/*
   * Copyright (c) 2008-2011 Atheros Communications Inc.
   *
   * Permission to use, copy, modify, and/or distribute this software for any
   * purpose with or without fee is hereby granted, provided that the above
   * copyright notice and this permission notice appear in all copies.
   *
   * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
   * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
   * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
   * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
   * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
   * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
   * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
   */
  
  #include <linux/dma-mapping.h>
  #include "ath9k.h"
  #include "ar9003_mac.h"
  
  #define SKB_CB_ATHBUF(__skb)	(*((struct ath_rxbuf **)__skb->cb))
  
  static inline bool ath9k_check_auto_sleep(struct ath_softc *sc)
  {
  	return sc->ps_enabled &&
  	       (sc->sc_ah->caps.hw_caps & ATH9K_HW_CAP_AUTOSLEEP);
  }
  
  /*
   * Setup and link descriptors.
   *
   * 11N: we can no longer afford to self link the last descriptor.
   * MAC acknowledges BA status as long as it copies frames to host
   * buffer (or rx fifo). This can incorrectly acknowledge packets
   * to a sender if last desc is self-linked.
   */
  static void ath_rx_buf_link(struct ath_softc *sc, struct ath_rxbuf *bf,
  			    bool flush)
  {
  	struct ath_hw *ah = sc->sc_ah;
  	struct ath_common *common = ath9k_hw_common(ah);
  	struct ath_desc *ds;
  	struct sk_buff *skb;
  
  	ds = bf->bf_desc;
  	ds->ds_link = 0; /* link to null */
  	ds->ds_data = bf->bf_buf_addr;
  
  	/* virtual addr of the beginning of the buffer. */
  	skb = bf->bf_mpdu;
  	BUG_ON(skb == NULL);
  	ds->ds_vdata = skb->data;
  
  	/*
  	 * setup rx descriptors. The rx_bufsize here tells the hardware
  	 * how much data it can DMA to us and that we are prepared
  	 * to process
  	 */
  	ath9k_hw_setuprxdesc(ah, ds,
  			     common->rx_bufsize,
  			     0);
  
  	if (sc->rx.rxlink)
  		*sc->rx.rxlink = bf->bf_daddr;
  	else if (!flush)
  		ath9k_hw_putrxbuf(ah, bf->bf_daddr);
  
  	sc->rx.rxlink = &ds->ds_link;
  }
  
  static void ath_rx_buf_relink(struct ath_softc *sc, struct ath_rxbuf *bf,
  			      bool flush)
  {
  	if (sc->rx.buf_hold)
  		ath_rx_buf_link(sc, sc->rx.buf_hold, flush);
  
  	sc->rx.buf_hold = bf;
  }
  
  static void ath_setdefantenna(struct ath_softc *sc, u32 antenna)
  {
  	/* XXX block beacon interrupts */
  	ath9k_hw_setantenna(sc->sc_ah, antenna);
  	sc->rx.defant = antenna;
  	sc->rx.rxotherant = 0;
  }
  
  static void ath_opmode_init(struct ath_softc *sc)
  {
  	struct ath_hw *ah = sc->sc_ah;
  	struct ath_common *common = ath9k_hw_common(ah);
  
  	u32 rfilt, mfilt[2];
  
  	/* configure rx filter */
  	rfilt = ath_calcrxfilter(sc);
  	ath9k_hw_setrxfilter(ah, rfilt);
  
  	/* configure bssid mask */
  	ath_hw_setbssidmask(common);
  
  	/* configure operational mode */
  	ath9k_hw_setopmode(ah);
  
  	/* calculate and install multicast filter */
  	mfilt[0] = mfilt[1] = ~0;
  	ath9k_hw_setmcastfilter(ah, mfilt[0], mfilt[1]);
  }
  
  static bool ath_rx_edma_buf_link(struct ath_softc *sc,
  				 enum ath9k_rx_qtype qtype)
  {
  	struct ath_hw *ah = sc->sc_ah;
  	struct ath_rx_edma *rx_edma;
  	struct sk_buff *skb;
  	struct ath_rxbuf *bf;
  
  	rx_edma = &sc->rx.rx_edma[qtype];
  	if (skb_queue_len(&rx_edma->rx_fifo) >= rx_edma->rx_fifo_hwsize)
  		return false;
  
  	bf = list_first_entry(&sc->rx.rxbuf, struct ath_rxbuf, list);
  	list_del_init(&bf->list);
  
  	skb = bf->bf_mpdu;
  
  	memset(skb->data, 0, ah->caps.rx_status_len);
  	dma_sync_single_for_device(sc->dev, bf->bf_buf_addr,
  				ah->caps.rx_status_len, DMA_TO_DEVICE);
  
  	SKB_CB_ATHBUF(skb) = bf;
  	ath9k_hw_addrxbuf_edma(ah, bf->bf_buf_addr, qtype);
  	__skb_queue_tail(&rx_edma->rx_fifo, skb);
  
  	return true;
  }
  
  static void ath_rx_addbuffer_edma(struct ath_softc *sc,
  				  enum ath9k_rx_qtype qtype)
  {
  	struct ath_common *common = ath9k_hw_common(sc->sc_ah);
  	struct ath_rxbuf *bf, *tbf;
  
  	if (list_empty(&sc->rx.rxbuf)) {
  		ath_dbg(common, QUEUE, "No free rx buf available
  ");
  		return;
  	}
  
  	list_for_each_entry_safe(bf, tbf, &sc->rx.rxbuf, list)
  		if (!ath_rx_edma_buf_link(sc, qtype))
  			break;
  
