[GitHub/mt8127/android_kernel_alcatel_ttab.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;
	WARN_ON(i < 0);
	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;
	u32 p;
	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;

		/* To avoid rounding issues, probabilities scale from 0 (0%)
		 * to 18000 (100%) */
		if (mr->attempts) {
			p = (mr->success * 18000) / mr->attempts;
			mr->succ_hist += mr->success;
			mr->att_hist += mr->attempts;
			mr->cur_prob = p;
			p = ((p * (100 - mp->ewma_level)) + (mr->probability *
				mp->ewma_level)) / 100;
			mr->probability = p;
			mr->cur_tp = p * (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 > 17100) || (mr->probability < 1800)) {
			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_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--;
}


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;

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

	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 > 17100))
		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(struct minstrel_sta_info *mi, struct ieee80211_local *local,
                    struct minstrel_rate *d, struct ieee80211_rate *rate)
{
	int erp = !!(rate->flags & IEEE80211_RATE_ERP_G);

	d->perfect_tx_time = ieee80211_frame_duration(local, 1200,
			rate->bitrate, erp, 1);
	d->ack_time = ieee80211_frame_duration(local, 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_local *local = hw_to_local(mp->hw);
	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(local, 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(mi, local, 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 + min(cw, mp->cw_max);
			cw = (cw << 1) | 1;

			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_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;

	/* moving average weight for EWMA */
	mp->ewma_level = 75;

	/* 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;

