diff --git a/drivers/of/unittest.c b/drivers/of/unittest.c
new file mode 100644
index 0000000..41b4971
--- /dev/null
+++ b/drivers/of/unittest.c
@@ -0,0 +1,2490 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Self tests for device tree subsystem
+ */
+
+#define pr_fmt(fmt) "### dt-test ### " fmt
+
+#include <linux/bootmem.h>
+#include <linux/clk.h>
+#include <linux/err.h>
+#include <linux/errno.h>
+#include <linux/hashtable.h>
+#include <linux/libfdt.h>
+#include <linux/of.h>
+#include <linux/of_fdt.h>
+#include <linux/of_irq.h>
+#include <linux/of_platform.h>
+#include <linux/list.h>
+#include <linux/mutex.h>
+#include <linux/slab.h>
+#include <linux/device.h>
+#include <linux/platform_device.h>
+
+#include <linux/i2c.h>
+#include <linux/i2c-mux.h>
+
+#include <linux/bitops.h>
+
+#include "of_private.h"
+
+static struct unittest_results {
+	int passed;
+	int failed;
+} unittest_results;
+
+#define unittest(result, fmt, ...) ({ \
+	bool failed = !(result); \
+	if (failed) { \
+		unittest_results.failed++; \
+		pr_err("FAIL %s():%i " fmt, __func__, __LINE__, ##__VA_ARGS__); \
+	} else { \
+		unittest_results.passed++; \
+		pr_debug("pass %s():%i\n", __func__, __LINE__); \
+	} \
+	failed; \
+})
+
+static void __init of_unittest_find_node_by_name(void)
+{
+	struct device_node *np;
+	const char *options, *name;
+
+	np = of_find_node_by_path("/testcase-data");
+	name = kasprintf(GFP_KERNEL, "%pOF", np);
+	unittest(np && !strcmp("/testcase-data", name),
+		"find /testcase-data failed\n");
+	of_node_put(np);
+	kfree(name);
+
+	/* Test if trailing '/' works */
+	np = of_find_node_by_path("/testcase-data/");
+	unittest(!np, "trailing '/' on /testcase-data/ should fail\n");
+
+	np = of_find_node_by_path("/testcase-data/phandle-tests/consumer-a");
+	name = kasprintf(GFP_KERNEL, "%pOF", np);
+	unittest(np && !strcmp("/testcase-data/phandle-tests/consumer-a", name),
+		"find /testcase-data/phandle-tests/consumer-a failed\n");
+	of_node_put(np);
+	kfree(name);
+
+	np = of_find_node_by_path("testcase-alias");
+	name = kasprintf(GFP_KERNEL, "%pOF", np);
+	unittest(np && !strcmp("/testcase-data", name),
+		"find testcase-alias failed\n");
+	of_node_put(np);
+	kfree(name);
+
+	/* Test if trailing '/' works on aliases */
+	np = of_find_node_by_path("testcase-alias/");
+	unittest(!np, "trailing '/' on testcase-alias/ should fail\n");
+
+	np = of_find_node_by_path("testcase-alias/phandle-tests/consumer-a");
+	name = kasprintf(GFP_KERNEL, "%pOF", np);
+	unittest(np && !strcmp("/testcase-data/phandle-tests/consumer-a", name),
+		"find testcase-alias/phandle-tests/consumer-a failed\n");
+	of_node_put(np);
+	kfree(name);
+
+	np = of_find_node_by_path("/testcase-data/missing-path");
+	unittest(!np, "non-existent path returned node %pOF\n", np);
+	of_node_put(np);
+
+	np = of_find_node_by_path("missing-alias");
+	unittest(!np, "non-existent alias returned node %pOF\n", np);
+	of_node_put(np);
+
+	np = of_find_node_by_path("testcase-alias/missing-path");
+	unittest(!np, "non-existent alias with relative path returned node %pOF\n", np);
+	of_node_put(np);
+
+	np = of_find_node_opts_by_path("/testcase-data:testoption", &options);
+	unittest(np && !strcmp("testoption", options),
+		 "option path test failed\n");
+	of_node_put(np);
+
+	np = of_find_node_opts_by_path("/testcase-data:test/option", &options);
+	unittest(np && !strcmp("test/option", options),
+		 "option path test, subcase #1 failed\n");
+	of_node_put(np);
+
+	np = of_find_node_opts_by_path("/testcase-data/testcase-device1:test/option", &options);
+	unittest(np && !strcmp("test/option", options),
+		 "option path test, subcase #2 failed\n");
+	of_node_put(np);
+
+	np = of_find_node_opts_by_path("/testcase-data:testoption", NULL);
+	unittest(np, "NULL option path test failed\n");
+	of_node_put(np);
+
+	np = of_find_node_opts_by_path("testcase-alias:testaliasoption",
+				       &options);
+	unittest(np && !strcmp("testaliasoption", options),
+		 "option alias path test failed\n");
+	of_node_put(np);
+
+	np = of_find_node_opts_by_path("testcase-alias:test/alias/option",
+				       &options);
+	unittest(np && !strcmp("test/alias/option", options),
+		 "option alias path test, subcase #1 failed\n");
+	of_node_put(np);
+
+	np = of_find_node_opts_by_path("testcase-alias:testaliasoption", NULL);
+	unittest(np, "NULL option alias path test failed\n");
+	of_node_put(np);
+
+	options = "testoption";
+	np = of_find_node_opts_by_path("testcase-alias", &options);
+	unittest(np && !options, "option clearing test failed\n");
+	of_node_put(np);
+
+	options = "testoption";
+	np = of_find_node_opts_by_path("/", &options);
+	unittest(np && !options, "option clearing root node test failed\n");
+	of_node_put(np);
+}
+
+static void __init of_unittest_dynamic(void)
+{
+	struct device_node *np;
+	struct property *prop;
+
+	np = of_find_node_by_path("/testcase-data");
+	if (!np) {
+		pr_err("missing testcase data\n");
+		return;
+	}
+
+	/* Array of 4 properties for the purpose of testing */
+	prop = kcalloc(4, sizeof(*prop), GFP_KERNEL);
+	if (!prop) {
+		unittest(0, "kzalloc() failed\n");
+		return;
+	}
+
+	/* Add a new property - should pass*/
+	prop->name = "new-property";
+	prop->value = "new-property-data";
+	prop->length = strlen(prop->value) + 1;
+	unittest(of_add_property(np, prop) == 0, "Adding a new property failed\n");
+
+	/* Try to add an existing property - should fail */
+	prop++;
+	prop->name = "new-property";
+	prop->value = "new-property-data-should-fail";
+	prop->length = strlen(prop->value) + 1;
+	unittest(of_add_property(np, prop) != 0,
+		 "Adding an existing property should have failed\n");
+
+	/* Try to modify an existing property - should pass */
+	prop->value = "modify-property-data-should-pass";
+	prop->length = strlen(prop->value) + 1;
+	unittest(of_update_property(np, prop) == 0,
+		 "Updating an existing property should have passed\n");
+
+	/* Try to modify non-existent property - should pass*/
+	prop++;
+	prop->name = "modify-property";
+	prop->value = "modify-missing-property-data-should-pass";
+	prop->length = strlen(prop->value) + 1;
+	unittest(of_update_property(np, prop) == 0,
+		 "Updating a missing property should have passed\n");
+
+	/* Remove property - should pass */
+	unittest(of_remove_property(np, prop) == 0,
+		 "Removing a property should have passed\n");
+
+	/* Adding very large property - should pass */
+	prop++;
+	prop->name = "large-property-PAGE_SIZEx8";
+	prop->length = PAGE_SIZE * 8;
+	prop->value = kzalloc(prop->length, GFP_KERNEL);
+	unittest(prop->value != NULL, "Unable to allocate large buffer\n");
+	if (prop->value)
+		unittest(of_add_property(np, prop) == 0,
+			 "Adding a large property should have passed\n");
+}
+
+static int __init of_unittest_check_node_linkage(struct device_node *np)
+{
+	struct device_node *child;
+	int count = 0, rc;
+
+	for_each_child_of_node(np, child) {
+		if (child->parent != np) {
+			pr_err("Child node %s links to wrong parent %s\n",
+				 child->name, np->name);
+			rc = -EINVAL;
+			goto put_child;
+		}
+
+		rc = of_unittest_check_node_linkage(child);
+		if (rc < 0)
+			goto put_child;
+		count += rc;
+	}
+
+	return count + 1;
+put_child:
+	of_node_put(child);
+	return rc;
+}
+
+static void __init of_unittest_check_tree_linkage(void)
+{
+	struct device_node *np;
+	int allnode_count = 0, child_count;
+
+	if (!of_root)
+		return;
+
+	for_each_of_allnodes(np)
+		allnode_count++;
+	child_count = of_unittest_check_node_linkage(of_root);
+
+	unittest(child_count > 0, "Device node data structure is corrupted\n");
+	unittest(child_count == allnode_count,
+		 "allnodes list size (%i) doesn't match sibling lists size (%i)\n",
+		 allnode_count, child_count);
+	pr_debug("allnodes list size (%i); sibling lists size (%i)\n", allnode_count, child_count);
+}
+
+static void __init of_unittest_printf_one(struct device_node *np, const char *fmt,
+					  const char *expected)
+{
+	unsigned char *buf;
+	int buf_size;
+	int size, i;
+
+	buf_size = strlen(expected) + 10;
+	buf = kmalloc(buf_size, GFP_KERNEL);
+	if (!buf)
+		return;
+
+	/* Baseline; check conversion with a large size limit */
+	memset(buf, 0xff, buf_size);
+	size = snprintf(buf, buf_size - 2, fmt, np);
+
+	/* use strcmp() instead of strncmp() here to be absolutely sure strings match */
+	unittest((strcmp(buf, expected) == 0) && (buf[size+1] == 0xff),
+		"sprintf failed; fmt='%s' expected='%s' rslt='%s'\n",
+		fmt, expected, buf);
+
+	/* Make sure length limits work */
