tests: drivers: gpio: Add loopback test for eGPIO SDP

Added a loopback test for the software-defined eGPIO peripheral.
The test verifies proper operation of the eGPIO output by using
a different processor hardware GPIO input pin.

Signed-off-by: Jakub Zymelka <jakub.zymelka@nordicsemi.no>

tests/drivers/gpio/egpio_basic_api/CMakeLists.txt

@@ -0,0 +1,12 @@
+#
+# Copyright (c) 2024 Nordic Semiconductor ASA
+#
+# SPDX-License-Identifier: LicenseRef-Nordic-5-Clause
+#
+
+cmake_minimum_required(VERSION 3.20.0)
+find_package(Zephyr REQUIRED HINTS $ENV{ZEPHYR_BASE})
+project(egpio_basic_api)
+
+FILE(GLOB app_sources src/test*.c)
+target_sources(app PRIVATE ${app_sources})

tests/drivers/gpio/egpio_basic_api/README.txt

@@ -0,0 +1,18 @@
+eGPIO 2-Pin Test
+###############
+
+This application tests the eGPIO subsystem using a hardware configuration
+where two GPIOs are directly wired together. The test pins are
+identified through a test-specific devicetree binding in the `dts/`
+subdirectory, implemented for specific boards by overlay files in the
+`boards/` directory.
+
+Only boards for which an overlay is present can pass this test.  Boards
+without an overlay, or for which the required wiring is not provided,
+will fail with an error like this:
+
+    Validate device GPIO_0
+    Check GPIO_1 output 7 connected to GPIO_2 input 3
+    FATAL output pin not wired to input pin? (out high => in low)
+
+No special build options are required to make use of the overlay.

tests/drivers/gpio/egpio_basic_api/boards/nrf54l15dk_nrf54l15_cpuapp.overlay

@@ -0,0 +1,21 @@
+/*
+ * Copyright (c) 2024 Nordic Semiconductor ASA
+ *
+ * SPDX-License-Identifier: LicenseRef-Nordic-5-Clause
+ */
+
+/ {
+	resources {
+		compatible = "test-egpio";
+		out-gpios = <&egpio 10 0>;
+		in-gpios = <&gpio1 14 0>;
+	};
+};
+
+&gpiote20 {
+    status = "okay";
+};
+
+&gpio1 {
+    status = "okay";
+};

tests/drivers/gpio/egpio_basic_api/dts/bindings/test-egpio.yaml

@@ -0,0 +1,28 @@
+#
+# Copyright (c) 2024 Nordic Semiconductor ASA
+#
+# SPDX-License-Identifier: LicenseRef-Nordic-5-Clause
+#
+
+description: |
+    This binding provides resources required to build and run the
+    tests/drivers/gpio/egpio_basic_api test in Zephyr.
+
+compatible: "test-egpio"
+
+properties:
+  out-gpios:
+    type: phandle-array
+    required: true
+    description: |
+      Identity of a eGPIO that will be configured as an output.
+      This must be on the instance to which FLPR has access, and physically
+      connected to in-gpios.
+
+  in-gpios:
+    type: phandle-array
+    required: true
+    description: |
+      Identity of a hardware GPIO that will be configured as an input.
+      This must be on the same instance as out-gpios, and physically
+      connected to out-gpios.

tests/drivers/gpio/egpio_basic_api/prj.conf

@@ -0,0 +1,4 @@
+CONFIG_GPIO=y
+CONFIG_ZTEST=y
+CONFIG_ENTROPY_GENERATOR=y
+CONFIG_TEST_RANDOM_GENERATOR=y

tests/drivers/gpio/egpio_basic_api/src/test_egpio.h

@@ -0,0 +1,56 @@
+/*
+ * Copyright (c) 2024 Nordic Semiconductor ASA
+ *
+ * SPDX-License-Identifier: LicenseRef-Nordic-5-Clause
+ */
+
+#ifndef __TEST_EGPIO_H__
+#define __TEST_EGPIO_H__
+
+#include <zephyr/kernel.h>
+#include <zephyr/drivers/gpio.h>
+#include <zephyr/sys/util.h>
+#include <zephyr/ztest.h>
+
+#if DT_NODE_HAS_STATUS(DT_INST(0, test_egpio), okay)
+
+/* Execution of the test requires hardware configuration described in
+ * devicetree. See the test, egpio_basic_api binding local to this test
+ * for details.
+ */
+#define DEV_OUT DT_GPIO_CTLR(DT_INST(0, test_egpio), out_gpios)
+#define DEV_IN DT_GPIO_CTLR(DT_INST(0, test_egpio), in_gpios)
+#define DEV DEV_OUT
+#define PIN_OUT DT_GPIO_PIN(DT_INST(0, test_egpio), out_gpios)
+#define PIN_OUT_FLAGS DT_GPIO_FLAGS(DT_INST(0, test_egpio), out_gpios)
+#define PIN_IN DT_GPIO_PIN(DT_INST(0, test_egpio), in_gpios)
+#define PIN_IN_FLAGS DT_GPIO_FLAGS(DT_INST(0, test_egpio), in_gpios)
+#else
+#error Unsupported board
+#endif
+
+#ifndef PIN_OUT
+/* For build-only testing use fixed pins. */
+#define PIN_OUT 10
+#define PIN_IN 14
+#endif
+
+#define MAX_INT_CNT 3
+struct drv_data {
+	struct gpio_callback gpio_cb;
+	gpio_flags_t mode;
+	int index;
+	int aux;
+};
+
+void test_egpio_pin_read_write(void);
+void test_egpio_callback_add_remove(void);
+void test_egpio_callback_self_remove(void);
+void test_egpio_callback_enable_disable(void);
+void test_egpio_callback_variants(void);
+
+void test_egpio_port(void);
+
+void test_egpio_deprecated(void);
+
+#endif /* __TEST_EGPIO_H__ */