	return mp;
}

static void
minstrel_free(void *priv)
{
	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;
3938b45c	70	WARN_ON(i < 0);
cccf129f FF	71	return i;
	72	}
	73
cccf129f FF	74	static void
	75	minstrel_update_stats(struct minstrel_priv mp, struct minstrel_sta_info mi)
	76	{
	77	u32 max_tp = 0, index_max_tp = 0, index_max_tp2 = 0;
	78	u32 max_prob = 0, index_max_prob = 0;
	79	u32 usecs;
	80	u32 p;
	81	int i;
	82
	83	mi->stats_update = jiffies;
	84	for (i = 0; i < mi->n_rates; i++) {
	85	struct minstrel_rate *mr = &mi->r[i];
	86
	87	usecs = mr->perfect_tx_time;
	88	if (!usecs)
	89	usecs = 1000000;
	90
	91	/* To avoid rounding issues, probabilities scale from 0 (0%)
	92	* to 18000 (100%) */
	93	if (mr->attempts) {
	94	p = (mr->success * 18000) / mr->attempts;
	95	mr->succ_hist += mr->success;
	96	mr->att_hist += mr->attempts;
	97	mr->cur_prob = p;
	98	p = ((p * (100 - mp->ewma_level)) + (mr->probability *
	99	mp->ewma_level)) / 100;
	100	mr->probability = p;
	101	mr->cur_tp = p * (1000000 / usecs);
	102	}
	103
	104	mr->last_success = mr->success;
	105	mr->last_attempts = mr->attempts;
	106	mr->success = 0;
	107	mr->attempts = 0;
	108
	109	/* Sample less often below the 10% chance of success.
	110	* Sample less often above the 95% chance of success. */
	111	if ((mr->probability > 17100) \|\| (mr->probability < 1800)) {
	112	mr->adjusted_retry_count = mr->retry_count >> 1;
	113	if (mr->adjusted_retry_count > 2)
	114	mr->adjusted_retry_count = 2;
f4a8cd94	115	mr->sample_limit = 4;
cccf129f	116	} else {
f4a8cd94	117	mr->sample_limit = -1;
cccf129f FF	118	mr->adjusted_retry_count = mr->retry_count;
	119	}
	120	if (!mr->adjusted_retry_count)
	121	mr->adjusted_retry_count = 2;
	122	}
	123
	124	for (i = 0; i < mi->n_rates; i++) {
	125	struct minstrel_rate *mr = &mi->r[i];
	126	if (max_tp < mr->cur_tp) {
	127	index_max_tp = i;
	128	max_tp = mr->cur_tp;
	129	}
	130	if (max_prob < mr->probability) {
	131	index_max_prob = i;
	132	max_prob = mr->probability;
	133	}
	134	}
	135
	136	max_tp = 0;
	137	for (i = 0; i < mi->n_rates; i++) {
	138	struct minstrel_rate *mr = &mi->r[i];
	139
	140	if (i == index_max_tp)
	141	continue;
	142
	143	if (max_tp < mr->cur_tp) {
	144	index_max_tp2 = i;
	145	max_tp = mr->cur_tp;
	146	}
	147	}
	148	mi->max_tp_rate = index_max_tp;
	149	mi->max_tp_rate2 = index_max_tp2;
	150	mi->max_prob_rate = index_max_prob;
	151	}
	152
	153	static void
	154	minstrel_tx_status(void priv, struct ieee80211_supported_band sband,
	155	struct ieee80211_sta sta, void priv_sta,
	156	struct sk_buff *skb)
	157	{
	158	struct minstrel_sta_info *mi = priv_sta;
	159	struct ieee80211_tx_info *info = IEEE80211_SKB_CB(skb);
e6a9854b JB	160	struct ieee80211_tx_rate *ar = info->status.rates;
	161	int i, ndx;
	162	int success;
cccf129f	163
e6a9854b	164	success = !!(info->flags & IEEE80211_TX_STAT_ACK);
cccf129f	165
e6a9854b JB	166	for (i = 0; i < IEEE80211_TX_MAX_RATES; i++) {
e6a9854b JB	167	if (ar[i].idx < 0)
cccf129f FF	168	break;
cccf129f FF	169
e6a9854b	170	ndx = rix_to_ndx(mi, ar[i].idx);
3938b45c LC	171	if (ndx < 0)
	172	continue;
	173
e6a9854b	174	mi->r[ndx].attempts += ar[i].count;
cccf129f	175
bfc32e6a	176	if ((i != IEEE80211_TX_MAX_RATES - 1) && (ar[i + 1].idx < 0))
cccf129f FF	177	mi->r[ndx].success += success;
	178	}
	179
	180	if ((info->flags & IEEE80211_TX_CTL_RATE_CTRL_PROBE) && (i >= 0))
	181	mi->sample_count++;
	182
	183	if (mi->sample_deferred > 0)
	184	mi->sample_deferred--;
	185	}
	186
	187
	188	static inline unsigned int
	189	minstrel_get_retry_count(struct minstrel_rate *mr,
	190	struct ieee80211_tx_info *info)
	191	{
	192	unsigned int retry = mr->adjusted_retry_count;
	193
e6a9854b	194	if (info->control.rates[0].flags & IEEE80211_TX_RC_USE_RTS_CTS)
cccf129f	195	retry = max(2U, min(mr->retry_count_rtscts, retry));
e6a9854b	196	else if (info->control.rates[0].flags & IEEE80211_TX_RC_USE_CTS_PROTECT)
