libnvdimm, pfn: 'struct page' provider infrastructure

Implement the base infrastructure for libnvdimm PFN devices. Similar to
BTT devices they take a namespace as a backing device and layer
functionality on top. In this case the functionality is reserving space
for an array of 'struct page' entries to be handed out through
pfn_to_page(). For now this is just the basic libnvdimm-device-model for
configuring the base PFN device.

As the namespace claiming mechanism for PFN devices is mostly identical
to BTT devices drivers/nvdimm/claim.c is created to house the common
bits.

Cc: Ross Zwisler <ross.zwisler@linux.intel.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>

13 files changed, 719 insertions, 177 deletions

diff --git a/drivers/nvdimm/Kconfig b/drivers/nvdimm/Kconfig
index 72226acb5c0f..ace25b53b755 100644
--- a/drivers/nvdimm/Kconfig
+++ b/drivers/nvdimm/Kconfig
@@ -21,6 +21,7 @@ config BLK_DEV_PMEM
         default LIBNVDIMM
         depends on HAS_IOMEM
         select ND_BTT if BTT
+        select ND_PFN if NVDIMM_PFN
         help
           Memory ranges for PMEM are described by either an NFIT
           (NVDIMM Firmware Interface Table, see CONFIG_NFIT_ACPI), a
@@ -47,12 +48,16 @@ config ND_BLK
           (CONFIG_ACPI_NFIT), or otherwise exposes BLK-mode
           capabilities.
 
+config ND_CLAIM
+        bool
+
 config ND_BTT
         tristate
 
 config BTT
         bool "BTT: Block Translation Table (atomic sector updates)"
         default y if LIBNVDIMM
+        select ND_CLAIM
         help
           The Block Translation Table (BTT) provides atomic sector
           update semantics for persistent memory devices, so that
@@ -65,4 +70,21 @@ config BTT
 
           Select Y if unsure
 
+config ND_PFN
+        tristate
+
+config NVDIMM_PFN
+        bool "PFN: Map persistent (device) memory"
+        default LIBNVDIMM
+        select ND_CLAIM
+        help
+          Map persistent memory, i.e. advertise it to the memory
+          management sub-system.  By default persistent memory does
+          not support direct I/O, RDMA, or any other usage that
+          requires a 'struct page' to mediate an I/O request.  This
+          driver allocates and initializes the infrastructure needed
+          to support those use cases.
+
+          Select Y if unsure
+
 endif
diff --git a/drivers/nvdimm/Makefile b/drivers/nvdimm/Makefile
index 9bf15db52dee..ea84d3c4e8e5 100644
--- a/drivers/nvdimm/Makefile
+++ b/drivers/nvdimm/Makefile
@@ -20,4 +20,6 @@ libnvdimm-y += region_devs.o
 libnvdimm-y += region.o
 libnvdimm-y += namespace_devs.o
 libnvdimm-y += label.o
+libnvdimm-$(CONFIG_ND_CLAIM) += claim.o
 libnvdimm-$(CONFIG_BTT) += btt_devs.o
+libnvdimm-$(CONFIG_NVDIMM_PFN) += pfn_devs.o
diff --git a/drivers/nvdimm/btt.c b/drivers/nvdimm/btt.c
index 19588291550b..028d2d137bc5 100644
--- a/drivers/nvdimm/btt.c
+++ b/drivers/nvdimm/btt.c
@@ -731,6 +731,7 @@ static int create_arenas(struct btt *btt)
 static int btt_arena_write_layout(struct arena_info *arena)
 {
         int ret;
+        u64 sum;
         struct btt_sb *super;
         struct nd_btt *nd_btt = arena->nd_btt;
         const u8 *parent_uuid = nd_dev_to_uuid(&nd_btt->ndns->dev);
@@ -770,7 +771,8 @@ static int btt_arena_write_layout(struct arena_info *arena)
         super->info2off = cpu_to_le64(arena->info2off - arena->infooff);
 
         super->flags = 0;
-        super->checksum = cpu_to_le64(nd_btt_sb_checksum(super));
+        sum = nd_sb_checksum((struct nd_gen_sb *) super);
+        super->checksum = cpu_to_le64(sum);
 
         ret = btt_info_write(arena, super);
 
@@ -1422,8 +1424,6 @@ static int __init nd_btt_init(void)
 {
         int rc;
 
-        BUILD_BUG_ON(sizeof(struct btt_sb) != SZ_4K);
-
         btt_major = register_blkdev(0, "btt");
         if (btt_major < 0)
                 return btt_major;
diff --git a/drivers/nvdimm/btt_devs.c b/drivers/nvdimm/btt_devs.c
index 242ae1c550ad..59ad54a63d9f 100644
--- a/drivers/nvdimm/btt_devs.c
+++ b/drivers/nvdimm/btt_devs.c
@@ -21,63 +21,13 @@
 #include "btt.h"
 #include "nd.h"
 
