mac80211: support VHT association
authorJohannes Berg <johannes.berg@intel.com>
Thu, 22 Nov 2012 13:11:39 +0000 (14:11 +0100)
committerJohannes Berg <johannes.berg@intel.com>
Tue, 27 Nov 2012 10:56:07 +0000 (11:56 +0100)
Determine the VHT channel from the AP's VHT operation IE
(if present) and configure the hardware to that channel
if it is supported. If channel contexts cause a channel
to not be usable, try a smaller bandwidth.

Signed-off-by: Johannes Berg <johannes.berg@intel.com>
include/linux/ieee80211.h
net/mac80211/ieee80211_i.h
net/mac80211/mlme.c

index f9c5a787d35060f54b459246e099a820ece8b38e..8f690e53dd898a8983e7c192664d6cba922ed536 100644 (file)
@@ -1212,6 +1212,21 @@ struct ieee80211_vht_cap {
        struct ieee80211_vht_mcs_info supp_mcs;
 } __packed;
 
+/**
+ * enum ieee80211_vht_chanwidth - VHT channel width
+ * @IEEE80211_VHT_CHANWIDTH_USE_HT: use the HT operation IE to
+ *     determine the channel width (20 or 40 MHz)
+ * @IEEE80211_VHT_CHANWIDTH_80MHZ: 80 MHz bandwidth
+ * @IEEE80211_VHT_CHANWIDTH_160MHZ: 160 MHz bandwidth
+ * @IEEE80211_VHT_CHANWIDTH_80P80MHZ: 80+80 MHz bandwidth
+ */
+enum ieee80211_vht_chanwidth {
+       IEEE80211_VHT_CHANWIDTH_USE_HT          = 0,
+       IEEE80211_VHT_CHANWIDTH_80MHZ           = 1,
+       IEEE80211_VHT_CHANWIDTH_160MHZ          = 2,
+       IEEE80211_VHT_CHANWIDTH_80P80MHZ        = 3,
+};
+
 /**
  * struct ieee80211_vht_operation - VHT operation IE
  *
index 0a8f83d142f906fdf15b2c142749ab52be93b5a5..8d8bf7136386402d93a7c8a4ed1fe9a6cc24cc79 100644 (file)
@@ -371,6 +371,8 @@ enum ieee80211_sta_flags {
        IEEE80211_STA_RESET_SIGNAL_AVE  = BIT(9),
        IEEE80211_STA_DISABLE_40MHZ     = BIT(10),
        IEEE80211_STA_DISABLE_VHT       = BIT(11),
+       IEEE80211_STA_DISABLE_80P80MHZ  = BIT(12),
+       IEEE80211_STA_DISABLE_160MHZ    = BIT(13),
 };
 
 struct ieee80211_mgd_auth_data {
index d2a4f78b4b0f658e44022d8cd6fe2b80cbff591e..35d8cffc973ac20b68765093530592e9fe70bb7c 100644 (file)
@@ -354,6 +354,16 @@ static void ieee80211_add_vht_ie(struct ieee80211_sub_if_data *sdata,
        /* determine capability flags */
        cap = vht_cap.cap;
 
+       if (sdata->u.mgd.flags & IEEE80211_STA_DISABLE_80P80MHZ) {
+               cap &= ~IEEE80211_VHT_CAP_SUPP_CHAN_WIDTH_160_80PLUS80MHZ;
+               cap |= IEEE80211_VHT_CAP_SUPP_CHAN_WIDTH_160MHZ;
+       }
+
+       if (sdata->u.mgd.flags & IEEE80211_STA_DISABLE_160MHZ) {
+               cap &= ~IEEE80211_VHT_CAP_SHORT_GI_160;
+               cap &= ~IEEE80211_VHT_CAP_SUPP_CHAN_WIDTH_160MHZ;
+       }
+
        /* reserve and fill IE */
        pos = skb_put(skb, sizeof(struct ieee80211_vht_cap) + 2);
        ieee80211_ie_build_vht_cap(pos, &vht_cap, cap);
@@ -543,6 +553,10 @@ static void ieee80211_send_assoc(struct ieee80211_sub_if_data *sdata)
                offset = noffset;
        }
 
