libnvdimm: support for legacy (non-aliasing) nvdimms

The libnvdimm region driver is an intermediary driver that translates
non-volatile "region"s into "namespace" sub-devices that are surfaced by
persistent memory block-device drivers (PMEM and BLK).

ACPI 6 introduces the concept that a given nvdimm may simultaneously
offer multiple access modes to its media through direct PMEM load/store
access, or windowed BLK mode.  Existing nvdimms mostly implement a PMEM
interface, some offer a BLK-like mode, but never both as ACPI 6 defines.
If an nvdimm is single interfaced, then there is no need for dimm
metadata labels.  For these devices we can take the region boundaries
directly to create a child namespace device (nd_namespace_io).

Acked-by: Christoph Hellwig <hch@lst.de>
Tested-by: Toshi Kani <toshi.kani@hp.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>

include/uapi/linux/ndctl.h

@@ -177,8 +177,18 @@ static inline const char *nvdimm_cmd_name(unsigned cmd)
 
 
 #define ND_DEVICE_DIMM 1            /* nd_dimm: container for "config data" */
+#define ND_DEVICE_REGION_PMEM 2     /* nd_region: (parent of PMEM namespaces) */
+#define ND_DEVICE_REGION_BLK 3      /* nd_region: (parent of BLK namespaces) */
+#define ND_DEVICE_NAMESPACE_IO 4    /* legacy persistent memory */
+#define ND_DEVICE_NAMESPACE_PMEM 5  /* PMEM namespace (may alias with BLK) */
+#define ND_DEVICE_NAMESPACE_BLK 6   /* BLK namespace (may alias with PMEM) */
 
 enum nd_driver_flags {
 	ND_DRIVER_DIMM            = 1 << ND_DEVICE_DIMM,
+	ND_DRIVER_REGION_PMEM     = 1 << ND_DEVICE_REGION_PMEM,
+	ND_DRIVER_REGION_BLK      = 1 << ND_DEVICE_REGION_BLK,
+	ND_DRIVER_NAMESPACE_IO    = 1 << ND_DEVICE_NAMESPACE_IO,
+	ND_DRIVER_NAMESPACE_PMEM  = 1 << ND_DEVICE_NAMESPACE_PMEM,
+	ND_DRIVER_NAMESPACE_BLK   = 1 << ND_DEVICE_NAMESPACE_BLK,
 };
 #endif /* __NDCTL_H__ */