cxl/port: Record parent dport when adding ports

At the time that cxl_port instances are being created, cache the dport
from the parent port that points to this new child port. This will be
useful for region provisioning when walking the tree to calculate
decoder targets, and saves rewalking the dport list after the fact to
build this information.
Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Link: https://lore.kernel.org/r/20220624041950.559155-1-dan.j.williams@intel.comSigned-off-by: Dan Williams <dan.j.williams@intel.com>

drivers/cxl/acpi.c

@@ -211,8 +211,7 @@ static int add_host_bridge_uport(struct device *match, void *arg)
 	if (rc)
 		return rc;
 
-	port = devm_cxl_add_port(host, match, dport->component_reg_phys,
-				 root_port);
+	port = devm_cxl_add_port(host, match, dport->component_reg_phys, dport);
 	if (IS_ERR(port))
 		return PTR_ERR(port);
 	dev_dbg(host, "%s: add: %s\n", dev_name(match), dev_name(&port->dev));

drivers/cxl/core/port.c

@@ -526,7 +526,7 @@ static struct lock_class_key cxl_port_key;
 
 static struct cxl_port *cxl_port_alloc(struct device *uport,
 				       resource_size_t component_reg_phys,
-				       struct cxl_port *parent_port)
+				       struct cxl_dport *parent_dport)
 {
 	struct cxl_port *port;
 	struct device *dev;
@@ -549,11 +549,13 @@ static struct cxl_port *cxl_port_alloc(struct device *uport,
 	 * description.
 	 */
 	dev = &port->dev;
-	if (parent_port) {
+	if (parent_dport) {
+		struct cxl_port *parent_port = parent_dport->port;
 		struct cxl_port *iter;
 
 		dev->parent = &parent_port->dev;
 		port->depth = parent_port->depth + 1;
+		port->parent_dport = parent_dport;
 
 		/*
 		 * walk to the host bridge, or the first ancestor that knows
@@ -595,24 +597,24 @@ static struct cxl_port *cxl_port_alloc(struct device *uport,
  * @host: host device for devm operations
  * @uport: "physical" device implementing this upstream port
  * @component_reg_phys: (optional) for configurable cxl_port instances
- * @parent_port: next hop up in the CXL memory decode hierarchy
+ * @parent_dport: next hop up in the CXL memory decode hierarchy
  */
 struct cxl_port *devm_cxl_add_port(struct device *host, struct device *uport,
 				   resource_size_t component_reg_phys,
-				   struct cxl_port *parent_port)
+				   struct cxl_dport *parent_dport)
 {
 	struct cxl_port *port;
 	struct device *dev;
 	int rc;
 
-	port = cxl_port_alloc(uport, component_reg_phys, parent_port);
+	port = cxl_port_alloc(uport, component_reg_phys, parent_dport);
 	if (IS_ERR(port))
 		return port;
 
 	dev = &port->dev;
 	if (is_cxl_memdev(uport))
 		rc = dev_set_name(dev, "endpoint%d", port->id);
-	else if (parent_port)
+	else if (parent_dport)
 		rc = dev_set_name(dev, "port%d", port->id);
 	else
 		rc = dev_set_name(dev, "root%d", port->id);
@@ -1014,7 +1016,7 @@ static void delete_endpoint(void *data)
 	struct cxl_port *parent_port;
 	struct device *parent;
 
-	parent_port = cxl_mem_find_port(cxlmd);
+	parent_port = cxl_mem_find_port(cxlmd, NULL);
 	if (!parent_port)
 		goto out;
 	parent = &parent_port->dev;
@@ -1149,8 +1151,8 @@ static int add_port_attach_ep(struct cxl_memdev *cxlmd,
 {
 	struct device *dparent = grandparent(dport_dev);
 	struct cxl_port *port, *parent_port = NULL;
+	struct cxl_dport *dport, *parent_dport;
 	resource_size_t component_reg_phys;
-	struct cxl_dport *dport;
 	int rc;
 
 	if (!dparent) {
@@ -1164,7 +1166,7 @@ static int add_port_attach_ep(struct cxl_memdev *cxlmd,
 		return -ENXIO;
 	}
 
