/*
   * HT handling
   *
   * Copyright 2003, Jouni Malinen <jkmaline@cc.hut.fi>
   * Copyright 2002-2005, Instant802 Networks, Inc.
   * Copyright 2005-2006, Devicescape Software, Inc.
   * Copyright 2006-2007	Jiri Benc <jbenc@suse.cz>
   * Copyright 2007, Michael Wu <flamingice@sourmilk.net>
   * Copyright 2007-2010, Intel Corporation
   *
   * 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.
   */
  
  /**
   * DOC: RX A-MPDU aggregation
   *
   * Aggregation on the RX side requires only implementing the
   * @ampdu_action callback that is invoked to start/stop any
   * block-ack sessions for RX aggregation.
   *
   * When RX aggregation is started by the peer, the driver is
   * notified via @ampdu_action function, with the
   * %IEEE80211_AMPDU_RX_START action, and may reject the request
   * in which case a negative response is sent to the peer, if it
   * accepts it a positive response is sent.
   *
   * While the session is active, the device/driver are required
   * to de-aggregate frames and pass them up one by one to mac80211,
   * which will handle the reorder buffer.
   *
   * When the aggregation session is stopped again by the peer or
   * ourselves, the driver's @ampdu_action function will be called
   * with the action %IEEE80211_AMPDU_RX_STOP. In this case, the
   * call must not fail.
   */
  
  #include <linux/ieee80211.h>
  #include <linux/slab.h>
  #include <linux/export.h>
  #include <net/mac80211.h>
  #include "ieee80211_i.h"
  #include "driver-ops.h"
  
  static void ieee80211_free_tid_rx(struct rcu_head *h)
  {
  	struct tid_ampdu_rx *tid_rx =
  		container_of(h, struct tid_ampdu_rx, rcu_head);
  	int i;
  
  	del_timer_sync(&tid_rx->reorder_timer);
  
  	for (i = 0; i < tid_rx->buf_size; i++)
  		dev_kfree_skb(tid_rx->reorder_buf[i]);
  	kfree(tid_rx->reorder_buf);
  	kfree(tid_rx->reorder_time);
  	kfree(tid_rx);
  }
  
  void ___ieee80211_stop_rx_ba_session(struct sta_info *sta, u16 tid,
  				     u16 initiator, u16 reason, bool tx)
  {
  	struct ieee80211_local *local = sta->local;
  	struct tid_ampdu_rx *tid_rx;
  
  	lockdep_assert_held(&sta->ampdu_mlme.mtx);
  
  	tid_rx = rcu_dereference_protected(sta->ampdu_mlme.tid_rx[tid],
  					lockdep_is_held(&sta->ampdu_mlme.mtx));
  
  	if (!tid_rx)
  		return;
  
  	RCU_INIT_POINTER(sta->ampdu_mlme.tid_rx[tid], NULL);
  
  	ht_dbg(sta->sdata,
  	       "Rx BA session stop requested for %pM tid %u %s reason: %d
  ",
  	       sta->sta.addr, tid,
  	       initiator == WLAN_BACK_RECIPIENT ? "recipient" : "inititator",
  	       (int)reason);
  
  	if (drv_ampdu_action(local, sta->sdata, IEEE80211_AMPDU_RX_STOP,
  			     &sta->sta, tid, NULL, 0))
  		sdata_info(sta->sdata,
  			   "HW problem - can not stop rx aggregation for %pM tid %d
  ",
  			   sta->sta.addr, tid);
  
  	/* check if this is a self generated aggregation halt */
  	if (initiator == WLAN_BACK_RECIPIENT && tx)
  		ieee80211_send_delba(sta->sdata, sta->sta.addr,
  				     tid, WLAN_BACK_RECIPIENT, reason);
  
  	del_timer_sync(&tid_rx->session_timer);
  
  	call_rcu(&tid_rx->rcu_head, ieee80211_free_tid_rx);
  }
  
  void __ieee80211_stop_rx_ba_session(struct sta_info *sta, u16 tid,
  				    u16 initiator, u16 reason, bool tx)
  {
  	mutex_lock(&sta->ampdu_mlme.mtx);
  	___ieee80211_stop_rx_ba_session(sta, tid, initiator, reason, tx);
  	mutex_unlock(&sta->ampdu_mlme.mtx);
  }
  
