Adding upstream version 6.1.76.upstream/6.1.76

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 1719 insertions, 0 deletions

diff --git a/drivers/net/wireless/ath/carl9170/tx.c b/drivers/net/wireless/ath/carl9170/tx.c
new file mode 100644
index 000000000..6bb9aa2bf
--- /dev/null
+++ b/drivers/net/wireless/ath/carl9170/tx.c
@@ -0,0 +1,1719 @@
+/*
+ * Atheros CARL9170 driver
+ *
+ * 802.11 xmit & status routines
+ *
+ * Copyright 2008, Johannes Berg <johannes@sipsolutions.net>
+ * Copyright 2009, 2010, Christian Lamparter <chunkeey@googlemail.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; see the file COPYING.  If not, see
+ * http://www.gnu.org/licenses/.
+ *
+ * This file incorporates work covered by the following copyright and
+ * permission notice:
+ *    Copyright (c) 2007-2008 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 <linux/slab.h>
+#include <linux/module.h>
+#include <linux/etherdevice.h>
+#include <net/mac80211.h>
+#include "carl9170.h"
+#include "hw.h"
+#include "cmd.h"
+
+static inline unsigned int __carl9170_get_queue(struct ar9170 *ar,
+						unsigned int queue)
+{
+	if (unlikely(modparam_noht)) {
+		return queue;
+	} else {
+		/*
+		 * This is just another workaround, until
+		 * someone figures out how to get QoS and
+		 * AMPDU to play nicely together.
+		 */
+
+		return 2;		/* AC_BE */
+	}
+}
+
+static inline unsigned int carl9170_get_queue(struct ar9170 *ar,
+					      struct sk_buff *skb)
+{
+	return __carl9170_get_queue(ar, skb_get_queue_mapping(skb));
+}
+
+static bool is_mem_full(struct ar9170 *ar)
+{
+	return (DIV_ROUND_UP(IEEE80211_MAX_FRAME_LEN, ar->fw.mem_block_size) >
+		atomic_read(&ar->mem_free_blocks));
+}
+
+static void carl9170_tx_accounting(struct ar9170 *ar, struct sk_buff *skb)
+{
+	int queue, i;
+	bool mem_full;
+
+	atomic_inc(&ar->tx_total_queued);
+
+	queue = skb_get_queue_mapping(skb);
+	spin_lock_bh(&ar->tx_stats_lock);
+
+	/*
+	 * The driver has to accept the frame, regardless if the queue is
+	 * full to the brim, or not. We have to do the queuing internally,
+	 * since mac80211 assumes that a driver which can operate with
+	 * aggregated frames does not reject frames for this reason.
+	 */
+	ar->tx_stats[queue].len++;
+	ar->tx_stats[queue].count++;
+
+	mem_full = is_mem_full(ar);
+	for (i = 0; i < ar->hw->queues; i++) {
+		if (mem_full || ar->tx_stats[i].len >= ar->tx_stats[i].limit) {
+			ieee80211_stop_queue(ar->hw, i);
+			ar->queue_stop_timeout[i] = jiffies;
+		}
+	}
+
+	spin_unlock_bh(&ar->tx_stats_lock);
+}
+
+/* needs rcu_read_lock */
+static struct ieee80211_sta *__carl9170_get_tx_sta(struct ar9170 *ar,
+						   struct sk_buff *skb)
+{
+	struct _carl9170_tx_superframe *super = (void *) skb->data;
+	struct ieee80211_hdr *hdr = (void *) super->frame_data;
+	struct ieee80211_vif *vif;
+	unsigned int vif_id;
+
+	vif_id = (super->s.misc & CARL9170_TX_SUPER_MISC_VIF_ID) >>
+		 CARL9170_TX_SUPER_MISC_VIF_ID_S;
+
+	if (WARN_ON_ONCE(vif_id >= AR9170_MAX_VIRTUAL_MAC))
+		return NULL;
+
+	vif = rcu_dereference(ar->vif_priv[vif_id].vif);
+	if (unlikely(!vif))
+		return NULL;
+
+	/*
+	 * Normally we should use wrappers like ieee80211_get_DA to get
+	 * the correct peer ieee80211_sta.
+	 *
+	 * But there is a problem with indirect traffic (broadcasts, or
+	 * data which is designated for other stations) in station mode.
+	 * The frame will be directed to the AP for distribution and not
+	 * to the actual destination.
+	 */
+
+	return ieee80211_find_sta(vif, hdr->addr1);
+}
+
+static void carl9170_tx_ps_unblock(struct ar9170 *ar, struct sk_buff *skb)
+{
+	struct ieee80211_sta *sta;
+	struct carl9170_sta_info *sta_info;
+
+	rcu_read_lock();
+	sta = __carl9170_get_tx_sta(ar, skb);
+	if (unlikely(!sta))
+		goto out_rcu;
+
+	sta_info = (struct carl9170_sta_info *) sta->drv_priv;
+	if (atomic_dec_return(&sta_info->pending_frames) == 0)
+		ieee80211_sta_block_awake(ar->hw, sta, false);
+
+out_rcu:
+	rcu_read_unlock();
+}
+
+static void carl9170_tx_accounting_free(struct ar9170 *ar, struct sk_buff *skb)
+{
+	int queue;
+
+	queue = skb_get_queue_mapping(skb);
+
+	spin_lock_bh(&ar->tx_stats_lock);
+
+	ar->tx_stats[queue].len--;
+
+	if (!is_mem_full(ar)) {
+		unsigned int i;
+		for (i = 0; i < ar->hw->queues; i++) {
+			if (ar->tx_stats[i].len >= CARL9170_NUM_TX_LIMIT_SOFT)
+				continue;
+
+			if (ieee80211_queue_stopped(ar->hw, i)) {
+				unsigned long tmp;
+
+				tmp = jiffies - ar->queue_stop_timeout[i];
+				if (tmp > ar->max_queue_stop_timeout[i])
+					ar->max_queue_stop_timeout[i] = tmp;
+			}
+
+			ieee80211_wake_queue(ar->hw, i);
+		}
+	}
+
+	spin_unlock_bh(&ar->tx_stats_lock);
+
+	if (atomic_dec_and_test(&ar->tx_total_queued))
+		complete(&ar->tx_flush);
+}
+
+static int carl9170_alloc_dev_space(struct ar9170 *ar, struct sk_buff *skb)
+{
+	struct _carl9170_tx_superframe *super = (void *) skb->data;
+	unsigned int chunks;
+	int cookie = -1;
+
+	atomic_inc(&ar->mem_allocs);
+
+	chunks = DIV_ROUND_UP(skb->len, ar->fw.mem_block_size);
+	if (unlikely(atomic_sub_return(chunks, &ar->mem_free_blocks) < 0)) {
+		atomic_add(chunks, &ar->mem_free_blocks);
+		return -ENOSPC;
+	}
+
+	spin_lock_bh(&ar->mem_lock);
+	cookie = bitmap_find_free_region(ar->mem_bitmap, ar->fw.mem_blocks, 0);
+	spin_unlock_bh(&ar->mem_lock);
+
+	if (unlikely(cookie < 0)) {
+		atomic_add(chunks, &ar->mem_free_blocks);
+		return -ENOSPC;
+	}
+
+	super = (void *) skb->data;
+
+	/*
+	 * Cookie #0 serves two special purposes:
+	 *  1. The firmware might use it generate BlockACK frames
+	 *     in responds of an incoming BlockAckReqs.
+	 *
+	 *  2. Prevent double-free bugs.
+	 */
+	super->s.cookie = (u8) cookie + 1;
+	return 0;
+}
+
+static void carl9170_release_dev_space(struct ar9170 *ar, struct sk_buff *skb)
+{
+	struct _carl9170_tx_superframe *super = (void *) skb->data;
+	int cookie;
+
+	/* make a local copy of the cookie */
+	cookie = super->s.cookie;
+	/* invalidate cookie */
+	super->s.cookie = 0;
+
+	/*
+	 * Do a out-of-bounds check on the cookie:
+	 *
+	 *  * cookie "0" is reserved and won't be assigned to any
+	 *    out-going frame. Internally however, it is used to
+	 *    mark no longer/un-accounted frames and serves as a
+	 *    cheap way of preventing frames from being freed
+	 *    twice by _accident_. NB: There is a tiny race...
