diff --git a/drivers/of/unittest-data/Makefile b/drivers/of/unittest-data/Makefile
index 9b6807065827..009f4045c8e4 100644
--- a/drivers/of/unittest-data/Makefile
+++ b/drivers/of/unittest-data/Makefile
@@ -21,7 +21,13 @@ obj-$(CONFIG_OF_OVERLAY) += overlay.dtb.o \
 			    overlay_bad_add_dup_prop.dtb.o \
 			    overlay_bad_phandle.dtb.o \
 			    overlay_bad_symbol.dtb.o \
-			    overlay_base.dtb.o
+			    overlay_base.dtb.o \
+			    overlay_gpio_01.dtb.o \
+			    overlay_gpio_02a.dtb.o \
+			    overlay_gpio_02b.dtb.o \
+			    overlay_gpio_03.dtb.o \
+			    overlay_gpio_04a.dtb.o \
+			    overlay_gpio_04b.dtb.o
 
 # enable creation of __symbols__ node
 DTC_FLAGS_overlay += -@
diff --git a/drivers/of/unittest-data/overlay_gpio_01.dts b/drivers/of/unittest-data/overlay_gpio_01.dts
new file mode 100644
index 000000000000..f039e8bce3b6
--- /dev/null
+++ b/drivers/of/unittest-data/overlay_gpio_01.dts
@@ -0,0 +1,23 @@
+// SPDX-License-Identifier: GPL-2.0
+/dts-v1/;
+/plugin/;
+
+&unittest_test_bus {
+	#address-cells = <1>;
+	#size-cells = <0>;
+	gpio_01 {
+		compatible = "unittest-gpio";
+		reg = <0>;
+		gpio-controller;
+		#gpio-cells = <2>;
+		ngpios = <2>;
+		gpio-line-names = "line-A", "line-B";
+
+		line_b {
+			gpio-hog;
+			gpios = <2 0>;
+			input;
+			line-name = "line-B-input";
+		};
+	};
+};
diff --git a/drivers/of/unittest-data/overlay_gpio_02a.dts b/drivers/of/unittest-data/overlay_gpio_02a.dts
new file mode 100644
index 000000000000..cdafab604793
--- /dev/null
+++ b/drivers/of/unittest-data/overlay_gpio_02a.dts
@@ -0,0 +1,16 @@
+// SPDX-License-Identifier: GPL-2.0
+/dts-v1/;
+/plugin/;
+
+&unittest_test_bus {
+	#address-cells = <1>;
+	#size-cells = <0>;
+	gpio_02 {
+		compatible = "unittest-gpio";
+		reg = <1>;
+		gpio-controller;
+		#gpio-cells = <2>;
+		ngpios = <2>;
+		gpio-line-names = "line-A", "line-B";
+	};
+};
diff --git a/drivers/of/unittest-data/overlay_gpio_02b.dts b/drivers/of/unittest-data/overlay_gpio_02b.dts
new file mode 100644
index 000000000000..0cea0dccafba
--- /dev/null
+++ b/drivers/of/unittest-data/overlay_gpio_02b.dts
@@ -0,0 +1,16 @@
+// SPDX-License-Identifier: GPL-2.0
+/dts-v1/;
+/plugin/;
+
+&unittest_test_bus {
+	#address-cells = <1>;
+	#size-cells = <0>;
+	gpio_02 {
+		line_a {
+			gpio-hog;
+			gpios = <1 0>;
+			input;
+			line-name = "line-A-input";
+		};
+	};
+};
diff --git a/drivers/of/unittest-data/overlay_gpio_03.dts b/drivers/of/unittest-data/overlay_gpio_03.dts
new file mode 100644
index 000000000000..1d5c680fa254
--- /dev/null
+++ b/drivers/of/unittest-data/overlay_gpio_03.dts
@@ -0,0 +1,23 @@
+// SPDX-License-Identifier: GPL-2.0
+/dts-v1/;
+/plugin/;
+
+&unittest_test_bus {
+	#address-cells = <1>;
+	#size-cells = <0>;
+	gpio_03 {
+		compatible = "unittest-gpio";
+		reg = <0>;
+		gpio-controller;
+		#gpio-cells = <2>;
+		ngpios = <2>;
+		gpio-line-names = "line-A", "line-B", "line-C", "line-D";
+
+		line_d {
+			gpio-hog;
+			gpios = <4 0>;
+			input;
+			line-name = "line-D-input";
+		};
+	};
+};
diff --git a/drivers/of/unittest-data/overlay_gpio_04a.dts b/drivers/of/unittest-data/overlay_gpio_04a.dts
new file mode 100644
index 000000000000..d2482cde310e
--- /dev/null
+++ b/drivers/of/unittest-data/overlay_gpio_04a.dts
@@ -0,0 +1,16 @@
+// SPDX-License-Identifier: GPL-2.0
+/dts-v1/;
+/plugin/;
+
+&unittest_test_bus {
+	#address-cells = <1>;
+	#size-cells = <0>;
+	gpio_04 {
+		compatible = "unittest-gpio";
+		reg = <1>;
+		gpio-controller;
+		#gpio-cells = <2>;
+		ngpios = <2>;
+		gpio-line-names = "line-A", "line-B", "line-C", "line-D";
+	};
+};
diff --git a/drivers/of/unittest-data/overlay_gpio_04b.dts b/drivers/of/unittest-data/overlay_gpio_04b.dts
new file mode 100644
index 000000000000..70ad05d759f9
--- /dev/null
+++ b/drivers/of/unittest-data/overlay_gpio_04b.dts
@@ -0,0 +1,16 @@
+// SPDX-License-Identifier: GPL-2.0
+/dts-v1/;
+/plugin/;
+
+&unittest_test_bus {
+	#address-cells = <1>;
+	#size-cells = <0>;
+	gpio_04 {
+		line_c {
+			gpio-hog;
+			gpios = <3 0>;
+			input;
+			line-name = "line-C-input";
+		};
+	};
+};
diff --git a/drivers/of/unittest.c b/drivers/of/unittest.c
index 68b87587b2ef..b1cf9972d866 100644
--- a/drivers/of/unittest.c
+++ b/drivers/of/unittest.c
@@ -24,6 +24,7 @@
 
