mac80211: Generalize off-channel operation helpers from scan code

The off-channel operations for going into power save mode (station
mode) or stop beaconing (AP/IBSS) are not limited to scanning. Move
these into a separate file and allow them to be used for other
purposes, too.

Signed-off-by: Jouni Malinen <jouni.malinen@atheros.com>
Signed-off-by: Johannes Berg <johannes@sipsolutions.net>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

net/mac80211/Makefile

@@ -6,7 +6,7 @@ mac80211-y := \
 	sta_info.o \
 	wep.o \
 	wpa.o \
-	scan.o \
+	scan.o offchannel.o \
 	ht.o agg-tx.o agg-rx.o \
 	ibss.o \
 	mlme.o work.o \

net/mac80211/ieee80211_i.h

@@ -786,7 +786,7 @@ struct ieee80211_local {
 	unsigned int wmm_acm; /* bit field of ACM bits (BIT(802.1D tag)) */
 
 	bool pspolling;
-	bool scan_ps_enabled;
+	bool offchannel_ps_enabled;
 	/*
 	 * PS can only be enabled when we have exactly one managed
 	 * interface (and monitors) in PS, this then points there.
@@ -981,6 +981,12 @@ ieee80211_rx_bss_get(struct ieee80211_local *local, u8 *bssid, int freq,
 void ieee80211_rx_bss_put(struct ieee80211_local *local,
 			  struct ieee80211_bss *bss);
 
+/* off-channel helpers */
+void ieee80211_offchannel_stop_beaconing(struct ieee80211_local *local);
+void ieee80211_offchannel_stop_station(struct ieee80211_local *local);
+void ieee80211_offchannel_return(struct ieee80211_local *local,
+				 bool enable_beaconing);
+
 /* interface handling */
 int ieee80211_iface_init(void);
 void ieee80211_iface_exit(void);

