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 <bgriffis@nvidia.com>
Signed-off-by: Thierry Reding <treding@nvidia.com>
Reviewed-by: Rob Herring (Arm) <robh@kernel.org>
Message-ID: <20241213141438.3616902-1-thierry.reding@gmail.com>
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>

checks.c

diff --git a/checks.c b/checks.c
index 9e6a7b6..123f2eb 100644
--- a/checks.c
+++ b/checks.c
@@ -1676,6 +1676,10 @@
 		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)