mt76: track rx airtime for airtime fairness and survey

Report total rx airtime for valid stations as BSS rx time in survey

mt7615 is left out for now, it will be supported later by reading
hardware counters instead of calculating airtime in software

Signed-off-by: Felix Fietkau <nbd@nbd.name>

1 files changed, 278 insertions, 0 deletions

diff --git a/drivers/net/wireless/mediatek/mt76/airtime.c b/drivers/net/wireless/mediatek/mt76/airtime.c
new file mode 100644
index 000000000000..d5bc4d713a88
--- /dev/null
+++ b/drivers/net/wireless/mediatek/mt76/airtime.c
@@ -0,0 +1,278 @@
+// SPDX-License-Identifier: ISC
+/*
+ * Copyright (C) 2019 Felix Fietkau <nbd@nbd.name>
+ */
+
+#include "mt76.h"
+
+#define AVG_PKT_SIZE	1024
+
+/* Number of bits for an average sized packet */
+#define MCS_NBITS (AVG_PKT_SIZE << 3)
+
+/* Number of symbols for a packet with (bps) bits per symbol */
+#define MCS_NSYMS(bps) DIV_ROUND_UP(MCS_NBITS, (bps))
+
+/* Transmission time (1024 usec) for a packet containing (syms) * symbols */
+#define MCS_SYMBOL_TIME(sgi, syms)					\
+	(sgi ?								\
+	  ((syms) * 18 * 1024 + 4 * 1024) / 5 :	/* syms * 3.6 us */	\
+	  ((syms) * 1024) << 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)))
+
+#define BW_20			0
+#define BW_40			1
+#define BW_80			2
+
+/*
+ * Define group sort order: HT40 -> SGI -> #streams
+ */
+#define MT_MAX_STREAMS		4
+#define MT_HT_STREAM_GROUPS	4 /* BW(=2) * SGI(=2) */
+#define MT_VHT_STREAM_GROUPS	6 /* BW(=3) * SGI(=2) */
+
+#define MT_HT_GROUPS_NB	(MT_MAX_STREAMS *		\
+				 MT_HT_STREAM_GROUPS)
+#define MT_VHT_GROUPS_NB	(MT_MAX_STREAMS *		\
+				 MT_VHT_STREAM_GROUPS)
+#define MT_GROUPS_NB	(MT_HT_GROUPS_NB +	\
+				 MT_VHT_GROUPS_NB)
+
+#define MT_HT_GROUP_0	0
+#define MT_VHT_GROUP_0	(MT_HT_GROUP_0 + MT_HT_GROUPS_NB)
+
+#define MCS_GROUP_RATES		10
+
+#define HT_GROUP_IDX(_streams, _sgi, _ht40)	\
+	MT_HT_GROUP_0 +			\
+	MT_MAX_STREAMS * 2 * _ht40 +	\
+	MT_MAX_STREAMS * _sgi +	\
+	_streams - 1
+
+#define _MAX(a, b) (((a)>(b))?(a):(b))
+
+#define GROUP_SHIFT(duration)						\
+	_MAX(0, 16 - __builtin_clz(duration))
+
+/* MCS rate information for an MCS group */
+#define __MCS_GROUP(_streams, _sgi, _ht40, _s)				\
+	[HT_GROUP_IDX(_streams, _sgi, _ht40)] = {			\
+	.shift = _s,							\
+	.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 MCS_GROUP_SHIFT(_streams, _sgi, _ht40)				\
+	GROUP_SHIFT(MCS_DURATION(_streams, _sgi, _ht40 ? 54 : 26))
+
+#define MCS_GROUP(_streams, _sgi, _ht40)				\
+	__MCS_GROUP(_streams, _sgi, _ht40,				\
+		    MCS_GROUP_SHIFT(_streams, _sgi, _ht40))
+
+#define VHT_GROUP_IDX(_streams, _sgi, _bw)				\
+	(MT_VHT_GROUP_0 +						\
+	 MT_MAX_STREAMS * 2 * (_bw) +				\
+	 MT_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)] = {			\
+	.shift = _s,							\
+	.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 VHT_GROUP_SHIFT(_streams, _sgi, _bw)				\
+	GROUP_SHIFT(MCS_DURATION(_streams, _sgi,			\
+				 BW2VBPS(_bw,  117,  54,  26)))
+
+#define VHT_GROUP(_streams, _sgi, _bw)					\
+	__VHT_GROUP(_streams, _sgi, _bw,				\
+		    VHT_GROUP_SHIFT(_streams, _sgi, _bw))
+
+struct mcs_group {
+	u8 shift;
+	u16 duration[MCS_GROUP_RATES];
+};
+
