rc80211_minstrel_ht.c 27.7 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

/* 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];

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static void
minstrel_ht_update_rates(struct minstrel_priv *mp, struct minstrel_ht_sta *mi);

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/*
 * 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 / 8) + 1,
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			 !!(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);
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		idx = rate->idx % 8;
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	} 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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	unsigned int prob;
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	mr = &mi->groups[group].rates[rate];
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	prob = mr->probability;
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	if (prob < MINSTREL_FRAC(1, 10)) {
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		mr->cur_tp = 0;
		return;
	}

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	/*
	 * 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);

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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];
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	tp = 1000000 * ((prob * 1000) / nsecs);
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	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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	bool mi_rates_valid = false;
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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;

	for (group = 0; group < ARRAY_SIZE(minstrel_mcs_groups); group++) {
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		bool mg_rates_valid = false;

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		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;

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			index = MCS_GROUP_RATES * group + i;

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			/* 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 =
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						mi->max_prob_rate = index;
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					mi_rates_valid = true;
				}
				mg_rates_valid = true;
			}

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			mr = &mg->rates[i];
			mr->retry_updated = false;
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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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#ifdef CONFIG_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;
	}
#endif
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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;

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	if (unlikely(skb->protocol == cpu_to_be16(ETH_P_PAE)))
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		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, update = false;
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	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);
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		mi->sample_tries = 1;
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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) <
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	    MINSTREL_FRAC(20, 100)) {
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		minstrel_downgrade_rate(mi, &mi->max_tp_rate, true);
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		update = true;
	}
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	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)) {
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		minstrel_downgrade_rate(mi, &mi->max_tp_rate2, false);
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		update = true;
	}
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	if (time_after(jiffies, mi->stats_update + (mp->update_interval / 2 * HZ) / 1000)) {
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		update = true;
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		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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	}
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	if (update)
		minstrel_ht_update_rates(mp, mi);
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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;
605

606 607 608 609 610 611 612 613 614
		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,
615
                     struct ieee80211_sta_rates *ratetbl, int offset, int index)
616 617 618
{
	const struct mcs_group *group = &minstrel_mcs_groups[index / MCS_GROUP_RATES];
	struct minstrel_rate_stats *mr;
619 620
	u8 idx;
	u16 flags;
621 622 623 624 625

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

626 627 628 629 630 631 632 633 634
	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;
	}
635 636

	if (index / MCS_GROUP_RATES == MINSTREL_CCK_GROUP) {
637 638 639
		idx = mp->cck_rates[index % ARRAY_SIZE(mp->cck_rates)];
		flags = 0;
	} else {
640
		idx = index % MCS_GROUP_RATES + (group->streams - 1) * 8;
641 642 643 644 645 646 647 648 649 650 651 652 653 654 655 656 657 658 659 660
		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)
661
		return;
662 663 664 665 666 667 668 669 670 671 672 673 674

	/* 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);
675 676
	}

677 678
	rates->rate[i].idx = -1;
	rate_control_set_rates(mp->hw, mi->sta, rates);
679 680 681 682 683 684 685 686 687 688 689 690 691 692
}

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;
693
	unsigned int sample_dur, sample_group;
694 695 696 697 698 699 700 701 702 703
	int sample_idx = 0;

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

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

704 705
	sample_group = mi->sample_group;
	mg = &mi->groups[sample_group];
706
	sample_idx = sample_table[mg->column][mg->index];
707 708 709 710 711
	minstrel_next_sample_idx(mi);

	if (!(mg->supported & BIT(sample_idx)))
		return -1;

712
	mr = &mg->rates[sample_idx];
713
	sample_idx += sample_group * MCS_GROUP_RATES;
714

715 716 717
	/*
	 * Sampling might add some overhead (RTS, no aggregation)
	 * to the frame. Hence, don't use sampling for the currently
718
	 * used rates.
719
	 */
720 721 722
	if (sample_idx == mi->max_tp_rate ||
	    sample_idx == mi->max_tp_rate2 ||
	    sample_idx == mi->max_prob_rate)
723
		return -1;
724

725
	/*
726 727
	 * Do not sample if the probability is already higher than 95%
	 * to avoid wasting airtime.
728
	 */
729
	if (mr->probability > MINSTREL_FRAC(95, 100))
730
		return -1;
731 732 733 734 735

	/*
	 * Make sure that lower rates get sampled only occasionally,
	 * if the link is working perfectly.
	 */
736 737 738 739 740
	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))) {
741
		if (mr->sample_skipped < 20)
742
			return -1;
743 744

		if (mi->sample_slow++ > 2)
745
			return -1;
746
	}
747
	mi->sample_tries--;
748 749 750 751

	return sample_idx;
}

752 753 754 755 756 757 758 759 760 761 762 763 764 765 766 767
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;
}

768 769 770 771
static void
minstrel_ht_get_rate(void *priv, struct ieee80211_sta *sta, void *priv_sta,
                     struct ieee80211_tx_rate_control *txrc)
{
772
	const struct mcs_group *sample_group;
773
	struct ieee80211_tx_info *info = IEEE80211_SKB_CB(txrc->skb);
774
	struct ieee80211_tx_rate *rate = &info->status.rates[0];
775 776 777 778 779 780 781 782 783 784 785 786
	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;
787
	minstrel_ht_check_cck_shortpreamble(mp, mi, txrc->short_preamble);
788

789 790 791 792 793
#ifdef CONFIG_MAC80211_DEBUGFS
	if (mp->fixed_rate_idx != -1)
		return;
#endif