+	 *
+	 *  * obviously, cookie number is limited by the amount
+	 *    of available memory blocks, so the number can
+	 *    never execeed the mem_blocks count.
+	 */
+	if (WARN_ON_ONCE(cookie == 0) ||
+	    WARN_ON_ONCE(cookie > ar->fw.mem_blocks))
+		return;
+
+	atomic_add(DIV_ROUND_UP(skb->len, ar->fw.mem_block_size),
+		   &ar->mem_free_blocks);
+
+	spin_lock_bh(&ar->mem_lock);
+	bitmap_release_region(ar->mem_bitmap, cookie - 1, 0);
+	spin_unlock_bh(&ar->mem_lock);
+}
+
+/* Called from any context */
+static void carl9170_tx_release(struct kref *ref)
+{
+	struct ar9170 *ar;
+	struct carl9170_tx_info *arinfo;
+	struct ieee80211_tx_info *txinfo;
+	struct sk_buff *skb;
+
+	arinfo = container_of(ref, struct carl9170_tx_info, ref);
+	txinfo = container_of((void *) arinfo, struct ieee80211_tx_info,
+			      rate_driver_data);
+	skb = container_of((void *) txinfo, struct sk_buff, cb);
+
+	ar = arinfo->ar;
+	if (WARN_ON_ONCE(!ar))
+		return;
+
+	/*
+	 * This does not call ieee80211_tx_info_clear_status() because
+	 * carl9170_tx_fill_rateinfo() has filled the rate information
+	 * before we get to this point.
+	 */
+	memset_after(&txinfo->status, 0, rates);
+
+	if (atomic_read(&ar->tx_total_queued))
+		ar->tx_schedule = true;
+
+	if (txinfo->flags & IEEE80211_TX_CTL_AMPDU) {
+		if (!atomic_read(&ar->tx_ampdu_upload))
+			ar->tx_ampdu_schedule = true;
+
+		if (txinfo->flags & IEEE80211_TX_STAT_AMPDU) {
+			struct _carl9170_tx_superframe *super;
+
+			super = (void *)skb->data;
+			txinfo->status.ampdu_len = super->s.rix;
+			txinfo->status.ampdu_ack_len = super->s.cnt;
+		} else if ((txinfo->flags & IEEE80211_TX_STAT_ACK) &&
+			   !(txinfo->flags & IEEE80211_TX_CTL_REQ_TX_STATUS)) {
+			/*
+			 * drop redundant tx_status reports:
+			 *
+			 * 1. ampdu_ack_len of the final tx_status does
+			 *    include the feedback of this particular frame.
+			 *
+			 * 2. tx_status_irqsafe only queues up to 128
+			 *    tx feedback reports and discards the rest.
+			 *
+			 * 3. minstrel_ht is picky, it only accepts
+			 *    reports of frames with the TX_STATUS_AMPDU flag.
+			 *
+			 * 4. mac80211 is not particularly interested in
+			 *    feedback either [CTL_REQ_TX_STATUS not set]
+			 */
+
+			ieee80211_free_txskb(ar->hw, skb);
+			return;
+		} else {
+			/*
+			 * Either the frame transmission has failed or
+			 * mac80211 requested tx status.
+			 */
+		}
+	}
+
+	skb_pull(skb, sizeof(struct _carl9170_tx_superframe));
+	ieee80211_tx_status_irqsafe(ar->hw, skb);
+}
+
+void carl9170_tx_get_skb(struct sk_buff *skb)
+{
+	struct carl9170_tx_info *arinfo = (void *)
+		(IEEE80211_SKB_CB(skb))->rate_driver_data;
+	kref_get(&arinfo->ref);
+}
+
+int carl9170_tx_put_skb(struct sk_buff *skb)
+{
+	struct carl9170_tx_info *arinfo = (void *)
+		(IEEE80211_SKB_CB(skb))->rate_driver_data;
+
+	return kref_put(&arinfo->ref, carl9170_tx_release);
+}
+
+/* Caller must hold the tid_info->lock & rcu_read_lock */
+static void carl9170_tx_shift_bm(struct ar9170 *ar,
+	struct carl9170_sta_tid *tid_info, u16 seq)
+{
+	u16 off;
+
+	off = SEQ_DIFF(seq, tid_info->bsn);
+
+	if (WARN_ON_ONCE(off >= CARL9170_BAW_BITS))
+		return;
+
+	/*
+	 * Sanity check. For each MPDU we set the bit in bitmap and
+	 * clear it once we received the tx_status.
+	 * But if the bit is already cleared then we've been bitten
+	 * by a bug.
+	 */
+	WARN_ON_ONCE(!test_and_clear_bit(off, tid_info->bitmap));
+
+	off = SEQ_DIFF(tid_info->snx, tid_info->bsn);
+	if (WARN_ON_ONCE(off >= CARL9170_BAW_BITS))
+		return;
+
+	if (!bitmap_empty(tid_info->bitmap, off))
+		off = find_first_bit(tid_info->bitmap, off);
+
+	tid_info->bsn += off;
+	tid_info->bsn &= 0x0fff;
+
+	bitmap_shift_right(tid_info->bitmap, tid_info->bitmap,
+			   off, CARL9170_BAW_BITS);
+}
+
+static void carl9170_tx_status_process_ampdu(struct ar9170 *ar,
+	struct sk_buff *skb, struct ieee80211_tx_info *txinfo)
+{
+	struct _carl9170_tx_superframe *super = (void *) skb->data;
+	struct ieee80211_hdr *hdr = (void *) super->frame_data;
+	struct ieee80211_sta *sta;
+	struct carl9170_sta_info *sta_info;
+	struct carl9170_sta_tid *tid_info;
+	u8 tid;
+
+	if (!(txinfo->flags & IEEE80211_TX_CTL_AMPDU) ||
+	    txinfo->flags & IEEE80211_TX_CTL_INJECTED)
+		return;
+
+	rcu_read_lock();
+	sta = __carl9170_get_tx_sta(ar, skb);
+	if (unlikely(!sta))
+		goto out_rcu;
+
+	tid = ieee80211_get_tid(hdr);
+
+	sta_info = (void *) sta->drv_priv;
+	tid_info = rcu_dereference(sta_info->agg[tid]);
+	if (!tid_info)
+		goto out_rcu;
+
+	spin_lock_bh(&tid_info->lock);
+	if (likely(tid_info->state >= CARL9170_TID_STATE_IDLE))
+		carl9170_tx_shift_bm(ar, tid_info, get_seq_h(hdr));
+
+	if (sta_info->stats[tid].clear) {
+		sta_info->stats[tid].clear = false;
+		sta_info->stats[tid].req = false;
+		sta_info->stats[tid].ampdu_len = 0;
+		sta_info->stats[tid].ampdu_ack_len = 0;
+	}
+
+	sta_info->stats[tid].ampdu_len++;
+	if (txinfo->status.rates[0].count == 1)
+		sta_info->stats[tid].ampdu_ack_len++;
+
+	if (!(txinfo->flags & IEEE80211_TX_STAT_ACK))
+		sta_info->stats[tid].req = true;
+
+	if (super->f.mac_control & cpu_to_le16(AR9170_TX_MAC_IMM_BA)) {
+		super->s.rix = sta_info->stats[tid].ampdu_len;
+		super->s.cnt = sta_info->stats[tid].ampdu_ack_len;
+		txinfo->flags |= IEEE80211_TX_STAT_AMPDU;
+		if (sta_info->stats[tid].req)
+			txinfo->flags |= IEEE80211_TX_STAT_AMPDU_NO_BACK;
+
+		sta_info->stats[tid].clear = true;
+	}
+	spin_unlock_bh(&tid_info->lock);
+
+out_rcu:
+	rcu_read_unlock();
+}
+
+static void carl9170_tx_bar_status(struct ar9170 *ar, struct sk_buff *skb,
+	struct ieee80211_tx_info *tx_info)
+{
+	struct _carl9170_tx_superframe *super = (void *) skb->data;
+	struct ieee80211_bar *bar = (void *) super->frame_data;
+
+	/*
+	 * Unlike all other frames, the status report for BARs does
+	 * not directly come from the hardware as it is incapable of
+	 * matching a BA to a previously send BAR.
