Merge tag 'trace-printf-v6.13' of git://git.kernel.org/pub/scm/linux/kernel/git/trace...

[drm/drm-misc.git] / drivers / nvdimm / pmem.c

// SPDX-License-Identifier: GPL-2.0-only
/*
 * Persistent Memory Driver
 *
 * Copyright (c) 2014-2015, Intel Corporation.
 * Copyright (c) 2015, Christoph Hellwig <hch@lst.de>.
 * Copyright (c) 2015, Boaz Harrosh <boaz@plexistor.com>.
 */

#include <linux/blkdev.h>
#include <linux/pagemap.h>
#include <linux/hdreg.h>
#include <linux/init.h>
#include <linux/platform_device.h>
#include <linux/set_memory.h>
#include <linux/module.h>
#include <linux/moduleparam.h>
#include <linux/badblocks.h>
#include <linux/memremap.h>
#include <linux/kstrtox.h>
#include <linux/vmalloc.h>
#include <linux/blk-mq.h>
#include <linux/pfn_t.h>
#include <linux/slab.h>
#include <linux/uio.h>
#include <linux/dax.h>
#include <linux/nd.h>
#include <linux/mm.h>
#include <asm/cacheflush.h>
#include "pmem.h"
#include "btt.h"
#include "pfn.h"
#include "nd.h"

static struct device *to_dev(struct pmem_device *pmem)
{
        /*
         * nvdimm bus services need a 'dev' parameter, and we record the device
         * at init in bb.dev.
         */
        return pmem->bb.dev;
}

static struct nd_region *to_region(struct pmem_device *pmem)
{
        return to_nd_region(to_dev(pmem)->parent);
}

static phys_addr_t pmem_to_phys(struct pmem_device *pmem, phys_addr_t offset)
{
        return pmem->phys_addr + offset;
}

static sector_t to_sect(struct pmem_device *pmem, phys_addr_t offset)
{
        return (offset - pmem->data_offset) >> SECTOR_SHIFT;
}

static phys_addr_t to_offset(struct pmem_device *pmem, sector_t sector)
{
        return (sector << SECTOR_SHIFT) + pmem->data_offset;
}

static void pmem_mkpage_present(struct pmem_device *pmem, phys_addr_t offset,
                unsigned int len)
{
        phys_addr_t phys = pmem_to_phys(pmem, offset);
        unsigned long pfn_start, pfn_end, pfn;

        /* only pmem in the linear map supports HWPoison */
        if (is_vmalloc_addr(pmem->virt_addr))
                return;

        pfn_start = PHYS_PFN(phys);
        pfn_end = pfn_start + PHYS_PFN(len);
        for (pfn = pfn_start; pfn < pfn_end; pfn++) {
                struct page *page = pfn_to_page(pfn);

                /*
                 * Note, no need to hold a get_dev_pagemap() reference
                 * here since we're in the driver I/O path and
                 * outstanding I/O requests pin the dev_pagemap.
                 */
                if (test_and_clear_pmem_poison(page))
                        clear_mce_nospec(pfn);
        }
}

static void pmem_clear_bb(struct pmem_device *pmem, sector_t sector, long blks)
{
        if (blks == 0)
                return;
        badblocks_clear(&pmem->bb, sector, blks);
        if (pmem->bb_state)
                sysfs_notify_dirent(pmem->bb_state);
}

static long __pmem_clear_poison(struct pmem_device *pmem,
                phys_addr_t offset, unsigned int len)
{
        phys_addr_t phys = pmem_to_phys(pmem, offset);
        long cleared = nvdimm_clear_poison(to_dev(pmem), phys, len);

        if (cleared > 0) {
                pmem_mkpage_present(pmem, offset, cleared);
                arch_invalidate_pmem(pmem->virt_addr + offset, len);
        }
        return cleared;
}

static blk_status_t pmem_clear_poison(struct pmem_device *pmem,
                phys_addr_t offset, unsigned int len)
{
        long cleared = __pmem_clear_poison(pmem, offset, len);