  void ieee80211_stop_rx_ba_session(struct ieee80211_vif *vif, u16 ba_rx_bitmap,
  				  const u8 *addr)
  {
  	struct ieee80211_sub_if_data *sdata = vif_to_sdata(vif);
  	struct sta_info *sta;
  	int i;
  
  	rcu_read_lock();
  	sta = sta_info_get_bss(sdata, addr);
  	if (!sta) {
  		rcu_read_unlock();
  		return;
  	}
  
  	for (i = 0; i < IEEE80211_NUM_TIDS; i++)
  		if (ba_rx_bitmap & BIT(i))
  			set_bit(i, sta->ampdu_mlme.tid_rx_stop_requested);
  
  	ieee80211_queue_work(&sta->local->hw, &sta->ampdu_mlme.work);
  	rcu_read_unlock();
  }
  EXPORT_SYMBOL(ieee80211_stop_rx_ba_session);
  
  /*
   * After accepting the AddBA Request we activated a timer,
   * resetting it after each frame that arrives from the originator.
   */
  static void sta_rx_agg_session_timer_expired(unsigned long data)
  {
  	/* not an elegant detour, but there is no choice as the timer passes
  	 * only one argument, and various sta_info are needed here, so init
  	 * flow in sta_info_create gives the TID as data, while the timer_to_id
  	 * array gives the sta through container_of */
  	u8 *ptid = (u8 *)data;
  	u8 *timer_to_id = ptid - *ptid;
  	struct sta_info *sta = container_of(timer_to_id, struct sta_info,
  					 timer_to_tid[0]);
  	struct tid_ampdu_rx *tid_rx;
  	unsigned long timeout;
  
  	rcu_read_lock();
  	tid_rx = rcu_dereference(sta->ampdu_mlme.tid_rx[*ptid]);
  	if (!tid_rx) {
  		rcu_read_unlock();
  		return;
  	}
  
  	timeout = tid_rx->last_rx + TU_TO_JIFFIES(tid_rx->timeout);
  	if (time_is_after_jiffies(timeout)) {
  		mod_timer(&tid_rx->session_timer, timeout);
  		rcu_read_unlock();
  		return;
  	}
  	rcu_read_unlock();
  
  	ht_dbg(sta->sdata, "RX session timer expired on %pM tid %d
  ",
  	       sta->sta.addr, (u16)*ptid);
  
  	set_bit(*ptid, sta->ampdu_mlme.tid_rx_timer_expired);
  	ieee80211_queue_work(&sta->local->hw, &sta->ampdu_mlme.work);
  }
  
  static void sta_rx_agg_reorder_timer_expired(unsigned long data)
  {
  	u8 *ptid = (u8 *)data;
  	u8 *timer_to_id = ptid - *ptid;
  	struct sta_info *sta = container_of(timer_to_id, struct sta_info,
  			timer_to_tid[0]);
  
  	rcu_read_lock();
  	ieee80211_release_reorder_timeout(sta, *ptid);
  	rcu_read_unlock();
  }
  
  static void ieee80211_send_addba_resp(struct ieee80211_sub_if_data *sdata, u8 *da, u16 tid,
  				      u8 dialog_token, u16 status, u16 policy,
  				      u16 buf_size, u16 timeout)
  {
  	struct ieee80211_local *local = sdata->local;
  	struct sk_buff *skb;
  	struct ieee80211_mgmt *mgmt;
  	u16 capab;
  
  	skb = dev_alloc_skb(sizeof(*mgmt) + local->hw.extra_tx_headroom);
  	if (!skb)
  		return;
  
