/*

   * Copyright (C) 2010-2013 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.
   */
  #include <linux/netdevice.h>
  #include <linux/types.h>
  #include <linux/skbuff.h>
  #include <linux/debugfs.h>
  #include <linux/random.h>

  #include <linux/moduleparam.h>

  #include <linux/ieee80211.h>
  #include <net/mac80211.h>
  #include "rate.h"

  #include "sta_info.h"

  #include "rc80211_minstrel.h"
  #include "rc80211_minstrel_ht.h"

  #define AVG_AMPDU_SIZE	16

  #define AVG_PKT_SIZE	1200

  
  /* Number of bits for an average sized packet */

  #define MCS_NBITS ((AVG_PKT_SIZE * AVG_AMPDU_SIZE) << 3)

  
  /* Number of symbols for a packet with (bps) bits per symbol */

  #define MCS_NSYMS(bps) DIV_ROUND_UP(MCS_NBITS, (bps))

  /* Transmission time (nanoseconds) for a packet containing (syms) symbols */

  #define MCS_SYMBOL_TIME(sgi, syms)					\
  	(sgi ?								\

  	  ((syms) * 18000 + 4000) / 5 :	/* syms * 3.6 us */		\
  	  ((syms) * 1000) << 2		/* syms * 4 us */		\

  	)
  
  /* 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))) / AVG_AMPDU_SIZE)

  #define BW_20			0
  #define BW_40			1

  #define BW_80			2

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

  	MINSTREL_HT_GROUP_0 +			\

  	MINSTREL_MAX_STREAMS * 2 * _ht40 +	\

  	MINSTREL_MAX_STREAMS * _sgi +	\

  	_streams - 1

  /* MCS rate information for an MCS group */

  #define MCS_GROUP(_streams, _sgi, _ht40)				\
  	[GROUP_IDX(_streams, _sgi, _ht40)] = {				\

  	.streams = _streams,						\
  	.flags =							\

  		IEEE80211_TX_RC_MCS |					\

  		(_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)		\
  	}								\
  }

  #define VHT_GROUP_IDX(_streams, _sgi, _bw)				\
  	(MINSTREL_VHT_GROUP_0 +						\
  	 MINSTREL_MAX_STREAMS * 2 * (_bw) +				\
  	 MINSTREL_MAX_STREAMS * (_sgi) +				\
  	 (_streams) - 1)
  
  #define BW2VBPS(_bw, r3, r2, r1)					\
  	(_bw == BW_80 ? r3 : _bw == BW_40 ? r2 : r1)
  
  #define VHT_GROUP(_streams, _sgi, _bw)					\
  	[VHT_GROUP_IDX(_streams, _sgi, _bw)] = {			\
  	.streams = _streams,						\
  	.flags =							\
  		IEEE80211_TX_RC_VHT_MCS |				\
  		(_sgi ? IEEE80211_TX_RC_SHORT_GI : 0) |			\
  		(_bw == BW_80 ? IEEE80211_TX_RC_80_MHZ_WIDTH :		\
  		 _bw == BW_40 ? IEEE80211_TX_RC_40_MHZ_WIDTH : 0),	\
  	.duration = {							\
  		MCS_DURATION(_streams, _sgi,				\
  			     BW2VBPS(_bw,  117,  54,  26)),		\
  		MCS_DURATION(_streams, _sgi,				\
  			     BW2VBPS(_bw,  234, 108,  52)),		\
  		MCS_DURATION(_streams, _sgi,				\
  			     BW2VBPS(_bw,  351, 162,  78)),		\
  		MCS_DURATION(_streams, _sgi,				\
  			     BW2VBPS(_bw,  468, 216, 104)),		\
  		MCS_DURATION(_streams, _sgi,				\
  			     BW2VBPS(_bw,  702, 324, 156)),		\
  		MCS_DURATION(_streams, _sgi,				\
  			     BW2VBPS(_bw,  936, 432, 208)),		\
  		MCS_DURATION(_streams, _sgi,				\
  			     BW2VBPS(_bw, 1053, 486, 234)),		\
  		MCS_DURATION(_streams, _sgi,				\
  			     BW2VBPS(_bw, 1170, 540, 260)),		\
  		MCS_DURATION(_streams, _sgi,				\
  			     BW2VBPS(_bw, 1404, 648, 312)),		\
  		MCS_DURATION(_streams, _sgi,				\
  			     BW2VBPS(_bw, 1560, 720, 346))		\
  	}								\
  }

  #define CCK_DURATION(_bitrate, _short, _len)		\

  	(1000 * (10 /* SIFS */ +			\

  	 (_short ? 72 + 24 : 144 + 48) +		\

  	 (8 * (_len + 4) * 10) / (_bitrate)))

  
  #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_CCK_GROUP] = {			\
  		.streams = 0,				\

  		.flags = 0,				\

  		.duration = {				\
  			CCK_DURATION_LIST(false),	\
  			CCK_DURATION_LIST(true)		\
  		}					\

  	}

  #ifdef CONFIG_MAC80211_RC_MINSTREL_VHT
  static bool minstrel_vht_only = true;
  module_param(minstrel_vht_only, bool, 0644);
  MODULE_PARM_DESC(minstrel_vht_only,
  		 "Use only VHT rates when VHT is supported by sta.");
  #endif

  /*
   * 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.

