1 files changed, 1070 insertions, 0 deletions

diff --git a/net/mac80211/rc80211_minstrel_ht.c b/net/mac80211/rc80211_minstrel_ht.c
new file mode 100644
index 0000000..2f4cc44
--- /dev/null
+++ b/net/mac80211/rc80211_minstrel_ht.c
@@ -0,0 +1,1070 @@
+/*
+ * Copyright (C) 2010-2013 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.
+ */
+#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 <net/mac80211.h>
+#include "rate.h"
+#include "rc80211_minstrel.h"
+#include "rc80211_minstrel_ht.h"
+
+#define AVG_PKT_SIZE	1200
+
+/* Number of bits for an average sized packet */
+#define MCS_NBITS (AVG_PKT_SIZE << 3)
+
+/* Number of symbols for a packet with (bps) bits per symbol */
+#define MCS_NSYMS(bps) ((MCS_NBITS + (bps) - 1) / (bps))
+
+/* Transmission time (nanoseconds) for a packet containing (syms) symbols */
+#define MCS_SYMBOL_TIME(sgi, syms)					\
+	(sgi ?								\
+	  ((syms) * 18000 + 4000) / 5 :	/* syms * 3.6 us */		\
+	  ((syms) * 1000) << 2		/* syms * 4 us */		\
+	)
+
+/* Transmit duration for the raw data part of an average sized packet */
+#define MCS_DURATION(streams, sgi, bps) MCS_SYMBOL_TIME(sgi, MCS_NSYMS((streams) * (bps)))
+
+/*
+ * Define group sort order: HT40 -> SGI -> #streams
+ */
+#define GROUP_IDX(_streams, _sgi, _ht40)	\
+	MINSTREL_MAX_STREAMS * 2 * _ht40 +	\
+	MINSTREL_MAX_STREAMS * _sgi +		\
+	_streams - 1
+
+/* MCS rate information for an MCS group */
+#define MCS_GROUP(_streams, _sgi, _ht40)				\
+	[GROUP_IDX(_streams, _sgi, _ht40)] = {				\
+	.streams = _streams,						\
+	.flags =							\
+		(_sgi ? IEEE80211_TX_RC_SHORT_GI : 0) |			\
+		(_ht40 ? IEEE80211_TX_RC_40_MHZ_WIDTH : 0),		\
+	.duration = {							\
+		MCS_DURATION(_streams, _sgi, _ht40 ? 54 : 26),		\
+		MCS_DURATION(_streams, _sgi, _ht40 ? 108 : 52),		\
+		MCS_DURATION(_streams, _sgi, _ht40 ? 162 : 78),		\
+		MCS_DURATION(_streams, _sgi, _ht40 ? 216 : 104),	\
+		MCS_DURATION(_streams, _sgi, _ht40 ? 324 : 156),	\
+		MCS_DURATION(_streams, _sgi, _ht40 ? 432 : 208),	\
+		MCS_DURATION(_streams, _sgi, _ht40 ? 486 : 234),	\
+		MCS_DURATION(_streams, _sgi, _ht40 ? 540 : 260)		\
+	}								\
+}
+
+#define CCK_DURATION(_bitrate, _short, _len)		\
+	(1000 * (10 /* SIFS */ +			\
+	 (_short ? 72 + 24 : 144 + 48 ) +		\
+	 (8 * (_len + 4) * 10) / (_bitrate)))
+
+#define CCK_ACK_DURATION(_bitrate, _short)			\
+	(CCK_DURATION((_bitrate > 10 ? 20 : 10), false, 60) +	\
+	 CCK_DURATION(_bitrate, _short, AVG_PKT_SIZE))
+
+#define CCK_DURATION_LIST(_short)			\
+	CCK_ACK_DURATION(10, _short),			\
+	CCK_ACK_DURATION(20, _short),			\
+	CCK_ACK_DURATION(55, _short),			\
+	CCK_ACK_DURATION(110, _short)
+
+#define CCK_GROUP						\
+	[MINSTREL_MAX_STREAMS * MINSTREL_STREAM_GROUPS] = {	\
+		.streams = 0,					\
+		.duration = {					\
+			CCK_DURATION_LIST(false),		\
+			CCK_DURATION_LIST(true)			\
+		}						\
+	}
+
+/*
+ * To enable sufficiently targeted rate sampling, MCS rates are divided into
+ * groups, based on the number of streams and flags (HT40, SGI) that they
+ * use.
