/*
   * Copyright 2012-2013, Marco Porsch <marco.porsch@s2005.tu-chemnitz.de>
   * Copyright 2012-2013, cozybit Inc.
   *
   * This program is free software; you can redistribute it and/or modify
   * it under the terms of the GNU General Public License version 2 as
   * published by the Free Software Foundation.
   */
  
  #include "mesh.h"
  #include "wme.h"
  
  
  /* mesh PS management */
  
  /**
   * mps_qos_null_get - create pre-addressed QoS Null frame for mesh powersave
   */
  static struct sk_buff *mps_qos_null_get(struct sta_info *sta)
  {
  	struct ieee80211_sub_if_data *sdata = sta->sdata;
  	struct ieee80211_local *local = sdata->local;
  	struct ieee80211_hdr *nullfunc; /* use 4addr header */
  	struct sk_buff *skb;
  	int size = sizeof(*nullfunc);
  	__le16 fc;
  
  	skb = dev_alloc_skb(local->hw.extra_tx_headroom + size + 2);
  	if (!skb)
  		return NULL;
  	skb_reserve(skb, local->hw.extra_tx_headroom);
  
  	nullfunc = (struct ieee80211_hdr *) skb_put(skb, size);
  	fc = cpu_to_le16(IEEE80211_FTYPE_DATA | IEEE80211_STYPE_QOS_NULLFUNC);
  	ieee80211_fill_mesh_addresses(nullfunc, &fc, sta->sta.addr,
  				      sdata->vif.addr);
  	nullfunc->frame_control = fc;
  	nullfunc->duration_id = 0;
  	nullfunc->seq_ctrl = 0;
  	/* no address resolution for this frame -> set addr 1 immediately */
  	memcpy(nullfunc->addr1, sta->sta.addr, ETH_ALEN);
  	memset(skb_put(skb, 2), 0, 2); /* append QoS control field */
  	ieee80211_mps_set_frame_flags(sdata, sta, nullfunc);
  
  	return skb;
  }
  
  /**
   * mps_qos_null_tx - send a QoS Null to indicate link-specific power mode
   */
  static void mps_qos_null_tx(struct sta_info *sta)
  {
  	struct sk_buff *skb;
  
  	skb = mps_qos_null_get(sta);
  	if (!skb)
  		return;
  
  	mps_dbg(sta->sdata, "announcing peer-specific power mode to %pM
  ",
  		sta->sta.addr);
  
  	/* don't unintentionally start a MPSP */
  	if (!test_sta_flag(sta, WLAN_STA_PS_STA)) {
  		u8 *qc = ieee80211_get_qos_ctl((void *) skb->data);
  
  		qc[0] |= IEEE80211_QOS_CTL_EOSP;
  	}
  
  	ieee80211_tx_skb(sta->sdata, skb);
  }
  
  /**
   * ieee80211_mps_local_status_update - track status of local link-specific PMs
   *
   * @sdata: local mesh subif
   *
   * sets the non-peer power mode and triggers the driver PS (re-)configuration
   * Return BSS_CHANGED_BEACON if a beacon update is necessary.
   */
  u32 ieee80211_mps_local_status_update(struct ieee80211_sub_if_data *sdata)
  {
  	struct ieee80211_if_mesh *ifmsh = &sdata->u.mesh;
  	struct sta_info *sta;
  	bool peering = false;
  	int light_sleep_cnt = 0;
  	int deep_sleep_cnt = 0;
  	u32 changed = 0;
  	enum nl80211_mesh_power_mode nonpeer_pm;
  
  	rcu_read_lock();
  	list_for_each_entry_rcu(sta, &sdata->local->sta_list, list) {
  		if (sdata != sta->sdata)
  			continue;
  
  		switch (sta->plink_state) {
  		case NL80211_PLINK_OPN_SNT:
  		case NL80211_PLINK_OPN_RCVD:
  		case NL80211_PLINK_CNF_RCVD:
  			peering = true;
  			break;
  		case NL80211_PLINK_ESTAB:
  			if (sta->local_pm == NL80211_MESH_POWER_LIGHT_SLEEP)
  				light_sleep_cnt++;
  			else if (sta->local_pm == NL80211_MESH_POWER_DEEP_SLEEP)
  				deep_sleep_cnt++;
  			break;
  		default:
  			break;
  		}
  	}
  	rcu_read_unlock();
  