   *
   * Sortorder has to be fixed for GROUP_IDX macro to be applicable:

   * BW -> SGI -> #streams

   */
  const struct mcs_group minstrel_mcs_groups[] = {

  	MCS_GROUP(1, 0, BW_20),
  	MCS_GROUP(2, 0, BW_20),

  	MCS_GROUP(3, 0, BW_20),

  	MCS_GROUP(1, 1, BW_20),
  	MCS_GROUP(2, 1, BW_20),

  	MCS_GROUP(3, 1, BW_20),

  	MCS_GROUP(1, 0, BW_40),
  	MCS_GROUP(2, 0, BW_40),

  	MCS_GROUP(3, 0, BW_40),

  	MCS_GROUP(1, 1, BW_40),
  	MCS_GROUP(2, 1, BW_40),

  	MCS_GROUP(3, 1, BW_40),

  	CCK_GROUP,
  
  #ifdef CONFIG_MAC80211_RC_MINSTREL_VHT
  	VHT_GROUP(1, 0, BW_20),
  	VHT_GROUP(2, 0, BW_20),

  	VHT_GROUP(3, 0, BW_20),

  
  	VHT_GROUP(1, 1, BW_20),
  	VHT_GROUP(2, 1, BW_20),

  	VHT_GROUP(3, 1, BW_20),

  	VHT_GROUP(1, 0, BW_40),
  	VHT_GROUP(2, 0, BW_40),

  	VHT_GROUP(3, 0, BW_40),

  
  	VHT_GROUP(1, 1, BW_40),
  	VHT_GROUP(2, 1, BW_40),

  	VHT_GROUP(3, 1, BW_40),

  
  	VHT_GROUP(1, 0, BW_80),
  	VHT_GROUP(2, 0, BW_80),

  	VHT_GROUP(3, 0, BW_80),

  
  	VHT_GROUP(1, 1, BW_80),
  	VHT_GROUP(2, 1, BW_80),

  	VHT_GROUP(3, 1, BW_80),
  #endif

  };

  static u8 sample_table[SAMPLE_COLUMNS][MCS_GROUP_RATES] __read_mostly;

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

  /*

   * Some VHT MCSes are invalid (when Ndbps / Nes is not an integer)
   * e.g for MCS9@20MHzx1Nss: Ndbps=8x52*(5/6) Nes=1
   *
   * Returns the valid mcs map for struct minstrel_mcs_group_data.supported
   */
  static u16
  minstrel_get_valid_vht_rates(int bw, int nss, __le16 mcs_map)
  {
  	u16 mask = 0;
  
  	if (bw == BW_20) {
  		if (nss != 3 && nss != 6)
  			mask = BIT(9);
  	} else if (bw == BW_80) {
  		if (nss == 3 || nss == 7)
  			mask = BIT(6);
  		else if (nss == 6)
  			mask = BIT(9);
  	} else {
  		WARN_ON(bw != BW_40);
  	}
  
  	switch ((le16_to_cpu(mcs_map) >> (2 * (nss - 1))) & 3) {
  	case IEEE80211_VHT_MCS_SUPPORT_0_7:
  		mask |= 0x300;
  		break;
  	case IEEE80211_VHT_MCS_SUPPORT_0_8:
  		mask |= 0x200;
  		break;
  	case IEEE80211_VHT_MCS_SUPPORT_0_9:
  		break;
  	default:
  		mask = 0x3ff;
  	}
  
  	return 0x3ff & ~mask;
  }
  
  /*

   * Look up an MCS group index based on mac80211 rate information
   */
  static int
  minstrel_ht_get_group_idx(struct ieee80211_tx_rate *rate)
  {

  	return GROUP_IDX((rate->idx / 8) + 1,

  			 !!(rate->flags & IEEE80211_TX_RC_SHORT_GI),
  			 !!(rate->flags & IEEE80211_TX_RC_40_MHZ_WIDTH));

  }

  static int
  minstrel_vht_get_group_idx(struct ieee80211_tx_rate *rate)
  {
  	return VHT_GROUP_IDX(ieee80211_rate_get_vht_nss(rate),
  			     !!(rate->flags & IEEE80211_TX_RC_SHORT_GI),
  			     !!(rate->flags & IEEE80211_TX_RC_40_MHZ_WIDTH) +
  			     2*!!(rate->flags & IEEE80211_TX_RC_80_MHZ_WIDTH));
  }

  static struct minstrel_rate_stats *
  minstrel_ht_get_stats(struct minstrel_priv *mp, struct minstrel_ht_sta *mi,
  		      struct ieee80211_tx_rate *rate)
  {
  	int group, idx;
  
  	if (rate->flags & IEEE80211_TX_RC_MCS) {
  		group = minstrel_ht_get_group_idx(rate);

  		idx = rate->idx % 8;

  	} else if (rate->flags & IEEE80211_TX_RC_VHT_MCS) {
  		group = minstrel_vht_get_group_idx(rate);
  		idx = ieee80211_rate_get_vht_mcs(rate);

  	} 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->supported[group] & BIT(idx)))

  			idx += 4;
  	}
  	return &mi->groups[group].rates[idx];
  }

  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];
  }

  /*

   * Return current throughput based on the average A-MPDU length, taking into
   * account the expected number of retransmissions and their expected length

   */

  int

  minstrel_ht_get_tp_avg(struct minstrel_ht_sta *mi, int group, int rate,
  		       int prob_ewma)

  {

  	unsigned int nsecs = 0;

  	/* do not account throughput if sucess prob is below 10% */

  	if (prob_ewma < MINSTREL_FRAC(10, 100))

  		return 0;

  	if (group != MINSTREL_CCK_GROUP)

  		nsecs = 1000 * mi->overhead / MINSTREL_TRUNC(mi->avg_ampdu_len);

  	nsecs += minstrel_mcs_groups[group].duration[rate];

  	/*
  	 * For the throughput calculation, limit the probability value to 90% to
  	 * account for collision related packet error rate fluctuation
  	 * (prob is scaled - see MINSTREL_FRAC above)
  	 */
  	if (prob_ewma > MINSTREL_FRAC(90, 100))
  		return MINSTREL_TRUNC(100000 * ((MINSTREL_FRAC(90, 100) * 1000)
  								      / nsecs));
  	else
  		return MINSTREL_TRUNC(100000 * ((prob_ewma * 1000) / nsecs));

  }
  
  /*

   * Find & sort topmost throughput rates
   *
   * If multiple rates provide equal throughput the sorting is based on their
   * current success probability. Higher success probability is preferred among
   * MCS groups, CCK rates do not provide aggregation and are therefore at last.
   */
  static void

  minstrel_ht_sort_best_tp_rates(struct minstrel_ht_sta *mi, u16 index,
  			       u16 *tp_list)