+	size++;
+	for (i = 0; i < 2; i++, size--) {
+		/* Clear the buffer, and make sure it works correctly still */
+		memset(buf, 0xff, buf_size);
+		snprintf(buf, size+1, fmt, np);
+		unittest(strncmp(buf, expected, size) == 0 && (buf[size+1] == 0xff),
+			"snprintf failed; size=%i fmt='%s' expected='%s' rslt='%s'\n",
+			size, fmt, expected, buf);
+	}
+	kfree(buf);
+}
+
+static void __init of_unittest_printf(void)
+{
+	struct device_node *np;
+	const char *full_name = "/testcase-data/platform-tests/test-device@1/dev@100";
+	char phandle_str[16] = "";
+
+	np = of_find_node_by_path(full_name);
+	if (!np) {
+		unittest(np, "testcase data missing\n");
+		return;
+	}
+
+	num_to_str(phandle_str, sizeof(phandle_str), np->phandle, 0);
+
+	of_unittest_printf_one(np, "%pOF",  full_name);
+	of_unittest_printf_one(np, "%pOFf", full_name);
+	of_unittest_printf_one(np, "%pOFp", phandle_str);
+	of_unittest_printf_one(np, "%pOFP", "dev@100");
+	of_unittest_printf_one(np, "ABC %pOFP ABC", "ABC dev@100 ABC");
+	of_unittest_printf_one(np, "%10pOFP", "   dev@100");
+	of_unittest_printf_one(np, "%-10pOFP", "dev@100   ");
+	of_unittest_printf_one(of_root, "%pOFP", "/");
+	of_unittest_printf_one(np, "%pOFF", "----");
+	of_unittest_printf_one(np, "%pOFPF", "dev@100:----");
+	of_unittest_printf_one(np, "%pOFPFPc", "dev@100:----:dev@100:test-sub-device");
+	of_unittest_printf_one(np, "%pOFc", "test-sub-device");
+	of_unittest_printf_one(np, "%pOFC",
+			"\"test-sub-device\",\"test-compat2\",\"test-compat3\"");
+}
+
+struct node_hash {
+	struct hlist_node node;
+	struct device_node *np;
+};
+
+static DEFINE_HASHTABLE(phandle_ht, 8);
+static void __init of_unittest_check_phandles(void)
+{
+	struct device_node *np;
+	struct node_hash *nh;
+	struct hlist_node *tmp;
+	int i, dup_count = 0, phandle_count = 0;
+
+	for_each_of_allnodes(np) {
+		if (!np->phandle)
+			continue;
+
+		hash_for_each_possible(phandle_ht, nh, node, np->phandle) {
+			if (nh->np->phandle == np->phandle) {
+				pr_info("Duplicate phandle! %i used by %pOF and %pOF\n",
+					np->phandle, nh->np, np);
+				dup_count++;
+				break;
+			}
+		}
+
+		nh = kzalloc(sizeof(*nh), GFP_KERNEL);
+		if (WARN_ON(!nh))
+			return;
+
+		nh->np = np;
+		hash_add(phandle_ht, &nh->node, np->phandle);
+		phandle_count++;
+	}
+	unittest(dup_count == 0, "Found %i duplicates in %i phandles\n",
+		 dup_count, phandle_count);
+
+	/* Clean up */
+	hash_for_each_safe(phandle_ht, i, tmp, nh, node) {
+		hash_del(&nh->node);
+		kfree(nh);
+	}
+}
+
+static void __init of_unittest_parse_phandle_with_args(void)
+{
+	struct device_node *np;
+	struct of_phandle_args args;
+	int i, rc;
+
+	np = of_find_node_by_path("/testcase-data/phandle-tests/consumer-a");
+	if (!np) {
+		pr_err("missing testcase data\n");
+		return;
+	}
+
+	rc = of_count_phandle_with_args(np, "phandle-list", "#phandle-cells");
+	unittest(rc == 7, "of_count_phandle_with_args() returned %i, expected 7\n", rc);
+
+	for (i = 0; i < 8; i++) {
+		bool passed = true;
+
+		rc = of_parse_phandle_with_args(np, "phandle-list",
+						"#phandle-cells", i, &args);
+
+		/* Test the values from tests-phandle.dtsi */
+		switch (i) {
+		case 0:
+			passed &= !rc;
+			passed &= (args.args_count == 1);
+			passed &= (args.args[0] == (i + 1));
+			break;
+		case 1:
+			passed &= !rc;
+			passed &= (args.args_count == 2);
+			passed &= (args.args[0] == (i + 1));
+			passed &= (args.args[1] == 0);
+			break;
+		case 2:
+			passed &= (rc == -ENOENT);
+			break;
+		case 3:
+			passed &= !rc;
+			passed &= (args.args_count == 3);
+			passed &= (args.args[0] == (i + 1));
+			passed &= (args.args[1] == 4);
+			passed &= (args.args[2] == 3);
+			break;
+		case 4:
+			passed &= !rc;
+			passed &= (args.args_count == 2);
+			passed &= (args.args[0] == (i + 1));
+			passed &= (args.args[1] == 100);
+			break;
+		case 5:
+			passed &= !rc;
+			passed &= (args.args_count == 0);
+			break;
+		case 6:
+			passed &= !rc;
+			passed &= (args.args_count == 1);
+			passed &= (args.args[0] == (i + 1));
+			break;
+		case 7:
+			passed &= (rc == -ENOENT);
+			break;
+		default:
+			passed = false;
+		}
+
+		unittest(passed, "index %i - data error on node %pOF rc=%i\n",
+			 i, args.np, rc);
+	}
+
+	/* Check for missing list property */
+	rc = of_parse_phandle_with_args(np, "phandle-list-missing",
+					"#phandle-cells", 0, &args);
+	unittest(rc == -ENOENT, "expected:%i got:%i\n", -ENOENT, rc);
+	rc = of_count_phandle_with_args(np, "phandle-list-missing",
+					"#phandle-cells");
+	unittest(rc == -ENOENT, "expected:%i got:%i\n", -ENOENT, rc);
+
+	/* Check for missing cells property */
+	rc = of_parse_phandle_with_args(np, "phandle-list",
+					"#phandle-cells-missing", 0, &args);
+	unittest(rc == -EINVAL, "expected:%i got:%i\n", -EINVAL, rc);
+	rc = of_count_phandle_with_args(np, "phandle-list",
+					"#phandle-cells-missing");
+	unittest(rc == -EINVAL, "expected:%i got:%i\n", -EINVAL, rc);
+
+	/* Check for bad phandle in list */
+	rc = of_parse_phandle_with_args(np, "phandle-list-bad-phandle",
+					"#phandle-cells", 0, &args);
+	unittest(rc == -EINVAL, "expected:%i got:%i\n", -EINVAL, rc);
+	rc = of_count_phandle_with_args(np, "phandle-list-bad-phandle",
+					"#phandle-cells");
+	unittest(rc == -EINVAL, "expected:%i got:%i\n", -EINVAL, rc);
+
+	/* Check for incorrectly formed argument list */
+	rc = of_parse_phandle_with_args(np, "phandle-list-bad-args",
+					"#phandle-cells", 1, &args);
+	unittest(rc == -EINVAL, "expected:%i got:%i\n", -EINVAL, rc);
+	rc = of_count_phandle_with_args(np, "phandle-list-bad-args",
+					"#phandle-cells");
+	unittest(rc == -EINVAL, "expected:%i got:%i\n", -EINVAL, rc);
+}
+
+static void __init of_unittest_parse_phandle_with_args_map(void)
+{
+	struct device_node *np, *p0, *p1, *p2, *p3;
+	struct of_phandle_args args;
+	int i, rc;
+
+	np = of_find_node_by_path("/testcase-data/phandle-tests/consumer-b");
+	if (!np) {
+		pr_err("missing testcase data\n");
+		return;
+	}
+
+	p0 = of_find_node_by_path("/testcase-data/phandle-tests/provider0");
+	if (!p0) {
+		pr_err("missing testcase data\n");
+		return;
+	}
+
+	p1 = of_find_node_by_path("/testcase-data/phandle-tests/provider1");
+	if (!p1) {
+		pr_err("missing testcase data\n");
+		return;
+	}
+
+	p2 = of_find_node_by_path("/testcase-data/phandle-tests/provider2");
+	if (!p2) {
+		pr_err("missing testcase data\n");
+		return;
+	}
+
+	p3 = of_find_node_by_path("/testcase-data/phandle-tests/provider3");
+	if (!p3) {
+		pr_err("missing testcase data\n");
+		return;
+	}
+
+	rc = of_count_phandle_with_args(np, "phandle-list", "#phandle-cells");
+	unittest(rc == 7, "of_count_phandle_with_args() returned %i, expected 7\n", rc);
+
+	for (i = 0; i < 8; i++) {
+		bool passed = true;
+
+		rc = of_parse_phandle_with_args_map(np, "phandle-list",
+						    "phandle", i, &args);
+
+		/* Test the values from tests-phandle.dtsi */
+		switch (i) {
+		case 0:
+			passed &= !rc;
+			passed &= (args.np == p1);
+			passed &= (args.args_count == 1);
+			passed &= (args.args[0] == 1);
+			break;
+		case 1:
+			passed &= !rc;
+			passed &= (args.np == p3);
+			passed &= (args.args_count == 3);
+			passed &= (args.args[0] == 2);
+			passed &= (args.args[1] == 5);
+			passed &= (args.args[2] == 3);
+			break;
+		case 2:
+			passed &= (rc == -ENOENT);
+			break;
+		case 3:
+			passed &= !rc;
+			passed &= (args.np == p0);
+			passed &= (args.args_count == 0);
+			break;
+		case 4:
+			passed &= !rc;
+			passed &= (args.np == p1);
+			passed &= (args.args_count == 1);
+			passed &= (args.args[0] == 3);
+			break;
+		case 5:
+			passed &= !rc;
+			passed &= (args.np == p0);
+			passed &= (args.args_count == 0);
+			break;
+		case 6:
+			passed &= !rc;
+			passed &= (args.np == p2);
+			passed &= (args.args_count == 2);
+			passed &= (args.args[0] == 15);
+			passed &= (args.args[1] == 0x20);
+			break;
+		case 7:
+			passed &= (rc == -ENOENT);
+			break;
+		default:
+			passed = false;
+		}
+
+		unittest(passed, "index %i - data error on node %s rc=%i\n",
+			 i, args.np->full_name, rc);
+	}
+
+	/* Check for missing list property */
+	rc = of_parse_phandle_with_args_map(np, "phandle-list-missing",
+					    "phandle", 0, &args);
+	unittest(rc == -ENOENT, "expected:%i got:%i\n", -ENOENT, rc);
+
+	/* Check for missing cells,map,mask property */
+	rc = of_parse_phandle_with_args_map(np, "phandle-list",
+					    "phandle-missing", 0, &args);
+	unittest(rc == -EINVAL, "expected:%i got:%i\n", -EINVAL, rc);
+
