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

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Message-Id: <20250917134116.1623730-21-s.neeraj@samsung.com>
Date: Wed, 17 Sep 2025 19:11:16 +0530
From: Neeraj Kumar <s.neeraj@...sung.com>
To: linux-cxl@...r.kernel.org, nvdimm@...ts.linux.dev,
	linux-kernel@...r.kernel.org, gost.dev@...sung.com
Cc: a.manzanares@...sung.com, vishak.g@...sung.com, neeraj.kernel@...il.com,
	cpgs@...sung.com, Neeraj Kumar <s.neeraj@...sung.com>
Subject: [PATCH V3 20/20] cxl/pmem: Add CXL LSA 2.1 support in cxl pmem

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@...sung.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