Adding upstream version 4.19.249.upstream/4.19.249

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

1 files changed, 736 insertions, 0 deletions

diff --git a/net/mac80211/rc80211_minstrel.c b/net/mac80211/rc80211_minstrel.c
new file mode 100644
index 000000000..1f3c420c0
--- /dev/null
+++ b/net/mac80211/rc80211_minstrel.c
@@ -0,0 +1,736 @@
+/*
+ * Copyright (C) 2008 Felix Fietkau <nbd@openwrt.org>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ * Based on minstrel.c:
+ *   Copyright (C) 2005-2007 Derek Smithies <derek@indranet.co.nz>
+ *   Sponsored by Indranet Technologies Ltd
+ *
+ * Based on sample.c:
+ *   Copyright (c) 2005 John Bicket
+ *   All rights reserved.
+ *
+ *   Redistribution and use in source and binary forms, with or without
+ *   modification, are permitted provided that the following conditions
+ *   are met:
+ *   1. Redistributions of source code must retain the above copyright
+ *      notice, this list of conditions and the following disclaimer,
+ *      without modification.
+ *   2. Redistributions in binary form must reproduce at minimum a disclaimer
+ *      similar to the "NO WARRANTY" disclaimer below ("Disclaimer") and any
+ *      redistribution must be conditioned upon including a substantially
+ *      similar Disclaimer requirement for further binary redistribution.
+ *   3. Neither the names of the above-listed copyright holders nor the names
+ *      of any contributors may be used to endorse or promote products derived
+ *      from this software without specific prior written permission.
+ *
+ *   Alternatively, this software may be distributed under the terms of the
+ *   GNU General Public License ("GPL") version 2 as published by the Free
+ *   Software Foundation.
+ *
+ *   NO WARRANTY
+ *   THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ *   ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ *   LIMITED TO, THE IMPLIED WARRANTIES OF NONINFRINGEMENT, MERCHANTIBILITY
+ *   AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL
+ *   THE COPYRIGHT HOLDERS OR CONTRIBUTORS BE LIABLE FOR SPECIAL, EXEMPLARY,
+ *   OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+ *   SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+ *   INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER
+ *   IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ *   ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF
+ *   THE POSSIBILITY OF SUCH DAMAGES.
+ */
+#include <linux/netdevice.h>
+#include <linux/types.h>
+#include <linux/skbuff.h>
+#include <linux/debugfs.h>
+#include <linux/random.h>
+#include <linux/ieee80211.h>
+#include <linux/slab.h>
+#include <net/mac80211.h>
+#include "rate.h"
+#include "rc80211_minstrel.h"
+
+#define SAMPLE_TBL(_mi, _idx, _col) \
+		_mi->sample_table[(_idx * SAMPLE_COLUMNS) + _col]
+
+/* convert mac80211 rate index to local array index */
+static inline int
+rix_to_ndx(struct minstrel_sta_info *mi, int rix)
+{
+	int i = rix;
+	for (i = rix; i >= 0; i--)
+		if (mi->r[i].rix == rix)
+			break;
+	return i;
+}
+
+/* return current EMWA throughput */
+int minstrel_get_tp_avg(struct minstrel_rate *mr, int prob_ewma)
+{
+	int usecs;
+
+	usecs = mr->perfect_tx_time;
+	if (!usecs)
+		usecs = 1000000;
+
+	/* reset thr. below 10% success */
+	if (mr->stats.prob_ewma < MINSTREL_FRAC(10, 100))
+		return 0;
+
+	if (prob_ewma > MINSTREL_FRAC(90, 100))
+		return MINSTREL_TRUNC(100000 * (MINSTREL_FRAC(90, 100) / usecs));
+	else
+		return MINSTREL_TRUNC(100000 * (prob_ewma / usecs));