+	/* Check for bad phandle in list */
+	rc = of_parse_phandle_with_args_map(np, "phandle-list-bad-phandle",
+					    "phandle", 0, &args);
+	unittest(rc == -EINVAL, "expected:%i got:%i\n", -EINVAL, rc);
+
+	/* Check for incorrectly formed argument list */
+	rc = of_parse_phandle_with_args_map(np, "phandle-list-bad-args",
+					    "phandle", 1, &args);
+	unittest(rc == -EINVAL, "expected:%i got:%i\n", -EINVAL, rc);
+}
+
+static void __init of_unittest_property_string(void)
+{
+	const char *strings[4];
+	struct device_node *np;
+	int rc;
+
+	np = of_find_node_by_path("/testcase-data/phandle-tests/consumer-a");
+	if (!np) {
+		pr_err("No testcase data in device tree\n");
+		return;
+	}
+
+	rc = of_property_match_string(np, "phandle-list-names", "first");
+	unittest(rc == 0, "first expected:0 got:%i\n", rc);
+	rc = of_property_match_string(np, "phandle-list-names", "second");
+	unittest(rc == 1, "second expected:1 got:%i\n", rc);
+	rc = of_property_match_string(np, "phandle-list-names", "third");
+	unittest(rc == 2, "third expected:2 got:%i\n", rc);
+	rc = of_property_match_string(np, "phandle-list-names", "fourth");
+	unittest(rc == -ENODATA, "unmatched string; rc=%i\n", rc);
+	rc = of_property_match_string(np, "missing-property", "blah");
+	unittest(rc == -EINVAL, "missing property; rc=%i\n", rc);
+	rc = of_property_match_string(np, "empty-property", "blah");
+	unittest(rc == -ENODATA, "empty property; rc=%i\n", rc);
+	rc = of_property_match_string(np, "unterminated-string", "blah");
+	unittest(rc == -EILSEQ, "unterminated string; rc=%i\n", rc);
+
+	/* of_property_count_strings() tests */
+	rc = of_property_count_strings(np, "string-property");
+	unittest(rc == 1, "Incorrect string count; rc=%i\n", rc);
+	rc = of_property_count_strings(np, "phandle-list-names");
+	unittest(rc == 3, "Incorrect string count; rc=%i\n", rc);
+	rc = of_property_count_strings(np, "unterminated-string");
+	unittest(rc == -EILSEQ, "unterminated string; rc=%i\n", rc);
+	rc = of_property_count_strings(np, "unterminated-string-list");
+	unittest(rc == -EILSEQ, "unterminated string array; rc=%i\n", rc);
+
+	/* of_property_read_string_index() tests */
+	rc = of_property_read_string_index(np, "string-property", 0, strings);
+	unittest(rc == 0 && !strcmp(strings[0], "foobar"), "of_property_read_string_index() failure; rc=%i\n", rc);
+	strings[0] = NULL;
+	rc = of_property_read_string_index(np, "string-property", 1, strings);
+	unittest(rc == -ENODATA && strings[0] == NULL, "of_property_read_string_index() failure; rc=%i\n", rc);
+	rc = of_property_read_string_index(np, "phandle-list-names", 0, strings);
+	unittest(rc == 0 && !strcmp(strings[0], "first"), "of_property_read_string_index() failure; rc=%i\n", rc);
+	rc = of_property_read_string_index(np, "phandle-list-names", 1, strings);
+	unittest(rc == 0 && !strcmp(strings[0], "second"), "of_property_read_string_index() failure; rc=%i\n", rc);
+	rc = of_property_read_string_index(np, "phandle-list-names", 2, strings);
+	unittest(rc == 0 && !strcmp(strings[0], "third"), "of_property_read_string_index() failure; rc=%i\n", rc);
+	strings[0] = NULL;
+	rc = of_property_read_string_index(np, "phandle-list-names", 3, strings);
+	unittest(rc == -ENODATA && strings[0] == NULL, "of_property_read_string_index() failure; rc=%i\n", rc);
+	strings[0] = NULL;
+	rc = of_property_read_string_index(np, "unterminated-string", 0, strings);
+	unittest(rc == -EILSEQ && strings[0] == NULL, "of_property_read_string_index() failure; rc=%i\n", rc);
+	rc = of_property_read_string_index(np, "unterminated-string-list", 0, strings);
+	unittest(rc == 0 && !strcmp(strings[0], "first"), "of_property_read_string_index() failure; rc=%i\n", rc);
+	strings[0] = NULL;
+	rc = of_property_read_string_index(np, "unterminated-string-list", 2, strings); /* should fail */
+	unittest(rc == -EILSEQ && strings[0] == NULL, "of_property_read_string_index() failure; rc=%i\n", rc);
+	strings[1] = NULL;
+
+	/* of_property_read_string_array() tests */
+	rc = of_property_read_string_array(np, "string-property", strings, 4);
+	unittest(rc == 1, "Incorrect string count; rc=%i\n", rc);
+	rc = of_property_read_string_array(np, "phandle-list-names", strings, 4);
+	unittest(rc == 3, "Incorrect string count; rc=%i\n", rc);
+	rc = of_property_read_string_array(np, "unterminated-string", strings, 4);
+	unittest(rc == -EILSEQ, "unterminated string; rc=%i\n", rc);
+	/* -- An incorrectly formed string should cause a failure */
+	rc = of_property_read_string_array(np, "unterminated-string-list", strings, 4);
+	unittest(rc == -EILSEQ, "unterminated string array; rc=%i\n", rc);
+	/* -- parsing the correctly formed strings should still work: */
+	strings[2] = NULL;
+	rc = of_property_read_string_array(np, "unterminated-string-list", strings, 2);
+	unittest(rc == 2 && strings[2] == NULL, "of_property_read_string_array() failure; rc=%i\n", rc);
+	strings[1] = NULL;
+	rc = of_property_read_string_array(np, "phandle-list-names", strings, 1);
+	unittest(rc == 1 && strings[1] == NULL, "Overwrote end of string array; rc=%i, str='%s'\n", rc, strings[1]);
+}
+
+#define propcmp(p1, p2) (((p1)->length == (p2)->length) && \
+			(p1)->value && (p2)->value && \
+			!memcmp((p1)->value, (p2)->value, (p1)->length) && \
+			!strcmp((p1)->name, (p2)->name))
+static void __init of_unittest_property_copy(void)
+{
+#ifdef CONFIG_OF_DYNAMIC
+	struct property p1 = { .name = "p1", .length = 0, .value = "" };
+	struct property p2 = { .name = "p2", .length = 5, .value = "abcd" };
+	struct property *new;
+
+	new = __of_prop_dup(&p1, GFP_KERNEL);
+	unittest(new && propcmp(&p1, new), "empty property didn't copy correctly\n");
+	kfree(new->value);
+	kfree(new->name);
+	kfree(new);
+
+	new = __of_prop_dup(&p2, GFP_KERNEL);
+	unittest(new && propcmp(&p2, new), "non-empty property didn't copy correctly\n");
+	kfree(new->value);
+	kfree(new->name);
+	kfree(new);
+#endif
+}
+
+static void __init of_unittest_changeset(void)
+{
+#ifdef CONFIG_OF_DYNAMIC
+	struct property *ppadd, padd = { .name = "prop-add", .length = 1, .value = "" };
+	struct property *ppname_n1,  pname_n1  = { .name = "name", .length = 3, .value = "n1"  };
+	struct property *ppname_n2,  pname_n2  = { .name = "name", .length = 3, .value = "n2"  };
+	struct property *ppname_n21, pname_n21 = { .name = "name", .length = 3, .value = "n21" };
+	struct property *ppupdate, pupdate = { .name = "prop-update", .length = 5, .value = "abcd" };
+	struct property *ppremove;
+	struct device_node *n1, *n2, *n21, *nchangeset, *nremove, *parent, *np;
+	struct of_changeset chgset;
+
+	n1 = __of_node_dup(NULL, "n1");
+	unittest(n1, "testcase setup failure\n");
+
+	n2 = __of_node_dup(NULL, "n2");
+	unittest(n2, "testcase setup failure\n");
+
+	n21 = __of_node_dup(NULL, "n21");
+	unittest(n21, "testcase setup failure %p\n", n21);
+
+	nchangeset = of_find_node_by_path("/testcase-data/changeset");
+	nremove = of_get_child_by_name(nchangeset, "node-remove");
+	unittest(nremove, "testcase setup failure\n");
+
+	ppadd = __of_prop_dup(&padd, GFP_KERNEL);
+	unittest(ppadd, "testcase setup failure\n");
+
+	ppname_n1  = __of_prop_dup(&pname_n1, GFP_KERNEL);
+	unittest(ppname_n1, "testcase setup failure\n");
+
+	ppname_n2  = __of_prop_dup(&pname_n2, GFP_KERNEL);
+	unittest(ppname_n2, "testcase setup failure\n");
+
+	ppname_n21 = __of_prop_dup(&pname_n21, GFP_KERNEL);
+	unittest(ppname_n21, "testcase setup failure\n");
+
+	ppupdate = __of_prop_dup(&pupdate, GFP_KERNEL);
+	unittest(ppupdate, "testcase setup failure\n");
+
+	parent = nchangeset;
+	n1->parent = parent;
+	n2->parent = parent;
+	n21->parent = n2;
+
+	ppremove = of_find_property(parent, "prop-remove", NULL);
+	unittest(ppremove, "failed to find removal prop");
+
+	of_changeset_init(&chgset);
+
+	unittest(!of_changeset_attach_node(&chgset, n1), "fail attach n1\n");
+	unittest(!of_changeset_add_property(&chgset, n1, ppname_n1), "fail add prop name\n");
+
+	unittest(!of_changeset_attach_node(&chgset, n2), "fail attach n2\n");
+	unittest(!of_changeset_add_property(&chgset, n2, ppname_n2), "fail add prop name\n");
+
+	unittest(!of_changeset_detach_node(&chgset, nremove), "fail remove node\n");
+	unittest(!of_changeset_add_property(&chgset, n21, ppname_n21), "fail add prop name\n");
+
+	unittest(!of_changeset_attach_node(&chgset, n21), "fail attach n21\n");
+
+	unittest(!of_changeset_add_property(&chgset, parent, ppadd), "fail add prop prop-add\n");
+	unittest(!of_changeset_update_property(&chgset, parent, ppupdate), "fail update prop\n");
