[PATCH 6/9] cxl/core/region: move dax region device logic into dax_region.c

Gregory Price
2026-01-29T21:05:02Z

Move the CXL DAX region device infrastructure from region.c into a
new dax_region.c file.

No functional changes.

Signed-off-by: Gregory Price <gourry@gourry.net>
---
drivers/cxl/core/Makefile | 1 +
drivers/cxl/core/core.h | 1 +
drivers/cxl/core/dax_region.c | 113 ++++++++++++++++++++++++++++++++++
drivers/cxl/core/region.c | 102 ------------------------------
4 files changed, 115 insertions(+), 102 deletions(-)
create mode 100644 drivers/cxl/core/dax_region.c

diff --git a/drivers/cxl/core/Makefile b/drivers/cxl/core/Makefile
index 23269c81fd44..36f284d7c500 100644
--- a/drivers/cxl/core/Makefile
+++ b/drivers/cxl/core/Makefile
@@ -17,6 +17,7 @@ cxl_core-y += cdat.o
cxl_core-y += ras.o
cxl_core-$(CONFIG_TRACING) += trace.o
cxl_core-$(CONFIG_CXL_REGION) += region.o
+cxl_core-$(CONFIG_CXL_REGION) += dax_region.o
cxl_core-$(CONFIG_CXL_REGION) += pmem_region.o
cxl_core-$(CONFIG_CXL_MCE) += mce.o
cxl_core-$(CONFIG_CXL_FEATURES) += features.o
diff --git a/drivers/cxl/core/core.h b/drivers/cxl/core/core.h
index 26991de12d76..217dd708a2a6 100644
--- a/drivers/cxl/core/core.h
+++ b/drivers/cxl/core/core.h
@@ -43,6 +43,7 @@ int cxl_get_poison_by_endpoint(struct cxl_port *port);
struct cxl_region *cxl_dpa_to_region(const struct cxl_memdev *cxlmd, u64 dpa);
u64 cxl_dpa_to_hpa(struct cxl_region *cxlr, const struct cxl_memdev *cxlmd,
u64 dpa);
+int devm_cxl_add_dax_region(struct cxl_region *cxlr, enum dax_driver_type);
int devm_cxl_add_pmem_region(struct cxl_region *cxlr);

#else
diff --git a/drivers/cxl/core/dax_region.c b/drivers/cxl/core/dax_region.c
new file mode 100644
index 000000000000..0602db5f7248
--- /dev/null
+++ b/drivers/cxl/core/dax_region.c
@@ -0,0 +1,113 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright(c) 2022 Intel Corporation. All rights reserved.
+ * Copyright(c) 2026 Meta Technologies Inc. All rights reserved.
+ */
+#include <linux/memory_hotplug.h>
+#include <linux/device.h>
+#include <linux/slab.h>
+#include <cxlmem.h>
+#include <cxl.h>
+#include "core.h"
+
+static void cxl_dax_region_release(struct device *dev)
+{
+ struct cxl_dax_region *cxlr_dax = to_cxl_dax_region(dev);
+
+ kfree(cxlr_dax);
+}
+
+static const struct attribute_group *cxl_dax_region_attribute_groups[] = {
+ &cxl_base_attribute_group,
+ NULL,
+};
+
+const struct device_type cxl_dax_region_type = {
+ .name = "cxl_dax_region",
+ .release = cxl_dax_region_release,
+ .groups = cxl_dax_region_attribute_groups,
+};
+
+static bool is_cxl_dax_region(struct device *dev)
+{
+ return dev->type == &cxl_dax_region_type;
+}
+
+struct cxl_dax_region *to_cxl_dax_region(struct device *dev)
+{
+ if (dev_WARN_ONCE(dev, !is_cxl_dax_region(dev),
+ "not a cxl_dax_region device\n"))
+ return NULL;
+ return container_of(dev, struct cxl_dax_region, dev);
+}
+EXPORT_SYMBOL_NS_GPL(to_cxl_dax_region, "CXL");
+
+static struct lock_class_key cxl_dax_region_key;
+
+static struct cxl_dax_region *cxl_dax_region_alloc(struct cxl_region *cxlr)
+{
+ struct cxl_region_params *p = &cxlr->params;
+ struct cxl_dax_region *cxlr_dax;
+ struct device *dev;
+
+ guard(rwsem_read)(&cxl_rwsem.region);
+ if (p->state != CXL_CONFIG_COMMIT)
+ return ERR_PTR(-ENXIO);
+
+ cxlr_dax = kzalloc(sizeof(*cxlr_dax), GFP_KERNEL);
+ if (!cxlr_dax)
+ return ERR_PTR(-ENOMEM);
+
+ cxlr_dax->hpa_range.start = p->res->start;
+ cxlr_dax->hpa_range.end = p->res->end;
+
+ dev = &cxlr_dax->dev;
+ cxlr_dax->cxlr = cxlr;
+ device_initialize(dev);
+ lockdep_set_class(&dev->mutex, &cxl_dax_region_key);
+ device_set_pm_not_required(dev);
+ dev->parent = &cxlr->dev;
+ dev->bus = &cxl_bus_type;
+ dev->type = &cxl_dax_region_type;
+
+ return cxlr_dax;
+}
+
+static void cxlr_dax_unregister(void *_cxlr_dax)
+{
+ struct cxl_dax_region *cxlr_dax = _cxlr_dax;
+
+ device_unregister(&cxlr_dax->dev);
+}
+
+int devm_cxl_add_dax_region(struct cxl_region *cxlr,
+ enum dax_driver_type dax_driver)
+{
+ struct cxl_dax_region *cxlr_dax;
+ struct device *dev;
+ int rc;
+
+ cxlr_dax = cxl_dax_region_alloc(cxlr);
+ if (IS_ERR(cxlr_dax))
+ return PTR_ERR(cxlr_dax);
+
+ cxlr_dax->online_type = mhp_get_default_online_type();
+ cxlr_dax->dax_driver = dax_driver;
+ dev = &cxlr_dax->dev;
+ rc = dev_set_name(dev, "dax_region%d", cxlr->id);
+ if (rc)
+ goto err;
+
+ rc = device_add(dev);
+ if (rc)
+ goto err;
+
+ dev_dbg(&cxlr->dev, "%s: register %s\n", dev_name(dev->parent),
+ dev_name(dev));
+
+ return devm_add_action_or_reset(&cxlr->dev, cxlr_dax_unregister,
+ cxlr_dax);
+err:
+ put_device(dev);
+ return rc;
+}
diff --git a/drivers/cxl/core/region.c b/drivers/cxl/core/region.c
index fc56f8f03805..61ec939c1462 100644
--- a/drivers/cxl/core/region.c
+++ b/drivers/cxl/core/region.c
@@ -3196,108 +3196,6 @@ static int region_offset_to_dpa_result(struct cxl_region *cxlr, u64 offset,
return -ENXIO;
}