        if (cleared < 0)
                return BLK_STS_IOERR;

        pmem_clear_bb(pmem, to_sect(pmem, offset), cleared >> SECTOR_SHIFT);
        if (cleared < len)
                return BLK_STS_IOERR;
        return BLK_STS_OK;
}

static void write_pmem(void *pmem_addr, struct page *page,
                unsigned int off, unsigned int len)
{
        unsigned int chunk;
        void *mem;

        while (len) {
                mem = kmap_atomic(page);
                chunk = min_t(unsigned int, len, PAGE_SIZE - off);
                memcpy_flushcache(pmem_addr, mem + off, chunk);
                kunmap_atomic(mem);
                len -= chunk;
                off = 0;
                page++;
                pmem_addr += chunk;
        }
}

static blk_status_t read_pmem(struct page *page, unsigned int off,
                void *pmem_addr, unsigned int len)
{
        unsigned int chunk;
        unsigned long rem;
        void *mem;

        while (len) {
                mem = kmap_atomic(page);
                chunk = min_t(unsigned int, len, PAGE_SIZE - off);
                rem = copy_mc_to_kernel(mem + off, pmem_addr, chunk);
                kunmap_atomic(mem);
                if (rem)
                        return BLK_STS_IOERR;
                len -= chunk;
                off = 0;
                page++;
                pmem_addr += chunk;
        }
        return BLK_STS_OK;
}

static blk_status_t pmem_do_read(struct pmem_device *pmem,
                        struct page *page, unsigned int page_off,
                        sector_t sector, unsigned int len)
{
        blk_status_t rc;
        phys_addr_t pmem_off = to_offset(pmem, sector);
        void *pmem_addr = pmem->virt_addr + pmem_off;

        if (unlikely(is_bad_pmem(&pmem->bb, sector, len)))
                return BLK_STS_IOERR;

        rc = read_pmem(page, page_off, pmem_addr, len);
        flush_dcache_page(page);
        return rc;
}

static blk_status_t pmem_do_write(struct pmem_device *pmem,
                        struct page *page, unsigned int page_off,
                        sector_t sector, unsigned int len)
{
        phys_addr_t pmem_off = to_offset(pmem, sector);
        void *pmem_addr = pmem->virt_addr + pmem_off;

        if (unlikely(is_bad_pmem(&pmem->bb, sector, len))) {
                blk_status_t rc = pmem_clear_poison(pmem, pmem_off, len);

                if (rc != BLK_STS_OK)
                        return rc;
        }

        flush_dcache_page(page);
        write_pmem(pmem_addr, page, page_off, len);

        return BLK_STS_OK;
}

static void pmem_submit_bio(struct bio *bio)
{
        int ret = 0;
        blk_status_t rc = 0;
        bool do_acct;
        unsigned long start;
        struct bio_vec bvec;
        struct bvec_iter iter;
        struct pmem_device *pmem = bio->bi_bdev->bd_disk->private_data;
        struct nd_region *nd_region = to_region(pmem);

        if (bio->bi_opf & REQ_PREFLUSH)
                ret = nvdimm_flush(nd_region, bio);

        do_acct = blk_queue_io_stat(bio->bi_bdev->bd_disk->queue);
        if (do_acct)
                start = bio_start_io_acct(bio);
        bio_for_each_segment(bvec, bio, iter) {
                if (op_is_write(bio_op(bio)))
                        rc = pmem_do_write(pmem, bvec.bv_page, bvec.bv_offset,
                                iter.bi_sector, bvec.bv_len);
                else
                        rc = pmem_do_read(pmem, bvec.bv_page, bvec.bv_offset,
                                iter.bi_sector, bvec.bv_len);
                if (rc) {
                        bio->bi_status = rc;
                        break;
                }
        }
        if (do_acct)
                bio_end_io_acct(bio, start);

