nl80211/mac80211: Report signal average

Extend nl80211 to report an exponential weighted moving average (EWMA) of the
signal value. Since the signal value usually fluctuates between different
packets, an average can be more useful than the value of the last packet.

This uses the recently added generic EWMA library function.

Signed-off-by: Bruno Randolf <br1@einfach.org>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

8 files changed, 18 insertions, 1 deletions

diff --git a/include/linux/nl80211.h b/include/linux/nl80211.h
index 037b4e498890..1ce3775e9e26 100644
--- a/include/linux/nl80211.h
+++ b/include/linux/nl80211.h
@@ -1161,6 +1161,7 @@ enum nl80211_rate_info {
  * @__NL80211_STA_INFO_AFTER_LAST: internal
  * @NL80211_STA_INFO_MAX: highest possible station info attribute
  * @NL80211_STA_INFO_SIGNAL: signal strength of last received PPDU (u8, dBm)
+ * @NL80211_STA_INFO_SIGNAL_AVG: signal strength average (u8, dBm)
  * @NL80211_STA_INFO_TX_BITRATE: current unicast tx rate, nested attribute
  *      containing info as possible, see &enum nl80211_sta_info_txrate.
  * @NL80211_STA_INFO_RX_PACKETS: total received packet (u32, from this station)
@@ -1178,6 +1179,7 @@ enum nl80211_sta_info {
         NL80211_STA_INFO_PLID,
         NL80211_STA_INFO_PLINK_STATE,
         NL80211_STA_INFO_SIGNAL,
+        NL80211_STA_INFO_SIGNAL_AVG,
         NL80211_STA_INFO_TX_BITRATE,
         NL80211_STA_INFO_RX_PACKETS,
         NL80211_STA_INFO_TX_PACKETS,
diff --git a/include/net/cfg80211.h b/include/net/cfg80211.h
index 8fd9eebd0cc9..69e2364889f1 100644
--- a/include/net/cfg80211.h
+++ b/include/net/cfg80211.h
@@ -424,6 +424,7 @@ struct station_parameters {
  * @STATION_INFO_TX_RETRIES: @tx_retries filled
  * @STATION_INFO_TX_FAILED: @tx_failed filled
  * @STATION_INFO_RX_DROP_MISC: @rx_dropped_misc filled
+ * @STATION_INFO_SIGNAL_AVG: @signal_avg filled
  */
 enum station_info_flags {
         STATION_INFO_INACTIVE_TIME      = 1<<0,
@@ -439,6 +440,7 @@ enum station_info_flags {
         STATION_INFO_TX_RETRIES         = 1<<10,
         STATION_INFO_TX_FAILED          = 1<<11,
         STATION_INFO_RX_DROP_MISC       = 1<<12,
+        STATION_INFO_SIGNAL_AVG         = 1<<13,
 };
 
 /**
@@ -485,6 +487,7 @@ struct rate_info {
  * @plid: mesh peer link id
  * @plink_state: mesh peer link state
  * @signal: signal strength of last received packet in dBm
+ * @signal_avg: signal strength average in dBm
  * @txrate: current unicast bitrate to this station
  * @rx_packets: packets received from this station
  * @tx_packets: packets transmitted to this station
@@ -505,6 +508,7 @@ struct station_info {
         u16 plid;
         u8 plink_state;
         s8 signal;
+        s8 signal_avg;
         struct rate_info txrate;
         u32 rx_packets;
         u32 tx_packets;
diff --git a/net/mac80211/Kconfig b/net/mac80211/Kconfig
index 4d6f8653ec88..798d9b9462e2 100644
--- a/net/mac80211/Kconfig
+++ b/net/mac80211/Kconfig
@@ -6,6 +6,7 @@ config MAC80211
         select CRYPTO_ARC4
         select CRYPTO_AES
         select CRC32
+        select AVERAGE
         ---help---
           This option enables the hardware independent IEEE 802.11
           networking stack.
diff --git a/net/mac80211/cfg.c b/net/mac80211/cfg.c
index 0c544074479e..92c9cf6a7d1c 100644
--- a/net/mac80211/cfg.c
+++ b/net/mac80211/cfg.c
@@ -343,8 +343,9 @@ 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;
+                sinfo->filled |= STATION_INFO_SIGNAL | STATION_INFO_SIGNAL_AVG;
                 sinfo->signal = (s8)sta->last_signal;
+                sinfo->signal_avg = (s8) -ewma_read(&sta->avg_signal);
         }
 
