[mirror_ubuntu-zesty-kernel.git] / net / mac80211 / rc80211_minstrel.c

/*
 * Copyright (C) 2008 Felix Fietkau <nbd@openwrt.org>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 *
 * Based on minstrel.c:
 *   Copyright (C) 2005-2007 Derek Smithies <derek@indranet.co.nz>
 *   Sponsored by Indranet Technologies Ltd
 *
 * Based on sample.c:
 *   Copyright (c) 2005 John Bicket
 *   All rights reserved.
 *
 *   Redistribution and use in source and binary forms, with or without
 *   modification, are permitted provided that the following conditions
 *   are met:
 *   1. Redistributions of source code must retain the above copyright
 *      notice, this list of conditions and the following disclaimer,
 *      without modification.
 *   2. Redistributions in binary form must reproduce at minimum a disclaimer
 *      similar to the "NO WARRANTY" disclaimer below ("Disclaimer") and any
 *      redistribution must be conditioned upon including a substantially
 *      similar Disclaimer requirement for further binary redistribution.
 *   3. Neither the names of the above-listed copyright holders nor the names
 *      of any contributors may be used to endorse or promote products derived
 *      from this software without specific prior written permission.
 *
 *   Alternatively, this software may be distributed under the terms of the
 *   GNU General Public License ("GPL") version 2 as published by the Free
 *   Software Foundation.
 *
 *   NO WARRANTY
 *   THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 *   ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 *   LIMITED TO, THE IMPLIED WARRANTIES OF NONINFRINGEMENT, MERCHANTIBILITY
 *   AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL
 *   THE COPYRIGHT HOLDERS OR CONTRIBUTORS BE LIABLE FOR SPECIAL, EXEMPLARY,
 *   OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 *   SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 *   INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER
 *   IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 *   ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF
 *   THE POSSIBILITY OF SUCH DAMAGES.
 */
#include <linux/netdevice.h>
#include <linux/types.h>
#include <linux/skbuff.h>
#include <linux/debugfs.h>
#include <linux/random.h>
#include <linux/ieee80211.h>
#include <linux/slab.h>
#include <net/mac80211.h>
#include "rate.h"
#include "rc80211_minstrel.h"

#define SAMPLE_COLUMNS	10
#define SAMPLE_TBL(_mi, _idx, _col) \
		_mi->sample_table[(_idx * SAMPLE_COLUMNS) + _col]

/* convert mac80211 rate index to local array index */
static inline int
rix_to_ndx(struct minstrel_sta_info *mi, int rix)
{
	int i = rix;
	for (i = rix; i >= 0; i--)
		if (mi->r[i].rix == rix)
			break;
	return i;
}

static void
minstrel_update_stats(struct minstrel_priv *mp, struct minstrel_sta_info *mi)
{
	u32 max_tp = 0, index_max_tp = 0, index_max_tp2 = 0;
	u32 max_prob = 0, index_max_prob = 0;
	u32 usecs;
	int i;

	mi->stats_update = jiffies;
	for (i = 0; i < mi->n_rates; i++) {
		struct minstrel_rate *mr = &mi->r[i];

		usecs = mr->perfect_tx_time;
		if (!usecs)
			usecs = 1000000;

		if (mr->attempts) {
			mr->cur_prob = MINSTREL_FRAC(mr->success, mr->attempts);
			mr->succ_hist += mr->success;
			mr->att_hist += mr->attempts;
			mr->probability = minstrel_ewma(mr->probability,
							mr->cur_prob,
							EWMA_LEVEL);
			mr->cur_tp = mr->probability * (1000000 / usecs);
		}

		mr->last_success = mr->success;
		mr->last_attempts = mr->attempts;
		mr->success = 0;
		mr->attempts = 0;

		/* Sample less often below the 10% chance of success.
		 * Sample less often above the 95% chance of success. */
		if (mr->probability > MINSTREL_FRAC(95, 100) ||
		    mr->probability < MINSTREL_FRAC(10, 100)) {
			mr->adjusted_retry_count = mr->retry_count >> 1;
			if (mr->adjusted_retry_count > 2)
				mr->adjusted_retry_count = 2;
			mr->sample_limit = 4;
		} else {
			mr->sample_limit = -1;
			mr->adjusted_retry_count = mr->retry_count;
		}
		if (!mr->adjusted_retry_count)
			mr->adjusted_retry_count = 2;
	}

	for (i = 0; i < mi->n_rates; i++) {
		struct minstrel_rate *mr = &mi->r[i];
		if (max_tp < mr->cur_tp) {
			index_max_tp = i;
			max_tp = mr->cur_tp;
		}
		if (max_prob < mr->probability) {
			index_max_prob = i;
			max_prob = mr->probability;
		}
	}

	max_tp = 0;
	for (i = 0; i < mi->n_rates; i++) {
		struct minstrel_rate *mr = &mi->r[i];

		if (i == index_max_tp)
			continue;

		if (max_tp < mr->cur_tp) {
			index_max_tp2 = i;
			max_tp = mr->cur_tp;
		}
	}
	mi->max_tp_rate = index_max_tp;
	mi->max_tp_rate2 = index_max_tp2;
	mi->max_prob_rate = index_max_prob;
}

static void
minstrel_tx_status(void *priv, struct ieee80211_supported_band *sband,
                   struct ieee80211_sta *sta, void *priv_sta,
		   struct sk_buff *skb)
{
	struct minstrel_priv *mp = priv;
	struct minstrel_sta_info *mi = priv_sta;
	struct ieee80211_tx_info *info = IEEE80211_SKB_CB(skb);
	struct ieee80211_tx_rate *ar = info->status.rates;
	int i, ndx;
	int success;

	success = !!(info->flags & IEEE80211_TX_STAT_ACK);

	for (i = 0; i < IEEE80211_TX_MAX_RATES; i++) {
		if (ar[i].idx < 0)
			break;