  {

  	int cur_group, cur_idx, cur_tp_avg, cur_prob;
  	int tmp_group, tmp_idx, tmp_tp_avg, tmp_prob;

  	int j = MAX_THR_RATES;
  
  	cur_group = index / MCS_GROUP_RATES;
  	cur_idx = index  % MCS_GROUP_RATES;

  	cur_prob = mi->groups[cur_group].rates[cur_idx].prob_ewma;

  	cur_tp_avg = minstrel_ht_get_tp_avg(mi, cur_group, cur_idx, cur_prob);

  	do {

  		tmp_group = tp_list[j - 1] / MCS_GROUP_RATES;
  		tmp_idx = tp_list[j - 1] % MCS_GROUP_RATES;

  		tmp_prob = mi->groups[tmp_group].rates[tmp_idx].prob_ewma;

  		tmp_tp_avg = minstrel_ht_get_tp_avg(mi, tmp_group, tmp_idx,
  						    tmp_prob);

  		if (cur_tp_avg < tmp_tp_avg ||
  		    (cur_tp_avg == tmp_tp_avg && cur_prob <= tmp_prob))

  			break;
  		j--;
  	} while (j > 0);

  
  	if (j < MAX_THR_RATES - 1) {
  		memmove(&tp_list[j + 1], &tp_list[j], (sizeof(*tp_list) *
  		       (MAX_THR_RATES - (j + 1))));
  	}
  	if (j < MAX_THR_RATES)
  		tp_list[j] = index;
  }
  
  /*
   * Find and set the topmost probability rate per sta and per group
   */
  static void

  minstrel_ht_set_best_prob_rate(struct minstrel_ht_sta *mi, u16 index)

  {
  	struct minstrel_mcs_group_data *mg;

  	struct minstrel_rate_stats *mrs;

  	int tmp_group, tmp_idx, tmp_tp_avg, tmp_prob;
  	int max_tp_group, cur_tp_avg, cur_group, cur_idx;

  	int max_gpr_group, max_gpr_idx;
  	int max_gpr_tp_avg, max_gpr_prob;

  	cur_group = index / MCS_GROUP_RATES;
  	cur_idx = index % MCS_GROUP_RATES;

  	mg = &mi->groups[index / MCS_GROUP_RATES];

  	mrs = &mg->rates[index % MCS_GROUP_RATES];

  
  	tmp_group = mi->max_prob_rate / MCS_GROUP_RATES;
  	tmp_idx = mi->max_prob_rate % MCS_GROUP_RATES;

  	tmp_prob = mi->groups[tmp_group].rates[tmp_idx].prob_ewma;

  	tmp_tp_avg = minstrel_ht_get_tp_avg(mi, tmp_group, tmp_idx, tmp_prob);

  
  	/* if max_tp_rate[0] is from MCS_GROUP max_prob_rate get selected from
  	 * MCS_GROUP as well as CCK_GROUP rates do not allow aggregation */
  	max_tp_group = mi->max_tp_rate[0] / MCS_GROUP_RATES;
  	if((index / MCS_GROUP_RATES == MINSTREL_CCK_GROUP) &&
  	    (max_tp_group != MINSTREL_CCK_GROUP))
  		return;

  	max_gpr_group = mg->max_group_prob_rate / MCS_GROUP_RATES;
  	max_gpr_idx = mg->max_group_prob_rate % MCS_GROUP_RATES;
  	max_gpr_prob = mi->groups[max_gpr_group].rates[max_gpr_idx].prob_ewma;

  	if (mrs->prob_ewma > MINSTREL_FRAC(75, 100)) {

  		cur_tp_avg = minstrel_ht_get_tp_avg(mi, cur_group, cur_idx,
  						    mrs->prob_ewma);

  		if (cur_tp_avg > tmp_tp_avg)

  			mi->max_prob_rate = index;

  		max_gpr_tp_avg = minstrel_ht_get_tp_avg(mi, max_gpr_group,
  							max_gpr_idx,
  							max_gpr_prob);
  		if (cur_tp_avg > max_gpr_tp_avg)

  			mg->max_group_prob_rate = index;
  	} else {

  		if (mrs->prob_ewma > tmp_prob)

  			mi->max_prob_rate = index;

  		if (mrs->prob_ewma > max_gpr_prob)

  			mg->max_group_prob_rate = index;
  	}
  }
  
  
  /*
   * Assign new rate set per sta and use CCK rates only if the fastest
   * rate (max_tp_rate[0]) is from CCK group. This prohibits such sorted
   * rate sets where MCS and CCK rates are mixed, because CCK rates can
   * not use aggregation.
   */
  static void
  minstrel_ht_assign_best_tp_rates(struct minstrel_ht_sta *mi,

  				 u16 tmp_mcs_tp_rate[MAX_THR_RATES],
  				 u16 tmp_cck_tp_rate[MAX_THR_RATES])

  {

  	unsigned int tmp_group, tmp_idx, tmp_cck_tp, tmp_mcs_tp, tmp_prob;

  	int i;
  
  	tmp_group = tmp_cck_tp_rate[0] / MCS_GROUP_RATES;
  	tmp_idx = tmp_cck_tp_rate[0] % MCS_GROUP_RATES;

  	tmp_prob = mi->groups[tmp_group].rates[tmp_idx].prob_ewma;
  	tmp_cck_tp = minstrel_ht_get_tp_avg(mi, tmp_group, tmp_idx, tmp_prob);

  
  	tmp_group = tmp_mcs_tp_rate[0] / MCS_GROUP_RATES;
  	tmp_idx = tmp_mcs_tp_rate[0] % MCS_GROUP_RATES;

  	tmp_prob = mi->groups[tmp_group].rates[tmp_idx].prob_ewma;
  	tmp_mcs_tp = minstrel_ht_get_tp_avg(mi, tmp_group, tmp_idx, tmp_prob);

  
  	if (tmp_cck_tp > tmp_mcs_tp) {
  		for(i = 0; i < MAX_THR_RATES; i++) {
  			minstrel_ht_sort_best_tp_rates(mi, tmp_cck_tp_rate[i],
  						       tmp_mcs_tp_rate);
  		}
  	}
  
