net/mac80211/vht.c

   1 /*
   2  * VHT handling
   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
   9 #include <linux/ieee80211.h>
  10 #include <linux/export.h>
  11 #include <net/mac80211.h>
  12 #include "ieee80211_i.h"
  13 #include "rate.h"
  14
  15
  16 static void __check_vhtcap_disable(struct ieee80211_sub_if_data *sdata,
  17                                    struct ieee80211_sta_vht_cap *vht_cap,
  18                                    u32 flag)
  19 {
  20         __le32 le_flag = cpu_to_le32(flag);
  21
  22         if (sdata->u.mgd.vht_capa_mask.vht_cap_info & le_flag &&
  23             !(sdata->u.mgd.vht_capa.vht_cap_info & le_flag))
  24                 vht_cap->cap &= ~flag;
  25 }
  26
  27 void ieee80211_apply_vhtcap_overrides(struct ieee80211_sub_if_data *sdata,
  28                                       struct ieee80211_sta_vht_cap *vht_cap)
  29 {
  30         int i;
  31         u16 rxmcs_mask, rxmcs_cap, rxmcs_n, txmcs_mask, txmcs_cap, txmcs_n;
  32
  33         if (!vht_cap->vht_supported)
  34                 return;
  35
  36         if (sdata->vif.type != NL80211_IFTYPE_STATION)
  37                 return;
  38
  39         __check_vhtcap_disable(sdata, vht_cap,
  40                                IEEE80211_VHT_CAP_RXLDPC);
  41         __check_vhtcap_disable(sdata, vht_cap,
  42                                IEEE80211_VHT_CAP_SHORT_GI_80);
  43         __check_vhtcap_disable(sdata, vht_cap,
  44                                IEEE80211_VHT_CAP_SHORT_GI_160);
  45         __check_vhtcap_disable(sdata, vht_cap,
  46                                IEEE80211_VHT_CAP_TXSTBC);
  47         __check_vhtcap_disable(sdata, vht_cap,
  48                                IEEE80211_VHT_CAP_SU_BEAMFORMER_CAPABLE);
  49         __check_vhtcap_disable(sdata, vht_cap,
  50                                IEEE80211_VHT_CAP_SU_BEAMFORMEE_CAPABLE);
  51         __check_vhtcap_disable(sdata, vht_cap,
  52                                IEEE80211_VHT_CAP_RX_ANTENNA_PATTERN);
  53         __check_vhtcap_disable(sdata, vht_cap,
  54                                IEEE80211_VHT_CAP_TX_ANTENNA_PATTERN);
  55
  56         /* Allow user to decrease AMPDU length exponent */
  57         if (sdata->u.mgd.vht_capa_mask.vht_cap_info &
  58             cpu_to_le32(IEEE80211_VHT_CAP_MAX_A_MPDU_LENGTH_EXPONENT_MASK)) {
  59                 u32 cap, n;
  60
  61                 n = le32_to_cpu(sdata->u.mgd.vht_capa.vht_cap_info) &
  62                         IEEE80211_VHT_CAP_MAX_A_MPDU_LENGTH_EXPONENT_MASK;
  63                 n >>= IEEE80211_VHT_CAP_MAX_A_MPDU_LENGTH_EXPONENT_SHIFT;
  64                 cap = vht_cap->cap & IEEE80211_VHT_CAP_MAX_A_MPDU_LENGTH_EXPONENT_MASK;
  65                 cap >>= IEEE80211_VHT_CAP_MAX_A_MPDU_LENGTH_EXPONENT_SHIFT;
  66
  67                 if (n < cap) {
  68                         vht_cap->cap &=
  69                                 ~IEEE80211_VHT_CAP_MAX_A_MPDU_LENGTH_EXPONENT_MASK;
  70                         vht_cap->cap |=
  71                                 n << IEEE80211_VHT_CAP_MAX_A_MPDU_LENGTH_EXPONENT_SHIFT;
  72                 }
  73         }
  74
  75         /* Allow the user to decrease MCSes */
  76         rxmcs_mask =
  77                 le16_to_cpu(sdata->u.mgd.vht_capa_mask.supp_mcs.rx_mcs_map);
  78         rxmcs_n = le16_to_cpu(sdata->u.mgd.vht_capa.supp_mcs.rx_mcs_map);
  79         rxmcs_n &= rxmcs_mask;
  80         rxmcs_cap = le16_to_cpu(vht_cap->vht_mcs.rx_mcs_map);
  81
  82         txmcs_mask =
