ath9k: Fix beacon configuration for addition/removal of interfaces

This patch fixes some issues with interface reconfiguration. It could
for example happen that an AP interface in beacon slot 0 was removed
leaving an IBSS station in one of the other slots. When this happens
the driver never sends out the beacon as it only tries to send a beacon
from slot 0.

Appart from that the tracking of required changes to the beacon config is
relatively complicated and prone to errors.

The approach taken here is to solve reconfiguration issues is to
reconfigure the beacons when any interface changes. This means that
the complexity of deciding whether an interface change may modify the
beacon configuration is gone. It also means that the beacon config will
be reliably updated when an interface is removed.

The issue that a single non-AP interface might not be in beacon
slot 0 and wouldn't be send out is solved by moving it into the
first slot. The TSF value in hardware is adjusted accordingly so
that the timestamp of the beacons stay consistent.
Signed-off-by: Benjamin Berg <benjamin.berg@open-mesh.com>
Signed-off-by: Kalle Valo <kvalo@qca.qualcomm.com>

drivers/net/wireless/ath/ath9k/ath9k.h

@@ -637,6 +637,8 @@ struct ath9k_vif_iter_data {
 	int nwds;      /* number of WDS vifs */
 	int nadhocs;   /* number of adhoc vifs */
 	int nocbs;     /* number of OCB vifs */
+	int nbcnvifs;  /* number of beaconing vifs */
+	struct ieee80211_vif *primary_beacon_vif;
 	struct ieee80211_vif *primary_sta;
 };
 
@@ -685,10 +687,11 @@ struct ath_beacon {
 };
 
 void ath9k_beacon_tasklet(unsigned long data);
-void ath9k_beacon_config(struct ath_softc *sc, struct ieee80211_vif *vif,
-			 u32 changed);
+void ath9k_beacon_config(struct ath_softc *sc, struct ieee80211_vif *main_vif,
+			 bool beacons);
 void ath9k_beacon_assign_slot(struct ath_softc *sc, struct ieee80211_vif *vif);
 void ath9k_beacon_remove_slot(struct ath_softc *sc, struct ieee80211_vif *vif);
+void ath9k_beacon_ensure_primary_slot(struct ath_softc *sc);
 void ath9k_set_beacon(struct ath_softc *sc);
 bool ath9k_csa_is_finished(struct ath_softc *sc, struct ieee80211_vif *vif);
 void ath9k_csa_update(struct ath_softc *sc);

drivers/net/wireless/ath/ath9k/common.h

@@ -50,6 +50,7 @@
 #define IEEE80211_MS_TO_TU(x)   (((x) * 1000) / 1024)
 
 struct ath_beacon_config {
+	struct ieee80211_vif *main_vif;
 	int beacon_interval;
 	u16 dtim_period;
 	u16 bmiss_timeout;