		ndx = rix_to_ndx(mi, ar[i].idx);
		if (ndx < 0)
			continue;

		mi->r[ndx].attempts += ar[i].count;

		if ((i != IEEE80211_TX_MAX_RATES - 1) && (ar[i + 1].idx < 0))
			mi->r[ndx].success += success;
	}

	if ((info->flags & IEEE80211_TX_CTL_RATE_CTRL_PROBE) && (i >= 0))
		mi->sample_count++;

	if (mi->sample_deferred > 0)
		mi->sample_deferred--;

	if (time_after(jiffies, mi->stats_update +
				(mp->update_interval * HZ) / 1000))
		minstrel_update_stats(mp, mi);
}


static inline unsigned int
minstrel_get_retry_count(struct minstrel_rate *mr,
                         struct ieee80211_tx_info *info)
{
	unsigned int retry = mr->adjusted_retry_count;

	if (info->control.rates[0].flags & IEEE80211_TX_RC_USE_RTS_CTS)
		retry = max(2U, min(mr->retry_count_rtscts, retry));
	else if (info->control.rates[0].flags & IEEE80211_TX_RC_USE_CTS_PROTECT)
		retry = max(2U, min(mr->retry_count_cts, retry));
	return retry;
}


static int
minstrel_get_next_sample(struct minstrel_sta_info *mi)
{
	unsigned int sample_ndx;
	sample_ndx = SAMPLE_TBL(mi, mi->sample_idx, mi->sample_column);
	mi->sample_idx++;
	if ((int) mi->sample_idx > (mi->n_rates - 2)) {
		mi->sample_idx = 0;
		mi->sample_column++;
		if (mi->sample_column >= SAMPLE_COLUMNS)
			mi->sample_column = 0;
	}
	return sample_ndx;
}

static void
minstrel_get_rate(void *priv, struct ieee80211_sta *sta,
		  void *priv_sta, struct ieee80211_tx_rate_control *txrc)
{
	struct sk_buff *skb = txrc->skb;
	struct ieee80211_tx_info *info = IEEE80211_SKB_CB(skb);
	struct minstrel_sta_info *mi = priv_sta;
	struct minstrel_priv *mp = priv;
	struct ieee80211_tx_rate *ar = info->control.rates;
	unsigned int ndx, sample_ndx = 0;
	bool mrr;
	bool sample_slower = false;
	bool sample = false;
	int i, delta;
	int mrr_ndx[3];
	int sample_rate;

	if (rate_control_send_low(sta, priv_sta, txrc))
		return;

	mrr = mp->has_mrr && !txrc->rts && !txrc->bss_conf->use_cts_prot;

	ndx = mi->max_tp_rate;

	if (mrr)
		sample_rate = mp->lookaround_rate_mrr;
	else
		sample_rate = mp->lookaround_rate;

	mi->packet_count++;
	delta = (mi->packet_count * sample_rate / 100) -
			(mi->sample_count + mi->sample_deferred / 2);

	/* delta > 0: sampling required */
	if ((delta > 0) && (mrr || !mi->prev_sample)) {
		struct minstrel_rate *msr;
		if (mi->packet_count >= 10000) {
			mi->sample_deferred = 0;
			mi->sample_count = 0;
			mi->packet_count = 0;
		} else if (delta > mi->n_rates * 2) {
			/* With multi-rate retry, not every planned sample
			 * attempt actually gets used, due to the way the retry
			 * chain is set up - [max_tp,sample,prob,lowest] for
			 * sample_rate < max_tp.
			 *
			 * If there's too much sampling backlog and the link
			 * starts getting worse, minstrel would start bursting
			 * out lots of sampling frames, which would result
			 * in a large throughput loss. */
			mi->sample_count += (delta - mi->n_rates * 2);
		}

		sample_ndx = minstrel_get_next_sample(mi);
		msr = &mi->r[sample_ndx];
		sample = true;
		sample_slower = mrr && (msr->perfect_tx_time >
			mi->r[ndx].perfect_tx_time);

		if (!sample_slower) {
			if (msr->sample_limit != 0) {
				ndx = sample_ndx;
				mi->sample_count++;
				if (msr->sample_limit > 0)
					msr->sample_limit--;
			} else {
				sample = false;
			}
		} else {
			/* Only use IEEE80211_TX_CTL_RATE_CTRL_PROBE to mark
			 * packets that have the sampling rate deferred to the
			 * second MRR stage. Increase the sample counter only
			 * if the deferred sample rate was actually used.
			 * Use the sample_deferred counter to make sure that
			 * the sampling is not done in large bursts */
			info->flags |= IEEE80211_TX_CTL_RATE_CTRL_PROBE;
			mi->sample_deferred++;
		}
	}
	mi->prev_sample = sample;

	/* If we're not using MRR and the sampling rate already
	 * has a probability of >95%, we shouldn't be attempting
	 * to use it, as this only wastes precious airtime */
	if (!mrr && sample && (mi->r[ndx].probability > MINSTREL_FRAC(95, 100)))
		ndx = mi->max_tp_rate;

	ar[0].idx = mi->r[ndx].rix;
	ar[0].count = minstrel_get_retry_count(&mi->r[ndx], info);

	if (!mrr) {
		if (!sample)
			ar[0].count = mp->max_retry;
		ar[1].idx = mi->lowest_rix;
		ar[1].count = mp->max_retry;
		return;
	}

