rc80211_minstrel_ht.c 26.2 KB
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/*
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 * Copyright (C) 2010-2013 Felix Fietkau <nbd@openwrt.org>
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 *
 * 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
#define SAMPLE_COLUMNS	10
#define EWMA_LEVEL		75

/* 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))

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/* Transmission time (nanoseconds) for a packet containing (syms) symbols */
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#define MCS_SYMBOL_TIME(sgi, syms)					\
	(sgi ?								\
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	  ((syms) * 18000 + 4000) / 5 :	/* syms * 3.6 us */		\
	  ((syms) * 1000) << 2		/* syms * 4 us */		\
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	)

/* 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)))

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/*
 * Define group sort order: HT40 -> SGI -> #streams
 */
#define GROUP_IDX(_streams, _sgi, _ht40)	\
	MINSTREL_MAX_STREAMS * 2 * _ht40 +	\
	MINSTREL_MAX_STREAMS * _sgi +		\
	_streams - 1

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/* MCS rate information for an MCS group */
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#define MCS_GROUP(_streams, _sgi, _ht40)				\
	[GROUP_IDX(_streams, _sgi, _ht40)] = {				\
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	.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)		\
	}								\
}

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#define CCK_DURATION(_bitrate, _short, _len)		\
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	(1000 * (10 /* SIFS */ +			\
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	 (_short ? 72 + 24 : 144 + 48 ) +		\
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	 (8 * (_len + 4) * 10) / (_bitrate)))
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#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)			\
		}						\
	}

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/*
 * 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.
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 *
 * Sortorder has to be fixed for GROUP_IDX macro to be applicable:
 * HT40 -> SGI -> #streams
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 */
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
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	/* must be last */
	CCK_GROUP
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};

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#define MINSTREL_CCK_GROUP	(ARRAY_SIZE(minstrel_mcs_groups) - 1)

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static u8 sample_table[SAMPLE_COLUMNS][MCS_GROUP_RATES];

/*
 * Perform EWMA (Exponentially Weighted Moving Average) calculation
 */
static int
minstrel_ewma(int old, int new, int weight)
{
	return (new * (100 - weight) + old * weight) / 100;
}

/*
 * Look up an MCS group index based on mac80211 rate information
 */
static int
minstrel_ht_get_group_idx(struct ieee80211_tx_rate *rate)
{
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	return GROUP_IDX((rate->idx / MCS_GROUP_RATES) + 1,
			 !!(rate->flags & IEEE80211_TX_RC_SHORT_GI),
			 !!(rate->flags & IEEE80211_TX_RC_40_MHZ_WIDTH));
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}

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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];
}

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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
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minstrel_calc_rate_ewma(struct minstrel_rate_stats *mr)
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{
	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
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minstrel_ht_calc_tp(struct minstrel_ht_sta *mi, int group, int rate)
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{
	struct minstrel_rate_stats *mr;
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	unsigned int nsecs = 0;
	unsigned int tp;
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	mr = &mi->groups[group].rates[rate];

	if (mr->probability < MINSTREL_FRAC(1, 10)) {
		mr->cur_tp = 0;
		return;
	}

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	if (group != MINSTREL_CCK_GROUP)
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		nsecs = 1000 * mi->overhead / MINSTREL_TRUNC(mi->avg_ampdu_len);
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	nsecs += minstrel_mcs_groups[group].duration[rate];
	tp = 1000000 * ((mr->probability * 1000) / nsecs);

	mr->cur_tp = MINSTREL_TRUNC(tp);
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}

/*
 * 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;
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	int prob_max_streams = 1;
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	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;
	mi->max_tp_rate = 0;
	mi->max_tp_rate2 = 0;
	mi->max_prob_rate = 0;

	for (group = 0; group < ARRAY_SIZE(minstrel_mcs_groups); group++) {
		cur_prob = 0;
		cur_prob_tp = 0;
		cur_tp = 0;
		cur_tp2 = 0;

		mg = &mi->groups[group];
		if (!mg->supported)
			continue;

		mg->max_tp_rate = 0;
		mg->max_tp_rate2 = 0;
		mg->max_prob_rate = 0;
		mi->sample_count++;

		for (i = 0; i < MCS_GROUP_RATES; i++) {
			if (!(mg->supported & BIT(i)))
				continue;

			mr = &mg->rates[i];
			mr->retry_updated = false;
			index = MCS_GROUP_RATES * group + i;
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			minstrel_calc_rate_ewma(mr);
			minstrel_ht_calc_tp(mi, group, i);
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			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;
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				cur_prob_tp = mr->cur_tp;
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			}

