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1/*
2 * Copyright (C) 2008 Felix Fietkau <nbd@openwrt.org>
3 *
4 * This program is free software; you can redistribute it and/or modify
5 * it under the terms of the GNU General Public License version 2 as
6 * published by the Free Software Foundation.
7 *
8 * Based on minstrel.c:
9 * Copyright (C) 2005-2007 Derek Smithies <derek@indranet.co.nz>
10 * Sponsored by Indranet Technologies Ltd
11 *
12 * Based on sample.c:
13 * Copyright (c) 2005 John Bicket
14 * All rights reserved.
15 *
16 * Redistribution and use in source and binary forms, with or without
17 * modification, are permitted provided that the following conditions
18 * are met:
19 * 1. Redistributions of source code must retain the above copyright
20 * notice, this list of conditions and the following disclaimer,
21 * without modification.
22 * 2. Redistributions in binary form must reproduce at minimum a disclaimer
23 * similar to the "NO WARRANTY" disclaimer below ("Disclaimer") and any
24 * redistribution must be conditioned upon including a substantially
25 * similar Disclaimer requirement for further binary redistribution.
26 * 3. Neither the names of the above-listed copyright holders nor the names
27 * of any contributors may be used to endorse or promote products derived
28 * from this software without specific prior written permission.
29 *
30 * Alternatively, this software may be distributed under the terms of the
31 * GNU General Public License ("GPL") version 2 as published by the Free
32 * Software Foundation.
33 *
34 * NO WARRANTY
35 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
36 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
37 * LIMITED TO, THE IMPLIED WARRANTIES OF NONINFRINGEMENT, MERCHANTIBILITY
38 * AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL
39 * THE COPYRIGHT HOLDERS OR CONTRIBUTORS BE LIABLE FOR SPECIAL, EXEMPLARY,
40 * OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
41 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
42 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER
43 * IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
44 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF
45 * THE POSSIBILITY OF SUCH DAMAGES.
46 */
47#include <linux/netdevice.h>
48#include <linux/types.h>
49#include <linux/skbuff.h>
50#include <linux/debugfs.h>
51#include <linux/random.h>
52#include <linux/ieee80211.h>
53#include <linux/slab.h>
54#include <net/mac80211.h>
55#include "rate.h"
56#include "rc80211_minstrel.h"
57
58#define SAMPLE_TBL(_mi, _idx, _col) \
59 _mi->sample_table[(_idx * SAMPLE_COLUMNS) + _col]
60
61/* convert mac80211 rate index to local array index */
62static inline int
63rix_to_ndx(struct minstrel_sta_info *mi, int rix)
64{
65 int i = rix;
66 for (i = rix; i >= 0; i--)
67 if (mi->r[i].rix == rix)
68 break;
69 return i;
70}
71
72/* return current EMWA throughput */
73int minstrel_get_tp_avg(struct minstrel_rate *mr, int prob_ewma)
74{
75 int usecs;
76
77 usecs = mr->perfect_tx_time;
78 if (!usecs)
79 usecs = 1000000;
80
81 /* reset thr. below 10% success */
82 if (mr->stats.prob_ewma < MINSTREL_FRAC(10, 100))
83 return 0;
84
85 if (prob_ewma > MINSTREL_FRAC(90, 100))
86 return MINSTREL_TRUNC(100000 * (MINSTREL_FRAC(90, 100) / usecs));
87 else
88 return MINSTREL_TRUNC(100000 * (prob_ewma / usecs));
89}
90
91/* find & sort topmost throughput rates */
92static inline void
93minstrel_sort_best_tp_rates(struct minstrel_sta_info *mi, int i, u8 *tp_list)
94{
95 int j;
96 struct minstrel_rate_stats *tmp_mrs;
97 struct minstrel_rate_stats *cur_mrs = &mi->r[i].stats;
98
99 for (j = MAX_THR_RATES; j > 0; --j) {
100 tmp_mrs = &mi->r[tp_list[j - 1]].stats;
101 if (minstrel_get_tp_avg(&mi->r[i], cur_mrs->prob_ewma) <=
102 minstrel_get_tp_avg(&mi->r[tp_list[j - 1]], tmp_mrs->prob_ewma))
103 break;
104 }
105
106 if (j < MAX_THR_RATES - 1)
107 memmove(&tp_list[j + 1], &tp_list[j], MAX_THR_RATES - (j + 1));
108 if (j < MAX_THR_RATES)
109 tp_list[j] = i;
110}
111
112static void
113minstrel_set_rate(struct minstrel_sta_info *mi, struct ieee80211_sta_rates *ratetbl,
114 int offset, int idx)
115{
116 struct minstrel_rate *r = &mi->r[idx];
117
118 ratetbl->rate[offset].idx = r->rix;
119 ratetbl->rate[offset].count = r->adjusted_retry_count;
120 ratetbl->rate[offset].count_cts = r->retry_count_cts;
121 ratetbl->rate[offset].count_rts = r->stats.retry_count_rtscts;
122}
123
124static void
125minstrel_update_rates(struct minstrel_priv *mp, struct minstrel_sta_info *mi)
126{
127 struct ieee80211_sta_rates *ratetbl;
128 int i = 0;
129
130 ratetbl = kzalloc(sizeof(*ratetbl), GFP_ATOMIC);
131 if (!ratetbl)
132 return;
133
134 /* Start with max_tp_rate */
135 minstrel_set_rate(mi, ratetbl, i++, mi->max_tp_rate[0]);
136
137 if (mp->hw->max_rates >= 3) {
138 /* At least 3 tx rates supported, use max_tp_rate2 next */
139 minstrel_set_rate(mi, ratetbl, i++, mi->max_tp_rate[1]);
140 }
141
142 if (mp->hw->max_rates >= 2) {
143 /* At least 2 tx rates supported, use max_prob_rate next */
144 minstrel_set_rate(mi, ratetbl, i++, mi->max_prob_rate);
145 }
146
147 /* Use lowest rate last */
148 ratetbl->rate[i].idx = mi->lowest_rix;
149 ratetbl->rate[i].count = mp->max_retry;
150 ratetbl->rate[i].count_cts = mp->max_retry;
151 ratetbl->rate[i].count_rts = mp->max_retry;
152
153 rate_control_set_rates(mp->hw, mi->sta, ratetbl);
154}
155
156/*
157* Recalculate statistics and counters of a given rate
158*/
159void
160minstrel_calc_rate_stats(struct minstrel_rate_stats *mrs)
161{
162 if (unlikely(mrs->attempts > 0)) {
163 mrs->sample_skipped = 0;
164 mrs->cur_prob = MINSTREL_FRAC(mrs->success, mrs->attempts);
165 if (unlikely(!mrs->att_hist)) {
166 mrs->prob_ewma = mrs->cur_prob;
167 } else {
168 /* update exponential weighted moving variance */
169 mrs->prob_ewmsd = minstrel_ewmsd(mrs->prob_ewmsd,
170 mrs->cur_prob,
171 mrs->prob_ewma,
172 EWMA_LEVEL);
173
174 /*update exponential weighted moving avarage */
175 mrs->prob_ewma = minstrel_ewma(mrs->prob_ewma,
176 mrs->cur_prob,
177 EWMA_LEVEL);
178 }
179 mrs->att_hist += mrs->attempts;
180 mrs->succ_hist += mrs->success;
181 } else {
182 mrs->sample_skipped++;
183 }
184
185 mrs->last_success = mrs->success;
186 mrs->last_attempts = mrs->attempts;
187 mrs->success = 0;
188 mrs->attempts = 0;
189}
190
191static void
192minstrel_update_stats(struct minstrel_priv *mp, struct minstrel_sta_info *mi)
193{
194 u8 tmp_tp_rate[MAX_THR_RATES];
195 u8 tmp_prob_rate = 0;
196 int i, tmp_cur_tp, tmp_prob_tp;
197
198 for (i = 0; i < MAX_THR_RATES; i++)
199 tmp_tp_rate[i] = 0;
200
201 for (i = 0; i < mi->n_rates; i++) {
202 struct minstrel_rate *mr = &mi->r[i];
203 struct minstrel_rate_stats *mrs = &mi->r[i].stats;
204 struct minstrel_rate_stats *tmp_mrs = &mi->r[tmp_prob_rate].stats;
205
206 /* Update statistics of success probability per rate */
207 minstrel_calc_rate_stats(mrs);
208
209 /* Sample less often below the 10% chance of success.