  }
  
  static void ath_rx_remove_buffer(struct ath_softc *sc,
  				 enum ath9k_rx_qtype qtype)
  {
  	struct ath_rxbuf *bf;
  	struct ath_rx_edma *rx_edma;
  	struct sk_buff *skb;
  
  	rx_edma = &sc->rx.rx_edma[qtype];
  
  	while ((skb = __skb_dequeue(&rx_edma->rx_fifo)) != NULL) {
  		bf = SKB_CB_ATHBUF(skb);
  		BUG_ON(!bf);
  		list_add_tail(&bf->list, &sc->rx.rxbuf);
  	}
  }
  
  static void ath_rx_edma_cleanup(struct ath_softc *sc)
  {
  	struct ath_hw *ah = sc->sc_ah;
  	struct ath_common *common = ath9k_hw_common(ah);
  	struct ath_rxbuf *bf;
  
  	ath_rx_remove_buffer(sc, ATH9K_RX_QUEUE_LP);
  	ath_rx_remove_buffer(sc, ATH9K_RX_QUEUE_HP);
  
  	list_for_each_entry(bf, &sc->rx.rxbuf, list) {
  		if (bf->bf_mpdu) {
  			dma_unmap_single(sc->dev, bf->bf_buf_addr,
  					common->rx_bufsize,
  					DMA_BIDIRECTIONAL);
  			dev_kfree_skb_any(bf->bf_mpdu);
  			bf->bf_buf_addr = 0;
  			bf->bf_mpdu = NULL;
  		}
  	}
  }
  
  static void ath_rx_edma_init_queue(struct ath_rx_edma *rx_edma, int size)
  {
  	__skb_queue_head_init(&rx_edma->rx_fifo);
  	rx_edma->rx_fifo_hwsize = size;
  }
  
  static int ath_rx_edma_init(struct ath_softc *sc, int nbufs)
  {
  	struct ath_common *common = ath9k_hw_common(sc->sc_ah);
  	struct ath_hw *ah = sc->sc_ah;
  	struct sk_buff *skb;
  	struct ath_rxbuf *bf;
  	int error = 0, i;
  	u32 size;
  
  	ath9k_hw_set_rx_bufsize(ah, common->rx_bufsize -
  				    ah->caps.rx_status_len);
  
  	ath_rx_edma_init_queue(&sc->rx.rx_edma[ATH9K_RX_QUEUE_LP],
  			       ah->caps.rx_lp_qdepth);
  	ath_rx_edma_init_queue(&sc->rx.rx_edma[ATH9K_RX_QUEUE_HP],
  			       ah->caps.rx_hp_qdepth);
  
  	size = sizeof(struct ath_rxbuf) * nbufs;
  	bf = devm_kzalloc(sc->dev, size, GFP_KERNEL);
  	if (!bf)
  		return -ENOMEM;
  
  	INIT_LIST_HEAD(&sc->rx.rxbuf);
  
  	for (i = 0; i < nbufs; i++, bf++) {
  		skb = ath_rxbuf_alloc(common, common->rx_bufsize, GFP_KERNEL);
  		if (!skb) {
  			error = -ENOMEM;
  			goto rx_init_fail;
  		}
  
  		memset(skb->data, 0, common->rx_bufsize);
  		bf->bf_mpdu = skb;
  
  		bf->bf_buf_addr = dma_map_single(sc->dev, skb->data,
  						 common->rx_bufsize,
  						 DMA_BIDIRECTIONAL);
  		if (unlikely(dma_mapping_error(sc->dev,
  						bf->bf_buf_addr))) {
  				dev_kfree_skb_any(skb);
  				bf->bf_mpdu = NULL;
  				bf->bf_buf_addr = 0;
  				ath_err(common,
  					"dma_mapping_error() on RX init
  ");
  				error = -ENOMEM;
  				goto rx_init_fail;
  		}
  
  		list_add_tail(&bf->list, &sc->rx.rxbuf);
  	}
  
  	return 0;
  
  rx_init_fail:
  	ath_rx_edma_cleanup(sc);
  	return error;
  }
  
  static void ath_edma_start_recv(struct ath_softc *sc)
  {
  	ath9k_hw_rxena(sc->sc_ah);
  	ath_rx_addbuffer_edma(sc, ATH9K_RX_QUEUE_HP);
  	ath_rx_addbuffer_edma(sc, ATH9K_RX_QUEUE_LP);
  	ath_opmode_init(sc);
  	ath9k_hw_startpcureceive(sc->sc_ah, sc->cur_chan->offchannel);
  }
  
  static void ath_edma_stop_recv(struct ath_softc *sc)
  {
  	ath_rx_remove_buffer(sc, ATH9K_RX_QUEUE_HP);
  	ath_rx_remove_buffer(sc, ATH9K_RX_QUEUE_LP);
  }
  
  int ath_rx_init(struct ath_softc *sc, int nbufs)
  {
  	struct ath_common *common = ath9k_hw_common(sc->sc_ah);
  	struct sk_buff *skb;
  	struct ath_rxbuf *bf;
  	int error = 0;
  
  	spin_lock_init(&sc->sc_pcu_lock);
  
  	common->rx_bufsize = IEEE80211_MAX_MPDU_LEN / 2 +
  			     sc->sc_ah->caps.rx_status_len;
  
  	if (sc->sc_ah->caps.hw_caps & ATH9K_HW_CAP_EDMA)
  		return ath_rx_edma_init(sc, nbufs);
  
  	ath_dbg(common, CONFIG, "cachelsz %u rxbufsize %u
  ",
  		common->cachelsz, common->rx_bufsize);
  
