[PATCH v7 3/3] nl80211/mac80211: Report signal average

[Bruno Randolf <br1@einfach.org>]

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>
---
 include/linux/nl80211.h |    2 ++
 include/net/cfg80211.h  |    4 ++++
 net/mac80211/Kconfig    |    1 +
 net/mac80211/cfg.c      |    3 ++-
 net/mac80211/rx.c       |    1 +
 net/mac80211/sta_info.c |    2 ++
 net/mac80211/sta_info.h |    3 +++
 net/wireless/nl80211.c  |    3 +++
 8 files changed, 18 insertions(+), 1 deletions(-)

diff --git a/include/linux/nl80211.h b/include/linux/nl80211.h
index fb877b5..0ceb552 100644
--- a/include/linux/nl80211.h
+++ b/include/linux/nl80211.h
@@ -1132,6 +1132,7 @@ 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)
@@ -1149,6 +1150,7 @@ 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 e5702f5..f21f701 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 4d6f865..798d9b9 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 18bd0e5..d327918 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_get(&sta->avg_signal);
 	}
 
 	sinfo->txrate.flags = 0;
diff --git a/net/mac80211/rx.c b/net/mac80211/rx.c
index 902b03e..34bcc84 100644
--- a/net/mac80211/rx.c
+++ b/net/mac80211/rx.c
@@ -1158,6 +1158,7 @@ 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 6d8f897..bed23e1 100644
--- a/net/mac80211/sta_info.c
+++ b/net/mac80211/sta_info.c
@@ -241,6 +241,8 @@ 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 9265aca..84062e2 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 4e78e3f..660987d 100644
--- a/net/wireless/nl80211.c
+++ b/net/wireless/nl80211.c
@@ -1841,6 +1841,9 @@ 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)