[XEN][PATCH v7 08/19] xen/device-tree: Add device_tree_find_node_by_path() to find nodes in device tree

[Vikram Garhwal]

Add device_tree_find_node_by_path() to find a matching node with path for a
dt_device_node.

Reason behind this function:
    Each time overlay nodes are added using .dtbo, a new fdt(memcpy of
    device_tree_flattened) is created and updated with overlay nodes. This
    updated fdt is further unflattened to a dt_host_new. Next, we need to find
    the overlay nodes in dt_host_new, find the overlay node's parent in dt_host
    and add the nodes as child under their parent in the dt_host. Thus we need
    this function to search for node in different unflattened device trees.

Also, make dt_find_node_by_path() static inline.

Signed-off-by: Vikram Garhwal <vikram.garh...@amd.com>

---
Changes from v6:
    Rename "dt_node" to "from"
---
 xen/common/device_tree.c      |  6 ++++--
 xen/include/xen/device_tree.h | 18 ++++++++++++++++--
 2 files changed, 20 insertions(+), 4 deletions(-)

diff --git a/xen/common/device_tree.c b/xen/common/device_tree.c
index 16b4b4e946..c5250a1644 100644
--- a/xen/common/device_tree.c
+++ b/xen/common/device_tree.c
@@ -358,11 +358,13 @@ struct dt_device_node *dt_find_node_by_type(struct 
dt_device_node *from,
     return np;
 }
 
-struct dt_device_node *dt_find_node_by_path(const char *path)
+struct dt_device_node *
+                    device_tree_find_node_by_path(struct dt_device_node *from,
+                                                  const char *path)
 {
     struct dt_device_node *np;
 
-    dt_for_each_device_node(dt_host, np)
+    dt_for_each_device_node(from, np)
         if ( np->full_name && (dt_node_cmp(np->full_name, path) == 0) )
             break;
 
diff --git a/xen/include/xen/device_tree.h b/xen/include/xen/device_tree.h
index 2c35c0d391..e239f7de26 100644
--- a/xen/include/xen/device_tree.h
+++ b/xen/include/xen/device_tree.h
@@ -561,13 +561,27 @@ struct dt_device_node *dt_find_node_by_type(struct 
dt_device_node *from,
 struct dt_device_node *dt_find_node_by_alias(const char *alias);
 
 /**
- * dt_find_node_by_path - Find a node matching a full DT path
+ * device_tree_find_node_by_path - Generic function to find a node matching the
+ * full DT path for any given unflatten device tree
+ * @from: The device tree node to start searching from
  * @path: The full path to match
  *
  * Returns a node pointer.
  */
-struct dt_device_node *dt_find_node_by_path(const char *path);
+struct dt_device_node *
+                    device_tree_find_node_by_path(struct dt_device_node *from,
+                                                  const char *path);
 
+/**
+ * dt_find_node_by_path - Find a node matching a full DT path in dt_host
+ * @path: The full path to match
+ *
+ * Returns a node pointer.
+ */
+static inline struct dt_device_node *dt_find_node_by_path(const char *path)
+{
+    return device_tree_find_node_by_path(dt_host, path);
+}
 
 /**
  * dt_find_node_by_gpath - Same as dt_find_node_by_path but retrieve the
-- 
2.17.1