+	 * Instead the RX-path will scan for incoming BAs and set the
+	 * IEEE80211_TX_STAT_ACK if it sees one that was likely
+	 * caused by a BAR from us.
+	 */
+
+	if (unlikely(ieee80211_is_back_req(bar->frame_control)) &&
+	   !(tx_info->flags & IEEE80211_TX_STAT_ACK)) {
+		struct carl9170_bar_list_entry *entry;
+		int queue = skb_get_queue_mapping(skb);
+
+		rcu_read_lock();
+		list_for_each_entry_rcu(entry, &ar->bar_list[queue], list) {
+			if (entry->skb == skb) {
+				spin_lock_bh(&ar->bar_list_lock[queue]);
+				list_del_rcu(&entry->list);
+				spin_unlock_bh(&ar->bar_list_lock[queue]);
+				kfree_rcu(entry, head);
+				goto out;
+			}
+		}
+
+		WARN(1, "bar not found in %d - ra:%pM ta:%pM c:%x ssn:%x\n",
+		       queue, bar->ra, bar->ta, bar->control,
+			bar->start_seq_num);
+out:
+		rcu_read_unlock();
+	}
+}
+
+void carl9170_tx_status(struct ar9170 *ar, struct sk_buff *skb,
+			const bool success)
+{
+	struct ieee80211_tx_info *txinfo;
+
+	carl9170_tx_accounting_free(ar, skb);
+
+	txinfo = IEEE80211_SKB_CB(skb);
+
+	carl9170_tx_bar_status(ar, skb, txinfo);
+
+	if (success)
+		txinfo->flags |= IEEE80211_TX_STAT_ACK;
+	else
+		ar->tx_ack_failures++;
+
+	if (txinfo->flags & IEEE80211_TX_CTL_AMPDU)
+		carl9170_tx_status_process_ampdu(ar, skb, txinfo);
+
+	carl9170_tx_ps_unblock(ar, skb);
+	carl9170_tx_put_skb(skb);
+}
+
+/* This function may be called form any context */
+void carl9170_tx_callback(struct ar9170 *ar, struct sk_buff *skb)
+{
+	struct ieee80211_tx_info *txinfo = IEEE80211_SKB_CB(skb);
+
+	atomic_dec(&ar->tx_total_pending);
+
+	if (txinfo->flags & IEEE80211_TX_CTL_AMPDU)
+		atomic_dec(&ar->tx_ampdu_upload);
+
+	if (carl9170_tx_put_skb(skb))
+		tasklet_hi_schedule(&ar->usb_tasklet);
+}
+
+static struct sk_buff *carl9170_get_queued_skb(struct ar9170 *ar, u8 cookie,
+					       struct sk_buff_head *queue)
+{
+	struct sk_buff *skb;
+
+	spin_lock_bh(&queue->lock);
+	skb_queue_walk(queue, skb) {
+		struct _carl9170_tx_superframe *txc = (void *) skb->data;
+
+		if (txc->s.cookie != cookie)
+			continue;
+
+		__skb_unlink(skb, queue);
+		spin_unlock_bh(&queue->lock);
+
+		carl9170_release_dev_space(ar, skb);
+		return skb;
+	}
+	spin_unlock_bh(&queue->lock);
+
+	return NULL;
+}
+
+static void carl9170_tx_fill_rateinfo(struct ar9170 *ar, unsigned int rix,
+	unsigned int tries, struct ieee80211_tx_info *txinfo)
+{
+	unsigned int i;
+
+	for (i = 0; i < IEEE80211_TX_MAX_RATES; i++) {
+		if (txinfo->status.rates[i].idx < 0)
+			break;
+
+		if (i == rix) {
+			txinfo->status.rates[i].count = tries;
+			i++;
+			break;
+		}
+	}
+
+	for (; i < IEEE80211_TX_MAX_RATES; i++) {
+		txinfo->status.rates[i].idx = -1;
+		txinfo->status.rates[i].count = 0;
+	}
+}
+
+static void carl9170_check_queue_stop_timeout(struct ar9170 *ar)
+{
+	int i;
+	struct sk_buff *skb;
+	struct ieee80211_tx_info *txinfo;
+	struct carl9170_tx_info *arinfo;
+	bool restart = false;
+
+	for (i = 0; i < ar->hw->queues; i++) {
+		spin_lock_bh(&ar->tx_status[i].lock);
+
+		skb = skb_peek(&ar->tx_status[i]);
+
+		if (!skb)
+			goto next;
+
+		txinfo = IEEE80211_SKB_CB(skb);
+		arinfo = (void *) txinfo->rate_driver_data;
+
+		if (time_is_before_jiffies(arinfo->timeout +
+		    msecs_to_jiffies(CARL9170_QUEUE_STUCK_TIMEOUT)) == true)
+			restart = true;
+
+next:
+		spin_unlock_bh(&ar->tx_status[i].lock);
+	}
+
+	if (restart) {
+		/*
+		 * At least one queue has been stuck for long enough.
+		 * Give the device a kick and hope it gets back to
+		 * work.
+		 *
+		 * possible reasons may include:
+		 *  - frames got lost/corrupted (bad connection to the device)
+		 *  - stalled rx processing/usb controller hiccups
+		 *  - firmware errors/bugs
+		 *  - every bug you can think of.
+		 *  - all bugs you can't...
+		 *  - ...
+		 */
+		carl9170_restart(ar, CARL9170_RR_STUCK_TX);
+	}
+}
+
+static void carl9170_tx_ampdu_timeout(struct ar9170 *ar)
+{
+	struct carl9170_sta_tid *iter;
+	struct sk_buff *skb;
+	struct ieee80211_tx_info *txinfo;
+	struct carl9170_tx_info *arinfo;
+	struct ieee80211_sta *sta;
+
+	rcu_read_lock();
+	list_for_each_entry_rcu(iter, &ar->tx_ampdu_list, list) {
+		if (iter->state < CARL9170_TID_STATE_IDLE)
+			continue;
+
+		spin_lock_bh(&iter->lock);
+		skb = skb_peek(&iter->queue);
+		if (!skb)
+			goto unlock;
+
+		txinfo = IEEE80211_SKB_CB(skb);
+		arinfo = (void *)txinfo->rate_driver_data;
+		if (time_is_after_jiffies(arinfo->timeout +
+		    msecs_to_jiffies(CARL9170_QUEUE_TIMEOUT)))
+			goto unlock;
+
+		sta = iter->sta;
+		if (WARN_ON(!sta))
+			goto unlock;
+
+		ieee80211_stop_tx_ba_session(sta, iter->tid);
+unlock:
+		spin_unlock_bh(&iter->lock);
+
+	}
+	rcu_read_unlock();
+}
+
+void carl9170_tx_janitor(struct work_struct *work)
+{
+	struct ar9170 *ar = container_of(work, struct ar9170,
+					 tx_janitor.work);
+	if (!IS_STARTED(ar))
+		return;
+
+	ar->tx_janitor_last_run = jiffies;
+
+	carl9170_check_queue_stop_timeout(ar);
+	carl9170_tx_ampdu_timeout(ar);
+
+	if (!atomic_read(&ar->tx_total_queued))
+		return;
+
+	ieee80211_queue_delayed_work(ar->hw, &ar->tx_janitor,
+		msecs_to_jiffies(CARL9170_TX_TIMEOUT));
+}
+
+static void __carl9170_tx_process_status(struct ar9170 *ar,
+	const uint8_t cookie, const uint8_t info)
+{
+	struct sk_buff *skb;
+	struct ieee80211_tx_info *txinfo;
+	unsigned int r, t, q;
+	bool success = true;
+
+	q = ar9170_qmap(info & CARL9170_TX_STATUS_QUEUE);
+
+	skb = carl9170_get_queued_skb(ar, cookie, &ar->tx_status[q]);
+	if (!skb) {
+		/*
+		 * We have lost the race to another thread.