+ *
+ * Sortorder has to be fixed for GROUP_IDX macro to be applicable:
+ * HT40 -> SGI -> #streams
+ */
+const struct mcs_group minstrel_mcs_groups[] = {
+	MCS_GROUP(1, 0, 0),
+	MCS_GROUP(2, 0, 0),
+#if MINSTREL_MAX_STREAMS >= 3
+	MCS_GROUP(3, 0, 0),
+#endif
+
+	MCS_GROUP(1, 1, 0),
+	MCS_GROUP(2, 1, 0),
+#if MINSTREL_MAX_STREAMS >= 3
+	MCS_GROUP(3, 1, 0),
+#endif
+
+	MCS_GROUP(1, 0, 1),
+	MCS_GROUP(2, 0, 1),
+#if MINSTREL_MAX_STREAMS >= 3
+	MCS_GROUP(3, 0, 1),
+#endif
+
+	MCS_GROUP(1, 1, 1),
+	MCS_GROUP(2, 1, 1),
+#if MINSTREL_MAX_STREAMS >= 3
+	MCS_GROUP(3, 1, 1),
+#endif
+
+	/* must be last */
+	CCK_GROUP
+};
+
+#define MINSTREL_CCK_GROUP	(ARRAY_SIZE(minstrel_mcs_groups) - 1)
+
+static u8 sample_table[SAMPLE_COLUMNS][MCS_GROUP_RATES];
+
+static void
+minstrel_ht_update_rates(struct minstrel_priv *mp, struct minstrel_ht_sta *mi);
+
+/*
+ * Look up an MCS group index based on mac80211 rate information
+ */
+static int
+minstrel_ht_get_group_idx(struct ieee80211_tx_rate *rate)
+{
+	return GROUP_IDX((rate->idx / MCS_GROUP_RATES) + 1,
+			 !!(rate->flags & IEEE80211_TX_RC_SHORT_GI),
+			 !!(rate->flags & IEEE80211_TX_RC_40_MHZ_WIDTH));
+}
+
+static struct minstrel_rate_stats *
+minstrel_ht_get_stats(struct minstrel_priv *mp, struct minstrel_ht_sta *mi,
+		      struct ieee80211_tx_rate *rate)
+{
+	int group, idx;
+
+	if (rate->flags & IEEE80211_TX_RC_MCS) {
+		group = minstrel_ht_get_group_idx(rate);
+		idx = rate->idx % MCS_GROUP_RATES;
+	} else {
+		group = MINSTREL_CCK_GROUP;
+
+		for (idx = 0; idx < ARRAY_SIZE(mp->cck_rates); idx++)
+			if (rate->idx == mp->cck_rates[idx])
+				break;
+
+		/* short preamble */
+		if (!(mi->groups[group].supported & BIT(idx)))
+			idx += 4;
+	}
+	return &mi->groups[group].rates[idx];
+}
+
+static inline struct minstrel_rate_stats *
+minstrel_get_ratestats(struct minstrel_ht_sta *mi, int index)
+{
+	return &mi->groups[index / MCS_GROUP_RATES].rates[index % MCS_GROUP_RATES];
+}
+
+
+/*
+ * Recalculate success probabilities and counters for a rate using EWMA
+ */
+static void
+minstrel_calc_rate_ewma(struct minstrel_rate_stats *mr)
+{
+	if (unlikely(mr->attempts > 0)) {
+		mr->sample_skipped = 0;
+		mr->cur_prob = MINSTREL_FRAC(mr->success, mr->attempts);
+		if (!mr->att_hist)
+			mr->probability = mr->cur_prob;
+		else
+			mr->probability = minstrel_ewma(mr->probability,
+				mr->cur_prob, EWMA_LEVEL);
+		mr->att_hist += mr->attempts;
+		mr->succ_hist += mr->success;
+	} else {
+		mr->sample_skipped++;
+	}
+	mr->last_success = mr->success;
+	mr->last_attempts = mr->attempts;
+	mr->success = 0;
+	mr->attempts = 0;
+}
+
+/*
+ * Calculate throughput based on the average A-MPDU length, taking into account
+ * the expected number of retransmissions and their expected length
+ */
+static void
+minstrel_ht_calc_tp(struct minstrel_ht_sta *mi, int group, int rate)
+{
+	struct minstrel_rate_stats *mr;
+	unsigned int nsecs = 0;
+	unsigned int tp;
+	unsigned int prob;
+
+	mr = &mi->groups[group].rates[rate];
+	prob = mr->probability;
+
+	if (prob < MINSTREL_FRAC(1, 10)) {
+		mr->cur_tp = 0;
+		return;
+	}
+
+	/*
+	 * For the throughput calculation, limit the probability value to 90% to
+	 * account for collision related packet error rate fluctuation
+	 */
+	if (prob > MINSTREL_FRAC(9, 10))
+		prob = MINSTREL_FRAC(9, 10);
+
+	if (group != MINSTREL_CCK_GROUP)
+		nsecs = 1000 * mi->overhead / MINSTREL_TRUNC(mi->avg_ampdu_len);
+
+	nsecs += minstrel_mcs_groups[group].duration[rate];
+	tp = 1000000 * ((mr->probability * 1000) / nsecs);
+
+	mr->cur_tp = MINSTREL_TRUNC(tp);
+}
+
+/*
+ * Update rate statistics and select new primary rates
+ *
