mac80211: Add support for connection monitor in hardware

This patch is based on a RFC patch by Kalle Valo.

The wl1271 has a feature which handles the connection monitor logic
in hardware, basically sending periodically nullfunc frames and reporting
to the host if AP is lost, after attempting to recover by sending
probe-requests to the AP.

Add support to mac80211 by adding a new flag IEEE80211_HW_CONNECTION_MONITOR
which prevents conn_mon_timer from triggering during idle periods, and
prevents sending probe-requests to the AP if beacon-loss is indicated by the
hardware.

Cc: Kalle Valo <kalle.valo@nokia.com>
Signed-off-by: Juuso Oikarinen <juuso.oikarinen@nokia.com>
Reviewed-by: Johannes Berg <johannes@sipsolutions.net>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

include/net/mac80211.h

@@ -954,6 +954,11 @@ enum ieee80211_tkip_key_type {
  *	Hardware can provide ack status reports of Tx frames to
  *	the stack.
  *
+ * @IEEE80211_HW_CONNECTION_MONITOR:
+ *      The hardware performs its own connection monitoring, including
+ *      periodic keep-alives to the AP and probing the AP on beacon loss.
+ *      When this flag is set, signaling beacon-loss will cause an immediate
+ *      change to disassociated state.
  */
 enum ieee80211_hw_flags {
 	IEEE80211_HW_HAS_RATE_CONTROL			= 1<<0,
@@ -975,6 +980,7 @@ enum ieee80211_hw_flags {
 	IEEE80211_HW_SUPPORTS_DYNAMIC_SMPS		= 1<<16,
 	IEEE80211_HW_SUPPORTS_UAPSD			= 1<<17,
 	IEEE80211_HW_REPORTS_TX_ACK_STATUS		= 1<<18,
+	IEEE80211_HW_CONNECTION_MONITOR			= 1<<19,
 };
 
 /**
@@ -2364,12 +2370,26 @@ void ieee80211_sta_block_awake(struct ieee80211_hw *hw,
  *
  * @vif: &struct ieee80211_vif pointer from the add_interface callback.
  *
- * When beacon filtering is enabled with IEEE80211_HW_BEACON_FILTERING and
- * IEEE80211_CONF_PS is set, the driver needs to inform whenever the
+ * When beacon filtering is enabled with %IEEE80211_HW_BEACON_FILTERING and
+ * %IEEE80211_CONF_PS is set, the driver needs to inform whenever the
  * hardware is not receiving beacons with this function.
  */
 void ieee80211_beacon_loss(struct ieee80211_vif *vif);
 
+/**
+ * ieee80211_connection_loss - inform hardware has lost connection to the AP
+ *
+ * @vif: &struct ieee80211_vif pointer from the add_interface callback.
+ *
+ * When beacon filtering is enabled with %IEEE80211_HW_BEACON_FILTERING, and
+ * %IEEE80211_CONF_PS and %IEEE80211_HW_CONNECTION_MONITOR are set, the driver
+ * needs to inform if the connection to the AP has been lost.
+ *
+ * This function will cause immediate change to disassociated state,
+ * without connection recovery attempts.
+ */
+void ieee80211_connection_loss(struct ieee80211_vif *vif);
+
 /* Rate control API */
 
 /**

net/mac80211/ieee80211_i.h

@@ -327,7 +327,7 @@ struct ieee80211_if_managed {
 	struct work_struct work;
 	struct work_struct monitor_work;
 	struct work_struct chswitch_work;
-	struct work_struct beacon_loss_work;
+	struct work_struct beacon_connection_loss_work;
 
 	unsigned long probe_timeout;
 	int probe_send_count;
@@ -1156,7 +1156,7 @@ void ieee80211_send_nullfunc(struct ieee80211_local *local,
 			     int powersave);
 void ieee80211_sta_rx_notify(struct ieee80211_sub_if_data *sdata,
 			     struct ieee80211_hdr *hdr);
-void ieee80211_beacon_loss_work(struct work_struct *work);
+void ieee80211_beacon_connection_loss_work(struct work_struct *work);
 
 void ieee80211_wake_queues_by_reason(struct ieee80211_hw *hw,
 				     enum queue_stop_reason reason);

net/mac80211/iface.c

@@ -486,7 +486,7 @@ static int ieee80211_stop(struct net_device *dev)
 		cancel_work_sync(&sdata->u.mgd.work);
 		cancel_work_sync(&sdata->u.mgd.chswitch_work);
 		cancel_work_sync(&sdata->u.mgd.monitor_work);
-		cancel_work_sync(&sdata->u.mgd.beacon_loss_work);
+		cancel_work_sync(&sdata->u.mgd.beacon_connection_loss_work);
 
 		/*
 		 * When we get here, the interface is marked down.

net/mac80211/mlme.c

@@ -851,6 +851,9 @@ void ieee80211_sta_rx_notify(struct ieee80211_sub_if_data *sdata,
 	if (is_multicast_ether_addr(hdr->addr1))
 		return;
 
+	if (sdata->local->hw.flags & IEEE80211_HW_CONNECTION_MONITOR)
+		return;
+
 	mod_timer(&sdata->u.mgd.conn_mon_timer,
 		  round_jiffies_up(jiffies + IEEE80211_CONNECTION_IDLE_TIME));
 }
@@ -928,23 +931,68 @@ static void ieee80211_mgd_probe_ap(struct ieee80211_sub_if_data *sdata,
 	mutex_unlock(&ifmgd->mtx);
 }
 
