SIG;

        rc = nd_pfn_validate(nd_pfn, sig);
        if (rc == 0)
                return nd_pfn_clear_memmap_errors(nd_pfn);
        if (rc != -ENODEV)
                return rc;

        /* no info block, do init */;
        memset(pfn_sb, 0, sizeof(*pfn_sb));

        nd_region = to_nd_region(nd_pfn->dev.parent);
        if (nd_region->ro) {
                dev_info(&nd_pfn->dev,
                                "%s is read-only, unable to init metadata\n",
                                dev_name(&nd_region->dev));
                return -ENXIO;
        }

        /*
         * Note, we use 64 here for the standard size of struct page,
         * debugging options may cause it to be larger in which case the
         * implementation will limit the pfns advertised through
         * ->direct_access() to those that are included in the memmap.
         */
        start = nsio->res.start;
        size = resource_size(&nsio->res);
        npfns = PHYS_PFN(size - SZ_8K);
        align = max(nd_pfn->align, (1UL << SUBSECTION_SHIFT));
        end_trunc = start + size - ALIGN_DOWN(start + size, align);
        if (nd_pfn->mode == PFN_MODE_PMEM) {
                /*
                 * The altmap should be padded out to the block size used
                 * when populating the vmemmap. This *should* be equal to
                 * PMD_SIZE for most architectures.
                 *
                 * Also make sure size of struct page is less than 64. We
                 * want to make sure we use large enough size here so that
                 * we don't have a dynamic reserve space depending on
                 * struct page size. But we also want to make sure we notice
                 * when we end up adding new elements to struct page.
                 */
                BUILD_BUG_ON(sizeof(struct page) > MAX_STRUCT_PAGE_SIZE);
                offset = ALIGN(start + SZ_8K + MAX_STRUCT_PAGE_SIZE * npfns, align)
                        - start;
        } else if (nd_pfn->mode == PFN_MODE_RAM)
                offset = ALIGN(start + SZ_8K, align) - start;
        else
                return -ENXIO;

        if (offset >= size) {
                dev_err(&nd_pfn->dev, "%s unable to satisfy requested alignment\n",
                                dev_name(&ndns->dev));
                return -ENXIO;
        }

        npfns = PHYS_PFN(size - offset - end_trunc);
        pfn_sb->mode = cpu_to_le32(nd_pfn->mode);
        pfn_sb->dataoff = cpu_to_le64(offset);
        pfn_sb->npfns = cpu_to_le64(npfns);
        memcpy(pfn_sb->signature, sig, PFN_SIG_LEN);
        memcpy(pfn_sb->uuid, nd_pfn->uuid, 16);
        memcpy(pfn_sb->parent_uuid, nd_dev_to_uuid(&ndns->dev), 16);
        pfn_sb->version_major = cpu_to_le16(1);
        pfn_sb->version_minor = cpu_to_le16(4);
        pfn_sb->end_trunc = cpu_to_le32(end_trunc);
        pfn_sb->align = cpu_to_le32(nd_pfn->align);
        pfn_sb->page_struct_size = cpu_to_le16(MAX_STRUCT_PAGE_SIZE);
        pfn_sb->page_size = cpu_to_le32(PAGE_SIZE);
        checksum = nd_sb_checksum((struct nd_gen_sb *) pfn_sb);
        pfn_sb->checksum = cpu_to_le64(checksum);

        rc = nd_pfn_clear_memmap_errors(nd_pfn);
        if (rc)
                return rc;

        return nvdimm_write_bytes(ndns, SZ_4K, pfn_sb, sizeof(*pfn_sb), 0);
}

/*
 * Determine the effective resource range and vmem_altmap from an nd_pfn
 * instance.
 */
int nvdimm_setup_pfn(struct nd_pfn *nd_pfn, struct dev_pagemap *pgmap)
{
        int rc;

        if (!nd_pfn->uuid || !nd_pfn->ndns)
                return -ENODEV;

        rc = nd_pfn_init(nd_pfn);
        if (rc)
                return rc;

        /* we need a valid pfn_sb before we can init a dev_pagemap */
        return __nvdimm_setup_pfn(nd_pfn, pgmap);
}
EXPORT_SYMBOL_GPL(nvdimm_setup_pfn);