ath9k: Adjust AP beacon tsf based on station context

In multi channel context (AP + STA case), adjust the TSF time of
the AP chanctx to keep its beacons at half beacon interval offset
relative to the STA chanctx.

Signed-off-by: Felix Fietkau <nbd@openwrt.org>
Signed-off-by: Rajkumar Manoharan <rmanohar@qti.qualcomm.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

3 files changed, 55 insertions, 0 deletions

diff --git a/drivers/net/wireless/ath/ath9k/ath9k.h b/drivers/net/wireless/ath/ath9k/ath9k.h
index 02f30980c31a..a4646a076099 100644
--- a/drivers/net/wireless/ath/ath9k/ath9k.h
+++ b/drivers/net/wireless/ath/ath9k/ath9k.h
@@ -335,6 +335,7 @@ struct ath_chanctx {
         struct ath9k_hw_cal_data caldata;
         struct timespec tsf_ts;
         u64 tsf_val;
+        u32 last_beacon;
 
         u16 txpower;
         bool offchannel;
@@ -348,6 +349,7 @@ enum ath_chanctx_event {
         ATH_CHANCTX_EVENT_BEACON_PREPARE,
         ATH_CHANCTX_EVENT_BEACON_SENT,
         ATH_CHANCTX_EVENT_TSF_TIMER,
+        ATH_CHANCTX_EVENT_BEACON_RECEIVED,
 };
 
 enum ath_chanctx_state {
diff --git a/drivers/net/wireless/ath/ath9k/channel.c b/drivers/net/wireless/ath/ath9k/channel.c
index 4793de079f77..6ea806cc68fe 100644
--- a/drivers/net/wireless/ath/ath9k/channel.c
+++ b/drivers/net/wireless/ath/ath9k/channel.c
@@ -382,10 +382,51 @@ void ath_chanctx_offchan_switch(struct ath_softc *sc,
         ath_chanctx_switch(sc, &sc->offchannel.chan, &chandef);
 }
 
+static struct ath_chanctx *
+ath_chanctx_get_next(struct ath_softc *sc, struct ath_chanctx *ctx)
+{
+        int idx = ctx - &sc->chanctx[0];
+
+        return &sc->chanctx[!idx];
+}
+
+static void ath_chanctx_adjust_tbtt_delta(struct ath_softc *sc)
+{
+        struct ath_chanctx *prev, *cur;
+        struct timespec ts;
+        u32 cur_tsf, prev_tsf, beacon_int;
+        s32 offset;
+
+        beacon_int = TU_TO_USEC(sc->cur_chan->beacon.beacon_interval);
+
+        cur = sc->cur_chan;
+        prev = ath_chanctx_get_next(sc, cur);
+
+        getrawmonotonic(&ts);
+        cur_tsf = (u32) cur->tsf_val +
+                  ath9k_hw_get_tsf_offset(&cur->tsf_ts, &ts);
+
+        prev_tsf = prev->last_beacon - (u32) prev->tsf_val + cur_tsf;
+        prev_tsf -= ath9k_hw_get_tsf_offset(&prev->tsf_ts, &ts);
+
+        /* Adjust the TSF time of the AP chanctx to keep its beacons
+         * at half beacon interval offset relative to the STA chanctx.
+         */
+        offset = cur_tsf - prev_tsf;
+
+        /* Ignore stale data or spurious timestamps */
+        if (offset < 0 || offset > 3 * beacon_int)
+                return;
+
+        offset = beacon_int / 2 - (offset % beacon_int);
+        prev->tsf_val += offset;
+}
+
 void ath_chanctx_event(struct ath_softc *sc, struct ieee80211_vif *vif,
                        enum ath_chanctx_event ev)
 {
         struct ath_hw *ah = sc->sc_ah;
+        struct ath_common *common = ath9k_hw_common(ah);
         struct ath_vif *avp = NULL;
         u32 tsf_time;
         bool noa_changed = false;
@@ -410,6 +451,7 @@ void ath_chanctx_event(struct ath_softc *sc, struct ieee80211_vif *vif,
                 tsf_time = TU_TO_USEC(sc->cur_chan->beacon.beacon_interval);
                 tsf_time = sc->sched.next_tbtt + tsf_time / 4;
                 sc->sched.switch_start_time = tsf_time;
+                sc->cur_chan->last_beacon = sc->sched.next_tbtt;
 
                 if (sc->sched.offchannel_duration) {
                         noa_changed = true;
@@ -441,6 +483,12 @@ void ath_chanctx_event(struct ath_softc *sc, struct ieee80211_vif *vif,
                 sc->sched.state = ATH_CHANCTX_STATE_SWITCH;
                 ieee80211_queue_work(sc->hw, &sc->chanctx_work);
                 break;
+        case ATH_CHANCTX_EVENT_BEACON_RECEIVED:
+                if (!test_bit(ATH_OP_MULTI_CHANNEL, &common->op_flags))
+                        break;
+
+                ath_chanctx_adjust_tbtt_delta(sc);
+                break;
         }
 
         spin_unlock_bh(&sc->chan_lock);
diff --git a/drivers/net/wireless/ath/ath9k/recv.c b/drivers/net/wireless/ath/ath9k/recv.c
index 7b9c7e53caaa..74ab1d02013b 100644
--- a/drivers/net/wireless/ath/ath9k/recv.c
+++ b/drivers/net/wireless/ath/ath9k/recv.c
@@ -892,6 +892,11 @@ static int ath9k_rx_skb_preprocess(struct ath_softc *sc,
                 return -EINVAL;
         }
 
+        if (rx_stats->is_mybeacon) {
+                sc->sched.next_tbtt = rx_stats->rs_tstamp;
+                ath_chanctx_event(sc, NULL, ATH_CHANCTX_EVENT_BEACON_RECEIVED);
+        }
+
         ath9k_cmn_process_rssi(common, hw, rx_stats, rx_status);
 
         rx_status->band = ah->curchan->chan->band;