+	unittest(!of_changeset_remove_property(&chgset, parent, ppremove), "fail remove prop\n");
+
+	unittest(!of_changeset_apply(&chgset), "apply failed\n");
+
+	of_node_put(nchangeset);
+
+	/* Make sure node names are constructed correctly */
+	unittest((np = of_find_node_by_path("/testcase-data/changeset/n2/n21")),
+		 "'%pOF' not added\n", n21);
+	of_node_put(np);
+
+	unittest(!of_changeset_revert(&chgset), "revert failed\n");
+
+	of_changeset_destroy(&chgset);
+#endif
+}
+
+static void __init of_unittest_parse_interrupts(void)
+{
+	struct device_node *np;
+	struct of_phandle_args args;
+	int i, rc;
+
+	if (of_irq_workarounds & OF_IMAP_OLDWORLD_MAC)
+		return;
+
+	np = of_find_node_by_path("/testcase-data/interrupts/interrupts0");
+	if (!np) {
+		pr_err("missing testcase data\n");
+		return;
+	}
+
+	for (i = 0; i < 4; i++) {
+		bool passed = true;
+
+		args.args_count = 0;
+		rc = of_irq_parse_one(np, i, &args);
+
+		passed &= !rc;
+		passed &= (args.args_count == 1);
+		passed &= (args.args[0] == (i + 1));
+
+		unittest(passed, "index %i - data error on node %pOF rc=%i\n",
+			 i, args.np, rc);
+	}
+	of_node_put(np);
+
+	np = of_find_node_by_path("/testcase-data/interrupts/interrupts1");
+	if (!np) {
+		pr_err("missing testcase data\n");
+		return;
+	}
+
+	for (i = 0; i < 4; i++) {
+		bool passed = true;
+
+		args.args_count = 0;
+		rc = of_irq_parse_one(np, i, &args);
+
+		/* Test the values from tests-phandle.dtsi */
+		switch (i) {
+		case 0:
+			passed &= !rc;
+			passed &= (args.args_count == 1);
+			passed &= (args.args[0] == 9);
+			break;
+		case 1:
+			passed &= !rc;
+			passed &= (args.args_count == 3);
+			passed &= (args.args[0] == 10);
+			passed &= (args.args[1] == 11);
+			passed &= (args.args[2] == 12);
+			break;
+		case 2:
+			passed &= !rc;
+			passed &= (args.args_count == 2);
+			passed &= (args.args[0] == 13);
+			passed &= (args.args[1] == 14);
+			break;
+		case 3:
+			passed &= !rc;
+			passed &= (args.args_count == 2);
+			passed &= (args.args[0] == 15);
+			passed &= (args.args[1] == 16);
+			break;
+		default:
+			passed = false;
+		}
+		unittest(passed, "index %i - data error on node %pOF rc=%i\n",
+			 i, args.np, rc);
+	}
+	of_node_put(np);
+}
+
+static void __init of_unittest_parse_interrupts_extended(void)
+{
+	struct device_node *np;
+	struct of_phandle_args args;
+	int i, rc;
+
+	if (of_irq_workarounds & OF_IMAP_OLDWORLD_MAC)
+		return;
+
+	np = of_find_node_by_path("/testcase-data/interrupts/interrupts-extended0");
+	if (!np) {
+		pr_err("missing testcase data\n");
+		return;
+	}
+
+	for (i = 0; i < 7; i++) {
+		bool passed = true;
+
+		rc = of_irq_parse_one(np, i, &args);
+
+		/* Test the values from tests-phandle.dtsi */
+		switch (i) {
+		case 0:
+			passed &= !rc;
+			passed &= (args.args_count == 1);
+			passed &= (args.args[0] == 1);
+			break;
+		case 1:
+			passed &= !rc;
+			passed &= (args.args_count == 3);
+			passed &= (args.args[0] == 2);
+			passed &= (args.args[1] == 3);
+			passed &= (args.args[2] == 4);
+			break;
+		case 2:
+			passed &= !rc;
+			passed &= (args.args_count == 2);
+			passed &= (args.args[0] == 5);
+			passed &= (args.args[1] == 6);
+			break;
+		case 3:
+			passed &= !rc;
+			passed &= (args.args_count == 1);
+			passed &= (args.args[0] == 9);
+			break;
+		case 4:
+			passed &= !rc;
+			passed &= (args.args_count == 3);
+			passed &= (args.args[0] == 10);
+			passed &= (args.args[1] == 11);
+			passed &= (args.args[2] == 12);
+			break;
+		case 5:
+			passed &= !rc;
+			passed &= (args.args_count == 2);
+			passed &= (args.args[0] == 13);
+			passed &= (args.args[1] == 14);
+			break;
+		case 6:
+			passed &= !rc;
+			passed &= (args.args_count == 1);
+			passed &= (args.args[0] == 15);
+			break;
+		default:
+			passed = false;
+		}
+
+		unittest(passed, "index %i - data error on node %pOF rc=%i\n",
+			 i, args.np, rc);
+	}
+	of_node_put(np);
+}
+
+static const struct of_device_id match_node_table[] = {
+	{ .data = "A", .name = "name0", }, /* Name alone is lowest priority */
+	{ .data = "B", .type = "type1", }, /* followed by type alone */
+
+	{ .data = "Ca", .name = "name2", .type = "type1", }, /* followed by both together */
+	{ .data = "Cb", .name = "name2", }, /* Only match when type doesn't match */
+	{ .data = "Cc", .name = "name2", .type = "type2", },
+
+	{ .data = "E", .compatible = "compat3" },
+	{ .data = "G", .compatible = "compat2", },
+	{ .data = "H", .compatible = "compat2", .name = "name5", },
+	{ .data = "I", .compatible = "compat2", .type = "type1", },
+	{ .data = "J", .compatible = "compat2", .type = "type1", .name = "name8", },
+	{ .data = "K", .compatible = "compat2", .name = "name9", },
+	{}
+};
+
+static struct {
+	const char *path;
+	const char *data;
+} match_node_tests[] = {
+	{ .path = "/testcase-data/match-node/name0", .data = "A", },
+	{ .path = "/testcase-data/match-node/name1", .data = "B", },
+	{ .path = "/testcase-data/match-node/a/name2", .data = "Ca", },
+	{ .path = "/testcase-data/match-node/b/name2", .data = "Cb", },
+	{ .path = "/testcase-data/match-node/c/name2", .data = "Cc", },
+	{ .path = "/testcase-data/match-node/name3", .data = "E", },
+	{ .path = "/testcase-data/match-node/name4", .data = "G", },
+	{ .path = "/testcase-data/match-node/name5", .data = "H", },
+	{ .path = "/testcase-data/match-node/name6", .data = "G", },
+	{ .path = "/testcase-data/match-node/name7", .data = "I", },
+	{ .path = "/testcase-data/match-node/name8", .data = "J", },
+	{ .path = "/testcase-data/match-node/name9", .data = "K", },
+};
+
+static void __init of_unittest_match_node(void)
+{
+	struct device_node *np;
+	const struct of_device_id *match;
+	int i;
+
+	for (i = 0; i < ARRAY_SIZE(match_node_tests); i++) {
+		np = of_find_node_by_path(match_node_tests[i].path);
+		if (!np) {
+			unittest(0, "missing testcase node %s\n",
+				match_node_tests[i].path);
+			continue;
+		}
+
+		match = of_match_node(match_node_table, np);
+		if (!match) {
+			unittest(0, "%s didn't match anything\n",
+				match_node_tests[i].path);
+			continue;
+		}
+
+		if (strcmp(match->data, match_node_tests[i].data) != 0) {
+			unittest(0, "%s got wrong match. expected %s, got %s\n",
+				match_node_tests[i].path, match_node_tests[i].data,
+				(const char *)match->data);
+			continue;
+		}
+		unittest(1, "passed");
+	}
+}
+
+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",
+};
+static void __init of_unittest_platform_populate(void)
+{
+	int irq, rc;
+	struct device_node *np, *child, *grandchild;
+	struct platform_device *pdev, *test_bus;
+	const struct of_device_id match[] = {
+		{ .compatible = "test-device", },
+		{}
+	};
+
+	np = of_find_node_by_path("/testcase-data");
+	of_platform_default_populate(np, NULL, NULL);
+
+	/* Test that a missing irq domain returns -EPROBE_DEFER */
+	np = of_find_node_by_path("/testcase-data/testcase-device1");
+	pdev = of_find_device_by_node(np);
+	unittest(pdev, "device 1 creation failed\n");
+
+	if (!(of_irq_workarounds & OF_IMAP_OLDWORLD_MAC)) {
+		irq = platform_get_irq(pdev, 0);
+		unittest(irq == -EPROBE_DEFER,
+			 "device deferred probe failed - %d\n", irq);
+
+		/* Test that a parsing failure does not return -EPROBE_DEFER */
+		np = of_find_node_by_path("/testcase-data/testcase-device2");
+		pdev = of_find_device_by_node(np);
+		unittest(pdev, "device 2 creation failed\n");
+		irq = platform_get_irq(pdev, 0);
+		unittest(irq < 0 && irq != -EPROBE_DEFER,
+			 "device parsing error failed - %d\n", irq);
+	}
+
+	np = of_find_node_by_path("/testcase-data/platform-tests");
+	unittest(np, "No testcase data in device tree\n");
+	if (!np)
+		return;
+
+	test_bus = platform_device_register_full(&test_bus_info);
+	rc = PTR_ERR_OR_ZERO(test_bus);
+	unittest(!rc, "testbus registration failed; rc=%i\n", rc);
+	if (rc)
+		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)
+			unittest(of_find_device_by_node(grandchild),
+				 "Could not create device for node '%s'\n",
+				 grandchild->name);
+	}
+
+	of_platform_depopulate(&test_bus->dev);
+	for_each_child_of_node(np, child) {
+		for_each_child_of_node(child, grandchild)
+			unittest(!of_find_device_by_node(grandchild),
+				 "device didn't get destroyed '%s'\n",
+				 grandchild->name);
+	}
+
+	platform_device_unregister(test_bus);
+	of_node_put(np);
+}
+
+/**
+ *	update_node_properties - adds the properties
+ *	of np into dup node (present in live tree) and
+ *	updates parent of children of np to dup.
