1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3  * Copyright (C) 2010-2013 Felix Fietkau <nbd@openwrt.org>
4  * Copyright (C) 2019-2022 Intel Corporation
5  */
6 #include <linux/netdevice.h>
7 #include <linux/types.h>
8 #include <linux/skbuff.h>
9 #include <linux/debugfs.h>
10 #include <linux/random.h>
11 #include <linux/moduleparam.h>
12 #include <linux/ieee80211.h>
13 #include <linux/minmax.h>
14 #include <net/mac80211.h>
15 #include "rate.h"
16 #include "sta_info.h"
17 #include "rc80211_minstrel_ht.h"
18 
19 #define AVG_AMPDU_SIZE	16
20 #define AVG_PKT_SIZE	1200
21 
22 /* Number of bits for an average sized packet */
23 #define MCS_NBITS ((AVG_PKT_SIZE * AVG_AMPDU_SIZE) << 3)
24 
25 /* Number of symbols for a packet with (bps) bits per symbol */
26 #define MCS_NSYMS(bps) DIV_ROUND_UP(MCS_NBITS, (bps))
27 
28 /* Transmission time (nanoseconds) for a packet containing (syms) symbols */
29 #define MCS_SYMBOL_TIME(sgi, syms)					\
30 	(sgi ?								\
31 	  ((syms) * 18000 + 4000) / 5 :	/* syms * 3.6 us */		\
32 	  ((syms) * 1000) << 2		/* syms * 4 us */		\
33 	)
34 
35 /* Transmit duration for the raw data part of an average sized packet */
36 #define MCS_DURATION(streams, sgi, bps) \
37 	(MCS_SYMBOL_TIME(sgi, MCS_NSYMS((streams) * (bps))) / AVG_AMPDU_SIZE)
38 
39 #define BW_20			0
40 #define BW_40			1
41 #define BW_80			2
42 
43 /*
44  * Define group sort order: HT40 -> SGI -> #streams
45  */
46 #define GROUP_IDX(_streams, _sgi, _ht40)	\
47 	MINSTREL_HT_GROUP_0 +			\
48 	MINSTREL_MAX_STREAMS * 2 * _ht40 +	\
49 	MINSTREL_MAX_STREAMS * _sgi +	\
50 	_streams - 1
51 
52 #define _MAX(a, b) (((a)>(b))?(a):(b))
53 
54 #define GROUP_SHIFT(duration)						\
55 	_MAX(0, 16 - __builtin_clz(duration))
56 
57 /* MCS rate information for an MCS group */
58 #define __MCS_GROUP(_streams, _sgi, _ht40, _s)				\
59 	[GROUP_IDX(_streams, _sgi, _ht40)] = {				\
60 	.streams = _streams,						\
61 	.shift = _s,							\
62 	.bw = _ht40,							\
63 	.flags =							\
64 		IEEE80211_TX_RC_MCS |					\
65 		(_sgi ? IEEE80211_TX_RC_SHORT_GI : 0) |			\
66 		(_ht40 ? IEEE80211_TX_RC_40_MHZ_WIDTH : 0),		\
67 	.duration = {							\
68 		MCS_DURATION(_streams, _sgi, _ht40 ? 54 : 26) >> _s,	\
69 		MCS_DURATION(_streams, _sgi, _ht40 ? 108 : 52) >> _s,	\
70 		MCS_DURATION(_streams, _sgi, _ht40 ? 162 : 78) >> _s,	\
71 		MCS_DURATION(_streams, _sgi, _ht40 ? 216 : 104) >> _s,	\
72 		MCS_DURATION(_streams, _sgi, _ht40 ? 324 : 156) >> _s,	\
73 		MCS_DURATION(_streams, _sgi, _ht40 ? 432 : 208) >> _s,	\
74 		MCS_DURATION(_streams, _sgi, _ht40 ? 486 : 234) >> _s,	\
75 		MCS_DURATION(_streams, _sgi, _ht40 ? 540 : 260) >> _s	\
76 	}								\
77 }
78 
79 #define MCS_GROUP_SHIFT(_streams, _sgi, _ht40)				\
80 	GROUP_SHIFT(MCS_DURATION(_streams, _sgi, _ht40 ? 54 : 26))
81 
82 #define MCS_GROUP(_streams, _sgi, _ht40)				\
83 	__MCS_GROUP(_streams, _sgi, _ht40,				\
84 		    MCS_GROUP_SHIFT(_streams, _sgi, _ht40))
85 
86 #define VHT_GROUP_IDX(_streams, _sgi, _bw)				\
87 	(MINSTREL_VHT_GROUP_0 +						\
88 	 MINSTREL_MAX_STREAMS * 2 * (_bw) +				\
89 	 MINSTREL_MAX_STREAMS * (_sgi) +				\
90 	 (_streams) - 1)
91 
92 #define BW2VBPS(_bw, r3, r2, r1)					\
93 	(_bw == BW_80 ? r3 : _bw == BW_40 ? r2 : r1)
94 
95 #define __VHT_GROUP(_streams, _sgi, _bw, _s)				\
96 	[VHT_GROUP_IDX(_streams, _sgi, _bw)] = {			\
97 	.streams = _streams,						\
98 	.shift = _s,							\
99 	.bw = _bw,							\
100 	.flags =							\
101 		IEEE80211_TX_RC_VHT_MCS |				\
102 		(_sgi ? IEEE80211_TX_RC_SHORT_GI : 0) |			\
103 		(_bw == BW_80 ? IEEE80211_TX_RC_80_MHZ_WIDTH :		\
104 		 _bw == BW_40 ? IEEE80211_TX_RC_40_MHZ_WIDTH : 0),	\
105 	.duration = {							\
106 		MCS_DURATION(_streams, _sgi,				\
107 			     BW2VBPS(_bw,  117,  54,  26)) >> _s,	\
108 		MCS_DURATION(_streams, _sgi,				\
109 			     BW2VBPS(_bw,  234, 108,  52)) >> _s,	\
110 		MCS_DURATION(_streams, _sgi,				\
111 			     BW2VBPS(_bw,  351, 162,  78)) >> _s,	\
112 		MCS_DURATION(_streams, _sgi,				\
113 			     BW2VBPS(_bw,  468, 216, 104)) >> _s,	\
114 		MCS_DURATION(_streams, _sgi,				\
115 			     BW2VBPS(_bw,  702, 324, 156)) >> _s,	\
116 		MCS_DURATION(_streams, _sgi,				\
117 			     BW2VBPS(_bw,  936, 432, 208)) >> _s,	\
118 		MCS_DURATION(_streams, _sgi,				\
119 			     BW2VBPS(_bw, 1053, 486, 234)) >> _s,	\
120 		MCS_DURATION(_streams, _sgi,				\
121 			     BW2VBPS(_bw, 1170, 540, 260)) >> _s,	\
122 		MCS_DURATION(_streams, _sgi,				\
123 			     BW2VBPS(_bw, 1404, 648, 312)) >> _s,	\
124 		MCS_DURATION(_streams, _sgi,				\
125 			     BW2VBPS(_bw, 1560, 720, 346)) >> _s	\
126 	}								\
127 }
128 
129 #define VHT_GROUP_SHIFT(_streams, _sgi, _bw)				\
130 	GROUP_SHIFT(MCS_DURATION(_streams, _sgi,			\
131 				 BW2VBPS(_bw,  117,  54,  26)))
132 
133 #define VHT_GROUP(_streams, _sgi, _bw)					\
134 	__VHT_GROUP(_streams, _sgi, _bw,				\
135 		    VHT_GROUP_SHIFT(_streams, _sgi, _bw))
136 
137 #define CCK_DURATION(_bitrate, _short)			\
138 	(1000 * (10 /* SIFS */ +			\
139 	 (_short ? 72 + 24 : 144 + 48) +		\
140 	 (8 * (AVG_PKT_SIZE + 4) * 10) / (_bitrate)))
141 
142 #define CCK_DURATION_LIST(_short, _s)			\
143 	CCK_DURATION(10, _short) >> _s,			\
144 	CCK_DURATION(20, _short) >> _s,			\
145 	CCK_DURATION(55, _short) >> _s,			\
146 	CCK_DURATION(110, _short) >> _s
147 
148 #define __CCK_GROUP(_s)					\
149 	[MINSTREL_CCK_GROUP] = {			\
150 		.streams = 1,				\
151 		.flags = 0,				\
152 		.shift = _s,				\
153 		.duration = {				\
154 			CCK_DURATION_LIST(false, _s),	\
155 			CCK_DURATION_LIST(true, _s)	\
156 		}					\
157 	}
158 
159 #define CCK_GROUP_SHIFT					\
160 	GROUP_SHIFT(CCK_DURATION(10, false))
161 
162 #define CCK_GROUP __CCK_GROUP(CCK_GROUP_SHIFT)
163 
164 #define OFDM_DURATION(_bitrate)				\
165 	(1000 * (16 /* SIFS + signal ext */ +		\
166 	 16 /* T_PREAMBLE */ +				\
167 	 4 /* T_SIGNAL */ +				\
168 	 4 * (((16 + 80 * (AVG_PKT_SIZE + 4) + 6) /	\
169 	      ((_bitrate) * 4)))))
170 
171 #define OFDM_DURATION_LIST(_s)				\
172 	OFDM_DURATION(60) >> _s,			\
173 	OFDM_DURATION(90) >> _s,			\
174 	OFDM_DURATION(120) >> _s,			\
175 	OFDM_DURATION(180) >> _s,			\
176 	OFDM_DURATION(240) >> _s,			\
177 	OFDM_DURATION(360) >> _s,			\
178 	OFDM_DURATION(480) >> _s,			\
179 	OFDM_DURATION(540) >> _s
180 
181 #define __OFDM_GROUP(_s)				\
182 	[MINSTREL_OFDM_GROUP] = {			\
183 		.streams = 1,				\
184 		.flags = 0,				\
185 		.shift = _s,				\
186 		.duration = {				\
187 			OFDM_DURATION_LIST(_s),		\
188 		}					\
189 	}
190 
191 #define OFDM_GROUP_SHIFT				\
192 	GROUP_SHIFT(OFDM_DURATION(60))
193 
194 #define OFDM_GROUP __OFDM_GROUP(OFDM_GROUP_SHIFT)
195 
196 
197 static bool minstrel_vht_only = true;
198 module_param(minstrel_vht_only, bool, 0644);
199 MODULE_PARM_DESC(minstrel_vht_only,
200 		 "Use only VHT rates when VHT is supported by sta.");
201 
202 /*
203  * To enable sufficiently targeted rate sampling, MCS rates are divided into
204  * groups, based on the number of streams and flags (HT40, SGI) that they
205  * use.
