wifi: iwlwifi: mvm: record and return channel survey information

While doing a passive scan, the firmware will report per-channel survey
information. This information is primarily useful for hostapd when doing
an ACS (Automatic Channel Selection). Collect this information and add
it to the result set when getting the survey information.

Signed-off-by: Benjamin Berg <benjamin.berg@intel.com>
Signed-off-by: Miri Korenblit <miriam.rachel.korenblit@intel.com>
Link: https://msgid.link/20240506095953.9287591a5999.I54a3f9f6480d3694e67eea1cb4f5853beace2780@changeid
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

1 files changed, 213 insertions, 3 deletions

diff --git a/drivers/net/wireless/intel/iwlwifi/mvm/scan.c b/drivers/net/wireless/intel/iwlwifi/mvm/scan.c
index 49ec515b5bad..a7ec172eeade 100644
--- a/drivers/net/wireless/intel/iwlwifi/mvm/scan.c
+++ b/drivers/net/wireless/intel/iwlwifi/mvm/scan.c
@@ -226,6 +226,14 @@ iwl_mvm_scan_type _iwl_mvm_get_scan_type(struct iwl_mvm *mvm,
 		.global_cnt = 0,
 	};
 
+	/*
+	 * A scanning AP interface probably wants to generate a survey to do
+	 * ACS (automatic channel selection).
+	 * Force a non-fragmented scan in that case.
+	 */
+	if (vif && ieee80211_vif_type_p2p(vif) == NL80211_IFTYPE_AP)
+		return IWL_SCAN_TYPE_WILD;
+
 	ieee80211_iterate_active_interfaces_atomic(mvm->hw,
 						   IEEE80211_IFACE_ITER_NORMAL,
 						   iwl_mvm_scan_iterator,
@@ -852,11 +860,13 @@ static inline bool iwl_mvm_scan_use_ebs(struct iwl_mvm *mvm,
 	 *	4. it's not a p2p find operation.
 	 *	5. we are not in low latency mode,
 	 *	   or if fragmented ebs is supported by the FW
+	 *	6. the VIF is not an AP interface (scan wants survey results)
 	 */
 	return ((capa->flags & IWL_UCODE_TLV_FLAGS_EBS_SUPPORT) &&
 		mvm->last_ebs_successful && IWL_MVM_ENABLE_EBS &&
 		vif->type != NL80211_IFTYPE_P2P_DEVICE &&
-		(!low_latency || iwl_mvm_is_frag_ebs_supported(mvm)));
+		(!low_latency || iwl_mvm_is_frag_ebs_supported(mvm)) &&
+		ieee80211_vif_type_p2p(vif) != NL80211_IFTYPE_AP);
 }
 
 static inline bool iwl_mvm_is_regular_scan(struct iwl_mvm_scan_params *params)
@@ -2124,7 +2134,8 @@ static u16 iwl_mvm_scan_umac_flags_v2(struct iwl_mvm *mvm,
 
 static u8 iwl_mvm_scan_umac_flags2(struct iwl_mvm *mvm,
 				   struct iwl_mvm_scan_params *params,
-				   struct ieee80211_vif *vif, int type)
+				   struct ieee80211_vif *vif, int type,
+				   u16 gen_flags)
 {
 	u8 flags = 0;
 
@@ -2144,6 +2155,13 @@ static u8 iwl_mvm_scan_umac_flags2(struct iwl_mvm *mvm,
 			IWL_UCODE_TLV_CAPA_SCAN_DONT_TOGGLE_ANT))
 		flags |= IWL_UMAC_SCAN_GEN_PARAMS_FLAGS2_DONT_TOGGLE_ANT;
 
+	/* Passive and AP interface -> ACS (automatic channel selection) */
+	if (gen_flags & IWL_UMAC_SCAN_GEN_FLAGS_V2_FORCE_PASSIVE &&
+	    ieee80211_vif_type_p2p(vif) == NL80211_IFTYPE_AP &&
+	    iwl_fw_lookup_notif_ver(mvm->fw, SCAN_GROUP, CHANNEL_SURVEY_NOTIF,
+				    0) >= 1)
+		flags |= IWL_UMAC_SCAN_GEN_FLAGS2_COLLECT_CHANNEL_STATS;
+
 	return flags;
 }
 
