xref: /openbmc/linux/net/mac80211/rate.c (revision d0b73b48) 
1 /*
2  * Copyright 2002-2005, Instant802 Networks, Inc.
3  * Copyright 2005-2006, Devicescape Software, Inc.
4  * Copyright (c) 2006 Jiri Benc <jbenc@suse.cz>
5  *
6  * This program is free software; you can redistribute it and/or modify
7  * it under the terms of the GNU General Public License version 2 as
8  * published by the Free Software Foundation.
9  */
10 
11 #include <linux/kernel.h>
12 #include <linux/rtnetlink.h>
13 #include <linux/slab.h>
14 #include <linux/module.h>
15 #include "rate.h"
16 #include "ieee80211_i.h"
17 #include "debugfs.h"
18 
19 struct rate_control_alg {
20 	struct list_head list;
21 	struct rate_control_ops *ops;
22 };
23 
24 static LIST_HEAD(rate_ctrl_algs);
25 static DEFINE_MUTEX(rate_ctrl_mutex);
26 
27 static char *ieee80211_default_rc_algo = CONFIG_MAC80211_RC_DEFAULT;
28 module_param(ieee80211_default_rc_algo, charp, 0644);
29 MODULE_PARM_DESC(ieee80211_default_rc_algo,
30 		 "Default rate control algorithm for mac80211 to use");
31 
32 int ieee80211_rate_control_register(struct rate_control_ops *ops)
33 {
34 	struct rate_control_alg *alg;
35 
36 	if (!ops->name)
37 		return -EINVAL;
38 
39 	mutex_lock(&rate_ctrl_mutex);
40 	list_for_each_entry(alg, &rate_ctrl_algs, list) {
41 		if (!strcmp(alg->ops->name, ops->name)) {
42 			/* don't register an algorithm twice */
43 			WARN_ON(1);
44 			mutex_unlock(&rate_ctrl_mutex);
45 			return -EALREADY;
46 		}
47 	}
48 
49 	alg = kzalloc(sizeof(*alg), GFP_KERNEL);
50 	if (alg == NULL) {
51 		mutex_unlock(&rate_ctrl_mutex);
52 		return -ENOMEM;
53 	}
54 	alg->ops = ops;
55 
56 	list_add_tail(&alg->list, &rate_ctrl_algs);
57 	mutex_unlock(&rate_ctrl_mutex);
58 
59 	return 0;
60 }
61 EXPORT_SYMBOL(ieee80211_rate_control_register);
62 
63 void ieee80211_rate_control_unregister(struct rate_control_ops *ops)
64 {
65 	struct rate_control_alg *alg;
66 
67 	mutex_lock(&rate_ctrl_mutex);
68 	list_for_each_entry(alg, &rate_ctrl_algs, list) {
69 		if (alg->ops == ops) {
70 			list_del(&alg->list);
71 			kfree(alg);
72 			break;
73 		}
74 	}
75 	mutex_unlock(&rate_ctrl_mutex);
76 }
77 EXPORT_SYMBOL(ieee80211_rate_control_unregister);
78 
79 static struct rate_control_ops *
80 ieee80211_try_rate_control_ops_get(const char *name)
81 {
82 	struct rate_control_alg *alg;
83 	struct rate_control_ops *ops = NULL;
84 
85 	if (!name)
86 		return NULL;
87 
88 	mutex_lock(&rate_ctrl_mutex);
89 	list_for_each_entry(alg, &rate_ctrl_algs, list) {
90 		if (!strcmp(alg->ops->name, name))
91 			if (try_module_get(alg->ops->module)) {
92 				ops = alg->ops;
93 				break;
94 			}
95 	}
96 	mutex_unlock(&rate_ctrl_mutex);
97 	return ops;
98 }
99 
100 /* Get the rate control algorithm. */
101 static struct rate_control_ops *
102 ieee80211_rate_control_ops_get(const char *name)
103 {
104 	struct rate_control_ops *ops;
105 	const char *alg_name;
106 
107 	kparam_block_sysfs_write(ieee80211_default_rc_algo);
108 	if (!name)
109 		alg_name = ieee80211_default_rc_algo;
110 	else
111 		alg_name = name;
112 