206  *
207  * Sortorder has to be fixed for GROUP_IDX macro to be applicable:
208  * BW -> SGI -> #streams
209  */
210 const struct mcs_group minstrel_mcs_groups[] = {
211 	MCS_GROUP(1, 0, BW_20),
212 	MCS_GROUP(2, 0, BW_20),
213 	MCS_GROUP(3, 0, BW_20),
214 	MCS_GROUP(4, 0, BW_20),
215 
216 	MCS_GROUP(1, 1, BW_20),
217 	MCS_GROUP(2, 1, BW_20),
218 	MCS_GROUP(3, 1, BW_20),
219 	MCS_GROUP(4, 1, BW_20),
220 
221 	MCS_GROUP(1, 0, BW_40),
222 	MCS_GROUP(2, 0, BW_40),
223 	MCS_GROUP(3, 0, BW_40),
224 	MCS_GROUP(4, 0, BW_40),
225 
226 	MCS_GROUP(1, 1, BW_40),
227 	MCS_GROUP(2, 1, BW_40),
228 	MCS_GROUP(3, 1, BW_40),
229 	MCS_GROUP(4, 1, BW_40),
230 
231 	CCK_GROUP,
232 	OFDM_GROUP,
233 
234 	VHT_GROUP(1, 0, BW_20),
235 	VHT_GROUP(2, 0, BW_20),
236 	VHT_GROUP(3, 0, BW_20),
237 	VHT_GROUP(4, 0, BW_20),
238 
239 	VHT_GROUP(1, 1, BW_20),
240 	VHT_GROUP(2, 1, BW_20),
241 	VHT_GROUP(3, 1, BW_20),
242 	VHT_GROUP(4, 1, BW_20),
243 
244 	VHT_GROUP(1, 0, BW_40),
245 	VHT_GROUP(2, 0, BW_40),
246 	VHT_GROUP(3, 0, BW_40),
247 	VHT_GROUP(4, 0, BW_40),
248 
249 	VHT_GROUP(1, 1, BW_40),
250 	VHT_GROUP(2, 1, BW_40),
251 	VHT_GROUP(3, 1, BW_40),
252 	VHT_GROUP(4, 1, BW_40),
253 
254 	VHT_GROUP(1, 0, BW_80),
255 	VHT_GROUP(2, 0, BW_80),
256 	VHT_GROUP(3, 0, BW_80),
257 	VHT_GROUP(4, 0, BW_80),
258 
259 	VHT_GROUP(1, 1, BW_80),
260 	VHT_GROUP(2, 1, BW_80),
261 	VHT_GROUP(3, 1, BW_80),
262 	VHT_GROUP(4, 1, BW_80),
263 };
264 
265 const s16 minstrel_cck_bitrates[4] = { 10, 20, 55, 110 };
266 const s16 minstrel_ofdm_bitrates[8] = { 60, 90, 120, 180, 240, 360, 480, 540 };
267 static u8 sample_table[SAMPLE_COLUMNS][MCS_GROUP_RATES] __read_mostly;
268 static const u8 minstrel_sample_seq[] = {
269 	MINSTREL_SAMPLE_TYPE_INC,
270 	MINSTREL_SAMPLE_TYPE_JUMP,
271 	MINSTREL_SAMPLE_TYPE_INC,
272 	MINSTREL_SAMPLE_TYPE_JUMP,
273 	MINSTREL_SAMPLE_TYPE_INC,
274 	MINSTREL_SAMPLE_TYPE_SLOW,
275 };
276 
277 static void
278 minstrel_ht_update_rates(struct minstrel_priv *mp, struct minstrel_ht_sta *mi);
279 
280 /*
281  * Some VHT MCSes are invalid (when Ndbps / Nes is not an integer)
282  * e.g for MCS9@20MHzx1Nss: Ndbps=8x52*(5/6) Nes=1
283  *
284  * Returns the valid mcs map for struct minstrel_mcs_group_data.supported
285  */
286 static u16
287 minstrel_get_valid_vht_rates(int bw, int nss, __le16 mcs_map)
288 {
289 	u16 mask = 0;
290 
291 	if (bw == BW_20) {
292 		if (nss != 3 && nss != 6)
293 			mask = BIT(9);
294 	} else if (bw == BW_80) {
295 		if (nss == 3 || nss == 7)
296 			mask = BIT(6);
297 		else if (nss == 6)
298 			mask = BIT(9);
299 	} else {
300 		WARN_ON(bw != BW_40);
301 	}
302 
303 	switch ((le16_to_cpu(mcs_map) >> (2 * (nss - 1))) & 3) {
304 	case IEEE80211_VHT_MCS_SUPPORT_0_7:
305 		mask |= 0x300;
306 		break;
307 	case IEEE80211_VHT_MCS_SUPPORT_0_8:
308 		mask |= 0x200;
309 		break;
310 	case IEEE80211_VHT_MCS_SUPPORT_0_9:
311 		break;
312 	default:
313 		mask = 0x3ff;
314 	}
315 
316 	return 0x3ff & ~mask;
317 }
318 
319 static bool
320 minstrel_ht_is_legacy_group(int group)
321 {
322 	return group == MINSTREL_CCK_GROUP ||
323 	       group == MINSTREL_OFDM_GROUP;
324 }
325 
326 /*
327  * Look up an MCS group index based on mac80211 rate information
328  */
329 static int
330 minstrel_ht_get_group_idx(struct ieee80211_tx_rate *rate)
331 {
332 	return GROUP_IDX((rate->idx / 8) + 1,
333 			 !!(rate->flags & IEEE80211_TX_RC_SHORT_GI),
334 			 !!(rate->flags & IEEE80211_TX_RC_40_MHZ_WIDTH));
335 }
336 
337 /*
338  * Look up an MCS group index based on new cfg80211 rate_info.
339  */
340 static int
341 minstrel_ht_ri_get_group_idx(struct rate_info *rate)
342 {
343 	return GROUP_IDX((rate->mcs / 8) + 1,
344 			 !!(rate->flags & RATE_INFO_FLAGS_SHORT_GI),
345 			 !!(rate->bw & RATE_INFO_BW_40));
346 }
347 
348 static int
349 minstrel_vht_get_group_idx(struct ieee80211_tx_rate *rate)
350 {
351 	return VHT_GROUP_IDX(ieee80211_rate_get_vht_nss(rate),
352 			     !!(rate->flags & IEEE80211_TX_RC_SHORT_GI),
353 			     !!(rate->flags & IEEE80211_TX_RC_40_MHZ_WIDTH) +
354 			     2*!!(rate->flags & IEEE80211_TX_RC_80_MHZ_WIDTH));
355 }
356 
357 /*
358  * Look up an MCS group index based on new cfg80211 rate_info.
359  */
360 static int
361 minstrel_vht_ri_get_group_idx(struct rate_info *rate)
362 {
363 	return VHT_GROUP_IDX(rate->nss,
364 			     !!(rate->flags & RATE_INFO_FLAGS_SHORT_GI),
365 			     !!(rate->bw & RATE_INFO_BW_40) +
366 			     2*!!(rate->bw & RATE_INFO_BW_80));
367 }
368 
369 static struct minstrel_rate_stats *
370 minstrel_ht_get_stats(struct minstrel_priv *mp, struct minstrel_ht_sta *mi,
371 		      struct ieee80211_tx_rate *rate)
372 {
373 	int group, idx;
374 
375 	if (rate->flags & IEEE80211_TX_RC_MCS) {
376 		group = minstrel_ht_get_group_idx(rate);
377 		idx = rate->idx % 8;
378 		goto out;
379 	}
380 
381 	if (rate->flags & IEEE80211_TX_RC_VHT_MCS) {
382 		group = minstrel_vht_get_group_idx(rate);
383 		idx = ieee80211_rate_get_vht_mcs(rate);
384 		goto out;
385 	}
386 
387 	group = MINSTREL_CCK_GROUP;
388 	for (idx = 0; idx < ARRAY_SIZE(mp->cck_rates); idx++) {
389 		if (!(mi->supported[group] & BIT(idx)))
390 			continue;
391 
392 		if (rate->idx != mp->cck_rates[idx])
393 			continue;
394 
395 		/* short preamble */
396 		if ((mi->supported[group] & BIT(idx + 4)) &&
397 		    (rate->flags & IEEE80211_TX_RC_USE_SHORT_PREAMBLE))
398 			idx += 4;
399 		goto out;
400 	}
401 
402 	group = MINSTREL_OFDM_GROUP;
403 	for (idx = 0; idx < ARRAY_SIZE(mp->ofdm_rates[0]); idx++)
404 		if (rate->idx == mp->ofdm_rates[mi->band][idx])
405 			goto out;
406 
407 	idx = 0;
408 out:
409 	return &mi->groups[group].rates[idx];
410 }
411 
412 /*
413  * Get the minstrel rate statistics for specified STA and rate info.
414  */
415 static struct minstrel_rate_stats *
416 minstrel_ht_ri_get_stats(struct minstrel_priv *mp, struct minstrel_ht_sta *mi,
417 			  struct ieee80211_rate_status *rate_status)
418 {
419 	int group, idx;
420 	struct rate_info *rate = &rate_status->rate_idx;
421 
422 	if (rate->flags & RATE_INFO_FLAGS_MCS) {
423 		group = minstrel_ht_ri_get_group_idx(rate);
424 		idx = rate->mcs % 8;
425 		goto out;
426 	}
427 
428 	if (rate->flags & RATE_INFO_FLAGS_VHT_MCS) {
429 		group = minstrel_vht_ri_get_group_idx(rate);
430 		idx = rate->mcs;
431 		goto out;
432 	}
433 
434 	group = MINSTREL_CCK_GROUP;
435 	for (idx = 0; idx < ARRAY_SIZE(mp->cck_rates); idx++) {
436 		if (rate->legacy != minstrel_cck_bitrates[ mp->cck_rates[idx] ])
437 			continue;
438 
439 		/* short preamble */
440 		if ((mi->supported[group] & BIT(idx + 4)) &&
441 							mi->use_short_preamble)
442 			idx += 4;
443 		goto out;
444 	}
445 
446 	group = MINSTREL_OFDM_GROUP;
447 	for (idx = 0; idx < ARRAY_SIZE(mp->ofdm_rates[0]); idx++)
448 		if (rate->legacy == minstrel_ofdm_bitrates[ mp->ofdm_rates[mi->band][idx] ])
449 			goto out;
450 
451 	idx = 0;
452 out:
453 	return &mi->groups[group].rates[idx];
454 }
455 
456 static inline struct minstrel_rate_stats *
457 minstrel_get_ratestats(struct minstrel_ht_sta *mi, int index)
458 {
459 	return &mi->groups[MI_RATE_GROUP(index)].rates[MI_RATE_IDX(index)];
460 }
461 
462 static inline int minstrel_get_duration(int index)
463 {
464 	const struct mcs_group *group = &minstrel_mcs_groups[MI_RATE_GROUP(index)];
465 	unsigned int duration = group->duration[MI_RATE_IDX(index)];
466 
467 	return duration << group->shift;
468 }
469 
470 static unsigned int
471 minstrel_ht_avg_ampdu_len(struct minstrel_ht_sta *mi)
472 {
473 	int duration;
474 
475 	if (mi->avg_ampdu_len)
476 		return MINSTREL_TRUNC(mi->avg_ampdu_len);
477 
478 	if (minstrel_ht_is_legacy_group(MI_RATE_GROUP(mi->max_tp_rate[0])))
479 		return 1;
480 
481 	duration = minstrel_get_duration(mi->max_tp_rate[0]);
482 
483 	if (duration > 400 * 1000)
484 		return 2;
485 
486 	if (duration > 250 * 1000)
487 		return 4;
488 
489 	if (duration > 150 * 1000)
490 		return 8;
491 
492 	return 16;
493 }
494 
495 /*
496  * Return current throughput based on the average A-MPDU length, taking into
497  * account the expected number of retransmissions and their expected length
498  */
499 int
500 minstrel_ht_get_tp_avg(struct minstrel_ht_sta *mi, int group, int rate,
501 		       int prob_avg)
502 {
503 	unsigned int nsecs = 0, overhead = mi->overhead;
504 	unsigned int ampdu_len = 1;
505 
506 	/* do not account throughput if success prob is below 10% */
507 	if (prob_avg < MINSTREL_FRAC(10, 100))
508 		return 0;
509 
510 	if (minstrel_ht_is_legacy_group(group))
511 		overhead = mi->overhead_legacy;
512 	else
513 		ampdu_len = minstrel_ht_avg_ampdu_len(mi);
514 
515 	nsecs = 1000 * overhead / ampdu_len;
516 	nsecs += minstrel_mcs_groups[group].duration[rate] <<
517 		 minstrel_mcs_groups[group].shift;
518 
519 	/*
520 	 * For the throughput calculation, limit the probability value to 90% to
521 	 * account for collision related packet error rate fluctuation
522 	 * (prob is scaled - see MINSTREL_FRAC above)
523 	 */
524 	if (prob_avg > MINSTREL_FRAC(90, 100))
525 		prob_avg = MINSTREL_FRAC(90, 100);
526 
527 	return MINSTREL_TRUNC(100 * ((prob_avg * 1000000) / nsecs));
528 }
529 
530 /*
531  * Find & sort topmost throughput rates
532  *
533  * If multiple rates provide equal throughput the sorting is based on their
534  * current success probability. Higher success probability is preferred among
535  * MCS groups, CCK rates do not provide aggregation and are therefore at last.
