rc80211_minstrel_ht.c 26.4 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;

	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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			mi->max_prob_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 (mi->max_prob_streams < 1)
		mi->max_prob_streams = 1;
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	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 &&
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		    minstrel_mcs_groups[group].streams <= mi->max_prob_streams) {
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			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];
552
	tx_time_data = group->duration[index % MCS_GROUP_RATES] * ampdu_len / 1000;
553
554
555
556
557
558
559

	/* 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);

560
561
562
563
564
	if (index / MCS_GROUP_RATES != MINSTREL_CCK_GROUP) {
		overhead = mi->overhead;
		overhead_rtscts = mi->overhead_rtscts;
	}

565
	/* Total TX time for data and Contention after first 2 tries */
566
567
	tx_time = ctime + 2 * (overhead + tx_time_data);
	tx_time_rtscts = ctime + 2 * (overhead_rtscts + tx_time_data);
568
569

	/* See how many more tries we can fit inside segment size */
570
	do {
571
572
573
574
575
		/* Contention time for this try */
		ctime = (t_slot * cw) >> 1;
		cw = min((cw << 1) | 1, mp->cw_max);

		/* Total TX time after this try */
576
577
		tx_time += ctime + overhead + tx_time_data;
		tx_time_rtscts += ctime + overhead_rtscts + tx_time_data;
578

579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
		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);

598
599
600
	if (sample)
		rate->count = 1;
	else if (mr->probability < MINSTREL_FRAC(20, 100))
601
602
603
604
605
606
		rate->count = 2;
	else if (rtscts)
		rate->count = mr->retry_count_rtscts;
	else
		rate->count = mr->retry_count;

607
	rate->flags = 0;
608
	if (rtscts)
609
		rate->flags |= IEEE80211_TX_RC_USE_RTS_CTS;
610
611
612
613
614
615
616

	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;
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
	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;
632
	unsigned int sample_dur, sample_group;
633
634
635
636
637
638
639
640
641
642
643
644
645
	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];
646
647
	sample_group = mi->sample_group;
	sample_idx += 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

	/*
	 * Make sure that lower rates get sampled only occasionally,
	 * if the link is working perfectly.
	 */
668
669
670
671
672
	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))) {
673
		if (mr->sample_skipped < 20)
674
			return -1;
675
676

		if (mi->sample_slow++ > 2)
677
			return -1;
678
	}
679
	mi->sample_tries--;
680
681
682
683

	return sample_idx;
}

684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
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;
}

700
701
702
703
704
705
706
707
708
709
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;
710
	bool sample = false;
711
712
713
714
715
716
717
718

	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;
719
	minstrel_ht_check_cck_shortpreamble(mp, mi, txrc->short_preamble);
720
721
722
723
724
725
726

	/* 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);
727
728
729

#ifdef CONFIG_MAC80211_DEBUGFS
	/* use fixed index if set */
730
731
732
733
734
735
	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;
	}
736
737
#endif

738
	if (sample_idx >= 0) {
739
		sample = true;
740
		minstrel_ht_set_rate(mp, mi, &ar[0], sample_idx,
741
			true, false);
742
743
744
		info->flags |= IEEE80211_TX_CTL_RATE_CTRL_PROBE;
	} else {
		minstrel_ht_set_rate(mp, mi, &ar[0], mi->max_tp_rate,
745
			false, false);
746
747
	}

748
749
750
751
752
753
754
755
	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,
756
				false, false);
757
758
		else
			minstrel_ht_set_rate(mp, mi, &ar[1], mi->max_tp_rate2,
759
				false, true);
760
761

		minstrel_ht_set_rate(mp, mi, &ar[2], mi->max_prob_rate,
762
				     false, !sample);
763
764
765
766
767
768
769
770
771
772

		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,
773
				     false, !sample);
774
775
776
777
778
779
780
781

		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;
	}
782
783
784
785
786
787
788
789
790
791

	mi->total_packets++;

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

792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
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;
}

816
817
static void
minstrel_ht_update_caps(void *priv, struct ieee80211_supported_band *sband,
818
                        struct ieee80211_sta *sta, void *priv_sta)
819
820
821
822
823
824
{
	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;
825
	int n_supported = 0;
826
827
828
829
830
	int ack_dur;
	int stbc;
	int i;

	/* fall back to the old minstrel for legacy stations */
831
832
	if (!sta->ht_cap.ht_supported)
		goto use_legacy;
833
834

	BUILD_BUG_ON(ARRAY_SIZE(minstrel_mcs_groups) !=
835
		MINSTREL_MAX_STREAMS * MINSTREL_STREAM_GROUPS + 1);
836
837
838
839
840

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

841
842
	ack_dur = ieee80211_frame_duration(sband->band, 10, 60, 1, 1);
	mi->overhead = ieee80211_frame_duration(sband->band, 0, 60, 1, 1) + ack_dur;
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
	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;
866
867
868
869
870
		if (i == MINSTREL_CCK_GROUP) {
			minstrel_ht_update_cck(mp, mi, sband, sta);
			continue;
		}

871
		if (minstrel_mcs_groups[i].flags & IEEE80211_TX_RC_SHORT_GI) {
872
873
874
875
876
877
878
			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;
			}
879
880
		}

881
882
		if (minstrel_mcs_groups[i].flags & IEEE80211_TX_RC_40_MHZ_WIDTH &&
		    sta->bandwidth < IEEE80211_STA_RX_BW_40)
883
884
			continue;

885
		/* Mark MCS > 7 as unsupported if STA is in static SMPS mode */
886
		if (sta->smps_mode == IEEE80211_SMPS_STATIC &&
887
888
889
		    minstrel_mcs_groups[i].streams > 1)
			continue;

890
891
		mi->groups[i].supported =
			mcs->rx_mask[minstrel_mcs_groups[i].streams - 1];
892
893
894

		if (mi->groups[i].supported)
			n_supported++;
895
	}
896
897
898
899
900
901
902
903
904
905
906
907

	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);
908
909
910
911
912
913
}

static void
minstrel_ht_rate_init(void *priv, struct ieee80211_supported_band *sband,
                      struct ieee80211_sta *sta, void *priv_sta)
{
914
	minstrel_ht_update_caps(priv, sband, sta, priv_sta);
915
916
917
918
919
}

static void
minstrel_ht_rate_update(void *priv, struct ieee80211_supported_band *sband,
                        struct ieee80211_sta *sta, void *priv_sta,
920
                        u32 changed)
921
{
922
	minstrel_ht_update_caps(priv, sband, sta, priv_sta);
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
}

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;
	}

941
	msp = kzalloc(sizeof(*msp), gfp);
942
943
944
945
946
947
948
949
950
951
952
953
954
955
	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:
956
	kfree(msp->ratelist);
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
1029
1030
1031
1032
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);
}