113 	ops = ieee80211_try_rate_control_ops_get(alg_name);
114 	if (!ops) {
115 		request_module("rc80211_%s", alg_name);
116 		ops = ieee80211_try_rate_control_ops_get(alg_name);
117 	}
118 	if (!ops && name)
119 		/* try default if specific alg requested but not found */
120 		ops = ieee80211_try_rate_control_ops_get(ieee80211_default_rc_algo);
121 
122 	/* try built-in one if specific alg requested but not found */
123 	if (!ops && strlen(CONFIG_MAC80211_RC_DEFAULT))
124 		ops = ieee80211_try_rate_control_ops_get(CONFIG_MAC80211_RC_DEFAULT);
125 	kparam_unblock_sysfs_write(ieee80211_default_rc_algo);
126 
127 	return ops;
128 }
129 
130 static void ieee80211_rate_control_ops_put(struct rate_control_ops *ops)
131 {
132 	module_put(ops->module);
133 }
134 
135 #ifdef CONFIG_MAC80211_DEBUGFS
136 static ssize_t rcname_read(struct file *file, char __user *userbuf,
137 			   size_t count, loff_t *ppos)
138 {
139 	struct rate_control_ref *ref = file->private_data;
140 	int len = strlen(ref->ops->name);
141 
142 	return simple_read_from_buffer(userbuf, count, ppos,
143 				       ref->ops->name, len);
144 }
145 
146 static const struct file_operations rcname_ops = {
147 	.read = rcname_read,
148 	.open = simple_open,
149 	.llseek = default_llseek,
150 };
151 #endif
152 
153 static struct rate_control_ref *rate_control_alloc(const char *name,
154 					    struct ieee80211_local *local)
155 {
156 	struct dentry *debugfsdir = NULL;
157 	struct rate_control_ref *ref;
158 
159 	ref = kmalloc(sizeof(struct rate_control_ref), GFP_KERNEL);
160 	if (!ref)
161 		goto fail_ref;
162 	ref->local = local;
163 	ref->ops = ieee80211_rate_control_ops_get(name);
164 	if (!ref->ops)
165 		goto fail_ops;
166 
167 #ifdef CONFIG_MAC80211_DEBUGFS
168 	debugfsdir = debugfs_create_dir("rc", local->hw.wiphy->debugfsdir);
169 	local->debugfs.rcdir = debugfsdir;
170 	debugfs_create_file("name", 0400, debugfsdir, ref, &rcname_ops);
171 #endif
172 
173 	ref->priv = ref->ops->alloc(&local->hw, debugfsdir);
174 	if (!ref->priv)
175 		goto fail_priv;
176 	return ref;
177 
178 fail_priv:
179 	ieee80211_rate_control_ops_put(ref->ops);
180 fail_ops:
181 	kfree(ref);
182 fail_ref:
183 	return NULL;
184 }
185 
186 static void rate_control_free(struct rate_control_ref *ctrl_ref)
187 {
188 	ctrl_ref->ops->free(ctrl_ref->priv);
189 
190 #ifdef CONFIG_MAC80211_DEBUGFS
191 	debugfs_remove_recursive(ctrl_ref->local->debugfs.rcdir);
192 	ctrl_ref->local->debugfs.rcdir = NULL;
193 #endif
194 
195 	ieee80211_rate_control_ops_put(ctrl_ref->ops);
196 	kfree(ctrl_ref);
197 }
198 
199 static bool rc_no_data_or_no_ack_use_min(struct ieee80211_tx_rate_control *txrc)
200 {
201 	struct sk_buff *skb = txrc->skb;
202 	struct ieee80211_hdr *hdr = (struct ieee80211_hdr *) skb->data;
203 	struct ieee80211_tx_info *info = IEEE80211_SKB_CB(skb);
204 	__le16 fc;
205 
206 	fc = hdr->frame_control;
207 
208 	return (info->flags & (IEEE80211_TX_CTL_NO_ACK |
209 			       IEEE80211_TX_CTL_USE_MINRATE)) ||
210 		!ieee80211_is_data(fc);
211 }
212 
213 static void rc_send_low_broadcast(s8 *idx, u32 basic_rates,
