wifi: iwlwifi: mvm: implement link grading

For selecting what link(s) out of the usable ones
to activate, calculate a grade for a given link.

Calculation of a link grade is done as follows:
1. get the estimated throughput according to the RSSI of the link, this
   will be the base grade
2. get the channel load from the BSS Load Element, subtracting the load
   caused by us. Apply the factor on the grade.
3. puncturing factor: calculate the percentage of the punctured
   subchannels (out of the total subchannels). Apply this on the grade.

The link grading will be used by the link selection mechanism in a later
patch.

Also add KUnit tests for it.

Signed-off-by: Miri Korenblit <miriam.rachel.korenblit@intel.com>
Reviewed-by: Johannes Berg <johannes.berg@intel.com>
Link: https://msgid.link/20240416134215.a6799dbd5643.If137ca6dc443606c7d8c99ec1fc38b325003a7c1@changeid
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

3 files changed, 223 insertions, 0 deletions

diff --git a/drivers/net/wireless/intel/iwlwifi/mvm/tests/Makefile b/drivers/net/wireless/intel/iwlwifi/mvm/tests/Makefile
new file mode 100644
index 000000000000..b13aebbf7d5e
--- /dev/null
+++ b/drivers/net/wireless/intel/iwlwifi/mvm/tests/Makefile
@@ -0,0 +1,3 @@
+iwlmvm-tests-y += module.o links.o
+
+obj-$(CONFIG_IWLWIFI_KUNIT_TESTS) += iwlmvm-tests.o
diff --git a/drivers/net/wireless/intel/iwlwifi/mvm/tests/links.c b/drivers/net/wireless/intel/iwlwifi/mvm/tests/links.c
new file mode 100644
index 000000000000..321d18de1ca3
--- /dev/null
+++ b/drivers/net/wireless/intel/iwlwifi/mvm/tests/links.c
@@ -0,0 +1,210 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * KUnit tests for channel helper functions
+ *
+ * Copyright (C) 2024 Intel Corporation
+ */
+#include <net/mac80211.h>
+#include "../mvm.h"
+#include <kunit/test.h>
+
+MODULE_IMPORT_NS(EXPORTED_FOR_KUNIT_TESTING);
+
+static struct ieee80211_channel chan_5ghz = {
+	.band = NL80211_BAND_5GHZ,
+};
+
+static struct ieee80211_channel chan_6ghz = {
+	.band = NL80211_BAND_6GHZ,
+};
+
+static struct ieee80211_channel chan_2ghz = {
+	.band = NL80211_BAND_2GHZ,
+};
+
+static struct iwl_mvm_phy_ctxt ctx = {};
+
+static struct iwl_mvm_vif_link_info mvm_link = {
+	.phy_ctxt = &ctx,
+	.active = true
+};
+
+static struct cfg80211_bss bss = {};
+
+static struct ieee80211_bss_conf link_conf = {.bss = &bss};
+
+static const struct link_grading_case {
+	const char *desc;
+	const struct cfg80211_chan_def chandef;
+	s32 signal;
+	s16 channel_util;
+	int chan_load_by_us;
+	unsigned int grade;
+} link_grading_cases[] = {
+	{
+		.desc = "UHB, RSSI below range, no factors",
+		.chandef = {
+			.chan = &chan_6ghz,
+			.width = NL80211_CHAN_WIDTH_20,
+		},
+		.signal = -100,
+		.grade = 177,
+	},
+	{
+		.desc = "LB, RSSI in range, no factors",
+		.chandef = {
+			.chan = &chan_2ghz,
+			.width = NL80211_CHAN_WIDTH_20,
+		},
+		.signal = -84,
+		.grade = 344,
+	},
+	{
+		.desc = "HB, RSSI above range, no factors",
+		.chandef = {
+			.chan = &chan_5ghz,
+			.width = NL80211_CHAN_WIDTH_20,
+		},
+		.signal = -50,
+		.grade = 3442,
+	},
+	{
+		.desc = "HB, BSS Load IE (20 percent), inactive link, no puncturing factor",
+		.chandef = {
+			.chan = &chan_5ghz,
+			.width = NL80211_CHAN_WIDTH_20,
+		},
+		.signal = -66,
+		.channel_util = 51,
+		.grade = 1836,
+	},
+	{
+		.desc = "LB, BSS Load IE (20 percent), active link, chan_load_by_us=10 percent. No puncturing factor",
+		.chandef = {
+			.chan = &chan_2ghz,
+			.width = NL80211_CHAN_WIDTH_20,
+		},
+		.signal = -61,
+		.channel_util = 51,
+		.chan_load_by_us = 10,
+		.grade = 2061,
+	},
+	{
