hostapd: Add Transmit Power Envelope IE when VHT is enabled

Add Transmit Power Envelope element defined in IEEE P802.11-REVmc/D4.3,
8.4.2.161.

Signed-off-by: Rajkumar Manoharan <rmanohar@qti.qualcomm.com>

diff --git a/src/ap/beacon.c b/src/ap/beacon.c
index 5f65b7d..9490e21 100644 (file)
--- a/src/ap/beacon.c
+++ b/src/ap/beacon.c
@@ -481,6 +481,7 @@ static u8 * hostapd_gen_probe_resp(struct hostapd_data *hapd,
        if (hapd->iconf->ieee80211ac && !hapd->conf->disable_11ac) {
                pos = hostapd_eid_vht_capabilities(hapd, pos);
                pos = hostapd_eid_vht_operation(hapd, pos);
+               pos = hostapd_eid_txpower_envelope(hapd, pos);
                pos = hostapd_eid_wb_chsw_wrapper(hapd, pos);
        }
        if (hapd->conf->vendor_vht)
@@ -1096,6 +1097,7 @@ int ieee802_11_build_ap_params(struct hostapd_data *hapd,
        if (hapd->iconf->ieee80211ac && !hapd->conf->disable_11ac) {
                tailpos = hostapd_eid_vht_capabilities(hapd, tailpos);
                tailpos = hostapd_eid_vht_operation(hapd, tailpos);
+               tailpos = hostapd_eid_txpower_envelope(hapd, tailpos);
                tailpos = hostapd_eid_wb_chsw_wrapper(hapd, tailpos);
        }
        if (hapd->conf->vendor_vht)

diff --git a/src/ap/ieee802_11.h b/src/ap/ieee802_11.h
index a2dd132..0020ff5 100644 (file)
--- a/src/ap/ieee802_11.h
+++ b/src/ap/ieee802_11.h
@@ -54,6 +54,7 @@ u8 * hostapd_eid_vht_capabilities(struct hostapd_data *hapd, u8 *eid);
 u8 * hostapd_eid_vht_operation(struct hostapd_data *hapd, u8 *eid);
 u8 * hostapd_eid_vendor_vht(struct hostapd_data *hapd, u8 *eid);
 u8 * hostapd_eid_wb_chsw_wrapper(struct hostapd_data *hapd, u8 *eid);
+u8 * hostapd_eid_txpower_envelope(struct hostapd_data *hapd, u8 *eid);
 
 int hostapd_ht_operation_update(struct hostapd_iface *iface);
 void ieee802_11_send_sa_query_req(struct hostapd_data *hapd,

diff --git a/src/ap/ieee802_11_vht.c b/src/ap/ieee802_11_vht.c
index 8d2c428..3236016 100644 (file)
--- a/src/ap/ieee802_11_vht.c
+++ b/src/ap/ieee802_11_vht.c
@@ -17,6 +17,7 @@
 #include "sta_info.h"
 #include "beacon.h"
 #include "ieee802_11.h"
+#include "dfs.h"
 
 
 u8 * hostapd_eid_vht_capabilities(struct hostapd_data *hapd, u8 *eid)
@@ -184,6 +185,118 @@ u8 * hostapd_eid_wb_chsw_wrapper(struct hostapd_data *hapd, u8 *eid)
 }
 
 
+u8 * hostapd_eid_txpower_envelope(struct hostapd_data *hapd, u8 *eid)
+{
+       struct hostapd_iface *iface = hapd->iface;
+       struct hostapd_config *iconf = iface->conf;
+       struct hostapd_hw_modes *mode = iface->current_mode;
+       struct hostapd_channel_data *chan;
+       int dfs, i;
+       u8 channel, tx_pwr_count, local_pwr_constraint;
+       int max_tx_power;
+       u8 tx_pwr;
+
+       if (!mode)
+               return eid;
+
+       if (ieee80211_freq_to_chan(iface->freq, &channel) == NUM_HOSTAPD_MODES)
+               return eid;
+
+       for (i = 0; i < mode->num_channels; i++) {
+               if (mode->channels[i].freq == iface->freq)
+                       break;
+       }
+       if (i == mode->num_channels)
+               return eid;
+
+       switch (iface->conf->vht_oper_chwidth) {
+       case VHT_CHANWIDTH_USE_HT:
+               if (iconf->secondary_channel == 0) {
+                       /* Max Transmit Power count = 0 (20 MHz) */
+                       tx_pwr_count = 0;
+               } else {
+                       /* Max Transmit Power count = 1 (20, 40 MHz) */
+                       tx_pwr_count = 1;
+               }
+               break;
+       case VHT_CHANWIDTH_80MHZ:
+               /* Max Transmit Power count = 2 (20, 40, and 80 MHz) */
+               tx_pwr_count = 2;
+               break;
+       case VHT_CHANWIDTH_80P80MHZ:
+       case VHT_CHANWIDTH_160MHZ:
+               /* Max Transmit Power count = 3 (20, 40, 80, 160/80+80 MHz) */
+               tx_pwr_count = 3;
+               break;
+       default:
+               return eid;
+       }
+
+       /*
+        * Below local_pwr_constraint logic is referred from
+        * hostapd_eid_pwr_constraint.
+        *
+        * Check if DFS is required by regulatory.
+        */
+       dfs = hostapd_is_dfs_required(hapd->iface);
+       if (dfs < 0)
+               dfs = 0;
+
+       /*
+        * In order to meet regulations when TPC is not implemented using
+        * a transmit power that is below the legal maximum (including any
+        * mitigation factor) should help. In this case, indicate 3 dB below
+        * maximum allowed transmit power.
+        */
+       if (hapd->iconf->local_pwr_constraint == -1)
+               local_pwr_constraint = (dfs == 0) ? 0 : 3;
+       else
+               local_pwr_constraint = hapd->iconf->local_pwr_constraint;
+
+       /*
+        * A STA that is not an AP shall use a transmit power less than or
+        * equal to the local maximum transmit power level for the channel.
+        * The local maximum transmit power can be calculated from the formula:
+        * local max TX pwr = max TX pwr - local pwr constraint
+        * Where max TX pwr is maximum transmit power level specified for
+        * channel in Country element and local pwr constraint is specified
+        * for channel in this Power Constraint element.
+        */
+       chan = &mode->channels[i];
+       max_tx_power = chan->max_tx_power - local_pwr_constraint;
+
+       /*
+        * Local Maximum Transmit power is encoded as two's complement
+        * with a 0.5 dB step.
+        */
+       max_tx_power *= 2; /* in 0.5 dB steps */
+       if (max_tx_power > 127) {
+               /* 63.5 has special meaning of 63.5 dBm or higher */
+               max_tx_power = 127;
+       }
+       if (max_tx_power < -128)
+               max_tx_power = -128;
+       if (max_tx_power < 0)
+               tx_pwr = 0x80 + max_tx_power + 128;
+       else
+               tx_pwr = max_tx_power;
+
+       *eid++ = WLAN_EID_VHT_TRANSMIT_POWER_ENVELOPE;
+       *eid++ = 2 + tx_pwr_count;
+
+       /*
+        * Max Transmit Power count and
+        * Max Transmit Power units = 0 (EIRP)
+        */
+       *eid++ = tx_pwr_count;
+
+       for (i = 0; i <= tx_pwr_count; i++)
+               *eid++ = tx_pwr;
+
+       return eid;
+}
+
+
 u16 copy_sta_vht_capab(struct hostapd_data *hapd, struct sta_info *sta,
                       const u8 *vht_capab)
 {