drivers/net/wireless/ath9k/recv.c - kernel/msm-4.9 - Gitiles

 /*
  * Copyright (c) 2008 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 "core.h"

 /*
  * 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_buf *bf)
 {
 	struct ath_hal *ah = sc->sc_ah;
 	struct ath_desc *ds;
 	struct sk_buff *skb;

 	ATH_RXBUF_RESET(bf);

 	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;
 	ASSERT(skb != NULL);
 	ds->ds_vdata = skb->data;

 	/* setup rx descriptors. The rx.bufsize here tells the harware
 	 * how much data it can DMA to us and that we are prepared
 	 * to process */
 	ath9k_hw_setuprxdesc(ah, ds,
 			     sc->rx.bufsize,
 			     0);

 	if (sc->rx.rxlink == NULL)
 		ath9k_hw_putrxbuf(ah, bf->bf_daddr);
 	else
 		*sc->rx.rxlink = bf->bf_daddr;

 	sc->rx.rxlink = &ds->ds_link;
 	ath9k_hw_rxena(ah);
 }

 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;
 }

 /*
  *  Extend 15-bit time stamp from rx descriptor to
  *  a full 64-bit TSF using the current h/w TSF.
 */
 static u64 ath_extend_tsf(struct ath_softc *sc, u32 rstamp)
 {
 	u64 tsf;

 	tsf = ath9k_hw_gettsf64(sc->sc_ah);
 	if ((tsf & 0x7fff) < rstamp)
 		tsf -= 0x8000;
 	return (tsf & ~0x7fff) | rstamp;
 }

 static struct sk_buff *ath_rxbuf_alloc(struct ath_softc *sc, u32 len)
 {
 	struct sk_buff *skb;
 	u32 off;

 	/*
 	 * Cache-line-align.  This is important (for the
 	 * 5210 at least) as not doing so causes bogus data
 	 * in rx'd frames.
 	 */

 	/* Note: the kernel can allocate a value greater than
 	 * what we ask it to give us. We really only need 4 KB as that
 	 * is this hardware supports and in fact we need at least 3849
 	 * as that is the MAX AMSDU size this hardware supports.
 	 * Unfortunately this means we may get 8 KB here from the
 	 * kernel... and that is actually what is observed on some
 	 * systems :( */
 	skb = dev_alloc_skb(len + sc->sc_cachelsz - 1);
 	if (skb != NULL) {
 		off = ((unsigned long) skb->data) % sc->sc_cachelsz;
 		if (off != 0)
 			skb_reserve(skb, sc->sc_cachelsz - off);
 	} else {
 		DPRINTF(sc, ATH_DBG_FATAL,
 			"skbuff alloc of size %u failed\n", len);
 		return NULL;
 	}

 	return skb;
 }

 /*
  * 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 ath_rx_prepare(struct sk_buff *skb, struct ath_desc *ds,
 			  struct ieee80211_rx_status *rx_status, bool *decrypt_error,
 			  struct ath_softc *sc)
 {
 	struct ieee80211_hdr *hdr;
 	u8 ratecode;
 	__le16 fc;

 	hdr = (struct ieee80211_hdr *)skb->data;
 	fc = hdr->frame_control;
 	memset(rx_status, 0, sizeof(struct ieee80211_rx_status));

 	if (ds->ds_rxstat.rs_more) {
 		/*
 		 * Frame spans multiple descriptors; this cannot happen yet
 		 * as we don't support jumbograms. If not in monitor mode,
 		 * discard the frame. Enable this if you want to see
 		 * error frames in Monitor mode.
 		 */
 		if (sc->sc_ah->ah_opmode != NL80211_IFTYPE_MONITOR)
 			goto rx_next;
 	} else if (ds->ds_rxstat.rs_status != 0) {
 		if (ds->ds_rxstat.rs_status & ATH9K_RXERR_CRC)
 			rx_status->flag |= RX_FLAG_FAILED_FCS_CRC;
 		if (ds->ds_rxstat.rs_status & ATH9K_RXERR_PHY)
 			goto rx_next;

 		if (ds->ds_rxstat.rs_status & ATH9K_RXERR_DECRYPT) {
 			*decrypt_error = true;
 		} else if (ds->ds_rxstat.rs_status & ATH9K_RXERR_MIC) {
 			if (ieee80211_is_ctl(fc))
 				/*
 				 * Sometimes, we get invalid
 				 * MIC failures on valid control frames.
 				 * Remove these mic errors.
 				 */
 				ds->ds_rxstat.rs_status &= ~ATH9K_RXERR_MIC;
 			else
 				rx_status->flag |= RX_FLAG_MMIC_ERROR;
 		}
 		/*
 		 * Reject error frames with the exception of
 		 * decryption and MIC failures. For monitor mode,
 		 * we also ignore the CRC error.
 		 */
 		if (sc->sc_ah->ah_opmode == NL80211_IFTYPE_MONITOR) {
 			if (ds->ds_rxstat.rs_status &
 			    ~(ATH9K_RXERR_DECRYPT | ATH9K_RXERR_MIC |
 			      ATH9K_RXERR_CRC))
 				goto rx_next;
 		} else {
 			if (ds->ds_rxstat.rs_status &
 			    ~(ATH9K_RXERR_DECRYPT | ATH9K_RXERR_MIC)) {
 				goto rx_next;
 			}
 		}
 	}