  	/*
  	 * Set non-peer mode to active during peering/scanning/authentication
  	 * (see IEEE802.11-2012 13.14.8.3). The non-peer mesh power mode is
  	 * deep sleep if the local STA is in light or deep sleep towards at
  	 * least one mesh peer (see 13.14.3.1). Otherwise, set it to the
  	 * user-configured default value.
  	 */
  	if (peering) {
  		mps_dbg(sdata, "setting non-peer PM to active for peering
  ");
  		nonpeer_pm = NL80211_MESH_POWER_ACTIVE;
  	} else if (light_sleep_cnt || deep_sleep_cnt) {
  		mps_dbg(sdata, "setting non-peer PM to deep sleep
  ");
  		nonpeer_pm = NL80211_MESH_POWER_DEEP_SLEEP;
  	} else {
  		mps_dbg(sdata, "setting non-peer PM to user value
  ");
  		nonpeer_pm = ifmsh->mshcfg.power_mode;
  	}
  
  	/* need update if sleep counts move between 0 and non-zero */
  	if (ifmsh->nonpeer_pm != nonpeer_pm ||
  	    !ifmsh->ps_peers_light_sleep != !light_sleep_cnt ||
  	    !ifmsh->ps_peers_deep_sleep != !deep_sleep_cnt)
  		changed = BSS_CHANGED_BEACON;
  
  	ifmsh->nonpeer_pm = nonpeer_pm;
  	ifmsh->ps_peers_light_sleep = light_sleep_cnt;
  	ifmsh->ps_peers_deep_sleep = deep_sleep_cnt;
  
  	return changed;
  }
  
  /**
   * ieee80211_mps_set_sta_local_pm - set local PM towards a mesh STA
   *
   * @sta: mesh STA
   * @pm: the power mode to set
   * Return BSS_CHANGED_BEACON if a beacon update is in order.
   */
  u32 ieee80211_mps_set_sta_local_pm(struct sta_info *sta,
  				   enum nl80211_mesh_power_mode pm)
  {
  	struct ieee80211_sub_if_data *sdata = sta->sdata;
  
  	if (sta->local_pm == pm)
  		return 0;
  
  	mps_dbg(sdata, "local STA operates in mode %d with %pM
  ",
  		pm, sta->sta.addr);
  
  	sta->local_pm = pm;
  
  	/*
  	 * announce peer-specific power mode transition
  	 * (see IEEE802.11-2012 13.14.3.2 and 13.14.3.3)
  	 */
  	if (sta->plink_state == NL80211_PLINK_ESTAB)
  		mps_qos_null_tx(sta);
  
  	return ieee80211_mps_local_status_update(sdata);
  }
  
  /**
   * ieee80211_mps_set_frame_flags - set mesh PS flags in FC (and QoS Control)
   *
   * @sdata: local mesh subif
   * @sta: mesh STA
   * @hdr: 802.11 frame header
   *
   * see IEEE802.11-2012 8.2.4.1.7 and 8.2.4.5.11
   *
   * NOTE: sta must be given when an individually-addressed QoS frame header
   * is handled, for group-addressed and management frames it is not used
   */
  void ieee80211_mps_set_frame_flags(struct ieee80211_sub_if_data *sdata,
  				   struct sta_info *sta,
  				   struct ieee80211_hdr *hdr)
  {
  	enum nl80211_mesh_power_mode pm;
  	u8 *qc;
  
  	if (WARN_ON(is_unicast_ether_addr(hdr->addr1) &&
  		    ieee80211_is_data_qos(hdr->frame_control) &&
  		    !sta))
  		return;
  
  	if (is_unicast_ether_addr(hdr->addr1) &&
  	    ieee80211_is_data_qos(hdr->frame_control) &&
  	    sta->plink_state == NL80211_PLINK_ESTAB)
  		pm = sta->local_pm;
  	else
  		pm = sdata->u.mesh.nonpeer_pm;
  