 #include <linux/i2c.h>
 #include <linux/i2c-mux.h>
+#include <linux/gpio/driver.h>
 
 #include <linux/bitops.h>
 
@@ -46,6 +47,101 @@
 	failed; \
 })
 
+/*
+ * Expected message may have a message level other than KERN_INFO.
+ * Print the expected message only if the current loglevel will allow
+ * the actual message to print.
+ */
+#define EXPECT_BEGIN(level, fmt, ...) \
+	printk(level pr_fmt("EXPECT \\ : ") fmt, ##__VA_ARGS__)
+
+#define EXPECT_END(level, fmt, ...) \
+	printk(level pr_fmt("EXPECT / : ") fmt, ##__VA_ARGS__)
+
+struct unittest_gpio_dev {
+	void __iomem *base;
+	struct gpio_chip chip;
+	spinlock_t gpio_lock;
+};
+
+static int unittest_gpio_chip_request_count;
+static int unittest_gpio_probe_count;
+static int unittest_gpio_probe_pass_count;
+
+static int unittest_gpio_chip_request(struct gpio_chip *chip, unsigned int offset)
+{
+	unittest_gpio_chip_request_count++;
+
+	pr_debug("%s(): %s %d %d\n", __func__, chip->label, offset,
+		 unittest_gpio_chip_request_count);
+	return 0;
+}
+
+static int unittest_gpio_probe(struct platform_device *pdev)
+{
+	struct unittest_gpio_dev *devptr;
+	int ret;
+
+	unittest_gpio_probe_count++;
+
+	devptr = kzalloc(sizeof(*devptr), GFP_KERNEL);
+	if (!devptr)
+		return -ENOMEM;
+
+	spin_lock_init(&devptr->gpio_lock);
+
+	platform_set_drvdata(pdev, devptr);
+
+	devptr->chip.of_node = pdev->dev.of_node;
+	devptr->chip.label = "of-unittest-gpio";
+	devptr->chip.base = -1; /* dynamic allocation */
+	devptr->chip.ngpio = 5;
+	devptr->chip.request = unittest_gpio_chip_request;
+
+	ret = gpiochip_add_data(&devptr->chip, NULL);
+
+	unittest(!ret,
+		 "gpiochip_add_data() for node @%pOF failed, ret = %d\n", devptr->chip.of_node, ret);
+
+	if (!ret)
+		unittest_gpio_probe_pass_count++;
+	return ret;
+}
+
+static int unittest_gpio_remove(struct platform_device *pdev)
+{
+	struct unittest_gpio_dev *gdev = platform_get_drvdata(pdev);
+	struct device *dev = &pdev->dev;
+	struct device_node *np = pdev->dev.of_node;
+
+	dev_dbg(dev, "%s for node @%pOF\n", __func__, np);
+
+	if (!gdev)
+		return -EINVAL;
+
+	if (gdev->chip.base != -1)
+		gpiochip_remove(&gdev->chip);
+
+	platform_set_drvdata(pdev, NULL);
+	kfree(pdev);
+
+	return 0;
+}
+
+static const struct of_device_id unittest_gpio_id[] = {
+	{ .compatible = "unittest-gpio", },
+	{}
+};
+
+static struct platform_driver unittest_gpio_driver = {
+	.probe	= unittest_gpio_probe,
+	.remove	= unittest_gpio_remove,
+	.driver	= {
+		.name		= "unittest-gpio",
+		.of_match_table	= of_match_ptr(unittest_gpio_id),
+	},
+};
+
 static void __init of_unittest_find_node_by_name(void)
 {
 	struct device_node *np;
@@ -2183,6 +2279,151 @@ static inline void of_unittest_overlay_i2c_15(void) { }
 
