xref: /linux/net/mac80211/ht.c (revision c0c914eca7f251c70facc37dfebeaf176601918d)
1 /*
2  * HT handling
3  *
4  * Copyright 2003, Jouni Malinen <jkmaline@cc.hut.fi>
5  * Copyright 2002-2005, Instant802 Networks, Inc.
6  * Copyright 2005-2006, Devicescape Software, Inc.
7  * Copyright 2006-2007	Jiri Benc <jbenc@suse.cz>
8  * Copyright 2007, Michael Wu <flamingice@sourmilk.net>
9  * Copyright 2007-2010, Intel Corporation
10  *
11  * This program is free software; you can redistribute it and/or modify
12  * it under the terms of the GNU General Public License version 2 as
13  * published by the Free Software Foundation.
14  */
15 
16 #include <linux/ieee80211.h>
17 #include <linux/export.h>
18 #include <net/mac80211.h>
19 #include "ieee80211_i.h"
20 #include "rate.h"
21 
22 static void __check_htcap_disable(struct ieee80211_ht_cap *ht_capa,
23 				  struct ieee80211_ht_cap *ht_capa_mask,
24 				  struct ieee80211_sta_ht_cap *ht_cap,
25 				  u16 flag)
26 {
27 	__le16 le_flag = cpu_to_le16(flag);
28 	if (ht_capa_mask->cap_info & le_flag) {
29 		if (!(ht_capa->cap_info & le_flag))
30 			ht_cap->cap &= ~flag;
31 	}
32 }
33 
34 static void __check_htcap_enable(struct ieee80211_ht_cap *ht_capa,
35 				  struct ieee80211_ht_cap *ht_capa_mask,
36 				  struct ieee80211_sta_ht_cap *ht_cap,
37 				  u16 flag)
38 {
39 	__le16 le_flag = cpu_to_le16(flag);
40 
41 	if ((ht_capa_mask->cap_info & le_flag) &&
42 	    (ht_capa->cap_info & le_flag))
43 		ht_cap->cap |= flag;
44 }
45 
46 void ieee80211_apply_htcap_overrides(struct ieee80211_sub_if_data *sdata,
47 				     struct ieee80211_sta_ht_cap *ht_cap)
48 {
49 	struct ieee80211_ht_cap *ht_capa, *ht_capa_mask;
50 	u8 *scaps, *smask;
51 	int i;
52 
53 	if (!ht_cap->ht_supported)
54 		return;
55 
56 	switch (sdata->vif.type) {
57 	case NL80211_IFTYPE_STATION:
58 		ht_capa = &sdata->u.mgd.ht_capa;
59 		ht_capa_mask = &sdata->u.mgd.ht_capa_mask;
60 		break;
61 	case NL80211_IFTYPE_ADHOC:
62 		ht_capa = &sdata->u.ibss.ht_capa;
63 		ht_capa_mask = &sdata->u.ibss.ht_capa_mask;
64 		break;
65 	default:
66 		WARN_ON_ONCE(1);
67 		return;
68 	}
69 
70 	scaps = (u8 *)(&ht_capa->mcs.rx_mask);
71 	smask = (u8 *)(&ht_capa_mask->mcs.rx_mask);
72 
73 	/* NOTE:  If you add more over-rides here, update register_hw
74 	 * ht_capa_mod_mask logic in main.c as well.
75 	 * And, if this method can ever change ht_cap.ht_supported, fix
76 	 * the check in ieee80211_add_ht_ie.
