linux-kernel - [RFC PATCH 18/20] cxl/pmem: Add support of cxl lsa 2.1 support in cxl pmem

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Message-Id: <592959754.121750165383213.JavaMail.epsvc@epcpadp2new>
Date: Tue, 17 Jun 2025 18:09:42 +0530
From: Neeraj Kumar <s.neeraj@...sung.com>
To: dan.j.williams@...el.com, dave@...olabs.net,
	jonathan.cameron@...wei.com, dave.jiang@...el.com,
	alison.schofield@...el.com, vishal.l.verma@...el.com, ira.weiny@...el.com
Cc: a.manzanares@...sung.com, nifan.cxl@...il.com, anisa.su@...sung.com,
	vishak.g@...sung.com, krish.reddy@...sung.com, arun.george@...sung.com,
	alok.rathore@...sung.com, s.neeraj@...sung.com, neeraj.kernel@...il.com,
	linux-kernel@...r.kernel.org, linux-cxl@...r.kernel.org,
	nvdimm@...ts.linux.dev, gost.dev@...sung.com, cpgs@...sung.com
Subject: [RFC PATCH 18/20] cxl/pmem: Add support of cxl lsa 2.1 support in
 cxl pmem

Add support of cxl lsa 2.1 using NDD_CXL_LABEL flag. It also creates cxl
region based on region information parsed from LSA.

Signed-off-by: Neeraj Kumar <s.neeraj@...sung.com>
---
 drivers/cxl/pmem.c | 59 ++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 59 insertions(+)

diff --git a/drivers/cxl/pmem.c b/drivers/cxl/pmem.c
index ffcebb8d382f..2733d79b32d5 100644
--- a/drivers/cxl/pmem.c
+++ b/drivers/cxl/pmem.c
@@ -58,6 +58,63 @@ static const struct attribute_group *cxl_dimm_attribute_groups[] = {
 	NULL
 };
 
+static int match_ep_decoder(struct device *dev, void *data)
+{
+	struct cxl_decoder *cxld = to_cxl_decoder(dev);
+
+	if (!cxld->region)
+		return 1;
+	else
+		return 0;
+}
+
+static struct cxl_decoder *cxl_find_free_decoder(struct cxl_port *port)
+{
+	struct device *dev;
+
+	dev = device_find_child(&port->dev, NULL, match_ep_decoder);
+	if (!dev)
+		return NULL;
+
+	return to_cxl_decoder(dev);
+}
+
+static int create_pmem_region(struct nvdimm *nvdimm)
+{
+	struct cxl_nvdimm *cxl_nvd;
+	struct cxl_memdev *cxlmd;
+	struct cxl_nvdimm_bridge *cxl_nvb;
+	struct cxl_pmem_region_params *params;
+	struct cxl_root_decoder *cxlrd;
+	struct cxl_decoder *cxld;
+	struct cxl_region *cxlr;
+
+	if (!nvdimm)
+		return -ENOTTY;
+
+	if (!nvdimm_has_cxl_region(nvdimm))
+		return 0;
+
+	cxl_nvd = nvdimm_provider_data(nvdimm);
+	params = nvdimm_get_cxl_region_param(nvdimm);
+	cxlmd = cxl_nvd->cxlmd;
+	cxl_nvb = cxlmd->cxl_nvb;
+	cxlrd = cxlmd->cxlrd;
+
+	/* FIXME: Limitation: Region creation only when interleave way == 1 */
+	if (params->nlabel == 1) {
+		cxld = cxl_find_free_decoder(cxlmd->endpoint);
+		cxlr = cxl_create_pmem_region(cxlrd, cxld, params,
+				atomic_read(&cxlrd->region_id));
+		if (IS_ERR(cxlr))
+			dev_dbg(&cxlmd->dev, "Region Creation failed\n");
+	} else {
+		dev_dbg(&cxlmd->dev, "Region Creation is not supported with iw > 1\n");
+	}
+
+	return 0;
+}
+
 static int cxl_nvdimm_probe(struct device *dev)
 {
 	struct cxl_nvdimm *cxl_nvd = to_cxl_nvdimm(dev);
@@ -74,6 +131,7 @@ static int cxl_nvdimm_probe(struct device *dev)
 		return rc;
 
 	set_bit(NDD_LABELING, &flags);
+	set_bit(NDD_CXL_LABEL, &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);
@@ -86,6 +144,7 @@ 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