linux-kernel - [PATCH RFC V2 1/3] of: dynamic: Add of_create_node() and of_destroy

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Date:   Wed, 12 Oct 2022 11:13:58 -0700
From:   Lizhi Hou <lizhi.hou@....com>
To:     <linux-pci@...r.kernel.org>, <devicetree@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>, <robh@...nel.org>,
        <frowand.list@...il.com>, <helgaas@...nel.org>
CC:     Lizhi Hou <lizhi.hou@....com>, <clement.leger@...tlin.com>,
        <max.zhen@....com>, <sonal.santan@....com>, <larry.liu@....com>,
        <brian.xu@....com>, <stefano.stabellini@...inx.com>,
        <trix@...hat.com>
Subject: [PATCH RFC V2 1/3] of: dynamic: Add of_create_node() and of_destroy_node()

of_create_node() creates device node and apply to base tree dynamically.
The parent device node and full name are required for creating the node.
And the caller can also provide a property array for the node.

Inside this function, it creates a changeset. Then the new device node
and properties are added to the changeset and applied to base tree. The
pointer of this changeset is saved in device node private data.

of_destroy_node() removes the node created by of_create_node() from the
base tree and free it. It gets the changeset pointer from device node
private data and call of_changeset_destroy() to free everything.

Signed-off-by: Lizhi Hou <lizhi.hou@....com>
Signed-off-by: Sonal Santan <sonal.santan@....com>
Signed-off-by: Max Zhen <max.zhen@....com>
Signed-off-by: Brian Xu <brian.xu@....com>
---
 drivers/of/dynamic.c | 80 ++++++++++++++++++++++++++++++++++++++++++++
 include/linux/of.h   |  4 +++
 2 files changed, 84 insertions(+)

diff --git a/drivers/of/dynamic.c b/drivers/of/dynamic.c
index cd3821a6444f..eca28b723706 100644
--- a/drivers/of/dynamic.c
+++ b/drivers/of/dynamic.c
@@ -934,3 +934,83 @@ int of_changeset_action(struct of_changeset *ocs, unsigned long action,
 	return 0;
 }
 EXPORT_SYMBOL_GPL(of_changeset_action);
+
+/**
+ * of_create_node - Dynamically create a device node and apply it to base tree
+ *
+ * @parent: Pointer to parent device node
+ * @full_name: Full name of device node
+ * @props: Pointer to property array
+ *
+ * Return: Pointer to the created device node or NULL in case of an error.
+ */
+struct device_node *of_create_node(struct device_node *parent,
+				   const char *full_name,
+				   struct property *props)
+{
+	struct of_changeset *cset;
+	struct property *new_pp;
+	struct device_node *np;
+	int ret, i;
+
+	cset = kzalloc(sizeof(*cset), GFP_KERNEL);
+	if (!cset)
+		return NULL;
+
+	of_changeset_init(cset);
+
+	np = __of_node_dup(NULL, full_name);
+	if (!np)
+		goto failed;
+	np->parent = parent;
+
+	ret = of_changeset_attach_node(cset, np);
+	if (ret)
+		goto failed;
+
+	if (props) {
+		for (i = 0; props[i].name; i++) {
+			new_pp = __of_prop_dup(&props[i], GFP_KERNEL);
+			if (!new_pp)
+				goto failed;
+			ret = of_changeset_add_property(cset, np, new_pp);
+			if (ret) {
+				kfree(new_pp->name);
+				kfree(new_pp->value);
+				kfree(new_pp);
+				goto failed;
+			}
+		}
+	}
+
+	ret = of_changeset_apply(cset);
+	if (ret)
+		goto failed;
+
+	np->data = cset;
+
+	return np;
+
+failed:
+	of_changeset_destroy(cset);
+	if (np)
+		of_node_put(np);
+
+	return NULL;
+}
+
+/**
+ * of_destroy_node - Destroy a dynamically created device node
+ *
+ * @np: Pointer to dynamically created device node
+ *
+ */
+void of_destroy_node(struct device_node *np)
+{
+	struct of_changeset *cset;
+
+	cset = (struct of_changeset *)np->data;
+	of_changeset_destroy(cset);
+	of_node_put(np);
+	kfree(cset);
+}
diff --git a/include/linux/of.h b/include/linux/of.h
index 766d002bddb9..493ef957c1a8 100644
--- a/include/linux/of.h
+++ b/include/linux/of.h
@@ -1475,6 +1475,10 @@ extern int of_changeset_revert(struct of_changeset *ocs);
 extern int of_changeset_action(struct of_changeset *ocs,
 		unsigned long action, struct device_node *np,
 		struct property *prop);
+struct device_node *of_create_node(struct device_node *parent,
+				   const char *full_name,
+				   struct property *props);
+void of_destroy_node(struct device_node *np);
 
 static inline int of_changeset_attach_node(struct of_changeset *ocs,
 		struct device_node *np)
-- 
2.17.1