net/mac80211/ht.c

   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  apply:
 231         changed = memcmp(&sta->sta.ht_cap, &ht_cap, sizeof(ht_cap));
 232
 233         memcpy(&sta->sta.ht_cap, &ht_cap, sizeof(ht_cap));
 234
 235         switch (sdata->vif.bss_conf.chandef.width) {
 236         default:
 237                 WARN_ON_ONCE(1);
 238                 /* fall through */
 239         case NL80211_CHAN_WIDTH_20_NOHT:
 240         case NL80211_CHAN_WIDTH_20:
 241                 bw = IEEE80211_STA_RX_BW_20;
 242                 break;
 243         case NL80211_CHAN_WIDTH_40:
 244         case NL80211_CHAN_WIDTH_80:
 245         case NL80211_CHAN_WIDTH_80P80:
 246         case NL80211_CHAN_WIDTH_160:
 247                 bw = ht_cap.cap & IEEE80211_HT_CAP_SUP_WIDTH_20_40 ?
 248                                 IEEE80211_STA_RX_BW_40 : IEEE80211_STA_RX_BW_20;
 249                 break;
 250         }
 251
 252         if (bw != sta->sta.bandwidth)
 253                 changed = true;
 254         sta->sta.bandwidth = bw;
 255
 256         sta->cur_max_bandwidth =
 257                 ht_cap.cap & IEEE80211_HT_CAP_SUP_WIDTH_20_40 ?
 258                                 IEEE80211_STA_RX_BW_40 : IEEE80211_STA_RX_BW_20;
 259
 260         switch ((ht_cap.cap & IEEE80211_HT_CAP_SM_PS)
 261                         >> IEEE80211_HT_CAP_SM_PS_SHIFT) {
 262         case WLAN_HT_CAP_SM_PS_INVALID:
 263         case WLAN_HT_CAP_SM_PS_STATIC:
 264                 smps_mode = IEEE80211_SMPS_STATIC;
 265                 break;
 266         case WLAN_HT_CAP_SM_PS_DYNAMIC:
 267                 smps_mode = IEEE80211_SMPS_DYNAMIC;
 268                 break;
 269         case WLAN_HT_CAP_SM_PS_DISABLED:
 270                 smps_mode = IEEE80211_SMPS_OFF;
 271                 break;
 272         }
 273
 274         if (smps_mode != sta->sta.smps_mode)
 275                 changed = true;
 276         sta->sta.smps_mode = smps_mode;
 277
 278         return changed;
 279 }
 280
 281 void ieee80211_sta_tear_down_BA_sessions(struct sta_info *sta,
 282                                          enum ieee80211_agg_stop_reason reason)
 283 {
 284         int i;
 285
 286         cancel_work_sync(&sta->ampdu_mlme.work);
 287
 288         for (i = 0; i <  IEEE80211_NUM_TIDS; i++) {
 289                 __ieee80211_stop_tx_ba_session(sta, i, reason);
 290                 __ieee80211_stop_rx_ba_session(sta, i, WLAN_BACK_RECIPIENT,
 291                                                WLAN_REASON_QSTA_LEAVE_QBSS,
 292                                                reason != AGG_STOP_DESTROY_STA &&
 293                                                reason != AGG_STOP_PEER_REQUEST);
 294         }
 295 }
 296
 297 void ieee80211_ba_session_work(struct work_struct *work)
 298 {
 299         struct sta_info *sta =
 300                 container_of(work, struct sta_info, ampdu_mlme.work);
 301         struct tid_ampdu_tx *tid_tx;
 302         int tid;
 303
 304         /*
 305          * When this flag is set, new sessions should be
 306          * blocked, and existing sessions will be torn
 307          * down by the code that set the flag, so this
 308          * need not run.
 309          */
 310         if (test_sta_flag(sta, WLAN_STA_BLOCK_BA))
 311                 return;
 312
 313         mutex_lock(&sta->ampdu_mlme.mtx);
 314         for (tid = 0; tid < IEEE80211_NUM_TIDS; tid++) {
 315                 if (test_and_clear_bit(tid, sta->ampdu_mlme.tid_rx_timer_expired))
 316                         ___ieee80211_stop_rx_ba_session(
 317                                 sta, tid, WLAN_BACK_RECIPIENT,
 318                                 WLAN_REASON_QSTA_TIMEOUT, true);
 319
 320                 if (test_and_clear_bit(tid,
 321                                        sta->ampdu_mlme.tid_rx_stop_requested))
 322                         ___ieee80211_stop_rx_ba_session(
 323                                 sta, tid, WLAN_BACK_RECIPIENT,
 324                                 WLAN_REASON_UNSPECIFIED, true);
 325
 326                 spin_lock_bh(&sta->lock);
 327
 328                 tid_tx = sta->ampdu_mlme.tid_start_tx[tid];
 329                 if (tid_tx) {
 330                         /*
 331                          * Assign it over to the normal tid_tx array
 332                          * where it "goes live".