+       if (WARN_ON_ONCE((ifmgd->flags & IEEE80211_STA_DISABLE_HT) &&
+                        !(ifmgd->flags & IEEE80211_STA_DISABLE_VHT)))
+               ifmgd->flags |= IEEE80211_STA_DISABLE_VHT;
+
        if (!(ifmgd->flags & IEEE80211_STA_DISABLE_HT))
                ieee80211_add_ht_ie(sdata, skb, assoc_data->ap_ht_param,
                                    sband, chan, sdata->smps_mode);
@@ -3183,23 +3197,270 @@ int ieee80211_max_network_latency(struct notifier_block *nb,
        return 0;
 }
 
+static u32 chandef_downgrade(struct cfg80211_chan_def *c)
+{
+       u32 ret;
+       int tmp;
+
+       switch (c->width) {
+       case NL80211_CHAN_WIDTH_20:
+               c->width = NL80211_CHAN_WIDTH_20_NOHT;
+               ret = IEEE80211_STA_DISABLE_HT | IEEE80211_STA_DISABLE_VHT;
+               break;
+       case NL80211_CHAN_WIDTH_40:
+               c->width = NL80211_CHAN_WIDTH_20;
+               c->center_freq1 = c->chan->center_freq;
+               ret = IEEE80211_STA_DISABLE_40MHZ |
+                     IEEE80211_STA_DISABLE_VHT;
+               break;
+       case NL80211_CHAN_WIDTH_80:
+               tmp = (30 + c->chan->center_freq - c->center_freq1)/20;
+               /* n_P40 */
+               tmp /= 2;
+               /* freq_P40 */
+               c->center_freq1 = c->center_freq1 - 20 + 40 * tmp;
+               c->width = NL80211_CHAN_WIDTH_40;
+               ret = IEEE80211_STA_DISABLE_VHT;
+               break;
+       case NL80211_CHAN_WIDTH_80P80:
+               c->center_freq2 = 0;
+               c->width = NL80211_CHAN_WIDTH_80;
+               ret = IEEE80211_STA_DISABLE_80P80MHZ |
+                     IEEE80211_STA_DISABLE_160MHZ;
+               break;
+       case NL80211_CHAN_WIDTH_160:
+               /* n_P20 */
+               tmp = (70 + c->chan->center_freq - c->center_freq1)/20;
+               /* n_P80 */
+               tmp /= 4;
+               c->center_freq1 = c->center_freq1 - 40 + 80 * tmp;
+               c->width = NL80211_CHAN_WIDTH_80;
+               ret = IEEE80211_STA_DISABLE_80P80MHZ |
+                     IEEE80211_STA_DISABLE_160MHZ;
+               break;
+       default:
+       case NL80211_CHAN_WIDTH_20_NOHT:
+               WARN_ON_ONCE(1);
+               c->width = NL80211_CHAN_WIDTH_20_NOHT;
+               ret = IEEE80211_STA_DISABLE_HT | IEEE80211_STA_DISABLE_VHT;
+               break;
+       }
+
+       WARN_ON_ONCE(!cfg80211_chandef_valid(c));
+
+       return ret;
+}
+
+static u32
+ieee80211_determine_chantype(struct ieee80211_sub_if_data *sdata,
+                            struct ieee80211_supported_band *sband,
+                            struct ieee80211_channel *channel,
+                            const struct ieee80211_ht_operation *ht_oper,
+                            const struct ieee80211_vht_operation *vht_oper,
+                            struct cfg80211_chan_def *chandef)
+{
+       struct cfg80211_chan_def vht_chandef;
+       u32 ht_cfreq, ret;
+
+       chandef->chan = channel;
+       chandef->width = NL80211_CHAN_WIDTH_20_NOHT;
+       chandef->center_freq1 = channel->center_freq;
+       chandef->center_freq2 = 0;
+
+       if (!ht_oper || !sband->ht_cap.ht_supported) {
+               ret = IEEE80211_STA_DISABLE_HT | IEEE80211_STA_DISABLE_VHT;
+               goto out;
+       }
+
+       chandef->width = NL80211_CHAN_WIDTH_20;
+
+       ht_cfreq = ieee80211_channel_to_frequency(ht_oper->primary_chan,
+                                                 channel->band);