536  */
537 static void
538 minstrel_ht_sort_best_tp_rates(struct minstrel_ht_sta *mi, u16 index,
539 			       u16 *tp_list)
540 {
541 	int cur_group, cur_idx, cur_tp_avg, cur_prob;
542 	int tmp_group, tmp_idx, tmp_tp_avg, tmp_prob;
543 	int j = MAX_THR_RATES;
544 
545 	cur_group = MI_RATE_GROUP(index);
546 	cur_idx = MI_RATE_IDX(index);
547 	cur_prob = mi->groups[cur_group].rates[cur_idx].prob_avg;
548 	cur_tp_avg = minstrel_ht_get_tp_avg(mi, cur_group, cur_idx, cur_prob);
549 
550 	do {
551 		tmp_group = MI_RATE_GROUP(tp_list[j - 1]);
552 		tmp_idx = MI_RATE_IDX(tp_list[j - 1]);
553 		tmp_prob = mi->groups[tmp_group].rates[tmp_idx].prob_avg;
554 		tmp_tp_avg = minstrel_ht_get_tp_avg(mi, tmp_group, tmp_idx,
555 						    tmp_prob);
556 		if (cur_tp_avg < tmp_tp_avg ||
557 		    (cur_tp_avg == tmp_tp_avg && cur_prob <= tmp_prob))
558 			break;
559 		j--;
560 	} while (j > 0);
561 
562 	if (j < MAX_THR_RATES - 1) {
563 		memmove(&tp_list[j + 1], &tp_list[j], (sizeof(*tp_list) *
564 		       (MAX_THR_RATES - (j + 1))));
565 	}
566 	if (j < MAX_THR_RATES)
567 		tp_list[j] = index;
568 }
569 
570 /*
571  * Find and set the topmost probability rate per sta and per group
572  */
573 static void
574 minstrel_ht_set_best_prob_rate(struct minstrel_ht_sta *mi, u16 *dest, u16 index)
575 {
576 	struct minstrel_mcs_group_data *mg;
577 	struct minstrel_rate_stats *mrs;
578 	int tmp_group, tmp_idx, tmp_tp_avg, tmp_prob;
579 	int max_tp_group, max_tp_idx, max_tp_prob;
580 	int cur_tp_avg, cur_group, cur_idx;
581 	int max_gpr_group, max_gpr_idx;
582 	int max_gpr_tp_avg, max_gpr_prob;
583 
584 	cur_group = MI_RATE_GROUP(index);
585 	cur_idx = MI_RATE_IDX(index);
586 	mg = &mi->groups[cur_group];
587 	mrs = &mg->rates[cur_idx];
588 
589 	tmp_group = MI_RATE_GROUP(*dest);
590 	tmp_idx = MI_RATE_IDX(*dest);
591 	tmp_prob = mi->groups[tmp_group].rates[tmp_idx].prob_avg;
592 	tmp_tp_avg = minstrel_ht_get_tp_avg(mi, tmp_group, tmp_idx, tmp_prob);
593 
594 	/* if max_tp_rate[0] is from MCS_GROUP max_prob_rate get selected from
595 	 * MCS_GROUP as well as CCK_GROUP rates do not allow aggregation */
596 	max_tp_group = MI_RATE_GROUP(mi->max_tp_rate[0]);
597 	max_tp_idx = MI_RATE_IDX(mi->max_tp_rate[0]);
598 	max_tp_prob = mi->groups[max_tp_group].rates[max_tp_idx].prob_avg;
599 
600 	if (minstrel_ht_is_legacy_group(MI_RATE_GROUP(index)) &&
601 	    !minstrel_ht_is_legacy_group(max_tp_group))
602 		return;
603 
604 	/* skip rates faster than max tp rate with lower prob */
605 	if (minstrel_get_duration(mi->max_tp_rate[0]) > minstrel_get_duration(index) &&
606 	    mrs->prob_avg < max_tp_prob)
607 		return;
608 
609 	max_gpr_group = MI_RATE_GROUP(mg->max_group_prob_rate);
610 	max_gpr_idx = MI_RATE_IDX(mg->max_group_prob_rate);
611 	max_gpr_prob = mi->groups[max_gpr_group].rates[max_gpr_idx].prob_avg;
612 
613 	if (mrs->prob_avg > MINSTREL_FRAC(75, 100)) {
614 		cur_tp_avg = minstrel_ht_get_tp_avg(mi, cur_group, cur_idx,
615 						    mrs->prob_avg);
616 		if (cur_tp_avg > tmp_tp_avg)
617 			*dest = index;
618 
619 		max_gpr_tp_avg = minstrel_ht_get_tp_avg(mi, max_gpr_group,
620 							max_gpr_idx,
621 							max_gpr_prob);
622 		if (cur_tp_avg > max_gpr_tp_avg)
623 			mg->max_group_prob_rate = index;
624 	} else {
625 		if (mrs->prob_avg > tmp_prob)
626 			*dest = index;
627 		if (mrs->prob_avg > max_gpr_prob)
628 			mg->max_group_prob_rate = index;
629 	}
630 }
631 
632 
633 /*
634  * Assign new rate set per sta and use CCK rates only if the fastest
635  * rate (max_tp_rate[0]) is from CCK group. This prohibits such sorted
636  * rate sets where MCS and CCK rates are mixed, because CCK rates can
637  * not use aggregation.
638  */
639 static void
640 minstrel_ht_assign_best_tp_rates(struct minstrel_ht_sta *mi,
641 				 u16 tmp_mcs_tp_rate[MAX_THR_RATES],
642 				 u16 tmp_legacy_tp_rate[MAX_THR_RATES])
643 {
644 	unsigned int tmp_group, tmp_idx, tmp_cck_tp, tmp_mcs_tp, tmp_prob;
645 	int i;
646 
647 	tmp_group = MI_RATE_GROUP(tmp_legacy_tp_rate[0]);
648 	tmp_idx = MI_RATE_IDX(tmp_legacy_tp_rate[0]);
649 	tmp_prob = mi->groups[tmp_group].rates[tmp_idx].prob_avg;
650 	tmp_cck_tp = minstrel_ht_get_tp_avg(mi, tmp_group, tmp_idx, tmp_prob);
651 
652 	tmp_group = MI_RATE_GROUP(tmp_mcs_tp_rate[0]);
653 	tmp_idx = MI_RATE_IDX(tmp_mcs_tp_rate[0]);
654 	tmp_prob = mi->groups[tmp_group].rates[tmp_idx].prob_avg;
655 	tmp_mcs_tp = minstrel_ht_get_tp_avg(mi, tmp_group, tmp_idx, tmp_prob);
656 
657 	if (tmp_cck_tp > tmp_mcs_tp) {
658 		for(i = 0; i < MAX_THR_RATES; i++) {
659 			minstrel_ht_sort_best_tp_rates(mi, tmp_legacy_tp_rate[i],
660 						       tmp_mcs_tp_rate);
661 		}
662 	}
663 
664 }
665 
666 /*
667  * Try to increase robustness of max_prob rate by decrease number of
668  * streams if possible.