-static void __nd_btt_detach_ndns(struct nd_btt *nd_btt)
-{
-        struct nd_namespace_common *ndns = nd_btt->ndns;
-
-        dev_WARN_ONCE(&nd_btt->dev, !mutex_is_locked(&ndns->dev.mutex)
-                        || ndns->claim != &nd_btt->dev,
-                        "%s: invalid claim\n", __func__);
-        ndns->claim = NULL;
-        nd_btt->ndns = NULL;
-        put_device(&ndns->dev);
-}
-
-static void nd_btt_detach_ndns(struct nd_btt *nd_btt)
-{
-        struct nd_namespace_common *ndns = nd_btt->ndns;
-
-        if (!ndns)
-                return;
-        get_device(&ndns->dev);
-        device_lock(&ndns->dev);
-        __nd_btt_detach_ndns(nd_btt);
-        device_unlock(&ndns->dev);
-        put_device(&ndns->dev);
-}
-
-static bool __nd_btt_attach_ndns(struct nd_btt *nd_btt,
-                struct nd_namespace_common *ndns)
-{
-        if (ndns->claim)
-                return false;
-        dev_WARN_ONCE(&nd_btt->dev, !mutex_is_locked(&ndns->dev.mutex)
-                        || nd_btt->ndns,
-                        "%s: invalid claim\n", __func__);
-        ndns->claim = &nd_btt->dev;
-        nd_btt->ndns = ndns;
-        get_device(&ndns->dev);
-        return true;
-}
-
-static bool nd_btt_attach_ndns(struct nd_btt *nd_btt,
-                struct nd_namespace_common *ndns)
-{
-        bool claimed;
-
-        device_lock(&ndns->dev);
-        claimed = __nd_btt_attach_ndns(nd_btt, ndns);
-        device_unlock(&ndns->dev);
-        return claimed;
-}
-
 static void nd_btt_release(struct device *dev)
 {
         struct nd_region *nd_region = to_nd_region(dev->parent);
         struct nd_btt *nd_btt = to_nd_btt(dev);
 
         dev_dbg(dev, "%s\n", __func__);
-        nd_btt_detach_ndns(nd_btt);
+        nd_detach_ndns(&nd_btt->dev, &nd_btt->ndns);
         ida_simple_remove(&nd_region->btt_ida, nd_btt->id);
         kfree(nd_btt->uuid);
         kfree(nd_btt);
@@ -172,104 +122,15 @@ static ssize_t namespace_show(struct device *dev,
         return rc;
 }
 
-static int namespace_match(struct device *dev, void *data)
-{
-        char *name = data;
-
-        return strcmp(name, dev_name(dev)) == 0;
-}
-
-static bool is_nd_btt_idle(struct device *dev)
-{
-        struct nd_region *nd_region = to_nd_region(dev->parent);
-        struct nd_btt *nd_btt = to_nd_btt(dev);
-
-        if (nd_region->btt_seed == dev || nd_btt->ndns || dev->driver)
-                return false;
-        return true;
-}
-
-static ssize_t __namespace_store(struct device *dev,
-                struct device_attribute *attr, const char *buf, size_t len)
-{
-        struct nd_btt *nd_btt = to_nd_btt(dev);
-        struct nd_namespace_common *ndns;
-        struct device *found;
-        char *name;
-
-        if (dev->driver) {
-                dev_dbg(dev, "%s: -EBUSY\n", __func__);
-                return -EBUSY;
-        }
-
-        name = kstrndup(buf, len, GFP_KERNEL);
-        if (!name)
-                return -ENOMEM;
-        strim(name);
-
-        if (strncmp(name, "namespace", 9) == 0 || strcmp(name, "") == 0)
-                /* pass */;
-        else {
-                len = -EINVAL;
-                goto out;
-        }
-
-        ndns = nd_btt->ndns;
-        if (strcmp(name, "") == 0) {
-                /* detach the namespace and destroy / reset the btt device */
-                nd_btt_detach_ndns(nd_btt);
-                if (is_nd_btt_idle(dev))
-                        nd_device_unregister(dev, ND_ASYNC);
-                else {
-                        nd_btt->lbasize = 0;
-                        kfree(nd_btt->uuid);
-                        nd_btt->uuid = NULL;
-                }
-                goto out;
-        } else if (ndns) {
-                dev_dbg(dev, "namespace already set to: %s\n",
-                                dev_name(&ndns->dev));
-                len = -EBUSY;
-                goto out;
-        }
-
-        found = device_find_child(dev->parent, name, namespace_match);
-        if (!found) {
-                dev_dbg(dev, "'%s' not found under %s\n", name,
-                                dev_name(dev->parent));
-                len = -ENODEV;
-                goto out;
-        }
-
-        ndns = to_ndns(found);
-        if (__nvdimm_namespace_capacity(ndns) < SZ_16M) {
-                dev_dbg(dev, "%s too small to host btt\n", name);
-                len = -ENXIO;
-                goto out_attach;
-        }
-
-        WARN_ON_ONCE(!is_nvdimm_bus_locked(&nd_btt->dev));
-        if (!nd_btt_attach_ndns(nd_btt, ndns)) {
-                dev_dbg(dev, "%s already claimed\n",
-                                dev_name(&ndns->dev));
-                len = -EBUSY;
-        }
-
- out_attach:
-        put_device(&ndns->dev); /* from device_find_child */
- out:
-        kfree(name);
-        return len;
-}
-
 static ssize_t namespace_store(struct device *dev,
                 struct device_attribute *attr, const char *buf, size_t len)
 {
+        struct nd_btt *nd_btt = to_nd_btt(dev);
         ssize_t rc;
 