  	skb_reserve(skb, local->hw.extra_tx_headroom);
  	mgmt = (struct ieee80211_mgmt *) skb_put(skb, 24);
  	memset(mgmt, 0, 24);
  	memcpy(mgmt->da, da, ETH_ALEN);
  	memcpy(mgmt->sa, sdata->vif.addr, ETH_ALEN);
  	if (sdata->vif.type == NL80211_IFTYPE_AP ||
  	    sdata->vif.type == NL80211_IFTYPE_AP_VLAN ||
  	    sdata->vif.type == NL80211_IFTYPE_MESH_POINT)
  		memcpy(mgmt->bssid, sdata->vif.addr, ETH_ALEN);
  	else if (sdata->vif.type == NL80211_IFTYPE_STATION)
  		memcpy(mgmt->bssid, sdata->u.mgd.bssid, ETH_ALEN);
  	else if (sdata->vif.type == NL80211_IFTYPE_ADHOC)
  		memcpy(mgmt->bssid, sdata->u.ibss.bssid, ETH_ALEN);
  
  	mgmt->frame_control = cpu_to_le16(IEEE80211_FTYPE_MGMT |
  					  IEEE80211_STYPE_ACTION);
  
  	skb_put(skb, 1 + sizeof(mgmt->u.action.u.addba_resp));
  	mgmt->u.action.category = WLAN_CATEGORY_BACK;
  	mgmt->u.action.u.addba_resp.action_code = WLAN_ACTION_ADDBA_RESP;
  	mgmt->u.action.u.addba_resp.dialog_token = dialog_token;
  
  	capab = (u16)(policy << 1);	/* bit 1 aggregation policy */
  	capab |= (u16)(tid << 2); 	/* bit 5:2 TID number */
  	capab |= (u16)(buf_size << 6);	/* bit 15:6 max size of aggregation */
  
  	mgmt->u.action.u.addba_resp.capab = cpu_to_le16(capab);
  	mgmt->u.action.u.addba_resp.timeout = cpu_to_le16(timeout);
  	mgmt->u.action.u.addba_resp.status = cpu_to_le16(status);
  
  	ieee80211_tx_skb(sdata, skb);
  }
  
  void ieee80211_process_addba_request(struct ieee80211_local *local,
  				     struct sta_info *sta,
  				     struct ieee80211_mgmt *mgmt,
  				     size_t len)
  {
  	struct tid_ampdu_rx *tid_agg_rx;
  	u16 capab, tid, timeout, ba_policy, buf_size, start_seq_num, status;
  	u8 dialog_token;
  	int ret = -EOPNOTSUPP;
  
  	/* extract session parameters from addba request frame */
  	dialog_token = mgmt->u.action.u.addba_req.dialog_token;
  	timeout = le16_to_cpu(mgmt->u.action.u.addba_req.timeout);
  	start_seq_num =
  		le16_to_cpu(mgmt->u.action.u.addba_req.start_seq_num) >> 4;
  
  	capab = le16_to_cpu(mgmt->u.action.u.addba_req.capab);
  	ba_policy = (capab & IEEE80211_ADDBA_PARAM_POLICY_MASK) >> 1;
  	tid = (capab & IEEE80211_ADDBA_PARAM_TID_MASK) >> 2;
  	buf_size = (capab & IEEE80211_ADDBA_PARAM_BUF_SIZE_MASK) >> 6;
  
  	status = WLAN_STATUS_REQUEST_DECLINED;
  
  	if (test_sta_flag(sta, WLAN_STA_BLOCK_BA)) {
  		ht_dbg(sta->sdata,
  		       "Suspend in progress - Denying ADDBA request (%pM tid %d)
  ",
  		       sta->sta.addr, tid);
  		goto end_no_lock;
  	}
  
  	/* sanity check for incoming parameters:
  	 * check if configuration can support the BA policy
  	 * and if buffer size does not exceeds max value */
  	/* XXX: check own ht delayed BA capability?? */
  	if (((ba_policy != 1) &&
  	     (!(sta->sta.ht_cap.cap & IEEE80211_HT_CAP_DELAY_BA))) ||
  	    (buf_size > IEEE80211_MAX_AMPDU_BUF)) {
  		status = WLAN_STATUS_INVALID_QOS_PARAM;
  		ht_dbg_ratelimited(sta->sdata,
  				   "AddBA Req with bad params from %pM on tid %u. policy %d, buffer size %d
  ",
  				   mgmt->sa, tid, ba_policy, buf_size);
  		goto end_no_lock;
  	}
  	/* determine default buffer size */
  	if (buf_size == 0)
  		buf_size = IEEE80211_MAX_AMPDU_BUF;
  
