powerpc/pseries/scm: Mark the region volatile if cache flush not required

The device tree node is documented as below:

  “ibm,cache-flush-required”:
  property name indicates Cache Flush Required for this Persistent Memory Segment to persist memory
  prop-encoded-array: None, this is a name only property.
Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

arch/powerpc/platforms/pseries/papr_scm.c

@@ -28,6 +28,7 @@ struct papr_scm_priv {
 	uint64_t blocks;
 	uint64_t block_size;
 	int metadata_size;
+	bool is_volatile;
 
 	uint64_t bound_addr;
 
@@ -248,6 +249,9 @@ static int papr_scm_nvdimm_init(struct papr_scm_priv *p)
 	ndr_desc.nd_set = &p->nd_set;
 	set_bit(ND_REGION_PAGEMAP, &ndr_desc.flags);
 
+	if (p->is_volatile)
+		p->region = nvdimm_volatile_region_create(p->bus, &ndr_desc);
+	else
 		p->region = nvdimm_pmem_region_create(p->bus, &ndr_desc);
 	if (!p->region) {
 		dev_err(dev, "Error registering region %pR from %pOF\n",
@@ -293,6 +297,7 @@ static int papr_scm_probe(struct platform_device *pdev)
 		return -ENODEV;
 	}
 
+
 	p = kzalloc(sizeof(*p), GFP_KERNEL);
 	if (!p)
 		return -ENOMEM;
@@ -304,6 +309,7 @@ static int papr_scm_probe(struct platform_device *pdev)
 	p->drc_index = drc_index;
 	p->block_size = block_size;
 	p->blocks = blocks;
+	p->is_volatile = !of_property_read_bool(dn, "ibm,cache-flush-required");
 
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