794 795
	/* Don't use EAPOL frames for sampling on non-mrr hw */
	if (mp->hw->max_rates == 1 &&
796
	    (info->control.flags & IEEE80211_TX_CTRL_PORT_CTRL_PROTO))
797 798 799
		sample_idx = -1;
	else
		sample_idx = minstrel_get_sample_rate(mp, mi);
800

801 802 803 804 805 806 807
	mi->total_packets++;

	/* wraparound */
	if (mi->total_packets == ~0) {
		mi->total_packets = 0;
		mi->sample_packets = 0;
	}
808 809 810 811 812 813

	if (sample_idx < 0)
		return;

	sample_group = &minstrel_mcs_groups[sample_idx / MCS_GROUP_RATES];
	info->flags |= IEEE80211_TX_CTL_RATE_CTRL_PROBE;
814 815 816 817 818 819 820 821 822
	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;
	}

823
	rate->idx = sample_idx % MCS_GROUP_RATES +
824
		    (sample_group->streams - 1) * 8;
825
	rate->flags = IEEE80211_TX_RC_MCS | sample_group->flags;
826 827
}

828 829 830 831 832 833 834 835 836 837
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;

838 839 840
	if (!(mp->hw->flags & IEEE80211_HW_SUPPORTS_HT_CCK_RATES))
		return;

841 842 843 844 845 846 847 848 849 850 851 852 853 854
	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;
}

855 856
static void
minstrel_ht_update_caps(void *priv, struct ieee80211_supported_band *sband,
857
			struct cfg80211_chan_def *chandef,
858
                        struct ieee80211_sta *sta, void *priv_sta)
859 860 861 862 863 864
{
	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;
865
	int n_supported = 0;
866 867 868 869 870
	int ack_dur;
	int stbc;
	int i;

	/* fall back to the old minstrel for legacy stations */
871 872
	if (!sta->ht_cap.ht_supported)
		goto use_legacy;
873 874

	BUILD_BUG_ON(ARRAY_SIZE(minstrel_mcs_groups) !=
875
		MINSTREL_MAX_STREAMS * MINSTREL_STREAM_GROUPS + 1);
876 877 878

	msp->is_ht = true;
	memset(mi, 0, sizeof(*mi));
879 880

	mi->sta = sta;
881 882
	mi->stats_update = jiffies;

883 884 885
	ack_dur = ieee80211_frame_duration(sband->band, 10, 60, 1, 1, 0);
	mi->overhead = ieee80211_frame_duration(sband->band, 0, 60, 1, 1, 0);
	mi->overhead += ack_dur;
886 887 888 889 890 891 892 893 894 895 896 897 898 899 900 901 902 903 904 905 906 907 908
	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;
909 910 911 912 913
		if (i == MINSTREL_CCK_GROUP) {
			minstrel_ht_update_cck(mp, mi, sband, sta);
			continue;
		}

914
		if (minstrel_mcs_groups[i].flags & IEEE80211_TX_RC_SHORT_GI) {
915 916 917 918 919 920 921
			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;
			}
922 923
		}

924 925
		if (minstrel_mcs_groups[i].flags & IEEE80211_TX_RC_40_MHZ_WIDTH &&
		    sta->bandwidth < IEEE80211_STA_RX_BW_40)
926 927
			continue;

928
		/* Mark MCS > 7 as unsupported if STA is in static SMPS mode */
929
		if (sta->smps_mode == IEEE80211_SMPS_STATIC &&
930 931 932
		    minstrel_mcs_groups[i].streams > 1)
			continue;

933 934
		mi->groups[i].supported =
			mcs->rx_mask[minstrel_mcs_groups[i].streams - 1];
935 936 937

		if (mi->groups[i].supported)
			n_supported++;
938
	}
939 940 941 942

	if (!n_supported)
		goto use_legacy;

943
	/* create an initial rate table with the lowest supported rates */
944
	minstrel_ht_update_stats(mp, mi);
945
	minstrel_ht_update_rates(mp, mi);
946

947 948 949 950 951 952 953
	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;
954 955
	return mac80211_minstrel.rate_init(priv, sband, chandef, sta,
					   &msp->legacy);
956 957 958 959
}

static void
minstrel_ht_rate_init(void *priv, struct ieee80211_supported_band *sband,
960
		      struct cfg80211_chan_def *chandef,
961 962
                      struct ieee80211_sta *sta, void *priv_sta)
{
963
	minstrel_ht_update_caps(priv, sband, chandef, sta, priv_sta);
964 965 966 967
}

static void
minstrel_ht_rate_update(void *priv, struct ieee80211_supported_band *sband,
968
			struct cfg80211_chan_def *chandef,
969
                        struct ieee80211_sta *sta, void *priv_sta,
970
                        u32 changed)
971
{
972
	minstrel_ht_update_caps(priv, sband, chandef, sta, priv_sta);
973 974 975 976 977 978 979 980 981 982 983 984 985 986 987 988 989 990
}

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;
	}

991
	msp = kzalloc(sizeof(*msp), gfp);
992 993 994 995 996 997 998 999 1000 1001 1002 1003 1004 1005
	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:
1006
	kfree(msp->ratelist);
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 1033 1034 1035 1036 1037 1038 1039 1040 1041 1042 1043 1044 1045 1046 1047 1048 1049 1050 1051 1052 1053 1054 1055 1056 1057 1058
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++) {
1059
		prandom_bytes(rnd, sizeof(rnd));
1060 1061 1062 1063 1064 1065 1066 1067 1068 1069 1070 1071 1072 1073 1074 1075 1076 1077 1078 1079 1080 1081
		for (i = 0; i < MCS_GROUP_RATES; i++) {
			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);
}