	/* MRR setup */
	if (sample) {
		if (sample_slower)
			mrr_ndx[0] = sample_ndx;
		else
			mrr_ndx[0] = mi->max_tp_rate;
	} else {
		mrr_ndx[0] = mi->max_tp_rate2;
	}
	mrr_ndx[1] = mi->max_prob_rate;
	mrr_ndx[2] = 0;
	for (i = 1; i < 4; i++) {
		ar[i].idx = mi->r[mrr_ndx[i - 1]].rix;
		ar[i].count = mi->r[mrr_ndx[i - 1]].adjusted_retry_count;
	}
}


static void
calc_rate_durations(enum ieee80211_band band,
		    struct minstrel_rate *d,
		    struct ieee80211_rate *rate)
{
	int erp = !!(rate->flags & IEEE80211_RATE_ERP_G);

	d->perfect_tx_time = ieee80211_frame_duration(band, 1200,
			rate->bitrate, erp, 1);
	d->ack_time = ieee80211_frame_duration(band, 10,
			rate->bitrate, erp, 1);
}

static void
init_sample_table(struct minstrel_sta_info *mi)
{
	unsigned int i, col, new_idx;
	unsigned int n_srates = mi->n_rates - 1;
	u8 rnd[8];

	mi->sample_column = 0;
	mi->sample_idx = 0;
	memset(mi->sample_table, 0, SAMPLE_COLUMNS * mi->n_rates);

	for (col = 0; col < SAMPLE_COLUMNS; col++) {
		for (i = 0; i < n_srates; i++) {
			get_random_bytes(rnd, sizeof(rnd));
			new_idx = (i + rnd[i & 7]) % n_srates;

			while (SAMPLE_TBL(mi, new_idx, col) != 0)
				new_idx = (new_idx + 1) % n_srates;

			/* Don't sample the slowest rate (i.e. slowest base
			 * rate). We must presume that the slowest rate works
			 * fine, or else other management frames will also be
			 * failing and the link will break */
			SAMPLE_TBL(mi, new_idx, col) = i + 1;
		}
	}
}

static void
minstrel_rate_init(void *priv, struct ieee80211_supported_band *sband,
               struct ieee80211_sta *sta, void *priv_sta)
{
	struct minstrel_sta_info *mi = priv_sta;
	struct minstrel_priv *mp = priv;
	struct ieee80211_rate *ctl_rate;
	unsigned int i, n = 0;
	unsigned int t_slot = 9; /* FIXME: get real slot time */

	mi->lowest_rix = rate_lowest_index(sband, sta);
	ctl_rate = &sband->bitrates[mi->lowest_rix];
	mi->sp_ack_dur = ieee80211_frame_duration(sband->band, 10,
				ctl_rate->bitrate,
				!!(ctl_rate->flags & IEEE80211_RATE_ERP_G), 1);

	for (i = 0; i < sband->n_bitrates; i++) {
		struct minstrel_rate *mr = &mi->r[n];
		unsigned int tx_time = 0, tx_time_cts = 0, tx_time_rtscts = 0;
		unsigned int tx_time_single;
		unsigned int cw = mp->cw_min;

		if (!rate_supported(sta, sband->band, i))
			continue;
		n++;
		memset(mr, 0, sizeof(*mr));

		mr->rix = i;
		mr->bitrate = sband->bitrates[i].bitrate / 5;
		calc_rate_durations(sband->band, mr, &sband->bitrates[i]);

		/* calculate maximum number of retransmissions before
		 * fallback (based on maximum segment size) */
		mr->sample_limit = -1;
		mr->retry_count = 1;
		mr->retry_count_cts = 1;
		mr->retry_count_rtscts = 1;
		tx_time = mr->perfect_tx_time + mi->sp_ack_dur;
		do {
			/* add one retransmission */
			tx_time_single = mr->ack_time + mr->perfect_tx_time;

			/* contention window */
			tx_time_single += (t_slot * cw) >> 1;
			cw = min((cw << 1) | 1, mp->cw_max);

			tx_time += tx_time_single;
			tx_time_cts += tx_time_single + mi->sp_ack_dur;
			tx_time_rtscts += tx_time_single + 2 * mi->sp_ack_dur;
			if ((tx_time_cts < mp->segment_size) &&
				(mr->retry_count_cts < mp->max_retry))
				mr->retry_count_cts++;
			if ((tx_time_rtscts < mp->segment_size) &&
				(mr->retry_count_rtscts < mp->max_retry))
				mr->retry_count_rtscts++;
		} while ((tx_time < mp->segment_size) &&
				(++mr->retry_count < mp->max_retry));
		mr->adjusted_retry_count = mr->retry_count;
	}

	for (i = n; i < sband->n_bitrates; i++) {
		struct minstrel_rate *mr = &mi->r[i];
		mr->rix = -1;
	}

	mi->n_rates = n;
	mi->stats_update = jiffies;

	init_sample_table(mi);
}

static void *
minstrel_alloc_sta(void *priv, struct ieee80211_sta *sta, gfp_t gfp)
{
	struct ieee80211_supported_band *sband;
	struct minstrel_sta_info *mi;
	struct minstrel_priv *mp = priv;
	struct ieee80211_hw *hw = mp->hw;
	int max_rates = 0;
	int i;

	mi = kzalloc(sizeof(struct minstrel_sta_info), gfp);
	if (!mi)
		return NULL;

	for (i = 0; i < IEEE80211_NUM_BANDS; i++) {
		sband = hw->wiphy->bands[i];
		if (sband && sband->n_bitrates > max_rates)
			max_rates = sband->n_bitrates;
	}

	mi->r = kzalloc(sizeof(struct minstrel_rate) * max_rates, gfp);
	if (!mi->r)
		goto error;

	mi->sample_table = kmalloc(SAMPLE_COLUMNS * max_rates, gfp);
	if (!mi->sample_table)
		goto error1;

	mi->stats_update = jiffies;
	return mi;

error1:
	kfree(mi->r);
error:
	kfree(mi);
	return NULL;
}

static void
minstrel_free_sta(void *priv, struct ieee80211_sta *sta, void *priv_sta)
{
	struct minstrel_sta_info *mi = priv_sta;

	kfree(mi->sample_table);
	kfree(mi->r);
	kfree(mi);
}

static void
minstrel_init_cck_rates(struct minstrel_priv *mp)
{
	static const int bitrates[4] = { 10, 20, 55, 110 };
	struct ieee80211_supported_band *sband;
	int i, j;

	sband = mp->hw->wiphy->bands[IEEE80211_BAND_2GHZ];
	if (!sband)
		return;

	for (i = 0, j = 0; i < sband->n_bitrates; i++) {
		struct ieee80211_rate *rate = &sband->bitrates[i];

		if (rate->flags & IEEE80211_RATE_ERP_G)
			continue;

		for (j = 0; j < ARRAY_SIZE(bitrates); j++) {
			if (rate->bitrate != bitrates[j])
				continue;

			mp->cck_rates[j] = i;
			break;
		}
	}
}

static void *
minstrel_alloc(struct ieee80211_hw *hw, struct dentry *debugfsdir)
{
	struct minstrel_priv *mp;

	mp = kzalloc(sizeof(struct minstrel_priv), GFP_ATOMIC);
	if (!mp)
		return NULL;