669  */
670 static inline void
671 minstrel_ht_prob_rate_reduce_streams(struct minstrel_ht_sta *mi)
672 {
673 	struct minstrel_mcs_group_data *mg;
674 	int tmp_max_streams, group, tmp_idx, tmp_prob;
675 	int tmp_tp = 0;
676 
677 	if (!mi->sta->deflink.ht_cap.ht_supported)
678 		return;
679 
680 	group = MI_RATE_GROUP(mi->max_tp_rate[0]);
681 	tmp_max_streams = minstrel_mcs_groups[group].streams;
682 	for (group = 0; group < ARRAY_SIZE(minstrel_mcs_groups); group++) {
683 		mg = &mi->groups[group];
684 		if (!mi->supported[group] || group == MINSTREL_CCK_GROUP)
685 			continue;
686 
687 		tmp_idx = MI_RATE_IDX(mg->max_group_prob_rate);
688 		tmp_prob = mi->groups[group].rates[tmp_idx].prob_avg;
689 
690 		if (tmp_tp < minstrel_ht_get_tp_avg(mi, group, tmp_idx, tmp_prob) &&
691 		   (minstrel_mcs_groups[group].streams < tmp_max_streams)) {
692 				mi->max_prob_rate = mg->max_group_prob_rate;
693 				tmp_tp = minstrel_ht_get_tp_avg(mi, group,
694 								tmp_idx,
695 								tmp_prob);
696 		}
697 	}
698 }
699 
700 static u16
701 __minstrel_ht_get_sample_rate(struct minstrel_ht_sta *mi,
702 			      enum minstrel_sample_type type)
703 {
704 	u16 *rates = mi->sample[type].sample_rates;
705 	u16 cur;
706 	int i;
707 
708 	for (i = 0; i < MINSTREL_SAMPLE_RATES; i++) {
709 		if (!rates[i])
710 			continue;
711 
712 		cur = rates[i];
713 		rates[i] = 0;
714 		return cur;
715 	}
716 
717 	return 0;
718 }
719 
720 static inline int
721 minstrel_ewma(int old, int new, int weight)
722 {
723 	int diff, incr;
724 
725 	diff = new - old;
726 	incr = (EWMA_DIV - weight) * diff / EWMA_DIV;
727 
728 	return old + incr;
729 }
730 
731 static inline int minstrel_filter_avg_add(u16 *prev_1, u16 *prev_2, s32 in)
732 {
733 	s32 out_1 = *prev_1;
734 	s32 out_2 = *prev_2;
735 	s32 val;
736 
737 	if (!in)
738 		in += 1;
739 
740 	if (!out_1) {
741 		val = out_1 = in;
742 		goto out;
743 	}
744 
745 	val = MINSTREL_AVG_COEFF1 * in;
746 	val += MINSTREL_AVG_COEFF2 * out_1;
747 	val += MINSTREL_AVG_COEFF3 * out_2;
748 	val >>= MINSTREL_SCALE;
749 
750 	if (val > 1 << MINSTREL_SCALE)
751 		val = 1 << MINSTREL_SCALE;
752 	if (val < 0)
753 		val = 1;
754 
755 out:
756 	*prev_2 = out_1;
757 	*prev_1 = val;
758 
759 	return val;
760 }
761 
762 /*
763 * Recalculate statistics and counters of a given rate
764 */
765 static void
766 minstrel_ht_calc_rate_stats(struct minstrel_priv *mp,
767 			    struct minstrel_rate_stats *mrs)
768 {
769 	unsigned int cur_prob;
770 
771 	if (unlikely(mrs->attempts > 0)) {
772 		cur_prob = MINSTREL_FRAC(mrs->success, mrs->attempts);
773 		minstrel_filter_avg_add(&mrs->prob_avg,
774 					&mrs->prob_avg_1, cur_prob);
775 		mrs->att_hist += mrs->attempts;
776 		mrs->succ_hist += mrs->success;
777 	}
778 
779 	mrs->last_success = mrs->success;
780 	mrs->last_attempts = mrs->attempts;
781 	mrs->success = 0;
782 	mrs->attempts = 0;
783 }
784 
785 static bool
786 minstrel_ht_find_sample_rate(struct minstrel_ht_sta *mi, int type, int idx)
787 {
788 	int i;
789 
790 	for (i = 0; i < MINSTREL_SAMPLE_RATES; i++) {
791 		u16 cur = mi->sample[type].sample_rates[i];
792 
793 		if (cur == idx)
794 			return true;
795 
796 		if (!cur)
797 			break;
798 	}
799 
800 	return false;
801 }
802 
803 static int
804 minstrel_ht_move_sample_rates(struct minstrel_ht_sta *mi, int type,
805 			      u32 fast_rate_dur, u32 slow_rate_dur)
806 {
807 	u16 *rates = mi->sample[type].sample_rates;
808 	int i, j;
809 
810 	for (i = 0, j = 0; i < MINSTREL_SAMPLE_RATES; i++) {
811 		u32 duration;
812 		bool valid = false;
813 		u16 cur;
814 
815 		cur = rates[i];
816 		if (!cur)
817 			continue;
818 
819 		duration = minstrel_get_duration(cur);
820 		switch (type) {
821 		case MINSTREL_SAMPLE_TYPE_SLOW:
822 			valid = duration > fast_rate_dur &&
823 				duration < slow_rate_dur;
824 			break;
825 		case MINSTREL_SAMPLE_TYPE_INC:
826 		case MINSTREL_SAMPLE_TYPE_JUMP:
827 			valid = duration < fast_rate_dur;
828 			break;
829 		default:
830 			valid = false;
831 			break;
832 		}
833 
834 		if (!valid) {
835 			rates[i] = 0;
836 			continue;
837 		}
838 
839 		if (i == j)
840 			continue;
841 
842 		rates[j++] = cur;
843 		rates[i] = 0;
844 	}
845 
846 	return j;
847 }
848 
849 static int
850 minstrel_ht_group_min_rate_offset(struct minstrel_ht_sta *mi, int group,
851 				  u32 max_duration)
852 {
853 	u16 supported = mi->supported[group];
854 	int i;
855 
856 	for (i = 0; i < MCS_GROUP_RATES && supported; i++, supported >>= 1) {
857 		if (!(supported & BIT(0)))
858 			continue;
859 
860 		if (minstrel_get_duration(MI_RATE(group, i)) >= max_duration)
861 			continue;
862 
863 		return i;
864 	}
865 
866 	return -1;
867 }
868 
869 /*
870  * Incremental update rates:
871  * Flip through groups and pick the first group rate that is faster than the
872  * highest currently selected rate
873  */
874 static u16
875 minstrel_ht_next_inc_rate(struct minstrel_ht_sta *mi, u32 fast_rate_dur)
876 {
877 	u8 type = MINSTREL_SAMPLE_TYPE_INC;
878 	int i, index = 0;
879 	u8 group;
880 
881 	group = mi->sample[type].sample_group;
882 	for (i = 0; i < ARRAY_SIZE(minstrel_mcs_groups); i++) {
883 		group = (group + 1) % ARRAY_SIZE(minstrel_mcs_groups);
884 
885 		index = minstrel_ht_group_min_rate_offset(mi, group,
886 							  fast_rate_dur);
887 		if (index < 0)
888 			continue;
889 
890 		index = MI_RATE(group, index & 0xf);
891 		if (!minstrel_ht_find_sample_rate(mi, type, index))
892 			goto out;
893 	}
894 	index = 0;
895 
896 out:
897 	mi->sample[type].sample_group = group;
898 
899 	return index;
900 }
901 
902 static int
903 minstrel_ht_next_group_sample_rate(struct minstrel_ht_sta *mi, int group,
904 				   u16 supported, int offset)
905 {
906 	struct minstrel_mcs_group_data *mg = &mi->groups[group];
907 	u16 idx;
908 	int i;
909 
910 	for (i = 0; i < MCS_GROUP_RATES; i++) {
911 		idx = sample_table[mg->column][mg->index];
912 		if (++mg->index >= MCS_GROUP_RATES) {
913 			mg->index = 0;
914 			if (++mg->column >= ARRAY_SIZE(sample_table))
915 				mg->column = 0;
916 		}
917 
918 		if (idx < offset)
919 			continue;
920 
921 		if (!(supported & BIT(idx)))
922 			continue;
923 
924 		return MI_RATE(group, idx);
925 	}
926 
927 	return -1;
928 }
929 
930 /*
931  * Jump rates:
932  * Sample random rates, use those that are faster than the highest
933  * currently selected rate. Rates between the fastest and the slowest
934  * get sorted into the slow sample bucket, but only if it has room
935  */
936 static u16
937 minstrel_ht_next_jump_rate(struct minstrel_ht_sta *mi, u32 fast_rate_dur,
938 			   u32 slow_rate_dur, int *slow_rate_ofs)
939 {
940 	struct minstrel_rate_stats *mrs;
941 	u32 max_duration = slow_rate_dur;
942 	int i, index, offset;
943 	u16 *slow_rates;
944 	u16 supported;
945 	u32 duration;
946 	u8 group;
947 
948 	if (*slow_rate_ofs >= MINSTREL_SAMPLE_RATES)
949 		max_duration = fast_rate_dur;
950 
951 	slow_rates = mi->sample[MINSTREL_SAMPLE_TYPE_SLOW].sample_rates;
952 	group = mi->sample[MINSTREL_SAMPLE_TYPE_JUMP].sample_group;
953 	for (i = 0; i < ARRAY_SIZE(minstrel_mcs_groups); i++) {
954 		u8 type;
955 
956 		group = (group + 1) % ARRAY_SIZE(minstrel_mcs_groups);
957 
958 		supported = mi->supported[group];
959 		if (!supported)
960 			continue;
961 
962 		offset = minstrel_ht_group_min_rate_offset(mi, group,
963 							   max_duration);
964 		if (offset < 0)
965 			continue;
966 
967 		index = minstrel_ht_next_group_sample_rate(mi, group, supported,
968 							   offset);
969 		if (index < 0)
970 			continue;
971 
972 		duration = minstrel_get_duration(index);
973 		if (duration < fast_rate_dur)
974 			type = MINSTREL_SAMPLE_TYPE_JUMP;
975 		else
976 			type = MINSTREL_SAMPLE_TYPE_SLOW;
977 
978 		if (minstrel_ht_find_sample_rate(mi, type, index))
979 			continue;
980 
981 		if (type == MINSTREL_SAMPLE_TYPE_JUMP)
982 			goto found;
983 
984 		if (*slow_rate_ofs >= MINSTREL_SAMPLE_RATES)
985 			continue;
986 
987 		if (duration >= slow_rate_dur)
988 			continue;
989 
990 		/* skip slow rates with high success probability */
991 		mrs = minstrel_get_ratestats(mi, index);
992 		if (mrs->prob_avg > MINSTREL_FRAC(95, 100))
993 			continue;
994 
995 		slow_rates[(*slow_rate_ofs)++] = index;
996 		if (*slow_rate_ofs >= MINSTREL_SAMPLE_RATES)
997 			max_duration = fast_rate_dur;
998 	}
999 	index = 0;
1000 
1001 found:
1002 	mi->sample[MINSTREL_SAMPLE_TYPE_JUMP].sample_group = group;
1003 
1004 	return index;
1005 }
1006 
1007 static void
1008 minstrel_ht_refill_sample_rates(struct minstrel_ht_sta *mi)
1009 {
1010 	u32 prob_dur = minstrel_get_duration(mi->max_prob_rate);
1011 	u32 tp_dur = minstrel_get_duration(mi->max_tp_rate[0]);
1012 	u32 tp2_dur = minstrel_get_duration(mi->max_tp_rate[1]);
1013 	u32 fast_rate_dur = min(min(tp_dur, tp2_dur), prob_dur);
1014 	u32 slow_rate_dur = max(max(tp_dur, tp2_dur), prob_dur);
1015 	u16 *rates;
1016 	int i, j;
1017 
1018 	rates = mi->sample[MINSTREL_SAMPLE_TYPE_INC].sample_rates;
1019 	i = minstrel_ht_move_sample_rates(mi, MINSTREL_SAMPLE_TYPE_INC,
1020 					  fast_rate_dur, slow_rate_dur);
1021 	while (i < MINSTREL_SAMPLE_RATES) {
1022 		rates[i] = minstrel_ht_next_inc_rate(mi, tp_dur);
1023 		if (!rates[i])
1024 			break;
1025 
1026 		i++;
1027 	}
1028 
1029 	rates = mi->sample[MINSTREL_SAMPLE_TYPE_JUMP].sample_rates;
1030 	i = minstrel_ht_move_sample_rates(mi, MINSTREL_SAMPLE_TYPE_JUMP,
1031 					  fast_rate_dur, slow_rate_dur);
1032 	j = minstrel_ht_move_sample_rates(mi, MINSTREL_SAMPLE_TYPE_SLOW,
1033 					  fast_rate_dur, slow_rate_dur);
1034 	while (i < MINSTREL_SAMPLE_RATES) {
1035 		rates[i] = minstrel_ht_next_jump_rate(mi, fast_rate_dur,
1036 						      slow_rate_dur, &j);
1037 		if (!rates[i])
1038 			break;
1039 
1040 		i++;
1041 	}
1042 
1043 	for (i = 0; i < ARRAY_SIZE(mi->sample); i++)