 	ratecode = ds->ds_rxstat.rs_rate;

 	if (ratecode & 0x80) {
 		/* HT rate */
 		rx_status->flag |= RX_FLAG_HT;
 		if (ds->ds_rxstat.rs_flags & ATH9K_RX_2040)
 			rx_status->flag |= RX_FLAG_40MHZ;
 		if (ds->ds_rxstat.rs_flags & ATH9K_RX_GI)
 			rx_status->flag |= RX_FLAG_SHORT_GI;
 		rx_status->rate_idx = ratecode & 0x7f;
 	} else {
 		int i = 0, cur_band, n_rates;
 		struct ieee80211_hw *hw = sc->hw;

 		cur_band = hw->conf.channel->band;
 		n_rates = sc->sbands[cur_band].n_bitrates;

 		for (i = 0; i < n_rates; i++) {
 			if (sc->sbands[cur_band].bitrates[i].hw_value ==
 			    ratecode) {
 				rx_status->rate_idx = i;
 				break;
 			}

 			if (sc->sbands[cur_band].bitrates[i].hw_value_short ==
 			    ratecode) {
 				rx_status->rate_idx = i;
 				rx_status->flag |= RX_FLAG_SHORTPRE;
 				break;
 			}
 		}
 	}

 	rx_status->mactime = ath_extend_tsf(sc, ds->ds_rxstat.rs_tstamp);
 	rx_status->band = sc->hw->conf.channel->band;
 	rx_status->freq =  sc->hw->conf.channel->center_freq;
 	rx_status->noise = sc->sc_ani.sc_noise_floor;
 	rx_status->signal = rx_status->noise + ds->ds_rxstat.rs_rssi;
 	rx_status->antenna = ds->ds_rxstat.rs_antenna;

 	/* at 45 you will be able to use MCS 15 reliably. A more elaborate
 	 * scheme can be used here but it requires tables of SNR/throughput for
 	 * each possible mode used. */
 	rx_status->qual =  ds->ds_rxstat.rs_rssi * 100 / 45;

 	/* rssi can be more than 45 though, anything above that
 	 * should be considered at 100% */
 	if (rx_status->qual > 100)
 		rx_status->qual = 100;

 	rx_status->flag |= RX_FLAG_TSFT;

 	return 1;
 rx_next:
 	return 0;
 }

 static void ath_opmode_init(struct ath_softc *sc)
 {
 	struct ath_hal *ah = sc->sc_ah;
 	u32 rfilt, mfilt[2];

 	/* configure rx filter */
 	rfilt = ath_calcrxfilter(sc);
 	ath9k_hw_setrxfilter(ah, rfilt);

 	/* configure bssid mask */
 	if (ah->ah_caps.hw_caps & ATH9K_HW_CAP_BSSIDMASK)
 		ath9k_hw_setbssidmask(ah, sc->sc_bssidmask);

 	/* configure operational mode */
 	ath9k_hw_setopmode(ah);

 	/* Handle any link-level address change. */
 	ath9k_hw_setmac(ah, sc->sc_myaddr);

 	/* calculate and install multicast filter */
 	mfilt[0] = mfilt[1] = ~0;
 	ath9k_hw_setmcastfilter(ah, mfilt[0], mfilt[1]);
 }

 int ath_rx_init(struct ath_softc *sc, int nbufs)
 {
 	struct sk_buff *skb;
 	struct ath_buf *bf;
 	int error = 0;

 	do {
 		spin_lock_init(&sc->rx.rxflushlock);
 		sc->sc_flags &= ~SC_OP_RXFLUSH;
 		spin_lock_init(&sc->rx.rxbuflock);

 		sc->rx.bufsize = roundup(IEEE80211_MAX_MPDU_LEN,
 					   min(sc->sc_cachelsz,
 					       (u16)64));

 		DPRINTF(sc, ATH_DBG_CONFIG, "cachelsz %u rxbufsize %u\n",
 			sc->sc_cachelsz, sc->rx.bufsize);

 		/* Initialize rx descriptors */

 		error = ath_descdma_setup(sc, &sc->rx.rxdma, &sc->rx.rxbuf,
 					  "rx", nbufs, 1);
 		if (error != 0) {
 			DPRINTF(sc, ATH_DBG_FATAL,
 				"failed to allocate rx descriptors: %d\n", error);
 			break;
 		}

 		list_for_each_entry(bf, &sc->rx.rxbuf, list) {
 			skb = ath_rxbuf_alloc(sc, sc->rx.bufsize);
 			if (skb == NULL) {
 				error = -ENOMEM;
 				break;
 			}

 			bf->bf_mpdu = skb;
 			bf->bf_buf_addr = dma_map_single(sc->dev, skb->data,
 							 sc->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;
 				DPRINTF(sc, ATH_DBG_CONFIG,
 					"dma_mapping_error() on RX init\n");
 				error = -ENOMEM;
 				break;
 			}
 			bf->bf_dmacontext = bf->bf_buf_addr;
 		}
 		sc->rx.rxlink = NULL;

