mac80211: implement SMPS for AP

When the driver requests to move to STATIC or DYNAMIC SMPS,
we send an action frame to each associated station and
reconfigure the channel context / driver.
Of course, non-MIMO stations are ignored.

The beacon isn't updated. The association response will
include the original capabilities. Stations that associate
while in non-OFF SMPS mode will get an action frame right
after association to inform them about our current state.
Note that we wait until the end of the EAPOL. Sending an
action frame before the EAPOL is finished can be an issue
for a few clients. Clients aren't likely to send EAPOL
frames in MIMO anyway.

When the SMPS configuration gets more permissive (e.g.
STATIC -> OFF), we don't wake up stations that are asleep
We remember that they don't know about the change and send
the action frame when they wake up.

When the SMPS configuration gets more restrictive (e.g.
OFF -> STATIC), we set the TIM bit for every sleeping STA.
uAPSD stations might send MIMO until they poll the action
frame, but this is for a short period of time.

Signed-off-by: Emmanuel Grumbach <emmanuel.grumbach@intel.com>
[fix vht streams loop, initialisation]
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

1 files changed, 72 insertions, 0 deletions

diff --git a/net/mac80211/sta_info.c b/net/mac80211/sta_info.c
index aeb967a..1eb66e2 100644
--- a/net/mac80211/sta_info.c
+++ b/net/mac80211/sta_info.c
@@ -385,6 +385,30 @@ struct sta_info *sta_info_alloc(struct ieee80211_sub_if_data *sdata,
 		sta->last_seq_ctrl[i] = cpu_to_le16(USHRT_MAX);
 
 	sta->sta.smps_mode = IEEE80211_SMPS_OFF;
+	if (sdata->vif.type == NL80211_IFTYPE_AP ||
+	    sdata->vif.type == NL80211_IFTYPE_AP_VLAN) {
+		struct ieee80211_supported_band *sband =
+			local->hw.wiphy->bands[ieee80211_get_sdata_band(sdata)];
+		u8 smps = (sband->ht_cap.cap & IEEE80211_HT_CAP_SM_PS) >>
+				IEEE80211_HT_CAP_SM_PS_SHIFT;
+		/*
+		 * Assume that hostapd advertises our caps in the beacon and
+		 * this is the known_smps_mode for a station that just assciated
+		 */
+		switch (smps) {
+		case WLAN_HT_SMPS_CONTROL_DISABLED:
+			sta->known_smps_mode = IEEE80211_SMPS_OFF;
+			break;
+		case WLAN_HT_SMPS_CONTROL_STATIC:
+			sta->known_smps_mode = IEEE80211_SMPS_STATIC;
+			break;
+		case WLAN_HT_SMPS_CONTROL_DYNAMIC:
+			sta->known_smps_mode = IEEE80211_SMPS_DYNAMIC;
+			break;
+		default:
+			WARN_ON(1);
+		}
+	}
 
 	sta_dbg(sdata, "Allocated STA %pM\n", sta->sta.addr);
 
@@ -1069,6 +1093,19 @@ void ieee80211_sta_ps_deliver_wakeup(struct sta_info *sta)
 
 	ieee80211_add_pending_skbs_fn(local, &pending, clear_sta_ps_flags, sta);
 
+	/* This station just woke up and isn't aware of our SMPS state */
+	if (!ieee80211_smps_is_restrictive(sta->known_smps_mode,
+					   sdata->smps_mode) &&
+	    sta->known_smps_mode != sdata->bss->req_smps &&
+	    sta_info_tx_streams(sta) != 1) {
+		ht_dbg(sdata,
+		       "%pM just woke up and MIMO capable - update SMPS\n",
+		       sta->sta.addr);
+		ieee80211_send_smps_action(sdata, sdata->bss->req_smps,
+					   sta->sta.addr,
+					   sdata->vif.bss_conf.bssid);
+	}
+
 	local->total_ps_buffered -= buffered;
 
 	sta_info_recalc_tim(sta);
@@ -1520,3 +1557,38 @@ int sta_info_move_state(struct sta_info *sta,
 
 	return 0;
 }
+
+u8 sta_info_tx_streams(struct sta_info *sta)
+{
+	struct ieee80211_sta_ht_cap *ht_cap = &sta->sta.ht_cap;
+	u8 rx_streams;
+
+	if (!sta->sta.ht_cap.ht_supported)
+		return 1;
+
+	if (sta->sta.vht_cap.vht_supported) {
+		int i;
+		u16 tx_mcs_map =
+			le16_to_cpu(sta->sta.vht_cap.vht_mcs.tx_mcs_map);
+
+		for (i = 7; i >= 0; i--)
+			if ((tx_mcs_map & (0x3 << (i * 2))) !=
+			    IEEE80211_VHT_MCS_NOT_SUPPORTED)
+				return i + 1;
+	}
+
+	if (ht_cap->mcs.rx_mask[3])
+		rx_streams = 4;
+	else if (ht_cap->mcs.rx_mask[2])
+		rx_streams = 3;
+	else if (ht_cap->mcs.rx_mask[1])
+		rx_streams = 2;
+	else
+		rx_streams = 1;
+
+	if (!(ht_cap->mcs.tx_params & IEEE80211_HT_MCS_TX_RX_DIFF))
+		return rx_streams;
+
+	return ((ht_cap->mcs.tx_params & IEEE80211_HT_MCS_TX_MAX_STREAMS_MASK)
+			>> IEEE80211_HT_MCS_TX_MAX_STREAMS_SHIFT) + 1;
+}