mac80211: define TDLS wider BW support bits

Allow a device to specify support for the TDLS wider-bandwidth feature.
Indicate this support during TDLS setup in the ext-capab IE and set an
appropriate station flag when our TDLS peer supports it.
This feature gives TDLS peers the ability to use a wider channel than
the base width of the BSS. For instance VHT capable TDLS peers connected
on a 20MHz channel can extend the channel to 80MHz, if regulatory
considerations allow it.

Do not cap the bandwidth of such stations by the current BSS channel width
in mac80211.

Signed-off-by: Arik Nemtsov <[e-mail]>
Signed-off-by: Emmanuel Grumbach <[e-mail]>
Signed-off-by: Johannes Berg <[e-mail]>

include/net/mac80211.h

···
  * @IEEE80211_HW_SINGLE_SCAN_ON_ALL_BANDS: The HW supports scanning on all bands
  *	in one command, mac80211 doesn't have to run separate scans per band.
  *
+ * @IEEE80211_HW_TDLS_WIDER_BW: The device/driver supports wider bandwidth
+ *	than then BSS bandwidth for a TDLS link on the base channel.
+ *
  * @NUM_IEEE80211_HW_FLAGS: number of hardware flags, used for sizing arrays
  */
 enum ieee80211_hw_flags {
···
 	IEEE80211_HW_CHANCTX_STA_CSA,
 	IEEE80211_HW_SUPPORTS_CLONED_SKBS,
 	IEEE80211_HW_SINGLE_SCAN_ON_ALL_BANDS,
+	IEEE80211_HW_TDLS_WIDER_BW,
 
 	/* keep last, obviously */
 	NUM_IEEE80211_HW_FLAGS

net/mac80211/cfg.c

···
 	    params->ext_capab[3] & WLAN_EXT_CAPA4_TDLS_CHAN_SWITCH)
 		set_sta_flag(sta, WLAN_STA_TDLS_CHAN_SWITCH);
 
+	if (test_sta_flag(sta, WLAN_STA_TDLS_PEER) &&
+	    ieee80211_hw_check(&local->hw, TDLS_WIDER_BW) &&
+	    params->ext_capab_len >= 8 &&
+	    params->ext_capab[7] & WLAN_EXT_CAPA8_TDLS_WIDE_BW_ENABLED)
+		set_sta_flag(sta, WLAN_STA_TDLS_WIDER_BW);
+
 	if (params->sta_modify_mask & STATION_PARAM_APPLY_UAPSD) {
 		sta->sta.uapsd_queues = params->uapsd_queues;
 		sta->sta.max_sp = params->max_sp;

net/mac80211/debugfs.c

···
 	FLAG(CHANCTX_STA_CSA),
 	FLAG(SUPPORTS_CLONED_SKBS),
 	FLAG(SINGLE_SCAN_ON_ALL_BANDS),
+	FLAG(TDLS_WIDER_BW),
 
 	/* keep last for the build bug below */
 	(void *)0x1

net/mac80211/sta_info.h

···
  * @WLAN_STA_TDLS_CHAN_SWITCH: This TDLS peer supports TDLS channel-switching
  * @WLAN_STA_TDLS_OFF_CHANNEL: The local STA is currently off-channel with this
  *	TDLS peer
+ * @WLAN_STA_TDLS_WIDER_BW: This TDLS peer supports working on a wider bw on
+ *	the BSS base channel.
  * @WLAN_STA_UAPSD: Station requested unscheduled SP while driver was
  *	keeping station in power-save mode, reply when the driver
  *	unblocks the station.
···
 	WLAN_STA_TDLS_INITIATOR,
 	WLAN_STA_TDLS_CHAN_SWITCH,
 	WLAN_STA_TDLS_OFF_CHANNEL,
+	WLAN_STA_TDLS_WIDER_BW,
 	WLAN_STA_UAPSD,
 	WLAN_STA_SP,
 	WLAN_STA_4ADDR_EVENT,

net/mac80211/tdls.c

···
 	mutex_unlock(&local->mtx);
 }
 
-static void ieee80211_tdls_add_ext_capab(struct ieee80211_local *local,
+static void ieee80211_tdls_add_ext_capab(struct ieee80211_sub_if_data *sdata,
 					 struct sk_buff *skb)
 {
-	u8 *pos = (void *)skb_put(skb, 7);
+	struct ieee80211_local *local = sdata->local;
 	bool chan_switch = local->hw.wiphy->features &
 			   NL80211_FEATURE_TDLS_CHANNEL_SWITCH;
+	bool wider_band = ieee80211_hw_check(&local->hw, TDLS_WIDER_BW);
+	enum ieee80211_band band = ieee80211_get_sdata_band(sdata);
+	struct ieee80211_supported_band *sband = local->hw.wiphy->bands[band];
+	bool vht = sband && sband->vht_cap.vht_supported;
+	u8 *pos = (void *)skb_put(skb, 10);
 
 	*pos++ = WLAN_EID_EXT_CAPABILITY;
-	*pos++ = 5; /* len */
+	*pos++ = 8; /* len */
 	*pos++ = 0x0;
 	*pos++ = 0x0;
 	*pos++ = 0x0;
 	*pos++ = chan_switch ? WLAN_EXT_CAPA4_TDLS_CHAN_SWITCH : 0;
 	*pos++ = WLAN_EXT_CAPA5_TDLS_ENABLED;
+	*pos++ = 0;
+	*pos++ = 0;
+	*pos++ = (vht && wider_band) ? WLAN_EXT_CAPA8_TDLS_WIDE_BW_ENABLED : 0;
 }
 
 static u8
···
 		offset = noffset;
 	}
 
-	ieee80211_tdls_add_ext_capab(local, skb);
+	ieee80211_tdls_add_ext_capab(sdata, skb);
 
 	/* add the QoS element if we support it */
 	if (local->hw.queues >= IEEE80211_NUM_ACS &&
···
 			       max(sizeof(struct ieee80211_mgmt),
 				   sizeof(struct ieee80211_tdls_data)) +
 			       50 + /* supported rates */
-			       7 + /* ext capab */
+			       10 + /* ext capab */
 			       26 + /* max(WMM-info, WMM-param) */
 			       2 + max(sizeof(struct ieee80211_ht_cap),
 				       sizeof(struct ieee80211_ht_operation)) +

net/mac80211/vht.c

···
 {
 	struct ieee80211_sub_if_data *sdata = sta->sdata;
 	enum ieee80211_sta_rx_bandwidth bw;
+	enum nl80211_chan_width bss_width = sdata->vif.bss_conf.chandef.width;
 
-	bw = ieee80211_chan_width_to_rx_bw(sdata->vif.bss_conf.chandef.width);
-	bw = min(bw, ieee80211_sta_cap_rx_bw(sta));
+	bw = ieee80211_sta_cap_rx_bw(sta);
 	bw = min(bw, sta->cur_max_bandwidth);
+
+	/* do not cap the BW of TDLS WIDER_BW peers by the bss */
+	if (!test_sta_flag(sta, WLAN_STA_TDLS_WIDER_BW))
+		bw = min(bw, ieee80211_chan_width_to_rx_bw(bss_width));
 
 	return bw;
 }