[PATCH wireless-next v3 14/21] wifi: mac80211: add driver_op for SMD substate changes

[Pooventhiran G <pooventhiran.g@oss.qualcomm.com>]

During SMD BSS Transition, a non-AP MLD moves through sub-states 4a,
4b, and 4c that impose different frame-filtering rules on the AP MLD.

Add a new driver op that mac80211 calls on each sub-state transition.
This lets drivers perform the necessary hardware queue and filtering
adjustments at each phase of the SMD BSS Transition.

Valid transition order:
  NONE  -> PREP  (ST preparation completed at the target AP MLD)
  NONE  -> EXEC  (ST execution in progress at the current AP MLD)
  EXEC  -> DRAIN (DL drain period started at the current AP MLD)

Suggested-by: Rohan Dutta <drohan@qti.qualcomm.com>
Signed-off-by: Pooventhiran G <pooventhiran.g@oss.qualcomm.com>
---
 include/net/mac80211.h    |  26 +++++++++
 net/mac80211/cfg.c        |  59 ++++++++++++++-----
 net/mac80211/driver-ops.c |  24 ++++++++
 net/mac80211/driver-ops.h |   6 ++
 net/mac80211/sta_info.c   | 140 ++++++++++++++++++++++++++++++++++++++++++++++
 net/mac80211/sta_info.h   |   9 +++
 net/mac80211/trace.h      |  33 +++++++++++
 7 files changed, 284 insertions(+), 13 deletions(-)

diff --git a/include/net/mac80211.h b/include/net/mac80211.h
index 23a3f08c72e3..96acdb9ae8f0 100644
--- a/include/net/mac80211.h
+++ b/include/net/mac80211.h
@@ -4092,6 +4092,24 @@ struct ieee80211_prep_tx_info {
 	int link_id;
 };
 
+/**
+ * enum ieee80211_sta_smd_state - SMD BSS Transition sub-state
+ *
+ * Tracks the 802.11bn SMD BSS Transition sub-state (IEEE P802.11bn/D2.0,
+ * Aug 2026, subclause 11.3.1) for a specific (non-AP MLD, AP MLD) association.
+ *
+ * @IEEE80211_STA_SMD_NONE:  Plain State 4. No sub-state active.
+ * @IEEE80211_STA_SMD_PREP:  State 4a. STA prepared at the target AP MLD
+ * @IEEE80211_STA_SMD_EXEC:  State 4b. ST execution active at the current AP MLD
+ * @IEEE80211_STA_SMD_DRAIN: State 4c. DL draining period at the current AP MLD
+ */
+enum ieee80211_sta_smd_state {
+	IEEE80211_STA_SMD_NONE,
+	IEEE80211_STA_SMD_PREP,
+	IEEE80211_STA_SMD_EXEC,
+	IEEE80211_STA_SMD_DRAIN,
+};
+
 /**
  * struct ieee80211_ops - callbacks from mac80211 to the driver
  *
@@ -4771,6 +4789,9 @@ struct ieee80211_prep_tx_info {
  * @set_eml_op_mode: Configure eMLSR/eMLMR operation mode in the underlay
  *	driver according to the parameter received in the EML Operating mode
  *	notification frame.
+ * @sta_smd_state: Notifies low level driver about IEEE 802.11bn SMD substate
+ *	transition of a station. It must not fail while transitioning down.
+ *	The callback can sleep.
  */
 struct ieee80211_ops {
 	void (*tx)(struct ieee80211_hw *hw,
@@ -5184,6 +5205,11 @@ struct ieee80211_ops {
 			       struct ieee80211_vif *vif,
 			       struct ieee80211_sta *sta,
 			       struct ieee80211_eml_params *eml_params);
+	int (*sta_smd_state)(struct ieee80211_hw *hw,
+			     struct ieee80211_vif *vif,
+			     struct ieee80211_sta *sta,
+			     enum ieee80211_sta_smd_state old_state,
+			     enum ieee80211_sta_smd_state new_state);
 };
 