  83                 le16_to_cpu(sdata->u.mgd.vht_capa_mask.supp_mcs.tx_mcs_map);
  84         txmcs_n = le16_to_cpu(sdata->u.mgd.vht_capa.supp_mcs.tx_mcs_map);
  85         txmcs_n &= txmcs_mask;
  86         txmcs_cap = le16_to_cpu(vht_cap->vht_mcs.tx_mcs_map);
  87         for (i = 0; i < 8; i++) {
  88                 u8 m, n, c;
  89
  90                 m = (rxmcs_mask >> 2*i) & IEEE80211_VHT_MCS_NOT_SUPPORTED;
  91                 n = (rxmcs_n >> 2*i) & IEEE80211_VHT_MCS_NOT_SUPPORTED;
  92                 c = (rxmcs_cap >> 2*i) & IEEE80211_VHT_MCS_NOT_SUPPORTED;
  93
  94                 if (m && ((c != IEEE80211_VHT_MCS_NOT_SUPPORTED && n < c) ||
  95                           n == IEEE80211_VHT_MCS_NOT_SUPPORTED)) {
  96                         rxmcs_cap &= ~(3 << 2*i);
  97                         rxmcs_cap |= (rxmcs_n & (3 << 2*i));
  98                 }
  99
 100                 m = (txmcs_mask >> 2*i) & IEEE80211_VHT_MCS_NOT_SUPPORTED;
 101                 n = (txmcs_n >> 2*i) & IEEE80211_VHT_MCS_NOT_SUPPORTED;
 102                 c = (txmcs_cap >> 2*i) & IEEE80211_VHT_MCS_NOT_SUPPORTED;
 103
 104                 if (m && ((c != IEEE80211_VHT_MCS_NOT_SUPPORTED && n < c) ||
 105                           n == IEEE80211_VHT_MCS_NOT_SUPPORTED)) {
 106                         txmcs_cap &= ~(3 << 2*i);
 107                         txmcs_cap |= (txmcs_n & (3 << 2*i));
 108                 }
 109         }
 110         vht_cap->vht_mcs.rx_mcs_map = cpu_to_le16(rxmcs_cap);
 111         vht_cap->vht_mcs.tx_mcs_map = cpu_to_le16(txmcs_cap);
 112 }
 113
 114 void
 115 ieee80211_vht_cap_ie_to_sta_vht_cap(struct ieee80211_sub_if_data *sdata,
 116                                     struct ieee80211_supported_band *sband,
 117                                     const struct ieee80211_vht_cap *vht_cap_ie,
 118                                     struct sta_info *sta)
 119 {
 120         struct ieee80211_sta_vht_cap *vht_cap = &sta->sta.vht_cap;
 121         struct ieee80211_sta_vht_cap own_cap;
 122         u32 cap_info, i;
 123         bool have_80mhz;
 124
 125         memset(vht_cap, 0, sizeof(*vht_cap));
 126
 127         if (!sta->sta.ht_cap.ht_supported)
 128                 return;
 129
 130         if (!vht_cap_ie || !sband->vht_cap.vht_supported)
 131                 return;
 132
 133         /* Allow VHT if at least one channel on the sband supports 80 MHz */
 134         have_80mhz = false;
 135         for (i = 0; i < sband->n_channels; i++) {
 136                 if (sband->channels[i].flags & (IEEE80211_CHAN_DISABLED |
 137                                                 IEEE80211_CHAN_NO_80MHZ))
 138                         continue;
 139
 140                 have_80mhz = true;
 141                 break;
 142         }
 143
 144         if (!have_80mhz)
 145                 return;
 146
 147         /*
 148          * A VHT STA must support 40 MHz, but if we verify that here
 149          * then we break a few things - some APs (e.g. Netgear R6300v2
 150          * and others based on the BCM4360 chipset) will unset this
 151          * capability bit when operating in 20 MHz.
 152          */
 153
 154         vht_cap->vht_supported = true;
 155
 156         own_cap = sband->vht_cap;
 157         /*
 158          * If user has specified capability overrides, take care
 159          * of that if the station we're setting up is the AP that
 160          * we advertised a restricted capability set to. Override
 161          * our own capabilities and then use those below.
