cxl/memdev: Formalize endpoint port linkage

Move the endpoint port that the cxl_mem driver establishes from drvdata
to a first class attribute. This is in preparation for device-memory
drivers reusing the CXL core for memory region management. Those drivers
need a type-safe method to retrieve their CXL port linkage. Leave
drvdata for private usage of the cxl_mem driver not external consumers
of a 'struct cxl_memdev' object.

Reviewed-by: Fan Ni <fan.ni@samsung.com>
Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Reviewed-by: Dave Jiang <dave.jiang@intel.com>
Link: https://lore.kernel.org/r/168679264292.3436160.3901392135863405807.stgit@dwillia2-xfh.jf.intel.com
Signed-off-by: Dan Williams <dan.j.williams@intel.com>

Author: djbw

drivers/cxl/core/memdev.c

@@ -149,7 +149,7 @@ int cxl_trigger_poison_list(struct cxl_memdev *cxlmd)
 	struct cxl_port *port;
 	int rc;
 
-	port = dev_get_drvdata(&cxlmd->dev);
+	port = cxlmd->endpoint;
 	if (!port || !is_cxl_endpoint(port))
 		return -EINVAL;
 
@@ -207,7 +207,7 @@ static struct cxl_region *cxl_dpa_to_region(struct cxl_memdev *cxlmd, u64 dpa)
 	ctx = (struct cxl_dpa_to_region_context) {
 		.dpa = dpa,
 	};
-	port = dev_get_drvdata(&cxlmd->dev);
+	port = cxlmd->endpoint;
 	if (port && is_cxl_endpoint(port) && port->commit_end != -1)
 		device_for_each_child(&port->dev, &ctx, __cxl_dpa_to_region);
 

drivers/cxl/core/pmem.c

@@ -64,7 +64,7 @@ static int match_nvdimm_bridge(struct device *dev, void *data)
 
 struct cxl_nvdimm_bridge *cxl_find_nvdimm_bridge(struct cxl_memdev *cxlmd)
 {
-	struct cxl_port *port = find_cxl_root(dev_get_drvdata(&cxlmd->dev));
+	struct cxl_port *port = find_cxl_root(cxlmd->endpoint);
 	struct device *dev;
 
 	if (!port)

drivers/cxl/core/port.c

@@ -1161,7 +1161,7 @@ static struct device *grandparent(struct device *dev)
 static void delete_endpoint(void *data)
 {
 	struct cxl_memdev *cxlmd = data;
-	struct cxl_port *endpoint = dev_get_drvdata(&cxlmd->dev);
+	struct cxl_port *endpoint = cxlmd->endpoint;
 	struct cxl_port *parent_port;
 	struct device *parent;
 
@@ -1176,6 +1176,7 @@ static void delete_endpoint(void *data)
 		devm_release_action(parent, cxl_unlink_uport, endpoint);
 		devm_release_action(parent, unregister_port, endpoint);
 	}
+	cxlmd->endpoint = NULL;
 	device_unlock(parent);
 	put_device(parent);
 out:
@@ -1187,7 +1188,7 @@ int cxl_endpoint_autoremove(struct cxl_memdev *cxlmd, struct cxl_port *endpoint)
 	struct device *dev = &cxlmd->dev;
 
 	get_device(&endpoint->dev);
-	dev_set_drvdata(dev, endpoint);
+	cxlmd->endpoint = endpoint;
 	cxlmd->depth = endpoint->depth;
 	return devm_add_action_or_reset(dev, delete_endpoint, cxlmd);
 }

drivers/cxl/cxlmem.h

@@ -38,6 +38,7 @@
  * @detach_work: active memdev lost a port in its ancestry
  * @cxl_nvb: coordinate removal of @cxl_nvd if present
  * @cxl_nvd: optional bridge to an nvdimm if the device supports pmem
+ * @endpoint: connection to the CXL port topology for this memory device
  * @id: id number of this memdev instance.
  * @depth: endpoint port depth
  */
@@ -48,6 +49,7 @@ struct cxl_memdev {
 	struct work_struct detach_work;
 	struct cxl_nvdimm_bridge *cxl_nvb;
 	struct cxl_nvdimm *cxl_nvd;
+	struct cxl_port *endpoint;
 	int id;
 	int depth;
 };