thunderbolt: Introduce tb_for_each_upstream_port_on_path()

This is useful when walking over upstream lane adapters over given path.
Signed-off-by: Mika Westerberg <mika.westerberg@linux.intel.com>

drivers/thunderbolt/tb.h

@@ -1073,6 +1073,21 @@ static inline bool tb_port_use_credit_allocation(const struct tb_port *port)
 	for ((p) = tb_next_port_on_path((src), (dst), NULL); (p);	\
 	     (p) = tb_next_port_on_path((src), (dst), (p)))
 
+/**
+ * tb_for_each_upstream_port_on_path() - Iterate over each upstreamm port on path
+ * @src: Source port
+ * @dst: Destination port
+ * @p: Port used as iterator
+ *
+ * Walks over each upstream lane adapter on path from @src to @dst.
+ */
+#define tb_for_each_upstream_port_on_path(src, dst, p)			\
+	for ((p) = tb_next_port_on_path((src), (dst), NULL); (p);	\
+	     (p) = tb_next_port_on_path((src), (dst), (p)))		\
+		if (!tb_port_is_null((p)) || !tb_is_upstream_port((p))) {\
+			continue;					\
+		} else
+
 int tb_port_get_link_speed(struct tb_port *port);
 int tb_port_get_link_generation(struct tb_port *port);
 int tb_port_get_link_width(struct tb_port *port);