214 				  struct ieee80211_supported_band *sband)
215 {
216 	u8 i;
217 
218 	if (basic_rates == 0)
219 		return; /* assume basic rates unknown and accept rate */
220 	if (*idx < 0)
221 		return;
222 	if (basic_rates & (1 << *idx))
223 		return; /* selected rate is a basic rate */
224 
225 	for (i = *idx + 1; i <= sband->n_bitrates; i++) {
226 		if (basic_rates & (1 << i)) {
227 			*idx = i;
228 			return;
229 		}
230 	}
231 
232 	/* could not find a basic rate; use original selection */
233 }
234 
235 static inline s8
236 rate_lowest_non_cck_index(struct ieee80211_supported_band *sband,
237 			  struct ieee80211_sta *sta)
238 {
239 	int i;
240 
241 	for (i = 0; i < sband->n_bitrates; i++) {
242 		struct ieee80211_rate *srate = &sband->bitrates[i];
243 		if ((srate->bitrate == 10) || (srate->bitrate == 20) ||
244 		    (srate->bitrate == 55) || (srate->bitrate == 110))
245 			continue;
246 
247 		if (rate_supported(sta, sband->band, i))
248 			return i;
249 	}
250 
251 	/* No matching rate found */
252 	return 0;
253 }
254 
255 
256 bool rate_control_send_low(struct ieee80211_sta *sta,
257 			   void *priv_sta,
258 			   struct ieee80211_tx_rate_control *txrc)
259 {
260 	struct ieee80211_tx_info *info = IEEE80211_SKB_CB(txrc->skb);
261 	struct ieee80211_supported_band *sband = txrc->sband;
262 	int mcast_rate;
263 
264 	if (!sta || !priv_sta || rc_no_data_or_no_ack_use_min(txrc)) {
265 		if ((sband->band != IEEE80211_BAND_2GHZ) ||
266 		    !(info->flags & IEEE80211_TX_CTL_NO_CCK_RATE))
267 			info->control.rates[0].idx =
268 				rate_lowest_index(txrc->sband, sta);
269 		else
270 			info->control.rates[0].idx =
271 				rate_lowest_non_cck_index(txrc->sband, sta);
272 		info->control.rates[0].count =
273 			(info->flags & IEEE80211_TX_CTL_NO_ACK) ?
274 			1 : txrc->hw->max_rate_tries;
275 		if (!sta && txrc->bss) {
276 			mcast_rate = txrc->bss_conf->mcast_rate[sband->band];
277 			if (mcast_rate > 0) {
278 				info->control.rates[0].idx = mcast_rate - 1;
279 				return true;
280 			}
281 
282 			rc_send_low_broadcast(&info->control.rates[0].idx,
283 					      txrc->bss_conf->basic_rates,
284 					      sband);
285 		}
286 		return true;
287 	}
288 	return false;
289 }
290 EXPORT_SYMBOL(rate_control_send_low);
291 
292 static bool rate_idx_match_legacy_mask(struct ieee80211_tx_rate *rate,
293 				       int n_bitrates, u32 mask)
294 {
295 	int j;
296 
297 	/* See whether the selected rate or anything below it is allowed. */
298 	for (j = rate->idx; j >= 0; j--) {
299 		if (mask & (1 << j)) {
300 			/* Okay, found a suitable rate. Use it. */
301 			rate->idx = j;
302 			return true;
303 		}
304 	}
305 
306 	/* Try to find a higher rate that would be allowed */
307 	for (j = rate->idx + 1; j < n_bitrates; j++) {
308 		if (mask & (1 << j)) {
309 			/* Okay, found a suitable rate. Use it. */
310 			rate->idx = j;
311 			return true;
312 		}
313 	}
314 	return false;
315 }
316 
317 static bool rate_idx_match_mcs_mask(struct ieee80211_tx_rate *rate,
318 				    u8 mcs_mask[IEEE80211_HT_MCS_MASK_LEN])
319 {
320 	int i, j;
321 	int ridx, rbit;