-static void cxl_dax_region_release(struct device *dev)
-{
- struct cxl_dax_region *cxlr_dax = to_cxl_dax_region(dev);
-
- kfree(cxlr_dax);
-}
-
-static const struct attribute_group *cxl_dax_region_attribute_groups[] = {
- &cxl_base_attribute_group,
- NULL,
-};
-
-const struct device_type cxl_dax_region_type = {
- .name = "cxl_dax_region",
- .release = cxl_dax_region_release,
- .groups = cxl_dax_region_attribute_groups,
-};
-
-static bool is_cxl_dax_region(struct device *dev)
-{
- return dev->type == &cxl_dax_region_type;
-}
-
-struct cxl_dax_region *to_cxl_dax_region(struct device *dev)
-{
- if (dev_WARN_ONCE(dev, !is_cxl_dax_region(dev),
- "not a cxl_dax_region device\n"))
- return NULL;
- return container_of(dev, struct cxl_dax_region, dev);
-}
-EXPORT_SYMBOL_NS_GPL(to_cxl_dax_region, "CXL");
-
-static struct lock_class_key cxl_dax_region_key;
-
-static struct cxl_dax_region *cxl_dax_region_alloc(struct cxl_region *cxlr)
-{
- struct cxl_region_params *p = &cxlr->params;
- struct cxl_dax_region *cxlr_dax;
- struct device *dev;
-
- guard(rwsem_read)(&cxl_rwsem.region);
- if (p->state != CXL_CONFIG_COMMIT)
- return ERR_PTR(-ENXIO);
-
- cxlr_dax = kzalloc(sizeof(*cxlr_dax), GFP_KERNEL);
- if (!cxlr_dax)
- return ERR_PTR(-ENOMEM);
-
- cxlr_dax->hpa_range.start = p->res->start;
- cxlr_dax->hpa_range.end = p->res->end;
-
- dev = &cxlr_dax->dev;
- cxlr_dax->cxlr = cxlr;
- device_initialize(dev);
- lockdep_set_class(&dev->mutex, &cxl_dax_region_key);
- device_set_pm_not_required(dev);
- dev->parent = &cxlr->dev;
- dev->bus = &cxl_bus_type;
- dev->type = &cxl_dax_region_type;
-
- return cxlr_dax;
-}
-
-static void cxlr_dax_unregister(void *_cxlr_dax)
-{
- struct cxl_dax_region *cxlr_dax = _cxlr_dax;
-
- device_unregister(&cxlr_dax->dev);
-}
-
-static int devm_cxl_add_dax_region(struct cxl_region *cxlr,
- enum dax_driver_type dax_driver)
-{
- struct cxl_dax_region *cxlr_dax;
- struct device *dev;
- int rc;
-
- cxlr_dax = cxl_dax_region_alloc(cxlr);
- if (IS_ERR(cxlr_dax))
- return PTR_ERR(cxlr_dax);
-
- cxlr_dax->online_type = mhp_get_default_online_type();
- cxlr_dax->dax_driver = dax_driver;
- dev = &cxlr_dax->dev;
- rc = dev_set_name(dev, "dax_region%d", cxlr->id);
- if (rc)
- goto err;
-
- rc = device_add(dev);
- if (rc)
- goto err;
-
- dev_dbg(&cxlr->dev, "%s: register %s\n", dev_name(dev->parent),
- dev_name(dev));
-
- return devm_add_action_or_reset(&cxlr->dev, cxlr_dax_unregister,
- cxlr_dax);
-err:
- put_device(dev);
- return rc;
-}
-
static int match_decoder_by_range(struct device *dev, const void *data)
{
const struct range *r1, *r2 = data;
--
2.52.0