210 * Sample less often above the 95% chance of success. */
211 if (mrs->prob_ewma > MINSTREL_FRAC(95, 100) ||
212 mrs->prob_ewma < MINSTREL_FRAC(10, 100)) {
213 mr->adjusted_retry_count = mrs->retry_count >> 1;
214 if (mr->adjusted_retry_count > 2)
215 mr->adjusted_retry_count = 2;
216 mr->sample_limit = 4;
217 } else {
218 mr->sample_limit = -1;
219 mr->adjusted_retry_count = mrs->retry_count;
220 }
221 if (!mr->adjusted_retry_count)
222 mr->adjusted_retry_count = 2;
223
224 minstrel_sort_best_tp_rates(mi, i, tmp_tp_rate);
225
226 /* To determine the most robust rate (max_prob_rate) used at
227 * 3rd mmr stage we distinct between two cases:
228 * (1) if any success probabilitiy >= 95%, out of those rates
229 * choose the maximum throughput rate as max_prob_rate
230 * (2) if all success probabilities < 95%, the rate with
231 * highest success probability is chosen as max_prob_rate */
232 if (mrs->prob_ewma >= MINSTREL_FRAC(95, 100)) {
233 tmp_cur_tp = minstrel_get_tp_avg(mr, mrs->prob_ewma);
234 tmp_prob_tp = minstrel_get_tp_avg(&mi->r[tmp_prob_rate],
235 tmp_mrs->prob_ewma);
236 if (tmp_cur_tp >= tmp_prob_tp)
237 tmp_prob_rate = i;
238 } else {
239 if (mrs->prob_ewma >= tmp_mrs->prob_ewma)
240 tmp_prob_rate = i;
241 }
242 }
243
244 /* Assign the new rate set */
245 memcpy(mi->max_tp_rate, tmp_tp_rate, sizeof(mi->max_tp_rate));
246 mi->max_prob_rate = tmp_prob_rate;
247
248#ifdef CONFIG_MAC80211_DEBUGFS
249 /* use fixed index if set */
250 if (mp->fixed_rate_idx != -1) {
251 mi->max_tp_rate[0] = mp->fixed_rate_idx;
252 mi->max_tp_rate[1] = mp->fixed_rate_idx;
253 mi->max_prob_rate = mp->fixed_rate_idx;
254 }
255#endif
256
257 /* Reset update timer */
258 mi->last_stats_update = jiffies;
259
260 minstrel_update_rates(mp, mi);
261}
262
263static void
264minstrel_tx_status(void *priv, struct ieee80211_supported_band *sband,
265 struct ieee80211_sta *sta, void *priv_sta,
266 struct ieee80211_tx_info *info)
267{
268 struct minstrel_priv *mp = priv;
269 struct minstrel_sta_info *mi = priv_sta;
270 struct ieee80211_tx_rate *ar = info->status.rates;
271 int i, ndx;
272 int success;
273
274 success = !!(info->flags & IEEE80211_TX_STAT_ACK);
275
276 for (i = 0; i < IEEE80211_TX_MAX_RATES; i++) {
277 if (ar[i].idx < 0)
278 break;
279
280 ndx = rix_to_ndx(mi, ar[i].idx);
281 if (ndx < 0)
282 continue;
283
284 mi->r[ndx].stats.attempts += ar[i].count;
285
286 if ((i != IEEE80211_TX_MAX_RATES - 1) && (ar[i + 1].idx < 0))
287 mi->r[ndx].stats.success += success;
288 }
289
290 if ((info->flags & IEEE80211_TX_CTL_RATE_CTRL_PROBE) && (i >= 0))
291 mi->sample_packets++;
292
293 if (mi->sample_deferred > 0)
294 mi->sample_deferred--;
295
296 if (time_after(jiffies, mi->last_stats_update +
297 (mp->update_interval * HZ) / 1000))
298 minstrel_update_stats(mp, mi);
299}
300
301
302static inline unsigned int
303minstrel_get_retry_count(struct minstrel_rate *mr,
304 struct ieee80211_tx_info *info)
305{
306 u8 retry = mr->adjusted_retry_count;
307
308 if (info->control.use_rts)
309 retry = max_t(u8, 2, min(mr->stats.retry_count_rtscts, retry));
310 else if (info->control.use_cts_prot)
311 retry = max_t(u8, 2, min(mr->retry_count_cts, retry));
312 return retry;
313}
314
315
316static int
317minstrel_get_next_sample(struct minstrel_sta_info *mi)
318{
319 unsigned int sample_ndx;
320 sample_ndx = SAMPLE_TBL(mi, mi->sample_row, mi->sample_column);
321 mi->sample_row++;
322 if ((int) mi->sample_row >= mi->n_rates) {
323 mi->sample_row = 0;
324 mi->sample_column++;
325 if (mi->sample_column >= SAMPLE_COLUMNS)
326 mi->sample_column = 0;
327 }
328 return sample_ndx;
329}
330
331static void
332minstrel_get_rate(void *priv, struct ieee80211_sta *sta,
333 void *priv_sta, struct ieee80211_tx_rate_control *txrc)
334{
335 struct sk_buff *skb = txrc->skb;
336 struct ieee80211_tx_info *info = IEEE80211_SKB_CB(skb);
337 struct minstrel_sta_info *mi = priv_sta;
338 struct minstrel_priv *mp = priv;
339 struct ieee80211_tx_rate *rate = &info->control.rates[0];
340 struct minstrel_rate *msr, *mr;
341 unsigned int ndx;
342 bool mrr_capable;
343 bool prev_sample;
344 int delta;
345 int sampling_ratio;
346
347 /* management/no-ack frames do not use rate control */
348 if (rate_control_send_low(sta, priv_sta, txrc))
349 return;
350
351 /* check multi-rate-retry capabilities & adjust lookaround_rate */
352 mrr_capable = mp->has_mrr &&
353 !txrc->rts &&
354 !txrc->bss_conf->use_cts_prot;
355 if (mrr_capable)
356 sampling_ratio = mp->lookaround_rate_mrr;
357 else
358 sampling_ratio = mp->lookaround_rate;
359
360 /* increase sum packet counter */
361 mi->total_packets++;
362
363#ifdef CONFIG_MAC80211_DEBUGFS
364 if (mp->fixed_rate_idx != -1)
365 return;
366#endif
367
368 delta = (mi->total_packets * sampling_ratio / 100) -
369 (mi->sample_packets + mi->sample_deferred / 2);
370
371 /* delta < 0: no sampling required */
372 prev_sample = mi->prev_sample;
373 mi->prev_sample = false;
374 if (delta < 0 || (!mrr_capable && prev_sample))
375 return;
376
377 if (mi->total_packets >= 10000) {
378 mi->sample_deferred = 0;
379 mi->sample_packets = 0;
380 mi->total_packets = 0;
381 } else if (delta > mi->n_rates * 2) {
382 /* With multi-rate retry, not every planned sample
383 * attempt actually gets used, due to the way the retry
384 * chain is set up - [max_tp,sample,prob,lowest] for
385 * sample_rate < max_tp.