  	/* Initialize rx descriptors */
  
  	error = ath_descdma_setup(sc, &sc->rx.rxdma, &sc->rx.rxbuf,
  				  "rx", nbufs, 1, 0);
  	if (error != 0) {
  		ath_err(common,
  			"failed to allocate rx descriptors: %d
  ",
  			error);
  		goto err;
  	}
  
  	list_for_each_entry(bf, &sc->rx.rxbuf, list) {
  		skb = ath_rxbuf_alloc(common, common->rx_bufsize,
  				      GFP_KERNEL);
  		if (skb == NULL) {
  			error = -ENOMEM;
  			goto err;
  		}
  
  		bf->bf_mpdu = skb;
  		bf->bf_buf_addr = dma_map_single(sc->dev, skb->data,
  						 common->rx_bufsize,
  						 DMA_FROM_DEVICE);
  		if (unlikely(dma_mapping_error(sc->dev,
  					       bf->bf_buf_addr))) {
  			dev_kfree_skb_any(skb);
  			bf->bf_mpdu = NULL;
  			bf->bf_buf_addr = 0;
  			ath_err(common,
  				"dma_mapping_error() on RX init
  ");
  			error = -ENOMEM;
  			goto err;
  		}
  	}
  	sc->rx.rxlink = NULL;
  err:
  	if (error)
  		ath_rx_cleanup(sc);
  
  	return error;
  }
  
  void ath_rx_cleanup(struct ath_softc *sc)
  {
  	struct ath_hw *ah = sc->sc_ah;
  	struct ath_common *common = ath9k_hw_common(ah);
  	struct sk_buff *skb;
  	struct ath_rxbuf *bf;
  
  	if (sc->sc_ah->caps.hw_caps & ATH9K_HW_CAP_EDMA) {
  		ath_rx_edma_cleanup(sc);
  		return;
  	}
  
  	list_for_each_entry(bf, &sc->rx.rxbuf, list) {
  		skb = bf->bf_mpdu;
  		if (skb) {
  			dma_unmap_single(sc->dev, bf->bf_buf_addr,
  					 common->rx_bufsize,
  					 DMA_FROM_DEVICE);
  			dev_kfree_skb(skb);
  			bf->bf_buf_addr = 0;
  			bf->bf_mpdu = NULL;
  		}
  	}
  }
  
  /*
   * Calculate the receive filter according to the
   * operating mode and state:
   *
   * o always accept unicast, broadcast, and multicast traffic
   * o maintain current state of phy error reception (the hal
   *   may enable phy error frames for noise immunity work)
   * o probe request frames are accepted only when operating in
   *   hostap, adhoc, or monitor modes
   * o enable promiscuous mode according to the interface state
   * o accept beacons:
   *   - when operating in adhoc mode so the 802.11 layer creates
   *     node table entries for peers,
   *   - when operating in station mode for collecting rssi data when
   *     the station is otherwise quiet, or
   *   - when operating as a repeater so we see repeater-sta beacons
   *   - when scanning
   */
  
  u32 ath_calcrxfilter(struct ath_softc *sc)
  {
  	struct ath_common *common = ath9k_hw_common(sc->sc_ah);
  	u32 rfilt;
  
  	if (config_enabled(CONFIG_ATH9K_TX99))
  		return 0;
  
  	rfilt = ATH9K_RX_FILTER_UCAST | ATH9K_RX_FILTER_BCAST
  		| ATH9K_RX_FILTER_MCAST;
  
  	/* if operating on a DFS channel, enable radar pulse detection */
  	if (sc->hw->conf.radar_enabled)
  		rfilt |= ATH9K_RX_FILTER_PHYRADAR | ATH9K_RX_FILTER_PHYERR;
  
  	spin_lock_bh(&sc->chan_lock);
  
  	if (sc->cur_chan->rxfilter & FIF_PROBE_REQ)
  		rfilt |= ATH9K_RX_FILTER_PROBEREQ;
  
  	if (sc->sc_ah->is_monitoring)
  		rfilt |= ATH9K_RX_FILTER_PROM;
  
  	if ((sc->cur_chan->rxfilter & FIF_CONTROL) ||
  	    sc->sc_ah->dynack.enabled)
  		rfilt |= ATH9K_RX_FILTER_CONTROL;
  
  	if ((sc->sc_ah->opmode == NL80211_IFTYPE_STATION) &&
  	    (sc->cur_chan->nvifs <= 1) &&
  	    !(sc->cur_chan->rxfilter & FIF_BCN_PRBRESP_PROMISC))
  		rfilt |= ATH9K_RX_FILTER_MYBEACON;
  	else if (sc->sc_ah->opmode != NL80211_IFTYPE_OCB)
  		rfilt |= ATH9K_RX_FILTER_BEACON;
  
  	if ((sc->sc_ah->opmode == NL80211_IFTYPE_AP) ||
  	    (sc->cur_chan->rxfilter & FIF_PSPOLL))
  		rfilt |= ATH9K_RX_FILTER_PSPOLL;
  
  	if (sc->cur_chandef.width != NL80211_CHAN_WIDTH_20_NOHT)
  		rfilt |= ATH9K_RX_FILTER_COMP_BAR;
  
  	if (sc->cur_chan->nvifs > 1 || (sc->cur_chan->rxfilter & FIF_OTHER_BSS)) {
  		/* This is needed for older chips */
  		if (sc->sc_ah->hw_version.macVersion <= AR_SREV_VERSION_9160)
  			rfilt |= ATH9K_RX_FILTER_PROM;
  		rfilt |= ATH9K_RX_FILTER_MCAST_BCAST_ALL;
  	}
  
  	if (AR_SREV_9550(sc->sc_ah) || AR_SREV_9531(sc->sc_ah) ||
  	    AR_SREV_9561(sc->sc_ah))
  		rfilt |= ATH9K_RX_FILTER_4ADDRESS;
  
  	if (ath9k_is_chanctx_enabled() &&
  	    test_bit(ATH_OP_SCANNING, &common->op_flags))
  		rfilt |= ATH9K_RX_FILTER_BEACON;
  
  	spin_unlock_bh(&sc->chan_lock);
  
  	return rfilt;
  
