mac80211: introduce beacon-only timing data

In order to be able to predict the next DTIM TBTT
in the driver, add the ability to use timing data
from beacons only with the new hardware flag
IEEE80211_HW_TIMING_BEACON_ONLY and the BSS info
value sync_dtim_count which is only valid if the
timing data came from a beacon. The data can only
come from a beacon, and if no beacon was received
before association it is updated later together
with the DTIM count notification.

Signed-off-by: Johannes Berg <johannes.berg@intel.com>

4 files changed, 68 insertions, 6 deletions

diff --git a/net/mac80211/ieee80211_i.h b/net/mac80211/ieee80211_i.h
index 8e884fc..d794856 100644
--- a/net/mac80211/ieee80211_i.h
+++ b/net/mac80211/ieee80211_i.h
@@ -86,7 +86,7 @@ struct ieee80211_fragment_entry {
 
 
 struct ieee80211_bss {
-	u32 device_ts;
+	u32 device_ts_beacon, device_ts_presp;
 
 	bool wmm_used;
 	bool uapsd_supported;
diff --git a/net/mac80211/mlme.c b/net/mac80211/mlme.c
index 51eca5a..a29d09c 100644
--- a/net/mac80211/mlme.c
+++ b/net/mac80211/mlme.c
@@ -2567,6 +2567,17 @@ static void ieee80211_rx_mgmt_beacon(struct ieee80211_sub_if_data *sdata,
 		ieee80211_rx_bss_info(sdata, mgmt, len, rx_status, &elems);
 		ifmgd->assoc_data->have_beacon = true;
 		ifmgd->assoc_data->need_beacon = false;
+		if (local->hw.flags & IEEE80211_HW_TIMING_BEACON_ONLY) {
+			sdata->vif.bss_conf.sync_tsf =
+				le64_to_cpu(mgmt->u.beacon.timestamp);
+			sdata->vif.bss_conf.sync_device_ts =
+				rx_status->device_timestamp;
+			if (elems.tim)
+				sdata->vif.bss_conf.sync_dtim_count =
+					elems.tim->dtim_count;
+			else
+				sdata->vif.bss_conf.sync_dtim_count = 0;
+		}
 		/* continue assoc process */
 		ifmgd->assoc_data->timeout = jiffies;
 		run_again(ifmgd, ifmgd->assoc_data->timeout);
@@ -2725,7 +2736,7 @@ static void ieee80211_rx_mgmt_beacon(struct ieee80211_sub_if_data *sdata,
 
 	/*
 	 * If we haven't had a beacon before, tell the driver about the
-	 * DTIM period now.
+	 * DTIM period (and beacon timing if desired) now.
 	 */
 	if (!bss_conf->dtim_period) {
 		/* a few bogus AP send dtim_period = 0 or no TIM IE */
@@ -2733,6 +2744,19 @@ static void ieee80211_rx_mgmt_beacon(struct ieee80211_sub_if_data *sdata,
 			bss_conf->dtim_period = elems.tim->dtim_period ?: 1;
 		else
 			bss_conf->dtim_period = 1;
+
+		if (local->hw.flags & IEEE80211_HW_TIMING_BEACON_ONLY) {
+			sdata->vif.bss_conf.sync_tsf =
+				le64_to_cpu(mgmt->u.beacon.timestamp);
+			sdata->vif.bss_conf.sync_device_ts =
+				rx_status->device_timestamp;
+			if (elems.tim)
+				sdata->vif.bss_conf.sync_dtim_count =
+					elems.tim->dtim_count;
+			else
+				sdata->vif.bss_conf.sync_dtim_count = 0;
+		}
+
 		changed |= BSS_CHANGED_DTIM_PERIOD;
 	}
 