  }
  
  /*
   * Try to increase robustness of max_prob rate by decrease number of
   * streams if possible.
   */
  static inline void
  minstrel_ht_prob_rate_reduce_streams(struct minstrel_ht_sta *mi)
  {
  	struct minstrel_mcs_group_data *mg;

  	int tmp_max_streams, group, tmp_idx, tmp_prob;

  	int tmp_tp = 0;
  
  	tmp_max_streams = minstrel_mcs_groups[mi->max_tp_rate[0] /
  			  MCS_GROUP_RATES].streams;
  	for (group = 0; group < ARRAY_SIZE(minstrel_mcs_groups); group++) {
  		mg = &mi->groups[group];

  		if (!mi->supported[group] || group == MINSTREL_CCK_GROUP)

  			continue;

  
  		tmp_idx = mg->max_group_prob_rate % MCS_GROUP_RATES;

  		tmp_prob = mi->groups[group].rates[tmp_idx].prob_ewma;

  		if (tmp_tp < minstrel_ht_get_tp_avg(mi, group, tmp_idx, tmp_prob) &&

  		   (minstrel_mcs_groups[group].streams < tmp_max_streams)) {
  				mi->max_prob_rate = mg->max_group_prob_rate;

  				tmp_tp = minstrel_ht_get_tp_avg(mi, group,

  								tmp_idx,
  								tmp_prob);

  		}
  	}
  }
  
  /*

   * 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 75%, 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 *mrs;

  	int group, i, j, cur_prob;

  	u16 tmp_mcs_tp_rate[MAX_THR_RATES], tmp_group_tp_rate[MAX_THR_RATES];
  	u16 tmp_cck_tp_rate[MAX_THR_RATES], index;

  
  	if (mi->ampdu_packets > 0) {
  		mi->avg_ampdu_len = minstrel_ewma(mi->avg_ampdu_len,
  			MINSTREL_FRAC(mi->ampdu_len, mi->ampdu_packets), EWMA_LEVEL);
  		mi->ampdu_len = 0;
  		mi->ampdu_packets = 0;
  	}
  
  	mi->sample_slow = 0;
  	mi->sample_count = 0;

  	/* Initialize global rate indexes */
  	for(j = 0; j < MAX_THR_RATES; j++){
  		tmp_mcs_tp_rate[j] = 0;
  		tmp_cck_tp_rate[j] = 0;
  	}

  	/* Find best rate sets within all MCS groups*/
  	for (group = 0; group < ARRAY_SIZE(minstrel_mcs_groups); group++) {

  
  		mg = &mi->groups[group];

  		if (!mi->supported[group])

  			continue;

  		mi->sample_count++;

  		/* (re)Initialize group rate indexes */
  		for(j = 0; j < MAX_THR_RATES; j++)
  			tmp_group_tp_rate[j] = group;

  		for (i = 0; i < MCS_GROUP_RATES; i++) {

  			if (!(mi->supported[group] & BIT(i)))

  				continue;

  			index = MCS_GROUP_RATES * group + i;

  			mrs = &mg->rates[i];
  			mrs->retry_updated = false;
  			minstrel_calc_rate_stats(mrs);

  			cur_prob = mrs->prob_ewma;

  			if (minstrel_ht_get_tp_avg(mi, group, i, cur_prob) == 0)

  				continue;

  			/* Find max throughput rate set */
  			if (group != MINSTREL_CCK_GROUP) {
  				minstrel_ht_sort_best_tp_rates(mi, index,
  							       tmp_mcs_tp_rate);
  			} else if (group == MINSTREL_CCK_GROUP) {
  				minstrel_ht_sort_best_tp_rates(mi, index,
  							       tmp_cck_tp_rate);

  			}

  			/* Find max throughput rate set within a group */
  			minstrel_ht_sort_best_tp_rates(mi, index,
  						       tmp_group_tp_rate);

  			/* Find max probability rate per group and global */
  			minstrel_ht_set_best_prob_rate(mi, index);

  		}

  		memcpy(mg->max_group_tp_rate, tmp_group_tp_rate,
  		       sizeof(mg->max_group_tp_rate));

  	}

  	/* Assign new rate set per sta */
  	minstrel_ht_assign_best_tp_rates(mi, tmp_mcs_tp_rate, tmp_cck_tp_rate);
  	memcpy(mi->max_tp_rate, tmp_mcs_tp_rate, sizeof(mi->max_tp_rate));

  	/* Try to increase robustness of max_prob_rate*/
  	minstrel_ht_prob_rate_reduce_streams(mi);
  
  	/* try to sample all available rates during each interval */
  	mi->sample_count *= 8;

  #ifdef CONFIG_MAC80211_DEBUGFS
  	/* use fixed index if set */
  	if (mp->fixed_rate_idx != -1) {

  		for (i = 0; i < 4; i++)
  			mi->max_tp_rate[i] = mp->fixed_rate_idx;

  		mi->max_prob_rate = mp->fixed_rate_idx;
  	}
  #endif

  	/* Reset update timer */

  	mi->last_stats_update = jiffies;

  }
  
  static bool

  minstrel_ht_txstat_valid(struct minstrel_priv *mp, struct ieee80211_tx_rate *rate)

  {

  	if (rate->idx < 0)

  		return false;

  	if (!rate->count)

  		return false;

  	if (rate->flags & IEEE80211_TX_RC_MCS ||
  	    rate->flags & IEEE80211_TX_RC_VHT_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];