 	} while (0);

 	if (error)
 		ath_rx_cleanup(sc);

 	return error;
 }

 void ath_rx_cleanup(struct ath_softc *sc)
 {
 	struct sk_buff *skb;
 	struct ath_buf *bf;

 	list_for_each_entry(bf, &sc->rx.rxbuf, list) {
 		skb = bf->bf_mpdu;
 		if (skb)
 			dev_kfree_skb(skb);
 	}

 	if (sc->rx.rxdma.dd_desc_len != 0)
 		ath_descdma_cleanup(sc, &sc->rx.rxdma, &sc->rx.rxbuf);
 }

 /*
  * 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)
 {
 #define	RX_FILTER_PRESERVE (ATH9K_RX_FILTER_PHYERR | ATH9K_RX_FILTER_PHYRADAR)

 	u32 rfilt;

 	rfilt = (ath9k_hw_getrxfilter(sc->sc_ah) & RX_FILTER_PRESERVE)
 		| ATH9K_RX_FILTER_UCAST | ATH9K_RX_FILTER_BCAST
 		| ATH9K_RX_FILTER_MCAST;

 	/* If not a STA, enable processing of Probe Requests */
 	if (sc->sc_ah->ah_opmode != NL80211_IFTYPE_STATION)
 		rfilt |= ATH9K_RX_FILTER_PROBEREQ;

 	/* Can't set HOSTAP into promiscous mode */
 	if (((sc->sc_ah->ah_opmode != NL80211_IFTYPE_AP) &&
 	     (sc->rx.rxfilter & FIF_PROMISC_IN_BSS)) ||
 	    (sc->sc_ah->ah_opmode == NL80211_IFTYPE_MONITOR)) {
 		rfilt |= ATH9K_RX_FILTER_PROM;
 		/* ??? To prevent from sending ACK */
 		rfilt &= ~ATH9K_RX_FILTER_UCAST;
 	}

 	if (sc->sc_ah->ah_opmode == NL80211_IFTYPE_STATION ||
 	    sc->sc_ah->ah_opmode == NL80211_IFTYPE_ADHOC)
 		rfilt |= ATH9K_RX_FILTER_BEACON;

 	/* If in HOSTAP mode, want to enable reception of PSPOLL frames
 	   & beacon frames */
 	if (sc->sc_ah->ah_opmode == NL80211_IFTYPE_AP)
 		rfilt |= (ATH9K_RX_FILTER_BEACON | ATH9K_RX_FILTER_PSPOLL);

 	return rfilt;

 #undef RX_FILTER_PRESERVE
 }

 int ath_startrecv(struct ath_softc *sc)
 {
 	struct ath_hal *ah = sc->sc_ah;
 	struct ath_buf *bf, *tbf;

 	spin_lock_bh(&sc->rx.rxbuflock);
 	if (list_empty(&sc->rx.rxbuf))
 		goto start_recv;

 	sc->rx.rxlink = NULL;
 	list_for_each_entry_safe(bf, tbf, &sc->rx.rxbuf, list) {
 		ath_rx_buf_link(sc, bf);
 	}

 	/* 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_buf, list);
 	ath9k_hw_putrxbuf(ah, bf->bf_daddr);
 	ath9k_hw_rxena(ah);

 start_recv:
 	spin_unlock_bh(&sc->rx.rxbuflock);
 	ath_opmode_init(sc);
 	ath9k_hw_startpcureceive(ah);

 	return 0;
 }

 bool ath_stoprecv(struct ath_softc *sc)
 {
 	struct ath_hal *ah = sc->sc_ah;
 	bool stopped;

 	ath9k_hw_stoppcurecv(ah);
 	ath9k_hw_setrxfilter(ah, 0);
 	stopped = ath9k_hw_stopdmarecv(ah);
 	mdelay(3); /* 3ms is long enough for 1 frame */
 	sc->rx.rxlink = NULL;

 	return stopped;
 }

 void ath_flushrecv(struct ath_softc *sc)
 {
 	spin_lock_bh(&sc->rx.rxflushlock);
 	sc->sc_flags |= SC_OP_RXFLUSH;
 	ath_rx_tasklet(sc, 1);
 	sc->sc_flags &= ~SC_OP_RXFLUSH;
 	spin_unlock_bh(&sc->rx.rxflushlock);
 }

 int ath_rx_tasklet(struct ath_softc *sc, int flush)
 {
 #define PA2DESC(_sc, _pa)                                               \
 	((struct ath_desc *)((caddr_t)(_sc)->rx.rxdma.dd_desc +		\
 			     ((_pa) - (_sc)->rx.rxdma.dd_desc_paddr)))

 	struct ath_buf *bf;
 	struct ath_desc *ds;
 	struct sk_buff *skb = NULL, *requeue_skb;
 	struct ieee80211_rx_status rx_status;
 	struct ath_hal *ah = sc->sc_ah;
 	struct ieee80211_hdr *hdr;
 	int hdrlen, padsize, retval;
 	bool decrypt_error = false;
 	u8 keyix;

 	spin_lock_bh(&sc->rx.rxbuflock);