        if (bio->bi_opf & REQ_FUA)
                ret = nvdimm_flush(nd_region, bio);

        if (ret)
                bio->bi_status = errno_to_blk_status(ret);

        bio_endio(bio);
}

/* see "strong" declaration in tools/testing/nvdimm/pmem-dax.c */
__weak long __pmem_direct_access(struct pmem_device *pmem, pgoff_t pgoff,
                long nr_pages, enum dax_access_mode mode, void **kaddr,
                pfn_t *pfn)
{
        resource_size_t offset = PFN_PHYS(pgoff) + pmem->data_offset;
        sector_t sector = PFN_PHYS(pgoff) >> SECTOR_SHIFT;
        unsigned int num = PFN_PHYS(nr_pages) >> SECTOR_SHIFT;
        struct badblocks *bb = &pmem->bb;
        sector_t first_bad;
        int num_bad;

        if (kaddr)
                *kaddr = pmem->virt_addr + offset;
        if (pfn)
                *pfn = phys_to_pfn_t(pmem->phys_addr + offset, pmem->pfn_flags);

        if (bb->count &&
            badblocks_check(bb, sector, num, &first_bad, &num_bad)) {
                long actual_nr;

                if (mode != DAX_RECOVERY_WRITE)
                        return -EHWPOISON;

                /*
                 * Set the recovery stride is set to kernel page size because
                 * the underlying driver and firmware clear poison functions
                 * don't appear to handle large chunk(such as 2MiB) reliably.
                 */
                actual_nr = PHYS_PFN(
                        PAGE_ALIGN((first_bad - sector) << SECTOR_SHIFT));
                dev_dbg(pmem->bb.dev, "start sector(%llu), nr_pages(%ld), first_bad(%llu), actual_nr(%ld)\n",
                                sector, nr_pages, first_bad, actual_nr);
                if (actual_nr)
                        return actual_nr;
                return 1;
        }

        /*
         * If badblocks are present but not in the range, limit known good range
         * to the requested range.
         */
        if (bb->count)
                return nr_pages;
        return PHYS_PFN(pmem->size - pmem->pfn_pad - offset);
}

static const struct block_device_operations pmem_fops = {
        .owner =                THIS_MODULE,
        .submit_bio =           pmem_submit_bio,
};

static int pmem_dax_zero_page_range(struct dax_device *dax_dev, pgoff_t pgoff,
                                    size_t nr_pages)
{
        struct pmem_device *pmem = dax_get_private(dax_dev);

        return blk_status_to_errno(pmem_do_write(pmem, ZERO_PAGE(0), 0,
                                   PFN_PHYS(pgoff) >> SECTOR_SHIFT,
                                   PAGE_SIZE));
}

static long pmem_dax_direct_access(struct dax_device *dax_dev,
                pgoff_t pgoff, long nr_pages, enum dax_access_mode mode,
                void **kaddr, pfn_t *pfn)
{
        struct pmem_device *pmem = dax_get_private(dax_dev);

        return __pmem_direct_access(pmem, pgoff, nr_pages, mode, kaddr, pfn);
}

/*
 * The recovery write thread started out as a normal pwrite thread and
 * when the filesystem was told about potential media error in the
 * range, filesystem turns the normal pwrite to a dax_recovery_write.
 *
 * The recovery write consists of clearing media poison, clearing page
 * HWPoison bit, re-enable page-wide read-write permission, flush the
 * caches and finally write.  A competing pread thread will be held
 * off during the recovery process since data read back might not be
 * valid, and this is achieved by clearing the badblock records after
 * the recovery write is complete. Competing recovery write threads
 * are already serialized by writer lock held by dax_iomap_rw().
 */
static size_t pmem_recovery_write(struct dax_device *dax_dev, pgoff_t pgoff,
                void *addr, size_t bytes, struct iov_iter *i)
{
        struct pmem_device *pmem = dax_get_private(dax_dev);
        size_t olen, len, off;
        phys_addr_t pmem_off;
        struct device *dev = pmem->bb.dev;
        long cleared;

        off = offset_in_page(addr);
        len = PFN_PHYS(PFN_UP(off + bytes));
        if (!is_bad_pmem(&pmem->bb, PFN_PHYS(pgoff) >> SECTOR_SHIFT, len))
                return _copy_from_iter_flushcache(addr, bytes, i);