+}
+
+/* find & sort topmost throughput rates */
+static inline void
+minstrel_sort_best_tp_rates(struct minstrel_sta_info *mi, int i, u8 *tp_list)
+{
+	int j;
+	struct minstrel_rate_stats *tmp_mrs;
+	struct minstrel_rate_stats *cur_mrs = &mi->r[i].stats;
+
+	for (j = MAX_THR_RATES; j > 0; --j) {
+		tmp_mrs = &mi->r[tp_list[j - 1]].stats;
+		if (minstrel_get_tp_avg(&mi->r[i], cur_mrs->prob_ewma) <=
+		    minstrel_get_tp_avg(&mi->r[tp_list[j - 1]], tmp_mrs->prob_ewma))
+			break;
+	}
+
+	if (j < MAX_THR_RATES - 1)
+		memmove(&tp_list[j + 1], &tp_list[j], MAX_THR_RATES - (j + 1));
+	if (j < MAX_THR_RATES)
+		tp_list[j] = i;
+}
+
+static void
+minstrel_set_rate(struct minstrel_sta_info *mi, struct ieee80211_sta_rates *ratetbl,
+		  int offset, int idx)
+{
+	struct minstrel_rate *r = &mi->r[idx];
+
+	ratetbl->rate[offset].idx = r->rix;
+	ratetbl->rate[offset].count = r->adjusted_retry_count;
+	ratetbl->rate[offset].count_cts = r->retry_count_cts;
+	ratetbl->rate[offset].count_rts = r->stats.retry_count_rtscts;
+}
+
+static void
+minstrel_update_rates(struct minstrel_priv *mp, struct minstrel_sta_info *mi)
+{
+	struct ieee80211_sta_rates *ratetbl;
+	int i = 0;
+
+	ratetbl = kzalloc(sizeof(*ratetbl), GFP_ATOMIC);
+	if (!ratetbl)
+		return;
+
+	/* Start with max_tp_rate */
+	minstrel_set_rate(mi, ratetbl, i++, mi->max_tp_rate[0]);
+
+	if (mp->hw->max_rates >= 3) {
+		/* At least 3 tx rates supported, use max_tp_rate2 next */
+		minstrel_set_rate(mi, ratetbl, i++, mi->max_tp_rate[1]);
+	}
+
+	if (mp->hw->max_rates >= 2) {
+		/* At least 2 tx rates supported, use max_prob_rate next */
+		minstrel_set_rate(mi, ratetbl, i++, mi->max_prob_rate);
+	}
+
+	/* Use lowest rate last */
+	ratetbl->rate[i].idx = mi->lowest_rix;
+	ratetbl->rate[i].count = mp->max_retry;
+	ratetbl->rate[i].count_cts = mp->max_retry;
+	ratetbl->rate[i].count_rts = mp->max_retry;
+
+	rate_control_set_rates(mp->hw, mi->sta, ratetbl);
+}
+
+/*
+* Recalculate statistics and counters of a given rate
+*/
+void
+minstrel_calc_rate_stats(struct minstrel_rate_stats *mrs)
+{
+	unsigned int cur_prob;
+
+	if (unlikely(mrs->attempts > 0)) {
+		mrs->sample_skipped = 0;
+		cur_prob = MINSTREL_FRAC(mrs->success, mrs->attempts);
+		if (unlikely(!mrs->att_hist)) {
+			mrs->prob_ewma = cur_prob;
+		} else {
+			/* update exponential weighted moving variance */
+			mrs->prob_ewmv = minstrel_ewmv(mrs->prob_ewmv,
+							cur_prob,
+							mrs->prob_ewma,
+							EWMA_LEVEL);
+
+			/*update exponential weighted moving avarage */
+			mrs->prob_ewma = minstrel_ewma(mrs->prob_ewma,
+						       cur_prob,
+						       EWMA_LEVEL);
+		}
+		mrs->att_hist += mrs->attempts;
+		mrs->succ_hist += mrs->success;
+	} else {
+		mrs->sample_skipped++;
+	}
+
+	mrs->last_success = mrs->success;
+	mrs->last_attempts = mrs->attempts;
+	mrs->success = 0;
+	mrs->attempts = 0;
+}
+
+static void
+minstrel_update_stats(struct minstrel_priv *mp, struct minstrel_sta_info *mi)
+{
+	u8 tmp_tp_rate[MAX_THR_RATES];
+	u8 tmp_prob_rate = 0;
+	int i, tmp_cur_tp, tmp_prob_tp;
+
+	for (i = 0; i < MAX_THR_RATES; i++)
+	    tmp_tp_rate[i] = 0;
+
+	for (i = 0; i < mi->n_rates; i++) {
+		struct minstrel_rate *mr = &mi->r[i];
+		struct minstrel_rate_stats *mrs = &mi->r[i].stats;
+		struct minstrel_rate_stats *tmp_mrs = &mi->r[tmp_prob_rate].stats;
+
+		/* Update statistics of success probability per rate */
+		minstrel_calc_rate_stats(mrs);
+
+		/* Sample less often below the 10% chance of success.
