of: Add helpers for finding device nodes which have a given property

This commit adds a routine for finding a device node which has a
certain property.  The contents of the property are not taken into
account, merely the presence or absence of the property.

Based on that routine, we add a for_each_ macro for iterating over all
nodes that have a certain property.

Signed-off-by: Michael Ellerman <michael@ellerman.id.au>
Signed-off-by: Paul Mackerras <paulus@samba.org>

diff --git a/drivers/of/base.c b/drivers/of/base.c
index 7c79e94a35eac932a165367a11439a8af1d35cc0..4f884a358a7bcce37d24dce2c4a622dd41c01362 100644 (file)
--- a/drivers/of/base.c
+++ b/drivers/of/base.c
@@ -328,6 +328,41 @@ struct device_node *of_find_compatible_node(struct device_node *from,
 }
 EXPORT_SYMBOL(of_find_compatible_node);
 
+/**
+ *     of_find_node_with_property - Find a node which has a property with
+ *                                   the given name.
+ *     @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
+ *     @prop_name:     The name of the property to look for.
+ *
+ *     Returns a node pointer with refcount incremented, use
+ *     of_node_put() on it when done.
+ */
+struct device_node *of_find_node_with_property(struct device_node *from,
+       const char *prop_name)
+{
+       struct device_node *np;
+       struct property *pp;
+
+       read_lock(&devtree_lock);
+       np = from ? from->allnext : allnodes;
+       for (; np; np = np->allnext) {
+               for (pp = np->properties; pp != 0; pp = pp->next) {
+                       if (of_prop_cmp(pp->name, prop_name) == 0) {
+                               of_node_get(np);
+                               goto out;
+                       }
+               }
+       }
+out:
+       of_node_put(from);
+       read_unlock(&devtree_lock);
+       return np;
+}
+EXPORT_SYMBOL(of_find_node_with_property);
+
 /**
  * of_match_node - Tell if an device_node has a matching of_match structure
  *     @matches:       array of of device match structures to search in

diff --git a/include/linux/of.h b/include/linux/of.h
index e2488f5e7cb2bfc4ab275b1a2685bba103713205..6a7efa242f5e50dd7c1b87f25c75a47a25964cc1 100644 (file)
--- a/include/linux/of.h
+++ b/include/linux/of.h
@@ -57,6 +57,12 @@ extern struct device_node *of_get_next_child(const struct device_node *node,
        for (child = of_get_next_child(parent, NULL); child != NULL; \
             child = of_get_next_child(parent, child))
 
+extern struct device_node *of_find_node_with_property(
+       struct device_node *from, const char *prop_name);
+#define for_each_node_with_property(dn, prop_name) \
+       for (dn = of_find_node_with_property(NULL, prop_name); dn; \
+            dn = of_find_node_with_property(dn, prop_name))
+
 extern struct property *of_find_property(const struct device_node *np,
                                         const char *name,
                                         int *lenp);