openwrt/package/mac80211/patches/524-mac80211_configure_antenna_gain.patch

--- a/include/net/mac80211.h
+++ b/include/net/mac80211.h
@@ -851,6 +851,7 @@ enum ieee80211_smps_mode {
  *	the CONF_PS flag is set.
  *
  * @power_level: requested transmit power (in dBm)
+ * @max_antenna_gain: maximum antenna gain adjusted by user config (in dBi)
  *
  * @channel: the channel to tune to
  * @channel_type: the channel (HT) type
@@ -870,6 +871,7 @@ struct ieee80211_conf {
 	u32 flags;
 	int power_level, dynamic_ps_timeout;
 	int max_sleep_period;
+	int max_antenna_gain;
 
 	u16 listen_interval;
 	u8 ps_dtim_period;
--- a/net/mac80211/main.c
+++ b/net/mac80211/main.c
@@ -101,7 +101,7 @@ int ieee80211_hw_config(struct ieee80211
 {
 	struct ieee80211_channel *chan;
 	int ret = 0;
-	int power;
+	int power, ant_gain, max_power;
 	enum nl80211_channel_type channel_type;
 	u32 offchannel_flag;
 
@@ -152,19 +152,31 @@ int ieee80211_hw_config(struct ieee80211
 		changed |= IEEE80211_CONF_CHANGE_SMPS;
 	}
 
-	if (test_bit(SCAN_SW_SCANNING, &local->scanning) ||
-	    test_bit(SCAN_ONCHANNEL_SCANNING, &local->scanning) ||
-	    test_bit(SCAN_HW_SCANNING, &local->scanning) ||
-	    !local->ap_power_level)
-		power = chan->max_power;
-	else
-		power = min(chan->max_power, local->ap_power_level);
+	max_power = chan->max_reg_power;
+	if (!test_bit(SCAN_SW_SCANNING, &local->scanning) &&
+	    !test_bit(SCAN_ONCHANNEL_SCANNING, &local->scanning) &&
+	    !test_bit(SCAN_HW_SCANNING, &local->scanning) &&
+	    local->ap_power_level)
+		max_power = min(max_power, local->ap_power_level);
+
+	ant_gain = chan->max_antenna_gain;
+	if (local->user_antenna_gain > 0) {
+		if (local->user_antenna_gain > ant_gain) {
+			max_power -= local->user_antenna_gain - ant_gain;
+			ant_gain = 0;
+		} else
+			ant_gain -= local->user_antenna_gain;
+	}
+
+	power = min(chan->max_power, max_power);
 
 	if (local->user_power_level >= 0)
 		power = min(power, local->user_power_level);
 
-	if (local->hw.conf.power_level != power) {
+	if (local->hw.conf.power_level != power ||
+		local->hw.conf.max_antenna_gain != ant_gain) {
 		changed |= IEEE80211_CONF_CHANGE_POWER;
+		local->hw.conf.max_antenna_gain = ant_gain;
 		local->hw.cur_power_level = power;
 		local->hw.conf.power_level = power;
 	}
@@ -620,6 +632,7 @@ struct ieee80211_hw *ieee80211_alloc_hw(
 					 IEEE80211_RADIOTAP_MCS_HAVE_GI |
 					 IEEE80211_RADIOTAP_MCS_HAVE_BW;
 	local->user_power_level = -1;
+	local->user_antenna_gain = -1;
 	wiphy->ht_capa_mod_mask = &mac80211_ht_capa_mod_mask;
 
 	INIT_LIST_HEAD(&local->interfaces);
--- a/net/mac80211/ieee80211_i.h
+++ b/net/mac80211/ieee80211_i.h
@@ -1063,6 +1063,7 @@ struct ieee80211_local {
 
 	int user_power_level; /* in dBm */
 	int ap_power_level; /* in dBm */
+	int user_antenna_gain; /* in dBi */
 
 	enum ieee80211_smps_mode smps_mode;
 
--- a/include/linux/nl80211.h
+++ b/include/linux/nl80211.h
@@ -1517,6 +1517,8 @@ enum nl80211_attrs {
 