  }
  
  static void

  minstrel_set_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 (!mi->supported[mi->sample_group])

  			continue;
  
  		if (++mg->index >= MCS_GROUP_RATES) {
  			mg->index = 0;
  			if (++mg->column >= ARRAY_SIZE(sample_table))
  				mg->column = 0;
  		}
  		break;
  	}
  }
  
  static void

  minstrel_downgrade_rate(struct minstrel_ht_sta *mi, u16 *idx, bool primary)

  {
  	int group, orig_group;
  
  	orig_group = group = *idx / MCS_GROUP_RATES;
  	while (group > 0) {
  		group--;

  		if (!mi->supported[group])

  			continue;
  
  		if (minstrel_mcs_groups[group].streams >
  		    minstrel_mcs_groups[orig_group].streams)
  			continue;
  
  		if (primary)

  			*idx = mi->groups[group].max_group_tp_rate[0];

  		else

  			*idx = mi->groups[group].max_group_tp_rate[1];

  		break;
  	}
  }
  
  static void

  minstrel_aggr_check(struct ieee80211_sta *pubsta, struct sk_buff *skb)

  {
  	struct ieee80211_hdr *hdr = (struct ieee80211_hdr *) skb->data;
  	struct sta_info *sta = container_of(pubsta, struct sta_info, sta);
  	u16 tid;

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

  	if (unlikely(!ieee80211_is_data_qos(hdr->frame_control)))
  		return;

  	if (unlikely(skb->protocol == cpu_to_be16(ETH_P_PAE)))

  		return;
  
  	tid = *ieee80211_get_qos_ctl(hdr) & IEEE80211_QOS_CTL_TID_MASK;

  	if (likely(sta->ampdu_mlme.tid_tx[tid]))

  		return;

  	ieee80211_start_tx_ba_session(pubsta, tid, 0);

  }
  
  static void
  minstrel_ht_tx_status(void *priv, struct ieee80211_supported_band *sband,

                        void *priv_sta, struct ieee80211_tx_status *st)

  {

  	struct ieee80211_tx_info *info = st->info;

  	struct minstrel_ht_sta_priv *msp = priv_sta;
  	struct minstrel_ht_sta *mi = &msp->ht;

  	struct ieee80211_tx_rate *ar = info->status.rates;
  	struct minstrel_rate_stats *rate, *rate2;
  	struct minstrel_priv *mp = priv;

  	bool last, update = false;

  	int i;

  
  	if (!msp->is_ht)

  		return mac80211_minstrel.tx_status_ext(priv, sband,
  						       &msp->legacy, st);

  
  	/* This packet was aggregated but doesn't carry status info */
  	if ((info->flags & IEEE80211_TX_CTL_AMPDU) &&
  	    !(info->flags & IEEE80211_TX_STAT_AMPDU))
  		return;

  	if (!(info->flags & IEEE80211_TX_STAT_AMPDU)) {
  		info->status.ampdu_ack_len =
  			(info->flags & IEEE80211_TX_STAT_ACK ? 1 : 0);

  		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) {

  		mi->sample_wait = 16 + 2 * MINSTREL_TRUNC(mi->avg_ampdu_len);

  		mi->sample_tries = 1;

  		mi->sample_count--;
  	}

  	if (info->flags & IEEE80211_TX_CTL_RATE_CTRL_PROBE)

  		mi->sample_packets += info->status.ampdu_len;

  	last = !minstrel_ht_txstat_valid(mp, &ar[0]);

  	for (i = 0; !last; i++) {
  		last = (i == IEEE80211_TX_MAX_RATES - 1) ||

  		       !minstrel_ht_txstat_valid(mp, &ar[i + 1]);

  		rate = minstrel_ht_get_stats(mp, mi, &ar[i]);

  		if (last)

  			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[0]);

  	if (rate->attempts > 30 &&
  	    MINSTREL_FRAC(rate->success, rate->attempts) <

  	    MINSTREL_FRAC(20, 100)) {

  		minstrel_downgrade_rate(mi, &mi->max_tp_rate[0], true);

  		update = true;
  	}

  	rate2 = minstrel_get_ratestats(mi, mi->max_tp_rate[1]);

  	if (rate2->attempts > 30 &&
  	    MINSTREL_FRAC(rate2->success, rate2->attempts) <

  	    MINSTREL_FRAC(20, 100)) {

  		minstrel_downgrade_rate(mi, &mi->max_tp_rate[1], false);

  		update = true;
  	}

  	if (time_after(jiffies, mi->last_stats_update +
  				(mp->update_interval / 2 * HZ) / 1000)) {

  		update = true;

  		minstrel_ht_update_stats(mp, mi);

  	}

  
  	if (update)
  		minstrel_ht_update_rates(mp, mi);

  }
  
  static void
  minstrel_calc_retransmit(struct minstrel_priv *mp, struct minstrel_ht_sta *mi,
                           int index)
  {

  	struct minstrel_rate_stats *mrs;

  	const struct mcs_group *group;
  	unsigned int tx_time, tx_time_rtscts, tx_time_data;
  	unsigned int cw = mp->cw_min;

  	unsigned int ctime = 0;

  	unsigned int t_slot = 9; /* FIXME */
  	unsigned int ampdu_len = MINSTREL_TRUNC(mi->avg_ampdu_len);

  	unsigned int overhead = 0, overhead_rtscts = 0;

  	mrs = minstrel_get_ratestats(mi, index);
  	if (mrs->prob_ewma < MINSTREL_FRAC(1, 10)) {
  		mrs->retry_count = 1;
  		mrs->retry_count_rtscts = 1;

  		return;
  	}

  	mrs->retry_count = 2;
  	mrs->retry_count_rtscts = 2;
  	mrs->retry_updated = true;

  
  	group = &minstrel_mcs_groups[index / MCS_GROUP_RATES];

  	tx_time_data = group->duration[index % MCS_GROUP_RATES] * ampdu_len / 1000;

  
  	/* 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);

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

  	/* Total TX time for data and Contention after first 2 tries */

  	tx_time = ctime + 2 * (overhead + tx_time_data);
  	tx_time_rtscts = ctime + 2 * (overhead_rtscts + tx_time_data);