        /*
         * Not page-aligned range cannot be recovered. This should not
         * happen unless something else went wrong.
         */
        if (off || !PAGE_ALIGNED(bytes)) {
                dev_dbg(dev, "Found poison, but addr(%p) or bytes(%#zx) not page aligned\n",
                        addr, bytes);
                return 0;
        }

        pmem_off = PFN_PHYS(pgoff) + pmem->data_offset;
        cleared = __pmem_clear_poison(pmem, pmem_off, len);
        if (cleared > 0 && cleared < len) {
                dev_dbg(dev, "poison cleared only %ld out of %zu bytes\n",
                        cleared, len);
                return 0;
        }
        if (cleared < 0) {
                dev_dbg(dev, "poison clear failed: %ld\n", cleared);
                return 0;
        }

        olen = _copy_from_iter_flushcache(addr, bytes, i);
        pmem_clear_bb(pmem, to_sect(pmem, pmem_off), cleared >> SECTOR_SHIFT);

        return olen;
}

static const struct dax_operations pmem_dax_ops = {
        .direct_access = pmem_dax_direct_access,
        .zero_page_range = pmem_dax_zero_page_range,
        .recovery_write = pmem_recovery_write,
};

static ssize_t write_cache_show(struct device *dev,
                struct device_attribute *attr, char *buf)
{
        struct pmem_device *pmem = dev_to_disk(dev)->private_data;

        return sprintf(buf, "%d\n", !!dax_write_cache_enabled(pmem->dax_dev));
}

static ssize_t write_cache_store(struct device *dev,
                struct device_attribute *attr, const char *buf, size_t len)
{
        struct pmem_device *pmem = dev_to_disk(dev)->private_data;
        bool write_cache;
        int rc;

        rc = kstrtobool(buf, &write_cache);
        if (rc)
                return rc;
        dax_write_cache(pmem->dax_dev, write_cache);
        return len;
}
static DEVICE_ATTR_RW(write_cache);

static umode_t dax_visible(struct kobject *kobj, struct attribute *a, int n)
{
#ifndef CONFIG_ARCH_HAS_PMEM_API
        if (a == &dev_attr_write_cache.attr)
                return 0;
#endif
        return a->mode;
}

static struct attribute *dax_attributes[] = {
        &dev_attr_write_cache.attr,
        NULL,
};

static const struct attribute_group dax_attribute_group = {
        .name           = "dax",
        .attrs          = dax_attributes,
        .is_visible     = dax_visible,
};

static const struct attribute_group *pmem_attribute_groups[] = {
        &dax_attribute_group,
        NULL,
};

static void pmem_release_disk(void *__pmem)
{
        struct pmem_device *pmem = __pmem;

        dax_remove_host(pmem->disk);
        kill_dax(pmem->dax_dev);
        put_dax(pmem->dax_dev);
        del_gendisk(pmem->disk);

        put_disk(pmem->disk);
}

static int pmem_pagemap_memory_failure(struct dev_pagemap *pgmap,
                unsigned long pfn, unsigned long nr_pages, int mf_flags)
{
        struct pmem_device *pmem =
                        container_of(pgmap, struct pmem_device, pgmap);
        u64 offset = PFN_PHYS(pfn) - pmem->phys_addr - pmem->data_offset;
        u64 len = nr_pages << PAGE_SHIFT;

        return dax_holder_notify_failure(pmem->dax_dev, offset, len, mf_flags);
}

static const struct dev_pagemap_ops fsdax_pagemap_ops = {
        .memory_failure         = pmem_pagemap_memory_failure,
};

