cxl: Simplify cxl_root_ops allocation and handling

A root port's callback handlers are collected in struct cxl_root_ops.
The structure is dynamically allocated, though it contains only a
single pointer in it. This also requires to check two pointers to
check for the existance of a callback.

Simplify the allocation, release and handler check by embedding the
ops statically in struct cxl_root.

Reviewed-by: Dave Jiang <dave.jiang@intel.com>
Reviewed-by: Jonathan Cameron <jonathan.cameron@huawei.com>
Reviewed-by: Alison Schofield <alison.schofield@intel.com>
Signed-off-by: Robert Richter <rrichter@amd.com>
Link: https://patch.msgid.link/20260114164837.1076338-5-rrichter@amd.com
Signed-off-by: Dave Jiang <dave.jiang@intel.com>

Author: Robert Richter

drivers/cxl/acpi.c

@@ -318,10 +318,6 @@ static int cxl_acpi_qos_class(struct cxl_root *cxl_root,
 	return cxl_acpi_evaluate_qtg_dsm(handle, coord, entries, qos_class);
 }
 
-static const struct cxl_root_ops acpi_root_ops = {
-	.qos_class = cxl_acpi_qos_class,
-};
-
 static void del_cxl_resource(struct resource *res)
 {
 	if (!res)
@@ -923,9 +919,10 @@ static int cxl_acpi_probe(struct platform_device *pdev)
 	cxl_res->end = -1;
 	cxl_res->flags = IORESOURCE_MEM;
 
-	cxl_root = devm_cxl_add_root(host, &acpi_root_ops);
+	cxl_root = devm_cxl_add_root(host);
 	if (IS_ERR(cxl_root))
 		return PTR_ERR(cxl_root);
+	cxl_root->ops.qos_class = cxl_acpi_qos_class;
 	root_port = &cxl_root->port;
 
 	rc = bus_for_each_dev(adev->dev.bus, NULL, root_port,

drivers/cxl/core/cdat.c

@@ -213,17 +213,17 @@ static int cxl_port_perf_data_calculate(struct cxl_port *port,
 	if (!cxl_root)
 		return -ENODEV;
 
-	if (!cxl_root->ops || !cxl_root->ops->qos_class)
+	if (!cxl_root->ops.qos_class)
 		return -EOPNOTSUPP;
 
 	xa_for_each(dsmas_xa, index, dent) {
 		int qos_class;
 
 		cxl_coordinates_combine(dent->coord, dent->cdat_coord, ep_c);
 		dent->entries = 1;
-		rc = cxl_root->ops->qos_class(cxl_root,
-					      &dent->coord[ACCESS_COORDINATE_CPU],
-					      1, &qos_class);
+		rc = cxl_root->ops.qos_class(cxl_root,
+					     &dent->coord[ACCESS_COORDINATE_CPU],
+					     1, &qos_class);
 		if (rc != 1)
 			continue;
 

drivers/cxl/core/port.c

@@ -954,19 +954,15 @@ struct cxl_port *devm_cxl_add_port(struct device *host,
 }
 EXPORT_SYMBOL_NS_GPL(devm_cxl_add_port, "CXL");
 
-struct cxl_root *devm_cxl_add_root(struct device *host,
-				   const struct cxl_root_ops *ops)
+struct cxl_root *devm_cxl_add_root(struct device *host)
 {
-	struct cxl_root *cxl_root;
 	struct cxl_port *port;
 
 	port = devm_cxl_add_port(host, host, CXL_RESOURCE_NONE, NULL);
 	if (IS_ERR(port))
 		return ERR_CAST(port);
 
-	cxl_root = to_cxl_root(port);
-	cxl_root->ops = ops;
-	return cxl_root;
+	return to_cxl_root(port);
 }
 EXPORT_SYMBOL_NS_GPL(devm_cxl_add_root, "CXL");
 

drivers/cxl/cxl.h

@@ -646,6 +646,14 @@ struct cxl_port {
 	resource_size_t component_reg_phys;
 };
 
+struct cxl_root;
+
+struct cxl_root_ops {
+	int (*qos_class)(struct cxl_root *cxl_root,
+			 struct access_coordinate *coord, int entries,
+			 int *qos_class);
+};
+
 /**
  * struct cxl_root - logical collection of root cxl_port items
  *
@@ -654,7 +662,7 @@ struct cxl_port {
  */
 struct cxl_root {
 	struct cxl_port port;
-	const struct cxl_root_ops *ops;
+	struct cxl_root_ops ops;
 };
 
 static inline struct cxl_root *
@@ -663,12 +671,6 @@ to_cxl_root(const struct cxl_port *port)
 	return container_of(port, struct cxl_root, port);
 }
 
-struct cxl_root_ops {
-	int (*qos_class)(struct cxl_root *cxl_root,
-			 struct access_coordinate *coord, int entries,
-			 int *qos_class);
-};
-
 static inline struct cxl_dport *
 cxl_find_dport_by_dev(struct cxl_port *port, const struct device *dport_dev)
 {
@@ -782,8 +784,7 @@ struct cxl_port *devm_cxl_add_port(struct device *host,
 				   struct device *uport_dev,
 				   resource_size_t component_reg_phys,
 				   struct cxl_dport *parent_dport);
-struct cxl_root *devm_cxl_add_root(struct device *host,
-				   const struct cxl_root_ops *ops);
+struct cxl_root *devm_cxl_add_root(struct device *host);
 struct cxl_root *find_cxl_root(struct cxl_port *port);
 
 DEFINE_FREE(put_cxl_root, struct cxl_root *, if (_T) put_device(&_T->port.dev))