mac80211: allow releasing driver-buffered frames

If there are frames for a station buffered in
the driver, mac80211 announces those in the TIM
IE but there's no way to release them. Add new
API to release such frames and use it when the
station polls for a frame.

Since the API will soon also be used for uAPSD
it is easily extensible.

Note that before this change drivers announcing
driver-buffered frames in the TIM bit actually
will respond to a PS-Poll with a potentially
lower priority frame (if there are any frames
buffered in mac80211), after this patch a driver
that hasn't been changed will no longer respond
at all. This only affects ath9k, which will need
to be fixed to implement the new API.

Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

1 files changed, 31 insertions, 0 deletions

diff --git a/include/net/mac80211.h b/include/net/mac80211.h
index acf9eaf..dc2ea46 100644
--- a/include/net/mac80211.h
+++ b/include/net/mac80211.h
@@ -1622,6 +1622,14 @@ enum ieee80211_tx_sync_type {
 };
 
 /**
+ * enum ieee80211_frame_release_type - frame release reason
+ * @IEEE80211_FRAME_RELEASE_PSPOLL: frame released for PS-Poll
+ */
+enum ieee80211_frame_release_type {
+	IEEE80211_FRAME_RELEASE_PSPOLL,
+};
+
+/**
  * struct ieee80211_ops - callbacks from mac80211 to the driver
  *
  * This structure contains various callbacks that the driver may
@@ -1931,6 +1939,23 @@ enum ieee80211_tx_sync_type {
  *	The callback can sleep.
  * @rssi_callback: Notify driver when the average RSSI goes above/below
  *	thresholds that were registered previously. The callback can sleep.
+ *
+ * @release_buffered_frames: Release buffered frames according to the given
+ *	parameters. In the case where the driver buffers some frames for
+ *	sleeping stations mac80211 will use this callback to tell the driver
+ *	to release some frames, either for PS-poll or uAPSD.
+ *	Note that if the @more_data paramter is %false the driver must check
+ *	if there are more frames on the given TIDs, and if there are more than
+ *	the frames being released then it must still set the more-data bit in
+ *	the frame. If the @more_data parameter is %true, then of course the
+ *	more-data bit must always be set.
+ *	The @tids parameter tells the driver which TIDs to release frames
+ *	from, for PS-poll it will always have only a single bit set.
+ *	In the case this is used for uAPSD, the @num_frames parameter may be
+ *	bigger than one, but the driver may send fewer frames (it must send
+ *	at least one, however). In this case it is also responsible for
+ *	setting the EOSP flag in the QoS header of the frames.
+ *	This callback must be atomic.
  */
 struct ieee80211_ops {
 	void (*tx)(struct ieee80211_hw *hw, struct sk_buff *skb);
@@ -2045,6 +2070,12 @@ struct ieee80211_ops {
 				const struct cfg80211_bitrate_mask *mask);
 	void (*rssi_callback)(struct ieee80211_hw *hw,
 			      enum ieee80211_rssi_event rssi_event);
+
+	void (*release_buffered_frames)(struct ieee80211_hw *hw,
+					struct ieee80211_sta *sta,
+					u16 tids, int num_frames,
+					enum ieee80211_frame_release_type reason,
+					bool more_data);
 };
 
 /**