         nvdimm_bus_lock(dev);
         device_lock(dev);
-        rc = __namespace_store(dev, attr, buf, len);
+        rc = nd_namespace_store(dev, &nd_btt->ndns, buf, len);
         dev_dbg(dev, "%s: result: %zd wrote: %s%s", __func__,
                         rc, buf, buf[len - 1] == '\n' ? "" : "\n");
         device_unlock(dev);
@@ -324,7 +185,7 @@ static struct device *__nd_btt_create(struct nd_region *nd_region,
         dev->type = &nd_btt_device_type;
         dev->groups = nd_btt_attribute_groups;
         device_initialize(&nd_btt->dev);
-        if (ndns && !__nd_btt_attach_ndns(nd_btt, ndns)) {
+        if (ndns && !__nd_attach_ndns(&nd_btt->dev, ndns, &nd_btt->ndns)) {
                 dev_dbg(&ndns->dev, "%s failed, already claimed by %s\n",
                                 __func__, dev_name(ndns->claim));
                 put_device(dev);
@@ -375,7 +236,7 @@ bool nd_btt_arena_is_valid(struct nd_btt *nd_btt, struct btt_sb *super)
 
         checksum = le64_to_cpu(super->checksum);
         super->checksum = 0;
-        if (checksum != nd_btt_sb_checksum(super))
+        if (checksum != nd_sb_checksum((struct nd_gen_sb *) super))
                 return false;
         super->checksum = cpu_to_le64(checksum);
 
@@ -387,25 +248,6 @@ bool nd_btt_arena_is_valid(struct nd_btt *nd_btt, struct btt_sb *super)
 }
 EXPORT_SYMBOL(nd_btt_arena_is_valid);
 
-/*
- * nd_btt_sb_checksum: compute checksum for btt info block
- *
- * Returns a fletcher64 checksum of everything in the given info block
- * except the last field (since that's where the checksum lives).
- */
-u64 nd_btt_sb_checksum(struct btt_sb *btt_sb)
-{
-        u64 sum;
-        __le64 sum_save;
-
-        sum_save = btt_sb->checksum;
-        btt_sb->checksum = 0;
-        sum = nd_fletcher64(btt_sb, sizeof(*btt_sb), 1);
-        btt_sb->checksum = sum_save;
-        return sum;
-}
-EXPORT_SYMBOL(nd_btt_sb_checksum);
-
 static int __nd_btt_probe(struct nd_btt *nd_btt,
                 struct nd_namespace_common *ndns, struct btt_sb *btt_sb)
 {
@@ -453,7 +295,9 @@ int nd_btt_probe(struct nd_namespace_common *ndns, void *drvdata)
         dev_dbg(&ndns->dev, "%s: btt: %s\n", __func__,
                         rc == 0 ? dev_name(dev) : "<none>");
         if (rc < 0) {
-                __nd_btt_detach_ndns(to_nd_btt(dev));
+                struct nd_btt *nd_btt = to_nd_btt(dev);
+
+                __nd_detach_ndns(dev, &nd_btt->ndns);
                 put_device(dev);
         }
 