+ * Rules for rate selection:
+ *  - max_prob_rate must use only one stream, as a tradeoff between delivery
+ *    probability and throughput during strong fluctuations
+ *  - as long as the max prob rate has a probability of more than 3/4, pick
+ *    higher throughput rates, even if the probablity is a bit lower
+ */
+static void
+minstrel_ht_update_stats(struct minstrel_priv *mp, struct minstrel_ht_sta *mi)
+{
+	struct minstrel_mcs_group_data *mg;
+	struct minstrel_rate_stats *mr;
+	int cur_prob, cur_prob_tp, cur_tp, cur_tp2;
+	int group, i, index;
+	bool mi_rates_valid = false;
+
+	if (mi->ampdu_packets > 0) {
+		mi->avg_ampdu_len = minstrel_ewma(mi->avg_ampdu_len,
+			MINSTREL_FRAC(mi->ampdu_len, mi->ampdu_packets), EWMA_LEVEL);
+		mi->ampdu_len = 0;
+		mi->ampdu_packets = 0;
+	}
+
+	mi->sample_slow = 0;
+	mi->sample_count = 0;
+
+	for (group = 0; group < ARRAY_SIZE(minstrel_mcs_groups); group++) {
+		bool mg_rates_valid = false;
+
+		cur_prob = 0;
+		cur_prob_tp = 0;
+		cur_tp = 0;
+		cur_tp2 = 0;
+
+		mg = &mi->groups[group];
+		if (!mg->supported)
+			continue;
+
+		mi->sample_count++;
+
+		for (i = 0; i < MCS_GROUP_RATES; i++) {
+			if (!(mg->supported & BIT(i)))
+				continue;
+
+			/* initialize rates selections starting indexes */
+			if (!mg_rates_valid) {
+				mg->max_tp_rate = mg->max_tp_rate2 =
+					mg->max_prob_rate = i;
+				if (!mi_rates_valid) {
+					mi->max_tp_rate = mi->max_tp_rate2 =
+						mi->max_prob_rate = i;
+					mi_rates_valid = true;
+				}
+				mg_rates_valid = true;
+			}
+
+			mr = &mg->rates[i];
+			mr->retry_updated = false;
+			index = MCS_GROUP_RATES * group + i;
+			minstrel_calc_rate_ewma(mr);
+			minstrel_ht_calc_tp(mi, group, i);
+
+			if (!mr->cur_tp)
+				continue;
+
+			if ((mr->cur_tp > cur_prob_tp && mr->probability >
+			     MINSTREL_FRAC(3, 4)) || mr->probability > cur_prob) {
+				mg->max_prob_rate = index;
+				cur_prob = mr->probability;
+				cur_prob_tp = mr->cur_tp;
+			}
+
+			if (mr->cur_tp > cur_tp) {
+				swap(index, mg->max_tp_rate);
+				cur_tp = mr->cur_tp;
+				mr = minstrel_get_ratestats(mi, index);
+			}
+
+			if (index >= mg->max_tp_rate)
+				continue;
+
+			if (mr->cur_tp > cur_tp2) {
+				mg->max_tp_rate2 = index;
+				cur_tp2 = mr->cur_tp;
+			}
+		}
+	}
+
+	/* try to sample all available rates during each interval */
+	mi->sample_count *= 8;
+
+	cur_prob = 0;
+	cur_prob_tp = 0;
+	cur_tp = 0;
+	cur_tp2 = 0;
+	for (group = 0; group < ARRAY_SIZE(minstrel_mcs_groups); group++) {
+		mg = &mi->groups[group];
+		if (!mg->supported)
+			continue;
+
+		mr = minstrel_get_ratestats(mi, mg->max_tp_rate);
+		if (cur_tp < mr->cur_tp) {
+			mi->max_tp_rate2 = mi->max_tp_rate;
+			cur_tp2 = cur_tp;
+			mi->max_tp_rate = mg->max_tp_rate;
+			cur_tp = mr->cur_tp;
+			mi->max_prob_streams = minstrel_mcs_groups[group].streams - 1;
+		}
+
+		mr = minstrel_get_ratestats(mi, mg->max_tp_rate2);
+		if (cur_tp2 < mr->cur_tp) {
+			mi->max_tp_rate2 = mg->max_tp_rate2;
+			cur_tp2 = mr->cur_tp;
+		}
+	}
+
+	if (mi->max_prob_streams < 1)
+		mi->max_prob_streams = 1;
+
+	for (group = 0; group < ARRAY_SIZE(minstrel_mcs_groups); group++) {
+		mg = &mi->groups[group];
+		if (!mg->supported)
+			continue;
+		mr = minstrel_get_ratestats(mi, mg->max_prob_rate);
+		if (cur_prob_tp < mr->cur_tp &&
+		    minstrel_mcs_groups[group].streams <= mi->max_prob_streams) {
+			mi->max_prob_rate = mg->max_prob_rate;
+			cur_prob = mr->cur_prob;
+			cur_prob_tp = mr->cur_tp;
+		}
+	}
+
+
+	mi->stats_update = jiffies;
+}
+
+static bool
+minstrel_ht_txstat_valid(struct minstrel_priv *mp, struct ieee80211_tx_rate *rate)
+{
+	if (rate->idx < 0)
+		return false;
