Re: [PATCH v2 3/3] cxl/core/region: move dax region driver logic into dax_region

[Davidlohr Bueso <dave@stgolabs.net>]

On Tue, 13 Jan 2026, Gregory Price wrote:

>Move the dax region driver logic from region.c into dax_region.c
>
>Signed-off-by: Gregory Price <gourry@gourry.net>

Acked-by: Davidlohr Bueso <dave@stgolabs.net>

>---
> drivers/cxl/core/Makefile     |   1 +
> drivers/cxl/core/core.h       |   1 +
> drivers/cxl/core/dax_region.c | 106 ++++++++++++++++++++++++++++++++++
> drivers/cxl/core/region.c     |  99 -------------------------------
> 4 files changed, 108 insertions(+), 99 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 cd589e81f55e..3ea850408814 100644
>--- a/drivers/cxl/core/core.h
>+++ b/drivers/cxl/core/core.h
>@@ -42,6 +42,7 @@ 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);
> 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..d7c38447f816
>--- /dev/null
>+++ b/drivers/cxl/core/dax_region.c
>@@ -0,0 +1,106 @@
>+// SPDX-License-Identifier: GPL-2.0-only
>+/* Copyright(c) 2022 Intel Corporation. All rights reserved. */
>+#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)
>+{
>+	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);
>+
>+	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 a61805542b56..1ca5f5b02b22 100644
>--- a/drivers/cxl/core/region.c
>+++ b/drivers/cxl/core/region.c
>@@ -3239,105 +3239,6 @@ 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)
>-{
>-	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);
>-
>-	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
>