 	NL80211_ATTR_USER_REG_HINT_TYPE,
 
+	NL80211_ATTR_WIPHY_ANTENNA_GAIN,
+
 	/* add attributes here, update the policy in nl80211.c */
 
 	__NL80211_ATTR_AFTER_LAST,
--- a/net/wireless/nl80211.c
+++ b/net/wireless/nl80211.c
@@ -355,6 +355,7 @@ static const struct nla_policy nl80211_p
 	[NL80211_ATTR_BG_SCAN_PERIOD] = { .type = NLA_U16 },
 	[NL80211_ATTR_WDEV] = { .type = NLA_U64 },
 	[NL80211_ATTR_USER_REG_HINT_TYPE] = { .type = NLA_U32 },
+	[NL80211_ATTR_WIPHY_ANTENNA_GAIN] = { .type = NLA_U32 },
 };
 
 /* policy for the key attributes */
@@ -1604,6 +1605,22 @@ static int nl80211_set_wiphy(struct sk_b
 			goto bad_res;
 	}
 
+	if (info->attrs[NL80211_ATTR_WIPHY_ANTENNA_GAIN]) {
+		int idx, dbi = 0;
+
+		if (!rdev->ops->set_antenna_gain) {
+			result = -EOPNOTSUPP;
+			goto bad_res;
+		}
+
+		idx = NL80211_ATTR_WIPHY_ANTENNA_GAIN;
+		dbi = nla_get_u32(info->attrs[idx]);
+
+		result = rdev->ops->set_antenna_gain(&rdev->wiphy, dbi);
+		if (result)
+			goto bad_res;
+	}
+
 	if (info->attrs[NL80211_ATTR_WIPHY_ANTENNA_TX] &&
 	    info->attrs[NL80211_ATTR_WIPHY_ANTENNA_RX]) {
 		u32 tx_ant, rx_ant;
--- a/net/mac80211/cfg.c
+++ b/net/mac80211/cfg.c
@@ -1984,6 +1984,19 @@ static int ieee80211_get_tx_power(struct
 	return 0;
 }
 
+static int ieee80211_set_antenna_gain(struct wiphy *wiphy, int dbi)
+{
+	struct ieee80211_local *local = wiphy_priv(wiphy);
+
+	if (dbi < 0)
+		return -EINVAL;
+
+	local->user_antenna_gain = dbi;
+	ieee80211_hw_config(local, 0);
+
+	return 0;
+}
+
 static int ieee80211_set_wds_peer(struct wiphy *wiphy, struct net_device *dev,
 				  const u8 *addr)
 {
@@ -3082,6 +3095,7 @@ struct cfg80211_ops mac80211_config_ops 
 	.set_wiphy_params = ieee80211_set_wiphy_params,
 	.set_tx_power = ieee80211_set_tx_power,
 	.get_tx_power = ieee80211_get_tx_power,
+	.set_antenna_gain = ieee80211_set_antenna_gain,
 	.set_wds_peer = ieee80211_set_wds_peer,
 	.rfkill_poll = ieee80211_rfkill_poll,
 	CFG80211_TESTMODE_CMD(ieee80211_testmode_cmd)
--- a/include/net/cfg80211.h
+++ b/include/net/cfg80211.h
@@ -1551,6 +1551,7 @@ struct cfg80211_gtk_rekey_data {
  *	the power passed is in mBm, to get dBm use MBM_TO_DBM().
  * @get_tx_power: store the current TX power into the dbm variable;
  *	return 0 if successful
+ * @set_antenna_gain: set antenna gain to reduce maximum tx power if necessary
  *
  * @set_wds_peer: set the WDS peer for a WDS interface
  *
@@ -1750,6 +1751,7 @@ struct cfg80211_ops {
 	int	(*set_tx_power)(struct wiphy *wiphy,
 				enum nl80211_tx_power_setting type, int mbm);
 	int	(*get_tx_power)(struct wiphy *wiphy, int *dbm);
+	int	(*set_antenna_gain)(struct wiphy *wiphy, int dbi);
 
 	int	(*set_wds_peer)(struct wiphy *wiphy, struct net_device *dev,
 				const u8 *addr);