  
  	/* See how many more tries we can fit inside segment size */

  	do {

  		/* Contention time for this try */
  		ctime = (t_slot * cw) >> 1;
  		cw = min((cw << 1) | 1, mp->cw_max);
  
  		/* Total TX time after this try */

  		tx_time += ctime + overhead + tx_time_data;
  		tx_time_rtscts += ctime + overhead_rtscts + tx_time_data;

  		if (tx_time_rtscts < mp->segment_size)

  			mrs->retry_count_rtscts++;

  	} while ((tx_time < mp->segment_size) &&

  	         (++mrs->retry_count < mp->max_retry));

  }
  
  
  static void
  minstrel_ht_set_rate(struct minstrel_priv *mp, struct minstrel_ht_sta *mi,

                       struct ieee80211_sta_rates *ratetbl, int offset, int index)

  {
  	const struct mcs_group *group = &minstrel_mcs_groups[index / MCS_GROUP_RATES];

  	struct minstrel_rate_stats *mrs;

  	u8 idx;

  	u16 flags = group->flags;

  	mrs = minstrel_get_ratestats(mi, index);
  	if (!mrs->retry_updated)

  		minstrel_calc_retransmit(mp, mi, index);

  	if (mrs->prob_ewma < MINSTREL_FRAC(20, 100) || !mrs->retry_count) {

  		ratetbl->rate[offset].count = 2;
  		ratetbl->rate[offset].count_rts = 2;
  		ratetbl->rate[offset].count_cts = 2;
  	} else {

  		ratetbl->rate[offset].count = mrs->retry_count;
  		ratetbl->rate[offset].count_cts = mrs->retry_count;
  		ratetbl->rate[offset].count_rts = mrs->retry_count_rtscts;

  	}

  	if (index / MCS_GROUP_RATES == MINSTREL_CCK_GROUP)

  		idx = mp->cck_rates[index % ARRAY_SIZE(mp->cck_rates)];

  	else if (flags & IEEE80211_TX_RC_VHT_MCS)
  		idx = ((group->streams - 1) << 4) |
  		      ((index % MCS_GROUP_RATES) & 0xF);

  	else

  		idx = index % MCS_GROUP_RATES + (group->streams - 1) * 8;

  	/* enable RTS/CTS if needed:
  	 *  - if station is in dynamic SMPS (and streams > 1)
  	 *  - for fallback rates, to increase chances of getting through
  	 */

  	if (offset > 0 ||

  	    (mi->sta->smps_mode == IEEE80211_SMPS_DYNAMIC &&
  	     group->streams > 1)) {

  		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 inline int
  minstrel_ht_get_prob_ewma(struct minstrel_ht_sta *mi, int rate)
  {
  	int group = rate / MCS_GROUP_RATES;
  	rate %= MCS_GROUP_RATES;
  	return mi->groups[group].rates[rate].prob_ewma;
  }
  
  static int
  minstrel_ht_get_max_amsdu_len(struct minstrel_ht_sta *mi)
  {
  	int group = mi->max_prob_rate / MCS_GROUP_RATES;
  	const struct mcs_group *g = &minstrel_mcs_groups[group];
  	int rate = mi->max_prob_rate % MCS_GROUP_RATES;
  
  	/* Disable A-MSDU if max_prob_rate is bad */
  	if (mi->groups[group].rates[rate].prob_ewma < MINSTREL_FRAC(50, 100))
  		return 1;
  
  	/* If the rate is slower than single-stream MCS1, make A-MSDU limit small */
  	if (g->duration[rate] > MCS_DURATION(1, 0, 52))
  		return 500;
  
  	/*
  	 * If the rate is slower than single-stream MCS4, limit A-MSDU to usual
  	 * data packet size
  	 */
  	if (g->duration[rate] > MCS_DURATION(1, 0, 104))
  		return 1600;
  
  	/*
  	 * If the rate is slower than single-stream MCS7, or if the max throughput
  	 * rate success probability is less than 75%, limit A-MSDU to twice the usual
  	 * data packet size
  	 */
  	if (g->duration[rate] > MCS_DURATION(1, 0, 260) ||
  	    (minstrel_ht_get_prob_ewma(mi, mi->max_tp_rate[0]) <
  	     MINSTREL_FRAC(75, 100)))
  		return 3200;
  
  	/*
  	 * HT A-MPDU limits maximum MPDU size under BA agreement to 4095 bytes.
  	 * Since aggregation sessions are started/stopped without txq flush, use
  	 * the limit here to avoid the complexity of having to de-aggregate
  	 * packets in the queue.
  	 */
  	if (!mi->sta->vht_cap.vht_supported)
  		return IEEE80211_MAX_MPDU_LEN_HT_BA;
  
  	/* unlimited */
  	return 0;
  }

  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)

  		return;

  	/* Start with max_tp_rate[0] */
  	minstrel_ht_set_rate(mp, mi, rates, i++, mi->max_tp_rate[0]);

  
  	if (mp->hw->max_rates >= 3) {

  		/* At least 3 tx rates supported, use max_tp_rate[1] next */
  		minstrel_ht_set_rate(mp, mi, rates, i++, mi->max_tp_rate[1]);

  	}
  
  	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);

  	}

  	mi->sta->max_rc_amsdu_len = minstrel_ht_get_max_amsdu_len(mi);

  	rates->rate[i].idx = -1;
  	rate_control_set_rates(mp->hw, mi->sta, rates);

