v4.19.13 snapshot.
diff --git a/drivers/dax/pmem.c b/drivers/dax/pmem.c
new file mode 100644
index 0000000..99e2aac
--- /dev/null
+++ b/drivers/dax/pmem.c
@@ -0,0 +1,161 @@
+/*
+ * Copyright(c) 2016 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/percpu-refcount.h>
+#include <linux/memremap.h>
+#include <linux/module.h>
+#include <linux/pfn_t.h>
+#include "../nvdimm/pfn.h"
+#include "../nvdimm/nd.h"
+#include "device-dax.h"
+
+struct dax_pmem {
+ struct device *dev;
+ struct percpu_ref ref;
+ struct dev_pagemap pgmap;
+ struct completion cmp;
+};
+
+static struct dax_pmem *to_dax_pmem(struct percpu_ref *ref)
+{
+ return container_of(ref, struct dax_pmem, ref);
+}
+
+static void dax_pmem_percpu_release(struct percpu_ref *ref)
+{
+ struct dax_pmem *dax_pmem = to_dax_pmem(ref);
+
+ dev_dbg(dax_pmem->dev, "trace\n");
+ complete(&dax_pmem->cmp);
+}
+
+static void dax_pmem_percpu_exit(void *data)
+{
+ struct percpu_ref *ref = data;
+ struct dax_pmem *dax_pmem = to_dax_pmem(ref);
+
+ dev_dbg(dax_pmem->dev, "trace\n");
+ wait_for_completion(&dax_pmem->cmp);
+ percpu_ref_exit(ref);
+}
+
+static void dax_pmem_percpu_kill(void *data)
+{
+ struct percpu_ref *ref = data;
+ struct dax_pmem *dax_pmem = to_dax_pmem(ref);
+
+ dev_dbg(dax_pmem->dev, "trace\n");
+ percpu_ref_kill(ref);
+}
+
+static int dax_pmem_probe(struct device *dev)
+{
+ void *addr;
+ struct resource res;
+ int rc, id, region_id;
+ struct nd_pfn_sb *pfn_sb;
+ struct dev_dax *dev_dax;
+ struct dax_pmem *dax_pmem;
+ struct nd_namespace_io *nsio;
+ struct dax_region *dax_region;
+ struct nd_namespace_common *ndns;
+ struct nd_dax *nd_dax = to_nd_dax(dev);
+ struct nd_pfn *nd_pfn = &nd_dax->nd_pfn;
+
+ ndns = nvdimm_namespace_common_probe(dev);
+ if (IS_ERR(ndns))
+ return PTR_ERR(ndns);
+ nsio = to_nd_namespace_io(&ndns->dev);
+
+ dax_pmem = devm_kzalloc(dev, sizeof(*dax_pmem), GFP_KERNEL);
+ if (!dax_pmem)
+ return -ENOMEM;
+
+ /* parse the 'pfn' info block via ->rw_bytes */
+ rc = devm_nsio_enable(dev, nsio);
+ if (rc)
+ return rc;
+ rc = nvdimm_setup_pfn(nd_pfn, &dax_pmem->pgmap);
+ if (rc)
+ return rc;
+ devm_nsio_disable(dev, nsio);
+
+ pfn_sb = nd_pfn->pfn_sb;
+
+ if (!devm_request_mem_region(dev, nsio->res.start,
+ resource_size(&nsio->res),
+ dev_name(&ndns->dev))) {
+ dev_warn(dev, "could not reserve region %pR\n", &nsio->res);
+ return -EBUSY;
+ }
+
+ dax_pmem->dev = dev;
+ init_completion(&dax_pmem->cmp);
+ rc = percpu_ref_init(&dax_pmem->ref, dax_pmem_percpu_release, 0,
+ GFP_KERNEL);
+ if (rc)
+ return rc;
+
+ rc = devm_add_action(dev, dax_pmem_percpu_exit, &dax_pmem->ref);
+ if (rc) {
+ percpu_ref_exit(&dax_pmem->ref);
+ return rc;
+ }
+
+ dax_pmem->pgmap.ref = &dax_pmem->ref;
+ addr = devm_memremap_pages(dev, &dax_pmem->pgmap);
+ if (IS_ERR(addr)) {
+ devm_remove_action(dev, dax_pmem_percpu_exit, &dax_pmem->ref);
+ percpu_ref_exit(&dax_pmem->ref);
+ return PTR_ERR(addr);
+ }
+
+ rc = devm_add_action_or_reset(dev, dax_pmem_percpu_kill,
+ &dax_pmem->ref);
+ if (rc)
+ return rc;
+
+ /* adjust the dax_region resource to the start of data */
+ memcpy(&res, &dax_pmem->pgmap.res, sizeof(res));
+ res.start += le64_to_cpu(pfn_sb->dataoff);
+
+ rc = sscanf(dev_name(&ndns->dev), "namespace%d.%d", ®ion_id, &id);
+ if (rc != 2)
+ return -EINVAL;
+
+ dax_region = alloc_dax_region(dev, region_id, &res,
+ le32_to_cpu(pfn_sb->align), addr, PFN_DEV|PFN_MAP);
+ if (!dax_region)
+ return -ENOMEM;
+
+ /* TODO: support for subdividing a dax region... */
+ dev_dax = devm_create_dev_dax(dax_region, id, &res, 1);
+
+ /* child dev_dax instances now own the lifetime of the dax_region */
+ dax_region_put(dax_region);
+
+ return PTR_ERR_OR_ZERO(dev_dax);
+}
+
+static struct nd_device_driver dax_pmem_driver = {
+ .probe = dax_pmem_probe,
+ .drv = {
+ .name = "dax_pmem",
+ },
+ .type = ND_DRIVER_DAX_PMEM,
+};
+
+module_nd_driver(dax_pmem_driver);
+
+MODULE_LICENSE("GPL v2");
+MODULE_AUTHOR("Intel Corporation");
+MODULE_ALIAS_ND_DEVICE(ND_DEVICE_DAX_PMEM);