77 	 */
78 
79 	/* check for HT over-rides, MCS rates first. */
80 	for (i = 0; i < IEEE80211_HT_MCS_MASK_LEN; i++) {
81 		u8 m = smask[i];
82 		ht_cap->mcs.rx_mask[i] &= ~m; /* turn off all masked bits */
83 		/* Add back rates that are supported */
84 		ht_cap->mcs.rx_mask[i] |= (m & scaps[i]);
85 	}
86 
87 	/* Force removal of HT-40 capabilities? */
88 	__check_htcap_disable(ht_capa, ht_capa_mask, ht_cap,
89 			      IEEE80211_HT_CAP_SUP_WIDTH_20_40);
90 	__check_htcap_disable(ht_capa, ht_capa_mask, ht_cap,
91 			      IEEE80211_HT_CAP_SGI_40);
92 
93 	/* Allow user to disable SGI-20 (SGI-40 is handled above) */
94 	__check_htcap_disable(ht_capa, ht_capa_mask, ht_cap,
95 			      IEEE80211_HT_CAP_SGI_20);
96 
97 	/* Allow user to disable the max-AMSDU bit. */
98 	__check_htcap_disable(ht_capa, ht_capa_mask, ht_cap,
99 			      IEEE80211_HT_CAP_MAX_AMSDU);
100 
101 	/* Allow user to disable LDPC */
102 	__check_htcap_disable(ht_capa, ht_capa_mask, ht_cap,
103 			      IEEE80211_HT_CAP_LDPC_CODING);
104 
105 	/* Allow user to enable 40 MHz intolerant bit. */
106 	__check_htcap_enable(ht_capa, ht_capa_mask, ht_cap,
107 			     IEEE80211_HT_CAP_40MHZ_INTOLERANT);
108 
109 	/* Allow user to decrease AMPDU factor */
110 	if (ht_capa_mask->ampdu_params_info &
111 	    IEEE80211_HT_AMPDU_PARM_FACTOR) {
112 		u8 n = ht_capa->ampdu_params_info &
113 		       IEEE80211_HT_AMPDU_PARM_FACTOR;
114 		if (n < ht_cap->ampdu_factor)
115 			ht_cap->ampdu_factor = n;
116 	}
117 
118 	/* Allow the user to increase AMPDU density. */
119 	if (ht_capa_mask->ampdu_params_info &
120 	    IEEE80211_HT_AMPDU_PARM_DENSITY) {
121 		u8 n = (ht_capa->ampdu_params_info &
122 			IEEE80211_HT_AMPDU_PARM_DENSITY)
123 			>> IEEE80211_HT_AMPDU_PARM_DENSITY_SHIFT;
124 		if (n > ht_cap->ampdu_density)
125 			ht_cap->ampdu_density = n;
126 	}
127 }
128 
129 
130 bool ieee80211_ht_cap_ie_to_sta_ht_cap(struct ieee80211_sub_if_data *sdata,
131 				       struct ieee80211_supported_band *sband,
132 				       const struct ieee80211_ht_cap *ht_cap_ie,
133 				       struct sta_info *sta)
134 {
135 	struct ieee80211_sta_ht_cap ht_cap, own_cap;
136 	u8 ampdu_info, tx_mcs_set_cap;
137 	int i, max_tx_streams;
138 	bool changed;
139 	enum ieee80211_sta_rx_bandwidth bw;
140 	enum ieee80211_smps_mode smps_mode;
141 
142 	memset(&ht_cap, 0, sizeof(ht_cap));
143 
144 	if (!ht_cap_ie || !sband->ht_cap.ht_supported)
145 		goto apply;
146 
147 	ht_cap.ht_supported = true;
148 
149 	own_cap = sband->ht_cap;
150 
151 	/*
152 	 * If user has specified capability over-rides, take care
153 	 * of that if the station we're setting up is the AP or TDLS peer that
154 	 * we advertised a restricted capability set to. Override
155 	 * our own capabilities and then use those below.
156 	 */
157 	if (sdata->vif.type == NL80211_IFTYPE_STATION ||
158 	    sdata->vif.type == NL80211_IFTYPE_ADHOC)
159 		ieee80211_apply_htcap_overrides(sdata, &own_cap);
160 
161 	/*
162 	 * The bits listed in this expression should be
163 	 * the same for the peer and us, if the station
164 	 * advertises more then we can't use those thus
165 	 * we mask them out.
166 	 */
167 	ht_cap.cap = le16_to_cpu(ht_cap_ie->cap_info) &
168 		(own_cap.cap | ~(IEEE80211_HT_CAP_LDPC_CODING |
169 				 IEEE80211_HT_CAP_SUP_WIDTH_20_40 |
170 				 IEEE80211_HT_CAP_GRN_FLD |
171 				 IEEE80211_HT_CAP_SGI_20 |
172 				 IEEE80211_HT_CAP_SGI_40 |
173 				 IEEE80211_HT_CAP_DSSSCCK40));
174 
175 	/*
176 	 * The STBC bits are asymmetric -- if we don't have
177 	 * TX then mask out the peer's RX and vice versa.