  }
  
  void ath_startrecv(struct ath_softc *sc)
  {
  	struct ath_hw *ah = sc->sc_ah;
  	struct ath_rxbuf *bf, *tbf;
  
  	if (ah->caps.hw_caps & ATH9K_HW_CAP_EDMA) {
  		ath_edma_start_recv(sc);
  		return;
  	}
  
  	if (list_empty(&sc->rx.rxbuf))
  		goto start_recv;
  
  	sc->rx.buf_hold = NULL;
  	sc->rx.rxlink = NULL;
  	list_for_each_entry_safe(bf, tbf, &sc->rx.rxbuf, list) {
  		ath_rx_buf_link(sc, bf, false);
  	}
  
  	/* We could have deleted elements so the list may be empty now */
  	if (list_empty(&sc->rx.rxbuf))
  		goto start_recv;
  
  	bf = list_first_entry(&sc->rx.rxbuf, struct ath_rxbuf, list);
  	ath9k_hw_putrxbuf(ah, bf->bf_daddr);
  	ath9k_hw_rxena(ah);
  
  start_recv:
  	ath_opmode_init(sc);
  	ath9k_hw_startpcureceive(ah, sc->cur_chan->offchannel);
  }
  
  static void ath_flushrecv(struct ath_softc *sc)
  {
  	if (sc->sc_ah->caps.hw_caps & ATH9K_HW_CAP_EDMA)
  		ath_rx_tasklet(sc, 1, true);
  	ath_rx_tasklet(sc, 1, false);
  }
  
  bool ath_stoprecv(struct ath_softc *sc)
  {
  	struct ath_hw *ah = sc->sc_ah;
  	bool stopped, reset = false;
  
  	ath9k_hw_abortpcurecv(ah);
  	ath9k_hw_setrxfilter(ah, 0);
  	stopped = ath9k_hw_stopdmarecv(ah, &reset);
  
  	ath_flushrecv(sc);
  
  	if (sc->sc_ah->caps.hw_caps & ATH9K_HW_CAP_EDMA)
  		ath_edma_stop_recv(sc);
  	else
  		sc->rx.rxlink = NULL;
  
  	if (!(ah->ah_flags & AH_UNPLUGGED) &&
  	    unlikely(!stopped)) {
  		ath_dbg(ath9k_hw_common(sc->sc_ah), RESET,
  			"Failed to stop Rx DMA
  ");
  		RESET_STAT_INC(sc, RESET_RX_DMA_ERROR);
  	}
  	return stopped && !reset;
  }
  
  static bool ath_beacon_dtim_pending_cab(struct sk_buff *skb)
  {
  	/* Check whether the Beacon frame has DTIM indicating buffered bc/mc */
  	struct ieee80211_mgmt *mgmt;
  	u8 *pos, *end, id, elen;
  	struct ieee80211_tim_ie *tim;
  
  	mgmt = (struct ieee80211_mgmt *)skb->data;
  	pos = mgmt->u.beacon.variable;
  	end = skb->data + skb->len;
  
  	while (pos + 2 < end) {
  		id = *pos++;
  		elen = *pos++;
  		if (pos + elen > end)
  			break;
  
  		if (id == WLAN_EID_TIM) {
  			if (elen < sizeof(*tim))
  				break;
  			tim = (struct ieee80211_tim_ie *) pos;
  			if (tim->dtim_count != 0)
  				break;
  			return tim->bitmap_ctrl & 0x01;
  		}
  
  		pos += elen;
  	}
  
  	return false;
  }
  
  static void ath_rx_ps_beacon(struct ath_softc *sc, struct sk_buff *skb)
  {
  	struct ath_common *common = ath9k_hw_common(sc->sc_ah);
  	bool skip_beacon = false;
  
  	if (skb->len < 24 + 8 + 2 + 2)
  		return;
  
  	sc->ps_flags &= ~PS_WAIT_FOR_BEACON;
  
  	if (sc->ps_flags & PS_BEACON_SYNC) {
  		sc->ps_flags &= ~PS_BEACON_SYNC;
  		ath_dbg(common, PS,
  			"Reconfigure beacon timers based on synchronized timestamp
  ");
  
  #ifdef CONFIG_ATH9K_CHANNEL_CONTEXT
  		if (ath9k_is_chanctx_enabled()) {
  			if (sc->cur_chan == &sc->offchannel.chan)
  				skip_beacon = true;
  		}
  #endif
  
  		if (!skip_beacon &&
  		    !(WARN_ON_ONCE(sc->cur_chan->beacon.beacon_interval == 0)))
  			ath9k_set_beacon(sc);
  
  		ath9k_p2p_beacon_sync(sc);
  	}
  
  	if (ath_beacon_dtim_pending_cab(skb)) {
  		/*
  		 * Remain awake waiting for buffered broadcast/multicast
  		 * frames. If the last broadcast/multicast frame is not
  		 * received properly, the next beacon frame will work as
  		 * a backup trigger for returning into NETWORK SLEEP state,
  		 * so we are waiting for it as well.
  		 */
  		ath_dbg(common, PS,
  			"Received DTIM beacon indicating buffered broadcast/multicast frame(s)
  ");
  		sc->ps_flags |= PS_WAIT_FOR_CAB | PS_WAIT_FOR_BEACON;
  		return;
  	}
  
  	if (sc->ps_flags & PS_WAIT_FOR_CAB) {
  		/*
  		 * This can happen if a broadcast frame is dropped or the AP
  		 * fails to send a frame indicating that all CAB frames have
  		 * been delivered.
  		 */
  		sc->ps_flags &= ~PS_WAIT_FOR_CAB;
  		ath_dbg(common, PS, "PS wait for CAB frames timed out
  ");
  	}
  }
  
  static void ath_rx_ps(struct ath_softc *sc, struct sk_buff *skb, bool mybeacon)
  {
  	struct ieee80211_hdr *hdr;
  	struct ath_common *common = ath9k_hw_common(sc->sc_ah);
  
  	hdr = (struct ieee80211_hdr *)skb->data;
  