+		 */
+
+		return ;
+	}
+
+	txinfo = IEEE80211_SKB_CB(skb);
+
+	if (!(info & CARL9170_TX_STATUS_SUCCESS))
+		success = false;
+
+	r = (info & CARL9170_TX_STATUS_RIX) >> CARL9170_TX_STATUS_RIX_S;
+	t = (info & CARL9170_TX_STATUS_TRIES) >> CARL9170_TX_STATUS_TRIES_S;
+
+	carl9170_tx_fill_rateinfo(ar, r, t, txinfo);
+	carl9170_tx_status(ar, skb, success);
+}
+
+void carl9170_tx_process_status(struct ar9170 *ar,
+				const struct carl9170_rsp *cmd)
+{
+	unsigned int i;
+
+	for (i = 0;  i < cmd->hdr.ext; i++) {
+		if (WARN_ON(i > ((cmd->hdr.len / 2) + 1))) {
+			print_hex_dump_bytes("UU:", DUMP_PREFIX_NONE,
+					     (void *) cmd, cmd->hdr.len + 4);
+			break;
+		}
+
+		__carl9170_tx_process_status(ar, cmd->_tx_status[i].cookie,
+					     cmd->_tx_status[i].info);
+	}
+}
+
+static void carl9170_tx_rate_tpc_chains(struct ar9170 *ar,
+	struct ieee80211_tx_info *info,	struct ieee80211_tx_rate *txrate,
+	unsigned int *phyrate, unsigned int *tpc, unsigned int *chains)
+{
+	struct ieee80211_rate *rate = NULL;
+	u8 *txpower;
+	unsigned int idx;
+
+	idx = txrate->idx;
+	*tpc = 0;
+	*phyrate = 0;
+
+	if (txrate->flags & IEEE80211_TX_RC_MCS) {
+		if (txrate->flags & IEEE80211_TX_RC_40_MHZ_WIDTH) {
+			/* +1 dBm for HT40 */
+			*tpc += 2;
+
+			if (info->band == NL80211_BAND_2GHZ)
+				txpower = ar->power_2G_ht40;
+			else
+				txpower = ar->power_5G_ht40;
+		} else {
+			if (info->band == NL80211_BAND_2GHZ)
+				txpower = ar->power_2G_ht20;
+			else
+				txpower = ar->power_5G_ht20;
+		}
+
+		*phyrate = txrate->idx;
+		*tpc += txpower[idx & 7];
+	} else {
+		if (info->band == NL80211_BAND_2GHZ) {
+			if (idx < 4)
+				txpower = ar->power_2G_cck;
+			else
+				txpower = ar->power_2G_ofdm;
+		} else {
+			txpower = ar->power_5G_leg;
+			idx += 4;
+		}
+
+		rate = &__carl9170_ratetable[idx];
+		*tpc += txpower[(rate->hw_value & 0x30) >> 4];
+		*phyrate = rate->hw_value & 0xf;
+	}
+
+	if (ar->eeprom.tx_mask == 1) {
+		*chains = AR9170_TX_PHY_TXCHAIN_1;
+	} else {
+		if (!(txrate->flags & IEEE80211_TX_RC_MCS) &&
+		    rate && rate->bitrate >= 360)
+			*chains = AR9170_TX_PHY_TXCHAIN_1;
+		else
+			*chains = AR9170_TX_PHY_TXCHAIN_2;
+	}
+
+	*tpc = min_t(unsigned int, *tpc, ar->hw->conf.power_level * 2);
+}
+
+static __le32 carl9170_tx_physet(struct ar9170 *ar,
+	struct ieee80211_tx_info *info, struct ieee80211_tx_rate *txrate)
+{
+	unsigned int power = 0, chains = 0, phyrate = 0;
+	__le32 tmp;
+
+	tmp = cpu_to_le32(0);
+
+	if (txrate->flags & IEEE80211_TX_RC_40_MHZ_WIDTH)
+		tmp |= cpu_to_le32(AR9170_TX_PHY_BW_40MHZ <<
+			AR9170_TX_PHY_BW_S);
+	/* this works because 40 MHz is 2 and dup is 3 */
+	if (txrate->flags & IEEE80211_TX_RC_DUP_DATA)
+		tmp |= cpu_to_le32(AR9170_TX_PHY_BW_40MHZ_DUP <<
+			AR9170_TX_PHY_BW_S);
+
+	if (txrate->flags & IEEE80211_TX_RC_SHORT_GI)
+		tmp |= cpu_to_le32(AR9170_TX_PHY_SHORT_GI);
+
+	if (txrate->flags & IEEE80211_TX_RC_MCS) {
+		SET_VAL(AR9170_TX_PHY_MCS, phyrate, txrate->idx);
+
+		/* heavy clip control */
+		tmp |= cpu_to_le32((txrate->idx & 0x7) <<
+			AR9170_TX_PHY_TX_HEAVY_CLIP_S);
+
+		tmp |= cpu_to_le32(AR9170_TX_PHY_MOD_HT);
+
+		/*
+		 * green field preamble does not work.
+		 *
+		 * if (txrate->flags & IEEE80211_TX_RC_GREEN_FIELD)
+		 * tmp |= cpu_to_le32(AR9170_TX_PHY_GREENFIELD);
+		 */
+	} else {
+		if (info->band == NL80211_BAND_2GHZ) {
+			if (txrate->idx <= AR9170_TX_PHY_RATE_CCK_11M)
+				tmp |= cpu_to_le32(AR9170_TX_PHY_MOD_CCK);
+			else
+				tmp |= cpu_to_le32(AR9170_TX_PHY_MOD_OFDM);
+		} else {
+			tmp |= cpu_to_le32(AR9170_TX_PHY_MOD_OFDM);
+		}
+
+		/*
+		 * short preamble seems to be broken too.
+		 *
+		 * if (txrate->flags & IEEE80211_TX_RC_USE_SHORT_PREAMBLE)
+		 *	tmp |= cpu_to_le32(AR9170_TX_PHY_SHORT_PREAMBLE);
+		 */
+	}
+	carl9170_tx_rate_tpc_chains(ar, info, txrate,
+				    &phyrate, &power, &chains);
+
+	tmp |= cpu_to_le32(SET_CONSTVAL(AR9170_TX_PHY_MCS, phyrate));
+	tmp |= cpu_to_le32(SET_CONSTVAL(AR9170_TX_PHY_TX_PWR, power));
+	tmp |= cpu_to_le32(SET_CONSTVAL(AR9170_TX_PHY_TXCHAIN, chains));
+	return tmp;
+}
+
+static bool carl9170_tx_rts_check(struct ar9170 *ar,
+				  struct ieee80211_tx_rate *rate,
+				  bool ampdu, bool multi)
+{
+	switch (ar->erp_mode) {
+	case CARL9170_ERP_AUTO:
+		if (ampdu)
+			break;
+		fallthrough;
+
+	case CARL9170_ERP_MAC80211:
+		if (!(rate->flags & IEEE80211_TX_RC_USE_RTS_CTS))
+			break;
+		fallthrough;
+
+	case CARL9170_ERP_RTS:
+		if (likely(!multi))
+			return true;
+		break;
+
+	default:
+		break;
+	}
+
+	return false;
+}
+
+static bool carl9170_tx_cts_check(struct ar9170 *ar,
+				  struct ieee80211_tx_rate *rate)
+{
+	switch (ar->erp_mode) {
+	case CARL9170_ERP_AUTO:
+	case CARL9170_ERP_MAC80211:
+		if (!(rate->flags & IEEE80211_TX_RC_USE_CTS_PROTECT))
+			break;
+		fallthrough;
+
+	case CARL9170_ERP_CTS:
+		return true;
+
+	default:
+		break;
+	}
+
+	return false;
+}
+
+static void carl9170_tx_get_rates(struct ar9170 *ar,
+				  struct ieee80211_vif *vif,
+				  struct ieee80211_sta *sta,
+				  struct sk_buff *skb)
+{
+	struct ieee80211_tx_info *info;
+
+	BUILD_BUG_ON(IEEE80211_TX_MAX_RATES < CARL9170_TX_MAX_RATES);
+	BUILD_BUG_ON(IEEE80211_TX_MAX_RATES > IEEE80211_TX_RATE_TABLE_SIZE);
+
+	info = IEEE80211_SKB_CB(skb);
+
+	ieee80211_get_tx_rates(vif, sta, skb,
+			       info->control.rates,
+			       IEEE80211_TX_MAX_RATES);
+}
+
+static void carl9170_tx_apply_rateset(struct ar9170 *ar,
+				      struct ieee80211_tx_info *sinfo,
+				      struct sk_buff *skb)
+{
+	struct ieee80211_tx_rate *txrate;
+	struct ieee80211_tx_info *info;
+	struct _carl9170_tx_superframe *txc = (void *) skb->data;
+	int i;
+	bool ampdu;
+	bool no_ack;
+
+	info = IEEE80211_SKB_CB(skb);
+	ampdu = !!(info->flags & IEEE80211_TX_CTL_AMPDU);
+	no_ack = !!(info->flags & IEEE80211_TX_CTL_NO_ACK);
+
+	/* Set the rate control probe flag for all (sub-) frames.