1044 		memcpy(mi->sample[i].cur_sample_rates, mi->sample[i].sample_rates,
1045 		       sizeof(mi->sample[i].cur_sample_rates));
1046 }
1047 
1048 
1049 /*
1050  * Update rate statistics and select new primary rates
1051  *
1052  * Rules for rate selection:
1053  *  - max_prob_rate must use only one stream, as a tradeoff between delivery
1054  *    probability and throughput during strong fluctuations
1055  *  - as long as the max prob rate has a probability of more than 75%, pick
1056  *    higher throughput rates, even if the probablity is a bit lower
1057  */
1058 static void
1059 minstrel_ht_update_stats(struct minstrel_priv *mp, struct minstrel_ht_sta *mi)
1060 {
1061 	struct minstrel_mcs_group_data *mg;
1062 	struct minstrel_rate_stats *mrs;
1063 	int group, i, j, cur_prob;
1064 	u16 tmp_mcs_tp_rate[MAX_THR_RATES], tmp_group_tp_rate[MAX_THR_RATES];
1065 	u16 tmp_legacy_tp_rate[MAX_THR_RATES], tmp_max_prob_rate;
1066 	u16 index;
1067 	bool ht_supported = mi->sta->deflink.ht_cap.ht_supported;
1068 
1069 	if (mi->ampdu_packets > 0) {
1070 		if (!ieee80211_hw_check(mp->hw, TX_STATUS_NO_AMPDU_LEN))
1071 			mi->avg_ampdu_len = minstrel_ewma(mi->avg_ampdu_len,
1072 				MINSTREL_FRAC(mi->ampdu_len, mi->ampdu_packets),
1073 					      EWMA_LEVEL);
1074 		else
1075 			mi->avg_ampdu_len = 0;
1076 		mi->ampdu_len = 0;
1077 		mi->ampdu_packets = 0;
1078 	}
1079 
1080 	if (mi->supported[MINSTREL_CCK_GROUP])
1081 		group = MINSTREL_CCK_GROUP;
1082 	else if (mi->supported[MINSTREL_OFDM_GROUP])
1083 		group = MINSTREL_OFDM_GROUP;
1084 	else
1085 		group = 0;
1086 
1087 	index = MI_RATE(group, 0);
1088 	for (j = 0; j < ARRAY_SIZE(tmp_legacy_tp_rate); j++)
1089 		tmp_legacy_tp_rate[j] = index;
1090 
1091 	if (mi->supported[MINSTREL_VHT_GROUP_0])
1092 		group = MINSTREL_VHT_GROUP_0;
1093 	else if (ht_supported)
1094 		group = MINSTREL_HT_GROUP_0;
1095 	else if (mi->supported[MINSTREL_CCK_GROUP])
1096 		group = MINSTREL_CCK_GROUP;
1097 	else
1098 		group = MINSTREL_OFDM_GROUP;
1099 
1100 	index = MI_RATE(group, 0);
1101 	tmp_max_prob_rate = index;
1102 	for (j = 0; j < ARRAY_SIZE(tmp_mcs_tp_rate); j++)
1103 		tmp_mcs_tp_rate[j] = index;
1104 
1105 	/* Find best rate sets within all MCS groups*/
1106 	for (group = 0; group < ARRAY_SIZE(minstrel_mcs_groups); group++) {
1107 		u16 *tp_rate = tmp_mcs_tp_rate;
1108 		u16 last_prob = 0;
1109 
1110 		mg = &mi->groups[group];
1111 		if (!mi->supported[group])
1112 			continue;
1113 
1114 		/* (re)Initialize group rate indexes */
1115 		for(j = 0; j < MAX_THR_RATES; j++)
1116 			tmp_group_tp_rate[j] = MI_RATE(group, 0);
1117 
1118 		if (group == MINSTREL_CCK_GROUP && ht_supported)
1119 			tp_rate = tmp_legacy_tp_rate;
1120 
1121 		for (i = MCS_GROUP_RATES - 1; i >= 0; i--) {
1122 			if (!(mi->supported[group] & BIT(i)))
1123 				continue;
1124 
1125 			index = MI_RATE(group, i);
1126 
1127 			mrs = &mg->rates[i];
1128 			mrs->retry_updated = false;
1129 			minstrel_ht_calc_rate_stats(mp, mrs);
1130 
1131 			if (mrs->att_hist)
1132 				last_prob = max(last_prob, mrs->prob_avg);
1133 			else
1134 				mrs->prob_avg = max(last_prob, mrs->prob_avg);
1135 			cur_prob = mrs->prob_avg;
1136 
1137 			if (minstrel_ht_get_tp_avg(mi, group, i, cur_prob) == 0)
1138 				continue;
1139 
1140 			/* Find max throughput rate set */
1141 			minstrel_ht_sort_best_tp_rates(mi, index, tp_rate);
1142 
1143 			/* Find max throughput rate set within a group */
1144 			minstrel_ht_sort_best_tp_rates(mi, index,
1145 						       tmp_group_tp_rate);
1146 		}
1147 
1148 		memcpy(mg->max_group_tp_rate, tmp_group_tp_rate,
1149 		       sizeof(mg->max_group_tp_rate));
1150 	}
1151 
1152 	/* Assign new rate set per sta */
1153 	minstrel_ht_assign_best_tp_rates(mi, tmp_mcs_tp_rate,
1154 					 tmp_legacy_tp_rate);
1155 	memcpy(mi->max_tp_rate, tmp_mcs_tp_rate, sizeof(mi->max_tp_rate));
1156 
1157 	for (group = 0; group < ARRAY_SIZE(minstrel_mcs_groups); group++) {
1158 		if (!mi->supported[group])
1159 			continue;
1160 
1161 		mg = &mi->groups[group];
1162 		mg->max_group_prob_rate = MI_RATE(group, 0);
1163 
1164 		for (i = 0; i < MCS_GROUP_RATES; i++) {
1165 			if (!(mi->supported[group] & BIT(i)))
1166 				continue;
1167 
1168 			index = MI_RATE(group, i);
1169 
1170 			/* Find max probability rate per group and global */
1171 			minstrel_ht_set_best_prob_rate(mi, &tmp_max_prob_rate,
1172 						       index);
1173 		}
1174 	}
1175 
1176 	mi->max_prob_rate = tmp_max_prob_rate;
1177 
1178 	/* Try to increase robustness of max_prob_rate*/
1179 	minstrel_ht_prob_rate_reduce_streams(mi);
1180 	minstrel_ht_refill_sample_rates(mi);
1181 
1182 #ifdef CONFIG_MAC80211_DEBUGFS
1183 	/* use fixed index if set */
1184 	if (mp->fixed_rate_idx != -1) {
1185 		for (i = 0; i < 4; i++)
1186 			mi->max_tp_rate[i] = mp->fixed_rate_idx;
1187 		mi->max_prob_rate = mp->fixed_rate_idx;
1188 	}
1189 #endif
1190 
1191 	/* Reset update timer */
1192 	mi->last_stats_update = jiffies;
1193 	mi->sample_time = jiffies;
1194 }
1195 
1196 static bool
1197 minstrel_ht_txstat_valid(struct minstrel_priv *mp, struct minstrel_ht_sta *mi,
1198 			 struct ieee80211_tx_rate *rate)
1199 {
1200 	int i;
1201 
1202 	if (rate->idx < 0)
1203 		return false;
1204 
1205 	if (!rate->count)
1206 		return false;
1207 
1208 	if (rate->flags & IEEE80211_TX_RC_MCS ||
1209 	    rate->flags & IEEE80211_TX_RC_VHT_MCS)
1210 		return true;
1211 
1212 	for (i = 0; i < ARRAY_SIZE(mp->cck_rates); i++)
1213 		if (rate->idx == mp->cck_rates[i])
1214 			return true;
1215 
1216 	for (i = 0; i < ARRAY_SIZE(mp->ofdm_rates[0]); i++)
1217 		if (rate->idx == mp->ofdm_rates[mi->band][i])
1218 			return true;
1219 
1220 	return false;
1221 }
1222 
1223 /*
1224  * Check whether rate_status contains valid information.
1225  */
1226 static bool
1227 minstrel_ht_ri_txstat_valid(struct minstrel_priv *mp,
1228 			    struct minstrel_ht_sta *mi,
1229 			    struct ieee80211_rate_status *rate_status)
1230 {
1231 	int i;
1232 
1233 	if (!rate_status)
1234 		return false;
1235 	if (!rate_status->try_count)
1236 		return false;
1237 
1238 	if (rate_status->rate_idx.flags & RATE_INFO_FLAGS_MCS ||
1239 	    rate_status->rate_idx.flags & RATE_INFO_FLAGS_VHT_MCS)
1240 		return true;
1241 
1242 	for (i = 0; i < ARRAY_SIZE(mp->cck_rates); i++) {
1243 		if (rate_status->rate_idx.legacy ==
1244 		    minstrel_cck_bitrates[ mp->cck_rates[i] ])
1245 			return true;
1246 	}
1247 
1248 	for (i = 0; i < ARRAY_SIZE(mp->ofdm_rates); i++) {
1249 		if (rate_status->rate_idx.legacy ==
1250 		    minstrel_ofdm_bitrates[ mp->ofdm_rates[mi->band][i] ])
1251 			return true;
1252 	}
1253 
1254 	return false;
1255 }
1256 
1257 static void
1258 minstrel_downgrade_rate(struct minstrel_ht_sta *mi, u16 *idx, bool primary)
1259 {
1260 	int group, orig_group;
1261 
1262 	orig_group = group = MI_RATE_GROUP(*idx);
1263 	while (group > 0) {
1264 		group--;
1265 
1266 		if (!mi->supported[group])
1267 			continue;
1268 
1269 		if (minstrel_mcs_groups[group].streams >
1270 		    minstrel_mcs_groups[orig_group].streams)
1271 			continue;
1272 
1273 		if (primary)
1274 			*idx = mi->groups[group].max_group_tp_rate[0];
1275 		else
1276 			*idx = mi->groups[group].max_group_tp_rate[1];
1277 		break;
1278 	}
1279 }
1280 
1281 static void
1282 minstrel_ht_tx_status(void *priv, struct ieee80211_supported_band *sband,
1283                       void *priv_sta, struct ieee80211_tx_status *st)
1284 {
1285 	struct ieee80211_tx_info *info = st->info;
1286 	struct minstrel_ht_sta *mi = priv_sta;
1287 	struct ieee80211_tx_rate *ar = info->status.rates;
1288 	struct minstrel_rate_stats *rate, *rate2;
1289 	struct minstrel_priv *mp = priv;
1290 	u32 update_interval = mp->update_interval;
1291 	bool last, update = false;
1292 	int i;
1293 
1294 	/* Ignore packet that was sent with noAck flag */
1295 	if (info->flags & IEEE80211_TX_CTL_NO_ACK)
1296 		return;
1297 
1298 	/* This packet was aggregated but doesn't carry status info */
1299 	if ((info->flags & IEEE80211_TX_CTL_AMPDU) &&
1300 	    !(info->flags & IEEE80211_TX_STAT_AMPDU))
1301 		return;
1302 
1303 	if (!(info->flags & IEEE80211_TX_STAT_AMPDU)) {
1304 		info->status.ampdu_ack_len =
1305 			(info->flags & IEEE80211_TX_STAT_ACK ? 1 : 0);
1306 		info->status.ampdu_len = 1;
1307 	}
1308 
1309 	/* wraparound */
1310 	if (mi->total_packets >= ~0 - info->status.ampdu_len) {
1311 		mi->total_packets = 0;
1312 		mi->sample_packets = 0;
1313 	}
1314 
1315 	mi->total_packets += info->status.ampdu_len;
1316 	if (info->flags & IEEE80211_TX_CTL_RATE_CTRL_PROBE)
1317 		mi->sample_packets += info->status.ampdu_len;
1318 
1319 	mi->ampdu_packets++;
1320 	mi->ampdu_len += info->status.ampdu_len;
1321 
1322 	if (st->rates && st->n_rates) {
1323 		last = !minstrel_ht_ri_txstat_valid(mp, mi, &(st->rates[0]));
1324 		for (i = 0; !last; i++) {
1325 			last = (i == st->n_rates - 1) ||
1326 				!minstrel_ht_ri_txstat_valid(mp, mi,
1327 							&(st->rates[i + 1]));
1328 
1329 			rate = minstrel_ht_ri_get_stats(mp, mi,
1330 							&(st->rates[i]));
1331 
1332 			if (last)
1333 				rate->success += info->status.ampdu_ack_len;
1334 
1335 			rate->attempts += st->rates[i].try_count *
1336 					  info->status.ampdu_len;
1337 		}
1338 	} else {
1339 		last = !minstrel_ht_txstat_valid(mp, mi, &ar[0]);
1340 		for (i = 0; !last; i++) {
1341 			last = (i == IEEE80211_TX_MAX_RATES - 1) ||
1342 				!minstrel_ht_txstat_valid(mp, mi, &ar[i + 1]);
1343 
1344 			rate = minstrel_ht_get_stats(mp, mi, &ar[i]);
1345 			if (last)
1346 				rate->success += info->status.ampdu_ack_len;
1347 
1348 			rate->attempts += ar[i].count * info->status.ampdu_len;
1349 		}
1350 	}
1351 
1352 	if (mp->hw->max_rates > 1) {
1353 		/*
1354 		 * check for sudden death of spatial multiplexing,
1355 		 * downgrade to a lower number of streams if necessary.