+ *
+ *	@np:	node already present in live tree
+ *	@dup:	node present in live tree to be updated
+ */
+static void update_node_properties(struct device_node *np,
+					struct device_node *dup)
+{
+	struct property *prop;
+	struct device_node *child;
+
+	for_each_property_of_node(np, prop)
+		of_add_property(dup, prop);
+
+	for_each_child_of_node(np, child)
+		child->parent = dup;
+}
+
+/**
+ *	attach_node_and_children - attaches nodes
+ *	and its children to live tree
+ *
+ *	@np:	Node to attach to live tree
+ */
+static int attach_node_and_children(struct device_node *np)
+{
+	struct device_node *next, *dup, *child;
+	unsigned long flags;
+	const char *full_name;
+
+	full_name = kasprintf(GFP_KERNEL, "%pOF", np);
+	dup = of_find_node_by_path(full_name);
+	kfree(full_name);
+	if (dup) {
+		update_node_properties(np, dup);
+		return 0;
+	}
+
+	child = np->child;
+	np->child = NULL;
+
+	mutex_lock(&of_mutex);
+	raw_spin_lock_irqsave(&devtree_lock, flags);
+	np->sibling = np->parent->child;
+	np->parent->child = np;
+	of_node_clear_flag(np, OF_DETACHED);
+	raw_spin_unlock_irqrestore(&devtree_lock, flags);
+
+	__of_attach_node_sysfs(np);
+	mutex_unlock(&of_mutex);
+
+	while (child) {
+		next = child->sibling;
+		attach_node_and_children(child);
+		child = next;
+	}
+
+	return 0;
+}
+
+/**
+ *	unittest_data_add - Reads, copies data from
+ *	linked tree and attaches it to the live tree
+ */
+static int __init unittest_data_add(void)
+{
+	void *unittest_data;
+	struct device_node *unittest_data_node, *np;
+	/*
+	 * __dtb_testcases_begin[] and __dtb_testcases_end[] are magically
+	 * created by cmd_dt_S_dtb in scripts/Makefile.lib
+	 */
+	extern uint8_t __dtb_testcases_begin[];
+	extern uint8_t __dtb_testcases_end[];
+	const int size = __dtb_testcases_end - __dtb_testcases_begin;
+	int rc;
+
+	if (!size) {
+		pr_warn("%s: No testcase data to attach; not running tests\n",
+			__func__);
+		return -ENODATA;
+	}
+
+	/* creating copy */
+	unittest_data = kmemdup(__dtb_testcases_begin, size, GFP_KERNEL);
+
+	if (!unittest_data) {
+		pr_warn("%s: Failed to allocate memory for unittest_data; "
+			"not running tests\n", __func__);
+		return -ENOMEM;
+	}
+	of_fdt_unflatten_tree(unittest_data, NULL, &unittest_data_node);
+	if (!unittest_data_node) {
+		pr_warn("%s: No tree to attach; not running tests\n", __func__);
+		return -ENODATA;
+	}
+
+	/*
+	 * This lock normally encloses of_resolve_phandles()
+	 */
+	of_overlay_mutex_lock();
+
+	rc = of_resolve_phandles(unittest_data_node);
+	if (rc) {
+		pr_err("%s: Failed to resolve phandles (rc=%i)\n", __func__, rc);
+		of_overlay_mutex_unlock();
+		return -EINVAL;
+	}
+
+	if (!of_root) {
+		of_root = unittest_data_node;
+		for_each_of_allnodes(np)
+			__of_attach_node_sysfs(np);
+		of_aliases = of_find_node_by_path("/aliases");
+		of_chosen = of_find_node_by_path("/chosen");
+		of_overlay_mutex_unlock();
+		return 0;
+	}
+
+	/* attach the sub-tree to live tree */
+	np = unittest_data_node->child;
+	while (np) {
+		struct device_node *next = np->sibling;
+
+		np->parent = of_root;
+		attach_node_and_children(np);
+		np = next;
+	}
+
+	of_overlay_mutex_unlock();
+
+	return 0;
+}
+
+#ifdef CONFIG_OF_OVERLAY
+static int __init overlay_data_apply(const char *overlay_name, int *overlay_id);
+
+static int unittest_probe(struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+	struct device_node *np = dev->of_node;
+
+	if (np == NULL) {
+		dev_err(dev, "No OF data for device\n");
+		return -EINVAL;
+
+	}
+
+	dev_dbg(dev, "%s for node @%pOF\n", __func__, np);
+
+	of_platform_populate(np, NULL, NULL, &pdev->dev);
+
+	return 0;
+}
+
+static int unittest_remove(struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+	struct device_node *np = dev->of_node;
+
+	dev_dbg(dev, "%s for node @%pOF\n", __func__, np);
+	return 0;
+}
+
+static const struct of_device_id unittest_match[] = {
+	{ .compatible = "unittest", },
+	{},
+};
+
+static struct platform_driver unittest_driver = {
+	.probe			= unittest_probe,
+	.remove			= unittest_remove,
+	.driver = {
+		.name		= "unittest",
+		.of_match_table	= of_match_ptr(unittest_match),
+	},
+};
+
+/* get the platform device instantiated at the path */
+static struct platform_device *of_path_to_platform_device(const char *path)
+{
+	struct device_node *np;
+	struct platform_device *pdev;
+
+	np = of_find_node_by_path(path);
+	if (np == NULL)
+		return NULL;
+
+	pdev = of_find_device_by_node(np);
+	of_node_put(np);
+
+	return pdev;
+}
+
+/* find out if a platform device exists at that path */
+static int of_path_platform_device_exists(const char *path)
+{
+	struct platform_device *pdev;
+
+	pdev = of_path_to_platform_device(path);
+	platform_device_put(pdev);
+	return pdev != NULL;
+}
+
+#if IS_BUILTIN(CONFIG_I2C)
+
+/* get the i2c client device instantiated at the path */
+static struct i2c_client *of_path_to_i2c_client(const char *path)
+{
+	struct device_node *np;
+	struct i2c_client *client;
+
+	np = of_find_node_by_path(path);
+	if (np == NULL)
+		return NULL;
+
+	client = of_find_i2c_device_by_node(np);
+	of_node_put(np);
+
+	return client;
+}
+
+/* find out if a i2c client device exists at that path */
+static int of_path_i2c_client_exists(const char *path)
+{
+	struct i2c_client *client;
+
+	client = of_path_to_i2c_client(path);
+	if (client)
+		put_device(&client->dev);
+	return client != NULL;
+}
+#else
+static int of_path_i2c_client_exists(const char *path)
+{
+	return 0;
+}
+#endif
+
+enum overlay_type {
+	PDEV_OVERLAY,
+	I2C_OVERLAY
+};
+
+static int of_path_device_type_exists(const char *path,
+		enum overlay_type ovtype)
+{
+	switch (ovtype) {
+	case PDEV_OVERLAY:
+		return of_path_platform_device_exists(path);
+	case I2C_OVERLAY:
+		return of_path_i2c_client_exists(path);
+	}
+	return 0;
+}
+
+static const char *unittest_path(int nr, enum overlay_type ovtype)
+{
+	const char *base;
+	static char buf[256];
+
+	switch (ovtype) {
+	case PDEV_OVERLAY:
+		base = "/testcase-data/overlay-node/test-bus";
+		break;
+	case I2C_OVERLAY:
+		base = "/testcase-data/overlay-node/test-bus/i2c-test-bus";
+		break;
+	default:
+		buf[0] = '\0';
+		return buf;
+	}
+	snprintf(buf, sizeof(buf) - 1, "%s/test-unittest%d", base, nr);
+	buf[sizeof(buf) - 1] = '\0';
+	return buf;
+}
+
+static int of_unittest_device_exists(int unittest_nr, enum overlay_type ovtype)
+{
+	const char *path;
+
+	path = unittest_path(unittest_nr, ovtype);
+
+	switch (ovtype) {
+	case PDEV_OVERLAY:
+		return of_path_platform_device_exists(path);
+	case I2C_OVERLAY:
+		return of_path_i2c_client_exists(path);
+	}
+	return 0;
+}
+
+static const char *overlay_name_from_nr(int nr)
+{
+	static char buf[256];
+
+	snprintf(buf, sizeof(buf) - 1,
+		"overlay_%d", nr);
+	buf[sizeof(buf) - 1] = '\0';
+
+	return buf;
+}
+
+static const char *bus_path = "/testcase-data/overlay-node/test-bus";
+
+/* it is guaranteed that overlay ids are assigned in sequence */
+#define MAX_UNITTEST_OVERLAYS	256
+static unsigned long overlay_id_bits[BITS_TO_LONGS(MAX_UNITTEST_OVERLAYS)];
+static int overlay_first_id = -1;
+
+static void of_unittest_track_overlay(int id)
+{
+	if (overlay_first_id < 0)
+		overlay_first_id = id;
+	id -= overlay_first_id;
+
+	/* we shouldn't need that many */
+	BUG_ON(id >= MAX_UNITTEST_OVERLAYS);
+	overlay_id_bits[BIT_WORD(id)] |= BIT_MASK(id);
+}
+
+static void of_unittest_untrack_overlay(int id)
+{
+	if (overlay_first_id < 0)
+		return;
+	id -= overlay_first_id;
+	BUG_ON(id >= MAX_UNITTEST_OVERLAYS);
+	overlay_id_bits[BIT_WORD(id)] &= ~BIT_MASK(id);
+}
+
+static void of_unittest_destroy_tracked_overlays(void)
+{
+	int id, ret, defers, ovcs_id;
+
+	if (overlay_first_id < 0)
+		return;
+
+	/* try until no defers */
+	do {
+		defers = 0;
+		/* remove in reverse order */
+		for (id = MAX_UNITTEST_OVERLAYS - 1; id >= 0; id--) {
+			if (!(overlay_id_bits[BIT_WORD(id)] & BIT_MASK(id)))
+				continue;
+
+			ovcs_id = id + overlay_first_id;
+			ret = of_overlay_remove(&ovcs_id);
+			if (ret == -ENODEV) {
+				pr_warn("%s: no overlay to destroy for #%d\n",
+					__func__, id + overlay_first_id);
+				continue;
+			}
+			if (ret != 0) {
+				defers++;
+				pr_warn("%s: overlay destroy failed for #%d\n",
+					__func__, id + overlay_first_id);
+				continue;
+			}
+
+			overlay_id_bits[BIT_WORD(id)] &= ~BIT_MASK(id);
+		}
+	} while (defers > 0);
+}
+
+static int __init of_unittest_apply_overlay(int overlay_nr, int unittest_nr,
+		int *overlay_id)
+{
+	const char *overlay_name;
+
+	overlay_name = overlay_name_from_nr(overlay_nr);
+
+	if (!overlay_data_apply(overlay_name, overlay_id)) {
+		unittest(0, "could not apply overlay \"%s\"\n",
+				overlay_name);
+		return -EFAULT;
+	}
+	of_unittest_track_overlay(*overlay_id);
+
+	return 0;
+}
+
+/* apply an overlay while checking before and after states */
+static int __init of_unittest_apply_overlay_check(int overlay_nr,
+		int unittest_nr, int before, int after,
+		enum overlay_type ovtype)
+{
+	int ret, ovcs_id;
+
+	/* unittest device must not be in before state */
+	if (of_unittest_device_exists(unittest_nr, ovtype) != before) {
+		unittest(0, "%s with device @\"%s\" %s\n",
+				overlay_name_from_nr(overlay_nr),
+				unittest_path(unittest_nr, ovtype),
+				!before ? "enabled" : "disabled");
+		return -EINVAL;
+	}
+
+	ovcs_id = 0;
+	ret = of_unittest_apply_overlay(overlay_nr, unittest_nr, &ovcs_id);