 	do {
 		/* If handling rx interrupt and flush is in progress => exit */
 		if ((sc->sc_flags & SC_OP_RXFLUSH) && (flush == 0))
 			break;

 		if (list_empty(&sc->rx.rxbuf)) {
 			sc->rx.rxlink = NULL;
 			break;
 		}

 		bf = list_first_entry(&sc->rx.rxbuf, struct ath_buf, list);
 		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.
 		 */
 		retval = ath9k_hw_rxprocdesc(ah, ds,
 					     bf->bf_daddr,
 					     PA2DESC(sc, ds->ds_link),
 					     0);
 		if (retval == -EINPROGRESS) {
 			struct ath_buf *tbf;
 			struct ath_desc *tds;

 			if (list_is_last(&bf->list, &sc->rx.rxbuf)) {
 				sc->rx.rxlink = NULL;
 				break;
 			}

 			tbf = list_entry(bf->list.next, struct ath_buf, 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;
 			retval = ath9k_hw_rxprocdesc(ah, tds, tbf->bf_daddr,
 					     PA2DESC(sc, tds->ds_link), 0);
 			if (retval == -EINPROGRESS) {
 				break;
 			}
 		}

 		skb = bf->bf_mpdu;
 		if (!skb)
 			continue;

 		/*
 		 * 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,
 				sc->rx.bufsize,
 				DMA_FROM_DEVICE);

 		/*
 		 * If we're asked to flush receive queue, directly
 		 * chain it back at the queue without processing it.
 		 */
 		if (flush)
 			goto requeue;

 		if (!ds->ds_rxstat.rs_datalen)
 			goto requeue;

 		/* The status portion of the descriptor could get corrupted. */
 		if (sc->rx.bufsize < ds->ds_rxstat.rs_datalen)
 			goto requeue;

 		if (!ath_rx_prepare(skb, ds, &rx_status, &decrypt_error, sc))
 			goto requeue;

 		/* Ensure we always have an skb to requeue once we are done
 		 * processing the current buffer's skb */
 		requeue_skb = ath_rxbuf_alloc(sc, sc->rx.bufsize);

 		/* 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)
 			goto requeue;

 		/* Unmap the frame */
 		dma_unmap_single(sc->dev, bf->bf_buf_addr,
 				 sc->rx.bufsize,
 				 DMA_FROM_DEVICE);

 		skb_put(skb, ds->ds_rxstat.rs_datalen);
 		skb->protocol = cpu_to_be16(ETH_P_CONTROL);

 		/* see if any padding is done by the hw and remove it */
 		hdr = (struct ieee80211_hdr *)skb->data;
 		hdrlen = ieee80211_get_hdrlen_from_skb(skb);

 		/* The MAC header is padded to have 32-bit boundary if the
 		 * packet payload is non-zero. The general calculation for
 		 * padsize would take into account odd header lengths:
 		 * padsize = (4 - hdrlen % 4) % 4; However, since only
 		 * even-length headers are used, padding can only be 0 or 2
 		 * bytes and we can optimize this a bit. In addition, we must
 		 * not try to remove padding from short control frames that do
 		 * not have payload. */
 		padsize = hdrlen & 3;
 		if (padsize && hdrlen >= 24) {
 			memmove(skb->data + padsize, skb->data, hdrlen);
 			skb_pull(skb, padsize);
 		}

 		keyix = ds->ds_rxstat.rs_keyix;

 		if (!(keyix == ATH9K_RXKEYIX_INVALID) && !decrypt_error) {
 			rx_status.flag |= RX_FLAG_DECRYPTED;
 		} else if ((le16_to_cpu(hdr->frame_control) & IEEE80211_FCTL_PROTECTED)
 			   && !decrypt_error && skb->len >= hdrlen + 4) {
 			keyix = skb->data[hdrlen + 3] >> 6;

 			if (test_bit(keyix, sc->sc_keymap))
 				rx_status.flag |= RX_FLAG_DECRYPTED;
 		}
 		if (ah->sw_mgmt_crypto &&
 		    (rx_status.flag & RX_FLAG_DECRYPTED) &&
 		    ieee80211_is_mgmt(hdr->frame_control)) {
 			/* Use software decrypt for management frames. */
 			rx_status.flag &= ~RX_FLAG_DECRYPTED;
 		}

 		/* Send the frame to mac80211 */
 		__ieee80211_rx(sc->hw, skb, &rx_status);

 		/* We will now give hardware our shiny new allocated skb */
 		bf->bf_mpdu = requeue_skb;
 		bf->bf_buf_addr = dma_map_single(sc->dev, requeue_skb->data,
 					 sc->rx.bufsize,
 					 DMA_FROM_DEVICE);
 		if (unlikely(dma_mapping_error(sc->dev,
 			  bf->bf_buf_addr))) {
 			dev_kfree_skb_any(requeue_skb);
 			bf->bf_mpdu = NULL;
 			DPRINTF(sc, ATH_DBG_CONFIG,
 				"dma_mapping_error() on RX\n");
 			break;
 		}
 		bf->bf_dmacontext = bf->bf_buf_addr;