	/* contention window settings
	 * Just an approximation. Using the per-queue values would complicate
	 * the calculations and is probably unnecessary */
	mp->cw_min = 15;
	mp->cw_max = 1023;

	/* number of packets (in %) to use for sampling other rates
	 * sample less often for non-mrr packets, because the overhead
	 * is much higher than with mrr */
	mp->lookaround_rate = 5;
	mp->lookaround_rate_mrr = 10;

	/* maximum time that the hw is allowed to stay in one MRR segment */
	mp->segment_size = 6000;

	if (hw->max_rate_tries > 0)
		mp->max_retry = hw->max_rate_tries;
	else
		/* safe default, does not necessarily have to match hw properties */
		mp->max_retry = 7;

	if (hw->max_rates >= 4)
		mp->has_mrr = true;

	mp->hw = hw;
	mp->update_interval = 100;

#ifdef CONFIG_MAC80211_DEBUGFS
	mp->fixed_rate_idx = (u32) -1;
	mp->dbg_fixed_rate = debugfs_create_u32("fixed_rate_idx",
			S_IRUGO | S_IWUGO, debugfsdir, &mp->fixed_rate_idx);
#endif

	minstrel_init_cck_rates(mp);

	return mp;
}

static void
minstrel_free(void *priv)
{
#ifdef CONFIG_MAC80211_DEBUGFS
	debugfs_remove(((struct minstrel_priv *)priv)->dbg_fixed_rate);
#endif
	kfree(priv);
}

struct rate_control_ops mac80211_minstrel = {
	.name = "minstrel",
	.tx_status = minstrel_tx_status,
	.get_rate = minstrel_get_rate,
	.rate_init = minstrel_rate_init,
	.alloc = minstrel_alloc,
	.free = minstrel_free,
	.alloc_sta = minstrel_alloc_sta,
	.free_sta = minstrel_free_sta,
#ifdef CONFIG_MAC80211_DEBUGFS
	.add_sta_debugfs = minstrel_add_sta_debugfs,
	.remove_sta_debugfs = minstrel_remove_sta_debugfs,
#endif
};

int __init
rc80211_minstrel_init(void)
{
	return ieee80211_rate_control_register(&mac80211_minstrel);
}

