checks: add a string check for 'label' property

Add a string property check for 'label' property. 'label' is a human
readable string typically used to identify connectors or ports on devices.

Signed-off-by: Rob Herring <robh@kernel.org>
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>

checks.c

@@ -586,6 +586,7 @@ WARNING_IF_NOT_CELL(interrupt_cells_is_cell, "#interrupt-cells");
 WARNING_IF_NOT_STRING(device_type_is_string, "device_type");
 WARNING_IF_NOT_STRING(model_is_string, "model");
 WARNING_IF_NOT_STRING(status_is_string, "status");
+WARNING_IF_NOT_STRING(label_is_string, "label");
 
 static void fixup_addr_size_cells(struct check *c, struct dt_info *dti,
 				  struct node *node)
@@ -1236,6 +1237,7 @@ static struct check *check_table[] = {
 
 	&address_cells_is_cell, &size_cells_is_cell, &interrupt_cells_is_cell,
 	&device_type_is_string, &model_is_string, &status_is_string,
+	&label_is_string,
 
 	&property_name_chars_strict,
 	&node_name_chars_strict,

tests/bad-string-props.dts

@@ -4,4 +4,5 @@
 	device_type = <0xdeadbeef>;
 	model = <0xdeadbeef>;
 	status = <0xdeadbeef>;
+	label = <0xdeadbeef>;
 };

tests/run_tests.sh

@@ -546,7 +546,7 @@ dtc_tests () {
     check_tests bad-name-property.dts name_properties
 
     check_tests bad-ncells.dts address_cells_is_cell size_cells_is_cell interrupt_cells_is_cell
-    check_tests bad-string-props.dts device_type_is_string model_is_string status_is_string
+    check_tests bad-string-props.dts device_type_is_string model_is_string status_is_string label_is_string
     check_tests bad-reg-ranges.dts reg_format ranges_format
     check_tests bad-empty-ranges.dts ranges_format
     check_tests reg-ranges-root.dts reg_format ranges_format