  	/* Process Beacon and CAB receive in PS state */
  	if (((sc->ps_flags & PS_WAIT_FOR_BEACON) || ath9k_check_auto_sleep(sc))
  	    && mybeacon) {
  		ath_rx_ps_beacon(sc, skb);
  	} else if ((sc->ps_flags & PS_WAIT_FOR_CAB) &&
  		   (ieee80211_is_data(hdr->frame_control) ||
  		    ieee80211_is_action(hdr->frame_control)) &&
  		   is_multicast_ether_addr(hdr->addr1) &&
  		   !ieee80211_has_moredata(hdr->frame_control)) {
  		/*
  		 * No more broadcast/multicast frames to be received at this
  		 * point.
  		 */
  		sc->ps_flags &= ~(PS_WAIT_FOR_CAB | PS_WAIT_FOR_BEACON);
  		ath_dbg(common, PS,
  			"All PS CAB frames received, back to sleep
  ");
  	} else if ((sc->ps_flags & PS_WAIT_FOR_PSPOLL_DATA) &&
  		   !is_multicast_ether_addr(hdr->addr1) &&
  		   !ieee80211_has_morefrags(hdr->frame_control)) {
  		sc->ps_flags &= ~PS_WAIT_FOR_PSPOLL_DATA;
  		ath_dbg(common, PS,
  			"Going back to sleep after having received PS-Poll data (0x%lx)
  ",
  			sc->ps_flags & (PS_WAIT_FOR_BEACON |
  					PS_WAIT_FOR_CAB |
  					PS_WAIT_FOR_PSPOLL_DATA |
  					PS_WAIT_FOR_TX_ACK));
  	}
  }
  
  static bool ath_edma_get_buffers(struct ath_softc *sc,
  				 enum ath9k_rx_qtype qtype,
  				 struct ath_rx_status *rs,
  				 struct ath_rxbuf **dest)
  {
  	struct ath_rx_edma *rx_edma = &sc->rx.rx_edma[qtype];
  	struct ath_hw *ah = sc->sc_ah;
  	struct ath_common *common = ath9k_hw_common(ah);
  	struct sk_buff *skb;
  	struct ath_rxbuf *bf;
  	int ret;
  
  	skb = skb_peek(&rx_edma->rx_fifo);
  	if (!skb)
  		return false;
  
  	bf = SKB_CB_ATHBUF(skb);
  	BUG_ON(!bf);
  
  	dma_sync_single_for_cpu(sc->dev, bf->bf_buf_addr,
  				common->rx_bufsize, DMA_FROM_DEVICE);
  
  	ret = ath9k_hw_process_rxdesc_edma(ah, rs, skb->data);
  	if (ret == -EINPROGRESS) {
  		/*let device gain the buffer again*/
  		dma_sync_single_for_device(sc->dev, bf->bf_buf_addr,
  				common->rx_bufsize, DMA_FROM_DEVICE);
  		return false;
  	}
  
  	__skb_unlink(skb, &rx_edma->rx_fifo);
  	if (ret == -EINVAL) {
  		/* corrupt descriptor, skip this one and the following one */
  		list_add_tail(&bf->list, &sc->rx.rxbuf);
  		ath_rx_edma_buf_link(sc, qtype);
  
  		skb = skb_peek(&rx_edma->rx_fifo);
  		if (skb) {
  			bf = SKB_CB_ATHBUF(skb);
  			BUG_ON(!bf);
  
  			__skb_unlink(skb, &rx_edma->rx_fifo);
  			list_add_tail(&bf->list, &sc->rx.rxbuf);
  			ath_rx_edma_buf_link(sc, qtype);
  		}
  
  		bf = NULL;
  	}
  
  	*dest = bf;
  	return true;
  }
  
  static struct ath_rxbuf *ath_edma_get_next_rx_buf(struct ath_softc *sc,
  						struct ath_rx_status *rs,
  						enum ath9k_rx_qtype qtype)
  {
  	struct ath_rxbuf *bf = NULL;
  
  	while (ath_edma_get_buffers(sc, qtype, rs, &bf)) {
  		if (!bf)
  			continue;
  
  		return bf;
  	}
  	return NULL;
  }
  
  static struct ath_rxbuf *ath_get_next_rx_buf(struct ath_softc *sc,
  					   struct ath_rx_status *rs)
  {
  	struct ath_hw *ah = sc->sc_ah;
  	struct ath_common *common = ath9k_hw_common(ah);
  	struct ath_desc *ds;
  	struct ath_rxbuf *bf;
  	int ret;
  
  	if (list_empty(&sc->rx.rxbuf)) {
  		sc->rx.rxlink = NULL;
  		return NULL;
  	}
  
  	bf = list_first_entry(&sc->rx.rxbuf, struct ath_rxbuf, list);
  	if (bf == sc->rx.buf_hold)
  		return NULL;
  
  	ds = bf->bf_desc;
  