 /**
diff --git a/net/mac80211/cfg.c b/net/mac80211/cfg.c
index 1e0ef74a7420..af9fe323c11b 100644
--- a/net/mac80211/cfg.c
+++ b/net/mac80211/cfg.c
@@ -2711,7 +2711,9 @@ static int sta_apply_smd_state_flags(struct sta_info *sta,
 	u32 expected_mask = BIT(NL80211_STA_FLAG_SMD_PREP_TARGET) |
 			    BIT(NL80211_STA_FLAG_SMD_EXEC_CURRENT) |
 			    BIT(NL80211_STA_FLAG_SMD_DL_DRAIN);
+	enum ieee80211_sta_smd_state new_ss;
 	u32 smd_flags;
+	int err;
 
 	if (!(mask & expected_mask))
 		return 0;
@@ -2731,6 +2733,22 @@ static int sta_apply_smd_state_flags(struct sta_info *sta,
 	    (smd_exec_current || smd_dl_drain))
 		return -EINVAL;
 
+	if (smd_prep_target)
+		new_ss = IEEE80211_STA_SMD_PREP;
+	else if (smd_exec_current)
+		new_ss = IEEE80211_STA_SMD_EXEC;
+	else if (smd_dl_drain)
+		new_ss = IEEE80211_STA_SMD_DRAIN;
+	else
+		new_ss = IEEE80211_STA_SMD_NONE;
+
+	if (new_ss == sta->smd_state)
+		return 0;
+
+	err = sta_info_move_smd_state(sta, new_ss, true);
+	if (err)
+		return err;
+
 	if (smd_prep_target) {
 		clear_sta_flag(sta, WLAN_STA_SMD_EXEC_CURRENT);
 		clear_sta_flag(sta, WLAN_STA_SMD_DL_DRAIN);
@@ -2830,26 +2848,17 @@ static int sta_apply_parameters(struct ieee80211_local *local,
 		sta->sta.spp_amsdu = set & BIT(NL80211_STA_FLAG_SPP_AMSDU);
 
 	if (mask & BIT(NL80211_STA_FLAG_SMD)) {
-		if (set & BIT(NL80211_STA_FLAG_SMD))
+		if (set & BIT(NL80211_STA_FLAG_SMD)) {
 			set_sta_flag(sta, WLAN_STA_SMD);
-		else if (test_sta_flag(sta, WLAN_STA_SMD))
+		} else if (test_sta_flag(sta, WLAN_STA_SMD)) {
+			sta_info_reset_smd_state(sta, true);
 			clear_sta_flag(sta, WLAN_STA_SMD);
+		}
 	}
 
 	if (params->smd_params.smd_sta)
 		sta->sta.smd_params = params->smd_params;
 
-	/*
-	 * SMD BSS Transition sub-states (IEEE P802.11bn/D2.0, Aug 2026,
-	 * subclause 11.3.1).
-	 * Only meaningful for SMD-capable stations (WLAN_STA_SMD set).
-	 */
-	if (test_sta_flag(sta, WLAN_STA_SMD)) {
-		ret = sta_apply_smd_state_flags(sta, mask, set);
-		if (ret)
-			return ret;
-	}
-
 	/* mark TDLS channel switch support, if the AP allows it */
 	if (test_sta_flag(sta, WLAN_STA_TDLS_PEER) &&
 	    !sdata->deflink.u.mgd.tdls_chan_switch_prohibited &&
@@ -2954,6 +2963,17 @@ static int sta_apply_parameters(struct ieee80211_local *local,
 			return ret;
 	}
 
+	/*
+	 * SMD BSS Transition sub-states (IEEE P802.11bn/D2.0, Aug 2026,
+	 * subclause 11.3.1).
+	 * Only meaningful for SMD-capable stations (WLAN_STA_SMD set).
+	 */
+	if (test_sta_flag(sta, WLAN_STA_SMD)) {
+		ret = sta_apply_smd_state_flags(sta, mask, set);
+		if (ret)
+			return ret;
+	}
+
 	/* Mark the STA as MLO if MLD MAC address is available */
 	if (params->link_sta_params.mld_mac)
 		sta->sta.mlo = true;
@@ -3038,6 +3058,19 @@ static int ieee80211_add_station(struct wiphy *wiphy, struct wireless_dev *wdev,
 	 */
 	if (!err && sdata->vif.type == NL80211_IFTYPE_NAN_DATA)
 		ieee80211_nan_update_ndi_carrier(sta->sdata);
+
+	/*
+	 * SMD sub-state was set in sta_apply_parameters() before the station
+	 * was inserted so drv_sta_smd_state() was skipped (WLAN_STA_INSERTED
+	 * was not yet set). Walk the driver step-by-step to the target state.
+	 */
+	if (!err && test_sta_flag(sta, WLAN_STA_SMD) &&
+	    sta->smd_state != IEEE80211_STA_SMD_NONE) {
+		err = sta_info_move_drv_smd_state(sta);
+		if (err)
+			WARN_ON(__sta_info_destroy(sta));
+	}
+
 	return err;
 }
 