+		.desc = "UHB, BSS Load IE (40 percent), active link, chan_load_by_us=50 (invalid) percent. No puncturing factor",
+		.chandef = {
+			.chan = &chan_6ghz,
+			.width = NL80211_CHAN_WIDTH_20,
+		},
+		.signal = -66,
+		.channel_util = 102,
+		.chan_load_by_us = 50,
+		.grade = 1552,
+	},
+	{	.desc = "HB, 80 MHz, no channel load factor, punctured percentage 0",
+		.chandef = {
+			.chan = &chan_5ghz,
+			.width = NL80211_CHAN_WIDTH_80,
+			.punctured = 0x0000
+		},
+		.signal = -72,
+		.grade = 1750,
+	},
+	{	.desc = "HB, 160 MHz, no channel load factor, punctured percentage 25",
+		.chandef = {
+			.chan = &chan_5ghz,
+			.width = NL80211_CHAN_WIDTH_160,
+			.punctured = 0x3
+		},
+		.signal = -72,
+		.grade = 1312,
+	},
+	{	.desc = "UHB, 320 MHz, no channel load factor, punctured percentage 12.5 (2/16)",
+		.chandef = {
+			.chan = &chan_6ghz,
+			.width = NL80211_CHAN_WIDTH_320,
+			.punctured = 0x3
+		},
+		.signal = -72,
+		.grade = 1806,
+	},
+	{	.desc = "HB, 160 MHz, channel load 20, channel load by us 10, punctured percentage 25",
+		.chandef = {
+			.chan = &chan_5ghz,
+			.width = NL80211_CHAN_WIDTH_160,
+			.punctured = 0x3
+		},
+		.channel_util = 51,
+		.chan_load_by_us = 10,
+		.signal = -72,
+		.grade = 1179,
+	},
+};
+
+KUNIT_ARRAY_PARAM_DESC(link_grading, link_grading_cases, desc)
+
+static void setup_link_conf(struct kunit *test)
+{
+	const struct link_grading_case *params = test->param_value;
+	size_t vif_size = sizeof(struct ieee80211_vif) +
+		sizeof(struct iwl_mvm_vif);
+	struct ieee80211_vif *vif = kunit_kzalloc(test, vif_size, GFP_KERNEL);
+	struct ieee80211_bss_load_elem *bss_load;
+	struct element *element;
+	size_t ies_size = sizeof(struct cfg80211_bss_ies) + sizeof(*bss_load) + sizeof(element);
+	struct cfg80211_bss_ies *ies;
+	struct iwl_mvm_vif *mvmvif;
+
+	KUNIT_ASSERT_NOT_NULL(test, vif);
+
+	mvmvif = iwl_mvm_vif_from_mac80211(vif);
+	if (params->chan_load_by_us > 0) {
+		ctx.channel_load_by_us = params->chan_load_by_us;
+		mvmvif->link[0] = &mvm_link;
+	}
+
+	link_conf.vif = vif;
+	link_conf.chanreq.oper = params->chandef;
+	bss.signal = DBM_TO_MBM(params->signal);
+
+	ies = kunit_kzalloc(test, ies_size, GFP_KERNEL);
+	KUNIT_ASSERT_NOT_NULL(test, ies);
+	ies->len = sizeof(*bss_load) + sizeof(struct element);
+
+	element = (void *)ies->data;
+	element->datalen = sizeof(*bss_load);
+	element->id = 11;
+
+	bss_load = (void *)element->data;
+	bss_load->channel_util = params->channel_util;
+
+	rcu_assign_pointer(bss.ies, ies);
+}
+
+static void test_link_grading(struct kunit *test)
+{
+	const struct link_grading_case *params = test->param_value;
+	unsigned int ret;
+
+	setup_link_conf(test);
+
+	rcu_read_lock();
+	ret = iwl_mvm_get_link_grade(&link_conf);
+	rcu_read_unlock();
+
+	KUNIT_EXPECT_EQ(test, ret, params->grade);
+
+	kunit_kfree(test, link_conf.vif);
+	RCU_INIT_POINTER(bss.ies, NULL);
+}
+
+static struct kunit_case link_grading_test_cases[] = {
+	KUNIT_CASE_PARAM(test_link_grading, link_grading_gen_params),
+	{}
+};
+
+static struct kunit_suite link_grading = {
+	.name = "iwlmvm-link-grading",
+	.test_cases = link_grading_test_cases,
+};
+
+kunit_test_suite(link_grading);
diff --git a/drivers/net/wireless/intel/iwlwifi/mvm/tests/module.c b/drivers/net/wireless/intel/iwlwifi/mvm/tests/module.c
new file mode 100644
index 000000000000..f556acbac77f
--- /dev/null
+++ b/drivers/net/wireless/intel/iwlwifi/mvm/tests/module.c
@@ -0,0 +1,10 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * This is just module boilerplate for the iwlmvm kunit module.
+ *
+ * Copyright (C) 2024 Intel Corporation
+ */
+#include <linux/module.h>
+
+MODULE_LICENSE("GPL");
+MODULE_DESCRIPTION("kunit tests for iwlmvm");