drivers/net/wireless/ath/ath9k/main.c

@@ -910,6 +910,22 @@ static bool ath9k_uses_beacons(int type)
 	}
 }
 
+static void ath9k_vif_iter_set_beacon(struct ath9k_vif_iter_data *iter_data,
+				      struct ieee80211_vif *vif)
+{
+	/* Use the first (configured) interface, but prefering AP interfaces. */
+	if (!iter_data->primary_beacon_vif) {
+		iter_data->primary_beacon_vif = vif;
+	} else {
+		if (iter_data->primary_beacon_vif->type != NL80211_IFTYPE_AP &&
+		    vif->type == NL80211_IFTYPE_AP)
+		iter_data->primary_beacon_vif = vif;
+	}
+
+	iter_data->beacons = true;
+	iter_data->nbcnvifs += 1;
+}
+
 static void ath9k_vif_iter(struct ath9k_vif_iter_data *iter_data,
 			   u8 *mac, struct ieee80211_vif *vif)
 {
@@ -931,6 +947,8 @@ static void ath9k_vif_iter(struct ath9k_vif_iter_data *iter_data,
 	switch (vif->type) {
 	case NL80211_IFTYPE_AP:
 		iter_data->naps++;
+		if (vif->bss_conf.enable_beacon)
+			ath9k_vif_iter_set_beacon(iter_data, vif);
 		break;
 	case NL80211_IFTYPE_STATION:
 		iter_data->nstations++;
@@ -943,12 +961,12 @@ static void ath9k_vif_iter(struct ath9k_vif_iter_data *iter_data,
 	case NL80211_IFTYPE_ADHOC:
 		iter_data->nadhocs++;
 		if (vif->bss_conf.enable_beacon)
-			iter_data->beacons = true;
+			ath9k_vif_iter_set_beacon(iter_data, vif);
 		break;
 	case NL80211_IFTYPE_MESH_POINT:
 		iter_data->nmeshes++;
 		if (vif->bss_conf.enable_beacon)
-			iter_data->beacons = true;
+			ath9k_vif_iter_set_beacon(iter_data, vif);
 		break;
 	case NL80211_IFTYPE_WDS:
 		iter_data->nwds++;
@@ -1081,7 +1099,6 @@ void ath9k_calculate_summary_state(struct ath_softc *sc,
 	struct ath_hw *ah = sc->sc_ah;
 	struct ath_common *common = ath9k_hw_common(ah);
 	struct ath9k_vif_iter_data iter_data;
-	struct ath_beacon_config *cur_conf;
 
 	ath_chanctx_check_active(sc, ctx);
 
@@ -1103,13 +1120,12 @@ void ath9k_calculate_summary_state(struct ath_softc *sc,
 	ath_hw_setbssidmask(common);
 
 	if (iter_data.naps > 0) {
-		cur_conf = &ctx->beacon;
 		ath9k_hw_set_tsfadjust(ah, true);
 		ah->opmode = NL80211_IFTYPE_AP;
-		if (cur_conf->enable_beacon)
-			iter_data.beacons = true;
 	} else {
 		ath9k_hw_set_tsfadjust(ah, false);
+		if (iter_data.beacons)
+			ath9k_beacon_ensure_primary_slot(sc);
 
 		if (iter_data.nmeshes)
 			ah->opmode = NL80211_IFTYPE_MESH_POINT;
@@ -1134,7 +1150,6 @@ void ath9k_calculate_summary_state(struct ath_softc *sc,
 			ctx->switch_after_beacon = true;
 	}
 
-	ah->imask &= ~ATH9K_INT_SWBA;
 	if (ah->opmode == NL80211_IFTYPE_STATION) {
 		bool changed = (iter_data.primary_sta != ctx->primary_sta);
 
@@ -1151,16 +1166,12 @@ void ath9k_calculate_summary_state(struct ath_softc *sc,
 			if (ath9k_hw_mci_is_enabled(sc->sc_ah))
 				ath9k_mci_update_wlan_channels(sc, true);
 		}
-	} else if (iter_data.beacons) {
-		ah->imask |= ATH9K_INT_SWBA;
 	}
+	sc->nbcnvifs = iter_data.nbcnvifs;
+	ath9k_beacon_config(sc, iter_data.primary_beacon_vif,
+			    iter_data.beacons);
 	ath9k_hw_set_interrupts(ah);
 
-	if (iter_data.beacons)
-		set_bit(ATH_OP_BEACONS, &common->op_flags);
-	else
-		clear_bit(ATH_OP_BEACONS, &common->op_flags);
-
 	if (ah->slottime != iter_data.slottime) {
 		ah->slottime = iter_data.slottime;
 		ath9k_hw_init_global_settings(ah);
@@ -1777,9 +1788,7 @@ static void ath9k_bss_info_changed(struct ieee80211_hw *hw,
 	if ((changed & BSS_CHANGED_BEACON_ENABLED) ||
 	    (changed & BSS_CHANGED_BEACON_INT) ||
 	    (changed & BSS_CHANGED_BEACON_INFO)) {
-		ath9k_beacon_config(sc, vif, changed);
-		if (changed & BSS_CHANGED_BEACON_ENABLED)
-			ath9k_calculate_summary_state(sc, avp->chanctx);
+		ath9k_calculate_summary_state(sc, avp->chanctx);
 	}
 
 	if ((avp->chanctx == sc->cur_chan) &&