			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;
			}
		}
	}

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	/* try to sample all available rates during each interval */
	mi->sample_count *= 8;
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	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) {
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			mi->max_tp_rate2 = mi->max_tp_rate;
			cur_tp2 = cur_tp;
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			mi->max_tp_rate = mg->max_tp_rate;
			cur_tp = mr->cur_tp;
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			prob_max_streams = minstrel_mcs_groups[group].streams - 1;
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		}

		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;
		}
	}

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	if (prob_max_streams < 1)
		prob_max_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 <= prob_max_streams) {
			mi->max_prob_rate = mg->max_prob_rate;
			cur_prob = mr->cur_prob;
			cur_prob_tp = mr->cur_tp;
		}
	}


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	mi->stats_update = jiffies;
}

static bool
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minstrel_ht_txstat_valid(struct minstrel_priv *mp, struct ieee80211_tx_rate *rate)
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{
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	if (rate->idx < 0)
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		return false;

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	if (!rate->count)
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		return false;

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	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];
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}

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
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minstrel_downgrade_rate(struct minstrel_ht_sta *mi, unsigned int *idx,
			bool primary)
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{
	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
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minstrel_aggr_check(struct ieee80211_sta *pubsta, struct sk_buff *skb)
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{
	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;
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	if (likely(sta->ampdu_mlme.tid_tx[tid]))
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		return;

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	if (skb_get_queue_mapping(skb) == IEEE80211_AC_VO)
		return;

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	ieee80211_start_tx_ba_session(pubsta, tid, 5000);
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}

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;
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	bool last;
	int i;
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	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;

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	if (!(info->flags & IEEE80211_TX_STAT_AMPDU)) {
		info->status.ampdu_ack_len =
			(info->flags & IEEE80211_TX_STAT_ACK ? 1 : 0);
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		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) {
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		mi->sample_wait = 16 + 2 * MINSTREL_TRUNC(mi->avg_ampdu_len);
		mi->sample_tries = 2;
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		mi->sample_count--;
	}

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	if (info->flags & IEEE80211_TX_CTL_RATE_CTRL_PROBE)
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		mi->sample_packets += info->status.ampdu_len;

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	last = !minstrel_ht_txstat_valid(mp, &ar[0]);
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	for (i = 0; !last; i++) {
		last = (i == IEEE80211_TX_MAX_RATES - 1) ||
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		       !minstrel_ht_txstat_valid(mp, &ar[i + 1]);
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		rate = minstrel_ht_get_stats(mp, mi, &ar[i]);
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		if (last)
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			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);

	rate2 = minstrel_get_ratestats(mi, mi->max_tp_rate2);
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	if (rate2->attempts > 30 &&
	    MINSTREL_FRAC(rate2->success, rate2->attempts) <
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	    MINSTREL_FRAC(20, 100))
		minstrel_downgrade_rate(mi, &mi->max_tp_rate2, false);

	if (time_after(jiffies, mi->stats_update + (mp->update_interval / 2 * HZ) / 1000)) {
		minstrel_ht_update_stats(mp, mi);
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		if (!(info->flags & IEEE80211_TX_CTL_AMPDU) &&
		    mi->max_prob_rate / MCS_GROUP_RATES != MINSTREL_CCK_GROUP)
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			minstrel_aggr_check(sta, skb);
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	}
}

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;
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	unsigned int ctime = 0;
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	unsigned int t_slot = 9; /* FIXME */
	unsigned int ampdu_len = MINSTREL_TRUNC(mi->avg_ampdu_len);
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	unsigned int overhead = 0, overhead_rtscts = 0;
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	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];
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	tx_time_data = group->duration[index % MCS_GROUP_RATES] * ampdu_len / 1000;
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	/* 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);

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	if (index / MCS_GROUP_RATES != MINSTREL_CCK_GROUP) {
		overhead = mi->overhead;
		overhead_rtscts = mi->overhead_rtscts;
	}

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	/* Total TX time for data and Contention after first 2 tries */
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	tx_time = ctime + 2 * (overhead + tx_time_data);
	tx_time_rtscts = ctime + 2 * (overhead_rtscts + tx_time_data);
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	/* See how many more tries we can fit inside segment size */
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	do {
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		/* Contention time for this try */
		ctime = (t_slot * cw) >> 1;
		cw = min((cw << 1) | 1, mp->cw_max);

		/* Total TX time after this try */
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		tx_time += ctime + overhead + tx_time_data;
		tx_time_rtscts += ctime + overhead_rtscts + tx_time_data;
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		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_tx_rate *rate, int index,
                     bool sample, bool rtscts)
{
	const struct mcs_group *group = &minstrel_mcs_groups[index / MCS_GROUP_RATES];
	struct minstrel_rate_stats *mr;

	mr = minstrel_get_ratestats(mi, index);
	if (!mr->retry_updated)
		minstrel_calc_retransmit(mp, mi, index);

