of: property: Add fw_devlink support for optional properties

Not all DT bindings are mandatory bindings. Add support for optional DT
bindings and mark iommus, iommu-map, dmas as optional DT bindings.
Tested-by: Marek Szyprowski <m.szyprowski@samsung.com>
Signed-off-by: Saravana Kannan <saravanak@google.com>
Link: https://lore.kernel.org/r/20210205222644.2357303-5-saravanak@google.comSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/of/property.c

@@ -1235,6 +1235,7 @@ static struct device_node *parse_##fname(struct device_node *np,	     \
 struct supplier_bindings {
 	struct device_node *(*parse_prop)(struct device_node *np,
 					  const char *prop_name, int index);
+	bool optional;
 };
 
 DEFINE_SIMPLE_PROP(clocks, "clocks", "#clock-cells")
@@ -1309,12 +1310,12 @@ static struct device_node *parse_interrupts(struct device_node *np,
 static const struct supplier_bindings of_supplier_bindings[] = {
 	{ .parse_prop = parse_clocks, },
 	{ .parse_prop = parse_interconnects, },
-	{ .parse_prop = parse_iommus, },
-	{ .parse_prop = parse_iommu_maps, },
+	{ .parse_prop = parse_iommus, .optional = true, },
+	{ .parse_prop = parse_iommu_maps, .optional = true, },
 	{ .parse_prop = parse_mboxes, },
 	{ .parse_prop = parse_io_channels, },
 	{ .parse_prop = parse_interrupt_parent, },
-	{ .parse_prop = parse_dmas, },
+	{ .parse_prop = parse_dmas, .optional = true, },
 	{ .parse_prop = parse_power_domains, },
 	{ .parse_prop = parse_hwlocks, },
 	{ .parse_prop = parse_extcon, },
@@ -1368,6 +1369,11 @@ static int of_link_property(struct device_node *con_np, const char *prop_name)
 
 	/* Do not stop at first failed link, link all available suppliers. */
 	while (!matched && s->parse_prop) {
+		if (s->optional && !fw_devlink_is_strict()) {
+			s++;
+			continue;
+		}
+
 		while ((phandle = s->parse_prop(con_np, prop_name, i))) {
 			matched = true;
 			i++;