386 *
387 * If there's too much sampling backlog and the link
388 * starts getting worse, minstrel would start bursting
389 * out lots of sampling frames, which would result
390 * in a large throughput loss. */
391 mi->sample_packets += (delta - mi->n_rates * 2);
392 }
393
394 /* get next random rate sample */
395 ndx = minstrel_get_next_sample(mi);
396 msr = &mi->r[ndx];
397 mr = &mi->r[mi->max_tp_rate[0]];
398
399 /* Decide if direct ( 1st mrr stage) or indirect (2nd mrr stage)
400 * rate sampling method should be used.
401 * Respect such rates that are not sampled for 20 interations.
402 */
403 if (mrr_capable &&
404 msr->perfect_tx_time > mr->perfect_tx_time &&
405 msr->stats.sample_skipped < 20) {
406 /* Only use IEEE80211_TX_CTL_RATE_CTRL_PROBE to mark
407 * packets that have the sampling rate deferred to the
408 * second MRR stage. Increase the sample counter only
409 * if the deferred sample rate was actually used.
410 * Use the sample_deferred counter to make sure that
411 * the sampling is not done in large bursts */
412 info->flags |= IEEE80211_TX_CTL_RATE_CTRL_PROBE;
413 rate++;
414 mi->sample_deferred++;
415 } else {
416 if (!msr->sample_limit)
417 return;
418
419 mi->sample_packets++;
420 if (msr->sample_limit > 0)
421 msr->sample_limit--;
422 }
423
424 /* If we're not using MRR and the sampling rate already
425 * has a probability of >95%, we shouldn't be attempting
426 * to use it, as this only wastes precious airtime */
427 if (!mrr_capable &&
428 (mi->r[ndx].stats.prob_ewma > MINSTREL_FRAC(95, 100)))
429 return;
430
431 mi->prev_sample = true;
432
433 rate->idx = mi->r[ndx].rix;
434 rate->count = minstrel_get_retry_count(&mi->r[ndx], info);
435}
436
437
438static void
439calc_rate_durations(enum nl80211_band band,
440 struct minstrel_rate *d,
441 struct ieee80211_rate *rate,
442 struct cfg80211_chan_def *chandef)
443{
444 int erp = !!(rate->flags & IEEE80211_RATE_ERP_G);
445 int shift = ieee80211_chandef_get_shift(chandef);
446
447 d->perfect_tx_time = ieee80211_frame_duration(band, 1200,
448 DIV_ROUND_UP(rate->bitrate, 1 << shift), erp, 1,
449 shift);
450 d->ack_time = ieee80211_frame_duration(band, 10,
451 DIV_ROUND_UP(rate->bitrate, 1 << shift), erp, 1,
452 shift);
453}
454
455static void
456init_sample_table(struct minstrel_sta_info *mi)
457{
458 unsigned int i, col, new_idx;
459 u8 rnd[8];
460
461 mi->sample_column = 0;
462 mi->sample_row = 0;
463 memset(mi->sample_table, 0xff, SAMPLE_COLUMNS * mi->n_rates);
464
465 for (col = 0; col < SAMPLE_COLUMNS; col++) {
466 prandom_bytes(rnd, sizeof(rnd));
467 for (i = 0; i < mi->n_rates; i++) {
468 new_idx = (i + rnd[i & 7]) % mi->n_rates;
469 while (SAMPLE_TBL(mi, new_idx, col) != 0xff)
470 new_idx = (new_idx + 1) % mi->n_rates;
471
472 SAMPLE_TBL(mi, new_idx, col) = i;
473 }
474 }
475}
476
477static void
478minstrel_rate_init(void *priv, struct ieee80211_supported_band *sband,
479 struct cfg80211_chan_def *chandef,
480 struct ieee80211_sta *sta, void *priv_sta)
481{
482 struct minstrel_sta_info *mi = priv_sta;
483 struct minstrel_priv *mp = priv;
484 struct ieee80211_rate *ctl_rate;
485 unsigned int i, n = 0;
486 unsigned int t_slot = 9; /* FIXME: get real slot time */
487 u32 rate_flags;
488
489 mi->sta = sta;
490 mi->lowest_rix = rate_lowest_index(sband, sta);
491 ctl_rate = &sband->bitrates[mi->lowest_rix];
492 mi->sp_ack_dur = ieee80211_frame_duration(sband->band, 10,
493 ctl_rate->bitrate,
494 !!(ctl_rate->flags & IEEE80211_RATE_ERP_G), 1,
495 ieee80211_chandef_get_shift(chandef));
496
497 rate_flags = ieee80211_chandef_rate_flags(&mp->hw->conf.chandef);
498 memset(mi->max_tp_rate, 0, sizeof(mi->max_tp_rate));
499 mi->max_prob_rate = 0;
500
501 for (i = 0; i < sband->n_bitrates; i++) {
502 struct minstrel_rate *mr = &mi->r[n];
503 struct minstrel_rate_stats *mrs = &mi->r[n].stats;
504 unsigned int tx_time = 0, tx_time_cts = 0, tx_time_rtscts = 0;
505 unsigned int tx_time_single;
506 unsigned int cw = mp->cw_min;
507 int shift;
508
509 if (!rate_supported(sta, sband->band, i))
510 continue;
511 if ((rate_flags & sband->bitrates[i].flags) != rate_flags)
512 continue;
513
514 n++;
515 memset(mr, 0, sizeof(*mr));
516 memset(mrs, 0, sizeof(*mrs));
517
518 mr->rix = i;
519 shift = ieee80211_chandef_get_shift(chandef);
520 mr->bitrate = DIV_ROUND_UP(sband->bitrates[i].bitrate,
521 (1 << shift) * 5);
522 calc_rate_durations(sband->band, mr, &sband->bitrates[i],
523 chandef);
524
525 /* calculate maximum number of retransmissions before
526 * fallback (based on maximum segment size) */
527 mr->sample_limit = -1;
528 mrs->retry_count = 1;
529 mr->retry_count_cts = 1;
530 mrs->retry_count_rtscts = 1;
531 tx_time = mr->perfect_tx_time + mi->sp_ack_dur;
532 do {
533 /* add one retransmission */
534 tx_time_single = mr->ack_time + mr->perfect_tx_time;
535
536 /* contention window */
537 tx_time_single += (t_slot * cw) >> 1;
538 cw = min((cw << 1) | 1, mp->cw_max);
539
540 tx_time += tx_time_single;
541 tx_time_cts += tx_time_single + mi->sp_ack_dur;
542 tx_time_rtscts += tx_time_single + 2 * mi->sp_ack_dur;
543 if ((tx_time_cts < mp->segment_size) &&
544 (mr->retry_count_cts < mp->max_retry))
545 mr->retry_count_cts++;
546 if ((tx_time_rtscts < mp->segment_size) &&
547 (mrs->retry_count_rtscts < mp->max_retry))
548 mrs->retry_count_rtscts++;
549 } while ((tx_time < mp->segment_size) &&
550 (++mr->stats.retry_count < mp->max_retry));