178 	 */
179 	if (!(own_cap.cap & IEEE80211_HT_CAP_TX_STBC))
180 		ht_cap.cap &= ~IEEE80211_HT_CAP_RX_STBC;
181 	if (!(own_cap.cap & IEEE80211_HT_CAP_RX_STBC))
182 		ht_cap.cap &= ~IEEE80211_HT_CAP_TX_STBC;
183 
184 	ampdu_info = ht_cap_ie->ampdu_params_info;
185 	ht_cap.ampdu_factor =
186 		ampdu_info & IEEE80211_HT_AMPDU_PARM_FACTOR;
187 	ht_cap.ampdu_density =
188 		(ampdu_info & IEEE80211_HT_AMPDU_PARM_DENSITY) >> 2;
189 
190 	/* own MCS TX capabilities */
191 	tx_mcs_set_cap = own_cap.mcs.tx_params;
192 
193 	/* Copy peer MCS TX capabilities, the driver might need them. */
194 	ht_cap.mcs.tx_params = ht_cap_ie->mcs.tx_params;
195 
196 	/* can we TX with MCS rates? */
197 	if (!(tx_mcs_set_cap & IEEE80211_HT_MCS_TX_DEFINED))
198 		goto apply;
199 
200 	/* Counting from 0, therefore +1 */
201 	if (tx_mcs_set_cap & IEEE80211_HT_MCS_TX_RX_DIFF)
202 		max_tx_streams =
203 			((tx_mcs_set_cap & IEEE80211_HT_MCS_TX_MAX_STREAMS_MASK)
204 				>> IEEE80211_HT_MCS_TX_MAX_STREAMS_SHIFT) + 1;
205 	else
206 		max_tx_streams = IEEE80211_HT_MCS_TX_MAX_STREAMS;
207 
208 	/*
209 	 * 802.11n-2009 20.3.5 / 20.6 says:
210 	 * - indices 0 to 7 and 32 are single spatial stream
211 	 * - 8 to 31 are multiple spatial streams using equal modulation
212 	 *   [8..15 for two streams, 16..23 for three and 24..31 for four]
213 	 * - remainder are multiple spatial streams using unequal modulation
214 	 */
215 	for (i = 0; i < max_tx_streams; i++)
216 		ht_cap.mcs.rx_mask[i] =
217 			own_cap.mcs.rx_mask[i] & ht_cap_ie->mcs.rx_mask[i];
218 
219 	if (tx_mcs_set_cap & IEEE80211_HT_MCS_TX_UNEQUAL_MODULATION)
220 		for (i = IEEE80211_HT_MCS_UNEQUAL_MODULATION_START_BYTE;
221 		     i < IEEE80211_HT_MCS_MASK_LEN; i++)
222 			ht_cap.mcs.rx_mask[i] =
223 				own_cap.mcs.rx_mask[i] &
224 					ht_cap_ie->mcs.rx_mask[i];
225 
226 	/* handle MCS rate 32 too */
227 	if (own_cap.mcs.rx_mask[32/8] & ht_cap_ie->mcs.rx_mask[32/8] & 1)
228 		ht_cap.mcs.rx_mask[32/8] |= 1;
229 
230 	/* set Rx highest rate */
231 	ht_cap.mcs.rx_highest = ht_cap_ie->mcs.rx_highest;
232 
233  apply:
234 	changed = memcmp(&sta->sta.ht_cap, &ht_cap, sizeof(ht_cap));
235 
236 	memcpy(&sta->sta.ht_cap, &ht_cap, sizeof(ht_cap));
237 
238 	switch (sdata->vif.bss_conf.chandef.width) {
239 	default:
240 		WARN_ON_ONCE(1);
241 		/* fall through */
242 	case NL80211_CHAN_WIDTH_20_NOHT:
243 	case NL80211_CHAN_WIDTH_20:
244 		bw = IEEE80211_STA_RX_BW_20;
245 		break;
246 	case NL80211_CHAN_WIDTH_40:
247 	case NL80211_CHAN_WIDTH_80:
248 	case NL80211_CHAN_WIDTH_80P80:
249 	case NL80211_CHAN_WIDTH_160:
250 		bw = ht_cap.cap & IEEE80211_HT_CAP_SUP_WIDTH_20_40 ?
251 				IEEE80211_STA_RX_BW_40 : IEEE80211_STA_RX_BW_20;
252 		break;
253 	}
254 
255 	sta->sta.bandwidth = bw;
256 
257 	sta->cur_max_bandwidth =
258 		ht_cap.cap & IEEE80211_HT_CAP_SUP_WIDTH_20_40 ?