-void ieee80211_beacon_loss_work(struct work_struct *work)
+static void __ieee80211_connection_loss(struct ieee80211_sub_if_data *sdata)
+{
+	struct ieee80211_if_managed *ifmgd = &sdata->u.mgd;
+	struct ieee80211_local *local = sdata->local;
+	u8 bssid[ETH_ALEN];
+
+	mutex_lock(&ifmgd->mtx);
+	if (!ifmgd->associated) {
+		mutex_unlock(&ifmgd->mtx);
+		return;
+	}
+
+	memcpy(bssid, ifmgd->associated->bssid, ETH_ALEN);
+
+	printk(KERN_DEBUG "Connection to AP %pM lost.\n", bssid);
+
+	ieee80211_set_disassoc(sdata);
+	ieee80211_recalc_idle(local);
+	mutex_unlock(&ifmgd->mtx);
+	/*
+	 * must be outside lock due to cfg80211,
+	 * but that's not a problem.
+	 */
+	ieee80211_send_deauth_disassoc(sdata, bssid,
+				       IEEE80211_STYPE_DEAUTH,
+				       WLAN_REASON_DISASSOC_DUE_TO_INACTIVITY,
+				       NULL);
+}
+
+void ieee80211_beacon_connection_loss_work(struct work_struct *work)
 {
 	struct ieee80211_sub_if_data *sdata =
 		container_of(work, struct ieee80211_sub_if_data,
-			     u.mgd.beacon_loss_work);
+			     u.mgd.beacon_connection_loss_work);
 
-	ieee80211_mgd_probe_ap(sdata, true);
+	if (sdata->local->hw.flags & IEEE80211_HW_CONNECTION_MONITOR)
+		__ieee80211_connection_loss(sdata);
+	else
+		ieee80211_mgd_probe_ap(sdata, true);
 }
 
 void ieee80211_beacon_loss(struct ieee80211_vif *vif)
 {
 	struct ieee80211_sub_if_data *sdata = vif_to_sdata(vif);
+	struct ieee80211_hw *hw = &sdata->local->hw;
 
-	ieee80211_queue_work(&sdata->local->hw, &sdata->u.mgd.beacon_loss_work);
+	WARN_ON(hw->flags & IEEE80211_HW_CONNECTION_MONITOR);
+	ieee80211_queue_work(hw, &sdata->u.mgd.beacon_connection_loss_work);
 }
 EXPORT_SYMBOL(ieee80211_beacon_loss);
 
+void ieee80211_connection_loss(struct ieee80211_vif *vif)
+{
+	struct ieee80211_sub_if_data *sdata = vif_to_sdata(vif);
+	struct ieee80211_hw *hw = &sdata->local->hw;
+
+	WARN_ON(!(hw->flags & IEEE80211_HW_CONNECTION_MONITOR));
+	ieee80211_queue_work(hw, &sdata->u.mgd.beacon_connection_loss_work);
+}
+EXPORT_SYMBOL(ieee80211_connection_loss);
+
+
 static enum rx_mgmt_action __must_check
 ieee80211_rx_mgmt_deauth(struct ieee80211_sub_if_data *sdata,
 			 struct ieee80211_mgmt *mgmt, size_t len)
@@ -1634,7 +1682,8 @@ static void ieee80211_sta_bcn_mon_timer(unsigned long data)
 	if (local->quiescing)
 		return;
 
-	ieee80211_queue_work(&sdata->local->hw, &sdata->u.mgd.beacon_loss_work);
+	ieee80211_queue_work(&sdata->local->hw,
+			     &sdata->u.mgd.beacon_connection_loss_work);
 }
 
 static void ieee80211_sta_conn_mon_timer(unsigned long data)
@@ -1686,7 +1735,7 @@ void ieee80211_sta_quiesce(struct ieee80211_sub_if_data *sdata)
 	 */
 
 	cancel_work_sync(&ifmgd->work);
-	cancel_work_sync(&ifmgd->beacon_loss_work);
+	cancel_work_sync(&ifmgd->beacon_connection_loss_work);
 	if (del_timer_sync(&ifmgd->timer))
 		set_bit(TMR_RUNNING_TIMER, &ifmgd->timers_running);
 
@@ -1720,7 +1769,8 @@ void ieee80211_sta_setup_sdata(struct ieee80211_sub_if_data *sdata)
 	INIT_WORK(&ifmgd->work, ieee80211_sta_work);
 	INIT_WORK(&ifmgd->monitor_work, ieee80211_sta_monitor_work);
 	INIT_WORK(&ifmgd->chswitch_work, ieee80211_chswitch_work);
-	INIT_WORK(&ifmgd->beacon_loss_work, ieee80211_beacon_loss_work);
+	INIT_WORK(&ifmgd->beacon_connection_loss_work,
+		  ieee80211_beacon_connection_loss_work);
 	setup_timer(&ifmgd->timer, ieee80211_sta_timer,
 		    (unsigned long) sdata);
 	setup_timer(&ifmgd->bcn_mon_timer, ieee80211_sta_bcn_mon_timer,