+		 * Sample less often above the 95% chance of success. */
+		if (mrs->prob_ewma > MINSTREL_FRAC(95, 100) ||
+		    mrs->prob_ewma < MINSTREL_FRAC(10, 100)) {
+			mr->adjusted_retry_count = mrs->retry_count >> 1;
+			if (mr->adjusted_retry_count > 2)
+				mr->adjusted_retry_count = 2;
+			mr->sample_limit = 4;
+		} else {
+			mr->sample_limit = -1;
+			mr->adjusted_retry_count = mrs->retry_count;
+		}
+		if (!mr->adjusted_retry_count)
+			mr->adjusted_retry_count = 2;
+
+		minstrel_sort_best_tp_rates(mi, i, tmp_tp_rate);
+
+		/* To determine the most robust rate (max_prob_rate) used at
+		 * 3rd mmr stage we distinct between two cases:
+		 * (1) if any success probabilitiy >= 95%, out of those rates
+		 * choose the maximum throughput rate as max_prob_rate
+		 * (2) if all success probabilities < 95%, the rate with
+		 * highest success probability is chosen as max_prob_rate */
+		if (mrs->prob_ewma >= MINSTREL_FRAC(95, 100)) {
+			tmp_cur_tp = minstrel_get_tp_avg(mr, mrs->prob_ewma);
+			tmp_prob_tp = minstrel_get_tp_avg(&mi->r[tmp_prob_rate],
+							  tmp_mrs->prob_ewma);
+			if (tmp_cur_tp >= tmp_prob_tp)
+				tmp_prob_rate = i;
+		} else {
+			if (mrs->prob_ewma >= tmp_mrs->prob_ewma)
+				tmp_prob_rate = i;
+		}
+	}
+
+	/* Assign the new rate set */
+	memcpy(mi->max_tp_rate, tmp_tp_rate, sizeof(mi->max_tp_rate));
+	mi->max_prob_rate = tmp_prob_rate;
+
+#ifdef CONFIG_MAC80211_DEBUGFS
+	/* use fixed index if set */
+	if (mp->fixed_rate_idx != -1) {
+		mi->max_tp_rate[0] = mp->fixed_rate_idx;
+		mi->max_tp_rate[1] = mp->fixed_rate_idx;
+		mi->max_prob_rate = mp->fixed_rate_idx;
+	}
+#endif
+
+	/* Reset update timer */
+	mi->last_stats_update = jiffies;
+
+	minstrel_update_rates(mp, mi);
+}
+
+static void
+minstrel_tx_status(void *priv, struct ieee80211_supported_band *sband,
+		   void *priv_sta, struct ieee80211_tx_status *st)
+{
+	struct ieee80211_tx_info *info = st->info;
+	struct minstrel_priv *mp = priv;
+	struct minstrel_sta_info *mi = priv_sta;
+	struct ieee80211_tx_rate *ar = info->status.rates;
+	int i, ndx;
+	int success;
+
+	success = !!(info->flags & IEEE80211_TX_STAT_ACK);
+
+	for (i = 0; i < IEEE80211_TX_MAX_RATES; i++) {
+		if (ar[i].idx < 0 || !ar[i].count)
+			break;
+
+		ndx = rix_to_ndx(mi, ar[i].idx);
+		if (ndx < 0)
+			continue;
+
+		mi->r[ndx].stats.attempts += ar[i].count;
+
+		if ((i != IEEE80211_TX_MAX_RATES - 1) && (ar[i + 1].idx < 0))
+			mi->r[ndx].stats.success += success;
+	}
+
+	if (time_after(jiffies, mi->last_stats_update +
+				(mp->update_interval * HZ) / 1000))
+		minstrel_update_stats(mp, mi);
+}
+
+
+static inline unsigned int
+minstrel_get_retry_count(struct minstrel_rate *mr,
+			 struct ieee80211_tx_info *info)
+{
+	u8 retry = mr->adjusted_retry_count;
+
+	if (info->control.use_rts)
+		retry = max_t(u8, 2, min(mr->stats.retry_count_rtscts, retry));