551 mr->adjusted_retry_count = mrs->retry_count;
552 if (!(sband->bitrates[i].flags & IEEE80211_RATE_ERP_G))
553 mr->retry_count_cts = mrs->retry_count;
554 }
555
556 for (i = n; i < sband->n_bitrates; i++) {
557 struct minstrel_rate *mr = &mi->r[i];
558 mr->rix = -1;
559 }
560
561 mi->n_rates = n;
562 mi->last_stats_update = jiffies;
563
564 init_sample_table(mi);
565 minstrel_update_rates(mp, mi);
566}
567
568static void *
569minstrel_alloc_sta(void *priv, struct ieee80211_sta *sta, gfp_t gfp)
570{
571 struct ieee80211_supported_band *sband;
572 struct minstrel_sta_info *mi;
573 struct minstrel_priv *mp = priv;
574 struct ieee80211_hw *hw = mp->hw;
575 int max_rates = 0;
576 int i;
577
578 mi = kzalloc(sizeof(struct minstrel_sta_info), gfp);
579 if (!mi)
580 return NULL;
581
582 for (i = 0; i < NUM_NL80211_BANDS; i++) {
583 sband = hw->wiphy->bands[i];
584 if (sband && sband->n_bitrates > max_rates)
585 max_rates = sband->n_bitrates;
586 }
587
588 mi->r = kzalloc(sizeof(struct minstrel_rate) * max_rates, gfp);
589 if (!mi->r)
590 goto error;
591
592 mi->sample_table = kmalloc(SAMPLE_COLUMNS * max_rates, gfp);
593 if (!mi->sample_table)
594 goto error1;
595
596 mi->last_stats_update = jiffies;
597 return mi;
598
599error1:
600 kfree(mi->r);
601error:
602 kfree(mi);
603 return NULL;
604}
605
606static void
607minstrel_free_sta(void *priv, struct ieee80211_sta *sta, void *priv_sta)
608{
609 struct minstrel_sta_info *mi = priv_sta;
610
611 kfree(mi->sample_table);
612 kfree(mi->r);
613 kfree(mi);
614}
615
616static void
617minstrel_init_cck_rates(struct minstrel_priv *mp)
618{
619 static const int bitrates[4] = { 10, 20, 55, 110 };
620 struct ieee80211_supported_band *sband;
621 u32 rate_flags = ieee80211_chandef_rate_flags(&mp->hw->conf.chandef);
622 int i, j;
623
624 sband = mp->hw->wiphy->bands[NL80211_BAND_2GHZ];
625 if (!sband)
626 return;
627
628 for (i = 0, j = 0; i < sband->n_bitrates; i++) {
629 struct ieee80211_rate *rate = &sband->bitrates[i];
630
631 if (rate->flags & IEEE80211_RATE_ERP_G)
632 continue;
633
634 if ((rate_flags & sband->bitrates[i].flags) != rate_flags)
635 continue;
636
637 for (j = 0; j < ARRAY_SIZE(bitrates); j++) {
638 if (rate->bitrate != bitrates[j])
639 continue;
640
641 mp->cck_rates[j] = i;
642 break;
643 }
644 }
645}
646
647static void *
648minstrel_alloc(struct ieee80211_hw *hw, struct dentry *debugfsdir)
649{
650 struct minstrel_priv *mp;
651
652 mp = kzalloc(sizeof(struct minstrel_priv), GFP_ATOMIC);
653 if (!mp)
654 return NULL;
655
656 /* contention window settings
657 * Just an approximation. Using the per-queue values would complicate
658 * the calculations and is probably unnecessary */
659 mp->cw_min = 15;
660 mp->cw_max = 1023;
661
662 /* number of packets (in %) to use for sampling other rates
663 * sample less often for non-mrr packets, because the overhead
664 * is much higher than with mrr */
665 mp->lookaround_rate = 5;
666 mp->lookaround_rate_mrr = 10;
667
668 /* maximum time that the hw is allowed to stay in one MRR segment */
669 mp->segment_size = 6000;
670
671 if (hw->max_rate_tries > 0)
672 mp->max_retry = hw->max_rate_tries;
673 else
674 /* safe default, does not necessarily have to match hw properties */
675 mp->max_retry = 7;
676
677 if (hw->max_rates >= 4)
678 mp->has_mrr = true;
679
680 mp->hw = hw;
681 mp->update_interval = 100;
682
683#ifdef CONFIG_MAC80211_DEBUGFS
684 mp->fixed_rate_idx = (u32) -1;
685 mp->dbg_fixed_rate = debugfs_create_u32("fixed_rate_idx",
686 S_IRUGO | S_IWUGO, debugfsdir, &mp->fixed_rate_idx);
687#endif
688
689 minstrel_init_cck_rates(mp);
690
691 return mp;
692}
693
694static void
695minstrel_free(void *priv)
696{
697#ifdef CONFIG_MAC80211_DEBUGFS
698 debugfs_remove(((struct minstrel_priv *)priv)->dbg_fixed_rate);
699#endif
700 kfree(priv);
701}
702
703static u32 minstrel_get_expected_throughput(void *priv_sta)
704{
705 struct minstrel_sta_info *mi = priv_sta;
706 struct minstrel_rate_stats *tmp_mrs;
707 int idx = mi->max_tp_rate[0];
708 int tmp_cur_tp;
709
710 /* convert pkt per sec in kbps (1200 is the average pkt size used for
711 * computing cur_tp
712 */
713 tmp_mrs = &mi->r[idx].stats;
714 tmp_cur_tp = minstrel_get_tp_avg(&mi->r[idx], tmp_mrs->prob_ewma) * 10;
715 tmp_cur_tp = tmp_cur_tp * 1200 * 8 / 1024;
716
717 return tmp_cur_tp;
718}
719
720const struct rate_control_ops mac80211_minstrel = {
721 .name = "minstrel",
722 .tx_status_noskb = minstrel_tx_status,
723 .get_rate = minstrel_get_rate,
724 .rate_init = minstrel_rate_init,
725 .alloc = minstrel_alloc,
726 .free = minstrel_free,
727 .alloc_sta = minstrel_alloc_sta,
728 .free_sta = minstrel_free_sta,
729#ifdef CONFIG_MAC80211_DEBUGFS
730 .add_sta_debugfs = minstrel_add_sta_debugfs,
731 .remove_sta_debugfs = minstrel_remove_sta_debugfs,
732#endif
733 .get_expected_throughput = minstrel_get_expected_throughput,
734};
735
736int __init
737rc80211_minstrel_init(void)
738{
739 return ieee80211_rate_control_register(&mac80211_minstrel);
740}
741
742void
743rc80211_minstrel_exit(void)
744{
745 ieee80211_rate_control_unregister(&mac80211_minstrel);
746}
747
1/*
2 * Copyright (C) 2008 Felix Fietkau <nbd@openwrt.org>
3 *
4 * This program is free software; you can redistribute it and/or modify
5 * it under the terms of the GNU General Public License version 2 as
6 * published by the Free Software Foundation.