diff --git a/drivers/nvdimm/claim.c b/drivers/nvdimm/claim.c
new file mode 100644
index 000000000000..e8f03b0e95e4
--- /dev/null
+++ b/drivers/nvdimm/claim.c
@@ -0,0 +1,201 @@
+/*
+ * Copyright(c) 2013-2015 Intel Corporation. All rights reserved.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ *
+ * 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.
+ */
+#include <linux/device.h>
+#include <linux/sizes.h>
+#include "nd-core.h"
+#include "pfn.h"
+#include "btt.h"
+#include "nd.h"
+
+void __nd_detach_ndns(struct device *dev, struct nd_namespace_common **_ndns)
+{
+        struct nd_namespace_common *ndns = *_ndns;
+
+        dev_WARN_ONCE(dev, !mutex_is_locked(&ndns->dev.mutex)
+                        || ndns->claim != dev,
+                        "%s: invalid claim\n", __func__);
+        ndns->claim = NULL;
+        *_ndns = NULL;
+        put_device(&ndns->dev);
+}
+
+void nd_detach_ndns(struct device *dev,
+                struct nd_namespace_common **_ndns)
+{
+        struct nd_namespace_common *ndns = *_ndns;
+
+        if (!ndns)
+                return;
+        get_device(&ndns->dev);
+        device_lock(&ndns->dev);
+        __nd_detach_ndns(dev, _ndns);
+        device_unlock(&ndns->dev);
+        put_device(&ndns->dev);
+}
+
+bool __nd_attach_ndns(struct device *dev, struct nd_namespace_common *attach,
+                struct nd_namespace_common **_ndns)
+{
+        if (attach->claim)
+                return false;
+        dev_WARN_ONCE(dev, !mutex_is_locked(&attach->dev.mutex)
+                        || *_ndns,
+                        "%s: invalid claim\n", __func__);
+        attach->claim = dev;
+        *_ndns = attach;
+        get_device(&attach->dev);
+        return true;
+}
+
+bool nd_attach_ndns(struct device *dev, struct nd_namespace_common *attach,
+                struct nd_namespace_common **_ndns)
+{
+        bool claimed;
+
+        device_lock(&attach->dev);
+        claimed = __nd_attach_ndns(dev, attach, _ndns);
+        device_unlock(&attach->dev);
+        return claimed;
+}
+
+static int namespace_match(struct device *dev, void *data)
+{
+        char *name = data;
+
+        return strcmp(name, dev_name(dev)) == 0;
+}
+
+static bool is_idle(struct device *dev, struct nd_namespace_common *ndns)
+{
+        struct nd_region *nd_region = to_nd_region(dev->parent);
+        struct device *seed = NULL;
+
+        if (is_nd_btt(dev))
+                seed = nd_region->btt_seed;
+        else if (is_nd_pfn(dev))
+                seed = nd_region->pfn_seed;
+
+        if (seed == dev || ndns || dev->driver)
+                return false;
+        return true;
+}
+
+static void nd_detach_and_reset(struct device *dev,
+                struct nd_namespace_common **_ndns)
+{
+        /* detach the namespace and destroy / reset the device */
+        nd_detach_ndns(dev, _ndns);
+        if (is_idle(dev, *_ndns)) {
+                nd_device_unregister(dev, ND_ASYNC);
+        } else if (is_nd_btt(dev)) {
+                struct nd_btt *nd_btt = to_nd_btt(dev);
+
+                nd_btt->lbasize = 0;
+                kfree(nd_btt->uuid);
+                nd_btt->uuid = NULL;
+        } else if (is_nd_pfn(dev)) {
+                struct nd_pfn *nd_pfn = to_nd_pfn(dev);
+
+                kfree(nd_pfn->uuid);
+                nd_pfn->uuid = NULL;
+                nd_pfn->mode = PFN_MODE_NONE;
+        }
+}
+
+ssize_t nd_namespace_store(struct device *dev,
+                struct nd_namespace_common **_ndns, const char *buf,
+                size_t len)
+{
+        struct nd_namespace_common *ndns;
+        struct device *found;
+        char *name;
+
+        if (dev->driver) {
+                dev_dbg(dev, "%s: -EBUSY\n", __func__);
+                return -EBUSY;
+        }
+
+        name = kstrndup(buf, len, GFP_KERNEL);
+        if (!name)
+                return -ENOMEM;
+        strim(name);
+
+        if (strncmp(name, "namespace", 9) == 0 || strcmp(name, "") == 0)
+                /* pass */;
+        else {
+                len = -EINVAL;
+                goto out;
+        }
+
+        ndns = *_ndns;
+        if (strcmp(name, "") == 0) {
+                nd_detach_and_reset(dev, _ndns);
+                goto out;
+        } else if (ndns) {
+                dev_dbg(dev, "namespace already set to: %s\n",
+                                dev_name(&ndns->dev));
+                len = -EBUSY;
+                goto out;
+        }
+
+        found = device_find_child(dev->parent, name, namespace_match);
+        if (!found) {
+                dev_dbg(dev, "'%s' not found under %s\n", name,
+                                dev_name(dev->parent));
+                len = -ENODEV;
+                goto out;
+        }
+
+        ndns = to_ndns(found);
+        if (__nvdimm_namespace_capacity(ndns) < SZ_16M) {
+                dev_dbg(dev, "%s too small to host\n", name);
+                len = -ENXIO;
+                goto out_attach;
+        }
+
+        WARN_ON_ONCE(!is_nvdimm_bus_locked(dev));
+        if (!nd_attach_ndns(dev, ndns, _ndns)) {
+                dev_dbg(dev, "%s already claimed\n",
+                                dev_name(&ndns->dev));
+                len = -EBUSY;
+        }
+
+ out_attach:
+        put_device(&ndns->dev); /* from device_find_child */
+ out:
+        kfree(name);
+        return len;
+}
+
+/*
+ * nd_sb_checksum: compute checksum for a generic info block
+ *
+ * Returns a fletcher64 checksum of everything in the given info block
+ * except the last field (since that's where the checksum lives).
+ */
+u64 nd_sb_checksum(struct nd_gen_sb *nd_gen_sb)
+{
+        u64 sum;
+        __le64 sum_save;
+
+        BUILD_BUG_ON(sizeof(struct btt_sb) != SZ_4K);
+        BUILD_BUG_ON(sizeof(struct nd_pfn_sb) != SZ_4K);
+        BUILD_BUG_ON(sizeof(struct nd_gen_sb) != SZ_4K);
+
+        sum_save = nd_gen_sb->checksum;
+        nd_gen_sb->checksum = 0;
+        sum = nd_fletcher64(nd_gen_sb, sizeof(*nd_gen_sb), 1);
+        nd_gen_sb->checksum = sum_save;
+        return sum;
+}
+EXPORT_SYMBOL(nd_sb_checksum);
diff --git a/drivers/nvdimm/namespace_devs.c b/drivers/nvdimm/namespace_devs.c
index b18ffea9d85b..9303ca29be9b 100644
--- a/drivers/nvdimm/namespace_devs.c
+++ b/drivers/nvdimm/namespace_devs.c
@@ -82,8 +82,16 @@ const char *nvdimm_namespace_disk_name(struct nd_namespace_common *ndns,
         struct nd_region *nd_region = to_nd_region(ndns->dev.parent);
         const char *suffix = "";
 
