of: device_node kobject lifecycle fixes

After the move to having device nodes be proper kobjects the lifecycle
of the node needs to be controlled better.

At first convert of_add_node() in the unflattened functions to
of_init_node() which initializes the kobject so that of_node_get/put
work correctly even before of_init is called.

Afterwards introduce of_node_is_initialized & of_node_is_attached that
query the underlying kobject about the state (attached means kobj
is visible in sysfs)

Using that make sure the lifecycle of the tree is correct at all
times.

Signed-off-by: Pantelis Antoniou <panto@antoniou-consulting.com>
[grant.likely: moved of_node_init() calls, fixed up locking, and
               dropped __of_populate() hunks]
Signed-off-by: Grant Likely <grant.likely@linaro.org>

1 files changed, 19 insertions, 0 deletions

diff --git a/include/linux/of.h b/include/linux/of.h
index 257994a420f3..a8b9dad90c64 100644
--- a/include/linux/of.h
+++ b/include/linux/of.h
@@ -76,6 +76,25 @@ struct of_phandle_args {
 
 extern int of_node_add(struct device_node *node);
 
+/* initialize a node */
+extern struct kobj_type of_node_ktype;
+static inline void of_node_init(struct device_node *node)
+{
+        kobject_init(&node->kobj, &of_node_ktype);
+}
+
+/* true when node is initialized */
+static inline int of_node_is_initialized(struct device_node *node)
+{
+        return node && node->kobj.state_initialized;
+}
+
+/* true when node is attached (i.e. present on sysfs) */
+static inline int of_node_is_attached(struct device_node *node)
+{
+        return node && node->kobj.state_in_sysfs;
+}
+
 #ifdef CONFIG_OF_DYNAMIC
 extern struct device_node *of_node_get(struct device_node *node);
 extern void of_node_put(struct device_node *node);