 162          */
 163         if (sdata->vif.type == NL80211_IFTYPE_STATION &&
 164             !test_sta_flag(sta, WLAN_STA_TDLS_PEER))
 165                 ieee80211_apply_vhtcap_overrides(sdata, &own_cap);
 166
 167         /* take some capabilities as-is */
 168         cap_info = le32_to_cpu(vht_cap_ie->vht_cap_info);
 169         vht_cap->cap = cap_info;
 170         vht_cap->cap &= IEEE80211_VHT_CAP_MAX_MPDU_LENGTH_3895 |
 171                         IEEE80211_VHT_CAP_MAX_MPDU_LENGTH_7991 |
 172                         IEEE80211_VHT_CAP_MAX_MPDU_LENGTH_11454 |
 173                         IEEE80211_VHT_CAP_RXLDPC |
 174                         IEEE80211_VHT_CAP_VHT_TXOP_PS |
 175                         IEEE80211_VHT_CAP_HTC_VHT |
 176                         IEEE80211_VHT_CAP_MAX_A_MPDU_LENGTH_EXPONENT_MASK |
 177                         IEEE80211_VHT_CAP_VHT_LINK_ADAPTATION_VHT_UNSOL_MFB |
 178                         IEEE80211_VHT_CAP_VHT_LINK_ADAPTATION_VHT_MRQ_MFB |
 179                         IEEE80211_VHT_CAP_RX_ANTENNA_PATTERN |
 180                         IEEE80211_VHT_CAP_TX_ANTENNA_PATTERN;
 181
 182         /* and some based on our own capabilities */
 183         switch (own_cap.cap & IEEE80211_VHT_CAP_SUPP_CHAN_WIDTH_MASK) {
 184         case IEEE80211_VHT_CAP_SUPP_CHAN_WIDTH_160MHZ:
 185                 vht_cap->cap |= cap_info &
 186                                 IEEE80211_VHT_CAP_SUPP_CHAN_WIDTH_160MHZ;
 187                 break;
 188         case IEEE80211_VHT_CAP_SUPP_CHAN_WIDTH_160_80PLUS80MHZ:
 189                 vht_cap->cap |= cap_info &
 190                                 IEEE80211_VHT_CAP_SUPP_CHAN_WIDTH_MASK;
 191                 break;
 192         default:
 193                 /* nothing */
 194                 break;
 195         }
 196
 197         /* symmetric capabilities */
 198         vht_cap->cap |= cap_info & own_cap.cap &
 199                         (IEEE80211_VHT_CAP_SHORT_GI_80 |
 200                          IEEE80211_VHT_CAP_SHORT_GI_160);
 201
 202         /* remaining ones */
 203         if (own_cap.cap & IEEE80211_VHT_CAP_SU_BEAMFORMEE_CAPABLE)
 204                 vht_cap->cap |= cap_info &
 205                                 (IEEE80211_VHT_CAP_SU_BEAMFORMER_CAPABLE |
 206                                  IEEE80211_VHT_CAP_SOUNDING_DIMENSIONS_MASK);
 207
 208         if (own_cap.cap & IEEE80211_VHT_CAP_SU_BEAMFORMER_CAPABLE)
 209                 vht_cap->cap |= cap_info &
 210                                 (IEEE80211_VHT_CAP_SU_BEAMFORMEE_CAPABLE |
 211                                  IEEE80211_VHT_CAP_BEAMFORMEE_STS_MASK);
 212
 213         if (own_cap.cap & IEEE80211_VHT_CAP_MU_BEAMFORMER_CAPABLE)
 214                 vht_cap->cap |= cap_info &
 215                                 IEEE80211_VHT_CAP_MU_BEAMFORMEE_CAPABLE;
 216
 217         if (own_cap.cap & IEEE80211_VHT_CAP_MU_BEAMFORMEE_CAPABLE)
 218                 vht_cap->cap |= cap_info &
 219                                 IEEE80211_VHT_CAP_MU_BEAMFORMER_CAPABLE;
 220
 221         if (own_cap.cap & IEEE80211_VHT_CAP_TXSTBC)
 222                 vht_cap->cap |= cap_info & IEEE80211_VHT_CAP_RXSTBC_MASK;
 223
 224         if (own_cap.cap & IEEE80211_VHT_CAP_RXSTBC_MASK)
 225                 vht_cap->cap |= cap_info & IEEE80211_VHT_CAP_TXSTBC;
 226
 227         /* Copy peer MCS info, the driver might need them. */
 228         memcpy(&vht_cap->vht_mcs, &vht_cap_ie->supp_mcs,
 229                sizeof(struct ieee80211_vht_mcs_info));
 230
 231         /* but also restrict MCSes */
 232         for (i = 0; i < 8; i++) {
 233                 u16 own_rx, own_tx, peer_rx, peer_tx;