 		/*
 		 * change the default rx antenna if rx diversity chooses the
 		 * other antenna 3 times in a row.
 		 */
 		if (sc->rx.defant != ds->ds_rxstat.rs_antenna) {
 			if (++sc->rx.rxotherant >= 3)
 				ath_setdefantenna(sc, ds->ds_rxstat.rs_antenna);
 		} else {
 			sc->rx.rxotherant = 0;
 		}
 requeue:
 		list_move_tail(&bf->list, &sc->rx.rxbuf);
 		ath_rx_buf_link(sc, bf);
 	} while (1);

 	spin_unlock_bh(&sc->rx.rxbuflock);

 	return 0;
 #undef PA2DESC
 }
	/*
	* Copyright (c) 2008 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 "core.h"

	/*
	* 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_buf bf)
	{
	struct ath_hal *ah = sc->sc_ah;
	struct ath_desc *ds;
	struct sk_buff *skb;

	ATH_RXBUF_RESET(bf);

	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;
	ASSERT(skb != NULL);
	ds->ds_vdata = skb->data;

	/* setup rx descriptors. The rx.bufsize here tells the harware
	* how much data it can DMA to us and that we are prepared
	* to process */
	ath9k_hw_setuprxdesc(ah, ds,
	sc->rx.bufsize,
	0);

	if (sc->rx.rxlink == NULL)
	ath9k_hw_putrxbuf(ah, bf->bf_daddr);
	else
	*sc->rx.rxlink = bf->bf_daddr;

	sc->rx.rxlink = &ds->ds_link;
	ath9k_hw_rxena(ah);
	}

	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;
	}

	/*
	* Extend 15-bit time stamp from rx descriptor to
	* a full 64-bit TSF using the current h/w TSF.
	*/
	static u64 ath_extend_tsf(struct ath_softc *sc, u32 rstamp)
	{
	u64 tsf;

	tsf = ath9k_hw_gettsf64(sc->sc_ah);
	if ((tsf & 0x7fff) < rstamp)
	tsf -= 0x8000;
	return (tsf & ~0x7fff) \| rstamp;
	}

	static struct sk_buff ath_rxbuf_alloc(struct ath_softc sc, u32 len)
	{
	struct sk_buff *skb;
	u32 off;

	/*
	* Cache-line-align. This is important (for the
	* 5210 at least) as not doing so causes bogus data
	* in rx'd frames.
	*/

	/* Note: the kernel can allocate a value greater than
	* what we ask it to give us. We really only need 4 KB as that
	* is this hardware supports and in fact we need at least 3849
	* as that is the MAX AMSDU size this hardware supports.
	* Unfortunately this means we may get 8 KB here from the
	* kernel... and that is actually what is observed on some
	* systems :( */
	skb = dev_alloc_skb(len + sc->sc_cachelsz - 1);
	if (skb != NULL) {
	off = ((unsigned long) skb->data) % sc->sc_cachelsz;
	if (off != 0)
	skb_reserve(skb, sc->sc_cachelsz - off);
	} else {
	DPRINTF(sc, ATH_DBG_FATAL,
	"skbuff alloc of size %u failed\n", len);
	return NULL;
	}

	return skb;
	}

	/*
	* 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 ath_rx_prepare(struct sk_buff skb, struct ath_desc ds,
	struct ieee80211_rx_status rx_status, bool decrypt_error,
	struct ath_softc *sc)
	{
	struct ieee80211_hdr *hdr;
	u8 ratecode;
	__le16 fc;

	hdr = (struct ieee80211_hdr *)skb->data;
	fc = hdr->frame_control;
	memset(rx_status, 0, sizeof(struct ieee80211_rx_status));

	if (ds->ds_rxstat.rs_more) {
	/*
	* Frame spans multiple descriptors; this cannot happen yet
	* as we don't support jumbograms. If not in monitor mode,
	* discard the frame. Enable this if you want to see
	* error frames in Monitor mode.
	*/
	if (sc->sc_ah->ah_opmode != NL80211_IFTYPE_MONITOR)
	goto rx_next;
	} else if (ds->ds_rxstat.rs_status != 0) {
	if (ds->ds_rxstat.rs_status & ATH9K_RXERR_CRC)
	rx_status->flag \|= RX_FLAG_FAILED_FCS_CRC;
	if (ds->ds_rxstat.rs_status & ATH9K_RXERR_PHY)
	goto rx_next;

	if (ds->ds_rxstat.rs_status & ATH9K_RXERR_DECRYPT) {
	*decrypt_error = true;
	} else if (ds->ds_rxstat.rs_status & ATH9K_RXERR_MIC) {
	if (ieee80211_is_ctl(fc))
	/*
	* Sometimes, we get invalid
	* MIC failures on valid control frames.
	* Remove these mic errors.
	*/
	ds->ds_rxstat.rs_status &= ~ATH9K_RXERR_MIC;
	else
	rx_status->flag \|= RX_FLAG_MMIC_ERROR;
	}
	/*
	* Reject error frames with the exception of
	* decryption and MIC failures. For monitor mode,
	* we also ignore the CRC error.
	*/
	if (sc->sc_ah->ah_opmode == NL80211_IFTYPE_MONITOR) {
	if (ds->ds_rxstat.rs_status &
	~(ATH9K_RXERR_DECRYPT \| ATH9K_RXERR_MIC \|
	ATH9K_RXERR_CRC))
	goto rx_next;
	} else {
	if (ds->ds_rxstat.rs_status &
	~(ATH9K_RXERR_DECRYPT \| ATH9K_RXERR_MIC)) {
	goto rx_next;
	}
	}
	}

