mac80211: add command to get current rssi

Get current rssi (in dBm) from the driver/FW.

Instead of reporting the signal received in the last
rx packet, which might be inaccurate if rx traffic is
low and beacon filtering is enabled, get the signal
from the driver/FW.

Signed-off-by: Victor Goldenshtein <victorg@ti.com>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

include/net/mac80211.h

@@ -2249,6 +2249,9 @@ enum ieee80211_rate_control_changed {
  * @get_et_strings:  Ethtool API to get a set of strings to describe stats
  *	and perhaps other supported types of ethtool data-sets.
  *
+ * @get_rssi: Get current signal strength in dBm, the function is optional
+ *	and can sleep.
+ *
  */
 struct ieee80211_ops {
 	void (*tx)(struct ieee80211_hw *hw, struct sk_buff *skb);
@@ -2388,6 +2391,8 @@ struct ieee80211_ops {
 	void	(*get_et_strings)(struct ieee80211_hw *hw,
 				  struct ieee80211_vif *vif,
 				  u32 sset, u8 *data);
+	int	(*get_rssi)(struct ieee80211_hw *hw, struct ieee80211_vif *vif,
+			    struct ieee80211_sta *sta, s8 *rssi_dbm);
 };
 
 /**

net/mac80211/cfg.c

@@ -353,6 +353,7 @@ void sta_set_rate_info_tx(struct sta_info *sta,
 static void sta_set_sinfo(struct sta_info *sta, struct station_info *sinfo)
 {
 	struct ieee80211_sub_if_data *sdata = sta->sdata;
+	struct ieee80211_local *local = sdata->local;
 	struct timespec uptime;
 
 	sinfo->generation = sdata->local->sta_generation;
@@ -388,7 +389,9 @@ static void sta_set_sinfo(struct sta_info *sta, struct station_info *sinfo)
 	if ((sta->local->hw.flags & IEEE80211_HW_SIGNAL_DBM) ||
 	    (sta->local->hw.flags & IEEE80211_HW_SIGNAL_UNSPEC)) {
 		sinfo->filled |= STATION_INFO_SIGNAL | STATION_INFO_SIGNAL_AVG;
-		sinfo->signal = (s8)sta->last_signal;
+		if (!local->ops->get_rssi ||
+		    drv_get_rssi(local, sdata, &sta->sta, &sinfo->signal))
+			sinfo->signal = (s8)sta->last_signal;
 		sinfo->signal_avg = (s8) -ewma_read(&sta->avg_signal);
 	}
 
@@ -517,7 +520,7 @@ static void ieee80211_get_et_stats(struct wiphy *wiphy,
 	 * network device.
 	 */
 
-	rcu_read_lock();
+	mutex_lock(&local->sta_mtx);
 
 	if (sdata->vif.type == NL80211_IFTYPE_STATION) {
 		sta = sta_info_get_bss(sdata, sdata->u.mgd.bssid);
@@ -546,7 +549,7 @@ static void ieee80211_get_et_stats(struct wiphy *wiphy,
 			data[i] = (u8)sinfo.signal_avg;
 		i++;
 	} else {
-		list_for_each_entry_rcu(sta, &local->sta_list, list) {
+		list_for_each_entry(sta, &local->sta_list, list) {
 			/* Make sure this station belongs to the proper dev */
 			if (sta->sdata->dev != dev)
 				continue;
@@ -603,7 +606,7 @@ do_survey:
 	else
 		data[i++] = -1LL;
 
-	rcu_read_unlock();
+	mutex_unlock(&local->sta_mtx);
 
 	if (WARN_ON(i != STA_STATS_LEN))
 		return;
@@ -629,10 +632,11 @@ static int ieee80211_dump_station(struct wiphy *wiphy, struct net_device *dev,
 				 int idx, u8 *mac, struct station_info *sinfo)
 {
 	struct ieee80211_sub_if_data *sdata = IEEE80211_DEV_TO_SUB_IF(dev);
+	struct ieee80211_local *local = sdata->local;
 	struct sta_info *sta;
 	int ret = -ENOENT;
 
-	rcu_read_lock();
+	mutex_lock(&local->sta_mtx);
 
 	sta = sta_info_get_by_idx(sdata, idx);
 	if (sta) {
@@ -641,7 +645,7 @@ static int ieee80211_dump_station(struct wiphy *wiphy, struct net_device *dev,
 		sta_set_sinfo(sta, sinfo);
 	}
 
-	rcu_read_unlock();
+	mutex_unlock(&local->sta_mtx);
 
 	return ret;
 }
@@ -658,10 +662,11 @@ static int ieee80211_get_station(struct wiphy *wiphy, struct net_device *dev,
 				 u8 *mac, struct station_info *sinfo)
 {
 	struct ieee80211_sub_if_data *sdata = IEEE80211_DEV_TO_SUB_IF(dev);
+	struct ieee80211_local *local = sdata->local;
 	struct sta_info *sta;
 	int ret = -ENOENT;
 
-	rcu_read_lock();
+	mutex_lock(&local->sta_mtx);
 
 	sta = sta_info_get_bss(sdata, mac);
 	if (sta) {
@@ -669,7 +674,7 @@ static int ieee80211_get_station(struct wiphy *wiphy, struct net_device *dev,
 		sta_set_sinfo(sta, sinfo);
 	}
 
-	rcu_read_unlock();
+	mutex_unlock(&local->sta_mtx);
 
 	return ret;
 }

net/mac80211/driver-ops.h

@@ -845,4 +845,19 @@ drv_allow_buffered_frames(struct ieee80211_local *local,
 						  more_data);
 	trace_drv_return_void(local);
 }
+
+static inline int drv_get_rssi(struct ieee80211_local *local,
+				struct ieee80211_sub_if_data *sdata,
+				struct ieee80211_sta *sta,
+				s8 *rssi_dbm)
+{
+	int ret;
+
+	might_sleep();
+
+	ret = local->ops->get_rssi(&local->hw, &sdata->vif, sta, rssi_dbm);
+	trace_drv_get_rssi(local, sta, *rssi_dbm, ret);
+
+	return ret;
+}
 #endif /* __MAC80211_DRIVER_OPS */

net/mac80211/driver-trace.h

@@ -1218,6 +1218,32 @@ DEFINE_EVENT(release_evt, drv_allow_buffered_frames,
 	TP_ARGS(local, sta, tids, num_frames, reason, more_data)
 );
 
+TRACE_EVENT(drv_get_rssi,
+	TP_PROTO(struct ieee80211_local *local, struct ieee80211_sta *sta,
+		 s8 rssi, int ret),
+
+	TP_ARGS(local, sta, rssi, ret),
+
+	TP_STRUCT__entry(
+		LOCAL_ENTRY
+		STA_ENTRY
+		__field(s8, rssi)
+		__field(int, ret)
+	),
+
+	TP_fast_assign(
+		LOCAL_ASSIGN;
+		STA_ASSIGN;
+		__entry->rssi = rssi;
+		__entry->ret = ret;
+	),
+
+	TP_printk(
+		LOCAL_PR_FMT STA_PR_FMT " rssi:%d ret:%d",
+		LOCAL_PR_ARG, STA_PR_ARG, __entry->rssi, __entry->ret
+	)
+);
+
 /*
  * Tracing for API calls that drivers call.
  */