  	if (pm == NL80211_MESH_POWER_ACTIVE)
  		hdr->frame_control &= cpu_to_le16(~IEEE80211_FCTL_PM);
  	else
  		hdr->frame_control |= cpu_to_le16(IEEE80211_FCTL_PM);
  
  	if (!ieee80211_is_data_qos(hdr->frame_control))
  		return;
  
  	qc = ieee80211_get_qos_ctl(hdr);
  
  	if ((is_unicast_ether_addr(hdr->addr1) &&
  	     pm == NL80211_MESH_POWER_DEEP_SLEEP) ||
  	    (is_multicast_ether_addr(hdr->addr1) &&
  	     sdata->u.mesh.ps_peers_deep_sleep > 0))
  		qc[1] |= (IEEE80211_QOS_CTL_MESH_PS_LEVEL >> 8);
  	else
  		qc[1] &= ~(IEEE80211_QOS_CTL_MESH_PS_LEVEL >> 8);
  }
  
  /**
   * ieee80211_mps_sta_status_update - update buffering status of neighbor STA
   *
   * @sta: mesh STA
   *
   * called after change of peering status or non-peer/peer-specific power mode
   */
  void ieee80211_mps_sta_status_update(struct sta_info *sta)
  {
  	enum nl80211_mesh_power_mode pm;
  	bool do_buffer;
  
  	/* For non-assoc STA, prevent buffering or frame transmission */
  	if (sta->sta_state < IEEE80211_STA_ASSOC)
  		return;
  
  	/*
  	 * use peer-specific power mode if peering is established and the
  	 * peer's power mode is known
  	 */
  	if (sta->plink_state == NL80211_PLINK_ESTAB &&
  	    sta->peer_pm != NL80211_MESH_POWER_UNKNOWN)
  		pm = sta->peer_pm;
  	else
  		pm = sta->nonpeer_pm;
  
  	do_buffer = (pm != NL80211_MESH_POWER_ACTIVE);
  
  	/* clear the MPSP flags for non-peers or active STA */
  	if (sta->plink_state != NL80211_PLINK_ESTAB) {
  		clear_sta_flag(sta, WLAN_STA_MPSP_OWNER);
  		clear_sta_flag(sta, WLAN_STA_MPSP_RECIPIENT);
  	} else if (!do_buffer) {
  		clear_sta_flag(sta, WLAN_STA_MPSP_OWNER);
  	}
  
  	/* Don't let the same PS state be set twice */
  	if (test_sta_flag(sta, WLAN_STA_PS_STA) == do_buffer)
  		return;
  
  	if (do_buffer) {
  		set_sta_flag(sta, WLAN_STA_PS_STA);
  		atomic_inc(&sta->sdata->u.mesh.ps.num_sta_ps);
  		mps_dbg(sta->sdata, "start PS buffering frames towards %pM
  ",
  			sta->sta.addr);
  	} else {
  		ieee80211_sta_ps_deliver_wakeup(sta);
  	}
  }
  
  static void mps_set_sta_peer_pm(struct sta_info *sta,
  				struct ieee80211_hdr *hdr)
  {
  	enum nl80211_mesh_power_mode pm;
  	u8 *qc = ieee80211_get_qos_ctl(hdr);
  
  	/*
  	 * Test Power Management field of frame control (PW) and
  	 * mesh power save level subfield of QoS control field (PSL)
  	 *
  	 * | PM | PSL| Mesh PM |
  	 * +----+----+---------+
  	 * | 0  |Rsrv|  Active |
  	 * | 1  | 0  |  Light  |
  	 * | 1  | 1  |  Deep   |
  	 */
  	if (ieee80211_has_pm(hdr->frame_control)) {
  		if (qc[1] & (IEEE80211_QOS_CTL_MESH_PS_LEVEL >> 8))
  			pm = NL80211_MESH_POWER_DEEP_SLEEP;
  		else
  			pm = NL80211_MESH_POWER_LIGHT_SLEEP;
  	} else {
  		pm = NL80211_MESH_POWER_ACTIVE;
  	}
  