322 
323 	ridx = rate->idx / 8;
324 	rbit = rate->idx % 8;
325 
326 	/* sanity check */
327 	if (ridx < 0 || ridx >= IEEE80211_HT_MCS_MASK_LEN)
328 		return false;
329 
330 	/* See whether the selected rate or anything below it is allowed. */
331 	for (i = ridx; i >= 0; i--) {
332 		for (j = rbit; j >= 0; j--)
333 			if (mcs_mask[i] & BIT(j)) {
334 				rate->idx = i * 8 + j;
335 				return true;
336 			}
337 		rbit = 7;
338 	}
339 
340 	/* Try to find a higher rate that would be allowed */
341 	ridx = (rate->idx + 1) / 8;
342 	rbit = (rate->idx + 1) % 8;
343 
344 	for (i = ridx; i < IEEE80211_HT_MCS_MASK_LEN; i++) {
345 		for (j = rbit; j < 8; j++)
346 			if (mcs_mask[i] & BIT(j)) {
347 				rate->idx = i * 8 + j;
348 				return true;
349 			}
350 		rbit = 0;
351 	}
352 	return false;
353 }
354 
355 
356 
357 static void rate_idx_match_mask(struct ieee80211_tx_rate *rate,
358 				struct ieee80211_tx_rate_control *txrc,
359 				u32 mask,
360 				u8 mcs_mask[IEEE80211_HT_MCS_MASK_LEN])
361 {
362 	struct ieee80211_tx_rate alt_rate;
363 
364 	/* handle HT rates */
365 	if (rate->flags & IEEE80211_TX_RC_MCS) {
366 		if (rate_idx_match_mcs_mask(rate, mcs_mask))
367 			return;
368 
369 		/* also try the legacy rates. */
370 		alt_rate.idx = 0;
371 		/* keep protection flags */
372 		alt_rate.flags = rate->flags &
373 				 (IEEE80211_TX_RC_USE_RTS_CTS |
374 				  IEEE80211_TX_RC_USE_CTS_PROTECT |
375 				  IEEE80211_TX_RC_USE_SHORT_PREAMBLE);
376 		alt_rate.count = rate->count;
377 		if (rate_idx_match_legacy_mask(&alt_rate,
378 					       txrc->sband->n_bitrates,
379 					       mask)) {
380 			*rate = alt_rate;
381 			return;
382 		}
383 	} else {
384 		struct sk_buff *skb = txrc->skb;
385 		struct ieee80211_hdr *hdr = (struct ieee80211_hdr *) skb->data;
386 		__le16 fc;
387 
388 		/* handle legacy rates */
389 		if (rate_idx_match_legacy_mask(rate, txrc->sband->n_bitrates,
390 					       mask))
391 			return;
392 
393 		/* if HT BSS, and we handle a data frame, also try HT rates */
394 		if (txrc->bss_conf->chandef.width == NL80211_CHAN_WIDTH_20_NOHT)
395 			return;
396 
397 		fc = hdr->frame_control;
398 		if (!ieee80211_is_data(fc))
399 			return;
400 
401 		alt_rate.idx = 0;
402 		/* keep protection flags */
403 		alt_rate.flags = rate->flags &
404 				 (IEEE80211_TX_RC_USE_RTS_CTS |
405 				  IEEE80211_TX_RC_USE_CTS_PROTECT |
406 				  IEEE80211_TX_RC_USE_SHORT_PREAMBLE);
407 		alt_rate.count = rate->count;
408 
409 		alt_rate.flags |= IEEE80211_TX_RC_MCS;
410 
411 		if (txrc->bss_conf->chandef.width == NL80211_CHAN_WIDTH_40)
412 			alt_rate.flags |= IEEE80211_TX_RC_40_MHZ_WIDTH;
413 
414 		if (rate_idx_match_mcs_mask(&alt_rate, mcs_mask)) {
415 			*rate = alt_rate;
416 			return;
417 		}
418 	}
419 
420 	/*
421 	 * Uh.. No suitable rate exists. This should not really happen with
422 	 * sane TX rate mask configurations. However, should someone manage to
423 	 * configure supported rates and TX rate mask in incompatible way,
424 	 * allow the frame to be transmitted with whatever the rate control
425 	 * selected.