7 *
8 * Based on minstrel.c:
9 * Copyright (C) 2005-2007 Derek Smithies <derek@indranet.co.nz>
10 * Sponsored by Indranet Technologies Ltd
11 *
12 * Based on sample.c:
13 * Copyright (c) 2005 John Bicket
14 * All rights reserved.
15 *
16 * Redistribution and use in source and binary forms, with or without
17 * modification, are permitted provided that the following conditions
18 * are met:
19 * 1. Redistributions of source code must retain the above copyright
20 * notice, this list of conditions and the following disclaimer,
21 * without modification.
22 * 2. Redistributions in binary form must reproduce at minimum a disclaimer
23 * similar to the "NO WARRANTY" disclaimer below ("Disclaimer") and any
24 * redistribution must be conditioned upon including a substantially
25 * similar Disclaimer requirement for further binary redistribution.
26 * 3. Neither the names of the above-listed copyright holders nor the names
27 * of any contributors may be used to endorse or promote products derived
28 * from this software without specific prior written permission.
29 *
30 * Alternatively, this software may be distributed under the terms of the
31 * GNU General Public License ("GPL") version 2 as published by the Free
32 * Software Foundation.
33 *
34 * NO WARRANTY
35 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
36 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
37 * LIMITED TO, THE IMPLIED WARRANTIES OF NONINFRINGEMENT, MERCHANTIBILITY
38 * AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL
39 * THE COPYRIGHT HOLDERS OR CONTRIBUTORS BE LIABLE FOR SPECIAL, EXEMPLARY,
40 * OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
41 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
42 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER
43 * IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
44 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF
45 * THE POSSIBILITY OF SUCH DAMAGES.
46 */
47#include <linux/netdevice.h>
48#include <linux/types.h>
49#include <linux/skbuff.h>
50#include <linux/debugfs.h>
51#include <linux/random.h>
52#include <linux/ieee80211.h>
53#include <linux/slab.h>
54#include <net/mac80211.h>
55#include "rate.h"
56#include "rc80211_minstrel.h"
57
58#define SAMPLE_TBL(_mi, _idx, _col) \
59 _mi->sample_table[(_idx * SAMPLE_COLUMNS) + _col]
60
61/* convert mac80211 rate index to local array index */
62static inline int
63rix_to_ndx(struct minstrel_sta_info *mi, int rix)
64{
65 int i = rix;
66 for (i = rix; i >= 0; i--)
67 if (mi->r[i].rix == rix)
68 break;
69 return i;
70}
71
72/* return current EMWA throughput */
73int minstrel_get_tp_avg(struct minstrel_rate *mr, int prob_ewma)
74{
75 int usecs;
76
77 usecs = mr->perfect_tx_time;
78 if (!usecs)
79 usecs = 1000000;
80
81 /* reset thr. below 10% success */
82 if (mr->stats.prob_ewma < MINSTREL_FRAC(10, 100))
83 return 0;
84
85 if (prob_ewma > MINSTREL_FRAC(90, 100))
86 return MINSTREL_TRUNC(100000 * (MINSTREL_FRAC(90, 100) / usecs));
87 else
88 return MINSTREL_TRUNC(100000 * (prob_ewma / usecs));
89}
90
91/* find & sort topmost throughput rates */
92static inline void
93minstrel_sort_best_tp_rates(struct minstrel_sta_info *mi, int i, u8 *tp_list)
94{
95 int j;
96 struct minstrel_rate_stats *tmp_mrs;
97 struct minstrel_rate_stats *cur_mrs = &mi->r[i].stats;
98
99 for (j = MAX_THR_RATES; j > 0; --j) {
100 tmp_mrs = &mi->r[tp_list[j - 1]].stats;
101 if (minstrel_get_tp_avg(&mi->r[i], cur_mrs->prob_ewma) <=
102 minstrel_get_tp_avg(&mi->r[tp_list[j - 1]], tmp_mrs->prob_ewma))
103 break;
104 }
105
106 if (j < MAX_THR_RATES - 1)
107 memmove(&tp_list[j + 1], &tp_list[j], MAX_THR_RATES - (j + 1));
108 if (j < MAX_THR_RATES)
109 tp_list[j] = i;
110}
111
112static void
113minstrel_set_rate(struct minstrel_sta_info *mi, struct ieee80211_sta_rates *ratetbl,
114 int offset, int idx)
115{
116 struct minstrel_rate *r = &mi->r[idx];
117
118 ratetbl->rate[offset].idx = r->rix;
119 ratetbl->rate[offset].count = r->adjusted_retry_count;
120 ratetbl->rate[offset].count_cts = r->retry_count_cts;
121 ratetbl->rate[offset].count_rts = r->stats.retry_count_rtscts;
122}
123
124static void
125minstrel_update_rates(struct minstrel_priv *mp, struct minstrel_sta_info *mi)
126{
127 struct ieee80211_sta_rates *ratetbl;
128 int i = 0;
129
130 ratetbl = kzalloc(sizeof(*ratetbl), GFP_ATOMIC);
131 if (!ratetbl)
132 return;
133
134 /* Start with max_tp_rate */
135 minstrel_set_rate(mi, ratetbl, i++, mi->max_tp_rate[0]);
136
137 if (mp->hw->max_rates >= 3) {
138 /* At least 3 tx rates supported, use max_tp_rate2 next */
139 minstrel_set_rate(mi, ratetbl, i++, mi->max_tp_rate[1]);
140 }
141
142 if (mp->hw->max_rates >= 2) {
143 /* At least 2 tx rates supported, use max_prob_rate next */
144 minstrel_set_rate(mi, ratetbl, i++, mi->max_prob_rate);
145 }
146
147 /* Use lowest rate last */
148 ratetbl->rate[i].idx = mi->lowest_rix;
149 ratetbl->rate[i].count = mp->max_retry;
150 ratetbl->rate[i].count_cts = mp->max_retry;
151 ratetbl->rate[i].count_rts = mp->max_retry;
152
153 rate_control_set_rates(mp->hw, mi->sta, ratetbl);
154}
155
156/*
157* Recalculate statistics and counters of a given rate
158*/
159void
160minstrel_calc_rate_stats(struct minstrel_rate_stats *mrs)
161{
162 unsigned int cur_prob;
163
164 if (unlikely(mrs->attempts > 0)) {
165 mrs->sample_skipped = 0;
166 cur_prob = MINSTREL_FRAC(mrs->success, mrs->attempts);
167 if (unlikely(!mrs->att_hist)) {
168 mrs->prob_ewma = cur_prob;
169 } else {
170 /* update exponential weighted moving variance */
171 mrs->prob_ewmv = minstrel_ewmv(mrs->prob_ewmv,
172 cur_prob,
173 mrs->prob_ewma,
174 EWMA_LEVEL);
175
176 /*update exponential weighted moving avarage */
177 mrs->prob_ewma = minstrel_ewma(mrs->prob_ewma,
178 cur_prob,
179 EWMA_LEVEL);
180 }
181 mrs->att_hist += mrs->attempts;
182 mrs->succ_hist += mrs->success;
183 } else {
184 mrs->sample_skipped++;
185 }
186
187 mrs->last_success = mrs->success;
188 mrs->last_attempts = mrs->attempts;
189 mrs->success = 0;
190 mrs->attempts = 0;
191}
192
193static void
194minstrel_update_stats(struct minstrel_priv *mp, struct minstrel_sta_info *mi)
195{
196 u8 tmp_tp_rate[MAX_THR_RATES];
197 u8 tmp_prob_rate = 0;
198 int i, tmp_cur_tp, tmp_prob_tp;
199
200 for (i = 0; i < MAX_THR_RATES; i++)
201 tmp_tp_rate[i] = 0;
202
203 for (i = 0; i < mi->n_rates; i++) {
204 struct minstrel_rate *mr = &mi->r[i];
205 struct minstrel_rate_stats *mrs = &mi->r[i].stats;
206 struct minstrel_rate_stats *tmp_mrs = &mi->r[tmp_prob_rate].stats;
207
208 /* Update statistics of success probability per rate */
209 minstrel_calc_rate_stats(mrs);
210
211 /* Sample less often below the 10% chance of success.
