[PATCH RFC 4/4] of: unittest: cover /aliases updates from overlay apply/revert

[Abdurrahman Hussain]

Add overlay_alias.dtso, which declares `testcase-alias99 = ...` under
/aliases via the &{/aliases} shorthand, and an of_unittest_overlay_alias()
runner that:

  1. asserts of_alias_get_id(target, "testcase-alias") is -ENODEV
     before the overlay is applied,
  2. applies the overlay and asserts the same call now returns 99,
  3. removes the overlay and asserts we're back to -ENODEV.

Exercises all three functional patches earlier in this series
together: patch 1's reconfig notifier is what mutates aliases_lookup
on apply/revert, patch 2 is what lets target-path="/aliases" resolve
to the DT root when target_base is non-NULL, and patch 3 is what
rewrites the fragment-internal path in the alias value so
of_find_node_by_path() finds the live-tree target. Any one of the
three missing turns the middle assertion (get_id -> 99) into
-ENODEV.

Signed-off-by: Abdurrahman Hussain <abdurrahman@xxxxxxxxxx>
---
 drivers/of/unittest-data/Makefile           |  2 ++
 drivers/of/unittest-data/overlay_alias.dtso |  9 +++++
 drivers/of/unittest.c                       | 51 +++++++++++++++++++++++++++++
 3 files changed, 62 insertions(+)

diff --git a/drivers/of/unittest-data/Makefile b/drivers/of/unittest-data/Makefile
index 01a966e39f23..0a8bd9a74283 100644
--- a/drivers/of/unittest-data/Makefile
+++ b/drivers/of/unittest-data/Makefile
@@ -22,6 +22,7 @@ obj-$(CONFIG_OF_OVERLAY) += overlay.dtbo.o \
 			    overlay_18.dtbo.o \
 			    overlay_19.dtbo.o \
 			    overlay_20.dtbo.o \
+			    overlay_alias.dtbo.o \
 			    overlay_bad_add_dup_node.dtbo.o \
 			    overlay_bad_add_dup_prop.dtbo.o \
 			    overlay_bad_phandle.dtbo.o \
@@ -87,6 +88,7 @@ apply_static_overlay_1 := overlay_0.dtbo \
 			  overlay_18.dtbo \
 			  overlay_19.dtbo \
 			  overlay_20.dtbo \
+			  overlay_alias.dtbo \
 			  overlay_gpio_01.dtbo \
 			  overlay_gpio_02a.dtbo \
 			  overlay_gpio_02b.dtbo \
diff --git a/drivers/of/unittest-data/overlay_alias.dtso b/drivers/of/unittest-data/overlay_alias.dtso
new file mode 100644
index 000000000000..32532c80505a
--- /dev/null
+++ b/drivers/of/unittest-data/overlay_alias.dtso
@@ -0,0 +1,9 @@
+// SPDX-License-Identifier: GPL-2.0
+/dts-v1/;
+/plugin/;
+
+/* overlay_alias - declare an alias inside an overlay */
+
+&{/aliases} {
+	testcase-alias99 = "/testcase-data/overlay-node/test-bus/test-unittest100";
+};
diff --git a/drivers/of/unittest.c b/drivers/of/unittest.c
index e255f54f4d76..a9f4a0bb3087 100644
--- a/drivers/of/unittest.c
+++ b/drivers/of/unittest.c
@@ -3475,6 +3475,53 @@ static struct notifier_block of_nb = {
 	.notifier_call = of_notify,
 };
 
+static void __init of_unittest_overlay_alias(void)
+{
+	const char *path = "/testcase-data/overlay-node/test-bus/test-unittest100";
+	struct device_node *np;
+	int ovcs_id = 0;
+	int id, ret;
+
+	np = of_find_node_by_path(path);
+	if (!np) {
+		unittest(0, "could not find %s for alias test\n", path);
+		return;
+	}
+
+	id = of_alias_get_id(np, "testcase-alias");
+	if (id != -ENODEV) {
+		unittest(0,
+			 "of_alias_get_id() = %d before overlay, expected -ENODEV\n",
+			 id);
+		goto out;
+	}
+
+	ret = overlay_data_apply("overlay_alias", &ovcs_id);
+	if (!ret) {
+		unittest(0, "overlay_alias apply failed\n");
+		goto out;
+	}
+
+	id = of_alias_get_id(np, "testcase-alias");
+	unittest(id == 99,
+		 "of_alias_get_id() = %d after overlay apply, expected 99\n", id);
+
+	ret = of_overlay_remove(&ovcs_id);
+	if (ret) {
+		unittest(0, "overlay_alias remove failed, ret = %d\n", ret);
+		goto out;
+	}
+
+	id = of_alias_get_id(np, "testcase-alias");
+	unittest(id == -ENODEV,
+		 "of_alias_get_id() = %d after overlay remove, expected -ENODEV\n",
+		 id);
+
+	unittest(1, "overlay alias test passed\n");
+out:
+	of_node_put(np);
+}
+
 static void __init of_unittest_overlay_notify(void)
 {
 	int ovcs_id;
@@ -3649,6 +3696,8 @@ static void __init of_unittest_overlay(void)
 
 	of_unittest_overlay_gpio();
 
+	of_unittest_overlay_alias();
+
 	of_unittest_remove_tracked_overlays();
 
 	of_unittest_overlay_notify();
@@ -3848,6 +3897,7 @@ OVERLAY_INFO_EXTERN(overlay_17);
 OVERLAY_INFO_EXTERN(overlay_18);
 OVERLAY_INFO_EXTERN(overlay_19);
 OVERLAY_INFO_EXTERN(overlay_20);
+OVERLAY_INFO_EXTERN(overlay_alias);
 OVERLAY_INFO_EXTERN(overlay_gpio_01);
 OVERLAY_INFO_EXTERN(overlay_gpio_02a);
 OVERLAY_INFO_EXTERN(overlay_gpio_02b);
@@ -3885,6 +3935,7 @@ static struct overlay_info overlays[] = {
 	OVERLAY_INFO(overlay_18, 0, 0),
 	OVERLAY_INFO(overlay_19, 0, 0),
 	OVERLAY_INFO(overlay_20, 0, 0),
+	OVERLAY_INFO(overlay_alias, 0, 0),
 	OVERLAY_INFO(overlay_gpio_01, 0, 0),
 	OVERLAY_INFO(overlay_gpio_02a, 0, 0),
 	OVERLAY_INFO(overlay_gpio_02b, 0, 0),

-- 
2.54.0