 234
 235                 own_rx = le16_to_cpu(own_cap.vht_mcs.rx_mcs_map);
 236                 own_rx = (own_rx >> i * 2) & IEEE80211_VHT_MCS_NOT_SUPPORTED;
 237
 238                 own_tx = le16_to_cpu(own_cap.vht_mcs.tx_mcs_map);
 239                 own_tx = (own_tx >> i * 2) & IEEE80211_VHT_MCS_NOT_SUPPORTED;
 240
 241                 peer_rx = le16_to_cpu(vht_cap->vht_mcs.rx_mcs_map);
 242                 peer_rx = (peer_rx >> i * 2) & IEEE80211_VHT_MCS_NOT_SUPPORTED;
 243
 244                 peer_tx = le16_to_cpu(vht_cap->vht_mcs.tx_mcs_map);
 245                 peer_tx = (peer_tx >> i * 2) & IEEE80211_VHT_MCS_NOT_SUPPORTED;
 246
 247                 if (peer_tx != IEEE80211_VHT_MCS_NOT_SUPPORTED) {
 248                         if (own_rx == IEEE80211_VHT_MCS_NOT_SUPPORTED)
 249                                 peer_tx = IEEE80211_VHT_MCS_NOT_SUPPORTED;
 250                         else if (own_rx < peer_tx)
 251                                 peer_tx = own_rx;
 252                 }
 253
 254                 if (peer_rx != IEEE80211_VHT_MCS_NOT_SUPPORTED) {
 255                         if (own_tx == IEEE80211_VHT_MCS_NOT_SUPPORTED)
 256                                 peer_rx = IEEE80211_VHT_MCS_NOT_SUPPORTED;
 257                         else if (own_tx < peer_rx)
 258                                 peer_rx = own_tx;
 259                 }
 260
 261                 vht_cap->vht_mcs.rx_mcs_map &=
 262                         ~cpu_to_le16(IEEE80211_VHT_MCS_NOT_SUPPORTED << i * 2);
 263                 vht_cap->vht_mcs.rx_mcs_map |= cpu_to_le16(peer_rx << i * 2);
 264
 265                 vht_cap->vht_mcs.tx_mcs_map &=
 266                         ~cpu_to_le16(IEEE80211_VHT_MCS_NOT_SUPPORTED << i * 2);
 267                 vht_cap->vht_mcs.tx_mcs_map |= cpu_to_le16(peer_tx << i * 2);
 268         }
 269
 270         /* finally set up the bandwidth */
 271         switch (vht_cap->cap & IEEE80211_VHT_CAP_SUPP_CHAN_WIDTH_MASK) {
 272         case IEEE80211_VHT_CAP_SUPP_CHAN_WIDTH_160MHZ:
 273         case IEEE80211_VHT_CAP_SUPP_CHAN_WIDTH_160_80PLUS80MHZ:
 274                 sta->cur_max_bandwidth = IEEE80211_STA_RX_BW_160;
 275                 break;
 276         default:
 277                 sta->cur_max_bandwidth = IEEE80211_STA_RX_BW_80;
 278         }
 279
 280         sta->sta.bandwidth = ieee80211_sta_cur_vht_bw(sta);
 281 }
 282
 283 enum ieee80211_sta_rx_bandwidth ieee80211_sta_cap_rx_bw(struct sta_info *sta)
 284 {
 285         struct ieee80211_sta_vht_cap *vht_cap = &sta->sta.vht_cap;
 286         u32 cap_width;
 287
 288         if (!vht_cap->vht_supported)
 289                 return sta->sta.ht_cap.cap & IEEE80211_HT_CAP_SUP_WIDTH_20_40 ?
 290                                 IEEE80211_STA_RX_BW_40 :
 291                                 IEEE80211_STA_RX_BW_20;
 292
 293         cap_width = vht_cap->cap & IEEE80211_VHT_CAP_SUPP_CHAN_WIDTH_MASK;
 294
 295         if (cap_width == IEEE80211_VHT_CAP_SUPP_CHAN_WIDTH_160MHZ ||
 296             cap_width == IEEE80211_VHT_CAP_SUPP_CHAN_WIDTH_160_80PLUS80MHZ)
 297                 return IEEE80211_STA_RX_BW_160;
 298
 299         return IEEE80211_STA_RX_BW_80;
 300 }
 301
 302 enum nl80211_chan_width ieee80211_sta_cap_chan_bw(struct sta_info *sta)
 303 {
 304         struct ieee80211_sta_vht_cap *vht_cap = &sta->sta.vht_cap;
 305         u32 cap_width;
 306
 307         if (!vht_cap->vht_supported) {
 308                 if (!sta->sta.ht_cap.ht_supported)
 309                         return NL80211_CHAN_WIDTH_20_NOHT;
 310
 311                 return sta->sta.ht_cap.cap & IEEE80211_HT_CAP_SUP_WIDTH_20_40 ?