@@ -3712,10 +3736,33 @@ static int ieee80211_prep_connection(struct ieee80211_sub_if_data *sdata,
 		/* set timing information */
 		sdata->vif.bss_conf.beacon_int = cbss->beacon_interval;
 		rcu_read_lock();
-		ies = rcu_dereference(cbss->ies);
-		sdata->vif.bss_conf.sync_tsf = ies->tsf;
+		ies = rcu_dereference(cbss->beacon_ies);
+		if (ies) {
+			const u8 *tim_ie;
+
+			sdata->vif.bss_conf.sync_tsf = ies->tsf;
+			sdata->vif.bss_conf.sync_device_ts =
+				bss->device_ts_beacon;
+			tim_ie = cfg80211_find_ie(WLAN_EID_TIM,
+						  ies->data, ies->len);
+			if (tim_ie && tim_ie[1] >= 2)
+				sdata->vif.bss_conf.sync_dtim_count = tim_ie[2];
+			else
+				sdata->vif.bss_conf.sync_dtim_count = 0;
+		} else if (!(local->hw.flags &
+					IEEE80211_HW_TIMING_BEACON_ONLY)) {
+			ies = rcu_dereference(cbss->proberesp_ies);
+			/* must be non-NULL since beacon IEs were NULL */
+			sdata->vif.bss_conf.sync_tsf = ies->tsf;
+			sdata->vif.bss_conf.sync_device_ts =
+				bss->device_ts_presp;
+			sdata->vif.bss_conf.sync_dtim_count = 0;
+		} else {
+			sdata->vif.bss_conf.sync_tsf = 0;
+			sdata->vif.bss_conf.sync_device_ts = 0;
+			sdata->vif.bss_conf.sync_dtim_count = 0;
+		}
 		rcu_read_unlock();
-		sdata->vif.bss_conf.sync_device_ts = bss->device_ts;
 
 		/* tell driver about BSSID, basic rates and timing */
 		ieee80211_bss_info_change_notify(sdata,
@@ -4041,13 +4088,23 @@ int ieee80211_mgd_assoc(struct ieee80211_sub_if_data *sdata,
 		const u8 *tim_ie = cfg80211_find_ie(WLAN_EID_TIM,
 						    beacon_ies->data,
 						    beacon_ies->len);
+		u8 dtim_count = 0;
+
 		if (tim_ie && tim_ie[1] >= sizeof(struct ieee80211_tim_ie)) {
 			const struct ieee80211_tim_ie *tim;
 			tim = (void *)(tim_ie + 2);
 			ifmgd->dtim_period = tim->dtim_period;
+			dtim_count = tim->dtim_count;
 		}
 		assoc_data->have_beacon = true;
 		assoc_data->timeout = jiffies;
+
+		if (local->hw.flags & IEEE80211_HW_TIMING_BEACON_ONLY) {
+			sdata->vif.bss_conf.sync_tsf = beacon_ies->tsf;
+			sdata->vif.bss_conf.sync_device_ts =
+				bss->device_ts_beacon;
+			sdata->vif.bss_conf.sync_dtim_count = dtim_count;
+		}
 	} else {
 		assoc_data->timeout = jiffies;
 	}
diff --git a/net/mac80211/scan.c b/net/mac80211/scan.c
index 400153f..edd47d9 100644
--- a/net/mac80211/scan.c
+++ b/net/mac80211/scan.c
@@ -80,7 +80,10 @@ ieee80211_bss_info_update(struct ieee80211_local *local,
 
 	bss = (void *)cbss->priv;
 
-	bss->device_ts = rx_status->device_timestamp;
+	if (beacon)
+		bss->device_ts_beacon = rx_status->device_timestamp;
+	else
+		bss->device_ts_presp = rx_status->device_timestamp;
 
 	if (elems->parse_error) {
 		if (beacon)
diff --git a/net/mac80211/trace.h b/net/mac80211/trace.h
index a2ca72c..0bdd7ae 100644
--- a/net/mac80211/trace.h
+++ b/net/mac80211/trace.h
@@ -340,6 +340,7 @@ TRACE_EVENT(drv_bss_info_changed,
 		__field(u16, assoc_cap)
 		__field(u64, sync_tsf)
 		__field(u32, sync_device_ts)
+		__field(u8, sync_dtim_count)
 		__field(u32, basic_rates)
 		__array(int, mcast_rate, IEEE80211_NUM_BANDS)
 		__field(u16, ht_operation_mode)
@@ -379,6 +380,7 @@ TRACE_EVENT(drv_bss_info_changed,
 		__entry->assoc_cap = info->assoc_capability;
 		__entry->sync_tsf = info->sync_tsf;
 		__entry->sync_device_ts = info->sync_device_ts;
+		__entry->sync_dtim_count = info->sync_dtim_count;
 		__entry->basic_rates = info->basic_rates;
 		memcpy(__entry->mcast_rate, info->mcast_rate,
 		       sizeof(__entry->mcast_rate));