of/unittest: Show broken behaviour in the platform bus

Add a single resource to the test bus device to exercise the platform
bus code a little more. This isn't strictly a devicetree test, but it is
a corner case that the devicetree runs into. Until we've got platform
device unittests, it can live here. It doesn't need to be an explicit
text because the kernel will oops when it is wrong.

Cc: Pantelis Antoniou <pantelis.antoniou@konsulko.com>
Cc: Rob Herring <robh@kernel.org>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Ricardo Ribalda Delgado <ricardo.ribalda@gmail.com>
Signed-off-by: Grant Likely <grant.likely@linaro.org>
[wsa: added the comment provided by Grant, rebased, and tested]
Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Signed-off-by: Rob Herring <robh@kernel.org>

drivers/of/unittest.c

@@ -757,6 +757,11 @@ static void __init of_unittest_match_node(void)
 	}
 }
 
+static struct resource test_bus_res = {
+	.start = 0xfffffff8,
+	.end = 0xfffffff9,
+	.flags = IORESOURCE_MEM,
+};
 static const struct platform_device_info test_bus_info = {
 	.name = "unittest-bus",
 };
@@ -800,6 +805,15 @@ static void __init of_unittest_platform_populate(void)
 		return;
 	test_bus->dev.of_node = np;
 
+	/*
+	 * Add a dummy resource to the test bus node after it is
+	 * registered to catch problems with un-inserted resources. The
+	 * DT code doesn't insert the resources, and it has caused the
+	 * kernel to oops in the past. This makes sure the same bug
+	 * doesn't crop up again.
+	 */
+	platform_device_add_resources(test_bus, &test_bus_res, 1);
+
 	of_platform_populate(np, match, NULL, &test_bus->dev);
 	for_each_child_of_node(np, child) {
 		for_each_child_of_node(child, grandchild)