static int pmem_attach_disk(struct device *dev,
                struct nd_namespace_common *ndns)
{
        struct nd_namespace_io *nsio = to_nd_namespace_io(&ndns->dev);
        struct nd_region *nd_region = to_nd_region(dev->parent);
        struct queue_limits lim = {
                .logical_block_size     = pmem_sector_size(ndns),
                .physical_block_size    = PAGE_SIZE,
                .max_hw_sectors         = UINT_MAX,
                .features               = BLK_FEAT_WRITE_CACHE |
                                          BLK_FEAT_SYNCHRONOUS,
        };
        int nid = dev_to_node(dev), fua;
        struct resource *res = &nsio->res;
        struct range bb_range;
        struct nd_pfn *nd_pfn = NULL;
        struct dax_device *dax_dev;
        struct nd_pfn_sb *pfn_sb;
        struct pmem_device *pmem;
        struct gendisk *disk;
        void *addr;
        int rc;

        pmem = devm_kzalloc(dev, sizeof(*pmem), GFP_KERNEL);
        if (!pmem)
                return -ENOMEM;

        rc = devm_namespace_enable(dev, ndns, nd_info_block_reserve());
        if (rc)
                return rc;

        /* while nsio_rw_bytes is active, parse a pfn info block if present */
        if (is_nd_pfn(dev)) {
                nd_pfn = to_nd_pfn(dev);
                rc = nvdimm_setup_pfn(nd_pfn, &pmem->pgmap);
                if (rc)
                        return rc;
        }

        /* we're attaching a block device, disable raw namespace access */
        devm_namespace_disable(dev, ndns);

        dev_set_drvdata(dev, pmem);
        pmem->phys_addr = res->start;
        pmem->size = resource_size(res);
        fua = nvdimm_has_flush(nd_region);
        if (!IS_ENABLED(CONFIG_ARCH_HAS_UACCESS_FLUSHCACHE) || fua < 0) {
                dev_warn(dev, "unable to guarantee persistence of writes\n");
                fua = 0;
        }
        if (fua)
                lim.features |= BLK_FEAT_FUA;
        if (is_nd_pfn(dev) || pmem_should_map_pages(dev))
                lim.features |= BLK_FEAT_DAX;

        if (!devm_request_mem_region(dev, res->start, resource_size(res),
                                dev_name(&ndns->dev))) {
                dev_warn(dev, "could not reserve region %pR\n", res);
                return -EBUSY;
        }

        disk = blk_alloc_disk(&lim, nid);
        if (IS_ERR(disk))
                return PTR_ERR(disk);

        pmem->disk = disk;
        pmem->pgmap.owner = pmem;
        pmem->pfn_flags = PFN_DEV;
        if (is_nd_pfn(dev)) {
                pmem->pgmap.type = MEMORY_DEVICE_FS_DAX;
                pmem->pgmap.ops = &fsdax_pagemap_ops;
                addr = devm_memremap_pages(dev, &pmem->pgmap);
                pfn_sb = nd_pfn->pfn_sb;
                pmem->data_offset = le64_to_cpu(pfn_sb->dataoff);
                pmem->pfn_pad = resource_size(res) -
                        range_len(&pmem->pgmap.range);
                pmem->pfn_flags |= PFN_MAP;
                bb_range = pmem->pgmap.range;
                bb_range.start += pmem->data_offset;
        } else if (pmem_should_map_pages(dev)) {
                pmem->pgmap.range.start = res->start;
                pmem->pgmap.range.end = res->end;
                pmem->pgmap.nr_range = 1;
                pmem->pgmap.type = MEMORY_DEVICE_FS_DAX;
                pmem->pgmap.ops = &fsdax_pagemap_ops;
                addr = devm_memremap_pages(dev, &pmem->pgmap);
                pmem->pfn_flags |= PFN_MAP;
                bb_range = pmem->pgmap.range;
        } else {
                addr = devm_memremap(dev, pmem->phys_addr,
                                pmem->size, ARCH_MEMREMAP_PMEM);
                bb_range.start =  res->start;
                bb_range.end = res->end;
        }