	ratecode = ds->ds_rxstat.rs_rate;

	if (ratecode & 0x80) {
	/* HT rate */
	rx_status->flag \|= RX_FLAG_HT;
	if (ds->ds_rxstat.rs_flags & ATH9K_RX_2040)
	rx_status->flag \|= RX_FLAG_40MHZ;
	if (ds->ds_rxstat.rs_flags & ATH9K_RX_GI)
	rx_status->flag \|= RX_FLAG_SHORT_GI;
	rx_status->rate_idx = ratecode & 0x7f;
	} else {
	int i = 0, cur_band, n_rates;
	struct ieee80211_hw *hw = sc->hw;

	cur_band = hw->conf.channel->band;
	n_rates = sc->sbands[cur_band].n_bitrates;

	for (i = 0; i < n_rates; i++) {
	if (sc->sbands[cur_band].bitrates[i].hw_value ==
	ratecode) {
	rx_status->rate_idx = i;
	break;
	}

	if (sc->sbands[cur_band].bitrates[i].hw_value_short ==
	ratecode) {
	rx_status->rate_idx = i;
	rx_status->flag \|= RX_FLAG_SHORTPRE;
	break;
	}
	}
	}

	rx_status->mactime = ath_extend_tsf(sc, ds->ds_rxstat.rs_tstamp);
	rx_status->band = sc->hw->conf.channel->band;
	rx_status->freq = sc->hw->conf.channel->center_freq;
	rx_status->noise = sc->sc_ani.sc_noise_floor;
	rx_status->signal = rx_status->noise + ds->ds_rxstat.rs_rssi;
	rx_status->antenna = ds->ds_rxstat.rs_antenna;

	/* at 45 you will be able to use MCS 15 reliably. A more elaborate
	* scheme can be used here but it requires tables of SNR/throughput for
	* each possible mode used. */
	rx_status->qual = ds->ds_rxstat.rs_rssi * 100 / 45;

	/* rssi can be more than 45 though, anything above that
	* should be considered at 100% */
	if (rx_status->qual > 100)
	rx_status->qual = 100;

	rx_status->flag \|= RX_FLAG_TSFT;

	return 1;
	rx_next:
	return 0;
	}

	static void ath_opmode_init(struct ath_softc *sc)
	{
	struct ath_hal *ah = sc->sc_ah;
	u32 rfilt, mfilt[2];

	/* configure rx filter */
	rfilt = ath_calcrxfilter(sc);
	ath9k_hw_setrxfilter(ah, rfilt);

	/* configure bssid mask */
	if (ah->ah_caps.hw_caps & ATH9K_HW_CAP_BSSIDMASK)
	ath9k_hw_setbssidmask(ah, sc->sc_bssidmask);

	/* configure operational mode */
	ath9k_hw_setopmode(ah);

	/* Handle any link-level address change. */
	ath9k_hw_setmac(ah, sc->sc_myaddr);

	/* calculate and install multicast filter */
	mfilt[0] = mfilt[1] = ~0;
	ath9k_hw_setmcastfilter(ah, mfilt[0], mfilt[1]);
	}

	int ath_rx_init(struct ath_softc *sc, int nbufs)
	{
	struct sk_buff *skb;
	struct ath_buf *bf;
	int error = 0;

	do {
	spin_lock_init(&sc->rx.rxflushlock);
	sc->sc_flags &= ~SC_OP_RXFLUSH;
	spin_lock_init(&sc->rx.rxbuflock);

	sc->rx.bufsize = roundup(IEEE80211_MAX_MPDU_LEN,
	min(sc->sc_cachelsz,
	(u16)64));

	DPRINTF(sc, ATH_DBG_CONFIG, "cachelsz %u rxbufsize %u\n",
	sc->sc_cachelsz, sc->rx.bufsize);

	/* Initialize rx descriptors */

	error = ath_descdma_setup(sc, &sc->rx.rxdma, &sc->rx.rxbuf,
	"rx", nbufs, 1);
	if (error != 0) {
	DPRINTF(sc, ATH_DBG_FATAL,
	"failed to allocate rx descriptors: %d\n", error);
	break;
	}

	list_for_each_entry(bf, &sc->rx.rxbuf, list) {
	skb = ath_rxbuf_alloc(sc, sc->rx.bufsize);
	if (skb == NULL) {
	error = -ENOMEM;
	break;
	}

	bf->bf_mpdu = skb;
	bf->bf_buf_addr = dma_map_single(sc->dev, skb->data,
	sc->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;
	DPRINTF(sc, ATH_DBG_CONFIG,
	"dma_mapping_error() on RX init\n");
	error = -ENOMEM;
	break;
	}
	bf->bf_dmacontext = bf->bf_buf_addr;
	}
	sc->rx.rxlink = NULL;