diff --git a/net/mac80211/driver-ops.c b/net/mac80211/driver-ops.c
index 1f3e0765a8ab..710efbfeeb31 100644
--- a/net/mac80211/driver-ops.c
+++ b/net/mac80211/driver-ops.c
@@ -709,3 +709,27 @@ int drv_link_sta_statistics(struct ieee80211_local *local,
 
 	return 0;
 }
+
+int drv_sta_smd_state(struct ieee80211_local *local,
+		      struct ieee80211_sub_if_data *sdata,
+		      struct ieee80211_sta *sta,
+		      enum ieee80211_sta_smd_state old_state,
+		      enum ieee80211_sta_smd_state new_state)
+{
+	int ret = 0;
+
+	might_sleep();
+	lockdep_assert_wiphy(local->hw.wiphy);
+
+	sdata = get_bss_sdata(sdata);
+	if (!check_sdata_in_driver(sdata))
+		return -EIO;
+
+	trace_drv_sta_smd_state(local, sdata, sta, old_state, new_state);
+	if (local->ops->sta_smd_state)
+		ret = local->ops->sta_smd_state(&local->hw, &sdata->vif,
+						sta, old_state, new_state);
+	trace_drv_return_int(local, ret);
+
+	return ret;
+}
diff --git a/net/mac80211/driver-ops.h b/net/mac80211/driver-ops.h
index 78230779e7fb..0cdd1f1c5315 100644
--- a/net/mac80211/driver-ops.h
+++ b/net/mac80211/driver-ops.h
@@ -1805,4 +1805,10 @@ drv_nan_peer_sched_changed(struct ieee80211_local *local,
 	return ret;
 }
 
+int drv_sta_smd_state(struct ieee80211_local *local,
+		      struct ieee80211_sub_if_data *sdata,
+		      struct ieee80211_sta *sta,
+		      enum ieee80211_sta_smd_state old_state,
+		      enum ieee80211_sta_smd_state new_state);
+
 #endif /* __MAC80211_DRIVER_OPS */
diff --git a/net/mac80211/sta_info.c b/net/mac80211/sta_info.c
index 23166fc39729..d4d1008887c9 100644
--- a/net/mac80211/sta_info.c
+++ b/net/mac80211/sta_info.c
@@ -701,6 +701,7 @@ __sta_info_alloc(struct ieee80211_sub_if_data *sdata,
 	ieee80211_init_frag_cache(&sta->frags);
 
 	sta->sta_state = IEEE80211_STA_NONE;
+	sta->smd_state = IEEE80211_STA_SMD_NONE;
 
 	if (sdata->vif.type == NL80211_IFTYPE_MESH_POINT)
 		sta->amsdu_mesh_control = -1;
@@ -1527,6 +1528,20 @@ static int _sta_info_move_state(struct sta_info *sta,
 		WARN_ONCE(err,
 			  "Driver is not allowed to fail if the sta_state is transitioning down the list: %d\n",
 			  err);
+
+		/* revert SMD states if STA has transitioned down */
+		if (new_state == IEEE80211_STA_AUTH &&
+		    sta->sta_state == IEEE80211_STA_ASSOC) {
+			if (test_sta_flag(sta, WLAN_STA_SMD) &&
+			    sta->smd_state == IEEE80211_STA_SMD_PREP)
+				sta_info_reset_smd_state(sta, true);
+		} else if (new_state == IEEE80211_STA_ASSOC &&
+			   sta->sta_state == IEEE80211_STA_AUTHORIZED) {
+			if (test_sta_flag(sta, WLAN_STA_SMD) &&
+			    sta->smd_state != IEEE80211_STA_SMD_NONE &&
+			    sta->smd_state != IEEE80211_STA_SMD_PREP)
+				sta_info_reset_smd_state(sta, true);
+		}
 	}
 