+	else if (info->control.use_cts_prot)
+		retry = max_t(u8, 2, min(mr->retry_count_cts, retry));
+	return retry;
+}
+
+
+static int
+minstrel_get_next_sample(struct minstrel_sta_info *mi)
+{
+	unsigned int sample_ndx;
+	sample_ndx = SAMPLE_TBL(mi, mi->sample_row, mi->sample_column);
+	mi->sample_row++;
+	if ((int) mi->sample_row >= mi->n_rates) {
+		mi->sample_row = 0;
+		mi->sample_column++;
+		if (mi->sample_column >= SAMPLE_COLUMNS)
+			mi->sample_column = 0;
+	}
+	return sample_ndx;
+}
+
+static void
+minstrel_get_rate(void *priv, struct ieee80211_sta *sta,
+		  void *priv_sta, struct ieee80211_tx_rate_control *txrc)
+{
+	struct sk_buff *skb = txrc->skb;
+	struct ieee80211_tx_info *info = IEEE80211_SKB_CB(skb);
+	struct minstrel_sta_info *mi = priv_sta;
+	struct minstrel_priv *mp = priv;
+	struct ieee80211_tx_rate *rate = &info->control.rates[0];
+	struct minstrel_rate *msr, *mr;
+	unsigned int ndx;
+	bool mrr_capable;
+	bool prev_sample;
+	int delta;
+	int sampling_ratio;
+
+	/* management/no-ack frames do not use rate control */
+	if (rate_control_send_low(sta, priv_sta, txrc))
+		return;
+
+	/* check multi-rate-retry capabilities & adjust lookaround_rate */
+	mrr_capable = mp->has_mrr &&
+		      !txrc->rts &&
+		      !txrc->bss_conf->use_cts_prot;
+	if (mrr_capable)
+		sampling_ratio = mp->lookaround_rate_mrr;
+	else
+		sampling_ratio = mp->lookaround_rate;
+
+	/* increase sum packet counter */
+	mi->total_packets++;
+
+#ifdef CONFIG_MAC80211_DEBUGFS
+	if (mp->fixed_rate_idx != -1)
+		return;
+#endif
+
+	/* Don't use EAPOL frames for sampling on non-mrr hw */
+	if (mp->hw->max_rates == 1 &&
+	    (info->control.flags & IEEE80211_TX_CTRL_PORT_CTRL_PROTO))
+		return;
+
+	delta = (mi->total_packets * sampling_ratio / 100) -
+			mi->sample_packets;
+
+	/* delta < 0: no sampling required */
+	prev_sample = mi->prev_sample;
+	mi->prev_sample = false;
+	if (delta < 0 || (!mrr_capable && prev_sample))
+		return;
+
+	if (mi->total_packets >= 10000) {
+		mi->sample_packets = 0;
+		mi->total_packets = 0;
+	} else if (delta > mi->n_rates * 2) {
+		/* With multi-rate retry, not every planned sample
+		 * attempt actually gets used, due to the way the retry
+		 * chain is set up - [max_tp,sample,prob,lowest] for
+		 * sample_rate < max_tp.
+		 *
+		 * If there's too much sampling backlog and the link
+		 * starts getting worse, minstrel would start bursting
+		 * out lots of sampling frames, which would result
+		 * in a large throughput loss. */
+		mi->sample_packets += (delta - mi->n_rates * 2);
+	}
+
+	/* get next random rate sample */
+	ndx = minstrel_get_next_sample(mi);
+	msr = &mi->r[ndx];
+	mr = &mi->r[mi->max_tp_rate[0]];
+
+	/* Decide if direct ( 1st mrr stage) or indirect (2nd mrr stage)
+	 * rate sampling method should be used.
+	 * Respect such rates that are not sampled for 20 interations.
