of/overlay: Add overlay unittests

Add unittests for OF overlays.

It tests overlay device addition/removal and whether
the apply revert sequence is correct.

Changes since V1:
* Added local fixups entries.

Signed-off-by: Pantelis Antoniou <pantelis.antoniou@konsulko.com>
Signed-off-by: Grant Likely <grant.likely@linaro.org>

Documentation/devicetree/bindings/unittest.txt

@@ -0,0 +1,14 @@
+* OF selftest platform device
+
+** selftest
+
+Required properties:
+- compatible: must be "selftest"
+
+All other properties are optional.
+
+Example:
+	selftest {
+		compatible = "selftest";
+		status = "okay";
+	};

drivers/of/unittest-data/testcases.dts

@@ -13,6 +13,7 @@
 #include "tests-interrupts.dtsi"
 #include "tests-match.dtsi"
 #include "tests-platform.dtsi"
+#include "tests-overlay.dtsi"
 
 /*
  * phandle fixup data - generated by dtc patches that aren't upstream.
@@ -59,5 +60,20 @@
 		testcase-device2 {
 			interrupt-parent = <0x00000000>;
 		};
+		overlay2 {
+			fragment@0 {
+				target = <0x00000000>;
+			};
+		};
+		overlay3 {
+			fragment@0 {
+				target = <0x00000000>;
+			};
+		};
+		overlay4 {
+			fragment@0 {
+				target = <0x00000000>;
+			};
+		};
 	};
 }; };

drivers/of/unittest-data/tests-overlay.dtsi

@@ -0,0 +1,180 @@
+
+/ {
+	testcase-data {
+		overlay-node {
+
+			/* test bus */
+			selftestbus: test-bus {
+				compatible = "simple-bus";
+				#address-cells = <1>;
+				#size-cells = <0>;
+
+				selftest100: test-selftest100 {
+					compatible = "selftest";
+					status = "okay";
+					reg = <100>;
+				};
+
+				selftest101: test-selftest101 {
+					compatible = "selftest";
+					status = "disabled";
+					reg = <101>;
+				};
+
+				selftest0: test-selftest0 {
+					compatible = "selftest";
+					status = "disabled";
+					reg = <0>;
+				};
+
+				selftest1: test-selftest1 {
+					compatible = "selftest";
+					status = "okay";
+					reg = <1>;
+				};
+
+				selftest2: test-selftest2 {
+					compatible = "selftest";
+					status = "disabled";
+					reg = <2>;
+				};
+
+				selftest3: test-selftest3 {
+					compatible = "selftest";
+					status = "okay";
+					reg = <3>;
+				};
+
+				selftest5: test-selftest5 {
+					compatible = "selftest";
+					status = "disabled";
+					reg = <5>;
+				};
+
+				selftest6: test-selftest6 {
+					compatible = "selftest";
+					status = "disabled";
+					reg = <6>;
+				};
+
+				selftest7: test-selftest7 {
+					compatible = "selftest";
+					status = "disabled";
+					reg = <7>;
+				};
+
+				selftest8: test-selftest8 {
+					compatible = "selftest";
+					status = "disabled";
+					reg = <8>;
+				};
+			};
+		};
+
+		/* test enable using absolute target path */
+		overlay0 {
+			fragment@0 {
+				target-path = "/testcase-data/overlay-node/test-bus/test-selftest0";
+				__overlay__ {
+					status = "okay";
+				};
+			};
+		};
+
+		/* test disable using absolute target path */
+		overlay1 {
+			fragment@0 {
+				target-path = "/testcase-data/overlay-node/test-bus/test-selftest1";
+				__overlay__ {
+					status = "disabled";
+				};
+			};
+		};
+
+		/* test enable using label */
+		overlay2 {
+			fragment@0 {
+				target = <&selftest2>;
+				__overlay__ {
+					status = "okay";
+				};
+			};
+		};
+
+		/* test disable using label */
+		overlay3 {
+			fragment@0 {
+				target = <&selftest3>;
+				__overlay__ {
+					status = "disabled";
+				};
+			};
+		};
+
+		/* test insertion of a full node */
+		overlay4 {
+			fragment@0 {
+				target = <&selftestbus>;
+				__overlay__ {
+
+					/* suppress DTC warning */
+					#address-cells = <1>;
+					#size-cells = <0>;
+
+					test-selftest4 {
+						compatible = "selftest";
+						status = "okay";
+						reg = <4>;
+					};
+				};
+			};
+		};
+
+		/* test overlay apply revert */
+		overlay5 {
+			fragment@0 {
+				target-path = "/testcase-data/overlay-node/test-bus/test-selftest5";
+				__overlay__ {
+					status = "okay";
+				};
+			};
+		};
+
+		/* test overlays application and removal in sequence */
+		overlay6 {
+			fragment@0 {
+				target-path = "/testcase-data/overlay-node/test-bus/test-selftest6";
+				__overlay__ {
+					status = "okay";
+				};
+			};
+		};
+		overlay7 {
+			fragment@0 {
+				target-path = "/testcase-data/overlay-node/test-bus/test-selftest7";
+				__overlay__ {
+					status = "okay";
+				};
+			};
+		};
+
+		/* test overlays application and removal in bad sequence */
+		overlay8 {
+			fragment@0 {
+				target-path = "/testcase-data/overlay-node/test-bus/test-selftest8";
+				__overlay__ {
+					status = "okay";
+				};
+			};
+		};
+		overlay9 {
+			fragment@0 {
+				target-path = "/testcase-data/overlay-node/test-bus/test-selftest8";
+				__overlay__ {
+					property-foo = "bar";
+				};
+			};
+		};
+
+	};
+};