mac80211: add time synchronisation with BSS for assoc

Some drivers (iwlegacy, iwlwifi and rt2x00) today use the
bss_conf.last_tsf value. By itself though that value is
completely worthless since it may be ancient. What really
is needed is synchronisation between some device time and
the TSF.

To clarify this, rename bss_conf.last_tsf to sync_tsf and
add sync_device_ts which is obtained from rx_status which
gets a new field device_timestamp for this purpose. This
is intentionally not using the mactime field since that
is used for other things and in IBSS is expected to sync
with the IBSS's TSF which isn't necessarily true for the
device timestamp.

Also, since we have the information and it's useful even
before the connection has been established, give all the
timing details to the driver before authenticating.

Reviewed-by: Emmanuel Grumbach <emmanuel.grumbach@intel.com>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

4 files changed, 16 insertions, 10 deletions

diff --git a/net/mac80211/ieee80211_i.h b/net/mac80211/ieee80211_i.h
index 2a97d66..7998513 100644
--- a/net/mac80211/ieee80211_i.h
+++ b/net/mac80211/ieee80211_i.h
@@ -85,6 +85,8 @@ struct ieee80211_bss {
 	size_t ssid_len;
 	u8 ssid[IEEE80211_MAX_SSID_LEN];
 
+	u32 device_ts;
+
 	u8 dtim_period;
 
 	bool wmm_used;
diff --git a/net/mac80211/mlme.c b/net/mac80211/mlme.c
index 4b503ce..4efcbf8 100644
--- a/net/mac80211/mlme.c
+++ b/net/mac80211/mlme.c
@@ -1269,11 +1269,6 @@ static void ieee80211_set_associated(struct ieee80211_sub_if_data *sdata,
 	struct ieee80211_bss_conf *bss_conf = &sdata->vif.bss_conf;
 
 	bss_info_changed |= BSS_CHANGED_ASSOC;
-	/* set timing information */
-	bss_conf->beacon_int = cbss->beacon_interval;
-	bss_conf->last_tsf = cbss->tsf;
-
-	bss_info_changed |= BSS_CHANGED_BEACON_INT;
 	bss_info_changed |= ieee80211_handle_bss_capability(sdata,
 		bss_conf->assoc_capability, bss->has_erp_value, bss->erp_value);
 
@@ -3135,9 +3130,15 @@ static int ieee80211_prep_connection(struct ieee80211_sub_if_data *sdata,
 
 		memcpy(ifmgd->bssid, cbss->bssid, ETH_ALEN);
 
-		/* tell driver about BSSID and basic rates */
+		/* set timing information */
+		sdata->vif.bss_conf.beacon_int = cbss->beacon_interval;
+		sdata->vif.bss_conf.sync_tsf = cbss->tsf;
+		sdata->vif.bss_conf.sync_device_ts = bss->device_ts;
+
+		/* tell driver about BSSID, basic rates and timing */
 		ieee80211_bss_info_change_notify(sdata,
-			BSS_CHANGED_BSSID | BSS_CHANGED_BASIC_RATES);
+			BSS_CHANGED_BSSID | BSS_CHANGED_BASIC_RATES |
+			BSS_CHANGED_BEACON_INT);
 
 		if (assoc)
 			sta_info_pre_move_state(sta, IEEE80211_STA_AUTH);
diff --git a/net/mac80211/scan.c b/net/mac80211/scan.c
index 1a893f3..e80a8b6 100644
--- a/net/mac80211/scan.c
+++ b/net/mac80211/scan.c
@@ -83,13 +83,14 @@ ieee80211_bss_info_update(struct ieee80211_local *local,
 
 	cbss = cfg80211_inform_bss_frame(local->hw.wiphy, channel,
 					 mgmt, len, signal, GFP_ATOMIC);
-
 	if (!cbss)
 		return NULL;
 
 	cbss->free_priv = ieee80211_rx_bss_free;
 	bss = (void *)cbss->priv;
 
+	bss->device_ts = rx_status->device_timestamp;
+
 	if (elems->parse_error) {
 		if (beacon)
 			bss->corrupt_data |= IEEE80211_BSS_CORRUPT_BEACON;
diff --git a/net/mac80211/trace.h b/net/mac80211/trace.h
index e1e9d10..c6d33b5 100644
--- a/net/mac80211/trace.h
+++ b/net/mac80211/trace.h
@@ -306,7 +306,8 @@ TRACE_EVENT(drv_bss_info_changed,
 		__field(u8, dtimper)
 		__field(u16, bcnint)
 		__field(u16, assoc_cap)
-		__field(u64, timestamp)
+		__field(u64, sync_tsf)
+		__field(u32, sync_device_ts)
 		__field(u32, basic_rates)
 		__field(u32, changed)
 		__field(bool, enable_beacon)
@@ -325,7 +326,8 @@ TRACE_EVENT(drv_bss_info_changed,
 		__entry->dtimper = info->dtim_period;
 		__entry->bcnint = info->beacon_int;
 		__entry->assoc_cap = info->assoc_capability;
-		__entry->timestamp = info->last_tsf;
+		__entry->sync_tsf = info->sync_tsf;
+		__entry->sync_device_ts = info->sync_device_ts;
 		__entry->basic_rates = info->basic_rates;
 		__entry->enable_beacon = info->enable_beacon;
 		__entry->ht_operation_mode = info->ht_operation_mode;