 #endif
 
+static void __init of_unittest_overlay_gpio(void)
+{
+	int chip_request_count;
+	int probe_pass_count;
+	int ret;
+
+	/*
+	 * tests: apply overlays before registering driver
+	 * Similar to installing a driver as a module, the
+	 * driver is registered after applying the overlays.
+	 *
+	 * - apply overlay_gpio_01
+	 * - apply overlay_gpio_02a
+	 * - apply overlay_gpio_02b
+	 * - register driver
+	 *
+	 * register driver will result in
+	 *   - probe and processing gpio hog for overlay_gpio_01
+	 *   - probe for overlay_gpio_02a
+	 *   - processing gpio for overlay_gpio_02b
+	 *
+	 * overlay_gpio_01 contains gpio node and child gpio hog node
+	 * overlay_gpio_02a contains gpio node
+	 * overlay_gpio_02b contains child gpio hog node
+	 *
+	 * "GPIO line <<int>> (line-*-input) hogged as input"
+	 * messages are the result of the gpio driver probe
+	 * finding the gpio hog node.
+	 */
+
+	unittest(overlay_data_apply("overlay_gpio_01", NULL),
+		 "Adding overlay 'overlay_gpio_01' failed\n");
+
+	unittest(overlay_data_apply("overlay_gpio_02a", NULL),
+		 "Adding overlay 'overlay_gpio_02a' failed\n");
+
+	unittest(overlay_data_apply("overlay_gpio_02b", NULL),
+		 "Adding overlay 'overlay_gpio_02b' failed\n");
+
+	EXPECT_BEGIN(KERN_INFO,
+		     "GPIO line <<int>> (line-B-input) hogged as input\n");
+
+	EXPECT_BEGIN(KERN_INFO,
+		     "GPIO line <<int>> (line-A-input) hogged as input\n");
+
+	probe_pass_count = unittest_gpio_probe_pass_count;
+	chip_request_count = unittest_gpio_chip_request_count;
+
+	ret = platform_driver_register(&unittest_gpio_driver);
+	if (unittest(ret == 0, "could not register unittest gpio driver\n"))
+		return;
+
+	EXPECT_END(KERN_INFO,
+		   "GPIO line <<int>> (line-A-input) hogged as input\n");
+	EXPECT_END(KERN_INFO,
+		   "GPIO line <<int>> (line-B-input) hogged as input\n");
+
+	unittest(probe_pass_count + 2 == unittest_gpio_probe_pass_count,
+		 "unittest_gpio_probe() failed or not called\n");
+
+	unittest(chip_request_count + 2 == unittest_gpio_chip_request_count,
+		 "unittest_gpio_chip_request() called %d times (expected 1 time)\n",
+		 unittest_gpio_chip_request_count - chip_request_count);
+
+	/*
+	 * tests: apply overlays after registering driver
+	 *
+	 * Similar to a driver built-in to the kernel, the
+	 * driver is registered before applying the overlays.
+	 *
+	 * - apply overlay_gpio_03
+	 *
+	 * apply overlay will result in
+	 *   - probe and processing gpio hog.
+	 *
+	 * overlay_gpio_03 contains gpio node and child gpio hog node
+	 */
+
+	EXPECT_BEGIN(KERN_INFO,
+		     "GPIO line <<int>> (line-D-input) hogged as input\n");
+
+	probe_pass_count = unittest_gpio_probe_pass_count;
+	chip_request_count = unittest_gpio_chip_request_count;
+
+	unittest(overlay_data_apply("overlay_gpio_03", NULL),
+		 "Adding overlay 'overlay_gpio_03' failed\n");
+
+	EXPECT_END(KERN_INFO,
+		   "GPIO line <<int>> (line-D-input) hogged as input\n");
+
+	unittest(probe_pass_count + 1 == unittest_gpio_probe_pass_count,
+		 "unittest_gpio_probe() failed or not called\n");
+
+	unittest(chip_request_count + 1 == unittest_gpio_chip_request_count,
+		 "unittest_gpio_chip_request() called %d times (expected 1 time)\n",
+		 unittest_gpio_chip_request_count - chip_request_count);
+
+	/*
+	 * tests: apply overlay containing gpio node but no gpio hog node
+	 *
+	 * - apply overlay_gpio_04a
+	 *
+	 * apply the overlay will result in
+	 *   - probe for overlay_gpio_04a
+	 *
+	 * overlay_gpio_04a contains gpio node
+	 */
+
+	probe_pass_count = unittest_gpio_probe_pass_count;
+
+	/* overlay_gpio_04a contains gpio node */
+
+	unittest(overlay_data_apply("overlay_gpio_04a", NULL),
+		 "Adding overlay 'overlay_gpio_04a' failed\n");
+
+	unittest(probe_pass_count + 1 == unittest_gpio_probe_pass_count,
+		 "unittest_gpio_probe() failed or not called\n");
+
+	/*
+	 * tests: apply overlay containing the gpio hog node
+	 *
+	 * - apply overlay_gpio_04b
+	 *
+	 * apply the overlay will result in
+	 *   - processing gpio for overlay_gpio_04b
+	 *
+	 * overlay_gpio_04b contains child gpio hog node
+	 */
+
+	EXPECT_BEGIN(KERN_INFO,
+		     "GPIO line <<int>> (line-C-input) hogged as input\n");
+
+	chip_request_count = unittest_gpio_chip_request_count;
+
+	unittest(overlay_data_apply("overlay_gpio_04b", NULL),
+		 "Adding overlay 'overlay_gpio_04b' failed\n");
+
+	EXPECT_END(KERN_INFO,
+		   "GPIO line <<int>> (line-C-input) hogged as input\n");
+
+	unittest(chip_request_count + 1 == unittest_gpio_chip_request_count,
+		 "unittest_gpio_chip_request() called %d times (expected 1 time)\n",
+		 unittest_gpio_chip_request_count - chip_request_count);
+}
+
 static void __init of_unittest_overlay(void)
 {
 	struct device_node *bus_np = NULL;
@@ -2242,6 +2483,8 @@ static void __init of_unittest_overlay(void)
 	of_unittest_overlay_i2c_cleanup();
 #endif
 