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	if (sample)
		rate->count = 1;
	else if (mr->probability < MINSTREL_FRAC(20, 100))
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		rate->count = 2;
	else if (rtscts)
		rate->count = mr->retry_count_rtscts;
	else
		rate->count = mr->retry_count;

608
	rate->flags = 0;
609
	if (rtscts)
610
		rate->flags |= IEEE80211_TX_RC_USE_RTS_CTS;
611 612 613 614 615 616 617

	if (index / MCS_GROUP_RATES == MINSTREL_CCK_GROUP) {
		rate->idx = mp->cck_rates[index % ARRAY_SIZE(mp->cck_rates)];
		return;
	}

	rate->flags |= IEEE80211_TX_RC_MCS | group->flags;
618 619 620 621 622 623 624 625 626 627 628 629 630 631 632 633 634 635 636 637 638 639 640 641 642 643 644 645 646 647
	rate->idx = index % MCS_GROUP_RATES + (group->streams - 1) * MCS_GROUP_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;
	int sample_idx = 0;

	if (mi->sample_wait > 0) {
		mi->sample_wait--;
		return -1;
	}

	if (!mi->sample_tries)
		return -1;

	mi->sample_tries--;
	mg = &mi->groups[mi->sample_group];
	sample_idx = sample_table[mg->column][mg->index];
	mr = &mg->rates[sample_idx];
	sample_idx += mi->sample_group * MCS_GROUP_RATES;
648
	minstrel_next_sample_idx(mi);
649

650 651 652 653 654 655 656
	/*
	 * Sampling might add some overhead (RTS, no aggregation)
	 * to the frame. Hence, don't use sampling for the currently
	 * used max TP rate.
	 */
	if (sample_idx == mi->max_tp_rate)
		return -1;
657 658 659 660 661
	/*
	 * When not using MRR, do not sample if the probability is already
	 * higher than 95% to avoid wasting airtime
	 */
	if (!mp->has_mrr && (mr->probability > MINSTREL_FRAC(95, 100)))
662
		return -1;
663 664 665 666 667 668 669

	/*
	 * Make sure that lower rates get sampled only occasionally,
	 * if the link is working perfectly.
	 */
	if (minstrel_get_duration(sample_idx) >
	    minstrel_get_duration(mi->max_tp_rate)) {
670
		if (mr->sample_skipped < 20)
671
			return -1;
672 673

		if (mi->sample_slow++ > 2)
674
			return -1;
675 676 677 678 679
	}

	return sample_idx;
}

680 681 682 683 684 685 686 687 688 689 690 691 692 693 694 695
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;
}

696 697 698 699 700 701 702 703 704 705
static void
minstrel_ht_get_rate(void *priv, struct ieee80211_sta *sta, void *priv_sta,
                     struct ieee80211_tx_rate_control *txrc)
{
	struct ieee80211_tx_info *info = IEEE80211_SKB_CB(txrc->skb);
	struct ieee80211_tx_rate *ar = info->status.rates;
	struct minstrel_ht_sta_priv *msp = priv_sta;
	struct minstrel_ht_sta *mi = &msp->ht;
	struct minstrel_priv *mp = priv;
	int sample_idx;
706
	bool sample = false;
707 708 709 710 711 712 713 714

	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;
715
	minstrel_ht_check_cck_shortpreamble(mp, mi, txrc->short_preamble);
716 717 718 719 720 721 722

	/* 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);
723 724 725

#ifdef CONFIG_MAC80211_DEBUGFS
	/* use fixed index if set */
726 727 728 729 730 731
	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;
	}
732 733
#endif

734
	if (sample_idx >= 0) {
735
		sample = true;
736
		minstrel_ht_set_rate(mp, mi, &ar[0], sample_idx,
737
			true, false);
738 739 740
		info->flags |= IEEE80211_TX_CTL_RATE_CTRL_PROBE;
	} else {
		minstrel_ht_set_rate(mp, mi, &ar[0], mi->max_tp_rate,
741
			false, false);
742 743
	}

744 745 746 747 748 749 750 751
	if (mp->hw->max_rates >= 3) {
		/*
		 * At least 3 tx rates supported, use
		 * sample_rate -> max_tp_rate -> max_prob_rate for sampling and
		 * max_tp_rate -> max_tp_rate2 -> max_prob_rate by default.
		 */
		if (sample_idx >= 0)
			minstrel_ht_set_rate(mp, mi, &ar[1], mi->max_tp_rate,
752
				false, false);
753 754
		else
			minstrel_ht_set_rate(mp, mi, &ar[1], mi->max_tp_rate2,
755
				false, true);
756 757

		minstrel_ht_set_rate(mp, mi, &ar[2], mi->max_prob_rate,
758
				     false, !sample);
759 760 761 762 763 764 765 766 767 768

