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

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>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

4 files changed, 42 insertions, 2 deletions

diff --git a/net/mac80211/ieee80211_i.h b/net/mac80211/ieee80211_i.h
index 9112c52..c9ffadb 100644
--- a/net/mac80211/ieee80211_i.h
+++ b/net/mac80211/ieee80211_i.h
@@ -715,6 +715,7 @@ struct ieee80211_local {
 	struct timer_list dynamic_ps_timer;
 
 	int user_power_level; /* in dBm */
+	int power_constr_level; /* in dBm */
 
 #ifdef CONFIG_MAC80211_DEBUGFS
 	struct local_debugfsdentries {
@@ -985,6 +986,9 @@ void ieee80211_chswitch_work(struct work_struct *work);
 void ieee80211_process_chanswitch(struct ieee80211_sub_if_data *sdata,
 				  struct ieee80211_channel_sw_ie *sw_elem,
 				  struct ieee80211_bss *bss);
+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 e9f3e85..c78304d 100644
--- a/net/mac80211/main.c
+++ b/net/mac80211/main.c
@@ -214,10 +214,16 @@ int ieee80211_hw_config(struct ieee80211_local *local, u32 changed)
 		changed |= IEEE80211_CONF_CHANGE_CHANNEL;
 	}
 
-	if (!local->user_power_level)
+	if (local->sw_scanning)
 		power = chan->max_power;
 	else
-		power = min(chan->max_power, local->user_power_level);
+		power = local->power_constr_level ?
+			(chan->max_power - local->power_constr_level) :
+			chan->max_power;
+
+	if (local->user_power_level)
+		power = min(power, local->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 82c598a..f0d4249 100644
--- a/net/mac80211/mlme.c
+++ b/net/mac80211/mlme.c
@@ -905,6 +905,8 @@ static void ieee80211_set_disassoc(struct ieee80211_sub_if_data *sdata,
 	/* channel(_type) changes are handled by ieee80211_hw_config */
 	local->oper_channel_type = NL80211_CHAN_NO_HT;
 
+	local->power_constr_level = 0;
+
 	del_timer_sync(&local->dynamic_ps_timer);
 	cancel_work_sync(&local->dynamic_ps_enable_work);
 
@@ -1849,6 +1851,13 @@ static void ieee80211_rx_mgmt_beacon(struct ieee80211_sub_if_data *sdata,
 		 * for the BSSID we are associated to */
 		regulatory_hint_11d(local->hw.wiphy,
 			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 8396b5a..8d4ec29 100644
--- a/net/mac80211/spectmgmt.c
+++ b/net/mac80211/spectmgmt.c
@@ -161,3 +161,24 @@ void ieee80211_process_chanswitch(struct ieee80211_sub_if_data *sdata,
 			  jiffies + msecs_to_jiffies(sw_elem->count * bss->beacon_int));
 	}
 }
+
+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 (!(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 != sdata->local->power_constr_level)) {
+		sdata->local->power_constr_level = *pwr_constr_elem;
+		ieee80211_hw_config(sdata->local, 0);
+	}
+}
+