  	/*
  	 * Must provide the virtual address of the current
  	 * descriptor, the physical address, and the virtual
  	 * address of the next descriptor in the h/w chain.
  	 * This allows the HAL to look ahead to see if the
  	 * hardware is done with a descriptor by checking the
  	 * done bit in the following descriptor and the address
  	 * of the current descriptor the DMA engine is working
  	 * on.  All this is necessary because of our use of
  	 * a self-linked list to avoid rx overruns.
  	 */
  	ret = ath9k_hw_rxprocdesc(ah, ds, rs);
  	if (ret == -EINPROGRESS) {
  		struct ath_rx_status trs;
  		struct ath_rxbuf *tbf;
  		struct ath_desc *tds;
  
  		memset(&trs, 0, sizeof(trs));
  		if (list_is_last(&bf->list, &sc->rx.rxbuf)) {
  			sc->rx.rxlink = NULL;
  			return NULL;
  		}
  
  		tbf = list_entry(bf->list.next, struct ath_rxbuf, list);
  
  		/*
  		 * On some hardware the descriptor status words could
  		 * get corrupted, including the done bit. Because of
  		 * this, check if the next descriptor's done bit is
  		 * set or not.
  		 *
  		 * If the next descriptor's done bit is set, the current
  		 * descriptor has been corrupted. Force s/w to discard
  		 * this descriptor and continue...
  		 */
  
  		tds = tbf->bf_desc;
  		ret = ath9k_hw_rxprocdesc(ah, tds, &trs);
  		if (ret == -EINPROGRESS)
  			return NULL;
  
  		/*
  		 * Re-check previous descriptor, in case it has been filled
  		 * in the mean time.
  		 */
  		ret = ath9k_hw_rxprocdesc(ah, ds, rs);
  		if (ret == -EINPROGRESS) {
  			/*
  			 * mark descriptor as zero-length and set the 'more'
  			 * flag to ensure that both buffers get discarded
  			 */
  			rs->rs_datalen = 0;
  			rs->rs_more = true;
  		}
  	}
  
  	list_del(&bf->list);
  	if (!bf->bf_mpdu)
  		return bf;
  
  	/*
  	 * Synchronize the DMA transfer with CPU before
  	 * 1. accessing the frame
  	 * 2. requeueing the same buffer to h/w
  	 */
  	dma_sync_single_for_cpu(sc->dev, bf->bf_buf_addr,
  			common->rx_bufsize,
  			DMA_FROM_DEVICE);
  
  	return bf;
  }
  
  static void ath9k_process_tsf(struct ath_rx_status *rs,
  			      struct ieee80211_rx_status *rxs,
  			      u64 tsf)
  {
  	u32 tsf_lower = tsf & 0xffffffff;
  
  	rxs->mactime = (tsf & ~0xffffffffULL) | rs->rs_tstamp;
  	if (rs->rs_tstamp > tsf_lower &&
  	    unlikely(rs->rs_tstamp - tsf_lower > 0x10000000))
  		rxs->mactime -= 0x100000000ULL;
  
  	if (rs->rs_tstamp < tsf_lower &&
  	    unlikely(tsf_lower - rs->rs_tstamp > 0x10000000))
  		rxs->mactime += 0x100000000ULL;
  }
  
  /*
   * For Decrypt or Demic errors, we only mark packet status here and always push
   * up the frame up to let mac80211 handle the actual error case, be it no
   * decryption key or real decryption error. This let us keep statistics there.
   */
  static int ath9k_rx_skb_preprocess(struct ath_softc *sc,
  				   struct sk_buff *skb,
  				   struct ath_rx_status *rx_stats,
  				   struct ieee80211_rx_status *rx_status,
  				   bool *decrypt_error, u64 tsf)
  {
  	struct ieee80211_hw *hw = sc->hw;
  	struct ath_hw *ah = sc->sc_ah;
  	struct ath_common *common = ath9k_hw_common(ah);
  	struct ieee80211_hdr *hdr;
  	bool discard_current = sc->rx.discard_next;
  
  	/*
  	 * Discard corrupt descriptors which are marked in
  	 * ath_get_next_rx_buf().
  	 */
  	if (discard_current)
  		goto corrupt;
  
  	sc->rx.discard_next = false;
  
  	/*
  	 * Discard zero-length packets.
  	 */
  	if (!rx_stats->rs_datalen) {
  		RX_STAT_INC(rx_len_err);
  		goto corrupt;
  	}
  
  	/*
  	 * rs_status follows rs_datalen so if rs_datalen is too large
  	 * we can take a hint that hardware corrupted it, so ignore
  	 * those frames.
  	 */
  	if (rx_stats->rs_datalen > (common->rx_bufsize - ah->caps.rx_status_len)) {
  		RX_STAT_INC(rx_len_err);
  		goto corrupt;
  	}
  
  	/* Only use status info from the last fragment */
  	if (rx_stats->rs_more)
  		return 0;
  
  	/*
  	 * Return immediately if the RX descriptor has been marked
  	 * as corrupt based on the various error bits.
  	 *
  	 * This is different from the other corrupt descriptor
  	 * condition handled above.
  	 */
  	if (rx_stats->rs_status & ATH9K_RXERR_CORRUPT_DESC)
  		goto corrupt;
  
  	hdr = (struct ieee80211_hdr *) (skb->data + ah->caps.rx_status_len);
  
  	ath9k_process_tsf(rx_stats, rx_status, tsf);
  	ath_debug_stat_rx(sc, rx_stats);
  
  	/*
  	 * Process PHY errors and return so that the packet
  	 * can be dropped.
  	 */
  	if (rx_stats->rs_status & ATH9K_RXERR_PHY) {
  		ath9k_dfs_process_phyerr(sc, hdr, rx_stats, rx_status->mactime);
  		if (ath_cmn_process_fft(&sc->spec_priv, hdr, rx_stats, rx_status->mactime))
  			RX_STAT_INC(rx_spectral);
  
  		return -EINVAL;
  	}
  
  	/*
  	 * everything but the rate is checked here, the rate check is done
  	 * separately to avoid doing two lookups for a rate for each frame.
  	 */
  	spin_lock_bh(&sc->chan_lock);
  	if (!ath9k_cmn_rx_accept(common, hdr, rx_status, rx_stats, decrypt_error,
  				 sc->cur_chan->rxfilter)) {
  		spin_unlock_bh(&sc->chan_lock);
  		return -EINVAL;
  	}
  	spin_unlock_bh(&sc->chan_lock);
  
  	if (ath_is_mybeacon(common, hdr)) {
  		RX_STAT_INC(rx_beacons);
  		rx_stats->is_mybeacon = true;
  	}
  