+
+	if (!rate->count)
+		return false;
+
+	if (rate->flags & IEEE80211_TX_RC_MCS)
+		return true;
+
+	return rate->idx == mp->cck_rates[0] ||
+	       rate->idx == mp->cck_rates[1] ||
+	       rate->idx == mp->cck_rates[2] ||
+	       rate->idx == mp->cck_rates[3];
+}
+
+static void
+minstrel_next_sample_idx(struct minstrel_ht_sta *mi)
+{
+	struct minstrel_mcs_group_data *mg;
+
+	for (;;) {
+		mi->sample_group++;
+		mi->sample_group %= ARRAY_SIZE(minstrel_mcs_groups);
+		mg = &mi->groups[mi->sample_group];
+
+		if (!mg->supported)
+			continue;
+
+		if (++mg->index >= MCS_GROUP_RATES) {
+			mg->index = 0;
+			if (++mg->column >= ARRAY_SIZE(sample_table))
+				mg->column = 0;
+		}
+		break;
+	}
+}
+
+static void
+minstrel_downgrade_rate(struct minstrel_ht_sta *mi, unsigned int *idx,
+			bool primary)
+{
+	int group, orig_group;
+
+	orig_group = group = *idx / MCS_GROUP_RATES;
+	while (group > 0) {
+		group--;
+
+		if (!mi->groups[group].supported)
+			continue;
+
+		if (minstrel_mcs_groups[group].streams >
+		    minstrel_mcs_groups[orig_group].streams)
+			continue;
+
+		if (primary)
+			*idx = mi->groups[group].max_tp_rate;
+		else
+			*idx = mi->groups[group].max_tp_rate2;
+		break;
+	}
+}
+
+static void
+minstrel_aggr_check(struct ieee80211_sta *pubsta, struct sk_buff *skb)
+{
+	struct ieee80211_hdr *hdr = (struct ieee80211_hdr *) skb->data;
+	struct sta_info *sta = container_of(pubsta, struct sta_info, sta);
+	u16 tid;
+
+	if (unlikely(!ieee80211_is_data_qos(hdr->frame_control)))
+		return;
+
+	if (unlikely(skb->protocol == cpu_to_be16(ETH_P_PAE)))
+		return;
+
+	tid = *ieee80211_get_qos_ctl(hdr) & IEEE80211_QOS_CTL_TID_MASK;
+	if (likely(sta->ampdu_mlme.tid_tx[tid]))
+		return;
+
+	if (skb_get_queue_mapping(skb) == IEEE80211_AC_VO)
+		return;
+
+	ieee80211_start_tx_ba_session(pubsta, tid, 5000);
+}
+
+static void
+minstrel_ht_tx_status(void *priv, struct ieee80211_supported_band *sband,
+                      struct ieee80211_sta *sta, void *priv_sta,
+                      struct sk_buff *skb)
+{
+	struct minstrel_ht_sta_priv *msp = priv_sta;
+	struct minstrel_ht_sta *mi = &msp->ht;
+	struct ieee80211_tx_info *info = IEEE80211_SKB_CB(skb);
+	struct ieee80211_tx_rate *ar = info->status.rates;
+	struct minstrel_rate_stats *rate, *rate2;
+	struct minstrel_priv *mp = priv;
+	bool last, update = false;
+	int i;
+
+	if (!msp->is_ht)
+		return mac80211_minstrel.tx_status(priv, sband, sta, &msp->legacy, skb);
+
+	/* This packet was aggregated but doesn't carry status info */
+	if ((info->flags & IEEE80211_TX_CTL_AMPDU) &&
+	    !(info->flags & IEEE80211_TX_STAT_AMPDU))
+		return;
+
+	if (!(info->flags & IEEE80211_TX_STAT_AMPDU)) {
+		info->status.ampdu_ack_len =
+			(info->flags & IEEE80211_TX_STAT_ACK ? 1 : 0);
+		info->status.ampdu_len = 1;
+	}
+
+	mi->ampdu_packets++;
+	mi->ampdu_len += info->status.ampdu_len;
+
+	if (!mi->sample_wait && !mi->sample_tries && mi->sample_count > 0) {
+		mi->sample_wait = 16 + 2 * MINSTREL_TRUNC(mi->avg_ampdu_len);
+		mi->sample_tries = 1;
+		mi->sample_count--;
+	}
+
+	if (info->flags & IEEE80211_TX_CTL_RATE_CTRL_PROBE)
+		mi->sample_packets += info->status.ampdu_len;
+
+	last = !minstrel_ht_txstat_valid(mp, &ar[0]);
+	for (i = 0; !last; i++) {
+		last = (i == IEEE80211_TX_MAX_RATES - 1) ||
+		       !minstrel_ht_txstat_valid(mp, &ar[i + 1]);
+
+		rate = minstrel_ht_get_stats(mp, mi, &ar[i]);
+
+		if (last)
+			rate->success += info->status.ampdu_ack_len;
+
+		rate->attempts += ar[i].count * info->status.ampdu_len;
+	}
+
+	/*
+	 * check for sudden death of spatial multiplexing,
+	 * downgrade to a lower number of streams if necessary.