		ar[3].count = 0;
		ar[3].idx = -1;
	} else if (mp->hw->max_rates == 2) {
		/*
		 * Only 2 tx rates supported, use
		 * sample_rate -> max_prob_rate for sampling and
		 * max_tp_rate -> max_prob_rate by default.
		 */
		minstrel_ht_set_rate(mp, mi, &ar[1], mi->max_prob_rate,
769
				     false, !sample);
770 771 772 773 774 775 776 777

		ar[2].count = 0;
		ar[2].idx = -1;
	} else {
		/* Not using MRR, only use the first rate */
		ar[1].count = 0;
		ar[1].idx = -1;
	}
778 779 780 781 782 783 784 785 786 787

	mi->total_packets++;

	/* wraparound */
	if (mi->total_packets == ~0) {
		mi->total_packets = 0;
		mi->sample_packets = 0;
	}
}

788 789 790 791 792 793 794 795 796 797 798 799 800 801 802 803 804 805 806 807 808 809 810 811
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;

	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;
}

812 813
static void
minstrel_ht_update_caps(void *priv, struct ieee80211_supported_band *sband,
814
                        struct ieee80211_sta *sta, void *priv_sta)
815 816 817 818 819 820
{
	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;
821
	int n_supported = 0;
822 823 824 825 826
	int ack_dur;
	int stbc;
	int i;

	/* fall back to the old minstrel for legacy stations */
827 828
	if (!sta->ht_cap.ht_supported)
		goto use_legacy;
829 830

	BUILD_BUG_ON(ARRAY_SIZE(minstrel_mcs_groups) !=
831
		MINSTREL_MAX_STREAMS * MINSTREL_STREAM_GROUPS + 1);
832 833 834 835 836

	msp->is_ht = true;
	memset(mi, 0, sizeof(*mi));
	mi->stats_update = jiffies;

837 838
	ack_dur = ieee80211_frame_duration(sband->band, 10, 60, 1, 1);
	mi->overhead = ieee80211_frame_duration(sband->band, 0, 60, 1, 1) + ack_dur;
839 840 841 842 843 844 845 846 847 848 849 850 851 852 853 854 855 856 857 858 859 860 861
	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;
862 863 864 865 866
		if (i == MINSTREL_CCK_GROUP) {
			minstrel_ht_update_cck(mp, mi, sband, sta);
			continue;
		}

867
		if (minstrel_mcs_groups[i].flags & IEEE80211_TX_RC_SHORT_GI) {
868 869 870 871 872 873 874
			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;
			}
875 876
		}

877 878
		if (minstrel_mcs_groups[i].flags & IEEE80211_TX_RC_40_MHZ_WIDTH &&
		    sta->bandwidth < IEEE80211_STA_RX_BW_40)
879 880
			continue;

881
		/* Mark MCS > 7 as unsupported if STA is in static SMPS mode */
882
		if (sta->smps_mode == IEEE80211_SMPS_STATIC &&
883 884 885
		    minstrel_mcs_groups[i].streams > 1)
			continue;

886 887
		mi->groups[i].supported =
			mcs->rx_mask[minstrel_mcs_groups[i].streams - 1];
888 889 890

		if (mi->groups[i].supported)
			n_supported++;
891
	}
892 893 894 895 896 897 898 899 900 901 902 903

	if (!n_supported)
		goto use_legacy;

	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);
904 905 906 907 908 909
}

static void
minstrel_ht_rate_init(void *priv, struct ieee80211_supported_band *sband,
                      struct ieee80211_sta *sta, void *priv_sta)
{
910
	minstrel_ht_update_caps(priv, sband, sta, priv_sta);
911 912 913 914 915
}

static void
minstrel_ht_rate_update(void *priv, struct ieee80211_supported_band *sband,
                        struct ieee80211_sta *sta, void *priv_sta,
916
                        u32 changed)
917
{
918
	minstrel_ht_update_caps(priv, sband, sta, priv_sta);
919 920 921 922 923 924 925 926 927 928 929 930 931 932 933 934 935 936
}

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;
	}

937
	msp = kzalloc(sizeof(*msp), gfp);
938 939 940 941 942 943 944 945 946 947 948 949 950 951
	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:
952
	kfree(msp->ratelist);
953 954 955 956 957 958 959 960 961 962 963 964 965 966 967 968 969 970 971 972 973 974 975 976 977 978 979 980 981 982 983 984 985 986 987 988 989 990 991 992 993 994 995 996 997 998 999 1000 1001 1002 1003 1004 1005 1006 1007 1008 1009 1010 1011 1012 1013 1014 1015 1016 1017 1018 1019 1020 1021 1022 1023 1024 1025 1026 1027 1028
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 CONFIG_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);
}