+       /* check that channel matches the right operating channel */
+       if (channel->center_freq != ht_cfreq) {
+               /*
+                * It's possible that some APs are confused here;
+                * Netgear WNDR3700 sometimes reports 4 higher than
+                * the actual channel in association responses, but
+                * since we look at probe response/beacon data here
+                * it should be OK.
+                */
+               sdata_info(sdata,
+                          "Wrong control channel: center-freq: %d ht-cfreq: %d ht->primary_chan: %d band: %d - Disabling HT\n",
+                          channel->center_freq, ht_cfreq,
+                          ht_oper->primary_chan, channel->band);
+               ret = IEEE80211_STA_DISABLE_HT | IEEE80211_STA_DISABLE_VHT;
+               goto out;
+       }
+
+       /* check 40 MHz support, if we have it */
+       if (sband->ht_cap.cap & IEEE80211_HT_CAP_SUP_WIDTH_20_40) {
+               switch (ht_oper->ht_param & IEEE80211_HT_PARAM_CHA_SEC_OFFSET) {
+               case IEEE80211_HT_PARAM_CHA_SEC_ABOVE:
+                       chandef->width = NL80211_CHAN_WIDTH_40;
+                       chandef->center_freq1 += 10;
+                       break;
+               case IEEE80211_HT_PARAM_CHA_SEC_BELOW:
+                       chandef->width = NL80211_CHAN_WIDTH_40;
+                       chandef->center_freq1 -= 10;
+                       break;
+               }
+       } else {
+               /* 40 MHz (and 80 MHz) must be supported for VHT */
+               ret = IEEE80211_STA_DISABLE_VHT;
+               goto out;
+       }
+
+       if (!vht_oper || !sband->vht_cap.vht_supported) {
+               ret = IEEE80211_STA_DISABLE_VHT;
+               goto out;
+       }
+
+       vht_chandef.chan = channel;
+       vht_chandef.center_freq1 =
+               ieee80211_channel_to_frequency(vht_oper->center_freq_seg1_idx,
+                                              channel->band);
+       vht_chandef.center_freq2 = 0;
+
+       if (vht_oper->center_freq_seg2_idx)
+               vht_chandef.center_freq2 =
+                       ieee80211_channel_to_frequency(
+                               vht_oper->center_freq_seg2_idx,
+                               channel->band);
+
+       switch (vht_oper->chan_width) {
+       case IEEE80211_VHT_CHANWIDTH_USE_HT:
+               vht_chandef.width = chandef->width;
+               break;
+       case IEEE80211_VHT_CHANWIDTH_80MHZ:
+               vht_chandef.width = NL80211_CHAN_WIDTH_80;
+               break;
+       case IEEE80211_VHT_CHANWIDTH_160MHZ:
+               vht_chandef.width = NL80211_CHAN_WIDTH_160;
+               break;
+       case IEEE80211_VHT_CHANWIDTH_80P80MHZ:
+               vht_chandef.width = NL80211_CHAN_WIDTH_80P80;
+               break;
+       default:
+               sdata_info(sdata,
+                          "AP VHT operation IE has invalid channel width (%d), disable VHT\n",
+                          vht_oper->chan_width);
+               ret = IEEE80211_STA_DISABLE_VHT;
+               goto out;
+       }
+
+       if (!cfg80211_chandef_valid(&vht_chandef)) {
+               sdata_info(sdata,
+                          "AP VHT information is invalid, disable VHT\n");
+               ret = IEEE80211_STA_DISABLE_VHT;
+               goto out;
+       }
+
+       if (cfg80211_chandef_identical(chandef, &vht_chandef)) {
+               ret = 0;
+               goto out;
+       }
+
+       if (!cfg80211_chandef_compatible(chandef, &vht_chandef)) {