         sinfo->txrate.flags = 0;
diff --git a/net/mac80211/rx.c b/net/mac80211/rx.c
index d2fcd22ab06d..9dd60a74181f 100644
--- a/net/mac80211/rx.c
+++ b/net/mac80211/rx.c
@@ -1156,6 +1156,7 @@ ieee80211_rx_h_sta_process(struct ieee80211_rx_data *rx)
         sta->rx_fragments++;
         sta->rx_bytes += rx->skb->len;
         sta->last_signal = status->signal;
+        ewma_add(&sta->avg_signal, -status->signal);
 
         /*
          * Change STA power saving mode only at the end of a frame
diff --git a/net/mac80211/sta_info.c b/net/mac80211/sta_info.c
index eff58571fd7e..f43fca8907f7 100644
--- a/net/mac80211/sta_info.c
+++ b/net/mac80211/sta_info.c
@@ -244,6 +244,8 @@ struct sta_info *sta_info_alloc(struct ieee80211_sub_if_data *sdata,
         sta->local = local;
         sta->sdata = sdata;
 
+        ewma_init(&sta->avg_signal, 1000, 8);
+
         if (sta_prepare_rate_control(local, sta, gfp)) {
                 kfree(sta);
                 return NULL;
diff --git a/net/mac80211/sta_info.h b/net/mac80211/sta_info.h
index 9265acadef32..84062e2c782c 100644
--- a/net/mac80211/sta_info.h
+++ b/net/mac80211/sta_info.h
@@ -13,6 +13,7 @@
 #include <linux/types.h>
 #include <linux/if_ether.h>
 #include <linux/workqueue.h>
+#include <linux/average.h>
 #include "key.h"
 
 /**
@@ -224,6 +225,7 @@ enum plink_state {
  * @rx_fragments: number of received MPDUs
  * @rx_dropped: number of dropped MPDUs from this STA
  * @last_signal: signal of last received frame from this STA
+ * @avg_signal: moving average of signal of received frames from this STA
  * @last_seq_ctrl: last received seq/frag number from this STA (per RX queue)
  * @tx_filtered_count: number of frames the hardware filtered for this STA
  * @tx_retry_failed: number of frames that failed retry
@@ -291,6 +293,7 @@ struct sta_info {
         unsigned long rx_fragments;
         unsigned long rx_dropped;
         int last_signal;
+        struct ewma avg_signal;
         __le16 last_seq_ctrl[NUM_RX_DATA_QUEUES];
 
         /* Updated from TX status path only, no locking requirements */
diff --git a/net/wireless/nl80211.c b/net/wireless/nl80211.c
index 605553842226..d06a40d17002 100644
--- a/net/wireless/nl80211.c
+++ b/net/wireless/nl80211.c
@@ -1872,6 +1872,9 @@ static int nl80211_send_station(struct sk_buff *msg, u32 pid, u32 seq,
         if (sinfo->filled & STATION_INFO_SIGNAL)
                 NLA_PUT_U8(msg, NL80211_STA_INFO_SIGNAL,
                            sinfo->signal);
+        if (sinfo->filled & STATION_INFO_SIGNAL_AVG)
+                NLA_PUT_U8(msg, NL80211_STA_INFO_SIGNAL_AVG,
+                           sinfo->signal_avg);
         if (sinfo->filled & STATION_INFO_TX_BITRATE) {
                 txrate = nla_nest_start(msg, NL80211_STA_INFO_TX_BITRATE);
                 if (!txrate)