+	 */
+	rate = minstrel_get_ratestats(mi, mi->max_tp_rate);
+	if (rate->attempts > 30 &&
+	    MINSTREL_FRAC(rate->success, rate->attempts) <
+	    MINSTREL_FRAC(20, 100)) {
+		minstrel_downgrade_rate(mi, &mi->max_tp_rate, true);
+		update = true;
+	}
+
+	rate2 = minstrel_get_ratestats(mi, mi->max_tp_rate2);
+	if (rate2->attempts > 30 &&
+	    MINSTREL_FRAC(rate2->success, rate2->attempts) <
+	    MINSTREL_FRAC(20, 100)) {
+		minstrel_downgrade_rate(mi, &mi->max_tp_rate2, false);
+		update = true;
+	}
+
+	if (time_after(jiffies, mi->stats_update + (mp->update_interval / 2 * HZ) / 1000)) {
+		update = true;
+		minstrel_ht_update_stats(mp, mi);
+		if (!(info->flags & IEEE80211_TX_CTL_AMPDU) &&
+		    mi->max_prob_rate / MCS_GROUP_RATES != MINSTREL_CCK_GROUP)
+			minstrel_aggr_check(sta, skb);
+	}
+
+	if (update)
+		minstrel_ht_update_rates(mp, mi);
+}
+
+static void
+minstrel_calc_retransmit(struct minstrel_priv *mp, struct minstrel_ht_sta *mi,
+                         int index)
+{
+	struct minstrel_rate_stats *mr;
+	const struct mcs_group *group;
+	unsigned int tx_time, tx_time_rtscts, tx_time_data;
+	unsigned int cw = mp->cw_min;
+	unsigned int ctime = 0;
+	unsigned int t_slot = 9; /* FIXME */
+	unsigned int ampdu_len = MINSTREL_TRUNC(mi->avg_ampdu_len);
+	unsigned int overhead = 0, overhead_rtscts = 0;
+
+	mr = minstrel_get_ratestats(mi, index);
+	if (mr->probability < MINSTREL_FRAC(1, 10)) {
+		mr->retry_count = 1;
+		mr->retry_count_rtscts = 1;
+		return;
+	}
+
+	mr->retry_count = 2;
+	mr->retry_count_rtscts = 2;
+	mr->retry_updated = true;
+
+	group = &minstrel_mcs_groups[index / MCS_GROUP_RATES];
+	tx_time_data = group->duration[index % MCS_GROUP_RATES] * ampdu_len / 1000;
+
+	/* Contention time for first 2 tries */
+	ctime = (t_slot * cw) >> 1;
+	cw = min((cw << 1) | 1, mp->cw_max);
+	ctime += (t_slot * cw) >> 1;
+	cw = min((cw << 1) | 1, mp->cw_max);
+
+	if (index / MCS_GROUP_RATES != MINSTREL_CCK_GROUP) {
+		overhead = mi->overhead;
+		overhead_rtscts = mi->overhead_rtscts;
+	}
+
+	/* Total TX time for data and Contention after first 2 tries */
+	tx_time = ctime + 2 * (overhead + tx_time_data);
+	tx_time_rtscts = ctime + 2 * (overhead_rtscts + tx_time_data);
+
+	/* See how many more tries we can fit inside segment size */
+	do {
+		/* Contention time for this try */
+		ctime = (t_slot * cw) >> 1;
+		cw = min((cw << 1) | 1, mp->cw_max);
+
+		/* Total TX time after this try */
+		tx_time += ctime + overhead + tx_time_data;
+		tx_time_rtscts += ctime + overhead_rtscts + tx_time_data;
+
+		if (tx_time_rtscts < mp->segment_size)
+			mr->retry_count_rtscts++;
+	} while ((tx_time < mp->segment_size) &&
+	         (++mr->retry_count < mp->max_retry));
+}
+
+
+static void
+minstrel_ht_set_rate(struct minstrel_priv *mp, struct minstrel_ht_sta *mi,
+                     struct ieee80211_sta_rates *ratetbl, int offset, int index)
+{
+	const struct mcs_group *group = &minstrel_mcs_groups[index / MCS_GROUP_RATES];
+	struct minstrel_rate_stats *mr;
+	u8 idx;
+	u16 flags;
+
+	mr = minstrel_get_ratestats(mi, index);
+	if (!mr->retry_updated)
+		minstrel_calc_retransmit(mp, mi, index);
+
+	if (mr->probability < MINSTREL_FRAC(20, 100) || !mr->retry_count) {
+		ratetbl->rate[offset].count = 2;
+		ratetbl->rate[offset].count_rts = 2;
+		ratetbl->rate[offset].count_cts = 2;
+	} else {
+		ratetbl->rate[offset].count = mr->retry_count;
+		ratetbl->rate[offset].count_cts = mr->retry_count;
+		ratetbl->rate[offset].count_rts = mr->retry_count_rtscts;
+	}
+
+	if (index / MCS_GROUP_RATES == MINSTREL_CCK_GROUP) {
+		idx = mp->cck_rates[index % ARRAY_SIZE(mp->cck_rates)];
+		flags = 0;
+	} else {
+		idx = index % MCS_GROUP_RATES +
+		      (group->streams - 1) * MCS_GROUP_RATES;
+		flags = IEEE80211_TX_RC_MCS | group->flags;
+	}
+
+	if (offset > 0) {
