mac80211: make listen_interval be limited by low level driver

This patch makes possible for a driver to specify maximal listen interval
The possibility for user to configure listen interval is not implemented
yet, currently the maximum provided by the driver or 1 is used.
Mac80211 uses config handler to set listen interval for to the driver.

Signed-off-by: Tomas Winkler <tomas.winkler@intel.com>
Signed-off-by: Emmanuel Grumbach <emmanuel.grumbach@intel.com>
Signed-off-by: Zhu Yi <yi.zhu@intel.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

include/net/mac80211.h

@@ -432,6 +432,7 @@ enum ieee80211_conf_flags {
  * @radio_enabled: when zero, driver is required to switch off the radio.
  *	TODO make a flag
  * @beacon_int: beacon interval (TODO make interface config)
+ * @listen_interval: listen interval in units of beacon interval
  * @flags: configuration flags defined above
  * @power_level: requested transmit power (in dBm)
  * @max_antenna_gain: maximum antenna gain (in dBi)
@@ -446,6 +447,7 @@ struct ieee80211_conf {
 	int radio_enabled;
 
 	int beacon_int;
+	u16 listen_interval;
 	u32 flags;
 	int power_level;
 	int max_antenna_gain;
@@ -787,6 +789,9 @@ enum ieee80211_hw_flags {
  * @max_signal: Maximum value for signal (rssi) in RX information, used
  *     only when @IEEE80211_HW_SIGNAL_UNSPEC or @IEEE80211_HW_SIGNAL_DB
  *
+ * @max_listen_interval: max listen interval in units of beacon interval
+ *     that HW supports
+ *
  * @queues: number of available hardware transmit queues for
  *	data packets. WMM/QoS requires at least four, these
  *	queues need to have configurable access parameters.
@@ -814,7 +819,9 @@ struct ieee80211_hw {
 	unsigned int extra_tx_headroom;
 	int channel_change_time;
 	int vif_data_size;
-	u16 queues, ampdu_queues;
+	u16 queues;
+	u16 ampdu_queues;
+	u16 max_listen_interval;
 	s8 max_signal;
 };