void
rc80211_minstrel_exit(void)
{
	ieee80211_rate_control_unregister(&mac80211_minstrel);
}
Commit	Line	Data
cccf129f FF	1	/*
	2	* Copyright (C) 2008 Felix Fietkau <nbd@openwrt.org>
	3	*
	4	* This program is free software; you can redistribute it and/or modify
	5	* it under the terms of the GNU General Public License version 2 as
	6	* published by the Free Software Foundation.
	7	*
	8	* Based on minstrel.c:
	9	* Copyright (C) 2005-2007 Derek Smithies <derek@indranet.co.nz>
	10	* Sponsored by Indranet Technologies Ltd
	11	*
	12	* Based on sample.c:
	13	* Copyright (c) 2005 John Bicket
	14	* All rights reserved.
	15	*
	16	* Redistribution and use in source and binary forms, with or without
	17	* modification, are permitted provided that the following conditions
	18	* are met:
	19	* 1. Redistributions of source code must retain the above copyright
	20	* notice, this list of conditions and the following disclaimer,
	21	* without modification.
	22	* 2. Redistributions in binary form must reproduce at minimum a disclaimer
	23	* similar to the "NO WARRANTY" disclaimer below ("Disclaimer") and any
	24	* redistribution must be conditioned upon including a substantially
	25	* similar Disclaimer requirement for further binary redistribution.
	26	* 3. Neither the names of the above-listed copyright holders nor the names
	27	* of any contributors may be used to endorse or promote products derived
	28	* from this software without specific prior written permission.
	29	*
	30	* Alternatively, this software may be distributed under the terms of the
	31	* GNU General Public License ("GPL") version 2 as published by the Free
	32	* Software Foundation.
	33	*
	34	* NO WARRANTY
	35	* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
	36	* ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
	37	* LIMITED TO, THE IMPLIED WARRANTIES OF NONINFRINGEMENT, MERCHANTIBILITY
	38	* AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL
	39	* THE COPYRIGHT HOLDERS OR CONTRIBUTORS BE LIABLE FOR SPECIAL, EXEMPLARY,
	40	* OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
	41	* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
	42	* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER
	43	* IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
	44	* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF
	45	* THE POSSIBILITY OF SUCH DAMAGES.
	46	*/
	47	#include <linux/netdevice.h>
	48	#include <linux/types.h>
	49	#include <linux/skbuff.h>
	50	#include <linux/debugfs.h>
	51	#include <linux/random.h>
	52	#include <linux/ieee80211.h>
5a0e3ad6	53	#include <linux/slab.h>
cccf129f FF	54	#include <net/mac80211.h>
	55	#include "rate.h"
	56	#include "rc80211_minstrel.h"
	57
	58	#define SAMPLE_COLUMNS 10
	59	#define SAMPLE_TBL(_mi, _idx, _col) \
	60	_mi->sample_table[(_idx * SAMPLE_COLUMNS) + _col]
	61
	62	/* convert mac80211 rate index to local array index */
	63	static inline int
	64	rix_to_ndx(struct minstrel_sta_info *mi, int rix)
	65	{
	66	int i = rix;
	67	for (i = rix; i >= 0; i--)
	68	if (mi->r[i].rix == rix)
	69	break;
cccf129f FF	70	return i;
	71	}
	72
cccf129f FF	73	static void
	74	minstrel_update_stats(struct minstrel_priv mp, struct minstrel_sta_info mi)
	75	{
	76	u32 max_tp = 0, index_max_tp = 0, index_max_tp2 = 0;
	77	u32 max_prob = 0, index_max_prob = 0;
	78	u32 usecs;
cccf129f FF	79	int i;
	80
	81	mi->stats_update = jiffies;
	82	for (i = 0; i < mi->n_rates; i++) {
	83	struct minstrel_rate *mr = &mi->r[i];
	84
	85	usecs = mr->perfect_tx_time;
	86	if (!usecs)
	87	usecs = 1000000;
	88
cccf129f	89	if (mr->attempts) {
c8ca8c2f	90	mr->cur_prob = MINSTREL_FRAC(mr->success, mr->attempts);
cccf129f FF	91	mr->succ_hist += mr->success;
cccf129f FF	92	mr->att_hist += mr->attempts;
a512d4b5 TH	93	mr->probability = minstrel_ewma(mr->probability,
	94	mr->cur_prob,
	95	EWMA_LEVEL);
	96	mr->cur_tp = mr->probability * (1000000 / usecs);
cccf129f FF	97	}
	98
	99	mr->last_success = mr->success;
	100	mr->last_attempts = mr->attempts;
	101	mr->success = 0;
	102	mr->attempts = 0;
	103
	104	/* Sample less often below the 10% chance of success.
	105	* Sample less often above the 95% chance of success. */
c8ca8c2f TH	106	if (mr->probability > MINSTREL_FRAC(95, 100) \|\|
c8ca8c2f TH	107	mr->probability < MINSTREL_FRAC(10, 100)) {
cccf129f FF	108	mr->adjusted_retry_count = mr->retry_count >> 1;
	109	if (mr->adjusted_retry_count > 2)
	110	mr->adjusted_retry_count = 2;
f4a8cd94	111	mr->sample_limit = 4;
cccf129f	112	} else {
f4a8cd94	113	mr->sample_limit = -1;
cccf129f FF	114	mr->adjusted_retry_count = mr->retry_count;
	115	}
	116	if (!mr->adjusted_retry_count)
	117	mr->adjusted_retry_count = 2;
	118	}
	119
	120	for (i = 0; i < mi->n_rates; i++) {
	121	struct minstrel_rate *mr = &mi->r[i];
	122	if (max_tp < mr->cur_tp) {
	123	index_max_tp = i;
	124	max_tp = mr->cur_tp;
	125	}
	126	if (max_prob < mr->probability) {
	127	index_max_prob = i;
	128	max_prob = mr->probability;
	129	}
	130	}