212 * Sample less often above the 95% chance of success. */
213 if (mrs->prob_ewma > MINSTREL_FRAC(95, 100) ||
214 mrs->prob_ewma < MINSTREL_FRAC(10, 100)) {
215 mr->adjusted_retry_count = mrs->retry_count >> 1;
216 if (mr->adjusted_retry_count > 2)
217 mr->adjusted_retry_count = 2;
218 mr->sample_limit = 4;
219 } else {
220 mr->sample_limit = -1;
221 mr->adjusted_retry_count = mrs->retry_count;
222 }
223 if (!mr->adjusted_retry_count)
224 mr->adjusted_retry_count = 2;
225
226 minstrel_sort_best_tp_rates(mi, i, tmp_tp_rate);
227
228 /* To determine the most robust rate (max_prob_rate) used at
229 * 3rd mmr stage we distinct between two cases:
230 * (1) if any success probabilitiy >= 95%, out of those rates
231 * choose the maximum throughput rate as max_prob_rate
232 * (2) if all success probabilities < 95%, the rate with
233 * highest success probability is chosen as max_prob_rate */
234 if (mrs->prob_ewma >= MINSTREL_FRAC(95, 100)) {
235 tmp_cur_tp = minstrel_get_tp_avg(mr, mrs->prob_ewma);
236 tmp_prob_tp = minstrel_get_tp_avg(&mi->r[tmp_prob_rate],
237 tmp_mrs->prob_ewma);
238 if (tmp_cur_tp >= tmp_prob_tp)
239 tmp_prob_rate = i;
240 } else {
241 if (mrs->prob_ewma >= tmp_mrs->prob_ewma)
242 tmp_prob_rate = i;
243 }
244 }
245
246 /* Assign the new rate set */
247 memcpy(mi->max_tp_rate, tmp_tp_rate, sizeof(mi->max_tp_rate));
248 mi->max_prob_rate = tmp_prob_rate;
249
250#ifdef CONFIG_MAC80211_DEBUGFS
251 /* use fixed index if set */
252 if (mp->fixed_rate_idx != -1) {
253 mi->max_tp_rate[0] = mp->fixed_rate_idx;
254 mi->max_tp_rate[1] = mp->fixed_rate_idx;
255 mi->max_prob_rate = mp->fixed_rate_idx;
256 }
257#endif
258
259 /* Reset update timer */
260 mi->last_stats_update = jiffies;
261
262 minstrel_update_rates(mp, mi);
263}
264
265static void
266minstrel_tx_status(void *priv, struct ieee80211_supported_band *sband,
267 void *priv_sta, struct ieee80211_tx_status *st)
268{
269 struct ieee80211_tx_info *info = st->info;
270 struct minstrel_priv *mp = priv;
271 struct minstrel_sta_info *mi = priv_sta;
272 struct ieee80211_tx_rate *ar = info->status.rates;
273 int i, ndx;
274 int success;
275
276 success = !!(info->flags & IEEE80211_TX_STAT_ACK);
277
278 for (i = 0; i < IEEE80211_TX_MAX_RATES; i++) {
279 if (ar[i].idx < 0)
280 break;
281
282 ndx = rix_to_ndx(mi, ar[i].idx);
283 if (ndx < 0)
284 continue;
285
286 mi->r[ndx].stats.attempts += ar[i].count;
287
288 if ((i != IEEE80211_TX_MAX_RATES - 1) && (ar[i + 1].idx < 0))
289 mi->r[ndx].stats.success += success;
290 }
291
292 if ((info->flags & IEEE80211_TX_CTL_RATE_CTRL_PROBE) && (i >= 0))
293 mi->sample_packets++;
294
295 if (mi->sample_deferred > 0)
296 mi->sample_deferred--;
297
298 if (time_after(jiffies, mi->last_stats_update +
299 (mp->update_interval * HZ) / 1000))
300 minstrel_update_stats(mp, mi);
301}
302
303
304static inline unsigned int
305minstrel_get_retry_count(struct minstrel_rate *mr,
306 struct ieee80211_tx_info *info)
307{
308 u8 retry = mr->adjusted_retry_count;
309
310 if (info->control.use_rts)
311 retry = max_t(u8, 2, min(mr->stats.retry_count_rtscts, retry));
312 else if (info->control.use_cts_prot)
313 retry = max_t(u8, 2, min(mr->retry_count_cts, retry));
314 return retry;
315}
316
317
318static int
319minstrel_get_next_sample(struct minstrel_sta_info *mi)
320{
321 unsigned int sample_ndx;
322 sample_ndx = SAMPLE_TBL(mi, mi->sample_row, mi->sample_column);
323 mi->sample_row++;
324 if ((int) mi->sample_row >= mi->n_rates) {
325 mi->sample_row = 0;
326 mi->sample_column++;
327 if (mi->sample_column >= SAMPLE_COLUMNS)
328 mi->sample_column = 0;
329 }
330 return sample_ndx;
331}
332
333static void
334minstrel_get_rate(void *priv, struct ieee80211_sta *sta,
335 void *priv_sta, struct ieee80211_tx_rate_control *txrc)
336{
337 struct sk_buff *skb = txrc->skb;
338 struct ieee80211_tx_info *info = IEEE80211_SKB_CB(skb);
339 struct minstrel_sta_info *mi = priv_sta;
340 struct minstrel_priv *mp = priv;
341 struct ieee80211_tx_rate *rate = &info->control.rates[0];
342 struct minstrel_rate *msr, *mr;
343 unsigned int ndx;
344 bool mrr_capable;
345 bool prev_sample;
346 int delta;
347 int sampling_ratio;
348
349 /* management/no-ack frames do not use rate control */
350 if (rate_control_send_low(sta, priv_sta, txrc))
351 return;
352
353 /* check multi-rate-retry capabilities & adjust lookaround_rate */
354 mrr_capable = mp->has_mrr &&
355 !txrc->rts &&
356 !txrc->bss_conf->use_cts_prot;
357 if (mrr_capable)
358 sampling_ratio = mp->lookaround_rate_mrr;
359 else
360 sampling_ratio = mp->lookaround_rate;
361
362 /* increase sum packet counter */
363 mi->total_packets++;
364
365#ifdef CONFIG_MAC80211_DEBUGFS
366 if (mp->fixed_rate_idx != -1)
367 return;
368#endif
369
370 /* Don't use EAPOL frames for sampling on non-mrr hw */
371 if (mp->hw->max_rates == 1 &&
372 (info->control.flags & IEEE80211_TX_CTRL_PORT_CTRL_PROTO))
373 return;
374
375 delta = (mi->total_packets * sampling_ratio / 100) -
376 (mi->sample_packets + mi->sample_deferred / 2);
377
378 /* delta < 0: no sampling required */
379 prev_sample = mi->prev_sample;
380 mi->prev_sample = false;
381 if (delta < 0 || (!mrr_capable && prev_sample))
382 return;
383
384 if (mi->total_packets >= 10000) {
385 mi->sample_deferred = 0;
386 mi->sample_packets = 0;
387 mi->total_packets = 0;
388 } else if (delta > mi->n_rates * 2) {
389 /* With multi-rate retry, not every planned sample
390 * attempt actually gets used, due to the way the retry
391 * chain is set up - [max_tp,sample,prob,lowest] for
392 * sample_rate < max_tp.
