cfg80211: add local BSS receive time to survey information

This is useful for checking how much airtime is being used up by other
transmissions on the channel, e.g. by calculating (time_rx - time_bss_rx)
or (time_busy - time_bss_rx - time_tx)

Signed-off-by: Felix Fietkau <nbd@nbd.name>
Link: https://lore.kernel.org/r/20190828102042.58016-1-nbd@nbd.name
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

include/net/cfg80211.h

@@ -768,6 +768,7 @@ ieee80211_chandef_max_power(struct cfg80211_chan_def *chandef)
  * @SURVEY_INFO_TIME_RX: receive time was filled in
  * @SURVEY_INFO_TIME_TX: transmit time was filled in
  * @SURVEY_INFO_TIME_SCAN: scan time was filled in
+ * @SURVEY_INFO_TIME_BSS_RX: local BSS receive time was filled in
  *
  * Used by the driver to indicate which info in &struct survey_info
  * it has filled in during the get_survey().
@@ -781,6 +782,7 @@ enum survey_info_flags {
 	SURVEY_INFO_TIME_RX		= BIT(5),
 	SURVEY_INFO_TIME_TX		= BIT(6),
 	SURVEY_INFO_TIME_SCAN		= BIT(7),
+	SURVEY_INFO_TIME_BSS_RX		= BIT(8),
 };
 
 /**
@@ -797,6 +799,7 @@ enum survey_info_flags {
  * @time_rx: amount of time the radio spent receiving data
  * @time_tx: amount of time the radio spent transmitting data
  * @time_scan: amount of time the radio spent for scanning
+ * @time_bss_rx: amount of time the radio spent receiving data on a local BSS
  *
  * Used by dump_survey() to report back per-channel survey information.
  *
@@ -811,6 +814,7 @@ struct survey_info {
 	u64 time_rx;
 	u64 time_tx;
 	u64 time_scan;
+	u64 time_bss_rx;
 	u32 filled;
 	s8 noise;
 };

include/uapi/linux/nl80211.h

@@ -3870,6 +3870,8 @@ enum nl80211_user_reg_hint_type {
  * @NL80211_SURVEY_INFO_TIME_SCAN: time the radio spent for scan
  *	(on this channel or globally)
  * @NL80211_SURVEY_INFO_PAD: attribute used for padding for 64-bit alignment
+ * @NL80211_SURVEY_INFO_TIME_BSS_RX: amount of time the radio spent
+ *	receiving frames destined to the local BSS
  * @NL80211_SURVEY_INFO_MAX: highest survey info attribute number
  *	currently defined
  * @__NL80211_SURVEY_INFO_AFTER_LAST: internal use
@@ -3886,6 +3888,7 @@ enum nl80211_survey_info {
 	NL80211_SURVEY_INFO_TIME_TX,
 	NL80211_SURVEY_INFO_TIME_SCAN,
 	NL80211_SURVEY_INFO_PAD,
+	NL80211_SURVEY_INFO_TIME_BSS_RX,
 
 	/* keep last */
 	__NL80211_SURVEY_INFO_AFTER_LAST,

net/wireless/nl80211.c

@@ -8806,6 +8806,10 @@ static int nl80211_send_survey(struct sk_buff *msg, u32 portid, u32 seq,
 	    nla_put_u64_64bit(msg, NL80211_SURVEY_INFO_TIME_SCAN,
 			      survey->time_scan, NL80211_SURVEY_INFO_PAD))
 		goto nla_put_failure;
+	if ((survey->filled & SURVEY_INFO_TIME_BSS_RX) &&
+	    nla_put_u64_64bit(msg, NL80211_SURVEY_INFO_TIME_BSS_RX,
+			      survey->time_bss_rx, NL80211_SURVEY_INFO_PAD))
+		goto nla_put_failure;
 
 	nla_nest_end(msg, infoattr);