+	 */
+	if (msr->perfect_tx_time < mr->perfect_tx_time ||
+	    msr->stats.sample_skipped >= 20) {
+		if (!msr->sample_limit)
+			return;
+
+		mi->sample_packets++;
+		if (msr->sample_limit > 0)
+			msr->sample_limit--;
+	}
+
+	/* If we're not using MRR and the sampling rate already
+	 * has a probability of >95%, we shouldn't be attempting
+	 * to use it, as this only wastes precious airtime */
+	if (!mrr_capable &&
+	   (mi->r[ndx].stats.prob_ewma > MINSTREL_FRAC(95, 100)))
+		return;
+
+	mi->prev_sample = true;
+
+	rate->idx = mi->r[ndx].rix;
+	rate->count = minstrel_get_retry_count(&mi->r[ndx], info);
+	info->flags |= IEEE80211_TX_CTL_RATE_CTRL_PROBE;
+}
+
+
+static void
+calc_rate_durations(enum nl80211_band band,
+		    struct minstrel_rate *d,
+		    struct ieee80211_rate *rate,
+		    struct cfg80211_chan_def *chandef)
+{
+	int erp = !!(rate->flags & IEEE80211_RATE_ERP_G);
+	int shift = ieee80211_chandef_get_shift(chandef);
+
+	d->perfect_tx_time = ieee80211_frame_duration(band, 1200,
+			DIV_ROUND_UP(rate->bitrate, 1 << shift), erp, 1,
+			shift);
+	d->ack_time = ieee80211_frame_duration(band, 10,
+			DIV_ROUND_UP(rate->bitrate, 1 << shift), erp, 1,
+			shift);
+}
+
+static void
+init_sample_table(struct minstrel_sta_info *mi)
+{
+	unsigned int i, col, new_idx;
+	u8 rnd[8];
+
+	mi->sample_column = 0;
+	mi->sample_row = 0;
+	memset(mi->sample_table, 0xff, SAMPLE_COLUMNS * mi->n_rates);
+
+	for (col = 0; col < SAMPLE_COLUMNS; col++) {
+		prandom_bytes(rnd, sizeof(rnd));
+		for (i = 0; i < mi->n_rates; i++) {
+			new_idx = (i + rnd[i & 7]) % mi->n_rates;
+			while (SAMPLE_TBL(mi, new_idx, col) != 0xff)
+				new_idx = (new_idx + 1) % mi->n_rates;
+
+			SAMPLE_TBL(mi, new_idx, col) = i;
+		}
+	}
+}
+
+static void
+minstrel_rate_init(void *priv, struct ieee80211_supported_band *sband,
+		   struct cfg80211_chan_def *chandef,
+		   struct ieee80211_sta *sta, void *priv_sta)
+{
+	struct minstrel_sta_info *mi = priv_sta;
+	struct minstrel_priv *mp = priv;
+	struct ieee80211_rate *ctl_rate;
+	unsigned int i, n = 0;
+	unsigned int t_slot = 9; /* FIXME: get real slot time */
+	u32 rate_flags;
+
+	mi->sta = sta;
+	mi->lowest_rix = rate_lowest_index(sband, sta);
+	ctl_rate = &sband->bitrates[mi->lowest_rix];
+	mi->sp_ack_dur = ieee80211_frame_duration(sband->band, 10,
+				ctl_rate->bitrate,
+				!!(ctl_rate->flags & IEEE80211_RATE_ERP_G), 1,
+				ieee80211_chandef_get_shift(chandef));
+
+	rate_flags = ieee80211_chandef_rate_flags(&mp->hw->conf.chandef);
+	memset(mi->max_tp_rate, 0, sizeof(mi->max_tp_rate));
+	mi->max_prob_rate = 0;
+
+	for (i = 0; i < sband->n_bitrates; i++) {
+		struct minstrel_rate *mr = &mi->r[n];
+		struct minstrel_rate_stats *mrs = &mi->r[n].stats;
+		unsigned int tx_time = 0, tx_time_cts = 0, tx_time_rtscts = 0;
+		unsigned int tx_time_single;
+		unsigned int cw = mp->cw_min;
+		int shift;
+
+		if (!rate_supported(sta, sband->band, i))
+			continue;
+		if ((rate_flags & sband->bitrates[i].flags) != rate_flags)
+			continue;
+