  	if (sta->peer_pm == pm)
  		return;
  
  	mps_dbg(sta->sdata, "STA %pM enters mode %d
  ",
  		sta->sta.addr, pm);
  
  	sta->peer_pm = pm;
  
  	ieee80211_mps_sta_status_update(sta);
  }
  
  static void mps_set_sta_nonpeer_pm(struct sta_info *sta,
  				   struct ieee80211_hdr *hdr)
  {
  	enum nl80211_mesh_power_mode pm;
  
  	if (ieee80211_has_pm(hdr->frame_control))
  		pm = NL80211_MESH_POWER_DEEP_SLEEP;
  	else
  		pm = NL80211_MESH_POWER_ACTIVE;
  
  	if (sta->nonpeer_pm == pm)
  		return;
  
  	mps_dbg(sta->sdata, "STA %pM sets non-peer mode to %d
  ",
  		sta->sta.addr, pm);
  
  	sta->nonpeer_pm = pm;
  
  	ieee80211_mps_sta_status_update(sta);
  }
  
  /**
   * ieee80211_mps_rx_h_sta_process - frame receive handler for mesh powersave
   *
   * @sta: STA info that transmitted the frame
   * @hdr: IEEE 802.11 (QoS) Header
   */
  void ieee80211_mps_rx_h_sta_process(struct sta_info *sta,
  				    struct ieee80211_hdr *hdr)
  {
  	if (is_unicast_ether_addr(hdr->addr1) &&
  	    ieee80211_is_data_qos(hdr->frame_control)) {
  		/*
  		 * individually addressed QoS Data/Null frames contain
  		 * peer link-specific PS mode towards the local STA
  		 */
  		mps_set_sta_peer_pm(sta, hdr);
  
  		/* check for mesh Peer Service Period trigger frames */
  		ieee80211_mpsp_trigger_process(ieee80211_get_qos_ctl(hdr),
  					       sta, false, false);
  	} else {
  		/*
  		 * can only determine non-peer PS mode
  		 * (see IEEE802.11-2012 8.2.4.1.7)
  		 */
  		mps_set_sta_nonpeer_pm(sta, hdr);
  	}
  }
  
  
  /* mesh PS frame release */
  
  static void mpsp_trigger_send(struct sta_info *sta, bool rspi, bool eosp)
  {
  	struct ieee80211_sub_if_data *sdata = sta->sdata;
  	struct sk_buff *skb;
  	struct ieee80211_hdr *nullfunc;
  	struct ieee80211_tx_info *info;
  	u8 *qc;
  
  	skb = mps_qos_null_get(sta);
  	if (!skb)
  		return;
  
  	nullfunc = (struct ieee80211_hdr *) skb->data;
  	if (!eosp)
  		nullfunc->frame_control |=
  				cpu_to_le16(IEEE80211_FCTL_MOREDATA);
  	/*
  	 * | RSPI | EOSP |  MPSP triggering   |
  	 * +------+------+--------------------+
  	 * |  0   |  0   | local STA is owner |
  	 * |  0   |  1   | no MPSP (MPSP end) |
  	 * |  1   |  0   | both STA are owner |
  	 * |  1   |  1   | peer STA is owner  | see IEEE802.11-2012 13.14.9.2
  	 */
  	qc = ieee80211_get_qos_ctl(nullfunc);
  	if (rspi)
  		qc[1] |= (IEEE80211_QOS_CTL_RSPI >> 8);
  	if (eosp)
  		qc[0] |= IEEE80211_QOS_CTL_EOSP;
  
  	info = IEEE80211_SKB_CB(skb);
  
  	info->flags |= IEEE80211_TX_CTL_NO_PS_BUFFER |
  		       IEEE80211_TX_CTL_REQ_TX_STATUS;
  
  	mps_dbg(sdata, "sending MPSP trigger%s%s to %pM
  ",
  		rspi ? " RSPI" : "", eosp ? " EOSP" : "", sta->sta.addr);
  