+	if (ret != 0) {
+		/* of_unittest_apply_overlay already called unittest() */
+		return ret;
+	}
+
+	/* unittest device must be to set to after state */
+	if (of_unittest_device_exists(unittest_nr, ovtype) != after) {
+		unittest(0, "%s failed to create @\"%s\" %s\n",
+				overlay_name_from_nr(overlay_nr),
+				unittest_path(unittest_nr, ovtype),
+				!after ? "enabled" : "disabled");
+		return -EINVAL;
+	}
+
+	return 0;
+}
+
+/* apply an overlay and then revert it while checking before, after states */
+static int __init of_unittest_apply_revert_overlay_check(int overlay_nr,
+		int unittest_nr, int before, int after,
+		enum overlay_type ovtype)
+{
+	int ret, ovcs_id;
+
+	/* unittest device must be in before state */
+	if (of_unittest_device_exists(unittest_nr, ovtype) != before) {
+		unittest(0, "%s with device @\"%s\" %s\n",
+				overlay_name_from_nr(overlay_nr),
+				unittest_path(unittest_nr, ovtype),
+				!before ? "enabled" : "disabled");
+		return -EINVAL;
+	}
+
+	/* apply the overlay */
+	ovcs_id = 0;
+	ret = of_unittest_apply_overlay(overlay_nr, unittest_nr, &ovcs_id);
+	if (ret != 0) {
+		/* of_unittest_apply_overlay already called unittest() */
+		return ret;
+	}
+
+	/* unittest device must be in after state */
+	if (of_unittest_device_exists(unittest_nr, ovtype) != after) {
+		unittest(0, "%s failed to create @\"%s\" %s\n",
+				overlay_name_from_nr(overlay_nr),
+				unittest_path(unittest_nr, ovtype),
+				!after ? "enabled" : "disabled");
+		return -EINVAL;
+	}
+
+	ret = of_overlay_remove(&ovcs_id);
+	if (ret != 0) {
+		unittest(0, "%s failed to be destroyed @\"%s\"\n",
+				overlay_name_from_nr(overlay_nr),
+				unittest_path(unittest_nr, ovtype));
+		return ret;
+	}
+
+	/* unittest device must be again in before state */
+	if (of_unittest_device_exists(unittest_nr, PDEV_OVERLAY) != before) {
+		unittest(0, "%s with device @\"%s\" %s\n",
+				overlay_name_from_nr(overlay_nr),
+				unittest_path(unittest_nr, ovtype),
+				!before ? "enabled" : "disabled");
+		return -EINVAL;
+	}
+
+	return 0;
+}
+
+/* test activation of device */
+static void __init of_unittest_overlay_0(void)
+{
+	/* device should enable */
+	if (of_unittest_apply_overlay_check(0, 0, 0, 1, PDEV_OVERLAY))
+		return;
+
+	unittest(1, "overlay test %d passed\n", 0);
+}
+
+/* test deactivation of device */
+static void __init of_unittest_overlay_1(void)
+{
+	/* device should disable */
+	if (of_unittest_apply_overlay_check(1, 1, 1, 0, PDEV_OVERLAY))
+		return;
+
+	unittest(1, "overlay test %d passed\n", 1);
+}
+
+/* test activation of device */
+static void __init of_unittest_overlay_2(void)
+{
+	/* device should enable */
+	if (of_unittest_apply_overlay_check(2, 2, 0, 1, PDEV_OVERLAY))
+		return;
+
+	unittest(1, "overlay test %d passed\n", 2);
+}
+
+/* test deactivation of device */
+static void __init of_unittest_overlay_3(void)
+{
+	/* device should disable */
+	if (of_unittest_apply_overlay_check(3, 3, 1, 0, PDEV_OVERLAY))
+		return;
+
+	unittest(1, "overlay test %d passed\n", 3);
+}
+
+/* test activation of a full device node */
+static void __init of_unittest_overlay_4(void)
+{
+	/* device should disable */
+	if (of_unittest_apply_overlay_check(4, 4, 0, 1, PDEV_OVERLAY))
+		return;
+
+	unittest(1, "overlay test %d passed\n", 4);
+}
+
+/* test overlay apply/revert sequence */
+static void __init of_unittest_overlay_5(void)
+{
+	/* device should disable */
+	if (of_unittest_apply_revert_overlay_check(5, 5, 0, 1, PDEV_OVERLAY))
+		return;
+
+	unittest(1, "overlay test %d passed\n", 5);
+}
+
+/* test overlay application in sequence */
+static void __init of_unittest_overlay_6(void)
+{
+	int i, ov_id[2], ovcs_id;
+	int overlay_nr = 6, unittest_nr = 6;
+	int before = 0, after = 1;
+	const char *overlay_name;
+
+	/* unittest device must be in before state */
+	for (i = 0; i < 2; i++) {
+		if (of_unittest_device_exists(unittest_nr + i, PDEV_OVERLAY)
+				!= before) {
+			unittest(0, "%s with device @\"%s\" %s\n",
+					overlay_name_from_nr(overlay_nr + i),
+					unittest_path(unittest_nr + i,
+						PDEV_OVERLAY),
+					!before ? "enabled" : "disabled");
+			return;
+		}
+	}
+
+	/* apply the overlays */
+	for (i = 0; i < 2; i++) {
+
+		overlay_name = overlay_name_from_nr(overlay_nr + i);
+
+		if (!overlay_data_apply(overlay_name, &ovcs_id)) {
+			unittest(0, "could not apply overlay \"%s\"\n",
+					overlay_name);
+			return;
+		}
+		ov_id[i] = ovcs_id;
+		of_unittest_track_overlay(ov_id[i]);
+	}
+
+	for (i = 0; i < 2; i++) {
+		/* unittest device must be in after state */
+		if (of_unittest_device_exists(unittest_nr + i, PDEV_OVERLAY)
+				!= after) {
+			unittest(0, "overlay @\"%s\" failed @\"%s\" %s\n",
+					overlay_name_from_nr(overlay_nr + i),
+					unittest_path(unittest_nr + i,
+						PDEV_OVERLAY),
+					!after ? "enabled" : "disabled");
+			return;
+		}
+	}
+
+	for (i = 1; i >= 0; i--) {
+		ovcs_id = ov_id[i];
+		if (of_overlay_remove(&ovcs_id)) {
+			unittest(0, "%s failed destroy @\"%s\"\n",
+					overlay_name_from_nr(overlay_nr + i),
+					unittest_path(unittest_nr + i,
+						PDEV_OVERLAY));
+			return;
+		}
+		of_unittest_untrack_overlay(ov_id[i]);
+	}
+
+	for (i = 0; i < 2; i++) {
+		/* unittest device must be again in before state */
+		if (of_unittest_device_exists(unittest_nr + i, PDEV_OVERLAY)
+				!= before) {
+			unittest(0, "%s with device @\"%s\" %s\n",
+					overlay_name_from_nr(overlay_nr + i),
+					unittest_path(unittest_nr + i,
+						PDEV_OVERLAY),
+					!before ? "enabled" : "disabled");
+			return;
+		}
+	}
+
+	unittest(1, "overlay test %d passed\n", 6);
+}
+
+/* test overlay application in sequence */
+static void __init of_unittest_overlay_8(void)
+{
+	int i, ov_id[2], ovcs_id;
+	int overlay_nr = 8, unittest_nr = 8;
+	const char *overlay_name;
+
+	/* we don't care about device state in this test */
+
+	/* apply the overlays */
+	for (i = 0; i < 2; i++) {
+
+		overlay_name = overlay_name_from_nr(overlay_nr + i);
+
+		if (!overlay_data_apply(overlay_name, &ovcs_id)) {
+			unittest(0, "could not apply overlay \"%s\"\n",
+					overlay_name);
+			return;
+		}
+		ov_id[i] = ovcs_id;
+		of_unittest_track_overlay(ov_id[i]);
+	}
+
+	/* now try to remove first overlay (it should fail) */
+	ovcs_id = ov_id[0];
+	if (!of_overlay_remove(&ovcs_id)) {
+		unittest(0, "%s was destroyed @\"%s\"\n",
+				overlay_name_from_nr(overlay_nr + 0),
+				unittest_path(unittest_nr,
+					PDEV_OVERLAY));
+		return;
+	}
+
+	/* removing them in order should work */
+	for (i = 1; i >= 0; i--) {
+		ovcs_id = ov_id[i];
+		if (of_overlay_remove(&ovcs_id)) {
+			unittest(0, "%s not destroyed @\"%s\"\n",
+					overlay_name_from_nr(overlay_nr + i),
+					unittest_path(unittest_nr,
+						PDEV_OVERLAY));
+			return;
+		}
+		of_unittest_untrack_overlay(ov_id[i]);
+	}
+
+	unittest(1, "overlay test %d passed\n", 8);
+}
+
+/* test insertion of a bus with parent devices */
+static void __init of_unittest_overlay_10(void)
+{
+	int ret;
+	char *child_path;
+
+	/* device should disable */
+	ret = of_unittest_apply_overlay_check(10, 10, 0, 1, PDEV_OVERLAY);
+	if (unittest(ret == 0,
+			"overlay test %d failed; overlay application\n", 10))
+		return;
+
+	child_path = kasprintf(GFP_KERNEL, "%s/test-unittest101",
+			unittest_path(10, PDEV_OVERLAY));
+	if (unittest(child_path, "overlay test %d failed; kasprintf\n", 10))
+		return;
+
+	ret = of_path_device_type_exists(child_path, PDEV_OVERLAY);
+	kfree(child_path);
+
+	unittest(ret, "overlay test %d failed; no child device\n", 10);
+}
+
+/* test insertion of a bus with parent devices (and revert) */
+static void __init of_unittest_overlay_11(void)
+{
+	int ret;
+
+	/* device should disable */
+	ret = of_unittest_apply_revert_overlay_check(11, 11, 0, 1,
+			PDEV_OVERLAY);
+	unittest(ret == 0, "overlay test %d failed; overlay apply\n", 11);
+}
+
+#if IS_BUILTIN(CONFIG_I2C) && IS_ENABLED(CONFIG_OF_OVERLAY)
+
+struct unittest_i2c_bus_data {
+	struct platform_device	*pdev;
+	struct i2c_adapter	adap;
+};
+
+static int unittest_i2c_master_xfer(struct i2c_adapter *adap,
+		struct i2c_msg *msgs, int num)
+{
+	struct unittest_i2c_bus_data *std = i2c_get_adapdata(adap);
+
+	(void)std;
+
+	return num;
+}
+
+static u32 unittest_i2c_functionality(struct i2c_adapter *adap)
+{
+	return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL;
+}
+
+static const struct i2c_algorithm unittest_i2c_algo = {
+	.master_xfer	= unittest_i2c_master_xfer,
+	.functionality	= unittest_i2c_functionality,
+};
+
+static int unittest_i2c_bus_probe(struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+	struct device_node *np = dev->of_node;
+	struct unittest_i2c_bus_data *std;
+	struct i2c_adapter *adap;
+	int ret;
+
+	if (np == NULL) {
+		dev_err(dev, "No OF data for device\n");
+		return -EINVAL;
+
+	}
+
+	dev_dbg(dev, "%s for node @%pOF\n", __func__, np);
+
+	std = devm_kzalloc(dev, sizeof(*std), GFP_KERNEL);
+	if (!std) {
+		dev_err(dev, "Failed to allocate unittest i2c data\n");
+		return -ENOMEM;
+	}
+
+	/* link them together */
+	std->pdev = pdev;
+	platform_set_drvdata(pdev, std);
+
+	adap = &std->adap;
+	i2c_set_adapdata(adap, std);
+	adap->nr = -1;
+	strlcpy(adap->name, pdev->name, sizeof(adap->name));
+	adap->class = I2C_CLASS_DEPRECATED;
+	adap->algo = &unittest_i2c_algo;
+	adap->dev.parent = dev;
+	adap->dev.of_node = dev->of_node;
