driver core: platform: remove software node on release()

If we pass a software node to a newly created device using struct
platform_device_info, it will not be removed when the device is
released. This may happen when a module creating the device is removed
or on failure in platform_device_add().

When we try to reuse that software node in a subsequent call to
platform_device_register_full(), it will fail with -EBUSY.

Provide a wrapper around the existing platform_device_release() that
additionally calls device_remove_software_node() and use it to replace
the former if we end up adding a software node.

While at it: check all three possible situations in which two software
nodes for a single platform device can be created/assigned in
platform_device_register_full() and bail-out early.

Fixes: 0fc434b ("driver core: platform: allow attaching software nodes when creating devices")
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@oss.qualcomm.com>
Link: https://patch.msgid.link/20260513-swnode-remove-on-dev-unreg-v6-1-f9c58939df27@oss.qualcomm.com
Signed-off-by: Danilo Krummrich <dakr@kernel.org>

Author: brgl

drivers/base/platform.c

@@ -606,6 +606,12 @@ static void platform_device_release(struct device *dev)
 	kfree(pa);
 }
 
+static void platform_device_release_full(struct device *dev)
+{
+	device_remove_software_node(dev);
+	platform_device_release(dev);
+}
+
 /**
  * platform_device_alloc - create a platform device
  * @name: base name of the device we're adding
@@ -848,7 +854,13 @@ struct platform_device *platform_device_register_full(const struct platform_devi
 	int ret;
 	struct platform_device *pdev;
 
-	if (pdevinfo->swnode && pdevinfo->properties)
+	/*
+	 * Only one software node per device is allowed. Make sure we don't
+	 * accept or create two.
+	 */
+	if ((pdevinfo->swnode && pdevinfo->properties) ||
+	    (pdevinfo->swnode && is_software_node(pdevinfo->fwnode)) ||
+	    (pdevinfo->properties && is_software_node(pdevinfo->fwnode)))
 		return ERR_PTR(-EINVAL);
 
 	pdev = platform_device_alloc(pdevinfo->name, pdevinfo->id);
@@ -878,6 +890,8 @@ struct platform_device *platform_device_register_full(const struct platform_devi
 		ret = device_add_software_node(&pdev->dev, pdevinfo->swnode);
 		if (ret)
 			goto err;
+
+		pdev->dev.release = platform_device_release_full;
 	} else if (pdevinfo->properties) {
 		ret = device_create_managed_software_node(&pdev->dev,
 							  pdevinfo->properties, NULL);