cccf129f FF	197	retry = max(2U, min(mr->retry_count_cts, retry));
	198	return retry;
	199	}
	200
	201
	202	static int
	203	minstrel_get_next_sample(struct minstrel_sta_info *mi)
	204	{
	205	unsigned int sample_ndx;
	206	sample_ndx = SAMPLE_TBL(mi, mi->sample_idx, mi->sample_column);
	207	mi->sample_idx++;
5ee58d7e	208	if ((int) mi->sample_idx > (mi->n_rates - 2)) {
cccf129f FF	209	mi->sample_idx = 0;
	210	mi->sample_column++;
	211	if (mi->sample_column >= SAMPLE_COLUMNS)
	212	mi->sample_column = 0;
	213	}
	214	return sample_ndx;
	215	}
	216
2df78167	217	static void
e6a9854b JB	218	minstrel_get_rate(void priv, struct ieee80211_sta sta,
e6a9854b JB	219	void priv_sta, struct ieee80211_tx_rate_control txrc)
cccf129f	220	{
e6a9854b	221	struct sk_buff *skb = txrc->skb;
cccf129f FF	222	struct ieee80211_tx_info *info = IEEE80211_SKB_CB(skb);
	223	struct minstrel_sta_info *mi = priv_sta;
	224	struct minstrel_priv *mp = priv;
e6a9854b	225	struct ieee80211_tx_rate *ar = info->control.rates;
cccf129f FF	226	unsigned int ndx, sample_ndx = 0;
	227	bool mrr;
	228	bool sample_slower = false;
	229	bool sample = false;
	230	int i, delta;
	231	int mrr_ndx[3];
	232	int sample_rate;
	233
4c6d4f5c	234	if (rate_control_send_low(sta, priv_sta, txrc))
cccf129f	235	return;
cccf129f	236
e6a9854b	237	mrr = mp->has_mrr && !txrc->rts && !txrc->bss_conf->use_cts_prot;
cccf129f FF	238
	239	if (time_after(jiffies, mi->stats_update + (mp->update_interval *
	240	HZ) / 1000))
	241	minstrel_update_stats(mp, mi);
	242
	243	ndx = mi->max_tp_rate;
	244
	245	if (mrr)
	246	sample_rate = mp->lookaround_rate_mrr;
	247	else
	248	sample_rate = mp->lookaround_rate;
	249
	250	mi->packet_count++;
	251	delta = (mi->packet_count * sample_rate / 100) -
	252	(mi->sample_count + mi->sample_deferred / 2);
	253
	254	/* delta > 0: sampling required */
f4a8cd94 FF	255	if ((delta > 0) && (mrr \|\| !mi->prev_sample)) {
f4a8cd94 FF	256	struct minstrel_rate *msr;
cccf129f FF	257	if (mi->packet_count >= 10000) {
	258	mi->sample_deferred = 0;
	259	mi->sample_count = 0;
	260	mi->packet_count = 0;
	261	} else if (delta > mi->n_rates * 2) {
	262	/* With multi-rate retry, not every planned sample
	263	* attempt actually gets used, due to the way the retry
	264	* chain is set up - [max_tp,sample,prob,lowest] for
	265	* sample_rate < max_tp.
	266	*
	267	* If there's too much sampling backlog and the link
	268	* starts getting worse, minstrel would start bursting
	269	* out lots of sampling frames, which would result
	270	* in a large throughput loss. */
	271	mi->sample_count += (delta - mi->n_rates * 2);
	272	}
	273
	274	sample_ndx = minstrel_get_next_sample(mi);
f4a8cd94	275	msr = &mi->r[sample_ndx];
cccf129f	276	sample = true;
f4a8cd94	277	sample_slower = mrr && (msr->perfect_tx_time >
cccf129f FF	278	mi->r[ndx].perfect_tx_time);
	279
	280	if (!sample_slower) {
f4a8cd94 FF	281	if (msr->sample_limit != 0) {
	282	ndx = sample_ndx;
	283	mi->sample_count++;
	284	if (msr->sample_limit > 0)
	285	msr->sample_limit--;
	286	} else {
	287	sample = false;
	288	}
cccf129f FF	289	} else {
	290	/* Only use IEEE80211_TX_CTL_RATE_CTRL_PROBE to mark
	291	* packets that have the sampling rate deferred to the
	292	* second MRR stage. Increase the sample counter only
	293	* if the deferred sample rate was actually used.
	294	* Use the sample_deferred counter to make sure that
	295	* the sampling is not done in large bursts */
	296	info->flags \|= IEEE80211_TX_CTL_RATE_CTRL_PROBE;
	297	mi->sample_deferred++;
	298	}
	299	}
f4a8cd94 FF	300	mi->prev_sample = sample;
	301
	302	/* If we're not using MRR and the sampling rate already
	303	* has a probability of >95%, we shouldn't be attempting
	304	* to use it, as this only wastes precious airtime */
	305	if (!mrr && sample && (mi->r[ndx].probability > 17100))
	306	ndx = mi->max_tp_rate;
	307
e6a9854b JB	308	ar[0].idx = mi->r[ndx].rix;
e6a9854b JB	309	ar[0].count = minstrel_get_retry_count(&mi->r[ndx], info);