+	adap->timeout = 5 * HZ;
+	adap->retries = 3;
+
+	ret = i2c_add_numbered_adapter(adap);
+	if (ret != 0) {
+		dev_err(dev, "Failed to add I2C adapter\n");
+		return ret;
+	}
+
+	return 0;
+}
+
+static int unittest_i2c_bus_remove(struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+	struct device_node *np = dev->of_node;
+	struct unittest_i2c_bus_data *std = platform_get_drvdata(pdev);
+
+	dev_dbg(dev, "%s for node @%pOF\n", __func__, np);
+	i2c_del_adapter(&std->adap);
+
+	return 0;
+}
+
+static const struct of_device_id unittest_i2c_bus_match[] = {
+	{ .compatible = "unittest-i2c-bus", },
+	{},
+};
+
+static struct platform_driver unittest_i2c_bus_driver = {
+	.probe			= unittest_i2c_bus_probe,
+	.remove			= unittest_i2c_bus_remove,
+	.driver = {
+		.name		= "unittest-i2c-bus",
+		.of_match_table	= of_match_ptr(unittest_i2c_bus_match),
+	},
+};
+
+static int unittest_i2c_dev_probe(struct i2c_client *client,
+		const struct i2c_device_id *id)
+{
+	struct device *dev = &client->dev;
+	struct device_node *np = client->dev.of_node;
+
+	if (!np) {
+		dev_err(dev, "No OF node\n");
+		return -EINVAL;
+	}
+
+	dev_dbg(dev, "%s for node @%pOF\n", __func__, np);
+
+	return 0;
+};
+
+static int unittest_i2c_dev_remove(struct i2c_client *client)
+{
+	struct device *dev = &client->dev;
+	struct device_node *np = client->dev.of_node;
+
+	dev_dbg(dev, "%s for node @%pOF\n", __func__, np);
+	return 0;
+}
+
+static const struct i2c_device_id unittest_i2c_dev_id[] = {
+	{ .name = "unittest-i2c-dev" },
+	{ }
+};
+
+static struct i2c_driver unittest_i2c_dev_driver = {
+	.driver = {
+		.name = "unittest-i2c-dev",
+	},
+	.probe = unittest_i2c_dev_probe,
+	.remove = unittest_i2c_dev_remove,
+	.id_table = unittest_i2c_dev_id,
+};
+
+#if IS_BUILTIN(CONFIG_I2C_MUX)
+
+static int unittest_i2c_mux_select_chan(struct i2c_mux_core *muxc, u32 chan)
+{
+	return 0;
+}
+
+static int unittest_i2c_mux_probe(struct i2c_client *client,
+		const struct i2c_device_id *id)
+{
+	int i, nchans;
+	struct device *dev = &client->dev;
+	struct i2c_adapter *adap = to_i2c_adapter(dev->parent);
+	struct device_node *np = client->dev.of_node, *child;
+	struct i2c_mux_core *muxc;
+	u32 reg, max_reg;
+
+	dev_dbg(dev, "%s for node @%pOF\n", __func__, np);
+
+	if (!np) {
+		dev_err(dev, "No OF node\n");
+		return -EINVAL;
+	}
+
+	max_reg = (u32)-1;
+	for_each_child_of_node(np, child) {
+		if (of_property_read_u32(child, "reg", &reg))
+			continue;
+		if (max_reg == (u32)-1 || reg > max_reg)
+			max_reg = reg;
+	}
+	nchans = max_reg == (u32)-1 ? 0 : max_reg + 1;
+	if (nchans == 0) {
+		dev_err(dev, "No channels\n");
+		return -EINVAL;
+	}
+
+	muxc = i2c_mux_alloc(adap, dev, nchans, 0, 0,
+			     unittest_i2c_mux_select_chan, NULL);
+	if (!muxc)
+		return -ENOMEM;
+	for (i = 0; i < nchans; i++) {
+		if (i2c_mux_add_adapter(muxc, 0, i, 0)) {
+			dev_err(dev, "Failed to register mux #%d\n", i);
+			i2c_mux_del_adapters(muxc);
+			return -ENODEV;
+		}
+	}
+
+	i2c_set_clientdata(client, muxc);
+
+	return 0;
+};
+
+static int unittest_i2c_mux_remove(struct i2c_client *client)
+{
+	struct device *dev = &client->dev;
+	struct device_node *np = client->dev.of_node;
+	struct i2c_mux_core *muxc = i2c_get_clientdata(client);
+
+	dev_dbg(dev, "%s for node @%pOF\n", __func__, np);
+	i2c_mux_del_adapters(muxc);
+	return 0;
+}
+
+static const struct i2c_device_id unittest_i2c_mux_id[] = {
+	{ .name = "unittest-i2c-mux" },
+	{ }
+};
+
+static struct i2c_driver unittest_i2c_mux_driver = {
+	.driver = {
+		.name = "unittest-i2c-mux",
+	},
+	.probe = unittest_i2c_mux_probe,
+	.remove = unittest_i2c_mux_remove,
+	.id_table = unittest_i2c_mux_id,
+};
+
+#endif
+
+static int of_unittest_overlay_i2c_init(void)
+{
+	int ret;
+
+	ret = i2c_add_driver(&unittest_i2c_dev_driver);
+	if (unittest(ret == 0,
+			"could not register unittest i2c device driver\n"))
+		return ret;
+
+	ret = platform_driver_register(&unittest_i2c_bus_driver);
+	if (unittest(ret == 0,
+			"could not register unittest i2c bus driver\n"))
+		return ret;
+
+#if IS_BUILTIN(CONFIG_I2C_MUX)
+	ret = i2c_add_driver(&unittest_i2c_mux_driver);
+	if (unittest(ret == 0,
+			"could not register unittest i2c mux driver\n"))
+		return ret;
+#endif
+
+	return 0;
+}
+
+static void of_unittest_overlay_i2c_cleanup(void)
+{
+#if IS_BUILTIN(CONFIG_I2C_MUX)
+	i2c_del_driver(&unittest_i2c_mux_driver);
+#endif
+	platform_driver_unregister(&unittest_i2c_bus_driver);
+	i2c_del_driver(&unittest_i2c_dev_driver);
+}
+
+static void __init of_unittest_overlay_i2c_12(void)
+{
+	/* device should enable */
+	if (of_unittest_apply_overlay_check(12, 12, 0, 1, I2C_OVERLAY))
+		return;
+
+	unittest(1, "overlay test %d passed\n", 12);
+}
+
+/* test deactivation of device */
+static void __init of_unittest_overlay_i2c_13(void)
+{
+	/* device should disable */
+	if (of_unittest_apply_overlay_check(13, 13, 1, 0, I2C_OVERLAY))
+		return;
+
+	unittest(1, "overlay test %d passed\n", 13);
+}
+
+/* just check for i2c mux existence */
+static void of_unittest_overlay_i2c_14(void)
+{
+}
+
+static void __init of_unittest_overlay_i2c_15(void)
+{
+	/* device should enable */
+	if (of_unittest_apply_overlay_check(15, 15, 0, 1, I2C_OVERLAY))
+		return;
+
+	unittest(1, "overlay test %d passed\n", 15);
+}
+
+#else
+
+static inline void of_unittest_overlay_i2c_14(void) { }
+static inline void of_unittest_overlay_i2c_15(void) { }
+
+#endif
+
+static void __init of_unittest_overlay(void)
+{
+	struct device_node *bus_np = NULL;
+
+	if (platform_driver_register(&unittest_driver)) {
+		unittest(0, "could not register unittest driver\n");
+		goto out;
+	}
+
+	bus_np = of_find_node_by_path(bus_path);
+	if (bus_np == NULL) {
+		unittest(0, "could not find bus_path \"%s\"\n", bus_path);
+		goto out;
+	}
+
+	if (of_platform_default_populate(bus_np, NULL, NULL)) {
+		unittest(0, "could not populate bus @ \"%s\"\n", bus_path);
+		goto out;
+	}
+
+	if (!of_unittest_device_exists(100, PDEV_OVERLAY)) {
+		unittest(0, "could not find unittest0 @ \"%s\"\n",
+				unittest_path(100, PDEV_OVERLAY));
+		goto out;
+	}
+
+	if (of_unittest_device_exists(101, PDEV_OVERLAY)) {
+		unittest(0, "unittest1 @ \"%s\" should not exist\n",
+				unittest_path(101, PDEV_OVERLAY));
+		goto out;
+	}
+
+	unittest(1, "basic infrastructure of overlays passed");
+
+	/* tests in sequence */
+	of_unittest_overlay_0();
+	of_unittest_overlay_1();
+	of_unittest_overlay_2();
+	of_unittest_overlay_3();
+	of_unittest_overlay_4();
+	of_unittest_overlay_5();
+	of_unittest_overlay_6();
+	of_unittest_overlay_8();
+
+	of_unittest_overlay_10();
+	of_unittest_overlay_11();
+
+#if IS_BUILTIN(CONFIG_I2C)
+	if (unittest(of_unittest_overlay_i2c_init() == 0, "i2c init failed\n"))
+		goto out;
+
+	of_unittest_overlay_i2c_12();
+	of_unittest_overlay_i2c_13();
+	of_unittest_overlay_i2c_14();
+	of_unittest_overlay_i2c_15();
+
+	of_unittest_overlay_i2c_cleanup();
+#endif
+
+	of_unittest_destroy_tracked_overlays();
+
+out:
+	of_node_put(bus_np);
+}
+
+#else
+static inline void __init of_unittest_overlay(void) { }
+#endif
+
+#ifdef CONFIG_OF_OVERLAY
+
+/*
+ * __dtb_ot_begin[] and __dtb_ot_end[] are created by cmd_dt_S_dtb
+ * in scripts/Makefile.lib
+ */
+
+#define OVERLAY_INFO_EXTERN(name) \
+	extern uint8_t __dtb_##name##_begin[]; \
+	extern uint8_t __dtb_##name##_end[]
+
+#define OVERLAY_INFO(overlay_name, expected)             \
+{	.dtb_begin       = __dtb_##overlay_name##_begin, \
+	.dtb_end         = __dtb_##overlay_name##_end,   \
+	.expected_result = expected,                     \
+	.name            = #overlay_name,                \
+}
+
+struct overlay_info {
+	uint8_t		*dtb_begin;
+	uint8_t		*dtb_end;
+	int		expected_result;
+	int		overlay_id;
+	char		*name;
+};
+
+OVERLAY_INFO_EXTERN(overlay_base);
+OVERLAY_INFO_EXTERN(overlay);
+OVERLAY_INFO_EXTERN(overlay_0);
+OVERLAY_INFO_EXTERN(overlay_1);
+OVERLAY_INFO_EXTERN(overlay_2);
+OVERLAY_INFO_EXTERN(overlay_3);
+OVERLAY_INFO_EXTERN(overlay_4);
+OVERLAY_INFO_EXTERN(overlay_5);
+OVERLAY_INFO_EXTERN(overlay_6);
+OVERLAY_INFO_EXTERN(overlay_7);
+OVERLAY_INFO_EXTERN(overlay_8);
+OVERLAY_INFO_EXTERN(overlay_9);
+OVERLAY_INFO_EXTERN(overlay_10);
+OVERLAY_INFO_EXTERN(overlay_11);
+OVERLAY_INFO_EXTERN(overlay_12);
+OVERLAY_INFO_EXTERN(overlay_13);
+OVERLAY_INFO_EXTERN(overlay_15);
+OVERLAY_INFO_EXTERN(overlay_bad_phandle);
+OVERLAY_INFO_EXTERN(overlay_bad_symbol);
+
+/* order of entries is hard-coded into users of overlays[] */
+static struct overlay_info overlays[] = {
+	OVERLAY_INFO(overlay_base, -9999),
+	OVERLAY_INFO(overlay, 0),
+	OVERLAY_INFO(overlay_0, 0),
+	OVERLAY_INFO(overlay_1, 0),
+	OVERLAY_INFO(overlay_2, 0),
+	OVERLAY_INFO(overlay_3, 0),
+	OVERLAY_INFO(overlay_4, 0),
+	OVERLAY_INFO(overlay_5, 0),
+	OVERLAY_INFO(overlay_6, 0),
+	OVERLAY_INFO(overlay_7, 0),
+	OVERLAY_INFO(overlay_8, 0),
+	OVERLAY_INFO(overlay_9, 0),
+	OVERLAY_INFO(overlay_10, 0),
+	OVERLAY_INFO(overlay_11, 0),
+	OVERLAY_INFO(overlay_12, 0),
+	OVERLAY_INFO(overlay_13, 0),
+	OVERLAY_INFO(overlay_15, 0),
+	OVERLAY_INFO(overlay_bad_phandle, -EINVAL),
+	OVERLAY_INFO(overlay_bad_symbol, -EINVAL),
+	{}
+};
+
+static struct device_node *overlay_base_root;
+
+static void * __init dt_alloc_memory(u64 size, u64 align)
+{
+	return memblock_virt_alloc(size, align);
+}
+
+/*
+ * Create base device tree for the overlay unittest.