+		ratetbl->rate[offset].count = ratetbl->rate[offset].count_rts;
+		flags |= IEEE80211_TX_RC_USE_RTS_CTS;
+	}
+
+	ratetbl->rate[offset].idx = idx;
+	ratetbl->rate[offset].flags = flags;
+}
+
+static void
+minstrel_ht_update_rates(struct minstrel_priv *mp, struct minstrel_ht_sta *mi)
+{
+	struct ieee80211_sta_rates *rates;
+	int i = 0;
+
+	rates = kzalloc(sizeof(*rates), GFP_ATOMIC);
+	if (!rates)
+		return;
+
+	/* Start with max_tp_rate */
+	minstrel_ht_set_rate(mp, mi, rates, i++, mi->max_tp_rate);
+
+	if (mp->hw->max_rates >= 3) {
+		/* At least 3 tx rates supported, use max_tp_rate2 next */
+		minstrel_ht_set_rate(mp, mi, rates, i++, mi->max_tp_rate2);
+	}
+
+	if (mp->hw->max_rates >= 2) {
+		/*
+		 * At least 2 tx rates supported, use max_prob_rate next */
+		minstrel_ht_set_rate(mp, mi, rates, i++, mi->max_prob_rate);
+	}
+
+	rates->rate[i].idx = -1;
+	rate_control_set_rates(mp->hw, mi->sta, rates);
+}
+
+static inline int
+minstrel_get_duration(int index)
+{
+	const struct mcs_group *group = &minstrel_mcs_groups[index / MCS_GROUP_RATES];
+	return group->duration[index % MCS_GROUP_RATES];
+}
+
+static int
+minstrel_get_sample_rate(struct minstrel_priv *mp, struct minstrel_ht_sta *mi)
+{
+	struct minstrel_rate_stats *mr;
+	struct minstrel_mcs_group_data *mg;
+	unsigned int sample_dur, sample_group;
+	int sample_idx = 0;
+
+	if (mi->sample_wait > 0) {
+		mi->sample_wait--;
+		return -1;
+	}
+
+	if (!mi->sample_tries)
+		return -1;
+
+	mg = &mi->groups[mi->sample_group];
+	sample_idx = sample_table[mg->column][mg->index];
+	mr = &mg->rates[sample_idx];
+	sample_group = mi->sample_group;
+	sample_idx += sample_group * MCS_GROUP_RATES;
+	minstrel_next_sample_idx(mi);
+
+	/*
+	 * Sampling might add some overhead (RTS, no aggregation)
+	 * to the frame. Hence, don't use sampling for the currently
+	 * used rates.
+	 */
+	if (sample_idx == mi->max_tp_rate ||
+	    sample_idx == mi->max_tp_rate2 ||
+	    sample_idx == mi->max_prob_rate)
+		return -1;
+
+	/*
+	 * Do not sample if the probability is already higher than 95%
+	 * to avoid wasting airtime.
+	 */
+	if (mr->probability > MINSTREL_FRAC(95, 100))
+		return -1;
+
+	/*
+	 * Make sure that lower rates get sampled only occasionally,
+	 * if the link is working perfectly.
+	 */
+	sample_dur = minstrel_get_duration(sample_idx);
+	if (sample_dur >= minstrel_get_duration(mi->max_tp_rate2) &&
+	    (mi->max_prob_streams <
+	     minstrel_mcs_groups[sample_group].streams ||
+	     sample_dur >= minstrel_get_duration(mi->max_prob_rate))) {
+		if (mr->sample_skipped < 20)
+			return -1;
+
+		if (mi->sample_slow++ > 2)
+			return -1;
+	}
+	mi->sample_tries--;
+
+	return sample_idx;
+}
+
+static void
+minstrel_ht_check_cck_shortpreamble(struct minstrel_priv *mp,
+				    struct minstrel_ht_sta *mi, bool val)
+{
+	u8 supported = mi->groups[MINSTREL_CCK_GROUP].supported;
+
+	if (!supported || !mi->cck_supported_short)
+		return;
+
+	if (supported & (mi->cck_supported_short << (val * 4)))
+		return;
+
+	supported ^= mi->cck_supported_short | (mi->cck_supported_short << 4);
+	mi->groups[MINSTREL_CCK_GROUP].supported = supported;
+}
+
+static void
+minstrel_ht_get_rate(void *priv, struct ieee80211_sta *sta, void *priv_sta,
+                     struct ieee80211_tx_rate_control *txrc)
+{
+	const struct mcs_group *sample_group;
+	struct ieee80211_tx_info *info = IEEE80211_SKB_CB(txrc->skb);
+	struct ieee80211_tx_rate *rate = &info->status.rates[0];
+	struct minstrel_ht_sta_priv *msp = priv_sta;
+	struct minstrel_ht_sta *mi = &msp->ht;
+	struct minstrel_priv *mp = priv;
+	int sample_idx;
+
+	if (rate_control_send_low(sta, priv_sta, txrc))
+		return;
+
+	if (!msp->is_ht)
+		return mac80211_minstrel.get_rate(priv, sta, &msp->legacy, txrc);
+
+	info->flags |= mi->tx_flags;
+	minstrel_ht_check_cck_shortpreamble(mp, mi, txrc->short_preamble);
