ath9k: add back support for using active monitor interfaces for tx99

Various documented examples on how to set up tx99 with ath9k rely
on setting up a regular monitor interface for setting the channel.
My previous patch "ath9k: fix tx99 with monitor mode interface" made
it possible to set it up this way again. However, it was removing support
for using an active monitor interface, which is required for controlling
the bitrate as well, since the bitrate is not passed down with a regular
monitor interface.

This patch partially reverts the previous one, but keeps support for using
a regular monitor interface to keep documented steps working in cases
where the bitrate does not matter

Fixes: d9c52fd17cb48 ("ath9k: fix tx99 with monitor mode interface")
Signed-off-by: Felix Fietkau <nbd@nbd.name>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>

drivers/net/wireless/ath/ath9k/ath9k.h

@@ -1074,6 +1074,7 @@ struct ath_softc {
 
 	struct ath_spec_scan_priv spec_priv;
 
+	struct ieee80211_vif *tx99_vif;
 	struct sk_buff *tx99_skb;
 	bool tx99_state;
 	s16 tx99_power;

drivers/net/wireless/ath/ath9k/main.c

@@ -1251,8 +1251,13 @@ static int ath9k_add_interface(struct ieee80211_hw *hw,
 	struct ath_vif *avp = (void *)vif->drv_priv;
 	struct ath_node *an = &avp->mcast_node;
 
-	if (IS_ENABLED(CONFIG_ATH9K_TX99))
-		return -EOPNOTSUPP;
+	if (IS_ENABLED(CONFIG_ATH9K_TX99)) {
+		if (sc->cur_chan->nvifs >= 1) {
+			mutex_unlock(&sc->mutex);
+			return -EOPNOTSUPP;
+		}
+		sc->tx99_vif = vif;
+	}
 
 	mutex_lock(&sc->mutex);
 
@@ -1337,6 +1342,7 @@ static void ath9k_remove_interface(struct ieee80211_hw *hw,
 	ath9k_p2p_remove_vif(sc, vif);
 
 	sc->cur_chan->nvifs--;
+	sc->tx99_vif = NULL;
 	if (!ath9k_is_chanctx_enabled())
 		list_del(&avp->list);
 

drivers/net/wireless/ath/ath9k/tx99.c

@@ -54,6 +54,7 @@ static struct sk_buff *ath9k_build_tx99_skb(struct ath_softc *sc)
 	struct ieee80211_hdr *hdr;
 	struct ieee80211_tx_info *tx_info;
 	struct sk_buff *skb;
+	struct ath_vif *avp;
 
 	skb = alloc_skb(len, GFP_KERNEL);
 	if (!skb)
@@ -71,11 +72,17 @@ static struct sk_buff *ath9k_build_tx99_skb(struct ath_softc *sc)
 	memcpy(hdr->addr2, hw->wiphy->perm_addr, ETH_ALEN);
 	memcpy(hdr->addr3, hw->wiphy->perm_addr, ETH_ALEN);
 
+	if (sc->tx99_vif) {
+		avp = (struct ath_vif *) sc->tx99_vif->drv_priv;
+		hdr->seq_ctrl |= cpu_to_le16(avp->seq_no);
+	}
+
 	tx_info = IEEE80211_SKB_CB(skb);
 	memset(tx_info, 0, sizeof(*tx_info));
 	rate = &tx_info->control.rates[0];
 	tx_info->band = sc->cur_chan->chandef.chan->band;
 	tx_info->flags = IEEE80211_TX_CTL_NO_ACK;
+	tx_info->control.vif = sc->tx99_vif;
 	rate->count = 1;
 	if (ah->curchan && IS_CHAN_HT(ah->curchan)) {
 		rate->flags |= IEEE80211_TX_RC_MCS;

drivers/net/wireless/ath/ath9k/xmit.c

@@ -2973,7 +2973,7 @@ int ath9k_tx99_send(struct ath_softc *sc, struct sk_buff *skb,
 		return -EINVAL;
 	}
 
-	ath_set_rates(NULL, NULL, bf);
+	ath_set_rates(sc->tx99_vif, NULL, bf);
 
 	ath9k_hw_set_desc_link(sc->sc_ah, bf->bf_desc, bf->bf_daddr);
 	ath9k_hw_tx99_start(sc->sc_ah, txctl->txq->axq_qnum);