checks: Warn about missing #address-cells for interrupt parents

The device tree specification (v0.4) suggests that #address-cells is
mandatory for interrupt parent nodes. If this property is missing, Linux
will default to the value of 0.

A number of device tree files rely on Linux' fallback and don't specify
an explicit #address-cells as suggested by the specification. This can
cause issues when these device trees are passed to software with a more
pedantic interpretation of the DT spec.

Add a warning when this case is detected so that device tree files can
be fixed.

Reported-by: Brad Griffis <[email protected]>
Signed-off-by: Thierry Reding <[email protected]>
Reviewed-by: Rob Herring (Arm) <[email protected]>
Message-ID: <[email protected]>
Signed-off-by: David Gibson <[email protected]>

checks.c

@@ -1676,6 +1676,10 @@ static void check_interrupt_map(struct check *c,
 		cellprop = get_property(provider_node, "#address-cells");
 		if (cellprop)
 			parent_cellsize += propval_cell(cellprop);
+		else
+			FAIL_PROP(c, dti, node, irq_map_prop,
+				"Missing property '#address-cells' in node %s, using 0 as fallback",
+				provider_node->fullpath);
 
 		cell += 1 + parent_cellsize;
 		if (cell > map_cells)