+		n++;
+		memset(mr, 0, sizeof(*mr));
+		memset(mrs, 0, sizeof(*mrs));
+
+		mr->rix = i;
+		shift = ieee80211_chandef_get_shift(chandef);
+		mr->bitrate = DIV_ROUND_UP(sband->bitrates[i].bitrate,
+					   (1 << shift) * 5);
+		calc_rate_durations(sband->band, mr, &sband->bitrates[i],
+				    chandef);
+
+		/* calculate maximum number of retransmissions before
+		 * fallback (based on maximum segment size) */
+		mr->sample_limit = -1;
+		mrs->retry_count = 1;
+		mr->retry_count_cts = 1;
+		mrs->retry_count_rtscts = 1;
+		tx_time = mr->perfect_tx_time + mi->sp_ack_dur;
+		do {
+			/* add one retransmission */
+			tx_time_single = mr->ack_time + mr->perfect_tx_time;
+
+			/* contention window */
+			tx_time_single += (t_slot * cw) >> 1;
+			cw = min((cw << 1) | 1, mp->cw_max);
+
+			tx_time += tx_time_single;
+			tx_time_cts += tx_time_single + mi->sp_ack_dur;
+			tx_time_rtscts += tx_time_single + 2 * mi->sp_ack_dur;
+			if ((tx_time_cts < mp->segment_size) &&
+				(mr->retry_count_cts < mp->max_retry))
+				mr->retry_count_cts++;
+			if ((tx_time_rtscts < mp->segment_size) &&
+				(mrs->retry_count_rtscts < mp->max_retry))
+				mrs->retry_count_rtscts++;
+		} while ((tx_time < mp->segment_size) &&
+				(++mr->stats.retry_count < mp->max_retry));
+		mr->adjusted_retry_count = mrs->retry_count;
+		if (!(sband->bitrates[i].flags & IEEE80211_RATE_ERP_G))
+			mr->retry_count_cts = mrs->retry_count;
+	}
+
+	for (i = n; i < sband->n_bitrates; i++) {
+		struct minstrel_rate *mr = &mi->r[i];
+		mr->rix = -1;
+	}
+
+	mi->n_rates = n;
+	mi->last_stats_update = jiffies;
+
+	init_sample_table(mi);
+	minstrel_update_rates(mp, mi);
+}
+
+static void *
+minstrel_alloc_sta(void *priv, struct ieee80211_sta *sta, gfp_t gfp)
+{
+	struct ieee80211_supported_band *sband;
+	struct minstrel_sta_info *mi;
+	struct minstrel_priv *mp = priv;
+	struct ieee80211_hw *hw = mp->hw;
+	int max_rates = 0;
+	int i;
+
+	mi = kzalloc(sizeof(struct minstrel_sta_info), gfp);
+	if (!mi)
+		return NULL;
+
+	for (i = 0; i < NUM_NL80211_BANDS; i++) {
+		sband = hw->wiphy->bands[i];
+		if (sband && sband->n_bitrates > max_rates)
+			max_rates = sband->n_bitrates;
+	}
+
+	mi->r = kcalloc(max_rates, sizeof(struct minstrel_rate), gfp);
+	if (!mi->r)
+		goto error;
+
+	mi->sample_table = kmalloc_array(max_rates, SAMPLE_COLUMNS, gfp);
+	if (!mi->sample_table)
+		goto error1;
+
+	mi->last_stats_update = jiffies;
+	return mi;
+
+error1:
+	kfree(mi->r);
+error:
+	kfree(mi);
+	return NULL;
+}
+
+static void
+minstrel_free_sta(void *priv, struct ieee80211_sta *sta, void *priv_sta)
+{
+	struct minstrel_sta_info *mi = priv_sta;
+
+	kfree(mi->sample_table);
+	kfree(mi->r);
+	kfree(mi);
+}
+
+static void
+minstrel_init_cck_rates(struct minstrel_priv *mp)
+{
+	static const int bitrates[4] = { 10, 20, 55, 110 };
+	struct ieee80211_supported_band *sband;
+	u32 rate_flags = ieee80211_chandef_rate_flags(&mp->hw->conf.chandef);
+	int i, j;
+
+	sband = mp->hw->wiphy->bands[NL80211_BAND_2GHZ];
+	if (!sband)