 333                          */
 334
 335                         sta->ampdu_mlme.tid_start_tx[tid] = NULL;
 336                         /* could there be a race? */
 337                         if (sta->ampdu_mlme.tid_tx[tid])
 338                                 kfree(tid_tx);
 339                         else
 340                                 ieee80211_assign_tid_tx(sta, tid, tid_tx);
 341                         spin_unlock_bh(&sta->lock);
 342
 343                         ieee80211_tx_ba_session_handle_start(sta, tid);
 344                         continue;
 345                 }
 346                 spin_unlock_bh(&sta->lock);
 347
 348                 tid_tx = rcu_dereference_protected_tid_tx(sta, tid);
 349                 if (tid_tx && test_and_clear_bit(HT_AGG_STATE_WANT_STOP,
 350                                                  &tid_tx->state))
 351                         ___ieee80211_stop_tx_ba_session(sta, tid,
 352                                                         AGG_STOP_LOCAL_REQUEST);
 353         }
 354         mutex_unlock(&sta->ampdu_mlme.mtx);
 355 }
 356
 357 void ieee80211_send_delba(struct ieee80211_sub_if_data *sdata,
 358                           const u8 *da, u16 tid,
 359                           u16 initiator, u16 reason_code)
 360 {
 361         struct ieee80211_local *local = sdata->local;
 362         struct sk_buff *skb;
 363         struct ieee80211_mgmt *mgmt;
 364         u16 params;
 365
 366         skb = dev_alloc_skb(sizeof(*mgmt) + local->hw.extra_tx_headroom);
 367         if (!skb)
 368                 return;
 369
 370         skb_reserve(skb, local->hw.extra_tx_headroom);
 371         mgmt = (struct ieee80211_mgmt *) skb_put(skb, 24);
 372         memset(mgmt, 0, 24);
 373         memcpy(mgmt->da, da, ETH_ALEN);
 374         memcpy(mgmt->sa, sdata->vif.addr, ETH_ALEN);
 375         if (sdata->vif.type == NL80211_IFTYPE_AP ||
 376             sdata->vif.type == NL80211_IFTYPE_AP_VLAN ||
 377             sdata->vif.type == NL80211_IFTYPE_MESH_POINT)
 378                 memcpy(mgmt->bssid, sdata->vif.addr, ETH_ALEN);
 379         else if (sdata->vif.type == NL80211_IFTYPE_STATION)
 380                 memcpy(mgmt->bssid, sdata->u.mgd.bssid, ETH_ALEN);
 381         else if (sdata->vif.type == NL80211_IFTYPE_ADHOC)
 382                 memcpy(mgmt->bssid, sdata->u.ibss.bssid, ETH_ALEN);
 383
 384         mgmt->frame_control = cpu_to_le16(IEEE80211_FTYPE_MGMT |
 385                                           IEEE80211_STYPE_ACTION);
 386
 387         skb_put(skb, 1 + sizeof(mgmt->u.action.u.delba));
 388
 389         mgmt->u.action.category = WLAN_CATEGORY_BACK;
 390         mgmt->u.action.u.delba.action_code = WLAN_ACTION_DELBA;
 391         params = (u16)(initiator << 11);        /* bit 11 initiator */
 392         params |= (u16)(tid << 12);             /* bit 15:12 TID number */
 393
 394         mgmt->u.action.u.delba.params = cpu_to_le16(params);
 395         mgmt->u.action.u.delba.reason_code = cpu_to_le16(reason_code);
 396
 397         ieee80211_tx_skb(sdata, skb);
 398 }
 399
 400 void ieee80211_process_delba(struct ieee80211_sub_if_data *sdata,
 401                              struct sta_info *sta,
 402                              struct ieee80211_mgmt *mgmt, size_t len)
 403 {
 404         u16 tid, params;
 405         u16 initiator;
 406
 407         params = le16_to_cpu(mgmt->u.action.u.delba.params);
 408         tid = (params & IEEE80211_DELBA_PARAM_TID_MASK) >> 12;
 409         initiator = (params & IEEE80211_DELBA_PARAM_INITIATOR_MASK) >> 11;
 410
 411         ht_dbg_ratelimited(sdata, "delba from %pM (%s) tid %d reason code %d\n",
 412                            mgmt->sa, initiator ? "initiator" : "recipient",
 413                            tid,
 414                            le16_to_cpu(mgmt->u.action.u.delba.reason_code));
 415
 416         if (initiator == WLAN_BACK_INITIATOR)
 417                 __ieee80211_stop_rx_ba_session(sta, tid, WLAN_BACK_INITIATOR, 0,
 418                                                true);
 419         else
 420                 __ieee80211_stop_tx_ba_session(sta, tid, AGG_STOP_PEER_REQUEST);
 421 }
 422
 423 int ieee80211_send_smps_action(struct ieee80211_sub_if_data *sdata,
 424                                enum ieee80211_smps_mode smps, const u8 *da,