  	/*
  	 * This shouldn't happen, but have a safety check anyway.
  	 */
  	if (WARN_ON(!ah->curchan))
  		return -EINVAL;
  
  	if (ath9k_cmn_process_rate(common, hw, rx_stats, rx_status)) {
  		/*
  		 * No valid hardware bitrate found -- we should not get here
  		 * because hardware has already validated this frame as OK.
  		 */
  		ath_dbg(common, ANY, "unsupported hw bitrate detected 0x%02x using 1 Mbit
  ",
  			rx_stats->rs_rate);
  		RX_STAT_INC(rx_rate_err);
  		return -EINVAL;
  	}
  
  	if (ath9k_is_chanctx_enabled()) {
  		if (rx_stats->is_mybeacon)
  			ath_chanctx_beacon_recv_ev(sc,
  					   ATH_CHANCTX_EVENT_BEACON_RECEIVED);
  	}
  
  	ath9k_cmn_process_rssi(common, hw, rx_stats, rx_status);
  
  	rx_status->band = ah->curchan->chan->band;
  	rx_status->freq = ah->curchan->chan->center_freq;
  	rx_status->antenna = rx_stats->rs_antenna;
  	rx_status->flag |= RX_FLAG_MACTIME_END;
  
  #ifdef CONFIG_ATH9K_BTCOEX_SUPPORT
  	if (ieee80211_is_data_present(hdr->frame_control) &&
  	    !ieee80211_is_qos_nullfunc(hdr->frame_control))
  		sc->rx.num_pkts++;
  #endif
  
  	return 0;
  
  corrupt:
  	sc->rx.discard_next = rx_stats->rs_more;
  	return -EINVAL;
  }
  
  /*
   * Run the LNA combining algorithm only in these cases:
   *
   * Standalone WLAN cards with both LNA/Antenna diversity
   * enabled in the EEPROM.
   *
   * WLAN+BT cards which are in the supported card list
   * in ath_pci_id_table and the user has loaded the
   * driver with "bt_ant_diversity" set to true.
   */
  static void ath9k_antenna_check(struct ath_softc *sc,
  				struct ath_rx_status *rs)
  {
  	struct ath_hw *ah = sc->sc_ah;
  	struct ath9k_hw_capabilities *pCap = &ah->caps;
  	struct ath_common *common = ath9k_hw_common(ah);
  
  	if (!(ah->caps.hw_caps & ATH9K_HW_CAP_ANT_DIV_COMB))
  		return;
  
  	/*
  	 * Change the default rx antenna if rx diversity
  	 * chooses the other antenna 3 times in a row.
  	 */
  	if (sc->rx.defant != rs->rs_antenna) {
  		if (++sc->rx.rxotherant >= 3)
  			ath_setdefantenna(sc, rs->rs_antenna);
  	} else {
  		sc->rx.rxotherant = 0;
  	}
  
  	if (pCap->hw_caps & ATH9K_HW_CAP_BT_ANT_DIV) {
  		if (common->bt_ant_diversity)
  			ath_ant_comb_scan(sc, rs);
  	} else {
  		ath_ant_comb_scan(sc, rs);
  	}
  }
  
  static void ath9k_apply_ampdu_details(struct ath_softc *sc,
  	struct ath_rx_status *rs, struct ieee80211_rx_status *rxs)
  {
  	if (rs->rs_isaggr) {
  		rxs->flag |= RX_FLAG_AMPDU_DETAILS | RX_FLAG_AMPDU_LAST_KNOWN;
  
  		rxs->ampdu_reference = sc->rx.ampdu_ref;
  
  		if (!rs->rs_moreaggr) {
  			rxs->flag |= RX_FLAG_AMPDU_IS_LAST;
  			sc->rx.ampdu_ref++;
  		}
  
  		if (rs->rs_flags & ATH9K_RX_DELIM_CRC_PRE)
  			rxs->flag |= RX_FLAG_AMPDU_DELIM_CRC_ERROR;
  	}
  }
  
  int ath_rx_tasklet(struct ath_softc *sc, int flush, bool hp)
  {
  	struct ath_rxbuf *bf;
  	struct sk_buff *skb = NULL, *requeue_skb, *hdr_skb;
  	struct ieee80211_rx_status *rxs;
  	struct ath_hw *ah = sc->sc_ah;
  	struct ath_common *common = ath9k_hw_common(ah);
  	struct ieee80211_hw *hw = sc->hw;
  	int retval;
  	struct ath_rx_status rs;
  	enum ath9k_rx_qtype qtype;
  	bool edma = !!(ah->caps.hw_caps & ATH9K_HW_CAP_EDMA);
  	int dma_type;
  	u64 tsf = 0;
  	unsigned long flags;
  	dma_addr_t new_buf_addr;
  	unsigned int budget = 512;
  	struct ieee80211_hdr *hdr;
  
  	if (edma)
  		dma_type = DMA_BIDIRECTIONAL;
  	else
  		dma_type = DMA_FROM_DEVICE;
  
  	qtype = hp ? ATH9K_RX_QUEUE_HP : ATH9K_RX_QUEUE_LP;
  
  	tsf = ath9k_hw_gettsf64(ah);
  
  	do {
  		bool decrypt_error = false;
  
  		memset(&rs, 0, sizeof(rs));
  		if (edma)
  			bf = ath_edma_get_next_rx_buf(sc, &rs, qtype);
  		else
  			bf = ath_get_next_rx_buf(sc, &rs);
  
  		if (!bf)
  			break;
  
  		skb = bf->bf_mpdu;
  		if (!skb)
  			continue;
  