 312                                 NL80211_CHAN_WIDTH_40 : NL80211_CHAN_WIDTH_20;
 313         }
 314
 315         cap_width = vht_cap->cap & IEEE80211_VHT_CAP_SUPP_CHAN_WIDTH_MASK;
 316
 317         if (cap_width == IEEE80211_VHT_CAP_SUPP_CHAN_WIDTH_160MHZ)
 318                 return NL80211_CHAN_WIDTH_160;
 319         else if (cap_width == IEEE80211_VHT_CAP_SUPP_CHAN_WIDTH_160_80PLUS80MHZ)
 320                 return NL80211_CHAN_WIDTH_80P80;
 321
 322         return NL80211_CHAN_WIDTH_80;
 323 }
 324
 325 enum ieee80211_sta_rx_bandwidth
 326 ieee80211_chan_width_to_rx_bw(enum nl80211_chan_width width)
 327 {
 328         switch (width) {
 329         case NL80211_CHAN_WIDTH_20_NOHT:
 330         case NL80211_CHAN_WIDTH_20:
 331                 return IEEE80211_STA_RX_BW_20;
 332         case NL80211_CHAN_WIDTH_40:
 333                 return IEEE80211_STA_RX_BW_40;
 334         case NL80211_CHAN_WIDTH_80:
 335                 return IEEE80211_STA_RX_BW_80;
 336         case NL80211_CHAN_WIDTH_160:
 337         case NL80211_CHAN_WIDTH_80P80:
 338                 return IEEE80211_STA_RX_BW_160;
 339         default:
 340                 WARN_ON_ONCE(1);
 341                 return IEEE80211_STA_RX_BW_20;
 342         }
 343 }
 344
 345 enum ieee80211_sta_rx_bandwidth ieee80211_sta_cur_vht_bw(struct sta_info *sta)
 346 {
 347         struct ieee80211_sub_if_data *sdata = sta->sdata;
 348         enum ieee80211_sta_rx_bandwidth bw;
 349         enum nl80211_chan_width bss_width = sdata->vif.bss_conf.chandef.width;
 350
 351         bw = ieee80211_sta_cap_rx_bw(sta);
 352         bw = min(bw, sta->cur_max_bandwidth);
 353         bw = min(bw, ieee80211_chan_width_to_rx_bw(bss_width));
 354
 355         return bw;
 356 }
 357
 358 void ieee80211_sta_set_rx_nss(struct sta_info *sta)
 359 {
 360         u8 ht_rx_nss = 0, vht_rx_nss = 0;
 361
 362         /* if we received a notification already don't overwrite it */
 363         if (sta->sta.rx_nss)
 364                 return;
 365
 366         if (sta->sta.ht_cap.ht_supported) {
 367                 if (sta->sta.ht_cap.mcs.rx_mask[0])
 368                         ht_rx_nss++;
 369                 if (sta->sta.ht_cap.mcs.rx_mask[1])
 370                         ht_rx_nss++;
 371                 if (sta->sta.ht_cap.mcs.rx_mask[2])
 372                         ht_rx_nss++;
 373                 if (sta->sta.ht_cap.mcs.rx_mask[3])
 374                         ht_rx_nss++;
 375                 /* FIXME: consider rx_highest? */
 376         }
 377
 378         if (sta->sta.vht_cap.vht_supported) {
 379                 int i;
 380                 u16 rx_mcs_map;
 381
 382                 rx_mcs_map = le16_to_cpu(sta->sta.vht_cap.vht_mcs.rx_mcs_map);
 383
 384                 for (i = 7; i >= 0; i--) {
 385                         u8 mcs = (rx_mcs_map >> (2 * i)) & 3;
 386
 387                         if (mcs != IEEE80211_VHT_MCS_NOT_SUPPORTED) {
 388                                 vht_rx_nss = i + 1;
 389                                 break;
 390                         }
 391                 }
 392                 /* FIXME: consider rx_highest? */
 393         }
 394
 395         ht_rx_nss = max(ht_rx_nss, vht_rx_nss);
 396         sta->sta.rx_nss = max_t(u8, 1, ht_rx_nss);
 397 }
 398
 399 u32 __ieee80211_vht_handle_opmode(struct ieee80211_sub_if_data *sdata,
 400                                   struct sta_info *sta, u8 opmode,