cccf129f FF	310
cccf129f FF	311	if (!mrr) {
f4a8cd94 FF	312	if (!sample)
f4a8cd94 FF	313	ar[0].count = mp->max_retry;
e6a9854b JB	314	ar[1].idx = mi->lowest_rix;
e6a9854b JB	315	ar[1].count = mp->max_retry;
cccf129f FF	316	return;
	317	}
	318
	319	/* MRR setup */
	320	if (sample) {
	321	if (sample_slower)
	322	mrr_ndx[0] = sample_ndx;
	323	else
	324	mrr_ndx[0] = mi->max_tp_rate;
	325	} else {
	326	mrr_ndx[0] = mi->max_tp_rate2;
	327	}
	328	mrr_ndx[1] = mi->max_prob_rate;
	329	mrr_ndx[2] = 0;
e6a9854b JB	330	for (i = 1; i < 4; i++) {
	331	ar[i].idx = mi->r[mrr_ndx[i - 1]].rix;
	332	ar[i].count = mi->r[mrr_ndx[i - 1]].adjusted_retry_count;
cccf129f FF	333	}
	334	}
	335
	336
	337	static void
	338	calc_rate_durations(struct minstrel_sta_info mi, struct ieee80211_local local,
	339	struct minstrel_rate d, struct ieee80211_rate rate)
	340	{
	341	int erp = !!(rate->flags & IEEE80211_RATE_ERP_G);
	342
	343	d->perfect_tx_time = ieee80211_frame_duration(local, 1200,
	344	rate->bitrate, erp, 1);
	345	d->ack_time = ieee80211_frame_duration(local, 10,
	346	rate->bitrate, erp, 1);
	347	}
	348
	349	static void
	350	init_sample_table(struct minstrel_sta_info *mi)
	351	{
	352	unsigned int i, col, new_idx;
	353	unsigned int n_srates = mi->n_rates - 1;
	354	u8 rnd[8];
	355
	356	mi->sample_column = 0;
	357	mi->sample_idx = 0;
	358	memset(mi->sample_table, 0, SAMPLE_COLUMNS * mi->n_rates);
	359
	360	for (col = 0; col < SAMPLE_COLUMNS; col++) {
	361	for (i = 0; i < n_srates; i++) {
	362	get_random_bytes(rnd, sizeof(rnd));
	363	new_idx = (i + rnd[i & 7]) % n_srates;
	364
	365	while (SAMPLE_TBL(mi, new_idx, col) != 0)
	366	new_idx = (new_idx + 1) % n_srates;
	367
	368	/* Don't sample the slowest rate (i.e. slowest base
	369	* rate). We must presume that the slowest rate works
	370	* fine, or else other management frames will also be
	371	* failing and the link will break */
	372	SAMPLE_TBL(mi, new_idx, col) = i + 1;
	373	}
	374	}
	375	}
	376
	377	static void
	378	minstrel_rate_init(void priv, struct ieee80211_supported_band sband,
	379	struct ieee80211_sta sta, void priv_sta)
	380	{
	381	struct minstrel_sta_info *mi = priv_sta;
	382	struct minstrel_priv *mp = priv;
d57854bb CL	383	struct ieee80211_local *local = hw_to_local(mp->hw);
d57854bb CL	384	struct ieee80211_rate *ctl_rate;
cccf129f FF	385	unsigned int i, n = 0;
	386	unsigned int t_slot = 9; /* FIXME: get real slot time */
	387
	388	mi->lowest_rix = rate_lowest_index(sband, sta);
d57854bb CL	389	ctl_rate = &sband->bitrates[mi->lowest_rix];
	390	mi->sp_ack_dur = ieee80211_frame_duration(local, 10, ctl_rate->bitrate,
	391	!!(ctl_rate->flags & IEEE80211_RATE_ERP_G), 1);
cccf129f FF	392
	393	for (i = 0; i < sband->n_bitrates; i++) {
	394	struct minstrel_rate *mr = &mi->r[n];
	395	unsigned int tx_time = 0, tx_time_cts = 0, tx_time_rtscts = 0;
	396	unsigned int tx_time_single;
	397	unsigned int cw = mp->cw_min;
	398
	399	if (!rate_supported(sta, sband->band, i))
	400	continue;
	401	n++;
	402	memset(mr, 0, sizeof(*mr));
	403
	404	mr->rix = i;
	405	mr->bitrate = sband->bitrates[i].bitrate / 5;
d57854bb	406	calc_rate_durations(mi, local, mr,
cccf129f FF	407	&sband->bitrates[i]);
	408
	409	/* calculate maximum number of retransmissions before
	410	* fallback (based on maximum segment size) */
f4a8cd94	411	mr->sample_limit = -1;
cccf129f FF	412	mr->retry_count = 1;
	413	mr->retry_count_cts = 1;
	414	mr->retry_count_rtscts = 1;
	415	tx_time = mr->perfect_tx_time + mi->sp_ack_dur;
	416	do {
	417	/* add one retransmission */
	418	tx_time_single = mr->ack_time + mr->perfect_tx_time;
	419
	420	/* contention window */
	421	tx_time_single += t_slot + min(cw, mp->cw_max);
8c6c03fe	422	cw = (cw << 1) \| 1;
cccf129f FF	423
	424	tx_time += tx_time_single;
	425	tx_time_cts += tx_time_single + mi->sp_ack_dur;
	426	tx_time_rtscts += tx_time_single + 2 * mi->sp_ack_dur;
	427	if ((tx_time_cts < mp->segment_size) &&