+	 * This is because the TX_STATS_AMPDU flag is only set on
+	 * the last frame, so it has to be inherited.
+	 */
+	info->flags |= (sinfo->flags & IEEE80211_TX_CTL_RATE_CTRL_PROBE);
+
+	/* NOTE: For the first rate, the ERP & AMPDU flags are directly
+	 * taken from mac_control. For all fallback rate, the firmware
+	 * updates the mac_control flags from the rate info field.
+	 */
+	for (i = 0; i < CARL9170_TX_MAX_RATES; i++) {
+		__le32 phy_set;
+
+		txrate = &sinfo->control.rates[i];
+		if (txrate->idx < 0)
+			break;
+
+		phy_set = carl9170_tx_physet(ar, info, txrate);
+		if (i == 0) {
+			__le16 mac_tmp = cpu_to_le16(0);
+
+			/* first rate - part of the hw's frame header */
+			txc->f.phy_control = phy_set;
+
+			if (ampdu && txrate->flags & IEEE80211_TX_RC_MCS)
+				mac_tmp |= cpu_to_le16(AR9170_TX_MAC_AGGR);
+
+			if (carl9170_tx_rts_check(ar, txrate, ampdu, no_ack))
+				mac_tmp |= cpu_to_le16(AR9170_TX_MAC_PROT_RTS);
+			else if (carl9170_tx_cts_check(ar, txrate))
+				mac_tmp |= cpu_to_le16(AR9170_TX_MAC_PROT_CTS);
+
+			txc->f.mac_control |= mac_tmp;
+		} else {
+			/* fallback rates are stored in the firmware's
+			 * retry rate set array.
+			 */
+			txc->s.rr[i - 1] = phy_set;
+		}
+
+		SET_VAL(CARL9170_TX_SUPER_RI_TRIES, txc->s.ri[i],
+			txrate->count);
+
+		if (carl9170_tx_rts_check(ar, txrate, ampdu, no_ack))
+			txc->s.ri[i] |= (AR9170_TX_MAC_PROT_RTS <<
+				CARL9170_TX_SUPER_RI_ERP_PROT_S);
+		else if (carl9170_tx_cts_check(ar, txrate))
+			txc->s.ri[i] |= (AR9170_TX_MAC_PROT_CTS <<
+				CARL9170_TX_SUPER_RI_ERP_PROT_S);
+
+		if (ampdu && (txrate->flags & IEEE80211_TX_RC_MCS))
+			txc->s.ri[i] |= CARL9170_TX_SUPER_RI_AMPDU;
+	}
+}
+
+static int carl9170_tx_prepare(struct ar9170 *ar,
+			       struct ieee80211_sta *sta,
+			       struct sk_buff *skb)
+{
+	struct ieee80211_hdr *hdr;
+	struct _carl9170_tx_superframe *txc;
+	struct carl9170_vif_info *cvif;
+	struct ieee80211_tx_info *info;
+	struct carl9170_tx_info *arinfo;
+	unsigned int hw_queue;
+	__le16 mac_tmp;
+	u16 len;
+
+	BUILD_BUG_ON(sizeof(*arinfo) > sizeof(info->rate_driver_data));
+	BUILD_BUG_ON(sizeof(struct _carl9170_tx_superdesc) !=
+		     CARL9170_TX_SUPERDESC_LEN);
+
+	BUILD_BUG_ON(sizeof(struct _ar9170_tx_hwdesc) !=
+		     AR9170_TX_HWDESC_LEN);
+
+	BUILD_BUG_ON(AR9170_MAX_VIRTUAL_MAC >
+		((CARL9170_TX_SUPER_MISC_VIF_ID >>
+		 CARL9170_TX_SUPER_MISC_VIF_ID_S) + 1));
+
+	hw_queue = ar9170_qmap(carl9170_get_queue(ar, skb));
+
+	hdr = (void *)skb->data;
+	info = IEEE80211_SKB_CB(skb);
+	len = skb->len;
+
+	/*
+	 * Note: If the frame was sent through a monitor interface,
+	 * the ieee80211_vif pointer can be NULL.
+	 */
+	if (likely(info->control.vif))
+		cvif = (void *) info->control.vif->drv_priv;
+	else
+		cvif = NULL;
+
+	txc = skb_push(skb, sizeof(*txc));
+	memset(txc, 0, sizeof(*txc));
+
+	SET_VAL(CARL9170_TX_SUPER_MISC_QUEUE, txc->s.misc, hw_queue);
+
+	if (likely(cvif))
+		SET_VAL(CARL9170_TX_SUPER_MISC_VIF_ID, txc->s.misc, cvif->id);
+
+	if (unlikely(info->flags & IEEE80211_TX_CTL_SEND_AFTER_DTIM))
+		txc->s.misc |= CARL9170_TX_SUPER_MISC_CAB;
+
+	if (unlikely(info->flags & IEEE80211_TX_CTL_ASSIGN_SEQ))
+		txc->s.misc |= CARL9170_TX_SUPER_MISC_ASSIGN_SEQ;
+
+	if (unlikely(ieee80211_is_probe_resp(hdr->frame_control)))
+		txc->s.misc |= CARL9170_TX_SUPER_MISC_FILL_IN_TSF;
+
+	mac_tmp = cpu_to_le16(AR9170_TX_MAC_HW_DURATION |
+			      AR9170_TX_MAC_BACKOFF);
+	mac_tmp |= cpu_to_le16((hw_queue << AR9170_TX_MAC_QOS_S) &
+			       AR9170_TX_MAC_QOS);
+
+	if (unlikely(info->flags & IEEE80211_TX_CTL_NO_ACK))
+		mac_tmp |= cpu_to_le16(AR9170_TX_MAC_NO_ACK);
+
+	if (info->control.hw_key) {
+		len += info->control.hw_key->icv_len;
+
+		switch (info->control.hw_key->cipher) {
+		case WLAN_CIPHER_SUITE_WEP40:
+		case WLAN_CIPHER_SUITE_WEP104:
+		case WLAN_CIPHER_SUITE_TKIP:
+			mac_tmp |= cpu_to_le16(AR9170_TX_MAC_ENCR_RC4);
+			break;
+		case WLAN_CIPHER_SUITE_CCMP:
+			mac_tmp |= cpu_to_le16(AR9170_TX_MAC_ENCR_AES);
+			break;
+		default:
+			WARN_ON(1);
+			goto err_out;
+		}
+	}
+
+	if (info->flags & IEEE80211_TX_CTL_AMPDU) {
+		unsigned int density, factor;
+
+		if (unlikely(!sta || !cvif))
+			goto err_out;
+
+		factor = min_t(unsigned int, 1u,
+			       sta->deflink.ht_cap.ampdu_factor);
+		density = sta->deflink.ht_cap.ampdu_density;
+
+		if (density) {
+			/*
+			 * Watch out!
+			 *
+			 * Otus uses slightly different density values than
+			 * those from the 802.11n spec.