1356 		 */
1357 		rate = minstrel_get_ratestats(mi, mi->max_tp_rate[0]);
1358 		if (rate->attempts > 30 &&
1359 		    rate->success < rate->attempts / 4) {
1360 			minstrel_downgrade_rate(mi, &mi->max_tp_rate[0], true);
1361 			update = true;
1362 		}
1363 
1364 		rate2 = minstrel_get_ratestats(mi, mi->max_tp_rate[1]);
1365 		if (rate2->attempts > 30 &&
1366 		    rate2->success < rate2->attempts / 4) {
1367 			minstrel_downgrade_rate(mi, &mi->max_tp_rate[1], false);
1368 			update = true;
1369 		}
1370 	}
1371 
1372 	if (time_after(jiffies, mi->last_stats_update + update_interval)) {
1373 		update = true;
1374 		minstrel_ht_update_stats(mp, mi);
1375 	}
1376 
1377 	if (update)
1378 		minstrel_ht_update_rates(mp, mi);
1379 }
1380 
1381 static void
1382 minstrel_calc_retransmit(struct minstrel_priv *mp, struct minstrel_ht_sta *mi,
1383                          int index)
1384 {
1385 	struct minstrel_rate_stats *mrs;
1386 	unsigned int tx_time, tx_time_rtscts, tx_time_data;
1387 	unsigned int cw = mp->cw_min;
1388 	unsigned int ctime = 0;
1389 	unsigned int t_slot = 9; /* FIXME */
1390 	unsigned int ampdu_len = minstrel_ht_avg_ampdu_len(mi);
1391 	unsigned int overhead = 0, overhead_rtscts = 0;
1392 
1393 	mrs = minstrel_get_ratestats(mi, index);
1394 	if (mrs->prob_avg < MINSTREL_FRAC(1, 10)) {
1395 		mrs->retry_count = 1;
1396 		mrs->retry_count_rtscts = 1;
1397 		return;
1398 	}
1399 
1400 	mrs->retry_count = 2;
1401 	mrs->retry_count_rtscts = 2;
1402 	mrs->retry_updated = true;
1403 
1404 	tx_time_data = minstrel_get_duration(index) * ampdu_len / 1000;
1405 
1406 	/* Contention time for first 2 tries */
1407 	ctime = (t_slot * cw) >> 1;
1408 	cw = min((cw << 1) | 1, mp->cw_max);
1409 	ctime += (t_slot * cw) >> 1;
1410 	cw = min((cw << 1) | 1, mp->cw_max);
1411 
1412 	if (minstrel_ht_is_legacy_group(MI_RATE_GROUP(index))) {
1413 		overhead = mi->overhead_legacy;
1414 		overhead_rtscts = mi->overhead_legacy_rtscts;
1415 	} else {
1416 		overhead = mi->overhead;
1417 		overhead_rtscts = mi->overhead_rtscts;
1418 	}
1419 
1420 	/* Total TX time for data and Contention after first 2 tries */
1421 	tx_time = ctime + 2 * (overhead + tx_time_data);
1422 	tx_time_rtscts = ctime + 2 * (overhead_rtscts + tx_time_data);
1423 
1424 	/* See how many more tries we can fit inside segment size */
1425 	do {
1426 		/* Contention time for this try */
1427 		ctime = (t_slot * cw) >> 1;
1428 		cw = min((cw << 1) | 1, mp->cw_max);
1429 
1430 		/* Total TX time after this try */
1431 		tx_time += ctime + overhead + tx_time_data;
1432 		tx_time_rtscts += ctime + overhead_rtscts + tx_time_data;
1433 
1434 		if (tx_time_rtscts < mp->segment_size)
1435 			mrs->retry_count_rtscts++;
1436 	} while ((tx_time < mp->segment_size) &&
1437 	         (++mrs->retry_count < mp->max_retry));
1438 }
1439 
1440 
1441 static void
1442 minstrel_ht_set_rate(struct minstrel_priv *mp, struct minstrel_ht_sta *mi,
1443                      struct ieee80211_sta_rates *ratetbl, int offset, int index)
1444 {
1445 	int group_idx = MI_RATE_GROUP(index);
1446 	const struct mcs_group *group = &minstrel_mcs_groups[group_idx];
1447 	struct minstrel_rate_stats *mrs;
1448 	u8 idx;
1449 	u16 flags = group->flags;
1450 
1451 	mrs = minstrel_get_ratestats(mi, index);
1452 	if (!mrs->retry_updated)
1453 		minstrel_calc_retransmit(mp, mi, index);
1454 
1455 	if (mrs->prob_avg < MINSTREL_FRAC(20, 100) || !mrs->retry_count) {
1456 		ratetbl->rate[offset].count = 2;
1457 		ratetbl->rate[offset].count_rts = 2;
1458 		ratetbl->rate[offset].count_cts = 2;
1459 	} else {
1460 		ratetbl->rate[offset].count = mrs->retry_count;
1461 		ratetbl->rate[offset].count_cts = mrs->retry_count;
1462 		ratetbl->rate[offset].count_rts = mrs->retry_count_rtscts;
1463 	}
1464 
1465 	index = MI_RATE_IDX(index);
1466 	if (group_idx == MINSTREL_CCK_GROUP)
1467 		idx = mp->cck_rates[index % ARRAY_SIZE(mp->cck_rates)];
1468 	else if (group_idx == MINSTREL_OFDM_GROUP)
1469 		idx = mp->ofdm_rates[mi->band][index %
1470 					       ARRAY_SIZE(mp->ofdm_rates[0])];
1471 	else if (flags & IEEE80211_TX_RC_VHT_MCS)
1472 		idx = ((group->streams - 1) << 4) |
1473 		      (index & 0xF);
1474 	else
1475 		idx = index + (group->streams - 1) * 8;
1476 
1477 	/* enable RTS/CTS if needed:
1478 	 *  - if station is in dynamic SMPS (and streams > 1)
1479 	 *  - for fallback rates, to increase chances of getting through
1480 	 */
1481 	if (offset > 0 ||
1482 	    (mi->sta->deflink.smps_mode == IEEE80211_SMPS_DYNAMIC &&
1483 	     group->streams > 1)) {
1484 		ratetbl->rate[offset].count = ratetbl->rate[offset].count_rts;
1485 		flags |= IEEE80211_TX_RC_USE_RTS_CTS;
1486 	}
1487 
1488 	ratetbl->rate[offset].idx = idx;
1489 	ratetbl->rate[offset].flags = flags;
1490 }
1491 
1492 static inline int
1493 minstrel_ht_get_prob_avg(struct minstrel_ht_sta *mi, int rate)
1494 {
1495 	int group = MI_RATE_GROUP(rate);
1496 	rate = MI_RATE_IDX(rate);
1497 	return mi->groups[group].rates[rate].prob_avg;
1498 }
1499 
1500 static int
1501 minstrel_ht_get_max_amsdu_len(struct minstrel_ht_sta *mi)
1502 {
1503 	int group = MI_RATE_GROUP(mi->max_prob_rate);
1504 	const struct mcs_group *g = &minstrel_mcs_groups[group];
1505 	int rate = MI_RATE_IDX(mi->max_prob_rate);
1506 	unsigned int duration;
1507 
1508 	/* Disable A-MSDU if max_prob_rate is bad */
1509 	if (mi->groups[group].rates[rate].prob_avg < MINSTREL_FRAC(50, 100))
1510 		return 1;
1511 
1512 	duration = g->duration[rate];
1513 	duration <<= g->shift;
1514 
1515 	/* If the rate is slower than single-stream MCS1, make A-MSDU limit small */
1516 	if (duration > MCS_DURATION(1, 0, 52))
1517 		return 500;
1518 
1519 	/*
1520 	 * If the rate is slower than single-stream MCS4, limit A-MSDU to usual
1521 	 * data packet size
1522 	 */
1523 	if (duration > MCS_DURATION(1, 0, 104))
1524 		return 1600;
1525 
1526 	/*
1527 	 * If the rate is slower than single-stream MCS7, or if the max throughput
1528 	 * rate success probability is less than 75%, limit A-MSDU to twice the usual
1529 	 * data packet size
1530 	 */
1531 	if (duration > MCS_DURATION(1, 0, 260) ||
1532 	    (minstrel_ht_get_prob_avg(mi, mi->max_tp_rate[0]) <
1533 	     MINSTREL_FRAC(75, 100)))
1534 		return 3200;
1535 
1536 	/*
1537 	 * HT A-MPDU limits maximum MPDU size under BA agreement to 4095 bytes.
1538 	 * Since aggregation sessions are started/stopped without txq flush, use
1539 	 * the limit here to avoid the complexity of having to de-aggregate
1540 	 * packets in the queue.
