of: introduce for_each_matching_node_and_match()

The following pattern of code is tempting:

    for_each_matching_node(np, table) {
        match = of_match_node(table, np);

However, this results in iterating over table twice; the second time
inside of_match_node(). The implementation of for_each_matching_node()
already found the match, so this is redundant. Invent new function
of_find_matching_node_and_match() and macro
for_each_matching_node_and_match() to remove the double iteration,
thus transforming the above code to:

    for_each_matching_node_and_match(np, table, &match)

Signed-off-by: Stephen Warren <swarren@nvidia.com>
Signed-off-by: Rob Herring <rob.herring@calxeda.com>

2 files changed, 26 insertions, 7 deletions

diff --git a/drivers/of/base.c b/drivers/of/base.c
index f564e3107b3..0ceb26a1605 100644
--- a/drivers/of/base.c
+++ b/drivers/of/base.c
@@ -594,27 +594,35 @@ const struct of_device_id *of_match_node(const struct of_device_id *matches,
 EXPORT_SYMBOL(of_match_node);
 
 /**
- *      of_find_matching_node - Find a node based on an of_device_id match
- *                              table.
+ *      of_find_matching_node_and_match - Find a node based on an of_device_id
+ *                                        match table.
  *      @from:          The node to start searching from or NULL, the node
  *                      you pass will not be searched, only the next one
  *                      will; typically, you pass what the previous call
  *                      returned. of_node_put() will be called on it
  *      @matches:       array of of device match structures to search in
+ *      @match          Updated to point at the matches entry which matched
  *
  *      Returns a node pointer with refcount incremented, use
  *      of_node_put() on it when done.
  */
-struct device_node *of_find_matching_node(struct device_node *from,
-                                          const struct of_device_id *matches)
+struct device_node *of_find_matching_node_and_match(struct device_node *from,
+                                        const struct of_device_id *matches,
+                                        const struct of_device_id **match)
 {
         struct device_node *np;
 
+        if (match)
+                *match = NULL;
+
         read_lock(&devtree_lock);
         np = from ? from->allnext : allnodes;
         for (; np; np = np->allnext) {
-                if (of_match_node(matches, np) && of_node_get(np))
+                if (of_match_node(matches, np) && of_node_get(np)) {
+                        if (match)
+                                *match = matches;
                         break;
+                }
         }
         of_node_put(from);
         read_unlock(&devtree_lock);
diff --git a/include/linux/of.h b/include/linux/of.h
index ab1af0e1465..13e0aacb4d9 100644
--- a/include/linux/of.h
+++ b/include/linux/of.h
@@ -179,11 +179,22 @@ extern struct device_node *of_find_compatible_node(struct device_node *from,
 #define for_each_compatible_node(dn, type, compatible) \
         for (dn = of_find_compatible_node(NULL, type, compatible); dn; \
              dn = of_find_compatible_node(dn, type, compatible))
-extern struct device_node *of_find_matching_node(struct device_node *from,
-        const struct of_device_id *matches);
+extern struct device_node *of_find_matching_node_and_match(
+        struct device_node *from,
+        const struct of_device_id *matches,
+        const struct of_device_id **match);
+static inline struct device_node *of_find_matching_node(
+        struct device_node *from,
+        const struct of_device_id *matches)
+{
+        return of_find_matching_node_and_match(from, matches, NULL);
+}
 #define for_each_matching_node(dn, matches) \
         for (dn = of_find_matching_node(NULL, matches); dn; \
              dn = of_find_matching_node(dn, matches))
+#define for_each_matching_node_and_match(dn, matches, match) \
+        for (dn = of_find_matching_node_and_match(NULL, matches, match); \
+             dn; dn = of_find_matching_node_and_match(dn, matches, match))
 extern struct device_node *of_find_node_by_path(const char *path);
 extern struct device_node *of_find_node_by_phandle(phandle handle);
 extern struct device_node *of_get_parent(const struct device_node *node);