  	ieee80211_tx_skb(sdata, skb);
  }
  
  /**
   * mpsp_qos_null_append - append QoS Null frame to MPSP skb queue if needed
   *
   * To properly end a mesh MPSP the last transmitted frame has to set the EOSP
   * flag in the QoS Control field. In case the current tailing frame is not a
   * QoS Data frame, append a QoS Null to carry the flag.
   */
  static void mpsp_qos_null_append(struct sta_info *sta,
  				 struct sk_buff_head *frames)
  {
  	struct ieee80211_sub_if_data *sdata = sta->sdata;
  	struct sk_buff *new_skb, *skb = skb_peek_tail(frames);
  	struct ieee80211_hdr *hdr = (struct ieee80211_hdr *) skb->data;
  	struct ieee80211_tx_info *info;
  
  	if (ieee80211_is_data_qos(hdr->frame_control))
  		return;
  
  	new_skb = mps_qos_null_get(sta);
  	if (!new_skb)
  		return;
  
  	mps_dbg(sdata, "appending QoS Null in MPSP towards %pM
  ",
  		sta->sta.addr);
  	/*
  	 * This frame has to be transmitted last. Assign lowest priority to
  	 * make sure it cannot pass other frames when releasing multiple ACs.
  	 */
  	new_skb->priority = 1;
  	skb_set_queue_mapping(new_skb, IEEE80211_AC_BK);
  	ieee80211_set_qos_hdr(sdata, new_skb);
  
  	info = IEEE80211_SKB_CB(new_skb);
  	info->control.vif = &sdata->vif;
  	info->flags |= IEEE80211_TX_INTFL_NEED_TXPROCESSING;
  
  	__skb_queue_tail(frames, new_skb);
  }
  
  /**
   * mps_frame_deliver - transmit frames during mesh powersave
   *
   * @sta: STA info to transmit to
   * @n_frames: number of frames to transmit. -1 for all
   */
  static void mps_frame_deliver(struct sta_info *sta, int n_frames)
  {
  	struct ieee80211_local *local = sta->sdata->local;
  	int ac;
  	struct sk_buff_head frames;
  	struct sk_buff *skb;
  	bool more_data = false;
  
  	skb_queue_head_init(&frames);
  
  	/* collect frame(s) from buffers */
  	for (ac = 0; ac < IEEE80211_NUM_ACS; ac++) {
  		while (n_frames != 0) {
  			skb = skb_dequeue(&sta->tx_filtered[ac]);
  			if (!skb) {
  				skb = skb_dequeue(
  					&sta->ps_tx_buf[ac]);
  				if (skb)
  					local->total_ps_buffered--;
  			}
  			if (!skb)
  				break;
  			n_frames--;
  			__skb_queue_tail(&frames, skb);
  		}
  
  		if (!skb_queue_empty(&sta->tx_filtered[ac]) ||
  		    !skb_queue_empty(&sta->ps_tx_buf[ac]))
  			more_data = true;
  	}
  
  	/* nothing to send? -> EOSP */
  	if (skb_queue_empty(&frames)) {
  		mpsp_trigger_send(sta, false, true);
  		return;
  	}
  
  	/* in a MPSP make sure the last skb is a QoS Data frame */
  	if (test_sta_flag(sta, WLAN_STA_MPSP_OWNER))
  		mpsp_qos_null_append(sta, &frames);
  
  	mps_dbg(sta->sdata, "sending %d frames to PS STA %pM
  ",
  		skb_queue_len(&frames), sta->sta.addr);
  
  	/* prepare collected frames for transmission */
  	skb_queue_walk(&frames, skb) {
  		struct ieee80211_tx_info *info = IEEE80211_SKB_CB(skb);
  		struct ieee80211_hdr *hdr = (void *) skb->data;
  
  		/*
  		 * Tell TX path to send this frame even though the
  		 * STA may still remain is PS mode after this frame
  		 * exchange.
  		 */
  		info->flags |= IEEE80211_TX_CTL_NO_PS_BUFFER;
  
  		if (more_data || !skb_queue_is_last(&frames, skb))
  			hdr->frame_control |=
  				cpu_to_le16(IEEE80211_FCTL_MOREDATA);
  		else
  			hdr->frame_control &=
  				cpu_to_le16(~IEEE80211_FCTL_MOREDATA);
  
  		if (skb_queue_is_last(&frames, skb) &&
  		    ieee80211_is_data_qos(hdr->frame_control)) {
  			u8 *qoshdr = ieee80211_get_qos_ctl(hdr);
  