+               sdata_info(sdata,
+                          "AP VHT information doesn't match HT, disable VHT\n");
+               ret = IEEE80211_STA_DISABLE_VHT;
+               goto out;
+       }
+
+       *chandef = vht_chandef;
+
+       ret = 0;
+
+       while (!cfg80211_chandef_usable(sdata->local->hw.wiphy, chandef,
+                                       IEEE80211_CHAN_DISABLED)) {
+               if (WARN_ON(chandef->width == NL80211_CHAN_WIDTH_20_NOHT)) {
+                       ret = IEEE80211_STA_DISABLE_HT |
+                             IEEE80211_STA_DISABLE_VHT;
+                       goto out;
+               }
+
+               ret = chandef_downgrade(chandef);
+       }
+
+       if (chandef->width != vht_chandef.width)
+               sdata_info(sdata,
+                          "local regulatory prevented using AP HT/VHT configuration, downgraded\n");
+
+out:
+       WARN_ON_ONCE(!cfg80211_chandef_valid(chandef));
+       return ret;
+}
+
+static u8 ieee80211_ht_vht_rx_chains(struct ieee80211_sub_if_data *sdata,
+                                    struct cfg80211_bss *cbss)
+{
+       struct ieee80211_if_managed *ifmgd = &sdata->u.mgd;
+       const u8 *ht_cap_ie, *vht_cap_ie;
+       const struct ieee80211_ht_cap *ht_cap;
+       const struct ieee80211_vht_cap *vht_cap;
+       u8 chains = 1;
+
+       if (ifmgd->flags & IEEE80211_STA_DISABLE_HT)
+               return chains;
+
+       ht_cap_ie = cfg80211_find_ie(WLAN_EID_HT_CAPABILITY,
+                                    cbss->information_elements,
+                                    cbss->len_information_elements);
+       if (ht_cap_ie && ht_cap_ie[1] >= sizeof(*ht_cap)) {
+               ht_cap = (void *)(ht_cap_ie + 2);
+               chains = ieee80211_mcs_to_chains(&ht_cap->mcs);
+               /*
+                * TODO: use "Tx Maximum Number Spatial Streams Supported" and
+                *       "Tx Unequal Modulation Supported" fields.
+                */
+       }
+
+       if (ifmgd->flags & IEEE80211_STA_DISABLE_VHT)
+               return chains;
+
+       vht_cap_ie = cfg80211_find_ie(WLAN_EID_VHT_CAPABILITY,
+                                     cbss->information_elements,
+                                     cbss->len_information_elements);
+       if (vht_cap_ie && vht_cap_ie[1] >= sizeof(*vht_cap)) {
+               u8 nss;
+               u16 tx_mcs_map;
+
+               vht_cap = (void *)(vht_cap_ie + 2);
+               tx_mcs_map = le16_to_cpu(vht_cap->supp_mcs.tx_mcs_map);
+               for (nss = 8; nss > 0; nss--) {
+                       if (((tx_mcs_map >> (2 * (nss - 1))) & 3) !=
+                                       IEEE80211_VHT_MCS_NOT_SUPPORTED)
+                               break;
+               }
+               /* TODO: use "Tx Highest Supported Long GI Data Rate" field? */
+               chains = max(chains, nss);
+       }
+
+       return chains;
+}
+
 static int ieee80211_prep_channel(struct ieee80211_sub_if_data *sdata,
                                  struct cfg80211_bss *cbss)
 {
        struct ieee80211_local *local = sdata->local;
        struct ieee80211_if_managed *ifmgd = &sdata->u.mgd;
-       int ht_cfreq;
-       enum nl80211_channel_type channel_type = NL80211_CHAN_NO_HT;
-       const u8 *ht_oper_ie;
        const struct ieee80211_ht_operation *ht_oper = NULL;
+       const struct ieee80211_vht_operation *vht_oper = NULL;
        struct ieee80211_supported_band *sband;
        struct cfg80211_chan_def chandef;
+       int ret;
 