-	parent_port = find_cxl_port(dparent, NULL);
+	parent_port = find_cxl_port(dparent, &parent_dport);
 	if (!parent_port) {
 		/* iterate to create this parent_port */
 		return -EAGAIN;
@@ -1183,7 +1185,7 @@ static int add_port_attach_ep(struct cxl_memdev *cxlmd,
 	if (!port) {
 		component_reg_phys = find_component_registers(uport_dev);
 		port = devm_cxl_add_port(&parent_port->dev, uport_dev,
-					 component_reg_phys, parent_port);
+					 component_reg_phys, parent_dport);
 		/* retry find to pick up the new dport information */
 		if (!IS_ERR(port))
 			port = find_cxl_port_at(parent_port, dport_dev, &dport);
@@ -1290,9 +1292,10 @@ int devm_cxl_enumerate_ports(struct cxl_memdev *cxlmd)
 }
 EXPORT_SYMBOL_NS_GPL(devm_cxl_enumerate_ports, CXL);
 
-struct cxl_port *cxl_mem_find_port(struct cxl_memdev *cxlmd)
+struct cxl_port *cxl_mem_find_port(struct cxl_memdev *cxlmd,
+				   struct cxl_dport **dport)
 {
-	return find_cxl_port(grandparent(&cxlmd->dev), NULL);
+	return find_cxl_port(grandparent(&cxlmd->dev), dport);
 }
 EXPORT_SYMBOL_NS_GPL(cxl_mem_find_port, CXL);
 

drivers/cxl/cxl.h

@@ -332,6 +332,7 @@ struct cxl_nvdimm {
  * @id: id for port device-name
  * @dports: cxl_dport instances referenced by decoders
  * @endpoints: cxl_ep instances, endpoints that are a descendant of this port
+ * @parent_dport: dport that points to this port in the parent
  * @decoder_ida: allocator for decoder ids
  * @hdm_end: track last allocated HDM decoder instance for allocation ordering
  * @component_reg_phys: component register capability base address (optional)
@@ -347,6 +348,7 @@ struct cxl_port {
 	int id;
 	struct list_head dports;
 	struct list_head endpoints;
+	struct cxl_dport *parent_dport;
 	struct ida decoder_ida;
 	int hdm_end;
 	resource_size_t component_reg_phys;
@@ -406,11 +408,12 @@ int devm_cxl_register_pci_bus(struct device *host, struct device *uport,
 struct pci_bus *cxl_port_to_pci_bus(struct cxl_port *port);
 struct cxl_port *devm_cxl_add_port(struct device *host, struct device *uport,
 				   resource_size_t component_reg_phys,
-				   struct cxl_port *parent_port);
+				   struct cxl_dport *parent_dport);
 struct cxl_port *find_cxl_root(struct device *dev);
 int devm_cxl_enumerate_ports(struct cxl_memdev *cxlmd);
 int cxl_bus_rescan(void);
-struct cxl_port *cxl_mem_find_port(struct cxl_memdev *cxlmd);
+struct cxl_port *cxl_mem_find_port(struct cxl_memdev *cxlmd,
+				   struct cxl_dport **dport);
 bool schedule_cxl_memdev_detach(struct cxl_memdev *cxlmd);
 
 struct cxl_dport *devm_cxl_add_dport(struct cxl_port *port,

drivers/cxl/mem.c

@@ -26,14 +26,15 @@
  */
 
 static int create_endpoint(struct cxl_memdev *cxlmd,
-			   struct cxl_port *parent_port)
+			   struct cxl_dport *parent_dport)
 {
+	struct cxl_port *parent_port = parent_dport->port;
 	struct cxl_dev_state *cxlds = cxlmd->cxlds;
 	struct cxl_port *endpoint;
 	int rc;
 
 	endpoint = devm_cxl_add_port(&parent_port->dev, &cxlmd->dev,
-				     cxlds->component_reg_phys, parent_port);
+				     cxlds->component_reg_phys, parent_dport);
 	if (IS_ERR(endpoint))
 		return PTR_ERR(endpoint);
 
@@ -76,6 +77,7 @@ static int cxl_mem_probe(struct device *dev)
 {
 	struct cxl_memdev *cxlmd = to_cxl_memdev(dev);
 	struct cxl_port *parent_port;
+	struct cxl_dport *dport;
 	struct dentry *dentry;
 	int rc;
 
@@ -100,7 +102,7 @@ static int cxl_mem_probe(struct device *dev)
 	if (rc)
 		return rc;
 
-	parent_port = cxl_mem_find_port(cxlmd);
+	parent_port = cxl_mem_find_port(cxlmd, &dport);
 	if (!parent_port) {
 		dev_err(dev, "CXL port topology not found\n");
 		return -ENXIO;
@@ -114,7 +116,7 @@ static int cxl_mem_probe(struct device *dev)
 		goto unlock;
 	}
 
-	rc = create_endpoint(cxlmd, parent_port);
+	rc = create_endpoint(cxlmd, dport);
 unlock:
 	device_unlock(&parent_port->dev);
 	put_device(&parent_port->dev);