259 				IEEE80211_STA_RX_BW_40 : IEEE80211_STA_RX_BW_20;
260 
261 	switch ((ht_cap.cap & IEEE80211_HT_CAP_SM_PS)
262 			>> IEEE80211_HT_CAP_SM_PS_SHIFT) {
263 	case WLAN_HT_CAP_SM_PS_INVALID:
264 	case WLAN_HT_CAP_SM_PS_STATIC:
265 		smps_mode = IEEE80211_SMPS_STATIC;
266 		break;
267 	case WLAN_HT_CAP_SM_PS_DYNAMIC:
268 		smps_mode = IEEE80211_SMPS_DYNAMIC;
269 		break;
270 	case WLAN_HT_CAP_SM_PS_DISABLED:
271 		smps_mode = IEEE80211_SMPS_OFF;
272 		break;
273 	}
274 
275 	if (smps_mode != sta->sta.smps_mode)
276 		changed = true;
277 	sta->sta.smps_mode = smps_mode;
278 
279 	return changed;
280 }
281 
282 void ieee80211_sta_tear_down_BA_sessions(struct sta_info *sta,
283 					 enum ieee80211_agg_stop_reason reason)
284 {
285 	int i;
286 
287 	cancel_work_sync(&sta->ampdu_mlme.work);
288 
289 	for (i = 0; i <  IEEE80211_NUM_TIDS; i++) {
290 		__ieee80211_stop_tx_ba_session(sta, i, reason);
291 		__ieee80211_stop_rx_ba_session(sta, i, WLAN_BACK_RECIPIENT,
292 					       WLAN_REASON_QSTA_LEAVE_QBSS,
293 					       reason != AGG_STOP_DESTROY_STA &&
294 					       reason != AGG_STOP_PEER_REQUEST);
295 	}
296 }
297 
298 void ieee80211_ba_session_work(struct work_struct *work)
299 {
300 	struct sta_info *sta =
301 		container_of(work, struct sta_info, ampdu_mlme.work);
302 	struct tid_ampdu_tx *tid_tx;
303 	int tid;
304 
305 	/*
306 	 * When this flag is set, new sessions should be
307 	 * blocked, and existing sessions will be torn
308 	 * down by the code that set the flag, so this
309 	 * need not run.
310 	 */
311 	if (test_sta_flag(sta, WLAN_STA_BLOCK_BA))
312 		return;
313 
314 	mutex_lock(&sta->ampdu_mlme.mtx);
315 	for (tid = 0; tid < IEEE80211_NUM_TIDS; tid++) {
316 		if (test_and_clear_bit(tid, sta->ampdu_mlme.tid_rx_timer_expired))
317 			___ieee80211_stop_rx_ba_session(
318 				sta, tid, WLAN_BACK_RECIPIENT,
319 				WLAN_REASON_QSTA_TIMEOUT, true);
320 
321 		if (test_and_clear_bit(tid,
322 				       sta->ampdu_mlme.tid_rx_stop_requested))
323 			___ieee80211_stop_rx_ba_session(
324 				sta, tid, WLAN_BACK_RECIPIENT,
325 				WLAN_REASON_UNSPECIFIED, true);
326 
327 		spin_lock_bh(&sta->lock);
328 
329 		tid_tx = sta->ampdu_mlme.tid_start_tx[tid];
330 		if (tid_tx) {
331 			/*
332 			 * Assign it over to the normal tid_tx array
333 			 * where it "goes live".