	} while (0);

	if (error)
	ath_rx_cleanup(sc);

	return error;
	}

	void ath_rx_cleanup(struct ath_softc *sc)
	{
	struct sk_buff *skb;
	struct ath_buf *bf;

	list_for_each_entry(bf, &sc->rx.rxbuf, list) {
	skb = bf->bf_mpdu;
	if (skb)
	dev_kfree_skb(skb);
	}

	if (sc->rx.rxdma.dd_desc_len != 0)
	ath_descdma_cleanup(sc, &sc->rx.rxdma, &sc->rx.rxbuf);
	}

	/*
	* 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)
	{
	#define RX_FILTER_PRESERVE (ATH9K_RX_FILTER_PHYERR \| ATH9K_RX_FILTER_PHYRADAR)

	u32 rfilt;

	rfilt = (ath9k_hw_getrxfilter(sc->sc_ah) & RX_FILTER_PRESERVE)
	\| ATH9K_RX_FILTER_UCAST \| ATH9K_RX_FILTER_BCAST
	\| ATH9K_RX_FILTER_MCAST;

	/* If not a STA, enable processing of Probe Requests */
	if (sc->sc_ah->ah_opmode != NL80211_IFTYPE_STATION)
	rfilt \|= ATH9K_RX_FILTER_PROBEREQ;

	/* Can't set HOSTAP into promiscous mode */
	if (((sc->sc_ah->ah_opmode != NL80211_IFTYPE_AP) &&
	(sc->rx.rxfilter & FIF_PROMISC_IN_BSS)) \|\|
	(sc->sc_ah->ah_opmode == NL80211_IFTYPE_MONITOR)) {
	rfilt \|= ATH9K_RX_FILTER_PROM;
	/* ??? To prevent from sending ACK */
	rfilt &= ~ATH9K_RX_FILTER_UCAST;
	}

	if (sc->sc_ah->ah_opmode == NL80211_IFTYPE_STATION \|\|
	sc->sc_ah->ah_opmode == NL80211_IFTYPE_ADHOC)
	rfilt \|= ATH9K_RX_FILTER_BEACON;

	/* If in HOSTAP mode, want to enable reception of PSPOLL frames
	& beacon frames */
	if (sc->sc_ah->ah_opmode == NL80211_IFTYPE_AP)
	rfilt \|= (ATH9K_RX_FILTER_BEACON \| ATH9K_RX_FILTER_PSPOLL);

	return rfilt;

	#undef RX_FILTER_PRESERVE
	}

	int ath_startrecv(struct ath_softc *sc)
	{
	struct ath_hal *ah = sc->sc_ah;
	struct ath_buf bf, tbf;

	spin_lock_bh(&sc->rx.rxbuflock);
	if (list_empty(&sc->rx.rxbuf))
	goto start_recv;

	sc->rx.rxlink = NULL;
	list_for_each_entry_safe(bf, tbf, &sc->rx.rxbuf, list) {
	ath_rx_buf_link(sc, bf);
	}

	/* 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_buf, list);
	ath9k_hw_putrxbuf(ah, bf->bf_daddr);
	ath9k_hw_rxena(ah);

	start_recv:
	spin_unlock_bh(&sc->rx.rxbuflock);
	ath_opmode_init(sc);
	ath9k_hw_startpcureceive(ah);

	return 0;
	}

	bool ath_stoprecv(struct ath_softc *sc)
	{
	struct ath_hal *ah = sc->sc_ah;
	bool stopped;

	ath9k_hw_stoppcurecv(ah);
	ath9k_hw_setrxfilter(ah, 0);
	stopped = ath9k_hw_stopdmarecv(ah);
	mdelay(3); /* 3ms is long enough for 1 frame */
	sc->rx.rxlink = NULL;

	return stopped;
	}

	void ath_flushrecv(struct ath_softc *sc)
	{
	spin_lock_bh(&sc->rx.rxflushlock);
	sc->sc_flags \|= SC_OP_RXFLUSH;
	ath_rx_tasklet(sc, 1);
	sc->sc_flags &= ~SC_OP_RXFLUSH;
	spin_unlock_bh(&sc->rx.rxflushlock);
	}

	int ath_rx_tasklet(struct ath_softc *sc, int flush)
	{
	#define PA2DESC(_sc, _pa) \
	((struct ath_desc *)((caddr_t)(_sc)->rx.rxdma.dd_desc + \
	((_pa) - (_sc)->rx.rxdma.dd_desc_paddr)))

	struct ath_buf *bf;
	struct ath_desc *ds;
	struct sk_buff skb = NULL, requeue_skb;
	struct ieee80211_rx_status rx_status;
	struct ath_hal *ah = sc->sc_ah;
	struct ieee80211_hdr *hdr;
	int hdrlen, padsize, retval;
	bool decrypt_error = false;
	u8 keyix;

	spin_lock_bh(&sc->rx.rxbuflock);

	do {
	/* If handling rx interrupt and flush is in progress => exit */
	if ((sc->sc_flags & SC_OP_RXFLUSH) && (flush == 0))
	break;