393 *
394 * If there's too much sampling backlog and the link
395 * starts getting worse, minstrel would start bursting
396 * out lots of sampling frames, which would result
397 * in a large throughput loss. */
398 mi->sample_packets += (delta - mi->n_rates * 2);
399 }
400
401 /* get next random rate sample */
402 ndx = minstrel_get_next_sample(mi);
403 msr = &mi->r[ndx];
404 mr = &mi->r[mi->max_tp_rate[0]];
405
406 /* Decide if direct ( 1st mrr stage) or indirect (2nd mrr stage)
407 * rate sampling method should be used.
408 * Respect such rates that are not sampled for 20 interations.
409 */
410 if (mrr_capable &&
411 msr->perfect_tx_time > mr->perfect_tx_time &&
412 msr->stats.sample_skipped < 20) {
413 /* Only use IEEE80211_TX_CTL_RATE_CTRL_PROBE to mark
414 * packets that have the sampling rate deferred to the
415 * second MRR stage. Increase the sample counter only
416 * if the deferred sample rate was actually used.
417 * Use the sample_deferred counter to make sure that
418 * the sampling is not done in large bursts */
419 info->flags |= IEEE80211_TX_CTL_RATE_CTRL_PROBE;
420 rate++;
421 mi->sample_deferred++;
422 } else {
423 if (!msr->sample_limit)
424 return;
425
426 mi->sample_packets++;
427 if (msr->sample_limit > 0)
428 msr->sample_limit--;
429 }
430
431 /* If we're not using MRR and the sampling rate already
432 * has a probability of >95%, we shouldn't be attempting
433 * to use it, as this only wastes precious airtime */
434 if (!mrr_capable &&
435 (mi->r[ndx].stats.prob_ewma > MINSTREL_FRAC(95, 100)))
436 return;
437
438 mi->prev_sample = true;
439
440 rate->idx = mi->r[ndx].rix;
441 rate->count = minstrel_get_retry_count(&mi->r[ndx], info);
442}
443
444
445static void
446calc_rate_durations(enum nl80211_band band,
447 struct minstrel_rate *d,
448 struct ieee80211_rate *rate,
449 struct cfg80211_chan_def *chandef)
450{
451 int erp = !!(rate->flags & IEEE80211_RATE_ERP_G);
452 int shift = ieee80211_chandef_get_shift(chandef);
453
454 d->perfect_tx_time = ieee80211_frame_duration(band, 1200,
455 DIV_ROUND_UP(rate->bitrate, 1 << shift), erp, 1,
456 shift);
457 d->ack_time = ieee80211_frame_duration(band, 10,
458 DIV_ROUND_UP(rate->bitrate, 1 << shift), erp, 1,
459 shift);
460}
461
462static void
463init_sample_table(struct minstrel_sta_info *mi)
464{
465 unsigned int i, col, new_idx;
466 u8 rnd[8];
467
468 mi->sample_column = 0;
469 mi->sample_row = 0;
470 memset(mi->sample_table, 0xff, SAMPLE_COLUMNS * mi->n_rates);
471
472 for (col = 0; col < SAMPLE_COLUMNS; col++) {
473 prandom_bytes(rnd, sizeof(rnd));
474 for (i = 0; i < mi->n_rates; i++) {
475 new_idx = (i + rnd[i & 7]) % mi->n_rates;
476 while (SAMPLE_TBL(mi, new_idx, col) != 0xff)
477 new_idx = (new_idx + 1) % mi->n_rates;
478
479 SAMPLE_TBL(mi, new_idx, col) = i;
480 }
481 }
482}
483
484static void
485minstrel_rate_init(void *priv, struct ieee80211_supported_band *sband,
486 struct cfg80211_chan_def *chandef,
487 struct ieee80211_sta *sta, void *priv_sta)
488{
489 struct minstrel_sta_info *mi = priv_sta;
490 struct minstrel_priv *mp = priv;
491 struct ieee80211_rate *ctl_rate;
492 unsigned int i, n = 0;
493 unsigned int t_slot = 9; /* FIXME: get real slot time */
494 u32 rate_flags;
495
496 mi->sta = sta;
497 mi->lowest_rix = rate_lowest_index(sband, sta);
498 ctl_rate = &sband->bitrates[mi->lowest_rix];
499 mi->sp_ack_dur = ieee80211_frame_duration(sband->band, 10,
500 ctl_rate->bitrate,
501 !!(ctl_rate->flags & IEEE80211_RATE_ERP_G), 1,
502 ieee80211_chandef_get_shift(chandef));
503
504 rate_flags = ieee80211_chandef_rate_flags(&mp->hw->conf.chandef);
505 memset(mi->max_tp_rate, 0, sizeof(mi->max_tp_rate));
506 mi->max_prob_rate = 0;
507
508 for (i = 0; i < sband->n_bitrates; i++) {
509 struct minstrel_rate *mr = &mi->r[n];
510 struct minstrel_rate_stats *mrs = &mi->r[n].stats;
511 unsigned int tx_time = 0, tx_time_cts = 0, tx_time_rtscts = 0;
512 unsigned int tx_time_single;
513 unsigned int cw = mp->cw_min;
514 int shift;
515
516 if (!rate_supported(sta, sband->band, i))
517 continue;
518 if ((rate_flags & sband->bitrates[i].flags) != rate_flags)
519 continue;
520
521 n++;
522 memset(mr, 0, sizeof(*mr));
523 memset(mrs, 0, sizeof(*mrs));
524
525 mr->rix = i;
526 shift = ieee80211_chandef_get_shift(chandef);
527 mr->bitrate = DIV_ROUND_UP(sband->bitrates[i].bitrate,
528 (1 << shift) * 5);
529 calc_rate_durations(sband->band, mr, &sband->bitrates[i],
530 chandef);
531
532 /* calculate maximum number of retransmissions before
533 * fallback (based on maximum segment size) */
534 mr->sample_limit = -1;
535 mrs->retry_count = 1;
536 mr->retry_count_cts = 1;
537 mrs->retry_count_rtscts = 1;
538 tx_time = mr->perfect_tx_time + mi->sp_ack_dur;
539 do {
540 /* add one retransmission */
541 tx_time_single = mr->ack_time + mr->perfect_tx_time;
542
543 /* contention window */
544 tx_time_single += (t_slot * cw) >> 1;
545 cw = min((cw << 1) | 1, mp->cw_max);
546
547 tx_time += tx_time_single;
548 tx_time_cts += tx_time_single + mi->sp_ack_dur;
549 tx_time_rtscts += tx_time_single + 2 * mi->sp_ack_dur;
550 if ((tx_time_cts < mp->segment_size) &&
551 (mr->retry_count_cts < mp->max_retry))
552 mr->retry_count_cts++;
553 if ((tx_time_rtscts < mp->segment_size) &&