334 			 */
335 
336 			sta->ampdu_mlme.tid_start_tx[tid] = NULL;
337 			/* could there be a race? */
338 			if (sta->ampdu_mlme.tid_tx[tid])
339 				kfree(tid_tx);
340 			else
341 				ieee80211_assign_tid_tx(sta, tid, tid_tx);
342 			spin_unlock_bh(&sta->lock);
343 
344 			ieee80211_tx_ba_session_handle_start(sta, tid);
345 			continue;
346 		}
347 		spin_unlock_bh(&sta->lock);
348 
349 		tid_tx = rcu_dereference_protected_tid_tx(sta, tid);
350 		if (tid_tx && test_and_clear_bit(HT_AGG_STATE_WANT_STOP,
351 						 &tid_tx->state))
352 			___ieee80211_stop_tx_ba_session(sta, tid,
353 							AGG_STOP_LOCAL_REQUEST);
354 	}
355 	mutex_unlock(&sta->ampdu_mlme.mtx);
356 }
357 
358 void ieee80211_send_delba(struct ieee80211_sub_if_data *sdata,
359 			  const u8 *da, u16 tid,
360 			  u16 initiator, u16 reason_code)
361 {
362 	struct ieee80211_local *local = sdata->local;
363 	struct sk_buff *skb;
364 	struct ieee80211_mgmt *mgmt;
365 	u16 params;
366 
367 	skb = dev_alloc_skb(sizeof(*mgmt) + local->hw.extra_tx_headroom);
368 	if (!skb)
369 		return;
370 
371 	skb_reserve(skb, local->hw.extra_tx_headroom);
372 	mgmt = (struct ieee80211_mgmt *) skb_put(skb, 24);
373 	memset(mgmt, 0, 24);
374 	memcpy(mgmt->da, da, ETH_ALEN);
375 	memcpy(mgmt->sa, sdata->vif.addr, ETH_ALEN);
376 	if (sdata->vif.type == NL80211_IFTYPE_AP ||
377 	    sdata->vif.type == NL80211_IFTYPE_AP_VLAN ||
378 	    sdata->vif.type == NL80211_IFTYPE_MESH_POINT)
379 		memcpy(mgmt->bssid, sdata->vif.addr, ETH_ALEN);
380 	else if (sdata->vif.type == NL80211_IFTYPE_STATION)
381 		memcpy(mgmt->bssid, sdata->u.mgd.bssid, ETH_ALEN);
382 	else if (sdata->vif.type == NL80211_IFTYPE_ADHOC)
383 		memcpy(mgmt->bssid, sdata->u.ibss.bssid, ETH_ALEN);
384 
385 	mgmt->frame_control = cpu_to_le16(IEEE80211_FTYPE_MGMT |
386 					  IEEE80211_STYPE_ACTION);
387 
388 	skb_put(skb, 1 + sizeof(mgmt->u.action.u.delba));
389 
390 	mgmt->u.action.category = WLAN_CATEGORY_BACK;
391 	mgmt->u.action.u.delba.action_code = WLAN_ACTION_DELBA;
392 	params = (u16)(initiator << 11); 	/* bit 11 initiator */
393 	params |= (u16)(tid << 12); 		/* bit 15:12 TID number */
394 
395 	mgmt->u.action.u.delba.params = cpu_to_le16(params);
396 	mgmt->u.action.u.delba.reason_code = cpu_to_le16(reason_code);
397 
398 	ieee80211_tx_skb(sdata, skb);
399 }
400 
401 void ieee80211_process_delba(struct ieee80211_sub_if_data *sdata,
402 			     struct sta_info *sta,
403 			     struct ieee80211_mgmt *mgmt, size_t len)
404 {
405 	u16 tid, params;
406 	u16 initiator;
407 
408 	params = le16_to_cpu(mgmt->u.action.u.delba.params);
409 	tid = (params & IEEE80211_DELBA_PARAM_TID_MASK) >> 12;
410 	initiator = (params & IEEE80211_DELBA_PARAM_INITIATOR_MASK) >> 11;
411 
412 	ht_dbg_ratelimited(sdata, "delba from %pM (%s) tid %d reason code %d\n",
413 			   mgmt->sa, initiator ? "initiator" : "recipient",
414 			   tid,
415 			   le16_to_cpu(mgmt->u.action.u.delba.reason_code));
416 
417 	if (initiator == WLAN_BACK_INITIATOR)
418 		__ieee80211_stop_rx_ba_session(sta, tid, WLAN_BACK_INITIATOR, 0,
419 					       true);
420 	else
421 		__ieee80211_stop_tx_ba_session(sta, tid, AGG_STOP_PEER_REQUEST);
422 }
423 
424 int ieee80211_send_smps_action(struct ieee80211_sub_if_data *sdata,
425 			       enum ieee80211_smps_mode smps, const u8 *da,
426 			       const u8 *bssid)