-        if (ndns->claim && is_nd_btt(ndns->claim))
-                suffix = "s";
+        if (ndns->claim) {
+                if (is_nd_btt(ndns->claim))
+                        suffix = "s";
+                else if (is_nd_pfn(ndns->claim))
+                        suffix = "m";
+                else
+                        dev_WARN_ONCE(&ndns->dev, 1,
+                                        "unknown claim type by %s\n",
+                                        dev_name(ndns->claim));
+        }
 
         if (is_namespace_pmem(&ndns->dev) || is_namespace_io(&ndns->dev))
                 sprintf(name, "pmem%d%s", nd_region->id, suffix);
@@ -1255,12 +1263,22 @@ static const struct attribute_group *nd_namespace_attribute_groups[] = {
 struct nd_namespace_common *nvdimm_namespace_common_probe(struct device *dev)
 {
         struct nd_btt *nd_btt = is_nd_btt(dev) ? to_nd_btt(dev) : NULL;
+        struct nd_pfn *nd_pfn = is_nd_pfn(dev) ? to_nd_pfn(dev) : NULL;
         struct nd_namespace_common *ndns;
         resource_size_t size;
 
-        if (nd_btt) {
-                ndns = nd_btt->ndns;
-                if (!ndns)
+        if (nd_btt || nd_pfn) {
+                struct device *host = NULL;
+
+                if (nd_btt) {
+                        host = &nd_btt->dev;
+                        ndns = nd_btt->ndns;
+                } else if (nd_pfn) {
+                        host = &nd_pfn->dev;
+                        ndns = nd_pfn->ndns;
+                }
+
+                if (!ndns || !host)
                         return ERR_PTR(-ENODEV);
 
                 /*
@@ -1271,12 +1289,12 @@ struct nd_namespace_common *nvdimm_namespace_common_probe(struct device *dev)
                 device_unlock(&ndns->dev);
                 if (ndns->dev.driver) {
                         dev_dbg(&ndns->dev, "is active, can't bind %s\n",
-                                        dev_name(&nd_btt->dev));
+                                        dev_name(host));
                         return ERR_PTR(-EBUSY);
                 }
-                if (dev_WARN_ONCE(&ndns->dev, ndns->claim != &nd_btt->dev,
+                if (dev_WARN_ONCE(&ndns->dev, ndns->claim != host,
                                         "host (%s) vs claim (%s) mismatch\n",
-                                        dev_name(&nd_btt->dev),
+                                        dev_name(host),
                                         dev_name(ndns->claim)))
                         return ERR_PTR(-ENXIO);
         } else {
diff --git a/drivers/nvdimm/nd-core.h b/drivers/nvdimm/nd-core.h
index e1970c71ad1c..159aed532042 100644
--- a/drivers/nvdimm/nd-core.h
+++ b/drivers/nvdimm/nd-core.h
@@ -80,4 +80,13 @@ struct resource *nsblk_add_resource(struct nd_region *nd_region,
 int nvdimm_num_label_slots(struct nvdimm_drvdata *ndd);
 void get_ndd(struct nvdimm_drvdata *ndd);
 resource_size_t __nvdimm_namespace_capacity(struct nd_namespace_common *ndns);
+void nd_detach_ndns(struct device *dev, struct nd_namespace_common **_ndns);
+void __nd_detach_ndns(struct device *dev, struct nd_namespace_common **_ndns);
+bool nd_attach_ndns(struct device *dev, struct nd_namespace_common *attach,
+                struct nd_namespace_common **_ndns);
+bool __nd_attach_ndns(struct device *dev, struct nd_namespace_common *attach,
+                struct nd_namespace_common **_ndns);
+ssize_t nd_namespace_store(struct device *dev,
+                struct nd_namespace_common **_ndns, const char *buf,
+                size_t len);
 #endif /* __ND_CORE_H__ */
diff --git a/drivers/nvdimm/nd.h b/drivers/nvdimm/nd.h
index f9615824947b..8da2be1cecb8 100644
--- a/drivers/nvdimm/nd.h
+++ b/drivers/nvdimm/nd.h
@@ -29,6 +29,13 @@ enum {
         ND_MAX_LANES = 256,
         SECTOR_SHIFT = 9,
         INT_LBASIZE_ALIGNMENT = 64,
+#if IS_ENABLED(CONFIG_NVDIMM_PFN)
+        ND_PFN_ALIGN = PAGES_PER_SECTION * PAGE_SIZE,
+        ND_PFN_MASK = ND_PFN_ALIGN - 1,
+#else
+        ND_PFN_ALIGN = 0,
+        ND_PFN_MASK = 0,
+#endif
 };
 
 struct nvdimm_drvdata {
@@ -92,8 +99,10 @@ struct nd_region {
         struct device dev;
         struct ida ns_ida;
         struct ida btt_ida;
+        struct ida pfn_ida;
         struct device *ns_seed;
         struct device *btt_seed;
+        struct device *pfn_seed;
         u16 ndr_mappings;
         u64 ndr_size;
         u64 ndr_start;
@@ -133,6 +142,22 @@ struct nd_btt {
         int id;
 };
 