	131
	132	max_tp = 0;
	133	for (i = 0; i < mi->n_rates; i++) {
	134	struct minstrel_rate *mr = &mi->r[i];
	135
	136	if (i == index_max_tp)
	137	continue;
	138
	139	if (max_tp < mr->cur_tp) {
	140	index_max_tp2 = i;
	141	max_tp = mr->cur_tp;
	142	}
	143	}
	144	mi->max_tp_rate = index_max_tp;
	145	mi->max_tp_rate2 = index_max_tp2;
	146	mi->max_prob_rate = index_max_prob;
	147	}
	148
	149	static void
	150	minstrel_tx_status(void priv, struct ieee80211_supported_band sband,
	151	struct ieee80211_sta sta, void priv_sta,
	152	struct sk_buff *skb)
	153	{
8acbcddb	154	struct minstrel_priv *mp = priv;
cccf129f FF	155	struct minstrel_sta_info *mi = priv_sta;
cccf129f FF	156	struct ieee80211_tx_info *info = IEEE80211_SKB_CB(skb);
e6a9854b JB	157	struct ieee80211_tx_rate *ar = info->status.rates;
	158	int i, ndx;
	159	int success;
cccf129f	160
e6a9854b	161	success = !!(info->flags & IEEE80211_TX_STAT_ACK);
cccf129f	162
e6a9854b JB	163	for (i = 0; i < IEEE80211_TX_MAX_RATES; i++) {
e6a9854b JB	164	if (ar[i].idx < 0)
cccf129f FF	165	break;
cccf129f FF	166
e6a9854b	167	ndx = rix_to_ndx(mi, ar[i].idx);
3938b45c LC	168	if (ndx < 0)
	169	continue;
	170
e6a9854b	171	mi->r[ndx].attempts += ar[i].count;
cccf129f	172
bfc32e6a	173	if ((i != IEEE80211_TX_MAX_RATES - 1) && (ar[i + 1].idx < 0))
cccf129f FF	174	mi->r[ndx].success += success;
	175	}
	176
	177	if ((info->flags & IEEE80211_TX_CTL_RATE_CTRL_PROBE) && (i >= 0))
	178	mi->sample_count++;
	179
	180	if (mi->sample_deferred > 0)
	181	mi->sample_deferred--;
8acbcddb JB	182
	183	if (time_after(jiffies, mi->stats_update +
	184	(mp->update_interval * HZ) / 1000))
	185	minstrel_update_stats(mp, mi);
cccf129f FF	186	}
	187
	188
	189	static inline unsigned int
	190	minstrel_get_retry_count(struct minstrel_rate *mr,
	191	struct ieee80211_tx_info *info)
	192	{
	193	unsigned int retry = mr->adjusted_retry_count;
	194
e6a9854b	195	if (info->control.rates[0].flags & IEEE80211_TX_RC_USE_RTS_CTS)
cccf129f	196	retry = max(2U, min(mr->retry_count_rtscts, retry));
e6a9854b	197	else if (info->control.rates[0].flags & IEEE80211_TX_RC_USE_CTS_PROTECT)
cccf129f FF	198	retry = max(2U, min(mr->retry_count_cts, retry));
	199	return retry;
	200	}
	201
	202
	203	static int
	204	minstrel_get_next_sample(struct minstrel_sta_info *mi)
	205	{
	206	unsigned int sample_ndx;
	207	sample_ndx = SAMPLE_TBL(mi, mi->sample_idx, mi->sample_column);
	208	mi->sample_idx++;
5ee58d7e	209	if ((int) mi->sample_idx > (mi->n_rates - 2)) {
cccf129f FF	210	mi->sample_idx = 0;
	211	mi->sample_column++;
	212	if (mi->sample_column >= SAMPLE_COLUMNS)
	213	mi->sample_column = 0;
	214	}
	215	return sample_ndx;
	216	}
	217
2df78167	218	static void
e6a9854b JB	219	minstrel_get_rate(void priv, struct ieee80211_sta sta,
e6a9854b JB	220	void priv_sta, struct ieee80211_tx_rate_control txrc)
cccf129f	221	{
e6a9854b	222	struct sk_buff *skb = txrc->skb;
cccf129f FF	223	struct ieee80211_tx_info *info = IEEE80211_SKB_CB(skb);
	224	struct minstrel_sta_info *mi = priv_sta;
	225	struct minstrel_priv *mp = priv;
e6a9854b	226	struct ieee80211_tx_rate *ar = info->control.rates;
cccf129f FF	227	unsigned int ndx, sample_ndx = 0;
	228	bool mrr;
	229	bool sample_slower = false;
	230	bool sample = false;
	231	int i, delta;
	232	int mrr_ndx[3];
	233	int sample_rate;
	234
4c6d4f5c	235	if (rate_control_send_low(sta, priv_sta, txrc))
cccf129f	236	return;
cccf129f	237
e6a9854b	238	mrr = mp->has_mrr && !txrc->rts && !txrc->bss_conf->use_cts_prot;
cccf129f	239
cccf129f FF	240	ndx = mi->max_tp_rate;
	241
	242	if (mrr)
	243	sample_rate = mp->lookaround_rate_mrr;
	244	else
	245	sample_rate = mp->lookaround_rate;
	246
	247	mi->packet_count++;
	248	delta = (mi->packet_count * sample_rate / 100) -
	249	(mi->sample_count + mi->sample_deferred / 2);
	250
	251	/* delta > 0: sampling required */
f4a8cd94 FF	252	if ((delta > 0) && (mrr \|\| !mi->prev_sample)) {
f4a8cd94 FF	253	struct minstrel_rate *msr;
cccf129f FF	254	if (mi->packet_count >= 10000) {
	255	mi->sample_deferred = 0;
	256	mi->sample_count = 0;
	257	mi->packet_count = 0;
	258	} else if (delta > mi->n_rates * 2) {
	259	/* With multi-rate retry, not every planned sample
	260	* attempt actually gets used, due to the way the retry
	261	* chain is set up - [max_tp,sample,prob,lowest] for
	262	* sample_rate < max_tp.
	263	*
	264	* If there's too much sampling backlog and the link
	265	* starts getting worse, minstrel would start bursting
	266	* out lots of sampling frames, which would result
	267	* in a large throughput loss. */
	268	mi->sample_count += (delta - mi->n_rates * 2);
	269	}
	270
	271	sample_ndx = minstrel_get_next_sample(mi);
f4a8cd94	272	msr = &mi->r[sample_ndx];
cccf129f	273	sample = true;
f4a8cd94	274	sample_slower = mrr && (msr->perfect_tx_time >
cccf129f FF	275	mi->r[ndx].perfect_tx_time);
	276
	277	if (!sample_slower) {
f4a8cd94 FF	278	if (msr->sample_limit != 0) {
	279	ndx = sample_ndx;
	280	mi->sample_count++;