427 {
428 	struct ieee80211_local *local = sdata->local;
429 	struct sk_buff *skb;
430 	struct ieee80211_mgmt *action_frame;
431 
432 	/* 27 = header + category + action + smps mode */
433 	skb = dev_alloc_skb(27 + local->hw.extra_tx_headroom);
434 	if (!skb)
435 		return -ENOMEM;
436 
437 	skb_reserve(skb, local->hw.extra_tx_headroom);
438 	action_frame = (void *)skb_put(skb, 27);
439 	memcpy(action_frame->da, da, ETH_ALEN);
440 	memcpy(action_frame->sa, sdata->dev->dev_addr, ETH_ALEN);
441 	memcpy(action_frame->bssid, bssid, ETH_ALEN);
442 	action_frame->frame_control = cpu_to_le16(IEEE80211_FTYPE_MGMT |
443 						  IEEE80211_STYPE_ACTION);
444 	action_frame->u.action.category = WLAN_CATEGORY_HT;
445 	action_frame->u.action.u.ht_smps.action = WLAN_HT_ACTION_SMPS;
446 	switch (smps) {
447 	case IEEE80211_SMPS_AUTOMATIC:
448 	case IEEE80211_SMPS_NUM_MODES:
449 		WARN_ON(1);
450 	case IEEE80211_SMPS_OFF:
451 		action_frame->u.action.u.ht_smps.smps_control =
452 				WLAN_HT_SMPS_CONTROL_DISABLED;
453 		break;
454 	case IEEE80211_SMPS_STATIC:
455 		action_frame->u.action.u.ht_smps.smps_control =
456 				WLAN_HT_SMPS_CONTROL_STATIC;
457 		break;
458 	case IEEE80211_SMPS_DYNAMIC:
459 		action_frame->u.action.u.ht_smps.smps_control =
460 				WLAN_HT_SMPS_CONTROL_DYNAMIC;
461 		break;
462 	}
463 
464 	/* we'll do more on status of this frame */
465 	IEEE80211_SKB_CB(skb)->flags |= IEEE80211_TX_CTL_REQ_TX_STATUS;
466 	ieee80211_tx_skb(sdata, skb);
467 
468 	return 0;
469 }
470 
471 void ieee80211_request_smps_mgd_work(struct work_struct *work)
472 {
473 	struct ieee80211_sub_if_data *sdata =
474 		container_of(work, struct ieee80211_sub_if_data,
475 			     u.mgd.request_smps_work);
476 
477 	sdata_lock(sdata);
478 	__ieee80211_request_smps_mgd(sdata, sdata->u.mgd.driver_smps_mode);
479 	sdata_unlock(sdata);
480 }
481 
482 void ieee80211_request_smps_ap_work(struct work_struct *work)
483 {
484 	struct ieee80211_sub_if_data *sdata =
485 		container_of(work, struct ieee80211_sub_if_data,
486 			     u.ap.request_smps_work);
487 
488 	sdata_lock(sdata);
489 	if (sdata_dereference(sdata->u.ap.beacon, sdata))
490 		__ieee80211_request_smps_ap(sdata,
491 					    sdata->u.ap.driver_smps_mode);
492 	sdata_unlock(sdata);
493 }
494 
495 void ieee80211_request_smps(struct ieee80211_vif *vif,
496 			    enum ieee80211_smps_mode smps_mode)
497 {
498 	struct ieee80211_sub_if_data *sdata = vif_to_sdata(vif);
499 
500 	if (WARN_ON_ONCE(vif->type != NL80211_IFTYPE_STATION &&
501 			 vif->type != NL80211_IFTYPE_AP))
502 		return;
503 
504 	if (vif->type == NL80211_IFTYPE_STATION) {
505 		if (sdata->u.mgd.driver_smps_mode == smps_mode)
506 			return;
507 		sdata->u.mgd.driver_smps_mode = smps_mode;
508 		ieee80211_queue_work(&sdata->local->hw,
509 				     &sdata->u.mgd.request_smps_work);
510 	} else {
511 		/* AUTOMATIC is meaningless in AP mode */
512 		if (WARN_ON_ONCE(smps_mode == IEEE80211_SMPS_AUTOMATIC))
513 			return;
514 		if (sdata->u.ap.driver_smps_mode == smps_mode)
515 			return;
516 		sdata->u.ap.driver_smps_mode = smps_mode;
517 		ieee80211_queue_work(&sdata->local->hw,
518 				     &sdata->u.ap.request_smps_work);
519 	}
520 }
521 /* this might change ... don't want non-open drivers using it */
522 EXPORT_SYMBOL_GPL(ieee80211_request_smps);
523