+
+	/* Don't use EAPOL frames for sampling on non-mrr hw */
+	if (mp->hw->max_rates == 1 &&
+	    txrc->skb->protocol == cpu_to_be16(ETH_P_PAE))
+		sample_idx = -1;
+	else
+		sample_idx = minstrel_get_sample_rate(mp, mi);
+
+#ifdef CPTCFG_MAC80211_DEBUGFS
+	/* use fixed index if set */
+	if (mp->fixed_rate_idx != -1) {
+		mi->max_tp_rate = mp->fixed_rate_idx;
+		mi->max_tp_rate2 = mp->fixed_rate_idx;
+		mi->max_prob_rate = mp->fixed_rate_idx;
+		sample_idx = -1;
+	}
+#endif
+
+	mi->total_packets++;
+
+	/* wraparound */
+	if (mi->total_packets == ~0) {
+		mi->total_packets = 0;
+		mi->sample_packets = 0;
+	}
+
+	if (sample_idx < 0)
+		return;
+
+	sample_group = &minstrel_mcs_groups[sample_idx / MCS_GROUP_RATES];
+	info->flags |= IEEE80211_TX_CTL_RATE_CTRL_PROBE;
+	rate->count = 1;
+
+	if (sample_idx / MCS_GROUP_RATES == MINSTREL_CCK_GROUP) {
+		int idx = sample_idx % ARRAY_SIZE(mp->cck_rates);
+		rate->idx = mp->cck_rates[idx];
+		rate->flags = 0;
+		return;
+	}
+
+	rate->idx = sample_idx % MCS_GROUP_RATES +
+		    (sample_group->streams - 1) * MCS_GROUP_RATES;
+	rate->flags = IEEE80211_TX_RC_MCS | sample_group->flags;
+}
+
+static void
+minstrel_ht_update_cck(struct minstrel_priv *mp, struct minstrel_ht_sta *mi,
+		       struct ieee80211_supported_band *sband,
+		       struct ieee80211_sta *sta)
+{
+	int i;
+
+	if (sband->band != IEEE80211_BAND_2GHZ)
+		return;
+
+	if (!(mp->hw->flags & IEEE80211_HW_SUPPORTS_HT_CCK_RATES))
+		return;
+
+	mi->cck_supported = 0;
+	mi->cck_supported_short = 0;
+	for (i = 0; i < 4; i++) {
+		if (!rate_supported(sta, sband->band, mp->cck_rates[i]))
+			continue;
+
+		mi->cck_supported |= BIT(i);
+		if (sband->bitrates[i].flags & IEEE80211_RATE_SHORT_PREAMBLE)
+			mi->cck_supported_short |= BIT(i);
+	}
+
+	mi->groups[MINSTREL_CCK_GROUP].supported = mi->cck_supported;
+}
+
+static void
+minstrel_ht_update_caps(void *priv, struct ieee80211_supported_band *sband,
+                        struct ieee80211_sta *sta, void *priv_sta)
+{
+	struct minstrel_priv *mp = priv;
+	struct minstrel_ht_sta_priv *msp = priv_sta;
+	struct minstrel_ht_sta *mi = &msp->ht;
+	struct ieee80211_mcs_info *mcs = &sta->ht_cap.mcs;
+	u16 sta_cap = sta->ht_cap.cap;
+	int n_supported = 0;
+	int ack_dur;
+	int stbc;
+	int i;
+
+	/* fall back to the old minstrel for legacy stations */
+	if (!sta->ht_cap.ht_supported)
+		goto use_legacy;
+
+	BUILD_BUG_ON(ARRAY_SIZE(minstrel_mcs_groups) !=
+		MINSTREL_MAX_STREAMS * MINSTREL_STREAM_GROUPS + 1);
+
+	msp->is_ht = true;
+	memset(mi, 0, sizeof(*mi));
+
+	mi->sta = sta;
+	mi->stats_update = jiffies;
+
+	ack_dur = ieee80211_frame_duration(sband->band, 10, 60, 1, 1);
+	mi->overhead = ieee80211_frame_duration(sband->band, 0, 60, 1, 1) + ack_dur;
+	mi->overhead_rtscts = mi->overhead + 2 * ack_dur;
+
+	mi->avg_ampdu_len = MINSTREL_FRAC(1, 1);
+
+	/* When using MRR, sample more on the first attempt, without delay */
+	if (mp->has_mrr) {
+		mi->sample_count = 16;
+		mi->sample_wait = 0;
+	} else {
+		mi->sample_count = 8;
+		mi->sample_wait = 8;
+	}
+	mi->sample_tries = 4;
+
+	stbc = (sta_cap & IEEE80211_HT_CAP_RX_STBC) >>
+		IEEE80211_HT_CAP_RX_STBC_SHIFT;
+	mi->tx_flags |= stbc << IEEE80211_TX_CTL_STBC_SHIFT;
+
+	if (sta_cap & IEEE80211_HT_CAP_LDPC_CODING)
+		mi->tx_flags |= IEEE80211_TX_CTL_LDPC;
+
+	for (i = 0; i < ARRAY_SIZE(mi->groups); i++) {
+		mi->groups[i].supported = 0;
+		if (i == MINSTREL_CCK_GROUP) {
+			minstrel_ht_update_cck(mp, mi, sband, sta);
+			continue;
+		}
+
+		if (minstrel_mcs_groups[i].flags & IEEE80211_TX_RC_SHORT_GI) {
+			if (minstrel_mcs_groups[i].flags & IEEE80211_TX_RC_40_MHZ_WIDTH) {
+				if (!(sta_cap & IEEE80211_HT_CAP_SGI_40))
+					continue;
+			} else {
+				if (!(sta_cap & IEEE80211_HT_CAP_SGI_20))
+					continue;
+			}
+		}
+
+		if (minstrel_mcs_groups[i].flags & IEEE80211_TX_RC_40_MHZ_WIDTH &&