@@ -2513,7 +2531,8 @@ static int iwl_mvm_scan_umac_v14_and_above(struct iwl_mvm *mvm,
 	gen_flags = iwl_mvm_scan_umac_flags_v2(mvm, params, vif, type);
 
 	if (version >= 15)
-		gen_flags2 = iwl_mvm_scan_umac_flags2(mvm, params, vif, type);
+		gen_flags2 = iwl_mvm_scan_umac_flags2(mvm, params, vif, type,
+						      gen_flags);
 	else
 		gen_flags2 = 0;
 
@@ -3602,3 +3621,194 @@ int iwl_mvm_int_mlo_scan(struct iwl_mvm *mvm, struct ieee80211_vif *vif)
 
 	return iwl_mvm_int_mlo_scan_start(mvm, vif, channels, n_channels);
 }
+
+static int iwl_mvm_chanidx_from_phy(struct iwl_mvm *mvm,
+				    enum nl80211_band band,
+				    u16 phy_chan_num)
+{
+	struct ieee80211_supported_band *sband = mvm->hw->wiphy->bands[band];
+	int chan_idx;
+
+	if (WARN_ON_ONCE(!sband))
+		return -EINVAL;
+
+	for (chan_idx = 0; chan_idx < sband->n_channels; chan_idx++) {
+		struct ieee80211_channel *channel = &sband->channels[chan_idx];
+
+		if (channel->hw_value == phy_chan_num)
+			return chan_idx;
+	}
+
+	return -EINVAL;
+}
+
+static u32 iwl_mvm_div_by_db(u32 value, u8 db)
+{
+	/*
+	 * 2^32 * 10**(i / 10) for i = [1, 10], skipping 0 and simply stopping
+	 * at 10 dB and looping instead of using a much larger table.
+	 *
+	 * Using 64 bit math is overkill, but means the helper does not require
+	 * a limit on the input range.
+	 */
+	static const u32 db_to_val[] = {
+		0xcb59185e, 0xa1866ba8, 0x804dce7a, 0x65ea59fe, 0x50f44d89,
+		0x404de61f, 0x331426af, 0x2892c18b, 0x203a7e5b, 0x1999999a,
+	};
+
+	while (value && db > 0) {
+		u8 change = min_t(u8, db, ARRAY_SIZE(db_to_val));
+
+		value = (((u64)value) * db_to_val[change - 1]) >> 32;
+
+		db -= change;
+	}
+
+	return value;
+}
+
+VISIBLE_IF_IWLWIFI_KUNIT s8
+iwl_mvm_average_dbm_values(const struct iwl_umac_scan_channel_survey_notif *notif)
+{
+	s8 average_magnitude;
+	u32 average_factor;
+	s8 sum_magnitude = -128;
+	u32 sum_factor = 0;
+	int i, count = 0;
+
+	/*
+	 * To properly average the decibel values (signal values given in dBm)
+	 * we need to do the math in linear space.  Doing a linear average of
+	 * dB (dBm) values is a bit annoying though due to the large range of
+	 * at least -10 to -110 dBm that will not fit into a 32 bit integer.
+	 *
+	 * A 64 bit integer should be sufficient, but then we still have the
+	 * problem that there are no directly usable utility functions
+	 * available.
+	 *
+	 * So, lets not deal with that and instead do much of the calculation
+	 * with a 16.16 fixed point integer along with a base in dBm. 16.16 bit
+	 * gives us plenty of head-room for adding up a few values and even
+	 * doing some math on it. And the tail should be accurate enough too
+	 * (1/2^16 is somewhere around -48 dB, so effectively zero).
+	 *
+	 * i.e. the real value of sum is:
+	 *      sum = sum_factor / 2^16 * 10^(sum_magnitude / 10) mW
+	 *
+	 * However, that does mean we need to be able to bring two values to
+	 * a common base, so we need a helper for that.
+	 *
+	 * Note that this function takes an input with unsigned negative dBm
+	 * values but returns a signed dBm (i.e. a negative value).