	428	(mr->retry_count_cts < mp->max_retry))
	429	mr->retry_count_cts++;
	430	if ((tx_time_rtscts < mp->segment_size) &&
	431	(mr->retry_count_rtscts < mp->max_retry))
	432	mr->retry_count_rtscts++;
	433	} while ((tx_time < mp->segment_size) &&
	434	(++mr->retry_count < mp->max_retry));
	435	mr->adjusted_retry_count = mr->retry_count;
	436	}
	437
	438	for (i = n; i < sband->n_bitrates; i++) {
	439	struct minstrel_rate *mr = &mi->r[i];
	440	mr->rix = -1;
	441	}
	442
	443	mi->n_rates = n;
	444	mi->stats_update = jiffies;
	445
	446	init_sample_table(mi);
	447	}
	448
	449	static void *
	450	minstrel_alloc_sta(void priv, struct ieee80211_sta sta, gfp_t gfp)
	451	{
	452	struct ieee80211_supported_band *sband;
	453	struct minstrel_sta_info *mi;
	454	struct minstrel_priv *mp = priv;
	455	struct ieee80211_hw *hw = mp->hw;
	456	int max_rates = 0;
	457	int i;
	458
	459	mi = kzalloc(sizeof(struct minstrel_sta_info), gfp);
	460	if (!mi)
	461	return NULL;
	462
	463	for (i = 0; i < IEEE80211_NUM_BANDS; i++) {
8e532175	464	sband = hw->wiphy->bands[i];
621ad7c9	465	if (sband && sband->n_bitrates > max_rates)
cccf129f FF	466	max_rates = sband->n_bitrates;
	467	}
	468
	469	mi->r = kzalloc(sizeof(struct minstrel_rate) * max_rates, gfp);
	470	if (!mi->r)
	471	goto error;
	472
	473	mi->sample_table = kmalloc(SAMPLE_COLUMNS * max_rates, gfp);
	474	if (!mi->sample_table)
	475	goto error1;
	476
	477	mi->stats_update = jiffies;
	478	return mi;
	479
	480	error1:
	481	kfree(mi->r);
	482	error:
	483	kfree(mi);
	484	return NULL;
	485	}
	486
	487	static void
	488	minstrel_free_sta(void priv, struct ieee80211_sta sta, void *priv_sta)
	489	{
	490	struct minstrel_sta_info *mi = priv_sta;
	491
	492	kfree(mi->sample_table);
	493	kfree(mi->r);
	494	kfree(mi);
	495	}
	496
cccf129f FF	497	static void *
	498	minstrel_alloc(struct ieee80211_hw hw, struct dentry debugfsdir)
	499	{
	500	struct minstrel_priv *mp;
	501
	502	mp = kzalloc(sizeof(struct minstrel_priv), GFP_ATOMIC);
	503	if (!mp)
	504	return NULL;
	505
	506	/* contention window settings
	507	* Just an approximation. Using the per-queue values would complicate
	508	* the calculations and is probably unnecessary */
	509	mp->cw_min = 15;
	510	mp->cw_max = 1023;
	511
	512	/* number of packets (in %) to use for sampling other rates
	513	* sample less often for non-mrr packets, because the overhead
	514	* is much higher than with mrr */
	515	mp->lookaround_rate = 5;
	516	mp->lookaround_rate_mrr = 10;
	517
	518	/* moving average weight for EWMA */
	519	mp->ewma_level = 75;
	520
	521	/* maximum time that the hw is allowed to stay in one MRR segment */
	522	mp->segment_size = 6000;
	523
e6a9854b JB	524	if (hw->max_rate_tries > 0)
e6a9854b JB	525	mp->max_retry = hw->max_rate_tries;
cccf129f FF	526	else
	527	/* safe default, does not necessarily have to match hw properties */
	528	mp->max_retry = 7;
	529
e6a9854b	530	if (hw->max_rates >= 4)
cccf129f FF	531	mp->has_mrr = true;
	532
	533	mp->hw = hw;
	534	mp->update_interval = 100;
	535
	536	return mp;
	537	}
	538
	539	static void
	540	minstrel_free(void *priv)
	541	{
	542	kfree(priv);
	543	}
	544
eae44756	545	struct rate_control_ops mac80211_minstrel = {
cccf129f FF	546	.name = "minstrel",
	547	.tx_status = minstrel_tx_status,
	548	.get_rate = minstrel_get_rate,
	549	.rate_init = minstrel_rate_init,
cccf129f FF	550	.alloc = minstrel_alloc,
	551	.free = minstrel_free,
	552	.alloc_sta = minstrel_alloc_sta,
	553	.free_sta = minstrel_free_sta,
	554	#ifdef CONFIG_MAC80211_DEBUGFS
	555	.add_sta_debugfs = minstrel_add_sta_debugfs,
	556	.remove_sta_debugfs = minstrel_remove_sta_debugfs,
	557	#endif
	558	};
	559
	560	int __init
	561	rc80211_minstrel_init(void)
	562	{
	563	return ieee80211_rate_control_register(&mac80211_minstrel);
	564	}
	565
	566	void
	567	rc80211_minstrel_exit(void)
	568	{
	569	ieee80211_rate_control_unregister(&mac80211_minstrel);
	570	}
	571