[nrf fromlist] tests: boards: nrf: add rram_throttling test

Verifies that the throttling is working for boards that enable
CONFIG_SOC_FLASH_NRF_THROTTLING

Upstream PR #: 97565

Signed-off-by: Riadh Ghaddab <[email protected]>
(cherry picked from commit c7a030f96113480ca6def26c94bf999a5dcd4800)

Author: rghaddab

tests/boards/nrf/rram_throttling/CMakeLists.txt

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+# Copyright (c) 2025 Nordic Semiconductor ASA
+# SPDX-License-Identifier: Apache-2.0
+
+cmake_minimum_required(VERSION 3.20.0)
+find_package(Zephyr REQUIRED HINTS $ENV{ZEPHYR_BASE})
+project(rram_throttling)
+
+target_sources(app PRIVATE src/main.c)

tests/boards/nrf/rram_throttling/README.rst

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+RRAM Throttling Testing
+#######################
+
+Testing the throttling mechanism and verify that the write delay
+corresponds to the delay defined in CONFIG_NRF_RRAM_THROTTLING_DELAY.

tests/boards/nrf/rram_throttling/prj.conf

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+# Copyright (c) 2025 Nordic Semiconductor ASA
+# SPDX-License-Identifier: Apache-2.0
+
+CONFIG_FLASH=y
+CONFIG_ZTEST=y
+CONFIG_SOC_FLASH_NRF_THROTTLING=y

tests/boards/nrf/rram_throttling/src/main.c

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+/*
+ * Copyright (c) 2025 Nordic Semiconductor ASA
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+#include <zephyr/kernel.h>
+#include <zephyr/ztest.h>
+#include <zephyr/drivers/flash.h>
+#include <zephyr/devicetree.h>
+#include <zephyr/storage/flash_map.h>
+
+#define TEST_AREA storage_partition
+
+/* TEST_AREA is only defined for configurations that rely on
+ * fixed-partition nodes.
+ */
+#if defined(TEST_AREA)
+#define TEST_AREA_OFFSET FIXED_PARTITION_OFFSET(TEST_AREA)
+#define TEST_AREA_SIZE   FIXED_PARTITION_SIZE(TEST_AREA)
+#define TEST_AREA_DEVICE FIXED_PARTITION_DEVICE(TEST_AREA)
+#else
+#error "Unsupported configuraiton"
+#endif
+
+#define BUF_SIZE        512
+#define TEST_ITERATIONS 100
+/* Expected delay in ms: In this expression CONFIG_NRF_RRAM_THROTTLING_DELAY
+ * is expressed in microseconds and CONFIG_NRF_RRAM_THROTTLING_DATA_BLOCK is in
+ * number of write lines of 16 bytes each.
+ */
+#define EXPECTED_DELAY                                                                             \
+	((TEST_ITERATIONS * BUF_SIZE * CONFIG_NRF_RRAM_THROTTLING_DELAY) /                         \
+	 (CONFIG_NRF_RRAM_THROTTLING_DATA_BLOCK * 16 * 1000))
+#if !defined(CONFIG_FLASH_HAS_EXPLICIT_ERASE) && !defined(CONFIG_FLASH_HAS_NO_EXPLICIT_ERASE)
+#error There is no flash device enabled or it is missing Kconfig options
+#endif
+
+static const struct device *const flash_dev = TEST_AREA_DEVICE;
+static uint8_t __aligned(4) buf[BUF_SIZE];
+
+static void *rram_throttling_setup(void)
+{
+	zassert_true(device_is_ready(flash_dev));
+
+	TC_PRINT("Test will run on device %s\n", flash_dev->name);
+	TC_PRINT("TEST_AREA_OFFSET = 0x%lx\n", (unsigned long)TEST_AREA_OFFSET);
+	TC_PRINT("TEST_AREA_SIZE   = 0x%lx\n", (unsigned long)TEST_AREA_SIZE);
+
+	return NULL;
+}
+
+ZTEST(rram_throttling, test_flash_throttling)
+{
+	int rc;
+	uint32_t start = TEST_AREA_OFFSET;
+
+#if !defined(CONFIG_SOC_FLASH_NRF_THROTTLING)
+	ztest_test_skip();
+#endif
+
+	int64_t ts = k_uptime_get();
+
+	for (int i = 0; i < TEST_ITERATIONS; i++) {
+		rc = flash_write(flash_dev, start, buf, BUF_SIZE);
+		zassert_equal(rc, 0, "Cannot write to flash");
+	}
+	/* Delay measured in milliseconds */
+	int64_t delta = k_uptime_delta(&ts);
+
+	zassert_true(delta > EXPECTED_DELAY, "Invalid delay, expected > %d, measured: %lld",
+		     EXPECTED_DELAY, delta);
+}
+
+ZTEST_SUITE(rram_throttling, NULL, rram_throttling_setup, NULL, NULL, NULL);

tests/boards/nrf/rram_throttling/testcase.yaml

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+# Copyright (c) 2025 Nordic Semiconductor ASA
+# SPDX-License-Identifier: Apache-2.0
+
+common:
+  tags:
+    - drivers
+    - flash
+tests:
+  flash.throttling:
+    harness: ztest
+    harness_config:
+      fixture: external_flash
+    platform_allow:
+      - nrf54l15dk/nrf54l15/cpuapp
+      - nrf54l15dk/nrf54l10/cpuapp