+			 */
+
+			density = max_t(unsigned int, density + 1, 7u);
+		}
+
+		SET_VAL(CARL9170_TX_SUPER_AMPDU_DENSITY,
+			txc->s.ampdu_settings, density);
+
+		SET_VAL(CARL9170_TX_SUPER_AMPDU_FACTOR,
+			txc->s.ampdu_settings, factor);
+	}
+
+	txc->s.len = cpu_to_le16(skb->len);
+	txc->f.length = cpu_to_le16(len + FCS_LEN);
+	txc->f.mac_control = mac_tmp;
+
+	arinfo = (void *)info->rate_driver_data;
+	arinfo->timeout = jiffies;
+	arinfo->ar = ar;
+	kref_init(&arinfo->ref);
+	return 0;
+
+err_out:
+	skb_pull(skb, sizeof(*txc));
+	return -EINVAL;
+}
+
+static void carl9170_set_immba(struct ar9170 *ar, struct sk_buff *skb)
+{
+	struct _carl9170_tx_superframe *super;
+
+	super = (void *) skb->data;
+	super->f.mac_control |= cpu_to_le16(AR9170_TX_MAC_IMM_BA);
+}
+
+static void carl9170_set_ampdu_params(struct ar9170 *ar, struct sk_buff *skb)
+{
+	struct _carl9170_tx_superframe *super;
+	int tmp;
+
+	super = (void *) skb->data;
+
+	tmp = (super->s.ampdu_settings & CARL9170_TX_SUPER_AMPDU_DENSITY) <<
+		CARL9170_TX_SUPER_AMPDU_DENSITY_S;
+
+	/*
+	 * If you haven't noticed carl9170_tx_prepare has already filled
+	 * in all ampdu spacing & factor parameters.
+	 * Now it's the time to check whenever the settings have to be
+	 * updated by the firmware, or if everything is still the same.
+	 *
+	 * There's no sane way to handle different density values with
+	 * this hardware, so we may as well just do the compare in the
+	 * driver.
+	 */
+
+	if (tmp != ar->current_density) {
+		ar->current_density = tmp;
+		super->s.ampdu_settings |=
+			CARL9170_TX_SUPER_AMPDU_COMMIT_DENSITY;
+	}
+
+	tmp = (super->s.ampdu_settings & CARL9170_TX_SUPER_AMPDU_FACTOR) <<
+		CARL9170_TX_SUPER_AMPDU_FACTOR_S;
+
+	if (tmp != ar->current_factor) {
+		ar->current_factor = tmp;
+		super->s.ampdu_settings |=
+			CARL9170_TX_SUPER_AMPDU_COMMIT_FACTOR;
+	}
+}
+
+static void carl9170_tx_ampdu(struct ar9170 *ar)
+{
+	struct sk_buff_head agg;
+	struct carl9170_sta_tid *tid_info;
+	struct sk_buff *skb, *first;
+	struct ieee80211_tx_info *tx_info_first;
+	unsigned int i = 0, done_ampdus = 0;
+	u16 seq, queue, tmpssn;
+
+	atomic_inc(&ar->tx_ampdu_scheduler);
+	ar->tx_ampdu_schedule = false;
+
+	if (atomic_read(&ar->tx_ampdu_upload))
+		return;
+
+	if (!ar->tx_ampdu_list_len)
+		return;
+
+	__skb_queue_head_init(&agg);
+
+	rcu_read_lock();
+	tid_info = rcu_dereference(ar->tx_ampdu_iter);
+	if (WARN_ON_ONCE(!tid_info)) {
+		rcu_read_unlock();
+		return;
+	}
+
+retry:
+	list_for_each_entry_continue_rcu(tid_info, &ar->tx_ampdu_list, list) {
+		i++;
+
+		if (tid_info->state < CARL9170_TID_STATE_PROGRESS)
+			continue;
+
+		queue = TID_TO_WME_AC(tid_info->tid);
+
+		spin_lock_bh(&tid_info->lock);
+		if (tid_info->state != CARL9170_TID_STATE_XMIT)
+			goto processed;
+
+		tid_info->counter++;
+		first = skb_peek(&tid_info->queue);
+		tmpssn = carl9170_get_seq(first);
+		seq = tid_info->snx;
+
+		if (unlikely(tmpssn != seq)) {
+			tid_info->state = CARL9170_TID_STATE_IDLE;
+
+			goto processed;
+		}
+
+		tx_info_first = NULL;
+		while ((skb = skb_peek(&tid_info->queue))) {
+			/* strict 0, 1, ..., n - 1, n frame sequence order */
+			if (unlikely(carl9170_get_seq(skb) != seq))
+				break;
+
+			/* don't upload more than AMPDU FACTOR allows. */
+			if (unlikely(SEQ_DIFF(tid_info->snx, tid_info->bsn) >=
+			    (tid_info->max - 1)))
+				break;
+
+			if (!tx_info_first) {
+				carl9170_tx_get_rates(ar, tid_info->vif,
+						      tid_info->sta, first);
+				tx_info_first = IEEE80211_SKB_CB(first);
+			}
+
+			carl9170_tx_apply_rateset(ar, tx_info_first, skb);
+
+			atomic_inc(&ar->tx_ampdu_upload);
+			tid_info->snx = seq = SEQ_NEXT(seq);
+			__skb_unlink(skb, &tid_info->queue);
+
+			__skb_queue_tail(&agg, skb);
+
+			if (skb_queue_len(&agg) >= CARL9170_NUM_TX_AGG_MAX)
+				break;
+		}
+
+		if (skb_queue_empty(&tid_info->queue) ||
+		    carl9170_get_seq(skb_peek(&tid_info->queue)) !=
+		    tid_info->snx) {
+			/* stop TID, if A-MPDU frames are still missing,
+			 * or whenever the queue is empty.
+			 */
+
+			tid_info->state = CARL9170_TID_STATE_IDLE;
+		}
+		done_ampdus++;
+
+processed:
+		spin_unlock_bh(&tid_info->lock);
+
+		if (skb_queue_empty(&agg))
+			continue;
+
+		/* apply ampdu spacing & factor settings */
+		carl9170_set_ampdu_params(ar, skb_peek(&agg));
+
+		/* set aggregation push bit */
+		carl9170_set_immba(ar, skb_peek_tail(&agg));
+
+		spin_lock_bh(&ar->tx_pending[queue].lock);
+		skb_queue_splice_tail_init(&agg, &ar->tx_pending[queue]);
+		spin_unlock_bh(&ar->tx_pending[queue].lock);
+		ar->tx_schedule = true;
+	}
+	if ((done_ampdus++ == 0) && (i++ == 0))
+		goto retry;
+
+	rcu_assign_pointer(ar->tx_ampdu_iter, tid_info);
+	rcu_read_unlock();
+}
+
+static struct sk_buff *carl9170_tx_pick_skb(struct ar9170 *ar,
+					    struct sk_buff_head *queue)
+{
+	struct sk_buff *skb;
+	struct ieee80211_tx_info *info;
+	struct carl9170_tx_info *arinfo;
+
+	BUILD_BUG_ON(sizeof(*arinfo) > sizeof(info->rate_driver_data));
+
+	spin_lock_bh(&queue->lock);
+	skb = skb_peek(queue);
+	if (unlikely(!skb))
+		goto err_unlock;
+
+	if (carl9170_alloc_dev_space(ar, skb))
+		goto err_unlock;
+
+	__skb_unlink(skb, queue);
+	spin_unlock_bh(&queue->lock);
+
+	info = IEEE80211_SKB_CB(skb);
+	arinfo = (void *) info->rate_driver_data;
+
+	arinfo->timeout = jiffies;
+	return skb;
+
+err_unlock:
+	spin_unlock_bh(&queue->lock);
+	return NULL;
+}
+
+void carl9170_tx_drop(struct ar9170 *ar, struct sk_buff *skb)
+{
+	struct _carl9170_tx_superframe *super;
+	uint8_t q = 0;
+
+	ar->tx_dropped++;
+
+	super = (void *)skb->data;
+	SET_VAL(CARL9170_TX_SUPER_MISC_QUEUE, q,
+		ar9170_qmap(carl9170_get_queue(ar, skb)));