+		    sta->bandwidth < IEEE80211_STA_RX_BW_40)
+			continue;
+
+		/* Mark MCS > 7 as unsupported if STA is in static SMPS mode */
+		if (sta->smps_mode == IEEE80211_SMPS_STATIC &&
+		    minstrel_mcs_groups[i].streams > 1)
+			continue;
+
+		mi->groups[i].supported =
+			mcs->rx_mask[minstrel_mcs_groups[i].streams - 1];
+
+		if (mi->groups[i].supported)
+			n_supported++;
+	}
+
+	if (!n_supported)
+		goto use_legacy;
+
+	/* create an initial rate table with the lowest supported rates */
+	minstrel_ht_update_stats(mp, mi);
+	minstrel_ht_update_rates(mp, mi);
+
+	return;
+
+use_legacy:
+	msp->is_ht = false;
+	memset(&msp->legacy, 0, sizeof(msp->legacy));
+	msp->legacy.r = msp->ratelist;
+	msp->legacy.sample_table = msp->sample_table;
+	return mac80211_minstrel.rate_init(priv, sband, sta, &msp->legacy);
+}
+
+static void
+minstrel_ht_rate_init(void *priv, struct ieee80211_supported_band *sband,
+                      struct ieee80211_sta *sta, void *priv_sta)
+{
+	minstrel_ht_update_caps(priv, sband, sta, priv_sta);
+}
+
+static void
+minstrel_ht_rate_update(void *priv, struct ieee80211_supported_band *sband,
+                        struct ieee80211_sta *sta, void *priv_sta,
+                        u32 changed)
+{
+	minstrel_ht_update_caps(priv, sband, sta, priv_sta);
+}
+
+static void *
+minstrel_ht_alloc_sta(void *priv, struct ieee80211_sta *sta, gfp_t gfp)
+{
+	struct ieee80211_supported_band *sband;
+	struct minstrel_ht_sta_priv *msp;
+	struct minstrel_priv *mp = priv;
+	struct ieee80211_hw *hw = mp->hw;
+	int max_rates = 0;
+	int i;
+
+	for (i = 0; i < IEEE80211_NUM_BANDS; i++) {
+		sband = hw->wiphy->bands[i];
+		if (sband && sband->n_bitrates > max_rates)
+			max_rates = sband->n_bitrates;
+	}
+
+	msp = kzalloc(sizeof(*msp), gfp);
+	if (!msp)
+		return NULL;
+
+	msp->ratelist = kzalloc(sizeof(struct minstrel_rate) * max_rates, gfp);
+	if (!msp->ratelist)
+		goto error;
+
+	msp->sample_table = kmalloc(SAMPLE_COLUMNS * max_rates, gfp);
+	if (!msp->sample_table)
+		goto error1;
+
+	return msp;
+
+error1:
+	kfree(msp->ratelist);
+error:
+	kfree(msp);
+	return NULL;
+}
+
+static void
+minstrel_ht_free_sta(void *priv, struct ieee80211_sta *sta, void *priv_sta)
+{
+	struct minstrel_ht_sta_priv *msp = priv_sta;
+
+	kfree(msp->sample_table);
+	kfree(msp->ratelist);
+	kfree(msp);
+}
+
+static void *
+minstrel_ht_alloc(struct ieee80211_hw *hw, struct dentry *debugfsdir)
+{
+	return mac80211_minstrel.alloc(hw, debugfsdir);
+}
+
+static void
+minstrel_ht_free(void *priv)
+{
+	mac80211_minstrel.free(priv);
+}
+
+static struct rate_control_ops mac80211_minstrel_ht = {
+	.name = "minstrel_ht",
+	.tx_status = minstrel_ht_tx_status,
+	.get_rate = minstrel_ht_get_rate,
+	.rate_init = minstrel_ht_rate_init,
+	.rate_update = minstrel_ht_rate_update,
+	.alloc_sta = minstrel_ht_alloc_sta,
+	.free_sta = minstrel_ht_free_sta,
+	.alloc = minstrel_ht_alloc,
+	.free = minstrel_ht_free,
+#ifdef CPTCFG_MAC80211_DEBUGFS
+	.add_sta_debugfs = minstrel_ht_add_sta_debugfs,
+	.remove_sta_debugfs = minstrel_ht_remove_sta_debugfs,
+#endif
+};
+
+
+static void
+init_sample_table(void)
+{
+	int col, i, new_idx;
+	u8 rnd[MCS_GROUP_RATES];
+
+	memset(sample_table, 0xff, sizeof(sample_table));
+	for (col = 0; col < SAMPLE_COLUMNS; col++) {
+		for (i = 0; i < MCS_GROUP_RATES; i++) {
+			get_random_bytes(rnd, sizeof(rnd));
+			new_idx = (i + rnd[i]) % MCS_GROUP_RATES;
+
+			while (sample_table[col][new_idx] != 0xff)
+				new_idx = (new_idx + 1) % MCS_GROUP_RATES;
+
+			sample_table[col][new_idx] = i;
+		}
+	}
+}
+
+int __init
+rc80211_minstrel_ht_init(void)
+{
+	init_sample_table();
+	return ieee80211_rate_control_register(&mac80211_minstrel_ht);
+}
+
+void
+rc80211_minstrel_ht_exit(void)
+{
+	ieee80211_rate_control_unregister(&mac80211_minstrel_ht);
+}