  }
  
  static inline int
  minstrel_get_duration(int index)
  {
  	const struct mcs_group *group = &minstrel_mcs_groups[index / MCS_GROUP_RATES];
  	return group->duration[index % MCS_GROUP_RATES];
  }
  
  static int
  minstrel_get_sample_rate(struct minstrel_priv *mp, struct minstrel_ht_sta *mi)
  {

  	struct minstrel_rate_stats *mrs;

  	struct minstrel_mcs_group_data *mg;

  	unsigned int sample_dur, sample_group, cur_max_tp_streams;

  	int tp_rate1, tp_rate2;

  	int sample_idx = 0;
  
  	if (mi->sample_wait > 0) {
  		mi->sample_wait--;
  		return -1;
  	}
  
  	if (!mi->sample_tries)
  		return -1;

  	sample_group = mi->sample_group;
  	mg = &mi->groups[sample_group];

  	sample_idx = sample_table[mg->column][mg->index];

  	minstrel_set_next_sample_idx(mi);

  	if (!(mi->supported[sample_group] & BIT(sample_idx)))

  		return -1;

  	mrs = &mg->rates[sample_idx];

  	sample_idx += sample_group * MCS_GROUP_RATES;

  	/* Set tp_rate1, tp_rate2 to the highest / second highest max_tp_rate */
  	if (minstrel_get_duration(mi->max_tp_rate[0]) >
  	    minstrel_get_duration(mi->max_tp_rate[1])) {
  		tp_rate1 = mi->max_tp_rate[1];
  		tp_rate2 = mi->max_tp_rate[0];
  	} else {
  		tp_rate1 = mi->max_tp_rate[0];
  		tp_rate2 = mi->max_tp_rate[1];
  	}

  	/*

  	 * Sampling might add some overhead (RTS, no aggregation)

  	 * to the frame. Hence, don't use sampling for the highest currently
  	 * used highest throughput or probability rate.

  	 */

  	if (sample_idx == mi->max_tp_rate[0] || sample_idx == mi->max_prob_rate)

  		return -1;

  	/*

  	 * Do not sample if the probability is already higher than 95%
  	 * to avoid wasting airtime.

  	 */

  	if (mrs->prob_ewma > MINSTREL_FRAC(95, 100))

  		return -1;

  
  	/*
  	 * Make sure that lower rates get sampled only occasionally,
  	 * if the link is working perfectly.
  	 */

  	cur_max_tp_streams = minstrel_mcs_groups[tp_rate1 /

  		MCS_GROUP_RATES].streams;

  	sample_dur = minstrel_get_duration(sample_idx);

  	if (sample_dur >= minstrel_get_duration(tp_rate2) &&

  	    (cur_max_tp_streams - 1 <

  	     minstrel_mcs_groups[sample_group].streams ||
  	     sample_dur >= minstrel_get_duration(mi->max_prob_rate))) {

  		if (mrs->sample_skipped < 20)

  			return -1;

  
  		if (mi->sample_slow++ > 2)

  			return -1;

  	}

  	mi->sample_tries--;

  
  	return sample_idx;

  }
  
  static void
  minstrel_ht_get_rate(void *priv, struct ieee80211_sta *sta, void *priv_sta,
                       struct ieee80211_tx_rate_control *txrc)
  {

  	const struct mcs_group *sample_group;

  	struct ieee80211_tx_info *info = IEEE80211_SKB_CB(txrc->skb);

  	struct ieee80211_tx_rate *rate = &info->status.rates[0];

  	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);

  	if (!(info->flags & IEEE80211_TX_CTL_AMPDU) &&
  	    mi->max_prob_rate / MCS_GROUP_RATES != MINSTREL_CCK_GROUP)
  		minstrel_aggr_check(sta, txrc->skb);

  	info->flags |= mi->tx_flags;

  #ifdef CONFIG_MAC80211_DEBUGFS
  	if (mp->fixed_rate_idx != -1)
  		return;
  #endif

  	/* Don't use EAPOL frames for sampling on non-mrr hw */
  	if (mp->hw->max_rates == 1 &&

  	    (info->control.flags & IEEE80211_TX_CTRL_PORT_CTRL_PROTO))

  		sample_idx = -1;
  	else
  		sample_idx = minstrel_get_sample_rate(mp, mi);

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

  
  	if (sample_idx < 0)
  		return;
  
  	sample_group = &minstrel_mcs_groups[sample_idx / MCS_GROUP_RATES];
  	info->flags |= IEEE80211_TX_CTL_RATE_CTRL_PROBE;

  	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];

  	} else if (sample_group->flags & IEEE80211_TX_RC_VHT_MCS) {
  		ieee80211_rate_set_vht(rate, sample_idx % MCS_GROUP_RATES,
  				       sample_group->streams);

  	} else {
  		rate->idx = sample_idx % MCS_GROUP_RATES +
  			    (sample_group->streams - 1) * 8;

  	}

  	rate->flags = sample_group->flags;

  }
  
  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 != NL80211_BAND_2GHZ)

  		return;

  	if (!ieee80211_hw_check(mp->hw, SUPPORTS_HT_CCK_RATES))

  		return;

  	mi->cck_supported = 0;
  	mi->cck_supported_short = 0;
  	for (i = 0; i < 4; i++) {
  		if (!rate_supported(sta, sband->band, mp->cck_rates[i]))
  			continue;
  
  		mi->cck_supported |= BIT(i);
  		if (sband->bitrates[i].flags & IEEE80211_RATE_SHORT_PREAMBLE)
  			mi->cck_supported_short |= BIT(i);
  	}

  	mi->supported[MINSTREL_CCK_GROUP] = mi->cck_supported;

  }
  
  static void

  minstrel_ht_update_caps(void *priv, struct ieee80211_supported_band *sband,

  			struct cfg80211_chan_def *chandef,

                          struct ieee80211_sta *sta, void *priv_sta)

  {
  	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;

  	struct ieee80211_sta_vht_cap *vht_cap = &sta->vht_cap;

  	struct sta_info *sinfo = container_of(sta, struct sta_info, sta);

  	int use_vht;

  	int n_supported = 0;

  	int ack_dur;
  	int stbc;
  	int i;
  
  	/* fall back to the old minstrel for legacy stations */

  	if (!sta->ht_cap.ht_supported)
  		goto use_legacy;

  	BUILD_BUG_ON(ARRAY_SIZE(minstrel_mcs_groups) != MINSTREL_GROUPS_NB);