 	sta->sta_state = new_state;
@@ -3910,3 +3925,128 @@ bool ieee80211_link_sta_update_rc_bw(struct ieee80211_link_data *link,
 
 	return true;
 }
+
+int sta_info_move_smd_state(struct sta_info *sta,
+			    enum ieee80211_sta_smd_state new_ss,
+			    bool notify)
+{
+	enum ieee80211_sta_smd_state old_ss = sta->smd_state;
+	struct ieee80211_local *local = sta->local;
+	bool notify_driver;
+	int err;
+
+	might_sleep();
+
+	if (old_ss == new_ss)
+		return 0;
+
+	switch (new_ss) {
+	case IEEE80211_STA_SMD_NONE:
+		if (old_ss != IEEE80211_STA_SMD_PREP &&
+		    old_ss != IEEE80211_STA_SMD_EXEC &&
+		    old_ss != IEEE80211_STA_SMD_DRAIN)
+			return -EINVAL;
+		break;
+	case IEEE80211_STA_SMD_EXEC:
+		if (old_ss != IEEE80211_STA_SMD_NONE)
+			return -EINVAL;
+		break;
+	case IEEE80211_STA_SMD_DRAIN:
+		if (old_ss != IEEE80211_STA_SMD_EXEC)
+			return -EINVAL;
+		break;
+	case IEEE80211_STA_SMD_PREP:
+		if (old_ss != IEEE80211_STA_SMD_NONE)
+			return -EINVAL;
+		break;
+	default:
+		sdata_err(sta->sdata, "invalid smd state %d", new_ss);
+		return -EINVAL;
+	}
+
+	sta_dbg(sta->sdata, "moving STA %pM SMD state %u -> %u\n",
+		sta->sta.addr, old_ss, new_ss);
+
+	notify_driver = notify && test_sta_flag(sta, WLAN_STA_INSERTED);
+
+	if (new_ss > old_ss && notify_driver) {
+		err = drv_sta_smd_state(local, sta->sdata, &sta->sta, old_ss,
+					new_ss);
+		if (err)
+			return err;
+	}
+
+	if (new_ss < old_ss && notify_driver) {
+		err = drv_sta_smd_state(local, sta->sdata, &sta->sta, old_ss,
+					new_ss);
+		/* driver should not fail moving down SMD states */
+		WARN_ONCE(err,
+			  "Driver should not fail moving down SMD states: %d\n",
+			  err);
+	}
+
+	sta->smd_state = new_ss;
+
+	return 0;
+}
+
+void sta_info_reset_smd_state(struct sta_info *sta, bool notify)
+{
+	if (sta->smd_state == IEEE80211_STA_SMD_NONE)
+		return;
+
+	/* DRAIN -> NONE, EXEC -> NONE or PREP -> NONE */
+	WARN_ON_ONCE(sta_info_move_smd_state(sta, IEEE80211_STA_SMD_NONE,
+					     notify));
+
+	clear_sta_flag(sta, WLAN_STA_SMD_PREP_TARGET);
+	clear_sta_flag(sta, WLAN_STA_SMD_EXEC_CURRENT);
+	clear_sta_flag(sta, WLAN_STA_SMD_DL_DRAIN);
+}
+
+int sta_info_move_drv_smd_state(struct sta_info *sta)
+{
+	enum ieee80211_sta_smd_state new_ss = sta->smd_state;
+	struct ieee80211_local *local = sta->local;
+	int err = 0;
+
+	if (!test_sta_flag(sta, WLAN_STA_INSERTED))
+		return 0;
+
+	switch (new_ss) {
+	case IEEE80211_STA_SMD_PREP:
+		err = drv_sta_smd_state(local, sta->sdata, &sta->sta,
+					IEEE80211_STA_SMD_NONE,
+					IEEE80211_STA_SMD_PREP);
+		if (err)
+			goto rollback;
+		break;
+	case IEEE80211_STA_SMD_EXEC:
+	case IEEE80211_STA_SMD_DRAIN:
+		err = drv_sta_smd_state(local, sta->sdata, &sta->sta,
+					IEEE80211_STA_SMD_NONE,
+					IEEE80211_STA_SMD_EXEC);
+		if (err)
+			goto rollback;
+
+		if (new_ss == IEEE80211_STA_SMD_DRAIN)
+			err = drv_sta_smd_state(local, sta->sdata, &sta->sta,
+						IEEE80211_STA_SMD_EXEC,
+						IEEE80211_STA_SMD_DRAIN);
+		break;
+	default:
+		return -EINVAL;
+	}
+
+	if (!err)
+		return 0;
+
+	/* if EXEC -> DRAIN failed in the driver, notify EXEC -> NONE */
+	WARN_ON_ONCE(drv_sta_smd_state(local, sta->sdata, &sta->sta,
+				       IEEE80211_STA_SMD_EXEC,
+				       IEEE80211_STA_SMD_NONE));
+
+rollback:
+	sta_info_reset_smd_state(sta, false);
+	return err;
+}
diff --git a/net/mac80211/sta_info.h b/net/mac80211/sta_info.h
index 2e9bb2ab567f..d6b40bc3f404 100644
--- a/net/mac80211/sta_info.h
+++ b/net/mac80211/sta_info.h
@@ -723,6 +723,7 @@ struct ieee80211_sta_removed_link_stats {
  *	would be assigned to link[link_id] where link_id is the id assigned
  *	by the AP.
  * @rem_link_stats: accumulated removed link stats
+ * @smd_state: Sub-state for STAs in SMD BSS Transition
  */
 struct sta_info {
 	/* General information, mostly static */
@@ -799,6 +800,8 @@ struct sta_info {
 	struct link_sta_info __rcu *link[IEEE80211_MLD_MAX_NUM_LINKS];
 	struct ieee80211_sta_removed_link_stats rem_link_stats;
 