+enum nd_pfn_mode {
+        PFN_MODE_NONE,
+        PFN_MODE_RAM,
+        PFN_MODE_PMEM,
+};
+
+struct nd_pfn {
+        int id;
+        u8 *uuid;
+        struct device dev;
+        unsigned long npfns;
+        enum nd_pfn_mode mode;
+        struct nd_pfn_sb *pfn_sb;
+        struct nd_namespace_common *ndns;
+};
+
 enum nd_async_mode {
         ND_SYNC,
         ND_ASYNC,
@@ -159,8 +184,13 @@ int nvdimm_init_config_data(struct nvdimm_drvdata *ndd);
 int nvdimm_set_config_data(struct nvdimm_drvdata *ndd, size_t offset,
                 void *buf, size_t len);
 struct nd_btt *to_nd_btt(struct device *dev);
-struct btt_sb;
-u64 nd_btt_sb_checksum(struct btt_sb *btt_sb);
+
+struct nd_gen_sb {
+        char reserved[SZ_4K - 8];
+        __le64 checksum;
+};
+
+u64 nd_sb_checksum(struct nd_gen_sb *sb);
 #if IS_ENABLED(CONFIG_BTT)
 int nd_btt_probe(struct nd_namespace_common *ndns, void *drvdata);
 bool is_nd_btt(struct device *dev);
@@ -180,8 +210,30 @@ static inline struct device *nd_btt_create(struct nd_region *nd_region)
 {
         return NULL;
 }
+#endif
 
