libnvdimm, nfit: regions (block-data-window, persistent memory, volatile memory)

A "region" device represents the maximum capacity of a BLK range (mmio
block-data-window(s)), or a PMEM range (DAX-capable persistent memory or
volatile memory), without regard for aliasing.  Aliasing, in the
dimm-local address space (DPA), is resolved by metadata on a dimm to
designate which exclusive interface will access the aliased DPA ranges.
Support for the per-dimm metadata/label arrvies is in a subsequent
patch.

The name format of "region" devices is "regionN" where, like dimms, N is
a global ida index assigned at discovery time.  This id is not reliable
across reboots nor in the presence of hotplug.  Look to attributes of
the region or static id-data of the sub-namespace to generate a
persistent name.  However, if the platform configuration does not change
it is reasonable to expect the same region id to be assigned at the next
boot.

"region"s have 2 generic attributes "size", and "mapping"s where:
- size: the BLK accessible capacity or the span of the
  system physical address range in the case of PMEM.

- mappingN: a tuple describing a dimm's contribution to the region's
  capacity in the format (<nmemX>,<dpa>,<size>).  For a PMEM-region
  there will be at least one mapping per dimm in the interleave set.  For
  a BLK-region there is only "mapping0" listing the starting DPA of the
  BLK-region and the available DPA capacity of that space (matches "size"
  above).

The max number of mappings per "region" is hard coded per the
constraints of sysfs attribute groups.  That said the number of mappings
per region should never exceed the maximum number of possible dimms in
the system.  If the current number turns out to not be enough then the
"mappings" attribute clarifies how many there are supposed to be. "32
should be enough for anybody...".

Cc: Neil Brown <neilb@suse.de>
Cc: <linux-acpi@vger.kernel.org>
Cc: Greg KH <gregkh@linuxfoundation.org>
Cc: Robert Moore <robert.moore@intel.com>
Cc: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Acked-by: Christoph Hellwig <hch@lst.de>
Acked-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Tested-by: Toshi Kani <toshi.kani@hp.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>

1 files changed, 3 insertions, 0 deletions

diff --git a/drivers/nvdimm/nd-core.h b/drivers/nvdimm/nd-core.h
index f2004b790874..1d760bf24857 100644
--- a/drivers/nvdimm/nd-core.h
+++ b/drivers/nvdimm/nd-core.h
@@ -40,5 +40,8 @@ void nvdimm_bus_exit(void);
 int nvdimm_bus_create_ndctl(struct nvdimm_bus *nvdimm_bus);
 void nvdimm_bus_destroy_ndctl(struct nvdimm_bus *nvdimm_bus);
 void nd_synchronize(void);
+int nvdimm_bus_register_dimms(struct nvdimm_bus *nvdimm_bus);
+int nvdimm_bus_register_regions(struct nvdimm_bus *nvdimm_bus);
+int nd_match_dimm(struct device *dev, void *data);
 bool is_nvdimm(struct device *dev);
 #endif /* __ND_CORE_H__ */