	281	if (msr->sample_limit > 0)
	282	msr->sample_limit--;
	283	} else {
	284	sample = false;
	285	}
cccf129f FF	286	} else {
	287	/* Only use IEEE80211_TX_CTL_RATE_CTRL_PROBE to mark
	288	* packets that have the sampling rate deferred to the
	289	* second MRR stage. Increase the sample counter only
	290	* if the deferred sample rate was actually used.
	291	* Use the sample_deferred counter to make sure that
	292	* the sampling is not done in large bursts */
	293	info->flags \|= IEEE80211_TX_CTL_RATE_CTRL_PROBE;
	294	mi->sample_deferred++;
	295	}
	296	}
f4a8cd94 FF	297	mi->prev_sample = sample;
	298
	299	/* If we're not using MRR and the sampling rate already
	300	* has a probability of >95%, we shouldn't be attempting
	301	* to use it, as this only wastes precious airtime */
c8ca8c2f	302	if (!mrr && sample && (mi->r[ndx].probability > MINSTREL_FRAC(95, 100)))
f4a8cd94 FF	303	ndx = mi->max_tp_rate;
f4a8cd94 FF	304
e6a9854b JB	305	ar[0].idx = mi->r[ndx].rix;
e6a9854b JB	306	ar[0].count = minstrel_get_retry_count(&mi->r[ndx], info);
cccf129f FF	307
cccf129f FF	308	if (!mrr) {
f4a8cd94 FF	309	if (!sample)
f4a8cd94 FF	310	ar[0].count = mp->max_retry;
e6a9854b JB	311	ar[1].idx = mi->lowest_rix;
e6a9854b JB	312	ar[1].count = mp->max_retry;
cccf129f FF	313	return;
	314	}
	315
	316	/* MRR setup */
	317	if (sample) {
	318	if (sample_slower)
	319	mrr_ndx[0] = sample_ndx;
	320	else
	321	mrr_ndx[0] = mi->max_tp_rate;
	322	} else {
	323	mrr_ndx[0] = mi->max_tp_rate2;
	324	}
	325	mrr_ndx[1] = mi->max_prob_rate;
	326	mrr_ndx[2] = 0;
e6a9854b JB	327	for (i = 1; i < 4; i++) {
	328	ar[i].idx = mi->r[mrr_ndx[i - 1]].rix;
	329	ar[i].count = mi->r[mrr_ndx[i - 1]].adjusted_retry_count;
cccf129f FF	330	}
	331	}
	332
	333
	334	static void
4ee73f33 MK	335	calc_rate_durations(enum ieee80211_band band,
4ee73f33 MK	336	struct minstrel_rate *d,
868a5f71	337	struct ieee80211_rate *rate)
cccf129f FF	338	{
	339	int erp = !!(rate->flags & IEEE80211_RATE_ERP_G);
	340
4ee73f33	341	d->perfect_tx_time = ieee80211_frame_duration(band, 1200,
cccf129f	342	rate->bitrate, erp, 1);
4ee73f33	343	d->ack_time = ieee80211_frame_duration(band, 10,
cccf129f FF	344	rate->bitrate, erp, 1);
	345	}
	346
	347	static void
	348	init_sample_table(struct minstrel_sta_info *mi)
	349	{
	350	unsigned int i, col, new_idx;
	351	unsigned int n_srates = mi->n_rates - 1;
	352	u8 rnd[8];
	353
	354	mi->sample_column = 0;
	355	mi->sample_idx = 0;
	356	memset(mi->sample_table, 0, SAMPLE_COLUMNS * mi->n_rates);
	357
	358	for (col = 0; col < SAMPLE_COLUMNS; col++) {
	359	for (i = 0; i < n_srates; i++) {
	360	get_random_bytes(rnd, sizeof(rnd));
	361	new_idx = (i + rnd[i & 7]) % n_srates;
	362
	363	while (SAMPLE_TBL(mi, new_idx, col) != 0)
	364	new_idx = (new_idx + 1) % n_srates;
	365
	366	/* Don't sample the slowest rate (i.e. slowest base
	367	* rate). We must presume that the slowest rate works
	368	* fine, or else other management frames will also be
	369	* failing and the link will break */
	370	SAMPLE_TBL(mi, new_idx, col) = i + 1;
	371	}
	372	}
	373	}
	374
	375	static void
	376	minstrel_rate_init(void priv, struct ieee80211_supported_band sband,
	377	struct ieee80211_sta sta, void priv_sta)
	378	{
	379	struct minstrel_sta_info *mi = priv_sta;
	380	struct minstrel_priv *mp = priv;
d57854bb	381	struct ieee80211_rate *ctl_rate;
cccf129f FF	382	unsigned int i, n = 0;
	383	unsigned int t_slot = 9; /* FIXME: get real slot time */
	384
	385	mi->lowest_rix = rate_lowest_index(sband, sta);
d57854bb	386	ctl_rate = &sband->bitrates[mi->lowest_rix];
4ee73f33 MK	387	mi->sp_ack_dur = ieee80211_frame_duration(sband->band, 10,
4ee73f33 MK	388	ctl_rate->bitrate,
d57854bb	389	!!(ctl_rate->flags & IEEE80211_RATE_ERP_G), 1);
cccf129f FF	390
	391	for (i = 0; i < sband->n_bitrates; i++) {
	392	struct minstrel_rate *mr = &mi->r[n];
	393	unsigned int tx_time = 0, tx_time_cts = 0, tx_time_rtscts = 0;
	394	unsigned int tx_time_single;
	395	unsigned int cw = mp->cw_min;
	396
	397	if (!rate_supported(sta, sband->band, i))
	398	continue;
	399	n++;
	400	memset(mr, 0, sizeof(*mr));
	401
	402	mr->rix = i;
	403	mr->bitrate = sband->bitrates[i].bitrate / 5;
4ee73f33	404	calc_rate_durations(sband->band, mr, &sband->bitrates[i]);
cccf129f FF	405
	406	/* calculate maximum number of retransmissions before
	407	* fallback (based on maximum segment size) */
f4a8cd94	408	mr->sample_limit = -1;
cccf129f FF	409	mr->retry_count = 1;
	410	mr->retry_count_cts = 1;
	411	mr->retry_count_rtscts = 1;
	412	tx_time = mr->perfect_tx_time + mi->sp_ack_dur;
	413	do {
	414	/* add one retransmission */
	415	tx_time_single = mr->ack_time + mr->perfect_tx_time;
	416
	417	/* contention window */
8fddddff DH	418	tx_time_single += (t_slot * cw) >> 1;
8fddddff DH	419	cw = min((cw << 1) \| 1, mp->cw_max);
cccf129f FF	420
	421	tx_time += tx_time_single;
	422	tx_time_cts += tx_time_single + mi->sp_ack_dur;
	423	tx_time_rtscts += tx_time_single + 2 * mi->sp_ack_dur;