+struct nd_pfn *to_nd_pfn(struct device *dev);
+#if IS_ENABLED(CONFIG_NVDIMM_PFN)
+int nd_pfn_probe(struct nd_namespace_common *ndns, void *drvdata);
+bool is_nd_pfn(struct device *dev);
+struct device *nd_pfn_create(struct nd_region *nd_region);
+#else
+static inline int nd_pfn_probe(struct nd_namespace_common *ndns, void *drvdata)
+{
+        return -ENODEV;
+}
+
+static inline bool is_nd_pfn(struct device *dev)
+{
+        return false;
+}
+
+static inline struct device *nd_pfn_create(struct nd_region *nd_region)
+{
+        return NULL;
+}
 #endif
+
 struct nd_region *to_nd_region(struct device *dev);
 int nd_region_to_nstype(struct nd_region *nd_region);
 int nd_region_register_namespaces(struct nd_region *nd_region, int *err);
diff --git a/drivers/nvdimm/pfn.h b/drivers/nvdimm/pfn.h
new file mode 100644
index 000000000000..cc243754acef
--- /dev/null
+++ b/drivers/nvdimm/pfn.h
@@ -0,0 +1,35 @@
+/*
+ * Copyright (c) 2014-2015, Intel Corporation.
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms and conditions of the GNU General Public License,
+ * version 2, as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope 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.
+ */
+
+#ifndef __NVDIMM_PFN_H
+#define __NVDIMM_PFN_H
+
+#include <linux/types.h>
+
+#define PFN_SIG_LEN 16
+#define PFN_SIG "NVDIMM_PFN_INFO\0"
+
+struct nd_pfn_sb {
+        u8 signature[PFN_SIG_LEN];
+        u8 uuid[16];
+        u8 parent_uuid[16];
+        __le32 flags;
+        __le16 version_major;
+        __le16 version_minor;
+        __le64 dataoff;
+        __le64 npfns;
+        __le32 mode;
+        u8 padding[4012];
+        __le64 checksum;
+};
+#endif /* __NVDIMM_PFN_H */
diff --git a/drivers/nvdimm/pfn_devs.c b/drivers/nvdimm/pfn_devs.c
new file mode 100644
index 000000000000..f708d63709a5
--- /dev/null
+++ b/drivers/nvdimm/pfn_devs.c
@@ -0,0 +1,336 @@
+/*
+ * Copyright(c) 2013-2015 Intel Corporation. All rights reserved.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ *
+ * 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.
+ */
+#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, "%s\n", __func__);
+        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);
+}
+
+static struct device_type nd_pfn_device_type = {
+        .name = "nd_pfn",
+        .release = nd_pfn_release,
+};
+
+bool is_nd_pfn(struct device *dev)
+{
+        return dev ? dev->type == &nd_pfn_device_type : false;
+}
+EXPORT_SYMBOL(is_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(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(dev);
+        ssize_t rc = 0;
+
+        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) {
+                        /* TODO: allocate from PMEM support */
+                        rc = -ENOTTY;
+                } 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, "%s: result: %zd wrote: %s%s", __func__,
+                        rc, buf, buf[len - 1] == '\n' ? "" : "\n");
+        nvdimm_bus_unlock(dev);
+        device_unlock(dev);
+
+        return rc ? rc : len;
+}
+static DEVICE_ATTR_RW(mode);
+
+static ssize_t uuid_show(struct device *dev,
+                struct device_attribute *attr, char *buf)
+{
+        struct nd_pfn *nd_pfn = to_nd_pfn(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(dev);
+        ssize_t rc;
+
+        device_lock(dev);
+        rc = nd_uuid_store(dev, &nd_pfn->uuid, buf, len);
+        dev_dbg(dev, "%s: result: %zd wrote: %s%s", __func__,
+                        rc, buf, buf[len - 1] == '\n' ? "" : "\n");
+        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(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(dev);
+        ssize_t rc;
+
+        nvdimm_bus_lock(dev);
+        device_lock(dev);
+        rc = nd_namespace_store(dev, &nd_pfn->ndns, buf, len);
+        dev_dbg(dev, "%s: result: %zd wrote: %s%s", __func__,
+                        rc, buf, buf[len - 1] == '\n' ? "" : "\n");
+        device_unlock(dev);
+        nvdimm_bus_unlock(dev);
+
+        return rc;
+}
+static DEVICE_ATTR_RW(namespace);
+
+static struct attribute *nd_pfn_attributes[] = {
+        &dev_attr_mode.attr,
+        &dev_attr_namespace.attr,
+        &dev_attr_uuid.attr,
+        NULL,
+};
+
+static struct attribute_group nd_pfn_attribute_group = {
+        .attrs = nd_pfn_attributes,
+};
+
+static const struct attribute_group *nd_pfn_attribute_groups[] = {
+        &nd_pfn_attribute_group,
+        &nd_device_attribute_group,
+        &nd_numa_attribute_group,
+        NULL,
+};
+
+static struct device *__nd_pfn_create(struct nd_region *nd_region,
+                u8 *uuid, enum nd_pfn_mode mode,
+                struct nd_namespace_common *ndns)
+{
+        struct nd_pfn *nd_pfn;
+        struct device *dev;
+
+        /* we can only create pages for contiguous ranged of pmem */
+        if (!is_nd_pmem(&nd_region->dev))
+                return NULL;
+
+        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;
+        }
+
+        nd_pfn->mode = mode;
+        if (uuid)
+                uuid = kmemdup(uuid, 16, GFP_KERNEL);
+        nd_pfn->uuid = uuid;
+        dev = &nd_pfn->dev;
+        dev_set_name(dev, "pfn%d.%d", nd_region->id, nd_pfn->id);
+        dev->parent = &nd_region->dev;
+        dev->type = &nd_pfn_device_type;
+        dev->groups = nd_pfn_attribute_groups;
+        device_initialize(&nd_pfn->dev);
+        if (ndns && !__nd_attach_ndns(&nd_pfn->dev, ndns, &nd_pfn->ndns)) {
+                dev_dbg(&ndns->dev, "%s failed, already claimed by %s\n",
+                                __func__, dev_name(ndns->claim));
+                put_device(dev);
+                return NULL;
+        }
+        return dev;
+}
+
+struct device *nd_pfn_create(struct nd_region *nd_region)
+{
+        struct device *dev = __nd_pfn_create(nd_region, NULL, PFN_MODE_NONE,
+                        NULL);
+
+        if (dev)
+                __nd_device_register(dev);
+        return dev;
+}
+
+static int nd_pfn_validate(struct nd_pfn *nd_pfn)
+{
+        struct nd_namespace_common *ndns = nd_pfn->ndns;
+        struct nd_pfn_sb *pfn_sb = nd_pfn->pfn_sb;
+        struct nd_namespace_io *nsio;
+        u64 checksum, offset;
+
+        if (!pfn_sb || !ndns)
+                return -ENODEV;
+
+        if (!is_nd_pmem(nd_pfn->dev.parent))
+                return -ENODEV;
+
+        /* section alignment for simple hotplug */
+        if (nvdimm_namespace_capacity(ndns) < ND_PFN_ALIGN)
+                return -ENODEV;
+
+        if (nvdimm_read_bytes(ndns, SZ_4K, pfn_sb, sizeof(*pfn_sb)))
+                return -ENXIO;
+
+        if (memcmp(pfn_sb->signature, PFN_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);
+
+        switch (le32_to_cpu(pfn_sb->mode)) {
+        case PFN_MODE_RAM:
+                break;
+        case PFN_MODE_PMEM:
+                /* TODO: allocate from PMEM support */
+                return -ENOTTY;
+        default:
+                return -ENXIO;
+        }
+
+        if (!nd_pfn->uuid) {
+                /* from probe we allocate */
+                nd_pfn->uuid = kmemdup(pfn_sb->uuid, 16, GFP_KERNEL);
+                if (!nd_pfn->uuid)
+                        return -ENOMEM;
+        } else {
+                /* from init we validate */
+                if (memcmp(nd_pfn->uuid, pfn_sb->uuid, 16) != 0)
+                        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.
+         */
+        offset = le64_to_cpu(pfn_sb->dataoff);
+        nsio = to_nd_namespace_io(&ndns->dev);
+        if ((nsio->res.start + offset) & (ND_PFN_ALIGN - 1)) {
+                dev_err(&nd_pfn->dev,
+                                "init failed: %s with offset %#llx not section aligned\n",
+                                dev_name(&ndns->dev), offset);
+                return -EBUSY;
+        } else 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;
+        }
+
+        return 0;
+}
+
+int nd_pfn_probe(struct nd_namespace_common *ndns, void *drvdata)
+{
+        int rc;
+        struct device *dev;
+        struct nd_pfn *nd_pfn;
+        struct nd_pfn_sb *pfn_sb;
+        struct nd_region *nd_region = to_nd_region(ndns->dev.parent);
+
+        if (ndns->force_raw)
+                return -ENODEV;
+
+        nvdimm_bus_lock(&ndns->dev);
+        dev = __nd_pfn_create(nd_region, NULL, PFN_MODE_NONE, ndns);
+        nvdimm_bus_unlock(&ndns->dev);
+        if (!dev)
+                return -ENOMEM;
+        dev_set_drvdata(dev, drvdata);
+        pfn_sb = kzalloc(sizeof(*pfn_sb), GFP_KERNEL);
+        nd_pfn = to_nd_pfn(dev);
+        nd_pfn->pfn_sb = pfn_sb;
+        rc = nd_pfn_validate(nd_pfn);
+        nd_pfn->pfn_sb = NULL;
+        kfree(pfn_sb);
+        dev_dbg(&ndns->dev, "%s: pfn: %s\n", __func__,
+                        rc == 0 ? dev_name(dev) : "<none>");
+        if (rc < 0) {
+                __nd_detach_ndns(dev, &nd_pfn->ndns);
+                put_device(dev);
+        } else
+                __nd_device_register(&nd_pfn->dev);
+
+        return rc;
+}
+EXPORT_SYMBOL(nd_pfn_probe);
diff --git a/drivers/nvdimm/region.c b/drivers/nvdimm/region.c
index f28f78ccff19..7da63eac78ee 100644
--- a/drivers/nvdimm/region.c
+++ b/drivers/nvdimm/region.c
@@ -53,6 +53,7 @@ static int nd_region_probe(struct device *dev)
                 return -ENODEV;
 