  		/*
  		 * Take frame header from the first fragment and RX status from
  		 * the last one.
  		 */
  		if (sc->rx.frag)
  			hdr_skb = sc->rx.frag;
  		else
  			hdr_skb = skb;
  
  		rxs = IEEE80211_SKB_RXCB(hdr_skb);
  		memset(rxs, 0, sizeof(struct ieee80211_rx_status));
  
  		retval = ath9k_rx_skb_preprocess(sc, hdr_skb, &rs, rxs,
  						 &decrypt_error, tsf);
  		if (retval)
  			goto requeue_drop_frag;
  
  		/* Ensure we always have an skb to requeue once we are done
  		 * processing the current buffer's skb */
  		requeue_skb = ath_rxbuf_alloc(common, common->rx_bufsize, GFP_ATOMIC);
  
  		/* If there is no memory we ignore the current RX'd frame,
  		 * tell hardware it can give us a new frame using the old
  		 * skb and put it at the tail of the sc->rx.rxbuf list for
  		 * processing. */
  		if (!requeue_skb) {
  			RX_STAT_INC(rx_oom_err);
  			goto requeue_drop_frag;
  		}
  
  		/* We will now give hardware our shiny new allocated skb */
  		new_buf_addr = dma_map_single(sc->dev, requeue_skb->data,
  					      common->rx_bufsize, dma_type);
  		if (unlikely(dma_mapping_error(sc->dev, new_buf_addr))) {
  			dev_kfree_skb_any(requeue_skb);
  			goto requeue_drop_frag;
  		}
  
  		/* Unmap the frame */
  		dma_unmap_single(sc->dev, bf->bf_buf_addr,
  				 common->rx_bufsize, dma_type);
  
  		bf->bf_mpdu = requeue_skb;
  		bf->bf_buf_addr = new_buf_addr;
  
  		skb_put(skb, rs.rs_datalen + ah->caps.rx_status_len);
  		if (ah->caps.rx_status_len)
  			skb_pull(skb, ah->caps.rx_status_len);
  
  		if (!rs.rs_more)
  			ath9k_cmn_rx_skb_postprocess(common, hdr_skb, &rs,
  						     rxs, decrypt_error);
  
  		if (rs.rs_more) {
  			RX_STAT_INC(rx_frags);
  			/*
  			 * rs_more indicates chained descriptors which can be
  			 * used to link buffers together for a sort of
  			 * scatter-gather operation.
  			 */
  			if (sc->rx.frag) {
  				/* too many fragments - cannot handle frame */
  				dev_kfree_skb_any(sc->rx.frag);
  				dev_kfree_skb_any(skb);
  				RX_STAT_INC(rx_too_many_frags_err);
  				skb = NULL;
  			}
  			sc->rx.frag = skb;
  			goto requeue;
  		}
  
  		if (sc->rx.frag) {
  			int space = skb->len - skb_tailroom(hdr_skb);
  
  			if (pskb_expand_head(hdr_skb, 0, space, GFP_ATOMIC) < 0) {
  				dev_kfree_skb(skb);
  				RX_STAT_INC(rx_oom_err);
  				goto requeue_drop_frag;
  			}
  
  			sc->rx.frag = NULL;
  
  			skb_copy_from_linear_data(skb, skb_put(hdr_skb, skb->len),
  						  skb->len);
  			dev_kfree_skb_any(skb);
  			skb = hdr_skb;
  		}
  
  		if (rxs->flag & RX_FLAG_MMIC_STRIPPED)
  			skb_trim(skb, skb->len - 8);
  
  		spin_lock_irqsave(&sc->sc_pm_lock, flags);
  		if ((sc->ps_flags & (PS_WAIT_FOR_BEACON |
  				     PS_WAIT_FOR_CAB |
  				     PS_WAIT_FOR_PSPOLL_DATA)) ||
  		    ath9k_check_auto_sleep(sc))
  			ath_rx_ps(sc, skb, rs.is_mybeacon);
  		spin_unlock_irqrestore(&sc->sc_pm_lock, flags);
  
  		ath9k_antenna_check(sc, &rs);
  		ath9k_apply_ampdu_details(sc, &rs, rxs);
  		ath_debug_rate_stats(sc, &rs, skb);
  
  		hdr = (struct ieee80211_hdr *)skb->data;
  		if (ieee80211_is_ack(hdr->frame_control))
  			ath_dynack_sample_ack_ts(sc->sc_ah, skb, rs.rs_tstamp);
  
  		ieee80211_rx(hw, skb);
  
  requeue_drop_frag:
  		if (sc->rx.frag) {
  			dev_kfree_skb_any(sc->rx.frag);
  			sc->rx.frag = NULL;
  		}
  requeue:
  		list_add_tail(&bf->list, &sc->rx.rxbuf);
  
  		if (!edma) {
  			ath_rx_buf_relink(sc, bf, flush);
  			if (!flush)
  				ath9k_hw_rxena(ah);
  		} else if (!flush) {
  			ath_rx_edma_buf_link(sc, qtype);
  		}
  
  		if (!budget--)
  			break;
  	} while (1);
  
  	if (!(ah->imask & ATH9K_INT_RXEOL)) {
  		ah->imask |= (ATH9K_INT_RXEOL | ATH9K_INT_RXORN);
  		ath9k_hw_set_interrupts(ah);
  	}
  
  	return 0;
  }