software node: Introduce device_add_software_node()

This helper will register a software node and then assign
it to device at the same time. The function will also make
sure that the device can't have more than one software node.
Acked-by: Felipe Balbi <balbi@kernel.org>
Signed-off-by: Heikki Krogerus <heikki.krogerus@linux.intel.com>
Link: https://lore.kernel.org/r/20210115094914.88401-2-heikki.krogerus@linux.intel.comSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/base/swnode.c

@@ -48,6 +48,19 @@ EXPORT_SYMBOL_GPL(is_software_node);
 				     struct swnode, fwnode) : NULL;	\
 	})
 
+static inline struct swnode *dev_to_swnode(struct device *dev)
+{
+	struct fwnode_handle *fwnode = dev_fwnode(dev);
+
+	if (!fwnode)
+		return NULL;
+
+	if (!is_software_node(fwnode))
+		fwnode = fwnode->secondary;
+
+	return to_swnode(fwnode);
+}
+
 static struct swnode *
 software_node_to_swnode(const struct software_node *node)
 {
@@ -843,22 +856,62 @@ void fwnode_remove_software_node(struct fwnode_handle *fwnode)
 }
 EXPORT_SYMBOL_GPL(fwnode_remove_software_node);
 
+/**
+ * device_add_software_node - Assign software node to a device
+ * @dev: The device the software node is meant for.
+ * @swnode: The software node.
+ *
+ * This function will register @swnode and make it the secondary firmware node
+ * pointer of @dev. If @dev has no primary node, then @swnode will become the primary
+ * node.
+ */
+int device_add_software_node(struct device *dev, const struct software_node *swnode)
+{
+	int ret;
+
+	/* Only one software node per device. */
+	if (dev_to_swnode(dev))
+		return -EBUSY;
+
+	ret = software_node_register(swnode);
+	if (ret)
+		return ret;
+
+	set_secondary_fwnode(dev, software_node_fwnode(swnode));
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(device_add_software_node);
+
+/**
+ * device_remove_software_node - Remove device's software node
+ * @dev: The device with the software node.
+ *
+ * This function will unregister the software node of @dev.
+ */
+void device_remove_software_node(struct device *dev)
+{
+	struct swnode *swnode;
+
+	swnode = dev_to_swnode(dev);
+	if (!swnode)
+		return;
+
+	software_node_notify(dev, KOBJ_REMOVE);
+	set_secondary_fwnode(dev, NULL);
+	kobject_put(&swnode->kobj);
+}
+EXPORT_SYMBOL_GPL(device_remove_software_node);
+
 int software_node_notify(struct device *dev, unsigned long action)
 {
-	struct fwnode_handle *fwnode = dev_fwnode(dev);
 	struct swnode *swnode;
 	int ret;
 
-	if (!fwnode)
-		return 0;
-
-	if (!is_software_node(fwnode))
-		fwnode = fwnode->secondary;
-	if (!is_software_node(fwnode))
+	swnode = dev_to_swnode(dev);
+	if (!swnode)
 		return 0;
 
-	swnode = to_swnode(fwnode);
-
 	switch (action) {
 	case KOBJ_ADD:
 		ret = sysfs_create_link(&dev->kobj, &swnode->kobj,

include/linux/property.h

@@ -488,4 +488,7 @@ fwnode_create_software_node(const struct property_entry *properties,
 			    const struct fwnode_handle *parent);
 void fwnode_remove_software_node(struct fwnode_handle *fwnode);
 
+int device_add_software_node(struct device *dev, const struct software_node *swnode);
+void device_remove_software_node(struct device *dev);
+
 #endif /* _LINUX_PROPERTY_H_ */