  			/* MPSP trigger frame ends service period */
  			*qoshdr |= IEEE80211_QOS_CTL_EOSP;
  			info->flags |= IEEE80211_TX_CTL_REQ_TX_STATUS;
  		}
  	}
  
  	ieee80211_add_pending_skbs(local, &frames);
  	sta_info_recalc_tim(sta);
  }
  
  /**
   * ieee80211_mpsp_trigger_process - track status of mesh Peer Service Periods
   *
   * @qc: QoS Control field
   * @sta: peer to start a MPSP with
   * @tx: frame was transmitted by the local STA
   * @acked: frame has been transmitted successfully
   *
   * NOTE: active mode STA may only serve as MPSP owner
   */
  void ieee80211_mpsp_trigger_process(u8 *qc, struct sta_info *sta,
  				    bool tx, bool acked)
  {
  	u8 rspi = qc[1] & (IEEE80211_QOS_CTL_RSPI >> 8);
  	u8 eosp = qc[0] & IEEE80211_QOS_CTL_EOSP;
  
  	if (tx) {
  		if (rspi && acked)
  			set_sta_flag(sta, WLAN_STA_MPSP_RECIPIENT);
  
  		if (eosp)
  			clear_sta_flag(sta, WLAN_STA_MPSP_OWNER);
  		else if (acked &&
  			 test_sta_flag(sta, WLAN_STA_PS_STA) &&
  			 !test_and_set_sta_flag(sta, WLAN_STA_MPSP_OWNER))
  			mps_frame_deliver(sta, -1);
  	} else {
  		if (eosp)
  			clear_sta_flag(sta, WLAN_STA_MPSP_RECIPIENT);
  		else if (sta->local_pm != NL80211_MESH_POWER_ACTIVE)
  			set_sta_flag(sta, WLAN_STA_MPSP_RECIPIENT);
  
  		if (rspi && !test_and_set_sta_flag(sta, WLAN_STA_MPSP_OWNER))
  			mps_frame_deliver(sta, -1);
  	}
  }
  
  /**
   * ieee80211_mps_frame_release - release frames buffered due to mesh power save
   *
   * @sta: mesh STA
   * @elems: IEs of beacon or probe response
   *
   * For peers if we have individually-addressed frames buffered or the peer
   * indicates buffered frames, send a corresponding MPSP trigger frame. Since
   * we do not evaluate the awake window duration, QoS Nulls are used as MPSP
   * trigger frames. If the neighbour STA is not a peer, only send single frames.
   */
  void ieee80211_mps_frame_release(struct sta_info *sta,
  				 struct ieee802_11_elems *elems)
  {
  	int ac, buffer_local = 0;
  	bool has_buffered = false;
  
  	if (sta->plink_state == NL80211_PLINK_ESTAB)
  		has_buffered = ieee80211_check_tim(elems->tim, elems->tim_len,
  						   sta->llid);
  
  	if (has_buffered)
  		mps_dbg(sta->sdata, "%pM indicates buffered frames
  ",
  			sta->sta.addr);
  
  	/* only transmit to PS STA with announced, non-zero awake window */
  	if (test_sta_flag(sta, WLAN_STA_PS_STA) &&
  	    (!elems->awake_window || !le16_to_cpu(*elems->awake_window)))
  		return;
  
  	if (!test_sta_flag(sta, WLAN_STA_MPSP_OWNER))
  		for (ac = 0; ac < IEEE80211_NUM_ACS; ac++)
  			buffer_local += skb_queue_len(&sta->ps_tx_buf[ac]) +
  					skb_queue_len(&sta->tx_filtered[ac]);
  
  	if (!has_buffered && !buffer_local)
  		return;
  
  	if (sta->plink_state == NL80211_PLINK_ESTAB)
  		mpsp_trigger_send(sta, has_buffered, !buffer_local);
  	else
  		mps_frame_deliver(sta, 1);
  }