  	/* make sure the size doesn't exceed the maximum supported by the hw */
  	if (buf_size > local->hw.max_rx_aggregation_subframes)
  		buf_size = local->hw.max_rx_aggregation_subframes;
  
  	/* examine state machine */
  	mutex_lock(&sta->ampdu_mlme.mtx);
  
  	if (sta->ampdu_mlme.tid_rx[tid]) {
  		ht_dbg_ratelimited(sta->sdata,
  				   "unexpected AddBA Req from %pM on tid %u
  ",
  				   mgmt->sa, tid);
  
  		/* delete existing Rx BA session on the same tid */
  		___ieee80211_stop_rx_ba_session(sta, tid, WLAN_BACK_RECIPIENT,
  						WLAN_STATUS_UNSPECIFIED_QOS,
  						false);
  	}
  
  	/* prepare A-MPDU MLME for Rx aggregation */
  	tid_agg_rx = kmalloc(sizeof(struct tid_ampdu_rx), GFP_KERNEL);
  	if (!tid_agg_rx)
  		goto end;
  
  	spin_lock_init(&tid_agg_rx->reorder_lock);
  
  	/* rx timer */
  	tid_agg_rx->session_timer.function = sta_rx_agg_session_timer_expired;
  	tid_agg_rx->session_timer.data = (unsigned long)&sta->timer_to_tid[tid];
  	init_timer_deferrable(&tid_agg_rx->session_timer);
  
  	/* rx reorder timer */
  	tid_agg_rx->reorder_timer.function = sta_rx_agg_reorder_timer_expired;
  	tid_agg_rx->reorder_timer.data = (unsigned long)&sta->timer_to_tid[tid];
  	init_timer(&tid_agg_rx->reorder_timer);
  
  	/* prepare reordering buffer */
  	tid_agg_rx->reorder_buf =
  		kcalloc(buf_size, sizeof(struct sk_buff *), GFP_KERNEL);
  	tid_agg_rx->reorder_time =
  		kcalloc(buf_size, sizeof(unsigned long), GFP_KERNEL);
  	if (!tid_agg_rx->reorder_buf || !tid_agg_rx->reorder_time) {
  		kfree(tid_agg_rx->reorder_buf);
  		kfree(tid_agg_rx->reorder_time);
  		kfree(tid_agg_rx);
  		goto end;
  	}
  
  	ret = drv_ampdu_action(local, sta->sdata, IEEE80211_AMPDU_RX_START,
  			       &sta->sta, tid, &start_seq_num, 0);
  	ht_dbg(sta->sdata, "Rx A-MPDU request on %pM tid %d result %d
  ",
  	       sta->sta.addr, tid, ret);
  	if (ret) {
  		kfree(tid_agg_rx->reorder_buf);
  		kfree(tid_agg_rx->reorder_time);
  		kfree(tid_agg_rx);
  		goto end;
  	}
  
  	/* update data */
  	tid_agg_rx->dialog_token = dialog_token;
  	tid_agg_rx->ssn = start_seq_num;
  	tid_agg_rx->head_seq_num = start_seq_num;
  	tid_agg_rx->buf_size = buf_size;
  	tid_agg_rx->timeout = timeout;
  	tid_agg_rx->stored_mpdu_num = 0;
  	status = WLAN_STATUS_SUCCESS;
  
  	/* activate it for RX */
  	rcu_assign_pointer(sta->ampdu_mlme.tid_rx[tid], tid_agg_rx);
  
  	if (timeout) {
  		mod_timer(&tid_agg_rx->session_timer, TU_TO_EXP_TIME(timeout));
  		tid_agg_rx->last_rx = jiffies;
  	}
  
  end:
  	mutex_unlock(&sta->ampdu_mlme.mtx);
  
  end_no_lock:
  	ieee80211_send_addba_resp(sta->sdata, sta->sta.addr, tid,
  				  dialog_token, status, 1, buf_size, timeout);
  }