path: root/net/mac80211/rc80211_minstrel_ht.c

/*
 * 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, _s)				\
	[GROUP_IDX(_streams, _sgi, _ht40)] = {				\
	.streams = _streams,						\
	.shift = _s,							\
	.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) >> _s,	\
		MCS_DURATION(_streams, _sgi, _ht40 ? 108 : 52) >> _s,	\
		MCS_DURATION(_streams, _sgi, _ht40 ? 162 : 78) >> _s,	\
		MCS_DURATION(_streams, _sgi, _ht40 ? 216 : 104) >> _s,	\
		MCS_DURATION(_streams, _sgi, _ht40 ? 324 : 156) >> _s,	\
		MCS_DURATION(_streams, _sgi, _ht40 ? 432 : 208) >> _s,	\
		MCS_DURATION(_streams, _sgi, _ht40 ? 486 : 234) >> _s,	\
		MCS_DURATION(_streams, _sgi, _ht40 ? 540 : 260) >> _s	\
	}								\
}

#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, _s)				\
	[VHT_GROUP_IDX(_streams, _sgi, _bw)] = {			\
	.streams = _streams,						\
	.shift = _s,							\
	.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)) >> _s,	\
		MCS_DURATION(_streams, _sgi,				\
			     BW2VBPS(_bw,  234, 108,  52)) >> _s,	\
		MCS_DURATION(_streams, _sgi,				\
			     BW2VBPS(_bw,  351, 162,  78)) >> _s,	\
		MCS_DURATION(_streams, _sgi,				\
			     BW2VBPS(_bw,  468, 216, 104)) >> _s,	\
		MCS_DURATION(_streams, _sgi,				\
			     BW2VBPS(_bw,  702, 324, 156)) >> _s,	\
		MCS_DURATION(_streams, _sgi,				\
			     BW2VBPS(_bw,  936, 432, 208)) >> _s,	\
		MCS_DURATION(_streams, _sgi,				\
			     BW2VBPS(_bw, 1053, 486, 234)) >> _s,	\
		MCS_DURATION(_streams, _sgi,				\
			     BW2VBPS(_bw, 1170, 540, 260)) >> _s,	\
		MCS_DURATION(_streams, _sgi,				\
			     BW2VBPS(_bw, 1404, 648, 312)) >> _s,	\
		MCS_DURATION(_streams, _sgi,				\
			     BW2VBPS(_bw, 1560, 720, 346)) >> _s	\
	}								\
}

#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, _s)			\
	CCK_ACK_DURATION(10, _short) >> _s,		\
	CCK_ACK_DURATION(20, _short) >> _s,		\
	CCK_ACK_DURATION(55, _short) >> _s,		\
	CCK_ACK_DURATION(110, _short) >> _s

#define CCK_GROUP(_s)					\
	[MINSTREL_CCK_GROUP] = {			\
		.streams = 1,				\
		.flags = 0,				\
		.shift = _s,				\
		.duration = {				\
			CCK_DURATION_LIST(false, _s),	\
			CCK_DURATION_LIST(true, _s)	\
		}					\
	}

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.");

/*
 * 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, 5),
	MCS_GROUP(2, 0, BW_20, 4),
	MCS_GROUP(3, 0, BW_20, 4),

	MCS_GROUP(1, 1, BW_20, 5),
	MCS_GROUP(2, 1, BW_20, 4),
	MCS_GROUP(3, 1, BW_20, 4),

	MCS_GROUP(1, 0, BW_40, 4),
	MCS_GROUP(2, 0, BW_40, 4),
	MCS_GROUP(3, 0, BW_40, 4),

	MCS_GROUP(1, 1, BW_40, 4),
	MCS_GROUP(2, 1, BW_40, 4),
	MCS_GROUP(3, 1, BW_40, 4),

	CCK_GROUP(8),

	VHT_GROUP(1, 0, BW_20, 5),
	VHT_GROUP(2, 0, BW_20, 4),
	VHT_GROUP(3, 0, BW_20, 4),

	VHT_GROUP(1, 1, BW_20, 5),
	VHT_GROUP(2, 1, BW_20, 4),
	VHT_GROUP(3, 1, BW_20, 4),

	VHT_GROUP(1, 0, BW_40, 4),
	VHT_GROUP(2, 0, BW_40, 4),
	VHT_GROUP(3, 0, BW_40, 4),

	VHT_GROUP(1, 1, BW_40, 4),
	VHT_GROUP(2, 1, BW_40, 4),
	VHT_GROUP(3, 1, BW_40, 4),

	VHT_GROUP(1, 0, BW_80, 4),
	VHT_GROUP(2, 0, BW_80, 4),
	VHT_GROUP(3, 0, BW_80, 4),

	VHT_GROUP(1, 1, BW_80, 4),
	VHT_GROUP(2, 1, BW_80, 4),
	VHT_GROUP(3, 1, BW_80, 4),
};

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