554 (mrs->retry_count_rtscts < mp->max_retry))
555 mrs->retry_count_rtscts++;
556 } while ((tx_time < mp->segment_size) &&
557 (++mr->stats.retry_count < mp->max_retry));
558 mr->adjusted_retry_count = mrs->retry_count;
559 if (!(sband->bitrates[i].flags & IEEE80211_RATE_ERP_G))
560 mr->retry_count_cts = mrs->retry_count;
561 }
562
563 for (i = n; i < sband->n_bitrates; i++) {
564 struct minstrel_rate *mr = &mi->r[i];
565 mr->rix = -1;
566 }
567
568 mi->n_rates = n;
569 mi->last_stats_update = jiffies;
570
571 init_sample_table(mi);
572 minstrel_update_rates(mp, mi);
573}
574
575static void *
576minstrel_alloc_sta(void *priv, struct ieee80211_sta *sta, gfp_t gfp)
577{
578 struct ieee80211_supported_band *sband;
579 struct minstrel_sta_info *mi;
580 struct minstrel_priv *mp = priv;
581 struct ieee80211_hw *hw = mp->hw;
582 int max_rates = 0;
583 int i;
584
585 mi = kzalloc(sizeof(struct minstrel_sta_info), gfp);
586 if (!mi)
587 return NULL;
588
589 for (i = 0; i < NUM_NL80211_BANDS; i++) {
590 sband = hw->wiphy->bands[i];
591 if (sband && sband->n_bitrates > max_rates)
592 max_rates = sband->n_bitrates;
593 }
594
595 mi->r = kzalloc(sizeof(struct minstrel_rate) * max_rates, gfp);
596 if (!mi->r)
597 goto error;
598
599 mi->sample_table = kmalloc(SAMPLE_COLUMNS * max_rates, gfp);
600 if (!mi->sample_table)
601 goto error1;
602
603 mi->last_stats_update = jiffies;
604 return mi;
605
606error1:
607 kfree(mi->r);
608error:
609 kfree(mi);
610 return NULL;
611}
612
613static void
614minstrel_free_sta(void *priv, struct ieee80211_sta *sta, void *priv_sta)
615{
616 struct minstrel_sta_info *mi = priv_sta;
617
618 kfree(mi->sample_table);
619 kfree(mi->r);
620 kfree(mi);
621}
622
623static void
624minstrel_init_cck_rates(struct minstrel_priv *mp)
625{
626 static const int bitrates[4] = { 10, 20, 55, 110 };
627 struct ieee80211_supported_band *sband;
628 u32 rate_flags = ieee80211_chandef_rate_flags(&mp->hw->conf.chandef);
629 int i, j;
630
631 sband = mp->hw->wiphy->bands[NL80211_BAND_2GHZ];
632 if (!sband)
633 return;
634
635 for (i = 0, j = 0; i < sband->n_bitrates; i++) {
636 struct ieee80211_rate *rate = &sband->bitrates[i];
637
638 if (rate->flags & IEEE80211_RATE_ERP_G)
639 continue;
640
641 if ((rate_flags & sband->bitrates[i].flags) != rate_flags)
642 continue;
643
644 for (j = 0; j < ARRAY_SIZE(bitrates); j++) {
645 if (rate->bitrate != bitrates[j])
646 continue;
647
648 mp->cck_rates[j] = i;
649 break;
650 }
651 }
652}
653
654static void *
655minstrel_alloc(struct ieee80211_hw *hw, struct dentry *debugfsdir)
656{
657 struct minstrel_priv *mp;
658
659 mp = kzalloc(sizeof(struct minstrel_priv), GFP_ATOMIC);
660 if (!mp)
661 return NULL;
662
663 /* contention window settings
664 * Just an approximation. Using the per-queue values would complicate
665 * the calculations and is probably unnecessary */
666 mp->cw_min = 15;
667 mp->cw_max = 1023;
668
669 /* number of packets (in %) to use for sampling other rates
670 * sample less often for non-mrr packets, because the overhead
671 * is much higher than with mrr */
672 mp->lookaround_rate = 5;
673 mp->lookaround_rate_mrr = 10;
674
675 /* maximum time that the hw is allowed to stay in one MRR segment */
676 mp->segment_size = 6000;
677
678 if (hw->max_rate_tries > 0)
679 mp->max_retry = hw->max_rate_tries;
680 else
681 /* safe default, does not necessarily have to match hw properties */
682 mp->max_retry = 7;
683
684 if (hw->max_rates >= 4)
685 mp->has_mrr = true;
686
687 mp->hw = hw;
688 mp->update_interval = 100;
689
690#ifdef CONFIG_MAC80211_DEBUGFS
691 mp->fixed_rate_idx = (u32) -1;
692 mp->dbg_fixed_rate = debugfs_create_u32("fixed_rate_idx",
693 0666, debugfsdir, &mp->fixed_rate_idx);
694#endif
695
696 minstrel_init_cck_rates(mp);
697
698 return mp;
699}
700
701static void
702minstrel_free(void *priv)
703{
704#ifdef CONFIG_MAC80211_DEBUGFS
705 debugfs_remove(((struct minstrel_priv *)priv)->dbg_fixed_rate);
706#endif
707 kfree(priv);
708}
709
710static u32 minstrel_get_expected_throughput(void *priv_sta)
711{
712 struct minstrel_sta_info *mi = priv_sta;
713 struct minstrel_rate_stats *tmp_mrs;
714 int idx = mi->max_tp_rate[0];
715 int tmp_cur_tp;
716
717 /* convert pkt per sec in kbps (1200 is the average pkt size used for
718 * computing cur_tp
719 */
720 tmp_mrs = &mi->r[idx].stats;
721 tmp_cur_tp = minstrel_get_tp_avg(&mi->r[idx], tmp_mrs->prob_ewma) * 10;
722 tmp_cur_tp = tmp_cur_tp * 1200 * 8 / 1024;
723
724 return tmp_cur_tp;
725}
726
727const struct rate_control_ops mac80211_minstrel = {
728 .name = "minstrel",
729 .tx_status_ext = minstrel_tx_status,
730 .get_rate = minstrel_get_rate,
731 .rate_init = minstrel_rate_init,
732 .alloc = minstrel_alloc,
733 .free = minstrel_free,
734 .alloc_sta = minstrel_alloc_sta,
735 .free_sta = minstrel_free_sta,
736#ifdef CONFIG_MAC80211_DEBUGFS
737 .add_sta_debugfs = minstrel_add_sta_debugfs,
738 .remove_sta_debugfs = minstrel_remove_sta_debugfs,
739#endif
740 .get_expected_throughput = minstrel_get_expected_throughput,
741};
742
743int __init
744rc80211_minstrel_init(void)
745{
746 return ieee80211_rate_control_register(&mac80211_minstrel);
747}
748
749void
750rc80211_minstrel_exit(void)
751{
752 ieee80211_rate_control_unregister(&mac80211_minstrel);
753}
754