+		return;
+
+	for (i = 0, j = 0; i < sband->n_bitrates; i++) {
+		struct ieee80211_rate *rate = &sband->bitrates[i];
+
+		if (rate->flags & IEEE80211_RATE_ERP_G)
+			continue;
+
+		if ((rate_flags & sband->bitrates[i].flags) != rate_flags)
+			continue;
+
+		for (j = 0; j < ARRAY_SIZE(bitrates); j++) {
+			if (rate->bitrate != bitrates[j])
+				continue;
+
+			mp->cck_rates[j] = i;
+			break;
+		}
+	}
+}
+
+static void *
+minstrel_alloc(struct ieee80211_hw *hw, struct dentry *debugfsdir)
+{
+	struct minstrel_priv *mp;
+
+	mp = kzalloc(sizeof(struct minstrel_priv), GFP_ATOMIC);
+	if (!mp)
+		return NULL;
+
+	/* contention window settings
+	 * Just an approximation. Using the per-queue values would complicate
+	 * the calculations and is probably unnecessary */
+	mp->cw_min = 15;
+	mp->cw_max = 1023;
+
+	/* number of packets (in %) to use for sampling other rates
+	 * sample less often for non-mrr packets, because the overhead
+	 * is much higher than with mrr */
+	mp->lookaround_rate = 5;
+	mp->lookaround_rate_mrr = 10;
+
+	/* maximum time that the hw is allowed to stay in one MRR segment */
+	mp->segment_size = 6000;
+
+	if (hw->max_rate_tries > 0)
+		mp->max_retry = hw->max_rate_tries;
+	else
+		/* safe default, does not necessarily have to match hw properties */
+		mp->max_retry = 7;
+
+	if (hw->max_rates >= 4)
+		mp->has_mrr = true;
+
+	mp->hw = hw;
+	mp->update_interval = 100;
+
+#ifdef CONFIG_MAC80211_DEBUGFS
+	mp->fixed_rate_idx = (u32) -1;
+	mp->dbg_fixed_rate = debugfs_create_u32("fixed_rate_idx",
+			0666, debugfsdir, &mp->fixed_rate_idx);
+#endif
+
+	minstrel_init_cck_rates(mp);
+
+	return mp;
+}
+
+static void
+minstrel_free(void *priv)
+{
+#ifdef CONFIG_MAC80211_DEBUGFS
+	debugfs_remove(((struct minstrel_priv *)priv)->dbg_fixed_rate);
+#endif
+	kfree(priv);
+}
+
+static u32 minstrel_get_expected_throughput(void *priv_sta)
+{
+	struct minstrel_sta_info *mi = priv_sta;
+	struct minstrel_rate_stats *tmp_mrs;
+	int idx = mi->max_tp_rate[0];
+	int tmp_cur_tp;
+
+	/* convert pkt per sec in kbps (1200 is the average pkt size used for
+	 * computing cur_tp
+	 */
+	tmp_mrs = &mi->r[idx].stats;
+	tmp_cur_tp = minstrel_get_tp_avg(&mi->r[idx], tmp_mrs->prob_ewma) * 10;
+	tmp_cur_tp = tmp_cur_tp * 1200 * 8 / 1024;
+
+	return tmp_cur_tp;
+}
+
+const struct rate_control_ops mac80211_minstrel = {
+	.name = "minstrel",
+	.tx_status_ext = minstrel_tx_status,
+	.get_rate = minstrel_get_rate,
+	.rate_init = minstrel_rate_init,
+	.alloc = minstrel_alloc,
+	.free = minstrel_free,
+	.alloc_sta = minstrel_alloc_sta,
+	.free_sta = minstrel_free_sta,
+#ifdef CONFIG_MAC80211_DEBUGFS
+	.add_sta_debugfs = minstrel_add_sta_debugfs,
+	.remove_sta_debugfs = minstrel_remove_sta_debugfs,
+#endif
+	.get_expected_throughput = minstrel_get_expected_throughput,
+};
+
+int __init
+rc80211_minstrel_init(void)
+{
+	return ieee80211_rate_control_register(&mac80211_minstrel);
+}
+
+void
+rc80211_minstrel_exit(void)
+{
+	ieee80211_rate_control_unregister(&mac80211_minstrel);
+}