wifi: iwlwifi: move dBm averaging function into utils

The function really is just a simple math helper. Move it into
iwl-utils.c so that it can also be used by iwlmld.

Signed-off-by: Benjamin Berg <benjamin.berg@intel.com>
Signed-off-by: Miri Korenblit <miriam.rachel.korenblit@intel.com>
Link: https://patch.msgid.link/20250609211928.8cc965af6990.I09bb2137863e888efe756c92d8eb0271ec95456c@changeid

1 files changed, 109 insertions, 0 deletions

diff --git a/drivers/net/wireless/intel/iwlwifi/tests/utils.c b/drivers/net/wireless/intel/iwlwifi/tests/utils.c
new file mode 100644
index 000000000000..df2c3a891e7e
--- /dev/null
+++ b/drivers/net/wireless/intel/iwlwifi/tests/utils.c
@@ -0,0 +1,109 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * KUnit tests for utilities
+ *
+ * Copyright (C) 2024-2025 Intel Corporation
+ */
+#include "../iwl-utils.h"
+#include <kunit/test.h>
+
+MODULE_IMPORT_NS("IWLWIFI");
+
+static const struct average_neg_db_case {
+	const char *desc;
+	u8 neg_dbm[22];
+	s8 result;
+} average_neg_db_cases[] = {
+	{
+		.desc = "Smallest possible value, all filled",
+		.neg_dbm = {
+			128, 128, 128, 128, 128, 128, 128, 128, 128, 128,
+			128, 128, 128, 128, 128, 128, 128, 128, 128, 128,
+			128, 128
+		},
+		.result = -128,
+	},
+	{
+		.desc = "Biggest possible value, all filled",
+		.neg_dbm = {
+			0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+			0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+			0, 0,
+		},
+		.result = 0,
+	},
+	{
+		.desc = "Smallest possible value, partial filled",
+		.neg_dbm = {
+			128, 128, 128, 128, 128, 128, 128, 128, 128, 128,
+			0xff, 0xff, 0xff, 0xff, 0xff,
+			0xff, 0xff, 0xff, 0xff, 0xff,
+			0xff, 0xff,
+		},
+		.result = -128,
+	},
+	{
+		.desc = "Biggest possible value, partial filled",
+		.neg_dbm = {
+			0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+			0xff, 0xff, 0xff, 0xff, 0xff,
+			0xff, 0xff, 0xff, 0xff, 0xff,
+			0xff, 0xff,
+		},
+		.result = 0,
+	},
+	{
+		.desc = "Adding -80dBm to -75dBm until it is still rounded to -79dBm",
+		.neg_dbm = {
+			75, 80, 80, 80, 80, 80, 80, 80, 80, 80,
+			80, 80, 80, 80, 80, 80, 80, 0xff, 0xff, 0xff,
+			0xff, 0xff,
+		},
+		.result = -79,
+	},
+	{
+		.desc = "Adding -80dBm to -75dBm until it is just rounded to -80dBm",
+		.neg_dbm = {
+			75, 80, 80, 80, 80, 80, 80, 80, 80, 80,
+			80, 80, 80, 80, 80, 80, 80, 80, 0xff, 0xff,
+			0xff, 0xff,
+		},
+		.result = -80,
+	},
+};
+
+KUNIT_ARRAY_PARAM_DESC(average_neg_db, average_neg_db_cases, desc)
+
+static void test_average_neg_db(struct kunit *test)
+{
+	const struct average_neg_db_case *params = test->param_value;
+	u8 reversed[ARRAY_SIZE(params->neg_dbm)];
+	int i;
+
+	/* Test the values in the given order */
+	KUNIT_ASSERT_EQ(test,
+			iwl_average_neg_dbm(params->neg_dbm,
+					    ARRAY_SIZE(params->neg_dbm)),
+			params->result);
+
+	/* Test in reverse order */
+	for (i = 0; i < ARRAY_SIZE(params->neg_dbm); i++)
+		reversed[ARRAY_SIZE(params->neg_dbm) - i - 1] =
+			params->neg_dbm[i];
+	KUNIT_ASSERT_EQ(test,
+			iwl_average_neg_dbm(reversed,
+					    ARRAY_SIZE(params->neg_dbm)),
+			params->result);
+}
+
+static struct kunit_case average_db_case[] = {
+	KUNIT_CASE_PARAM(test_average_neg_db, average_neg_db_gen_params),
+	{}
+};
+
+static struct kunit_suite average_db = {
+	.name = "iwl-average-db",
+	.test_cases = average_db_case,
+};
+
+kunit_test_suite(average_db);