 401                                   enum ieee80211_band band)
 402 {
 403         struct ieee80211_local *local = sdata->local;
 404         struct ieee80211_supported_band *sband;
 405         enum ieee80211_sta_rx_bandwidth new_bw;
 406         u32 changed = 0;
 407         u8 nss;
 408
 409         sband = local->hw.wiphy->bands[band];
 410
 411         /* ignore - no support for BF yet */
 412         if (opmode & IEEE80211_OPMODE_NOTIF_RX_NSS_TYPE_BF)
 413                 return 0;
 414
 415         nss = opmode & IEEE80211_OPMODE_NOTIF_RX_NSS_MASK;
 416         nss >>= IEEE80211_OPMODE_NOTIF_RX_NSS_SHIFT;
 417         nss += 1;
 418
 419         if (sta->sta.rx_nss != nss) {
 420                 sta->sta.rx_nss = nss;
 421                 changed |= IEEE80211_RC_NSS_CHANGED;
 422         }
 423
 424         switch (opmode & IEEE80211_OPMODE_NOTIF_CHANWIDTH_MASK) {
 425         case IEEE80211_OPMODE_NOTIF_CHANWIDTH_20MHZ:
 426                 sta->cur_max_bandwidth = IEEE80211_STA_RX_BW_20;
 427                 break;
 428         case IEEE80211_OPMODE_NOTIF_CHANWIDTH_40MHZ:
 429                 sta->cur_max_bandwidth = IEEE80211_STA_RX_BW_40;
 430                 break;
 431         case IEEE80211_OPMODE_NOTIF_CHANWIDTH_80MHZ:
 432                 sta->cur_max_bandwidth = IEEE80211_STA_RX_BW_80;
 433                 break;
 434         case IEEE80211_OPMODE_NOTIF_CHANWIDTH_160MHZ:
 435                 sta->cur_max_bandwidth = IEEE80211_STA_RX_BW_160;
 436                 break;
 437         }
 438
 439         new_bw = ieee80211_sta_cur_vht_bw(sta);
 440         if (new_bw != sta->sta.bandwidth) {
 441                 sta->sta.bandwidth = new_bw;
 442                 changed |= IEEE80211_RC_BW_CHANGED;
 443         }
 444
 445         return changed;
 446 }
 447
 448 void ieee80211_vht_handle_opmode(struct ieee80211_sub_if_data *sdata,
 449                                  struct sta_info *sta, u8 opmode,
 450                                  enum ieee80211_band band)
 451 {
 452         struct ieee80211_local *local = sdata->local;
 453         struct ieee80211_supported_band *sband = local->hw.wiphy->bands[band];
 454
 455         u32 changed = __ieee80211_vht_handle_opmode(sdata, sta, opmode, band);
 456
 457         if (changed > 0)
 458                 rate_control_rate_update(local, sband, sta, changed);
 459 }
 460
 461 void ieee80211_get_vht_mask_from_cap(__le16 vht_cap,
 462                                      u16 vht_mask[NL80211_VHT_NSS_MAX])
 463 {
 464         int i;
 465         u16 mask, cap = le16_to_cpu(vht_cap);
 466
 467         for (i = 0; i < NL80211_VHT_NSS_MAX; i++) {
 468                 mask = (cap >> i * 2) & IEEE80211_VHT_MCS_NOT_SUPPORTED;
 469                 switch (mask) {
 470                 case IEEE80211_VHT_MCS_SUPPORT_0_7:
 471                         vht_mask[i] = 0x00FF;
 472                         break;
 473                 case IEEE80211_VHT_MCS_SUPPORT_0_8:
 474                         vht_mask[i] = 0x01FF;
 475                         break;
 476                 case IEEE80211_VHT_MCS_SUPPORT_0_9:
 477                         vht_mask[i] = 0x03FF;
 478                         break;
 479                 case IEEE80211_VHT_MCS_NOT_SUPPORTED:
 480                 default:
 481                         vht_mask[i] = 0;
 482                         break;
 483                 }
 484         }
 485 }