 425                                const u8 *bssid)
 426 {
 427         struct ieee80211_local *local = sdata->local;
 428         struct sk_buff *skb;
 429         struct ieee80211_mgmt *action_frame;
 430
 431         /* 27 = header + category + action + smps mode */
 432         skb = dev_alloc_skb(27 + local->hw.extra_tx_headroom);
 433         if (!skb)
 434                 return -ENOMEM;
 435
 436         skb_reserve(skb, local->hw.extra_tx_headroom);
 437         action_frame = (void *)skb_put(skb, 27);
 438         memcpy(action_frame->da, da, ETH_ALEN);
 439         memcpy(action_frame->sa, sdata->dev->dev_addr, ETH_ALEN);
 440         memcpy(action_frame->bssid, bssid, ETH_ALEN);
 441         action_frame->frame_control = cpu_to_le16(IEEE80211_FTYPE_MGMT |
 442                                                   IEEE80211_STYPE_ACTION);
 443         action_frame->u.action.category = WLAN_CATEGORY_HT;
 444         action_frame->u.action.u.ht_smps.action = WLAN_HT_ACTION_SMPS;
 445         switch (smps) {
 446         case IEEE80211_SMPS_AUTOMATIC:
 447         case IEEE80211_SMPS_NUM_MODES:
 448                 WARN_ON(1);
 449         case IEEE80211_SMPS_OFF:
 450                 action_frame->u.action.u.ht_smps.smps_control =
 451                                 WLAN_HT_SMPS_CONTROL_DISABLED;
 452                 break;
 453         case IEEE80211_SMPS_STATIC:
 454                 action_frame->u.action.u.ht_smps.smps_control =
 455                                 WLAN_HT_SMPS_CONTROL_STATIC;
 456                 break;
 457         case IEEE80211_SMPS_DYNAMIC:
 458                 action_frame->u.action.u.ht_smps.smps_control =
 459                                 WLAN_HT_SMPS_CONTROL_DYNAMIC;
 460                 break;
 461         }
 462
 463         /* we'll do more on status of this frame */
 464         IEEE80211_SKB_CB(skb)->flags |= IEEE80211_TX_CTL_REQ_TX_STATUS;
 465         ieee80211_tx_skb(sdata, skb);
 466
 467         return 0;
 468 }
 469
 470 void ieee80211_request_smps_mgd_work(struct work_struct *work)
 471 {
 472         struct ieee80211_sub_if_data *sdata =
 473                 container_of(work, struct ieee80211_sub_if_data,
 474                              u.mgd.request_smps_work);
 475
 476         sdata_lock(sdata);
 477         __ieee80211_request_smps_mgd(sdata, sdata->u.mgd.driver_smps_mode);
 478         sdata_unlock(sdata);
 479 }
 480
 481 void ieee80211_request_smps_ap_work(struct work_struct *work)
 482 {
 483         struct ieee80211_sub_if_data *sdata =
 484                 container_of(work, struct ieee80211_sub_if_data,
 485                              u.ap.request_smps_work);
 486
 487         sdata_lock(sdata);
 488         if (sdata_dereference(sdata->u.ap.beacon, sdata))
 489                 __ieee80211_request_smps_ap(sdata,
 490                                             sdata->u.ap.driver_smps_mode);
 491         sdata_unlock(sdata);
 492 }
 493
 494 void ieee80211_request_smps(struct ieee80211_vif *vif,
 495                             enum ieee80211_smps_mode smps_mode)
 496 {
 497         struct ieee80211_sub_if_data *sdata = vif_to_sdata(vif);
 498
 499         if (WARN_ON_ONCE(vif->type != NL80211_IFTYPE_STATION &&
 500                          vif->type != NL80211_IFTYPE_AP))
 501                 return;
 502
 503         if (vif->type == NL80211_IFTYPE_STATION) {
 504                 if (sdata->u.mgd.driver_smps_mode == smps_mode)
 505                         return;
 506                 sdata->u.mgd.driver_smps_mode = smps_mode;
 507                 ieee80211_queue_work(&sdata->local->hw,
 508                                      &sdata->u.mgd.request_smps_work);
 509         } else {
 510                 /* AUTOMATIC is meaningless in AP mode */
 511                 if (WARN_ON_ONCE(smps_mode == IEEE80211_SMPS_AUTOMATIC))
 512                         return;
 513                 if (sdata->u.ap.driver_smps_mode == smps_mode)
 514                         return;
 515                 sdata->u.ap.driver_smps_mode = smps_mode;
 516                 ieee80211_queue_work(&sdata->local->hw,
 517                                      &sdata->u.ap.request_smps_work);
 518         }
 519 }
 520 /* this might change ... don't want non-open drivers using it */
 521 EXPORT_SYMBOL_GPL(ieee80211_request_smps);