[RFC] mac80211: Handle power constraint level advertised in 11d+h beacon

[Vasanthakumar Thiagarajan <vasanth@atheros.com>]

This patch uses power constraint level while determining the maximum
transmit power, there by it makes sure that any power mitigation
requirement for the channel in the current regulatory domain is met.

Signed-off-by: Vasanthakumar Thiagarajan <vasanth@atheros.com>
---
 include/net/mac80211.h     |    2 ++
 net/mac80211/ieee80211_i.h |    3 +++
 net/mac80211/main.c        |   10 ++++++++--
 net/mac80211/mlme.c        |   20 +++++++++++++++++++-
 net/mac80211/spectmgmt.c   |   22 ++++++++++++++++++++++
 5 files changed, 54 insertions(+), 3 deletions(-)

diff --git a/include/net/mac80211.h b/include/net/mac80211.h
index 153a8d1..a1126d3 100644
--- a/include/net/mac80211.h
+++ b/include/net/mac80211.h
@@ -549,6 +549,7 @@ enum ieee80211_conf_changed {
  * @flags: configuration flags defined above
  * @power_level: requested transmit power (in dBm)
  * @user_power_level: User configured transmit power (in dBm)
+ * @power_constr_level: Power constraint level advertised in 11h beacon (in dBm)
  * @channel: the channel to tune to
  * @ht: the HT configuration for the device
  * @long_frame_max_tx_count: Maximum number of transmissions for a "long" frame
@@ -563,6 +564,7 @@ struct ieee80211_conf {
 	u32 flags;
 	int power_level;
 	int user_power_level;
+	int power_constr_level;
 
 	u16 listen_interval;
 	bool radio_enabled;
diff --git a/net/mac80211/ieee80211_i.h b/net/mac80211/ieee80211_i.h
index 117718b..1abe96e 100644
--- a/net/mac80211/ieee80211_i.h
+++ b/net/mac80211/ieee80211_i.h
@@ -964,6 +964,9 @@ void ieee80211_process_addba_request(struct ieee80211_local *local,
 void ieee80211_process_measurement_req(struct ieee80211_sub_if_data *sdata,
 				       struct ieee80211_mgmt *mgmt,
 				       size_t len);
+void ieee80211_handle_pwr_constr(struct ieee80211_sub_if_data *sdata,
+				 u16 capab_info, u8 *pwr_constr_elem,
+				 u8 pwr_constr_elem_len);
 
 /* utility functions/constants */
 extern void *mac80211_wiphy_privid; /* for wiphy privid */
diff --git a/net/mac80211/main.c b/net/mac80211/main.c
index 8831e87..66108f6 100644
--- a/net/mac80211/main.c
+++ b/net/mac80211/main.c
@@ -224,10 +224,16 @@ int ieee80211_hw_config(struct ieee80211_local *local, u32 changed)
 		changed |= IEEE80211_CONF_CHANGE_CHANNEL;
 	}
 
-	if (!local->hw.conf.user_power_level)
+	if (local->sw_scanning)
 		power = chan->max_power;
 	else
-		power = min(chan->max_power, local->hw.conf.user_power_level);
+		power = local->hw.conf.power_constr_level ?
+			(chan->max_power - local->hw.conf.power_constr_level) :
+			chan->max_power;
+
+	if (local->hw.conf.user_power_level)
+		power = min(power, local->hw.conf.user_power_level);
+
 	if (local->hw.conf.power_level != power) {
 		changed |= IEEE80211_CONF_CHANGE_POWER;
 		local->hw.conf.power_level = power;
diff --git a/net/mac80211/mlme.c b/net/mac80211/mlme.c
index e317c6d..f193ba4 100644
--- a/net/mac80211/mlme.c
+++ b/net/mac80211/mlme.c
@@ -911,6 +911,8 @@ static void ieee80211_set_disassoc(struct ieee80211_sub_if_data *sdata,
 	local->oper_channel_type = NL80211_CHAN_NO_HT;
 	config_changed |= IEEE80211_CONF_CHANGE_HT;
 
+	local->hw.conf.power_constr_level = 0;
+
 	del_timer_sync(&local->dynamic_ps_timer);
 	cancel_work_sync(&local->dynamic_ps_enable_work);
 
@@ -1719,7 +1721,6 @@ static void ieee80211_rx_bss_info(struct ieee80211_sub_if_data *sdata,
 	ieee80211_rx_bss_put(local, bss);
 }
 
-
 static void ieee80211_rx_mgmt_probe_resp(struct ieee80211_sub_if_data *sdata,
 					 struct ieee80211_mgmt *mgmt,
 					 size_t len,
@@ -1748,6 +1749,16 @@ static void ieee80211_rx_mgmt_probe_resp(struct ieee80211_sub_if_data *sdata,
 		       sdata->dev->name);
 		ieee80211_authenticate(sdata, ifsta);
 	}
+
+	/* TODO: for IBSS */
+	if ((sdata->vif.type == NL80211_IFTYPE_STATION) &&
+	    (ifsta->flags & IEEE80211_STA_ASSOCIATED) &&
+	    (memcmp(ifsta->bssid, mgmt->bssid, ETH_ALEN) == 0) &&
+	    elems.pwr_constr_elem)
+		ieee80211_handle_pwr_constr(sdata,
+				le16_to_cpu(mgmt->u.probe_resp.capab_info),
+				elems.pwr_constr_elem,
+				elems.pwr_constr_elem_len);
 }
 
 
@@ -1841,6 +1852,13 @@ static void ieee80211_rx_mgmt_beacon(struct ieee80211_sub_if_data *sdata,
 			elems.country_elem, elems.country_elem_len);
 	}
 
+	/* TODO: IBSS also needs this */
+	if (elems.pwr_constr_elem)
+		ieee80211_handle_pwr_constr(sdata,
+				le16_to_cpu(mgmt->u.probe_resp.capab_info),
+				elems.pwr_constr_elem,
+				elems.pwr_constr_elem_len);
+
 	ieee80211_bss_info_change_notify(sdata, changed);
 }
 
diff --git a/net/mac80211/spectmgmt.c b/net/mac80211/spectmgmt.c
index f72bad6..f7ffec1 100644
--- a/net/mac80211/spectmgmt.c
+++ b/net/mac80211/spectmgmt.c
@@ -84,3 +84,25 @@ void ieee80211_process_measurement_req(struct ieee80211_sub_if_data *sdata,
 			mgmt->sa, mgmt->bssid,
 			mgmt->u.action.u.measurement.dialog_token);
 }
+
+void ieee80211_handle_pwr_constr(struct ieee80211_sub_if_data *sdata,
+				 u16 capab_info, u8 *pwr_constr_elem,
+				 u8 pwr_constr_elem_len)
+{
+	struct ieee80211_conf *conf = &sdata->local->hw.conf;
+
+	if ((conf->channel->band != IEEE80211_BAND_5GHZ) ||
+	    !(capab_info & WLAN_CAPABILITY_SPECTRUM_MGMT))
+		return;
+
+	/* Power constraint IE length should be 1 octet */
+	if (pwr_constr_elem_len != 1)
+		return;
+
+	if ((*pwr_constr_elem <= conf->channel->max_power) &&
+	    (*pwr_constr_elem != conf->power_constr_level)) {
+		conf->power_constr_level = *pwr_constr_elem;
+		ieee80211_hw_config(sdata->local, 0);
+	}
+}
+
-- 
1.5.5.1