1541 	 */
1542 	if (!mi->sta->deflink.vht_cap.vht_supported)
1543 		return IEEE80211_MAX_MPDU_LEN_HT_BA;
1544 
1545 	/* unlimited */
1546 	return 0;
1547 }
1548 
1549 static void
1550 minstrel_ht_update_rates(struct minstrel_priv *mp, struct minstrel_ht_sta *mi)
1551 {
1552 	struct ieee80211_sta_rates *rates;
1553 	int i = 0;
1554 	int max_rates = min_t(int, mp->hw->max_rates, IEEE80211_TX_RATE_TABLE_SIZE);
1555 
1556 	rates = kzalloc(sizeof(*rates), GFP_ATOMIC);
1557 	if (!rates)
1558 		return;
1559 
1560 	/* Start with max_tp_rate[0] */
1561 	minstrel_ht_set_rate(mp, mi, rates, i++, mi->max_tp_rate[0]);
1562 
1563 	/* Fill up remaining, keep one entry for max_probe_rate */
1564 	for (; i < (max_rates - 1); i++)
1565 		minstrel_ht_set_rate(mp, mi, rates, i, mi->max_tp_rate[i]);
1566 
1567 	if (i < max_rates)
1568 		minstrel_ht_set_rate(mp, mi, rates, i++, mi->max_prob_rate);
1569 
1570 	if (i < IEEE80211_TX_RATE_TABLE_SIZE)
1571 		rates->rate[i].idx = -1;
1572 
1573 	mi->sta->deflink.agg.max_rc_amsdu_len = minstrel_ht_get_max_amsdu_len(mi);
1574 	ieee80211_sta_recalc_aggregates(mi->sta);
1575 	rate_control_set_rates(mp->hw, mi->sta, rates);
1576 }
1577 
1578 static u16
1579 minstrel_ht_get_sample_rate(struct minstrel_priv *mp, struct minstrel_ht_sta *mi)
1580 {
1581 	u8 seq;
1582 
1583 	if (mp->hw->max_rates > 1) {
1584 		seq = mi->sample_seq;
1585 		mi->sample_seq = (seq + 1) % ARRAY_SIZE(minstrel_sample_seq);
1586 		seq = minstrel_sample_seq[seq];
1587 	} else {
1588 		seq = MINSTREL_SAMPLE_TYPE_INC;
1589 	}
1590 
1591 	return __minstrel_ht_get_sample_rate(mi, seq);
1592 }
1593 
1594 static void
1595 minstrel_ht_get_rate(void *priv, struct ieee80211_sta *sta, void *priv_sta,
1596                      struct ieee80211_tx_rate_control *txrc)
1597 {
1598 	const struct mcs_group *sample_group;
1599 	struct ieee80211_tx_info *info = IEEE80211_SKB_CB(txrc->skb);
1600 	struct ieee80211_tx_rate *rate = &info->status.rates[0];
1601 	struct minstrel_ht_sta *mi = priv_sta;
1602 	struct minstrel_priv *mp = priv;
1603 	u16 sample_idx;
1604 
1605 	info->flags |= mi->tx_flags;
1606 
1607 #ifdef CONFIG_MAC80211_DEBUGFS
1608 	if (mp->fixed_rate_idx != -1)
1609 		return;
1610 #endif
1611 
1612 	/* Don't use EAPOL frames for sampling on non-mrr hw */
1613 	if (mp->hw->max_rates == 1 &&
1614 	    (info->control.flags & IEEE80211_TX_CTRL_PORT_CTRL_PROTO))
1615 		return;
1616 
1617 	if (time_is_after_jiffies(mi->sample_time))
1618 		return;
1619 
1620 	mi->sample_time = jiffies + MINSTREL_SAMPLE_INTERVAL;
1621 	sample_idx = minstrel_ht_get_sample_rate(mp, mi);
1622 	if (!sample_idx)
1623 		return;
1624 
1625 	sample_group = &minstrel_mcs_groups[MI_RATE_GROUP(sample_idx)];
1626 	sample_idx = MI_RATE_IDX(sample_idx);
1627 
1628 	if (sample_group == &minstrel_mcs_groups[MINSTREL_CCK_GROUP] &&
1629 	    (sample_idx >= 4) != txrc->short_preamble)
1630 		return;
1631 
1632 	info->flags |= IEEE80211_TX_CTL_RATE_CTRL_PROBE;
1633 	rate->count = 1;
1634 
1635 	if (sample_group == &minstrel_mcs_groups[MINSTREL_CCK_GROUP]) {
1636 		int idx = sample_idx % ARRAY_SIZE(mp->cck_rates);
1637 		rate->idx = mp->cck_rates[idx];
1638 	} else if (sample_group == &minstrel_mcs_groups[MINSTREL_OFDM_GROUP]) {
1639 		int idx = sample_idx % ARRAY_SIZE(mp->ofdm_rates[0]);
1640 		rate->idx = mp->ofdm_rates[mi->band][idx];
1641 	} else if (sample_group->flags & IEEE80211_TX_RC_VHT_MCS) {
1642 		ieee80211_rate_set_vht(rate, MI_RATE_IDX(sample_idx),
1643 				       sample_group->streams);
1644 	} else {
1645 		rate->idx = sample_idx + (sample_group->streams - 1) * 8;
1646 	}
1647 
1648 	rate->flags = sample_group->flags;
1649 }
1650 
1651 static void
1652 minstrel_ht_update_cck(struct minstrel_priv *mp, struct minstrel_ht_sta *mi,
1653 		       struct ieee80211_supported_band *sband,
1654 		       struct ieee80211_sta *sta)
1655 {
1656 	int i;
1657 
1658 	if (sband->band != NL80211_BAND_2GHZ)
1659 		return;
1660 
1661 	if (sta->deflink.ht_cap.ht_supported &&
1662 	    !ieee80211_hw_check(mp->hw, SUPPORTS_HT_CCK_RATES))
1663 		return;
1664 
1665 	for (i = 0; i < 4; i++) {
1666 		if (mp->cck_rates[i] == 0xff ||
1667 		    !rate_supported(sta, sband->band, mp->cck_rates[i]))
1668 			continue;
1669 
1670 		mi->supported[MINSTREL_CCK_GROUP] |= BIT(i);
1671 		if (sband->bitrates[i].flags & IEEE80211_RATE_SHORT_PREAMBLE)
1672 			mi->supported[MINSTREL_CCK_GROUP] |= BIT(i + 4);
1673 	}
1674 }
1675 
1676 static void
1677 minstrel_ht_update_ofdm(struct minstrel_priv *mp, struct minstrel_ht_sta *mi,
1678 			struct ieee80211_supported_band *sband,
1679 			struct ieee80211_sta *sta)
1680 {
1681 	const u8 *rates;
1682 	int i;
1683 
1684 	if (sta->deflink.ht_cap.ht_supported)
1685 		return;
1686 
1687 	rates = mp->ofdm_rates[sband->band];
1688 	for (i = 0; i < ARRAY_SIZE(mp->ofdm_rates[0]); i++) {
1689 		if (rates[i] == 0xff ||
1690 		    !rate_supported(sta, sband->band, rates[i]))
1691 			continue;
1692 
1693 		mi->supported[MINSTREL_OFDM_GROUP] |= BIT(i);
1694 	}
1695 }
1696 
1697 static void
1698 minstrel_ht_update_caps(void *priv, struct ieee80211_supported_band *sband,
1699 			struct cfg80211_chan_def *chandef,
1700 			struct ieee80211_sta *sta, void *priv_sta)
1701 {
1702 	struct minstrel_priv *mp = priv;
1703 	struct minstrel_ht_sta *mi = priv_sta;
1704 	struct ieee80211_mcs_info *mcs = &sta->deflink.ht_cap.mcs;
1705 	u16 ht_cap = sta->deflink.ht_cap.cap;
1706 	struct ieee80211_sta_vht_cap *vht_cap = &sta->deflink.vht_cap;
1707 	const struct ieee80211_rate *ctl_rate;
1708 	struct sta_info *sta_info;
1709 	bool ldpc, erp;
1710 	int use_vht;
1711 	int n_supported = 0;
1712 	int ack_dur;
1713 	int stbc;
1714 	int i;
1715 
1716 	BUILD_BUG_ON(ARRAY_SIZE(minstrel_mcs_groups) != MINSTREL_GROUPS_NB);
1717 
1718 	if (vht_cap->vht_supported)
1719 		use_vht = vht_cap->vht_mcs.tx_mcs_map != cpu_to_le16(~0);
1720 	else
1721 		use_vht = 0;
1722 
1723 	memset(mi, 0, sizeof(*mi));
1724 
1725 	mi->sta = sta;
1726 	mi->band = sband->band;
1727 	mi->last_stats_update = jiffies;
1728 
1729 	ack_dur = ieee80211_frame_duration(sband->band, 10, 60, 1, 1, 0);
1730 	mi->overhead = ieee80211_frame_duration(sband->band, 0, 60, 1, 1, 0);
1731 	mi->overhead += ack_dur;
1732 	mi->overhead_rtscts = mi->overhead + 2 * ack_dur;
1733 
1734 	ctl_rate = &sband->bitrates[rate_lowest_index(sband, sta)];
1735 	erp = ctl_rate->flags & IEEE80211_RATE_ERP_G;
1736 	ack_dur = ieee80211_frame_duration(sband->band, 10,
1737 					   ctl_rate->bitrate, erp, 1,
1738 					   ieee80211_chandef_get_shift(chandef));
1739 	mi->overhead_legacy = ack_dur;
1740 	mi->overhead_legacy_rtscts = mi->overhead_legacy + 2 * ack_dur;
1741 
1742 	mi->avg_ampdu_len = MINSTREL_FRAC(1, 1);
1743 
1744 	if (!use_vht) {
1745 		stbc = (ht_cap & IEEE80211_HT_CAP_RX_STBC) >>
1746 			IEEE80211_HT_CAP_RX_STBC_SHIFT;
1747 
1748 		ldpc = ht_cap & IEEE80211_HT_CAP_LDPC_CODING;
1749 	} else {
1750 		stbc = (vht_cap->cap & IEEE80211_VHT_CAP_RXSTBC_MASK) >>
1751 			IEEE80211_VHT_CAP_RXSTBC_SHIFT;
1752 
1753 		ldpc = vht_cap->cap & IEEE80211_VHT_CAP_RXLDPC;
1754 	}
1755 
1756 	mi->tx_flags |= stbc << IEEE80211_TX_CTL_STBC_SHIFT;
1757 	if (ldpc)
1758 		mi->tx_flags |= IEEE80211_TX_CTL_LDPC;
1759 
1760 	for (i = 0; i < ARRAY_SIZE(mi->groups); i++) {
1761 		u32 gflags = minstrel_mcs_groups[i].flags;
1762 		int bw, nss;
1763 
1764 		mi->supported[i] = 0;
1765 		if (minstrel_ht_is_legacy_group(i))
1766 			continue;
1767 
1768 		if (gflags & IEEE80211_TX_RC_SHORT_GI) {
1769 			if (gflags & IEEE80211_TX_RC_40_MHZ_WIDTH) {
1770 				if (!(ht_cap & IEEE80211_HT_CAP_SGI_40))
1771 					continue;
1772 			} else {
1773 				if (!(ht_cap & IEEE80211_HT_CAP_SGI_20))
1774 					continue;
1775 			}
1776 		}
1777 
1778 		if (gflags & IEEE80211_TX_RC_40_MHZ_WIDTH &&
1779 		    sta->deflink.bandwidth < IEEE80211_STA_RX_BW_40)
1780 			continue;
1781 
1782 		nss = minstrel_mcs_groups[i].streams;
1783 
1784 		/* Mark MCS > 7 as unsupported if STA is in static SMPS mode */
1785 		if (sta->deflink.smps_mode == IEEE80211_SMPS_STATIC && nss > 1)
1786 			continue;
1787 
1788 		/* HT rate */
1789 		if (gflags & IEEE80211_TX_RC_MCS) {
1790 			if (use_vht && minstrel_vht_only)
1791 				continue;
1792 
1793 			mi->supported[i] = mcs->rx_mask[nss - 1];
