[PATCH V3 20/20] cxl/pmem: Add CXL LSA 2.1 support in cxl pmem

Neeraj Kumar
2025-09-17T13:31:02Z

Add support of CXL LSA 2.1 using NDD_REGION_LABELING flag. It creates
cxl region based on region information parsed from LSA.

Signed-off-by: Neeraj Kumar <s.neeraj@samsung.com>
---
drivers/cxl/core/pmem_region.c | 53 ++++++++++++++++++++++++++++++++++
drivers/cxl/cxl.h | 4 +++
drivers/cxl/pmem.c | 2 ++
3 files changed, 59 insertions(+)

diff --git a/drivers/cxl/core/pmem_region.c b/drivers/cxl/core/pmem_region.c
index 665b603c907b..3ef9c7d15041 100644
--- a/drivers/cxl/core/pmem_region.c
+++ b/drivers/cxl/core/pmem_region.c
@@ -290,3 +290,56 @@ int devm_cxl_add_pmem_region(struct cxl_region *cxlr)
return rc;
}
EXPORT_SYMBOL_NS_GPL(devm_cxl_add_pmem_region, "CXL");
+
+static int match_free_ep_decoder(struct device *dev, const void *data)
+{
+ struct cxl_decoder *cxld = to_cxl_decoder(dev);
+
+ return !cxld->region;
+}
+
+static struct cxl_decoder *cxl_find_free_ep_decoder(struct cxl_port *port)
+{
+ struct device *dev;
+
+ dev = device_find_child(&port->dev, NULL, match_free_ep_decoder);
+ if (!dev)
+ return NULL;
+
+ /* Release device ref taken via device_find_child() */
+ put_device(dev);
+ return to_cxl_decoder(dev);
+}
+
+void create_pmem_region(struct nvdimm *nvdimm)
+{
+ struct cxl_nvdimm *cxl_nvd;
+ struct cxl_memdev *cxlmd;
+ struct cxl_pmem_region_params *params;
+ struct cxl_root_decoder *cxlrd;
+ struct cxl_decoder *cxld;
+ struct cxl_region *cxlr;
+
+ if (!nvdimm_has_cxl_region(nvdimm))
+ return;
+
+ lockdep_assert_held(&cxl_rwsem.region);
+ cxl_nvd = nvdimm_provider_data(nvdimm);
+ params = nvdimm_get_cxl_region_param(nvdimm);
+ cxlmd = cxl_nvd->cxlmd;
+ cxlrd = cxlmd->cxlrd;
+
+ /* TODO: Region creation support only for interleave way == 1 */
+ if (!(params->nlabel == 1))
+ dev_info(&cxlmd->dev,
+ "Region Creation is not supported with iw > 1\n");
+ else {
+ cxld = cxl_find_free_ep_decoder(cxlmd->endpoint);
+ cxlr = cxl_create_region(cxlrd, CXL_PARTMODE_PMEM,
+ atomic_read(&cxlrd->region_id),
+ params, cxld);
+ if (IS_ERR(cxlr))
+ dev_info(&cxlmd->dev, "Region Creation failed\n");
+ }
+}
+EXPORT_SYMBOL_NS_GPL(create_pmem_region, "CXL");
diff --git a/drivers/cxl/cxl.h b/drivers/cxl/cxl.h
index f01f8c942fdf..0a87ea79742a 100644
--- a/drivers/cxl/cxl.h
+++ b/drivers/cxl/cxl.h
@@ -910,6 +910,7 @@ cxl_create_region(struct cxl_root_decoder *cxlrd,
bool is_cxl_pmem_region(struct device *dev);
struct cxl_pmem_region *to_cxl_pmem_region(struct device *dev);
int devm_cxl_add_pmem_region(struct cxl_region *cxlr);
+void create_pmem_region(struct nvdimm *nvdimm);
#else
static inline bool is_cxl_pmem_region(struct device *dev)
{
@@ -923,6 +924,9 @@ static inline int devm_cxl_add_pmem_region(struct cxl_region *cxlr)
{
return 0;
}
+static inline void create_pmem_region(struct nvdimm *nvdimm)
+{
+}
#endif

void cxl_endpoint_parse_cdat(struct cxl_port *port);
diff --git a/drivers/cxl/pmem.c b/drivers/cxl/pmem.c
index 38a5bcdc68ce..0cdef01dbc68 100644
--- a/drivers/cxl/pmem.c
+++ b/drivers/cxl/pmem.c
@@ -135,6 +135,7 @@ static int cxl_nvdimm_probe(struct device *dev)
return rc;

set_bit(NDD_LABELING, &flags);
+ set_bit(NDD_REGION_LABELING, &flags);
set_bit(NDD_REGISTER_SYNC, &flags);
set_bit(ND_CMD_GET_CONFIG_SIZE, &cmd_mask);
set_bit(ND_CMD_GET_CONFIG_DATA, &cmd_mask);
@@ -155,6 +156,7 @@ static int cxl_nvdimm_probe(struct device *dev)
return -ENOMEM;

dev_set_drvdata(dev, nvdimm);
+ create_pmem_region(nvdimm);
return devm_add_action_or_reset(dev, unregister_nvdimm, nvdimm);
}

--
2.34.1