of: property: Make it easy to add device links from DT properties

Add a DEFINE_SIMPLE_PROP macro to make it easy to add support for simple
properties with fixed names that just list phandles and phandle args.

Add a DEFINE_SUFFIX_PROP macro to make it easy to add support for
properties with fixes suffix that just list phandles and phandle args.

Signed-off-by: Saravana Kannan <saravanak@google.com>
Reviewed-by: Rob Herring <robh@kernel.org>
Link: https://lore.kernel.org/r/20191105065000.50407-3-saravanak@google.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/of/property.c

@@ -1101,17 +1101,11 @@ static struct device_node *parse_prop_cells(struct device_node *np,
 	return sup_args.np;
 }
 
-static struct device_node *parse_clocks(struct device_node *np,
-					const char *prop_name, int index)
-{
-	return parse_prop_cells(np, prop_name, index, "clocks", "#clock-cells");
-}
-
-static struct device_node *parse_interconnects(struct device_node *np,
-					       const char *prop_name, int index)
-{
-	return parse_prop_cells(np, prop_name, index, "interconnects",
-				"#interconnect-cells");
+#define DEFINE_SIMPLE_PROP(fname, name, cells)				  \
+static struct device_node *parse_##fname(struct device_node *np,	  \
+					const char *prop_name, int index) \
+{									  \
+	return parse_prop_cells(np, prop_name, index, name, cells);	  \
 }
 
 static int strcmp_suffix(const char *str, const char *suffix)
@@ -1125,13 +1119,47 @@ static int strcmp_suffix(const char *str, const char *suffix)
 	return strcmp(str + len - suffix_len, suffix);
 }
 
-static struct device_node *parse_regulators(struct device_node *np,
-					    const char *prop_name, int index)
+/**
+ * parse_suffix_prop_cells - Suffix property parsing function for suppliers
+ *
+ * @np:		Pointer to device tree node containing a list
+ * @prop_name:	Name of property to be parsed. Expected to hold phandle values
+ * @index:	For properties holding a list of phandles, this is the index
+ *		into the list.
+ * @suffix:	Property suffix that is known to contain list of phandle(s) to
+ *		supplier(s)
+ * @cells_name:	property name that specifies phandles' arguments count
+ *
+ * This is a helper function to parse properties that have a known fixed suffix
+ * and are a list of phandles and phandle arguments.
+ *
+ * Returns:
+ * - phandle node pointer with refcount incremented. Caller must of_node_put()
+ *   on it when done.
+ * - NULL if no phandle found at index
+ */
+static struct device_node *parse_suffix_prop_cells(struct device_node *np,
+					    const char *prop_name, int index,
+					    const char *suffix,
+					    const char *cells_name)
 {
-	if (index || strcmp_suffix(prop_name, "-supply"))
+	struct of_phandle_args sup_args;
+
+	if (strcmp_suffix(prop_name, suffix))
 		return NULL;
 
-	return of_parse_phandle(np, prop_name, 0);
+	if (of_parse_phandle_with_args(np, prop_name, cells_name, index,
+				       &sup_args))
+		return NULL;
+
+	return sup_args.np;
+}
+
+#define DEFINE_SUFFIX_PROP(fname, suffix, cells)			     \
+static struct device_node *parse_##fname(struct device_node *np,	     \
+					const char *prop_name, int index)    \
+{									     \
+	return parse_suffix_prop_cells(np, prop_name, index, suffix, cells); \
 }
 
 /**
@@ -1155,6 +1183,10 @@ struct supplier_bindings {
 					  const char *prop_name, int index);
 };
 
+DEFINE_SIMPLE_PROP(clocks, "clocks", "#clock-cells")
+DEFINE_SIMPLE_PROP(interconnects, "interconnects", "#interconnect-cells")
+DEFINE_SUFFIX_PROP(regulators, "-supply", NULL)
+
 static const struct supplier_bindings of_supplier_bindings[] = {
 	{ .parse_prop = parse_clocks, },
 	{ .parse_prop = parse_interconnects, },