dm: core: Add a livetree function to check node status

Add a way to find out if a node is enabled or not, based on its 'status'
property.

Signed-off-by: Simon Glass <sjg@chromium.org>

drivers/core/ofnode.c

@@ -226,6 +226,16 @@ int ofnode_read_u32_array(ofnode node, const char *propname,
 	}
 }
 
+bool ofnode_is_enabled(ofnode node)
+{
+	if (ofnode_is_np(node)) {
+		return of_device_is_available(ofnode_to_np(node));
+	} else {
+		return fdtdec_get_is_enabled(gd->fdt_blob,
+					     ofnode_to_offset(node));
+	}
+}
+
 ofnode ofnode_first_subnode(ofnode node)
 {
 	assert(ofnode_valid(node));

include/dm/ofnode.h

@@ -345,6 +345,17 @@ const char *ofnode_read_string(ofnode node, const char *propname);
  */
 int ofnode_read_u32_array(ofnode node, const char *propname,
 			  u32 *out_values, size_t sz);
+/**
+ * ofnode_is_enabled() - Checks whether a node is enabled.
+ * This looks for a 'status' property. If this exists, then returns true if
+ * the status is 'okay' and false otherwise. If there is no status property,
+ * it returns true on the assumption that anything mentioned should be enabled
+ * by default.
+ *
+ * @node: node to examine
+ * @return false (not enabled) or true (enabled)
+ */
+bool ofnode_is_enabled(ofnode node);
 
 /**
  * ofnode_read_bool() - read a boolean value from a property

test/dm/ofnode.c

@@ -249,3 +249,15 @@ static int dm_test_ofnode_get_child_count(struct unit_test_state *uts)
 }
 DM_TEST(dm_test_ofnode_get_child_count,
 	UT_TESTF_SCAN_PDATA | UT_TESTF_SCAN_FDT);
+
+static int dm_test_ofnode_is_enabled(struct unit_test_state *uts)
+{
+	ofnode root_node = ofnode_path("/");
+	ofnode node = ofnode_path("/usb@0");
+
+	ut_assert(ofnode_is_enabled(root_node));
+	ut_assert(!ofnode_is_enabled(node));
+
+	return 0;
+}
+DM_TEST(dm_test_ofnode_is_enabled, UT_TESTF_SCAN_PDATA | UT_TESTF_SCAN_FDT);