+	__carl9170_tx_process_status(ar, super->s.cookie, q);
+}
+
+static bool carl9170_tx_ps_drop(struct ar9170 *ar, struct sk_buff *skb)
+{
+	struct ieee80211_sta *sta;
+	struct carl9170_sta_info *sta_info;
+	struct ieee80211_tx_info *tx_info;
+
+	rcu_read_lock();
+	sta = __carl9170_get_tx_sta(ar, skb);
+	if (!sta)
+		goto out_rcu;
+
+	sta_info = (void *) sta->drv_priv;
+	tx_info = IEEE80211_SKB_CB(skb);
+
+	if (unlikely(sta_info->sleeping) &&
+	    !(tx_info->flags & (IEEE80211_TX_CTL_NO_PS_BUFFER |
+				IEEE80211_TX_CTL_CLEAR_PS_FILT))) {
+		rcu_read_unlock();
+
+		if (tx_info->flags & IEEE80211_TX_CTL_AMPDU)
+			atomic_dec(&ar->tx_ampdu_upload);
+
+		tx_info->flags |= IEEE80211_TX_STAT_TX_FILTERED;
+		carl9170_release_dev_space(ar, skb);
+		carl9170_tx_status(ar, skb, false);
+		return true;
+	}
+
+out_rcu:
+	rcu_read_unlock();
+	return false;
+}
+
+static void carl9170_bar_check(struct ar9170 *ar, struct sk_buff *skb)
+{
+	struct _carl9170_tx_superframe *super = (void *) skb->data;
+	struct ieee80211_bar *bar = (void *) super->frame_data;
+
+	if (unlikely(ieee80211_is_back_req(bar->frame_control)) &&
+	    skb->len >= sizeof(struct ieee80211_bar)) {
+		struct carl9170_bar_list_entry *entry;
+		unsigned int queue = skb_get_queue_mapping(skb);
+
+		entry = kmalloc(sizeof(*entry), GFP_ATOMIC);
+		if (!WARN_ON_ONCE(!entry)) {
+			entry->skb = skb;
+			spin_lock_bh(&ar->bar_list_lock[queue]);
+			list_add_tail_rcu(&entry->list, &ar->bar_list[queue]);
+			spin_unlock_bh(&ar->bar_list_lock[queue]);
+		}
+	}
+}
+
+static void carl9170_tx(struct ar9170 *ar)
+{
+	struct sk_buff *skb;
+	unsigned int i, q;
+	bool schedule_garbagecollector = false;
+
+	ar->tx_schedule = false;
+
+	if (unlikely(!IS_STARTED(ar)))
+		return;
+
+	carl9170_usb_handle_tx_err(ar);
+
+	for (i = 0; i < ar->hw->queues; i++) {
+		while (!skb_queue_empty(&ar->tx_pending[i])) {
+			skb = carl9170_tx_pick_skb(ar, &ar->tx_pending[i]);
+			if (unlikely(!skb))
+				break;
+
+			if (unlikely(carl9170_tx_ps_drop(ar, skb)))
+				continue;
+
+			carl9170_bar_check(ar, skb);
+
+			atomic_inc(&ar->tx_total_pending);
+
+			q = __carl9170_get_queue(ar, i);
+			/*
+			 * NB: tx_status[i] vs. tx_status[q],
+			 * TODO: Move into pick_skb or alloc_dev_space.
+			 */
+			skb_queue_tail(&ar->tx_status[q], skb);
+
+			/*
+			 * increase ref count to "2".
+			 * Ref counting is the easiest way to solve the
+			 * race between the urb's completion routine:
+			 *	carl9170_tx_callback
+			 * and wlan tx status functions:
+			 *	carl9170_tx_status/janitor.
+			 */
+			carl9170_tx_get_skb(skb);
+
+			carl9170_usb_tx(ar, skb);
+			schedule_garbagecollector = true;
+		}
+	}
+
+	if (!schedule_garbagecollector)
+		return;
+
+	ieee80211_queue_delayed_work(ar->hw, &ar->tx_janitor,
+		msecs_to_jiffies(CARL9170_TX_TIMEOUT));
+}
+
+static bool carl9170_tx_ampdu_queue(struct ar9170 *ar,
+	struct ieee80211_sta *sta, struct sk_buff *skb,
+	struct ieee80211_tx_info *txinfo)
+{
+	struct carl9170_sta_info *sta_info;
+	struct carl9170_sta_tid *agg;
+	struct sk_buff *iter;
+	u16 tid, seq, qseq, off;
+	bool run = false;
+
+	tid = carl9170_get_tid(skb);
+	seq = carl9170_get_seq(skb);
+	sta_info = (void *) sta->drv_priv;
+
+	rcu_read_lock();
+	agg = rcu_dereference(sta_info->agg[tid]);
+
+	if (!agg)
+		goto err_unlock_rcu;
+
+	spin_lock_bh(&agg->lock);
+	if (unlikely(agg->state < CARL9170_TID_STATE_IDLE))
+		goto err_unlock;
+
+	/* check if sequence is within the BA window */
+	if (unlikely(!BAW_WITHIN(agg->bsn, CARL9170_BAW_BITS, seq)))
+		goto err_unlock;
+
+	if (WARN_ON_ONCE(!BAW_WITHIN(agg->snx, CARL9170_BAW_BITS, seq)))
+		goto err_unlock;
+
+	off = SEQ_DIFF(seq, agg->bsn);
+	if (WARN_ON_ONCE(test_and_set_bit(off, agg->bitmap)))
+		goto err_unlock;
+
+	if (likely(BAW_WITHIN(agg->hsn, CARL9170_BAW_BITS, seq))) {
+		__skb_queue_tail(&agg->queue, skb);
+		agg->hsn = seq;
+		goto queued;
+	}
+
+	skb_queue_reverse_walk(&agg->queue, iter) {
+		qseq = carl9170_get_seq(iter);
+
+		if (BAW_WITHIN(qseq, CARL9170_BAW_BITS, seq)) {
+			__skb_queue_after(&agg->queue, iter, skb);
+			goto queued;
+		}
+	}
+
+	__skb_queue_head(&agg->queue, skb);
+queued:
+
+	if (unlikely(agg->state != CARL9170_TID_STATE_XMIT)) {
+		if (agg->snx == carl9170_get_seq(skb_peek(&agg->queue))) {
+			agg->state = CARL9170_TID_STATE_XMIT;
+			run = true;
+		}
+	}
+
+	spin_unlock_bh(&agg->lock);
+	rcu_read_unlock();
+
+	return run;
+
+err_unlock:
+	spin_unlock_bh(&agg->lock);
+
+err_unlock_rcu:
+	rcu_read_unlock();
+	txinfo->flags &= ~IEEE80211_TX_CTL_AMPDU;
+	carl9170_tx_status(ar, skb, false);
+	ar->tx_dropped++;
+	return false;
+}
+
+void carl9170_op_tx(struct ieee80211_hw *hw,
+		    struct ieee80211_tx_control *control,
+		    struct sk_buff *skb)
+{
+	struct ar9170 *ar = hw->priv;
+	struct ieee80211_tx_info *info;
+	struct ieee80211_sta *sta = control->sta;
+	struct ieee80211_vif *vif;
+	bool run;
+
+	if (unlikely(!IS_STARTED(ar)))
+		goto err_free;
+
+	info = IEEE80211_SKB_CB(skb);
+	vif = info->control.vif;
+
+	if (unlikely(carl9170_tx_prepare(ar, sta, skb)))
+		goto err_free;
+
+	carl9170_tx_accounting(ar, skb);
+	/*
+	 * from now on, one has to use carl9170_tx_status to free
+	 * all ressouces which are associated with the frame.
+	 */
+
+	if (sta) {
+		struct carl9170_sta_info *stai = (void *) sta->drv_priv;
+		atomic_inc(&stai->pending_frames);
+	}
+
+	if (info->flags & IEEE80211_TX_CTL_AMPDU) {
+		/* to static code analyzers and reviewers:
+		 * mac80211 guarantees that a valid "sta"
+		 * reference is present, if a frame is to
+		 * be part of an ampdu. Hence any extra
+		 * sta == NULL checks are redundant in this
+		 * special case.