	if (list_empty(&sc->rx.rxbuf)) {
	sc->rx.rxlink = NULL;
	break;
	}

	bf = list_first_entry(&sc->rx.rxbuf, struct ath_buf, list);
	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.
	*/
	retval = ath9k_hw_rxprocdesc(ah, ds,
	bf->bf_daddr,
	PA2DESC(sc, ds->ds_link),
	0);
	if (retval == -EINPROGRESS) {
	struct ath_buf *tbf;
	struct ath_desc *tds;

	if (list_is_last(&bf->list, &sc->rx.rxbuf)) {
	sc->rx.rxlink = NULL;
	break;
	}

	tbf = list_entry(bf->list.next, struct ath_buf, 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;
	retval = ath9k_hw_rxprocdesc(ah, tds, tbf->bf_daddr,
	PA2DESC(sc, tds->ds_link), 0);
	if (retval == -EINPROGRESS) {
	break;
	}
	}

	skb = bf->bf_mpdu;
	if (!skb)
	continue;

	/*
	* 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,
	sc->rx.bufsize,
	DMA_FROM_DEVICE);

	/*
	* If we're asked to flush receive queue, directly
	* chain it back at the queue without processing it.
	*/
	if (flush)
	goto requeue;

	if (!ds->ds_rxstat.rs_datalen)
	goto requeue;

	/* The status portion of the descriptor could get corrupted. */
	if (sc->rx.bufsize < ds->ds_rxstat.rs_datalen)
	goto requeue;

	if (!ath_rx_prepare(skb, ds, &rx_status, &decrypt_error, sc))
	goto requeue;

	/* Ensure we always have an skb to requeue once we are done
	* processing the current buffer's skb */
	requeue_skb = ath_rxbuf_alloc(sc, sc->rx.bufsize);

	/* 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)
	goto requeue;

	/* Unmap the frame */
	dma_unmap_single(sc->dev, bf->bf_buf_addr,
	sc->rx.bufsize,
	DMA_FROM_DEVICE);

	skb_put(skb, ds->ds_rxstat.rs_datalen);
	skb->protocol = cpu_to_be16(ETH_P_CONTROL);

	/* see if any padding is done by the hw and remove it */
	hdr = (struct ieee80211_hdr *)skb->data;
	hdrlen = ieee80211_get_hdrlen_from_skb(skb);

	/* The MAC header is padded to have 32-bit boundary if the
	* packet payload is non-zero. The general calculation for
	* padsize would take into account odd header lengths:
	* padsize = (4 - hdrlen % 4) % 4; However, since only
	* even-length headers are used, padding can only be 0 or 2
	* bytes and we can optimize this a bit. In addition, we must
	* not try to remove padding from short control frames that do
	* not have payload. */
	padsize = hdrlen & 3;
	if (padsize && hdrlen >= 24) {
	memmove(skb->data + padsize, skb->data, hdrlen);
	skb_pull(skb, padsize);
	}

	keyix = ds->ds_rxstat.rs_keyix;

	if (!(keyix == ATH9K_RXKEYIX_INVALID) && !decrypt_error) {
	rx_status.flag \|= RX_FLAG_DECRYPTED;
	} else if ((le16_to_cpu(hdr->frame_control) & IEEE80211_FCTL_PROTECTED)
	&& !decrypt_error && skb->len >= hdrlen + 4) {
	keyix = skb->data[hdrlen + 3] >> 6;

	if (test_bit(keyix, sc->sc_keymap))
	rx_status.flag \|= RX_FLAG_DECRYPTED;
	}
	if (ah->sw_mgmt_crypto &&
	(rx_status.flag & RX_FLAG_DECRYPTED) &&
	ieee80211_is_mgmt(hdr->frame_control)) {
	/* Use software decrypt for management frames. */
	rx_status.flag &= ~RX_FLAG_DECRYPTED;
	}

	/* Send the frame to mac80211 */
	__ieee80211_rx(sc->hw, skb, &rx_status);

	/* We will now give hardware our shiny new allocated skb */
	bf->bf_mpdu = requeue_skb;
	bf->bf_buf_addr = dma_map_single(sc->dev, requeue_skb->data,
	sc->rx.bufsize,
	DMA_FROM_DEVICE);
	if (unlikely(dma_mapping_error(sc->dev,
	bf->bf_buf_addr))) {
	dev_kfree_skb_any(requeue_skb);
	bf->bf_mpdu = NULL;
	DPRINTF(sc, ATH_DBG_CONFIG,
	"dma_mapping_error() on RX\n");
	break;
	}
	bf->bf_dmacontext = bf->bf_buf_addr;

	/*
	* change the default rx antenna if rx diversity chooses the
	* other antenna 3 times in a row.
	*/
	if (sc->rx.defant != ds->ds_rxstat.rs_antenna) {
	if (++sc->rx.rxotherant >= 3)
	ath_setdefantenna(sc, ds->ds_rxstat.rs_antenna);
	} else {
	sc->rx.rxotherant = 0;
	}
	requeue:
	list_move_tail(&bf->list, &sc->rx.rxbuf);
	ath_rx_buf_link(sc, bf);
	} while (1);

	spin_unlock_bh(&sc->rx.rxbuflock);

	return 0;
	#undef PA2DESC
	}