libnvdimm: add an api to cast a 'struct nd_region' to its 'struct device'

For debug, it is useful for bus providers to be able to retrieve the
'struct device' associated with an nd_region instance that it
registered. We already have to_nd_region() to perform the reverse cast
operation, in fact its duplicate declaration can be removed from the
private drivers/nvdimm/nd.h header.

Reviewed-by: Dave Jiang <dave.jiang@intel.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>

1 files changed, 1 insertions, 0 deletions

diff --git a/include/linux/libnvdimm.h b/include/linux/libnvdimm.h
index ff855ed965fb..e0684a678a1b 100644
--- a/include/linux/libnvdimm.h
+++ b/include/linux/libnvdimm.h
@@ -164,6 +164,7 @@ void nvdimm_bus_unregister(struct nvdimm_bus *nvdimm_bus);
 struct nvdimm_bus *to_nvdimm_bus(struct device *dev);
 struct nvdimm *to_nvdimm(struct device *dev);
 struct nd_region *to_nd_region(struct device *dev);
+struct device *nd_region_dev(struct nd_region *nd_region);
 struct nd_blk_region *to_nd_blk_region(struct device *dev);
 struct nvdimm_bus_descriptor *to_nd_desc(struct nvdimm_bus *nvdimm_bus);
 struct device *to_nvdimm_bus_dev(struct nvdimm_bus *nvdimm_bus);