        sband = local->hw.wiphy->bands[cbss->channel->band];
 
-       ifmgd->flags &= ~IEEE80211_STA_DISABLE_40MHZ;
+       ifmgd->flags &= ~(IEEE80211_STA_DISABLE_40MHZ |
+                         IEEE80211_STA_DISABLE_80P80MHZ |
+                         IEEE80211_STA_DISABLE_160MHZ);
+
+       if (!(ifmgd->flags & IEEE80211_STA_DISABLE_HT) &&
+           sband->ht_cap.ht_supported) {
+               const u8 *ht_oper_ie;
 
-       if (sband->ht_cap.ht_supported) {
                ht_oper_ie = cfg80211_find_ie(WLAN_EID_HT_OPERATION,
                                              cbss->information_elements,
                                              cbss->len_information_elements);
@@ -3207,82 +3468,45 @@ static int ieee80211_prep_channel(struct ieee80211_sub_if_data *sdata,
                        ht_oper = (void *)(ht_oper_ie + 2);
        }
 
-       if (ht_oper) {
-               ht_cfreq = ieee80211_channel_to_frequency(ht_oper->primary_chan,
-                                                         cbss->channel->band);
-               /* check that channel matches the right operating channel */
-               if (cbss->channel->center_freq != ht_cfreq) {
-                       /*
-                        * It's possible that some APs are confused here;
-                        * Netgear WNDR3700 sometimes reports 4 higher than
-                        * the actual channel in association responses, but
-                        * since we look at probe response/beacon data here
-                        * it should be OK.
-                        */
+       if (!(ifmgd->flags & IEEE80211_STA_DISABLE_VHT) &&
+           sband->vht_cap.vht_supported) {
+               const u8 *vht_oper_ie;
+
+               vht_oper_ie = cfg80211_find_ie(WLAN_EID_VHT_OPERATION,
+                                              cbss->information_elements,
+                                              cbss->len_information_elements);
+               if (vht_oper_ie && vht_oper_ie[1] >= sizeof(*vht_oper))
+                       vht_oper = (void *)(vht_oper_ie + 2);
+               if (vht_oper && !ht_oper) {
+                       vht_oper = NULL;
                        sdata_info(sdata,
-                                  "Wrong control channel: center-freq: %d ht-cfreq: %d ht->primary_chan: %d band: %d - Disabling HT\n",
-                                  cbss->channel->center_freq,
-                                  ht_cfreq, ht_oper->primary_chan,
-                                  cbss->channel->band);
-                       ht_oper = NULL;
+                                  "AP advertised VHT without HT, disabling both\n");
+                       sdata->flags |= IEEE80211_STA_DISABLE_HT;
+                       sdata->flags |= IEEE80211_STA_DISABLE_VHT;
                }
        }
 
-       if (ht_oper) {
-               /*
-                * cfg80211 already verified that the channel itself can
-                * be used, but it didn't check that we can do the right
-                * HT type, so do that here as well. If HT40 isn't allowed
-                * on this channel, disable 40 MHz operation.
-                */
-               const u8 *ht_cap_ie;
-               const struct ieee80211_ht_cap *ht_cap;
-               u8 chains = 1;
-
-               channel_type = NL80211_CHAN_HT20;
-
-               if (sband->ht_cap.cap & IEEE80211_HT_CAP_SUP_WIDTH_20_40) {
-                       switch (ht_oper->ht_param &
-                                       IEEE80211_HT_PARAM_CHA_SEC_OFFSET) {
-                       case IEEE80211_HT_PARAM_CHA_SEC_ABOVE:
-                               if (cbss->channel->flags &
-                                               IEEE80211_CHAN_NO_HT40PLUS)
-                                       ifmgd->flags |=
-                                               IEEE80211_STA_DISABLE_40MHZ;
-                               else
-                                       channel_type = NL80211_CHAN_HT40PLUS;
-                               break;
-                       case IEEE80211_HT_PARAM_CHA_SEC_BELOW:
-                               if (cbss->channel->flags &
-                                               IEEE80211_CHAN_NO_HT40MINUS)
-                                       ifmgd->flags |=
-                                               IEEE80211_STA_DISABLE_40MHZ;
-                               else
-                                       channel_type = NL80211_CHAN_HT40MINUS;
-                               break;
-                       }
-               }
+       ifmgd->flags |= ieee80211_determine_chantype(sdata, sband,
+                                                    cbss->channel,
+                                                    ht_oper, vht_oper,
+                                                    &chandef);
 
-               ht_cap_ie = cfg80211_find_ie(WLAN_EID_HT_CAPABILITY,
-                                            cbss->information_elements,
-                                            cbss->len_information_elements);
-               if (ht_cap_ie && ht_cap_ie[1] >= sizeof(*ht_cap)) {
-                       ht_cap = (void *)(ht_cap_ie + 2);
-                       chains = ieee80211_mcs_to_chains(&ht_cap->mcs);
-               }
-               sdata->needed_rx_chains = min(chains, local->rx_chains);
-       } else {
-               sdata->needed_rx_chains = 1;
-               sdata->u.mgd.flags |= IEEE80211_STA_DISABLE_HT;
-       }
+       sdata->needed_rx_chains = min(ieee80211_ht_vht_rx_chains(sdata, cbss),
+                                     local->rx_chains);
 
        /* will change later if needed */
        sdata->smps_mode = IEEE80211_SMPS_OFF;
 
-       ieee80211_vif_release_channel(sdata);
-       cfg80211_chandef_create(&chandef, cbss->channel, channel_type);
-       return ieee80211_vif_use_channel(sdata, &chandef,
-                                        IEEE80211_CHANCTX_SHARED);
+       /*
+        * If this fails (possibly due to channel context sharing
+        * on incompatible channels, e.g. 80+80 and 160 sharing the
+        * same control channel) try to use a smaller bandwidth.
+        */
+       ret = ieee80211_vif_use_channel(sdata, &chandef,
+                                       IEEE80211_CHANCTX_SHARED);
+       while (ret && chandef.width != NL80211_CHAN_WIDTH_20_NOHT)
+               ifmgd->flags |= chandef_downgrade(&chandef);
+       return ret;
 }
 
 static int ieee80211_prep_connection(struct ieee80211_sub_if_data *sdata,