	424	if ((tx_time_cts < mp->segment_size) &&
	425	(mr->retry_count_cts < mp->max_retry))
	426	mr->retry_count_cts++;
	427	if ((tx_time_rtscts < mp->segment_size) &&
	428	(mr->retry_count_rtscts < mp->max_retry))
	429	mr->retry_count_rtscts++;
	430	} while ((tx_time < mp->segment_size) &&
	431	(++mr->retry_count < mp->max_retry));
	432	mr->adjusted_retry_count = mr->retry_count;
	433	}
	434
	435	for (i = n; i < sband->n_bitrates; i++) {
	436	struct minstrel_rate *mr = &mi->r[i];
	437	mr->rix = -1;
	438	}
	439
	440	mi->n_rates = n;
	441	mi->stats_update = jiffies;
	442
	443	init_sample_table(mi);
	444	}
	445
	446	static void *
	447	minstrel_alloc_sta(void priv, struct ieee80211_sta sta, gfp_t gfp)
	448	{
	449	struct ieee80211_supported_band *sband;
	450	struct minstrel_sta_info *mi;
	451	struct minstrel_priv *mp = priv;
	452	struct ieee80211_hw *hw = mp->hw;
	453	int max_rates = 0;
	454	int i;
	455
	456	mi = kzalloc(sizeof(struct minstrel_sta_info), gfp);
	457	if (!mi)
	458	return NULL;
	459
	460	for (i = 0; i < IEEE80211_NUM_BANDS; i++) {
8e532175	461	sband = hw->wiphy->bands[i];
621ad7c9	462	if (sband && sband->n_bitrates > max_rates)
cccf129f FF	463	max_rates = sband->n_bitrates;
	464	}
	465
	466	mi->r = kzalloc(sizeof(struct minstrel_rate) * max_rates, gfp);
	467	if (!mi->r)
	468	goto error;
	469
	470	mi->sample_table = kmalloc(SAMPLE_COLUMNS * max_rates, gfp);
	471	if (!mi->sample_table)
	472	goto error1;
	473
	474	mi->stats_update = jiffies;
	475	return mi;
	476
	477	error1:
	478	kfree(mi->r);
	479	error:
	480	kfree(mi);
	481	return NULL;
	482	}
	483
	484	static void
	485	minstrel_free_sta(void priv, struct ieee80211_sta sta, void *priv_sta)
	486	{
	487	struct minstrel_sta_info *mi = priv_sta;
	488
	489	kfree(mi->sample_table);
	490	kfree(mi->r);
	491	kfree(mi);
	492	}
	493
a0497f9f FF	494	static void
	495	minstrel_init_cck_rates(struct minstrel_priv *mp)
	496	{
	497	static const int bitrates[4] = { 10, 20, 55, 110 };
	498	struct ieee80211_supported_band *sband;
	499	int i, j;
	500
	501	sband = mp->hw->wiphy->bands[IEEE80211_BAND_2GHZ];
	502	if (!sband)
	503	return;
	504
	505	for (i = 0, j = 0; i < sband->n_bitrates; i++) {
	506	struct ieee80211_rate *rate = &sband->bitrates[i];
	507
	508	if (rate->flags & IEEE80211_RATE_ERP_G)
	509	continue;
	510
	511	for (j = 0; j < ARRAY_SIZE(bitrates); j++) {
	512	if (rate->bitrate != bitrates[j])
	513	continue;
	514
	515	mp->cck_rates[j] = i;
	516	break;
	517	}
	518	}
	519	}
	520
cccf129f FF	521	static void *
	522	minstrel_alloc(struct ieee80211_hw hw, struct dentry debugfsdir)
	523	{
	524	struct minstrel_priv *mp;
	525
	526	mp = kzalloc(sizeof(struct minstrel_priv), GFP_ATOMIC);
	527	if (!mp)
	528	return NULL;
	529
	530	/* contention window settings
	531	* Just an approximation. Using the per-queue values would complicate
	532	* the calculations and is probably unnecessary */
	533	mp->cw_min = 15;
	534	mp->cw_max = 1023;
	535
	536	/* number of packets (in %) to use for sampling other rates
	537	* sample less often for non-mrr packets, because the overhead
	538	* is much higher than with mrr */
	539	mp->lookaround_rate = 5;
	540	mp->lookaround_rate_mrr = 10;
	541
cccf129f FF	542	/* maximum time that the hw is allowed to stay in one MRR segment */
	543	mp->segment_size = 6000;
	544
e6a9854b JB	545	if (hw->max_rate_tries > 0)
e6a9854b JB	546	mp->max_retry = hw->max_rate_tries;
cccf129f FF	547	else
	548	/* safe default, does not necessarily have to match hw properties */
	549	mp->max_retry = 7;
	550
e6a9854b	551	if (hw->max_rates >= 4)
cccf129f FF	552	mp->has_mrr = true;
	553
	554	mp->hw = hw;
	555	mp->update_interval = 100;
	556
24f7580e ZK	557	#ifdef CONFIG_MAC80211_DEBUGFS
	558	mp->fixed_rate_idx = (u32) -1;
	559	mp->dbg_fixed_rate = debugfs_create_u32("fixed_rate_idx",
	560	S_IRUGO \| S_IWUGO, debugfsdir, &mp->fixed_rate_idx);
	561	#endif
	562
a0497f9f FF	563	minstrel_init_cck_rates(mp);
a0497f9f FF	564
cccf129f FF	565	return mp;
	566	}
	567
	568	static void
	569	minstrel_free(void *priv)
	570	{
24f7580e ZK	571	#ifdef CONFIG_MAC80211_DEBUGFS
	572	debugfs_remove(((struct minstrel_priv *)priv)->dbg_fixed_rate);
	573	#endif
cccf129f FF	574	kfree(priv);
	575	}
	576
eae44756	577	struct rate_control_ops mac80211_minstrel = {
cccf129f FF	578	.name = "minstrel",
	579	.tx_status = minstrel_tx_status,
	580	.get_rate = minstrel_get_rate,
	581	.rate_init = minstrel_rate_init,
cccf129f FF	582	.alloc = minstrel_alloc,
	583	.free = minstrel_free,
	584	.alloc_sta = minstrel_alloc_sta,
	585	.free_sta = minstrel_free_sta,
	586	#ifdef CONFIG_MAC80211_DEBUGFS
	587	.add_sta_debugfs = minstrel_add_sta_debugfs,
	588	.remove_sta_debugfs = minstrel_remove_sta_debugfs,
	589	#endif
	590	};
	591
	592	int __init
	593	rc80211_minstrel_init(void)
	594	{
	595	return ieee80211_rate_control_register(&mac80211_minstrel);
	596	}
	597
	598	void
	599	rc80211_minstrel_exit(void)
	600	{
	601	ieee80211_rate_control_unregister(&mac80211_minstrel);
	602	}
	603