net/mac80211/offchannel.c

@@ -0,0 +1,164 @@
+/*
+ * Off-channel operation helpers
+ *
+ * Copyright 2003, Jouni Malinen <jkmaline@cc.hut.fi>
+ * Copyright 2004, Instant802 Networks, Inc.
+ * Copyright 2005, Devicescape Software, Inc.
+ * Copyright 2006-2007	Jiri Benc <jbenc@suse.cz>
+ * Copyright 2007, Michael Wu <flamingice@sourmilk.net>
+ * Copyright 2009	Johannes Berg <johannes@sipsolutions.net>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+#include <net/mac80211.h>
+#include "ieee80211_i.h"
+
+/*
+ * inform AP that we will go to sleep so that it will buffer the frames
+ * while we scan
+ */
+static void ieee80211_offchannel_ps_enable(struct ieee80211_sub_if_data *sdata)
+{
+	struct ieee80211_local *local = sdata->local;
+
+	local->offchannel_ps_enabled = false;
+
+	/* FIXME: what to do when local->pspolling is true? */
+
+	del_timer_sync(&local->dynamic_ps_timer);
+	cancel_work_sync(&local->dynamic_ps_enable_work);
+
+	if (local->hw.conf.flags & IEEE80211_CONF_PS) {
+		local->offchannel_ps_enabled = true;
+		local->hw.conf.flags &= ~IEEE80211_CONF_PS;
+		ieee80211_hw_config(local, IEEE80211_CONF_CHANGE_PS);
+	}
+
+	if (!(local->offchannel_ps_enabled) ||
+	    !(local->hw.flags & IEEE80211_HW_PS_NULLFUNC_STACK))
+		/*
+		 * If power save was enabled, no need to send a nullfunc
+		 * frame because AP knows that we are sleeping. But if the
+		 * hardware is creating the nullfunc frame for power save
+		 * status (ie. IEEE80211_HW_PS_NULLFUNC_STACK is not
+		 * enabled) and power save was enabled, the firmware just
+		 * sent a null frame with power save disabled. So we need
+		 * to send a new nullfunc frame to inform the AP that we
+		 * are again sleeping.
+		 */
+		ieee80211_send_nullfunc(local, sdata, 1);
+}
+
+/* inform AP that we are awake again, unless power save is enabled */
+static void ieee80211_offchannel_ps_disable(struct ieee80211_sub_if_data *sdata)
+{
+	struct ieee80211_local *local = sdata->local;
+
+	if (!local->ps_sdata)
+		ieee80211_send_nullfunc(local, sdata, 0);
+	else if (local->offchannel_ps_enabled) {
+		/*
+		 * In !IEEE80211_HW_PS_NULLFUNC_STACK case the hardware
+		 * will send a nullfunc frame with the powersave bit set
+		 * even though the AP already knows that we are sleeping.
+		 * This could be avoided by sending a null frame with power
+		 * save bit disabled before enabling the power save, but
+		 * this doesn't gain anything.
+		 *
+		 * When IEEE80211_HW_PS_NULLFUNC_STACK is enabled, no need
+		 * to send a nullfunc frame because AP already knows that
+		 * we are sleeping, let's just enable power save mode in
+		 * hardware.
+		 */
+		local->hw.conf.flags |= IEEE80211_CONF_PS;
+		ieee80211_hw_config(local, IEEE80211_CONF_CHANGE_PS);
+	} else if (local->hw.conf.dynamic_ps_timeout > 0) {
+		/*
+		 * If IEEE80211_CONF_PS was not set and the dynamic_ps_timer
+		 * had been running before leaving the operating channel,
+		 * restart the timer now and send a nullfunc frame to inform
+		 * the AP that we are awake.
+		 */
+		ieee80211_send_nullfunc(local, sdata, 0);
+		mod_timer(&local->dynamic_ps_timer, jiffies +
+			  msecs_to_jiffies(local->hw.conf.dynamic_ps_timeout));
+	}
+}
+
+void ieee80211_offchannel_stop_beaconing(struct ieee80211_local *local)
+{
+	struct ieee80211_sub_if_data *sdata;
+
+	mutex_lock(&local->iflist_mtx);
+	list_for_each_entry(sdata, &local->interfaces, list) {
+		if (!ieee80211_sdata_running(sdata))
+			continue;
+
+		/* disable beaconing */
+		if (sdata->vif.type == NL80211_IFTYPE_AP ||
+		    sdata->vif.type == NL80211_IFTYPE_ADHOC ||
+		    sdata->vif.type == NL80211_IFTYPE_MESH_POINT)
+			ieee80211_bss_info_change_notify(
+				sdata, BSS_CHANGED_BEACON_ENABLED);
+
+		/*
+		 * only handle non-STA interfaces here, STA interfaces
+		 * are handled in ieee80211_offchannel_stop_station(),
+		 * e.g., from the background scan state machine
+		 */
+		if (sdata->vif.type != NL80211_IFTYPE_STATION)
+			netif_stop_queue(sdata->dev);
+	}
+	mutex_unlock(&local->iflist_mtx);
+}
+
+void ieee80211_offchannel_stop_station(struct ieee80211_local *local)
+{
+	struct ieee80211_sub_if_data *sdata;
+
+	/*
+	 * notify the AP about us leaving the channel and stop all STA interfaces
+	 */
+	mutex_lock(&local->iflist_mtx);
+	list_for_each_entry(sdata, &local->interfaces, list) {
+		if (!ieee80211_sdata_running(sdata))
+			continue;
+
+		if (sdata->vif.type == NL80211_IFTYPE_STATION) {
+			netif_stop_queue(sdata->dev);
+			if (sdata->u.mgd.associated)
+				ieee80211_offchannel_ps_enable(sdata);
+		}
+	}
+	mutex_unlock(&local->iflist_mtx);
+}
+
+void ieee80211_offchannel_return(struct ieee80211_local *local,
+				 bool enable_beaconing)
+{
+	struct ieee80211_sub_if_data *sdata;
+
+	mutex_lock(&local->iflist_mtx);
+	list_for_each_entry(sdata, &local->interfaces, list) {
+		if (!ieee80211_sdata_running(sdata))
+			continue;
+
+		/* Tell AP we're back */
+		if (sdata->vif.type == NL80211_IFTYPE_STATION) {
+			if (sdata->u.mgd.associated)
+				ieee80211_offchannel_ps_disable(sdata);
+			netif_wake_queue(sdata->dev);
+		}
+
+		/* re-enable beaconing */
+		if (enable_beaconing &&
+		    (sdata->vif.type == NL80211_IFTYPE_AP ||
+		     sdata->vif.type == NL80211_IFTYPE_ADHOC ||
+		     sdata->vif.type == NL80211_IFTYPE_MESH_POINT))
+			ieee80211_bss_info_change_notify(
+				sdata, BSS_CHANGED_BEACON_ENABLED);
+	}
+	mutex_unlock(&local->iflist_mtx);
+}