+	enum ieee80211_sta_smd_state smd_state;
+
 	/* keep last! */
 	struct ieee80211_sta sta;
 };
@@ -1177,4 +1180,10 @@ static inline u32 sta_stats_encode_rate(struct ieee80211_rx_status *s)
 	return r;
 }
 
+int sta_info_move_smd_state(struct sta_info *sta,
+			    enum ieee80211_sta_smd_state new_ss,
+			    bool notify);
+void sta_info_reset_smd_state(struct sta_info *sta, bool notify);
+int sta_info_move_drv_smd_state(struct sta_info *sta);
+
 #endif /* STA_INFO_H */
diff --git a/net/mac80211/trace.h b/net/mac80211/trace.h
index ea46c3cca21a..83b06e9f72ac 100644
--- a/net/mac80211/trace.h
+++ b/net/mac80211/trace.h
@@ -3431,6 +3431,39 @@ TRACE_EVENT(drv_nan_peer_sched_changed,
 	)
 );
 
+TRACE_EVENT(drv_sta_smd_state,
+	TP_PROTO(struct ieee80211_local *local,
+		 struct ieee80211_sub_if_data *sdata,
+		 struct ieee80211_sta *sta,
+		 enum ieee80211_sta_smd_state old_state,
+		 enum ieee80211_sta_smd_state new_state),
+
+	TP_ARGS(local, sdata, sta, old_state, new_state),
+
+	TP_STRUCT__entry(
+		LOCAL_ENTRY
+		VIF_ENTRY
+		STA_ENTRY
+		__field(u32, old_state)
+		__field(u32, new_state)
+	),
+
+	TP_fast_assign(
+		LOCAL_ASSIGN;
+		VIF_ASSIGN;
+		STA_ASSIGN;
+		__entry->old_state = old_state;
+		__entry->new_state = new_state;
+	),
+
+	TP_printk(
+		LOCAL_PR_FMT VIF_PR_FMT STA_PR_FMT
+		" smd_state: %d->%d",
+		LOCAL_PR_ARG, VIF_PR_ARG, STA_PR_ARG,
+		__entry->old_state, __entry->new_state
+	)
+);
+
 #endif /* !__MAC80211_DRIVER_TRACE || TRACE_HEADER_MULTI_READ */
 
 #undef TRACE_INCLUDE_PATH

-- 
2.34.1