  #ifdef CONFIG_MAC80211_RC_MINSTREL_VHT
  	if (vht_cap->vht_supported)
  		use_vht = vht_cap->vht_mcs.tx_mcs_map != cpu_to_le16(~0);
  	else
  #endif
  	use_vht = 0;

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

  
  	mi->sta = sta;

  	mi->last_stats_update = jiffies;

  	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;

  	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;

  	/* TODO tx_flags for vht - ATM the RC API is not fine-grained enough */
  	if (!use_vht) {
  		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++) {

  		u32 gflags = minstrel_mcs_groups[i].flags;

  		int bw, nss;

  		mi->supported[i] = 0;

  		if (i == MINSTREL_CCK_GROUP) {
  			minstrel_ht_update_cck(mp, mi, sband, sta);
  			continue;
  		}

  		if (gflags & IEEE80211_TX_RC_SHORT_GI) {
  			if (gflags & 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;
  			}

  		}

  		if (gflags & IEEE80211_TX_RC_40_MHZ_WIDTH &&

  		    sta->bandwidth < IEEE80211_STA_RX_BW_40)

  			continue;

  		nss = minstrel_mcs_groups[i].streams;

  		/* Mark MCS > 7 as unsupported if STA is in static SMPS mode */

  		if (sta->smps_mode == IEEE80211_SMPS_STATIC && nss > 1)
  			continue;
  
  		/* HT rate */
  		if (gflags & IEEE80211_TX_RC_MCS) {
  #ifdef CONFIG_MAC80211_RC_MINSTREL_VHT

  			if (use_vht && minstrel_vht_only)

  				continue;
  #endif

  			mi->supported[i] = mcs->rx_mask[nss - 1];
  			if (mi->supported[i])

  				n_supported++;
  			continue;
  		}
  
  		/* VHT rate */
  		if (!vht_cap->vht_supported ||
  		    WARN_ON(!(gflags & IEEE80211_TX_RC_VHT_MCS)) ||
  		    WARN_ON(gflags & IEEE80211_TX_RC_160_MHZ_WIDTH))

  			continue;

  		if (gflags & IEEE80211_TX_RC_80_MHZ_WIDTH) {
  			if (sta->bandwidth < IEEE80211_STA_RX_BW_80 ||
  			    ((gflags & IEEE80211_TX_RC_SHORT_GI) &&
  			     !(vht_cap->cap & IEEE80211_VHT_CAP_SHORT_GI_80))) {
  				continue;
  			}
  		}
  
  		if (gflags & IEEE80211_TX_RC_40_MHZ_WIDTH)
  			bw = BW_40;
  		else if (gflags & IEEE80211_TX_RC_80_MHZ_WIDTH)
  			bw = BW_80;
  		else
  			bw = BW_20;

  		mi->supported[i] = minstrel_get_valid_vht_rates(bw, nss,

  				vht_cap->vht_mcs.tx_mcs_map);

  		if (mi->supported[i])

  			n_supported++;

  	}

  
  	if (!n_supported)
  		goto use_legacy;

  	if (test_sta_flag(sinfo, WLAN_STA_SHORT_PREAMBLE))
  		mi->cck_supported_short |= mi->cck_supported_short << 4;

  	/* create an initial rate table with the lowest supported rates */

  	minstrel_ht_update_stats(mp, mi);

  	minstrel_ht_update_rates(mp, mi);

  	return;
  
  use_legacy:
  	msp->is_ht = false;
  	memset(&msp->legacy, 0, sizeof(msp->legacy));
  	msp->legacy.r = msp->ratelist;
  	msp->legacy.sample_table = msp->sample_table;

  	return mac80211_minstrel.rate_init(priv, sband, chandef, sta,
  					   &msp->legacy);

  }
  
  static void
  minstrel_ht_rate_init(void *priv, struct ieee80211_supported_band *sband,

  		      struct cfg80211_chan_def *chandef,

                        struct ieee80211_sta *sta, void *priv_sta)
  {

  	minstrel_ht_update_caps(priv, sband, chandef, sta, priv_sta);

  }
  
  static void
  minstrel_ht_rate_update(void *priv, struct ieee80211_supported_band *sband,

  			struct cfg80211_chan_def *chandef,

                          struct ieee80211_sta *sta, void *priv_sta,

                          u32 changed)

  {

  	minstrel_ht_update_caps(priv, sband, chandef, sta, priv_sta);

  }
  
  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 < NUM_NL80211_BANDS; i++) {

  		sband = hw->wiphy->bands[i];
  		if (sband && sband->n_bitrates > max_rates)
  			max_rates = sband->n_bitrates;
  	}

  	msp = kzalloc(sizeof(*msp), gfp);

  	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:

  	kfree(msp->ratelist);

  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 u32 minstrel_ht_get_expected_throughput(void *priv_sta)
  {
  	struct minstrel_ht_sta_priv *msp = priv_sta;
  	struct minstrel_ht_sta *mi = &msp->ht;

  	int i, j, prob, tp_avg;

  
  	if (!msp->is_ht)
  		return mac80211_minstrel.get_expected_throughput(priv_sta);

  	i = mi->max_tp_rate[0] / MCS_GROUP_RATES;
  	j = mi->max_tp_rate[0] % MCS_GROUP_RATES;

  	prob = mi->groups[i].rates[j].prob_ewma;

  	/* convert tp_avg from pkt per second in kbps */

  	tp_avg = minstrel_ht_get_tp_avg(mi, i, j, prob) * 10;
  	tp_avg = tp_avg * AVG_PKT_SIZE * 8 / 1024;

  
  	return tp_avg;

  }

  static const struct rate_control_ops mac80211_minstrel_ht = {

  	.name = "minstrel_ht",

  	.tx_status_ext = 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

  	.get_expected_throughput = minstrel_ht_get_expected_throughput,

  };

  static void __init 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++) {

  		prandom_bytes(rnd, sizeof(rnd));

  		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);
  }