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[96.255.20.138]) by smtp.gmail.com with ESMTPSA id af79cd13be357-8c71b859eaesm282041685a.46.2026.01.29.13.05.02 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 29 Jan 2026 13:05:03 -0800 (PST) From: Gregory Price To: linux-mm@kvack.org Cc: linux-cxl@vger.kernel.org, nvdimm@lists.linux.dev, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, linux-doc@vger.kernel.org, kernel-team@meta.com, dave@stgolabs.net, jonathan.cameron@huawei.com, dave.jiang@intel.com, alison.schofield@intel.com, vishal.l.verma@intel.com, ira.weiny@intel.com, dan.j.williams@intel.com, willy@infradead.org, jack@suse.cz, terry.bowman@amd.com, john@jagalactic.com Subject: [PATCH 7/9] cxl/core: add cxl_devdax_region driver for explicit userland region binding Date: Thu, 29 Jan 2026 16:04:40 -0500 Message-ID: <20260129210442.3951412-8-gourry@gourry.net> X-Mailer: git-send-email 2.52.0 In-Reply-To: <20260129210442.3951412-1-gourry@gourry.net> References: <20260129210442.3951412-1-gourry@gourry.net> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" Add a new cxl_devdax_region driver that probes CXL regions in device dax mode and creates dax_region devices. This allows explicit binding to the device_dax dax driver instead of the kmem driver. Exports to_cxl_region() to core.h so it can be used by the driver. Signed-off-by: Gregory Price --- drivers/cxl/core/core.h | 2 ++ drivers/cxl/core/dax_region.c | 16 ++++++++++++++++ drivers/cxl/core/region.c | 21 +++++++++++++++++---- drivers/cxl/cxl.h | 1 + 4 files changed, 36 insertions(+), 4 deletions(-) diff --git a/drivers/cxl/core/core.h b/drivers/cxl/core/core.h index 217dd708a2a6..ea4df8abc2ad 100644 --- a/drivers/cxl/core/core.h +++ b/drivers/cxl/core/core.h @@ -46,6 +46,8 @@ u64 cxl_dpa_to_hpa(struct cxl_region *cxlr, const struct = cxl_memdev *cxlmd, int devm_cxl_add_dax_region(struct cxl_region *cxlr, enum dax_driver_type); int devm_cxl_add_pmem_region(struct cxl_region *cxlr); =20 +extern struct cxl_driver cxl_devdax_region_driver; + #else static inline u64 cxl_dpa_to_hpa(struct cxl_region *cxlr, const struct cxl_memdev *cxlmd, u64 dpa) diff --git a/drivers/cxl/core/dax_region.c b/drivers/cxl/core/dax_region.c index 0602db5f7248..391d51e5ec37 100644 --- a/drivers/cxl/core/dax_region.c +++ b/drivers/cxl/core/dax_region.c @@ -111,3 +111,19 @@ int devm_cxl_add_dax_region(struct cxl_region *cxlr, put_device(dev); return rc; } + +static int cxl_devdax_region_driver_probe(struct device *dev) +{ + struct cxl_region *cxlr =3D to_cxl_region(dev); + + if (cxlr->mode !=3D CXL_PARTMODE_RAM) + return -ENODEV; + + return devm_cxl_add_dax_region(cxlr, DAXDRV_DEVICE_TYPE); +} + +struct cxl_driver cxl_devdax_region_driver =3D { + .name =3D "cxl_devdax_region", + .probe =3D cxl_devdax_region_driver_probe, + .id =3D CXL_DEVICE_REGION, +}; diff --git a/drivers/cxl/core/region.c b/drivers/cxl/core/region.c index 61ec939c1462..6200ca1cc2dd 100644 --- a/drivers/cxl/core/region.c +++ b/drivers/cxl/core/region.c @@ -39,8 +39,6 @@ */ static nodemask_t nodemask_region_seen =3D NODE_MASK_NONE; =20 -static struct cxl_region *to_cxl_region(struct device *dev); - #define __ACCESS_ATTR_RO(_level, _name) { \ .attr =3D { .name =3D __stringify(_name), .mode =3D 0444 }, \ .show =3D _name##_access##_level##_show, \ @@ -2430,7 +2428,7 @@ bool is_cxl_region(struct device *dev) } EXPORT_SYMBOL_NS_GPL(is_cxl_region, "CXL"); =20 -static struct cxl_region *to_cxl_region(struct device *dev) +struct cxl_region *to_cxl_region(struct device *dev) { if (dev_WARN_ONCE(dev, dev->type !=3D &cxl_region_type, "not a cxl_region device\n")) @@ -3726,11 +3724,26 @@ static struct cxl_driver cxl_region_driver =3D { =20 int cxl_region_init(void) { - return cxl_driver_register(&cxl_region_driver); + int rc; + + rc =3D cxl_driver_register(&cxl_region_driver); + if (rc) + return rc; + + rc =3D cxl_driver_register(&cxl_devdax_region_driver); + if (rc) + goto err_dax; + + return 0; + +err_dax: + cxl_driver_unregister(&cxl_region_driver); + return rc; } =20 void cxl_region_exit(void) { + cxl_driver_unregister(&cxl_devdax_region_driver); cxl_driver_unregister(&cxl_region_driver); } =20 diff --git a/drivers/cxl/cxl.h b/drivers/cxl/cxl.h index c06a239c0008..674d5f870c70 100644 --- a/drivers/cxl/cxl.h +++ b/drivers/cxl/cxl.h @@ -859,6 +859,7 @@ int cxl_dvsec_rr_decode(struct cxl_dev_state *cxlds, struct cxl_endpoint_dvsec_info *info); =20 bool is_cxl_region(struct device *dev); +struct cxl_region *to_cxl_region(struct device *dev); =20 extern const struct bus_type cxl_bus_type; =20 --=20 2.52.0