1794 			if (mi->supported[i])
1795 				n_supported++;
1796 			continue;
1797 		}
1798 
1799 		/* VHT rate */
1800 		if (!vht_cap->vht_supported ||
1801 		    WARN_ON(!(gflags & IEEE80211_TX_RC_VHT_MCS)) ||
1802 		    WARN_ON(gflags & IEEE80211_TX_RC_160_MHZ_WIDTH))
1803 			continue;
1804 
1805 		if (gflags & IEEE80211_TX_RC_80_MHZ_WIDTH) {
1806 			if (sta->deflink.bandwidth < IEEE80211_STA_RX_BW_80 ||
1807 			    ((gflags & IEEE80211_TX_RC_SHORT_GI) &&
1808 			     !(vht_cap->cap & IEEE80211_VHT_CAP_SHORT_GI_80))) {
1809 				continue;
1810 			}
1811 		}
1812 
1813 		if (gflags & IEEE80211_TX_RC_40_MHZ_WIDTH)
1814 			bw = BW_40;
1815 		else if (gflags & IEEE80211_TX_RC_80_MHZ_WIDTH)
1816 			bw = BW_80;
1817 		else
1818 			bw = BW_20;
1819 
1820 		mi->supported[i] = minstrel_get_valid_vht_rates(bw, nss,
1821 				vht_cap->vht_mcs.tx_mcs_map);
1822 
1823 		if (mi->supported[i])
1824 			n_supported++;
1825 	}
1826 
1827 	sta_info = container_of(sta, struct sta_info, sta);
1828 	mi->use_short_preamble = test_sta_flag(sta_info, WLAN_STA_SHORT_PREAMBLE) &&
1829 				 sta_info->sdata->vif.bss_conf.use_short_preamble;
1830 
1831 	minstrel_ht_update_cck(mp, mi, sband, sta);
1832 	minstrel_ht_update_ofdm(mp, mi, sband, sta);
1833 
1834 	/* create an initial rate table with the lowest supported rates */
1835 	minstrel_ht_update_stats(mp, mi);
1836 	minstrel_ht_update_rates(mp, mi);
1837 }
1838 
1839 static void
1840 minstrel_ht_rate_init(void *priv, struct ieee80211_supported_band *sband,
1841 		      struct cfg80211_chan_def *chandef,
1842                       struct ieee80211_sta *sta, void *priv_sta)
1843 {
1844 	minstrel_ht_update_caps(priv, sband, chandef, sta, priv_sta);
1845 }
1846 
1847 static void
1848 minstrel_ht_rate_update(void *priv, struct ieee80211_supported_band *sband,
1849 			struct cfg80211_chan_def *chandef,
1850                         struct ieee80211_sta *sta, void *priv_sta,
1851                         u32 changed)
1852 {
1853 	minstrel_ht_update_caps(priv, sband, chandef, sta, priv_sta);
1854 }
1855 
1856 static void *
1857 minstrel_ht_alloc_sta(void *priv, struct ieee80211_sta *sta, gfp_t gfp)
1858 {
1859 	struct ieee80211_supported_band *sband;
1860 	struct minstrel_ht_sta *mi;
1861 	struct minstrel_priv *mp = priv;
1862 	struct ieee80211_hw *hw = mp->hw;
1863 	int max_rates = 0;
1864 	int i;
1865 
1866 	for (i = 0; i < NUM_NL80211_BANDS; i++) {
1867 		sband = hw->wiphy->bands[i];
1868 		if (sband && sband->n_bitrates > max_rates)
1869 			max_rates = sband->n_bitrates;
1870 	}
1871 
1872 	return kzalloc(sizeof(*mi), gfp);
1873 }
1874 
1875 static void
1876 minstrel_ht_free_sta(void *priv, struct ieee80211_sta *sta, void *priv_sta)
1877 {
1878 	kfree(priv_sta);
1879 }
1880 
1881 static void
1882 minstrel_ht_fill_rate_array(u8 *dest, struct ieee80211_supported_band *sband,
1883 			    const s16 *bitrates, int n_rates, u32 rate_flags)
1884 {
1885 	int i, j;
1886 
1887 	for (i = 0; i < sband->n_bitrates; i++) {
1888 		struct ieee80211_rate *rate = &sband->bitrates[i];
1889 
1890 		if ((rate_flags & sband->bitrates[i].flags) != rate_flags)
1891 			continue;
1892 
1893 		for (j = 0; j < n_rates; j++) {
1894 			if (rate->bitrate != bitrates[j])
1895 				continue;
1896 
1897 			dest[j] = i;
1898 			break;
1899 		}
1900 	}
1901 }
1902 
1903 static void
1904 minstrel_ht_init_cck_rates(struct minstrel_priv *mp)
1905 {
1906 	static const s16 bitrates[4] = { 10, 20, 55, 110 };
1907 	struct ieee80211_supported_band *sband;
1908 	u32 rate_flags = ieee80211_chandef_rate_flags(&mp->hw->conf.chandef);
1909 
1910 	memset(mp->cck_rates, 0xff, sizeof(mp->cck_rates));
1911 	sband = mp->hw->wiphy->bands[NL80211_BAND_2GHZ];
1912 	if (!sband)
1913 		return;
1914 
1915 	BUILD_BUG_ON(ARRAY_SIZE(mp->cck_rates) != ARRAY_SIZE(bitrates));
1916 	minstrel_ht_fill_rate_array(mp->cck_rates, sband,
1917 				    minstrel_cck_bitrates,
1918 				    ARRAY_SIZE(minstrel_cck_bitrates),
1919 				    rate_flags);
1920 }
1921 
1922 static void
1923 minstrel_ht_init_ofdm_rates(struct minstrel_priv *mp, enum nl80211_band band)
1924 {
1925 	static const s16 bitrates[8] = { 60, 90, 120, 180, 240, 360, 480, 540 };
1926 	struct ieee80211_supported_band *sband;
1927 	u32 rate_flags = ieee80211_chandef_rate_flags(&mp->hw->conf.chandef);
1928 
1929 	memset(mp->ofdm_rates[band], 0xff, sizeof(mp->ofdm_rates[band]));
1930 	sband = mp->hw->wiphy->bands[band];
1931 	if (!sband)
1932 		return;
1933 
1934 	BUILD_BUG_ON(ARRAY_SIZE(mp->ofdm_rates[band]) != ARRAY_SIZE(bitrates));
1935 	minstrel_ht_fill_rate_array(mp->ofdm_rates[band], sband,
1936 				    minstrel_ofdm_bitrates,
1937 				    ARRAY_SIZE(minstrel_ofdm_bitrates),
1938 				    rate_flags);
1939 }
1940 
1941 static void *
1942 minstrel_ht_alloc(struct ieee80211_hw *hw)
1943 {
1944 	struct minstrel_priv *mp;
1945 	int i;
1946 
1947 	mp = kzalloc(sizeof(struct minstrel_priv), GFP_ATOMIC);
1948 	if (!mp)
1949 		return NULL;
1950 
1951 	/* contention window settings
1952 	 * Just an approximation. Using the per-queue values would complicate
1953 	 * the calculations and is probably unnecessary */
1954 	mp->cw_min = 15;
1955 	mp->cw_max = 1023;
1956 
1957 	/* maximum time that the hw is allowed to stay in one MRR segment */
1958 	mp->segment_size = 6000;
1959 
1960 	if (hw->max_rate_tries > 0)
1961 		mp->max_retry = hw->max_rate_tries;
1962 	else
1963 		/* safe default, does not necessarily have to match hw properties */
1964 		mp->max_retry = 7;
1965 
1966 	mp->hw = hw;
1967 	mp->update_interval = HZ / 20;
1968 
1969 	minstrel_ht_init_cck_rates(mp);
1970 	for (i = 0; i < ARRAY_SIZE(mp->hw->wiphy->bands); i++)
1971 	    minstrel_ht_init_ofdm_rates(mp, i);
1972 
1973 	return mp;
1974 }
1975 
1976 #ifdef CONFIG_MAC80211_DEBUGFS
1977 static void minstrel_ht_add_debugfs(struct ieee80211_hw *hw, void *priv,
1978 				    struct dentry *debugfsdir)
1979 {
1980 	struct minstrel_priv *mp = priv;
1981 
1982 	mp->fixed_rate_idx = (u32) -1;
1983 	debugfs_create_u32("fixed_rate_idx", S_IRUGO | S_IWUGO, debugfsdir,
1984 			   &mp->fixed_rate_idx);
1985 }
1986 #endif
1987 
1988 static void
1989 minstrel_ht_free(void *priv)
1990 {
1991 	kfree(priv);
1992 }
1993 
1994 static u32 minstrel_ht_get_expected_throughput(void *priv_sta)
1995 {
1996 	struct minstrel_ht_sta *mi = priv_sta;
1997 	int i, j, prob, tp_avg;
1998 
1999 	i = MI_RATE_GROUP(mi->max_tp_rate[0]);
2000 	j = MI_RATE_IDX(mi->max_tp_rate[0]);
2001 	prob = mi->groups[i].rates[j].prob_avg;
2002 
2003 	/* convert tp_avg from pkt per second in kbps */
2004 	tp_avg = minstrel_ht_get_tp_avg(mi, i, j, prob) * 10;
2005 	tp_avg = tp_avg * AVG_PKT_SIZE * 8 / 1024;
2006 
2007 	return tp_avg;
2008 }
2009 
2010 static const struct rate_control_ops mac80211_minstrel_ht = {
2011 	.name = "minstrel_ht",
2012 	.capa = RATE_CTRL_CAPA_AMPDU_TRIGGER,
2013 	.tx_status_ext = minstrel_ht_tx_status,
2014 	.get_rate = minstrel_ht_get_rate,
2015 	.rate_init = minstrel_ht_rate_init,
2016 	.rate_update = minstrel_ht_rate_update,
2017 	.alloc_sta = minstrel_ht_alloc_sta,
2018 	.free_sta = minstrel_ht_free_sta,
2019 	.alloc = minstrel_ht_alloc,
2020 	.free = minstrel_ht_free,
2021 #ifdef CONFIG_MAC80211_DEBUGFS
2022 	.add_debugfs = minstrel_ht_add_debugfs,
2023 	.add_sta_debugfs = minstrel_ht_add_sta_debugfs,
2024 #endif
2025 	.get_expected_throughput = minstrel_ht_get_expected_throughput,
2026 };
2027 
2028 
2029 static void __init init_sample_table(void)
2030 {
2031 	int col, i, new_idx;
2032 	u8 rnd[MCS_GROUP_RATES];
2033 
2034 	memset(sample_table, 0xff, sizeof(sample_table));
2035 	for (col = 0; col < SAMPLE_COLUMNS; col++) {
2036 		get_random_bytes(rnd, sizeof(rnd));
2037 		for (i = 0; i < MCS_GROUP_RATES; i++) {
2038 			new_idx = (i + rnd[i]) % MCS_GROUP_RATES;
2039 			while (sample_table[col][new_idx] != 0xff)
2040 				new_idx = (new_idx + 1) % MCS_GROUP_RATES;
2041 
2042 			sample_table[col][new_idx] = i;
2043 		}
2044 	}
2045 }
2046 
2047 int __init
2048 rc80211_minstrel_init(void)
2049 {
2050 	init_sample_table();
2051 	return ieee80211_rate_control_register(&mac80211_minstrel_ht);
2052 }
2053 
2054 void
2055 rc80211_minstrel_exit(void)
2056 {
2057 	ieee80211_rate_control_unregister(&mac80211_minstrel_ht);
2058 }
2059