        if (IS_ERR(addr)) {
                rc = PTR_ERR(addr);
                goto out;
        }
        pmem->virt_addr = addr;

        disk->fops              = &pmem_fops;
        disk->private_data      = pmem;
        nvdimm_namespace_disk_name(ndns, disk->disk_name);
        set_capacity(disk, (pmem->size - pmem->pfn_pad - pmem->data_offset)
                        / 512);
        if (devm_init_badblocks(dev, &pmem->bb))
                return -ENOMEM;
        nvdimm_badblocks_populate(nd_region, &pmem->bb, &bb_range);
        disk->bb = &pmem->bb;

        dax_dev = alloc_dax(pmem, &pmem_dax_ops);
        if (IS_ERR(dax_dev)) {
                rc = PTR_ERR(dax_dev);
                if (rc != -EOPNOTSUPP)
                        goto out;
        } else {
                set_dax_nocache(dax_dev);
                set_dax_nomc(dax_dev);
                if (is_nvdimm_sync(nd_region))
                        set_dax_synchronous(dax_dev);
                pmem->dax_dev = dax_dev;
                rc = dax_add_host(dax_dev, disk);
                if (rc)
                        goto out_cleanup_dax;
                dax_write_cache(dax_dev, nvdimm_has_cache(nd_region));
        }
        rc = device_add_disk(dev, disk, pmem_attribute_groups);
        if (rc)
                goto out_remove_host;
        if (devm_add_action_or_reset(dev, pmem_release_disk, pmem))
                return -ENOMEM;

        nvdimm_check_and_set_ro(disk);

        pmem->bb_state = sysfs_get_dirent(disk_to_dev(disk)->kobj.sd,
                                          "badblocks");
        if (!pmem->bb_state)
                dev_warn(dev, "'badblocks' notification disabled\n");
        return 0;

out_remove_host:
        dax_remove_host(pmem->disk);
out_cleanup_dax:
        kill_dax(pmem->dax_dev);
        put_dax(pmem->dax_dev);
out:
        put_disk(pmem->disk);
        return rc;
}

static int nd_pmem_probe(struct device *dev)
{
        int ret;
        struct nd_namespace_common *ndns;

        ndns = nvdimm_namespace_common_probe(dev);
        if (IS_ERR(ndns))
                return PTR_ERR(ndns);

        if (is_nd_btt(dev))
                return nvdimm_namespace_attach_btt(ndns);

        if (is_nd_pfn(dev))
                return pmem_attach_disk(dev, ndns);

        ret = devm_namespace_enable(dev, ndns, nd_info_block_reserve());
        if (ret)
                return ret;

        ret = nd_btt_probe(dev, ndns);
        if (ret == 0)
                return -ENXIO;

        /*
         * We have two failure conditions here, there is no
         * info reserver block or we found a valid info reserve block
         * but failed to initialize the pfn superblock.
         *
         * For the first case consider namespace as a raw pmem namespace
         * and attach a disk.
         *
         * For the latter, consider this a success and advance the namespace
         * seed.
         */
        ret = nd_pfn_probe(dev, ndns);
        if (ret == 0)
                return -ENXIO;
        else if (ret == -EOPNOTSUPP)
                return ret;

        ret = nd_dax_probe(dev, ndns);
        if (ret == 0)
                return -ENXIO;
        else if (ret == -EOPNOTSUPP)
                return ret;