         nd_region->btt_seed = nd_btt_create(nd_region);
+        nd_region->pfn_seed = nd_pfn_create(nd_region);
         if (err == 0)
                 return 0;
 
@@ -84,6 +85,7 @@ static int nd_region_remove(struct device *dev)
         nvdimm_bus_lock(dev);
         nd_region->ns_seed = NULL;
         nd_region->btt_seed = NULL;
+        nd_region->pfn_seed = NULL;
         dev_set_drvdata(dev, NULL);
         nvdimm_bus_unlock(dev);
 
diff --git a/drivers/nvdimm/region_devs.c b/drivers/nvdimm/region_devs.c
index 7384455792bf..da4338154ad2 100644
--- a/drivers/nvdimm/region_devs.c
+++ b/drivers/nvdimm/region_devs.c
@@ -345,6 +345,23 @@ static ssize_t btt_seed_show(struct device *dev,
 }
 static DEVICE_ATTR_RO(btt_seed);
 
+static ssize_t pfn_seed_show(struct device *dev,
+                struct device_attribute *attr, char *buf)
+{
+        struct nd_region *nd_region = to_nd_region(dev);
+        ssize_t rc;
+
+        nvdimm_bus_lock(dev);
+        if (nd_region->pfn_seed)
+                rc = sprintf(buf, "%s\n", dev_name(nd_region->pfn_seed));
+        else
+                rc = sprintf(buf, "\n");
+        nvdimm_bus_unlock(dev);
+
+        return rc;
+}
+static DEVICE_ATTR_RO(pfn_seed);
+
 static ssize_t read_only_show(struct device *dev,
                 struct device_attribute *attr, char *buf)
 {
@@ -373,6 +390,7 @@ static struct attribute *nd_region_attributes[] = {
         &dev_attr_nstype.attr,
         &dev_attr_mappings.attr,
         &dev_attr_btt_seed.attr,
+        &dev_attr_pfn_seed.attr,
         &dev_attr_read_only.attr,
         &dev_attr_set_cookie.attr,
         &dev_attr_available_size.attr,
@@ -744,6 +762,7 @@ static struct nd_region *nd_region_create(struct nvdimm_bus *nvdimm_bus,
         nd_region->numa_node = ndr_desc->numa_node;
         ida_init(&nd_region->ns_ida);
         ida_init(&nd_region->btt_ida);
+        ida_init(&nd_region->pfn_ida);
         dev = &nd_region->dev;
         dev_set_name(dev, "region%d", nd_region->id);
         dev->parent = &nvdimm_bus->dev;
diff --git a/tools/testing/nvdimm/Kbuild b/tools/testing/nvdimm/Kbuild
index 98f2881ba6a2..99e70f0729be 100644
--- a/tools/testing/nvdimm/Kbuild
+++ b/tools/testing/nvdimm/Kbuild
@@ -43,7 +43,9 @@ libnvdimm-y += $(NVDIMM_SRC)/region_devs.o
 libnvdimm-y += $(NVDIMM_SRC)/region.o
 libnvdimm-y += $(NVDIMM_SRC)/namespace_devs.o
 libnvdimm-y += $(NVDIMM_SRC)/label.o
+libnvdimm-$(CONFIG_ND_CLAIM) += $(NVDIMM_SRC)/claim.o
 libnvdimm-$(CONFIG_BTT) += $(NVDIMM_SRC)/btt_devs.o
+libnvdimm-$(CONFIG_NVDIMM_PFN) += $(NVDIMM_SRC)/pfn_devs.o
 libnvdimm-y += config_check.o
 
 obj-m += test/