426 	 */
427 }
428 
429 void rate_control_get_rate(struct ieee80211_sub_if_data *sdata,
430 			   struct sta_info *sta,
431 			   struct ieee80211_tx_rate_control *txrc)
432 {
433 	struct rate_control_ref *ref = sdata->local->rate_ctrl;
434 	void *priv_sta = NULL;
435 	struct ieee80211_sta *ista = NULL;
436 	struct ieee80211_tx_info *info = IEEE80211_SKB_CB(txrc->skb);
437 	int i;
438 	u32 mask;
439 	u8 mcs_mask[IEEE80211_HT_MCS_MASK_LEN];
440 
441 	if (sta && test_sta_flag(sta, WLAN_STA_RATE_CONTROL)) {
442 		ista = &sta->sta;
443 		priv_sta = sta->rate_ctrl_priv;
444 	}
445 
446 	for (i = 0; i < IEEE80211_TX_MAX_RATES; i++) {
447 		info->control.rates[i].idx = -1;
448 		info->control.rates[i].flags = 0;
449 		info->control.rates[i].count = 0;
450 	}
451 
452 	if (sdata->local->hw.flags & IEEE80211_HW_HAS_RATE_CONTROL)
453 		return;
454 
455 	ref->ops->get_rate(ref->priv, ista, priv_sta, txrc);
456 
457 	/*
458 	 * Try to enforce the rateidx mask the user wanted. skip this if the
459 	 * default mask (allow all rates) is used to save some processing for
460 	 * the common case.
461 	 */
462 	mask = sdata->rc_rateidx_mask[info->band];
463 	memcpy(mcs_mask, sdata->rc_rateidx_mcs_mask[info->band],
464 	       sizeof(mcs_mask));
465 	if (mask != (1 << txrc->sband->n_bitrates) - 1) {
466 		if (sta) {
467 			/* Filter out rates that the STA does not support */
468 			mask &= sta->sta.supp_rates[info->band];
469 			for (i = 0; i < sizeof(mcs_mask); i++)
470 				mcs_mask[i] &= sta->sta.ht_cap.mcs.rx_mask[i];
471 		}
472 		/*
473 		 * Make sure the rate index selected for each TX rate is
474 		 * included in the configured mask and change the rate indexes
475 		 * if needed.
476 		 */
477 		for (i = 0; i < IEEE80211_TX_MAX_RATES; i++) {
478 			/* Skip invalid rates */
479 			if (info->control.rates[i].idx < 0)
480 				break;
481 			rate_idx_match_mask(&info->control.rates[i], txrc,
482 					    mask, mcs_mask);
483 		}
484 	}
485 
486 	BUG_ON(info->control.rates[0].idx < 0);
487 }
488 
489 int ieee80211_init_rate_ctrl_alg(struct ieee80211_local *local,
490 				 const char *name)
491 {
492 	struct rate_control_ref *ref;
493 
494 	ASSERT_RTNL();
495 
496 	if (local->open_count)
497 		return -EBUSY;
498 
499 	if (local->hw.flags & IEEE80211_HW_HAS_RATE_CONTROL) {
500 		if (WARN_ON(!local->ops->set_rts_threshold))
501 			return -EINVAL;
502 		return 0;
503 	}
504 
505 	ref = rate_control_alloc(name, local);
506 	if (!ref) {
507 		wiphy_warn(local->hw.wiphy,
508 			   "Failed to select rate control algorithm\n");
509 		return -ENOENT;
510 	}
511 
512 	WARN_ON(local->rate_ctrl);
513 	local->rate_ctrl = ref;
514 
515 	wiphy_debug(local->hw.wiphy, "Selected rate control algorithm '%s'\n",
516 		    ref->ops->name);
517 
518 	return 0;
519 }
520 
521 void rate_control_deinitialize(struct ieee80211_local *local)
522 {
523 	struct rate_control_ref *ref;
524 
525 	ref = local->rate_ctrl;
526 
527 	if (!ref)
528 		return;
529 
530 	local->rate_ctrl = NULL;
531 	rate_control_free(ref);
532 }
533 
534