+static const struct mcs_group airtime_mcs_groups[] = {
+	MCS_GROUP(1, 0, BW_20),
+	MCS_GROUP(2, 0, BW_20),
+	MCS_GROUP(3, 0, BW_20),
+	MCS_GROUP(4, 0, BW_20),
+
+	MCS_GROUP(1, 1, BW_20),
+	MCS_GROUP(2, 1, BW_20),
+	MCS_GROUP(3, 1, BW_20),
+	MCS_GROUP(4, 1, BW_20),
+
+	MCS_GROUP(1, 0, BW_40),
+	MCS_GROUP(2, 0, BW_40),
+	MCS_GROUP(3, 0, BW_40),
+	MCS_GROUP(4, 0, BW_40),
+
+	MCS_GROUP(1, 1, BW_40),
+	MCS_GROUP(2, 1, BW_40),
+	MCS_GROUP(3, 1, BW_40),
+	MCS_GROUP(4, 1, BW_40),
+
+	VHT_GROUP(1, 0, BW_20),
+	VHT_GROUP(2, 0, BW_20),
+	VHT_GROUP(3, 0, BW_20),
+	VHT_GROUP(4, 0, BW_20),
+
+	VHT_GROUP(1, 1, BW_20),
+	VHT_GROUP(2, 1, BW_20),
+	VHT_GROUP(3, 1, BW_20),
+	VHT_GROUP(4, 1, BW_20),
+
+	VHT_GROUP(1, 0, BW_40),
+	VHT_GROUP(2, 0, BW_40),
+	VHT_GROUP(3, 0, BW_40),
+	VHT_GROUP(4, 0, BW_40),
+
+	VHT_GROUP(1, 1, BW_40),
+	VHT_GROUP(2, 1, BW_40),
+	VHT_GROUP(3, 1, BW_40),
+	VHT_GROUP(4, 1, BW_40),
+
+	VHT_GROUP(1, 0, BW_80),
+	VHT_GROUP(2, 0, BW_80),
+	VHT_GROUP(3, 0, BW_80),
+	VHT_GROUP(4, 0, BW_80),
+
+	VHT_GROUP(1, 1, BW_80),
+	VHT_GROUP(2, 1, BW_80),
+	VHT_GROUP(3, 1, BW_80),
+	VHT_GROUP(4, 1, BW_80),
+};
+
+static u32
+mt76_calc_legacy_rate_duration(const struct ieee80211_rate *rate, bool short_pre,
+			       int len)
+{
+	u32 duration;
+
+	switch (rate->hw_value >> 8) {
+	case MT_PHY_TYPE_CCK:
+		duration = 144 + 48; /* preamble + PLCP */
+		if (short_pre)
+			duration >>= 1;
+
+		duration += 10; /* SIFS */
+		break;
+	case MT_PHY_TYPE_OFDM:
+		duration = 20 + 16; /* premable + SIFS */
+		break;
+	default:
+		WARN_ON_ONCE(1);
+		return 0;
+	}
+
+	len <<= 3;
+	duration += (len * 10) / rate->bitrate;
+
+	return duration;
+}
+
+u32 mt76_calc_rx_airtime(struct mt76_dev *dev, struct mt76_rx_status *status,
+			 int len)
+{
+	struct ieee80211_supported_band *sband;
+	const struct ieee80211_rate *rate;
+	bool sgi = status->enc_flags & RX_ENC_FLAG_SHORT_GI;
+	bool sp = status->enc_flags & RX_ENC_FLAG_SHORTPRE;
+	int bw, streams;
+	u32 duration;
+	int group, idx;
+
+	switch (status->bw) {
+	case RATE_INFO_BW_20:
+		bw = BW_20;
+		break;
+	case RATE_INFO_BW_40:
+		bw = BW_40;
+		break;
+	case RATE_INFO_BW_80:
+		bw = BW_80;
+		break;
+	default:
+		WARN_ON_ONCE(1);
+		return 0;
+	}
+
+	switch (status->encoding) {
+	case RX_ENC_LEGACY:
+		if (WARN_ON_ONCE(status->band > NL80211_BAND_5GHZ))
+			return 0;
+
+		sband = dev->hw->wiphy->bands[status->band];
+		if (!sband || status->rate_idx > sband->n_bitrates)
+			return 0;
+
+		rate = &sband->bitrates[status->rate_idx];
+
+		return mt76_calc_legacy_rate_duration(rate, sp, len);
+	case RX_ENC_VHT:
+		streams = status->nss;
+		idx = status->rate_idx;
+		group = VHT_GROUP_IDX(streams, sgi, bw);
+		break;
+	case RX_ENC_HT:
+		streams = ((status->rate_idx >> 3) & 3) + 1;
+		idx = status->rate_idx & 7;
+		group = HT_GROUP_IDX(streams, sgi, bw);
+		break;
+	default:
+		WARN_ON_ONCE(1);
+		return 0;
+	}
+
+	if (WARN_ON_ONCE(streams > 4))
+		return 0;
+
+	duration = airtime_mcs_groups[group].duration[idx];
+	duration <<= airtime_mcs_groups[group].shift;
+	duration *= len;
+	duration /= AVG_PKT_SIZE;
+	duration /= 1024;
+
+	duration += 36 + (streams << 2);
+
+	return duration;
+}