+		 */
+		run = carl9170_tx_ampdu_queue(ar, sta, skb, info);
+		if (run)
+			carl9170_tx_ampdu(ar);
+
+	} else {
+		unsigned int queue = skb_get_queue_mapping(skb);
+
+		carl9170_tx_get_rates(ar, vif, sta, skb);
+		carl9170_tx_apply_rateset(ar, info, skb);
+		skb_queue_tail(&ar->tx_pending[queue], skb);
+	}
+
+	carl9170_tx(ar);
+	return;
+
+err_free:
+	ar->tx_dropped++;
+	ieee80211_free_txskb(ar->hw, skb);
+}
+
+void carl9170_tx_scheduler(struct ar9170 *ar)
+{
+
+	if (ar->tx_ampdu_schedule)
+		carl9170_tx_ampdu(ar);
+
+	if (ar->tx_schedule)
+		carl9170_tx(ar);
+}
+
+/* caller has to take rcu_read_lock */
+static struct carl9170_vif_info *carl9170_pick_beaconing_vif(struct ar9170 *ar)
+{
+	struct carl9170_vif_info *cvif;
+	int i = 1;
+
+	/* The AR9170 hardware has no fancy beacon queue or some
+	 * other scheduling mechanism. So, the driver has to make
+	 * due by setting the two beacon timers (pretbtt and tbtt)
+	 * once and then swapping the beacon address in the HW's
+	 * register file each time the pretbtt fires.
+	 */
+
+	cvif = rcu_dereference(ar->beacon_iter);
+	if (ar->vifs > 0 && cvif) {
+		do {
+			list_for_each_entry_continue_rcu(cvif, &ar->vif_list,
+							 list) {
+				if (cvif->active && cvif->enable_beacon)
+					goto out;
+			}
+		} while (ar->beacon_enabled && i--);
+
+		/* no entry found in list */
+		return NULL;
+	}
+
+out:
+	RCU_INIT_POINTER(ar->beacon_iter, cvif);
+	return cvif;
+}
+
+static bool carl9170_tx_beacon_physet(struct ar9170 *ar, struct sk_buff *skb,
+				      u32 *ht1, u32 *plcp)
+{
+	struct ieee80211_tx_info *txinfo;
+	struct ieee80211_tx_rate *rate;
+	unsigned int power, chains;
+	bool ht_rate;
+
+	txinfo = IEEE80211_SKB_CB(skb);
+	rate = &txinfo->control.rates[0];
+	ht_rate = !!(txinfo->control.rates[0].flags & IEEE80211_TX_RC_MCS);
+	carl9170_tx_rate_tpc_chains(ar, txinfo, rate, plcp, &power, &chains);
+
+	*ht1 = AR9170_MAC_BCN_HT1_TX_ANT0;
+	if (chains == AR9170_TX_PHY_TXCHAIN_2)
+		*ht1 |= AR9170_MAC_BCN_HT1_TX_ANT1;
+	SET_VAL(AR9170_MAC_BCN_HT1_PWR_CTRL, *ht1, 7);
+	SET_VAL(AR9170_MAC_BCN_HT1_TPC, *ht1, power);
+	SET_VAL(AR9170_MAC_BCN_HT1_CHAIN_MASK, *ht1, chains);
+
+	if (ht_rate) {
+		*ht1 |= AR9170_MAC_BCN_HT1_HT_EN;
+		if (rate->flags & IEEE80211_TX_RC_SHORT_GI)
+			*plcp |= AR9170_MAC_BCN_HT2_SGI;
+
+		if (rate->flags & IEEE80211_TX_RC_40_MHZ_WIDTH) {
+			*ht1 |= AR9170_MAC_BCN_HT1_BWC_40M_SHARED;
+			*plcp |= AR9170_MAC_BCN_HT2_BW40;
+		} else if (rate->flags & IEEE80211_TX_RC_DUP_DATA) {
+			*ht1 |= AR9170_MAC_BCN_HT1_BWC_40M_DUP;
+			*plcp |= AR9170_MAC_BCN_HT2_BW40;
+		}
+
+		SET_VAL(AR9170_MAC_BCN_HT2_LEN, *plcp, skb->len + FCS_LEN);
+	} else {
+		if (*plcp <= AR9170_TX_PHY_RATE_CCK_11M)
+			*plcp |= ((skb->len + FCS_LEN) << (3 + 16)) + 0x0400;
+		else
+			*plcp |= ((skb->len + FCS_LEN) << 16) + 0x0010;
+	}
+
+	return ht_rate;
+}
+
+int carl9170_update_beacon(struct ar9170 *ar, const bool submit)
+{
+	struct sk_buff *skb = NULL;
+	struct carl9170_vif_info *cvif;
+	__le32 *data, *old = NULL;
+	u32 word, ht1, plcp, off, addr, len;
+	int i = 0, err = 0;
+	bool ht_rate;
+
+	rcu_read_lock();
+	cvif = carl9170_pick_beaconing_vif(ar);
+	if (!cvif)
+		goto out_unlock;
+
+	skb = ieee80211_beacon_get_tim(ar->hw, carl9170_get_vif(cvif),
+				       NULL, NULL, 0);
+
+	if (!skb) {
+		err = -ENOMEM;
+		goto err_free;
+	}
+
+	spin_lock_bh(&ar->beacon_lock);
+	data = (__le32 *)skb->data;
+	if (cvif->beacon)
+		old = (__le32 *)cvif->beacon->data;
+
+	off = cvif->id * AR9170_MAC_BCN_LENGTH_MAX;
+	addr = ar->fw.beacon_addr + off;
+	len = roundup(skb->len + FCS_LEN, 4);
+
+	if ((off + len) > ar->fw.beacon_max_len) {
+		if (net_ratelimit()) {
+			wiphy_err(ar->hw->wiphy, "beacon does not "
+				  "fit into device memory!\n");
+		}
+		err = -EINVAL;
+		goto err_unlock;
+	}
+
+	if (len > AR9170_MAC_BCN_LENGTH_MAX) {
+		if (net_ratelimit()) {
+			wiphy_err(ar->hw->wiphy, "no support for beacons "
+				"bigger than %d (yours:%d).\n",
+				 AR9170_MAC_BCN_LENGTH_MAX, len);
+		}
+
+		err = -EMSGSIZE;
+		goto err_unlock;
+	}
+
+	ht_rate = carl9170_tx_beacon_physet(ar, skb, &ht1, &plcp);
+
+	carl9170_async_regwrite_begin(ar);
+	carl9170_async_regwrite(AR9170_MAC_REG_BCN_HT1, ht1);
+	if (ht_rate)
+		carl9170_async_regwrite(AR9170_MAC_REG_BCN_HT2, plcp);
+	else
+		carl9170_async_regwrite(AR9170_MAC_REG_BCN_PLCP, plcp);
+
+	for (i = 0; i < DIV_ROUND_UP(skb->len, 4); i++) {
+		/*
+		 * XXX: This accesses beyond skb data for up
+		 *	to the last 3 bytes!!
+		 */
+
+		if (old && (data[i] == old[i]))
+			continue;
+
+		word = le32_to_cpu(data[i]);
+		carl9170_async_regwrite(addr + 4 * i, word);
+	}
+	carl9170_async_regwrite_finish();
+
+	dev_kfree_skb_any(cvif->beacon);
+	cvif->beacon = NULL;
+
+	err = carl9170_async_regwrite_result();
+	if (!err)
+		cvif->beacon = skb;
+	spin_unlock_bh(&ar->beacon_lock);
+	if (err)
+		goto err_free;
+
+	if (submit) {
+		err = carl9170_bcn_ctrl(ar, cvif->id,
+					CARL9170_BCN_CTRL_CAB_TRIGGER,
+					addr, skb->len + FCS_LEN);
+
+		if (err)
+			goto err_free;
+	}
+out_unlock:
+	rcu_read_unlock();
+	return 0;
+
+err_unlock:
+	spin_unlock_bh(&ar->beacon_lock);
+
+err_free:
+	rcu_read_unlock();
+	dev_kfree_skb_any(skb);
+	return err;
+}