+	 */
+
+	for (i = 0; i < ARRAY_SIZE(notif->noise); i++) {
+		s8 val_magnitude;
+		u32 val_factor;
+
+		if (notif->noise[i] == 0xff)
+			continue;
+
+		val_factor = 0x10000;
+		val_magnitude = -notif->noise[i];
+
+		if (val_magnitude <= sum_magnitude) {
+			u8 div_db = sum_magnitude - val_magnitude;
+
+			val_factor = iwl_mvm_div_by_db(val_factor, div_db);
+			val_magnitude = sum_magnitude;
+		} else {
+			u8 div_db = val_magnitude - sum_magnitude;
+
+			sum_factor = iwl_mvm_div_by_db(sum_factor, div_db);
+			sum_magnitude = val_magnitude;
+		}
+
+		sum_factor += val_factor;
+		count++;
+	}
+
+	/* No valid noise measurement, return a very high noise level */
+	if (count == 0)
+		return 0;
+
+	average_magnitude = sum_magnitude;
+	average_factor = sum_factor / count;
+
+	/*
+	 * average_factor will be a number smaller than 1.0 (0x10000) at this
+	 * point. What we need to do now is to adjust average_magnitude so that
+	 * average_factor is between -0.5 dB and 0.5 dB.
+	 *
+	 * Just do -1 dB steps and find the point where
+	 *   -0.5 dB * -i dB = 0x10000 * 10^(-0.5/10) / i dB
+	 *                   = div_by_db(0xe429, i)
+	 * is smaller than average_factor.
+	 */
+	for (i = 0; average_factor < iwl_mvm_div_by_db(0xe429, i); i++) {
+		/* nothing */
+	}
+
+	return average_magnitude - i;
+}
+EXPORT_SYMBOL_IF_IWLWIFI_KUNIT(iwl_mvm_average_dbm_values);
+
+void iwl_mvm_rx_channel_survey_notif(struct iwl_mvm *mvm,
+				     struct iwl_rx_cmd_buffer *rxb)
+{
+	struct iwl_rx_packet *pkt = rxb_addr(rxb);
+	const struct iwl_umac_scan_channel_survey_notif *notif =
+		(void *)pkt->data;
+	struct iwl_mvm_acs_survey_channel *info;
+	enum nl80211_band band;
+	int chan_idx;
+
+	lockdep_assert_held(&mvm->mutex);
+
+	if (!mvm->acs_survey) {
+		size_t n_channels = 0;
+
+		for (band = 0; band < NUM_NL80211_BANDS; band++) {
+			if (!mvm->hw->wiphy->bands[band])
+				continue;
+
+			n_channels += mvm->hw->wiphy->bands[band]->n_channels;
+		}
+
+		mvm->acs_survey = kzalloc(struct_size(mvm->acs_survey,
+						      channels, n_channels),
+					  GFP_KERNEL);
+
+		if (!mvm->acs_survey)
+			return;
+
+		mvm->acs_survey->n_channels = n_channels;
+		n_channels = 0;
+		for (band = 0; band < NUM_NL80211_BANDS; band++) {
+			if (!mvm->hw->wiphy->bands[band])
+				continue;
+
+			mvm->acs_survey->bands[band] =
+				&mvm->acs_survey->channels[n_channels];
+			n_channels += mvm->hw->wiphy->bands[band]->n_channels;
+		}
+	}
+
+	band = iwl_mvm_nl80211_band_from_phy(le32_to_cpu(notif->band));
+	chan_idx = iwl_mvm_chanidx_from_phy(mvm, band,
+					    le32_to_cpu(notif->channel));
+	if (WARN_ON_ONCE(chan_idx < 0))
+		return;
+
+	IWL_DEBUG_SCAN(mvm, "channel survey received for freq %d\n",
+		       mvm->hw->wiphy->bands[band]->channels[chan_idx].center_freq);
+
+	info = &mvm->acs_survey->bands[band][chan_idx];
+
+	/* Times are all in ms */
+	info->time = le32_to_cpu(notif->active_time);
+	info->time_busy = le32_to_cpu(notif->busy_time);
+	info->time_rx = le32_to_cpu(notif->rx_time);
+	info->time_tx = le32_to_cpu(notif->tx_time);
+	info->noise = iwl_mvm_average_dbm_values(notif);
+}