+ *
+ * This is called from very early boot code.
+ *
+ * Do as much as possible the same way as done in __unflatten_device_tree
+ * and other early boot steps for the normal FDT so that the overlay base
+ * unflattened tree will have the same characteristics as the real tree
+ * (such as having memory allocated by the early allocator).  The goal
+ * is to test "the real thing" as much as possible, and test "test setup
+ * code" as little as possible.
+ *
+ * Have to stop before resolving phandles, because that uses kmalloc.
+ */
+void __init unittest_unflatten_overlay_base(void)
+{
+	struct overlay_info *info;
+	u32 data_size;
+	void *new_fdt;
+	u32 size;
+
+	info = &overlays[0];
+
+	if (info->expected_result != -9999) {
+		pr_err("No dtb 'overlay_base' to attach\n");
+		return;
+	}
+
+	data_size = info->dtb_end - info->dtb_begin;
+	if (!data_size) {
+		pr_err("No dtb 'overlay_base' to attach\n");
+		return;
+	}
+
+	size = fdt_totalsize(info->dtb_begin);
+	if (size != data_size) {
+		pr_err("dtb 'overlay_base' header totalsize != actual size");
+		return;
+	}
+
+	new_fdt = dt_alloc_memory(size, roundup_pow_of_two(FDT_V17_SIZE));
+	if (!new_fdt) {
+		pr_err("alloc for dtb 'overlay_base' failed");
+		return;
+	}
+
+	memcpy(new_fdt, info->dtb_begin, size);
+
+	__unflatten_device_tree(new_fdt, NULL, &overlay_base_root,
+				dt_alloc_memory, true);
+}
+
+/*
+ * The purpose of of_unittest_overlay_data_add is to add an
+ * overlay in the normal fashion.  This is a test of the whole
+ * picture, instead of testing individual elements.
+ *
+ * A secondary purpose is to be able to verify that the contents of
+ * /proc/device-tree/ contains the updated structure and values from
+ * the overlay.  That must be verified separately in user space.
+ *
+ * Return 0 on unexpected error.
+ */
+static int __init overlay_data_apply(const char *overlay_name, int *overlay_id)
+{
+	struct overlay_info *info;
+	int found = 0;
+	int k;
+	int ret;
+	u32 size;
+
+	for (k = 0, info = overlays; info && info->name; info++, k++) {
+		if (!strcmp(overlay_name, info->name)) {
+			found = 1;
+			break;
+		}
+	}
+	if (!found) {
+		pr_err("no overlay data for %s\n", overlay_name);
+		return 0;
+	}
+
+	size = info->dtb_end - info->dtb_begin;
+	if (!size)
+		pr_err("no overlay data for %s\n", overlay_name);
+
+	ret = of_overlay_fdt_apply(info->dtb_begin, size, &info->overlay_id);
+	if (overlay_id)
+		*overlay_id = info->overlay_id;
+	if (ret < 0)
+		goto out;
+
+	pr_debug("%s applied\n", overlay_name);
+
+out:
+	if (ret != info->expected_result)
+		pr_err("of_overlay_fdt_apply() expected %d, ret=%d, %s\n",
+		       info->expected_result, ret, overlay_name);
+
+	return (ret == info->expected_result);
+}
+
+/*
+ * The purpose of of_unittest_overlay_high_level is to add an overlay
+ * in the normal fashion.  This is a test of the whole picture,
+ * instead of individual elements.
+ *
+ * The first part of the function is _not_ normal overlay usage; it is
+ * finishing splicing the base overlay device tree into the live tree.
+ */
+static __init void of_unittest_overlay_high_level(void)
+{
+	struct device_node *last_sibling;
+	struct device_node *np;
+	struct device_node *of_symbols;
+	struct device_node *overlay_base_symbols;
+	struct device_node **pprev;
+	struct property *prop;
+
+	if (!overlay_base_root) {
+		unittest(0, "overlay_base_root not initialized\n");
+		return;
+	}
+
+	/*
+	 * Could not fixup phandles in unittest_unflatten_overlay_base()
+	 * because kmalloc() was not yet available.
+	 */
+	of_overlay_mutex_lock();
+	of_resolve_phandles(overlay_base_root);
+	of_overlay_mutex_unlock();
+
+
+	/*
+	 * do not allow overlay_base to duplicate any node already in
+	 * tree, this greatly simplifies the code
+	 */
+
+	/*
+	 * remove overlay_base_root node "__local_fixups", after
+	 * being used by of_resolve_phandles()
+	 */
+	pprev = &overlay_base_root->child;
+	for (np = overlay_base_root->child; np; np = np->sibling) {
+		if (!of_node_cmp(np->name, "__local_fixups__")) {
+			*pprev = np->sibling;
+			break;
+		}
+		pprev = &np->sibling;
+	}
+
+	/* remove overlay_base_root node "__symbols__" if in live tree */
+	of_symbols = of_get_child_by_name(of_root, "__symbols__");
+	if (of_symbols) {
+		/* will have to graft properties from node into live tree */
+		pprev = &overlay_base_root->child;
+		for (np = overlay_base_root->child; np; np = np->sibling) {
+			if (!of_node_cmp(np->name, "__symbols__")) {
+				overlay_base_symbols = np;
+				*pprev = np->sibling;
+				break;
+			}
+			pprev = &np->sibling;
+		}
+	}
+
+	for (np = overlay_base_root->child; np; np = np->sibling) {
+		if (of_get_child_by_name(of_root, np->name)) {
+			unittest(0, "illegal node name in overlay_base %s",
+				np->name);
+			return;
+		}
+	}
+
+	/*
+	 * overlay 'overlay_base' is not allowed to have root
+	 * properties, so only need to splice nodes into main device tree.
+	 *
+	 * root node of *overlay_base_root will not be freed, it is lost
+	 * memory.
+	 */
+
+	for (np = overlay_base_root->child; np; np = np->sibling)
+		np->parent = of_root;
+
+	mutex_lock(&of_mutex);
+
+	for (last_sibling = np = of_root->child; np; np = np->sibling)
+		last_sibling = np;
+
+	if (last_sibling)
+		last_sibling->sibling = overlay_base_root->child;
+	else
+		of_root->child = overlay_base_root->child;
+
+	for_each_of_allnodes_from(overlay_base_root, np)
+		__of_attach_node_sysfs(np);
+
+	if (of_symbols) {
+		struct property *new_prop;
+		for_each_property_of_node(overlay_base_symbols, prop) {
+
+			new_prop = __of_prop_dup(prop, GFP_KERNEL);
+			if (!new_prop) {
+				unittest(0, "__of_prop_dup() of '%s' from overlay_base node __symbols__",
+					 prop->name);
+				goto err_unlock;
+			}
+			if (__of_add_property(of_symbols, new_prop)) {
+				/* "name" auto-generated by unflatten */
+				if (!strcmp(new_prop->name, "name"))
+					continue;
+				unittest(0, "duplicate property '%s' in overlay_base node __symbols__",
+					 prop->name);
+				goto err_unlock;
+			}
+			if (__of_add_property_sysfs(of_symbols, new_prop)) {
+				unittest(0, "unable to add property '%s' in overlay_base node __symbols__ to sysfs",
+					 prop->name);
+				goto err_unlock;
+			}
+		}
+	}
+
+	mutex_unlock(&of_mutex);
+
+
+	/* now do the normal overlay usage test */
+
+	unittest(overlay_data_apply("overlay", NULL),
+		 "Adding overlay 'overlay' failed\n");
+
+	unittest(overlay_data_apply("overlay_bad_phandle", NULL),
+		 "Adding overlay 'overlay_bad_phandle' failed\n");
+
+	unittest(overlay_data_apply("overlay_bad_symbol", NULL),
+		 "Adding overlay 'overlay_bad_symbol' failed\n");
+
+	return;
+
+err_unlock:
+	mutex_unlock(&of_mutex);
+}
+
+#else
+
+static inline __init void of_unittest_overlay_high_level(void) {}
+
+#endif
+
+static int __init of_unittest(void)
+{
+	struct device_node *np;
+	int res;
+
+	/* adding data for unittest */
+	res = unittest_data_add();
+	if (res)
+		return res;
+	if (!of_aliases)
+		of_aliases = of_find_node_by_path("/aliases");
+
+	np = of_find_node_by_path("/testcase-data/phandle-tests/consumer-a");
+	if (!np) {
+		pr_info("No testcase data in device tree; not running tests\n");
+		return 0;
+	}
+	of_node_put(np);
+
+	pr_info("start of unittest - you will see error messages\n");
+	of_unittest_check_tree_linkage();
+	of_unittest_check_phandles();
+	of_unittest_find_node_by_name();
+	of_unittest_dynamic();
+	of_unittest_parse_phandle_with_args();
+	of_unittest_parse_phandle_with_args_map();
+	of_unittest_printf();
+	of_unittest_property_string();
+	of_unittest_property_copy();
+	of_unittest_changeset();
+	of_unittest_parse_interrupts();
+	of_unittest_parse_interrupts_extended();
+	of_unittest_match_node();
+	of_unittest_platform_populate();
+	of_unittest_overlay();
+
+	/* Double check linkage after removing testcase data */
+	of_unittest_check_tree_linkage();
+
+	of_unittest_overlay_high_level();
+
+	pr_info("end of unittest - %i passed, %i failed\n",
+		unittest_results.passed, unittest_results.failed);
+
+	return 0;
+}
+late_initcall(of_unittest);