+	of_unittest_overlay_gpio();
+
 	of_unittest_destroy_tracked_overlays();
 
 out:
@@ -2295,6 +2538,12 @@ struct overlay_info {
 OVERLAY_INFO_EXTERN(overlay_12);
 OVERLAY_INFO_EXTERN(overlay_13);
 OVERLAY_INFO_EXTERN(overlay_15);
+OVERLAY_INFO_EXTERN(overlay_gpio_01);
+OVERLAY_INFO_EXTERN(overlay_gpio_02a);
+OVERLAY_INFO_EXTERN(overlay_gpio_02b);
+OVERLAY_INFO_EXTERN(overlay_gpio_03);
+OVERLAY_INFO_EXTERN(overlay_gpio_04a);
+OVERLAY_INFO_EXTERN(overlay_gpio_04b);
 OVERLAY_INFO_EXTERN(overlay_bad_add_dup_node);
 OVERLAY_INFO_EXTERN(overlay_bad_add_dup_prop);
 OVERLAY_INFO_EXTERN(overlay_bad_phandle);
@@ -2319,6 +2568,12 @@ struct overlay_info {
 	OVERLAY_INFO(overlay_12, 0),
 	OVERLAY_INFO(overlay_13, 0),
 	OVERLAY_INFO(overlay_15, 0),
+	OVERLAY_INFO(overlay_gpio_01, 0),
+	OVERLAY_INFO(overlay_gpio_02a, 0),
+	OVERLAY_INFO(overlay_gpio_02b, 0),
+	OVERLAY_INFO(overlay_gpio_03, 0),
+	OVERLAY_INFO(overlay_gpio_04a, 0),
+	OVERLAY_INFO(overlay_gpio_04b, 0),
 	OVERLAY_INFO(overlay_bad_add_dup_node, -EINVAL),
 	OVERLAY_INFO(overlay_bad_add_dup_prop, -EINVAL),
 	OVERLAY_INFO(overlay_bad_phandle, -EINVAL),