        /* probe complete, attach handles namespace enabling */
        devm_namespace_disable(dev, ndns);

        return pmem_attach_disk(dev, ndns);
}

static void nd_pmem_remove(struct device *dev)
{
        struct pmem_device *pmem = dev_get_drvdata(dev);

        if (is_nd_btt(dev))
                nvdimm_namespace_detach_btt(to_nd_btt(dev));
        else {
                /*
                 * Note, this assumes device_lock() context to not
                 * race nd_pmem_notify()
                 */
                sysfs_put(pmem->bb_state);
                pmem->bb_state = NULL;
        }
        nvdimm_flush(to_nd_region(dev->parent), NULL);
}

static void nd_pmem_shutdown(struct device *dev)
{
        nvdimm_flush(to_nd_region(dev->parent), NULL);
}

static void pmem_revalidate_poison(struct device *dev)
{
        struct nd_region *nd_region;
        resource_size_t offset = 0, end_trunc = 0;
        struct nd_namespace_common *ndns;
        struct nd_namespace_io *nsio;
        struct badblocks *bb;
        struct range range;
        struct kernfs_node *bb_state;

        if (is_nd_btt(dev)) {
                struct nd_btt *nd_btt = to_nd_btt(dev);

                ndns = nd_btt->ndns;
                nd_region = to_nd_region(ndns->dev.parent);
                nsio = to_nd_namespace_io(&ndns->dev);
                bb = &nsio->bb;
                bb_state = NULL;
        } else {
                struct pmem_device *pmem = dev_get_drvdata(dev);

                nd_region = to_region(pmem);
                bb = &pmem->bb;
                bb_state = pmem->bb_state;

                if (is_nd_pfn(dev)) {
                        struct nd_pfn *nd_pfn = to_nd_pfn(dev);
                        struct nd_pfn_sb *pfn_sb = nd_pfn->pfn_sb;

                        ndns = nd_pfn->ndns;
                        offset = pmem->data_offset +
                                        __le32_to_cpu(pfn_sb->start_pad);
                        end_trunc = __le32_to_cpu(pfn_sb->end_trunc);
                } else {
                        ndns = to_ndns(dev);
                }

                nsio = to_nd_namespace_io(&ndns->dev);
        }

        range.start = nsio->res.start + offset;
        range.end = nsio->res.end - end_trunc;
        nvdimm_badblocks_populate(nd_region, bb, &range);
        if (bb_state)
                sysfs_notify_dirent(bb_state);
}

static void pmem_revalidate_region(struct device *dev)
{
        struct pmem_device *pmem;

        if (is_nd_btt(dev)) {
                struct nd_btt *nd_btt = to_nd_btt(dev);
                struct btt *btt = nd_btt->btt;

                nvdimm_check_and_set_ro(btt->btt_disk);
                return;
        }

        pmem = dev_get_drvdata(dev);
        nvdimm_check_and_set_ro(pmem->disk);
}

static void nd_pmem_notify(struct device *dev, enum nvdimm_event event)
{
        switch (event) {
        case NVDIMM_REVALIDATE_POISON:
                pmem_revalidate_poison(dev);
                break;
        case NVDIMM_REVALIDATE_REGION:
                pmem_revalidate_region(dev);
                break;
        default:
                dev_WARN_ONCE(dev, 1, "notify: unknown event: %d\n", event);
                break;
        }
}

MODULE_ALIAS("pmem");
MODULE_ALIAS_ND_DEVICE(ND_DEVICE_NAMESPACE_IO);
MODULE_ALIAS_ND_DEVICE(ND_DEVICE_NAMESPACE_PMEM);
static struct nd_device_driver nd_pmem_driver = {
        .probe = nd_pmem_probe,
        .remove = nd_pmem_remove,
        .notify = nd_pmem_notify,
        .shutdown = nd_pmem_shutdown,
        .drv = {
                .name = "nd_pmem",
        },
        .type = ND_DRIVER_NAMESPACE_IO | ND_DRIVER_NAMESPACE_PMEM,
};

module_nd_driver(nd_pmem_driver);

MODULE_AUTHOR("Ross Zwisler <ross.zwisler@linux.intel.com>");
MODULE_DESCRIPTION("NVDIMM Persistent Memory Driver");
MODULE_LICENSE("GPL v2");