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