mac80211: add U-APSD client support

Add Unscheduled Automatic Power-Save Delivery (U-APSD) client support. The
idea is that the data frames from the client trigger AP to send the buffered
frames with ACs which have U-APSD enabled. This decreases latency and makes it
possible to save even more power.

Driver needs to use IEEE80211_HW_UAPSD to enable the feature. The current
implementation assumes that firmware takes care of the wakeup and
hardware needing IEEE80211_HW_PS_NULLFUNC_STACK is not yet supported.

Tested with wl1251 on a Nokia N900 and Cisco Aironet 1231G AP and running
various test traffic with ping.

Signed-off-by: Kalle Valo <kalle.valo@nokia.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

1 files changed, 18 insertions, 0 deletions

diff --git a/net/mac80211/scan.c b/net/mac80211/scan.c
index 30cb62bb45b3..9afe2f9885dc 100644
--- a/net/mac80211/scan.c
+++ b/net/mac80211/scan.c
@@ -54,6 +54,23 @@ void ieee80211_rx_bss_put(struct ieee80211_local *local,
         cfg80211_put_bss(container_of((void *)bss, struct cfg80211_bss, priv));
 }
 
+static bool is_uapsd_supported(struct ieee802_11_elems *elems)
+{
+        u8 qos_info;
+
+        if (elems->wmm_info && elems->wmm_info_len == 7
+            && elems->wmm_info[5] == 1)
+                qos_info = elems->wmm_info[6];
+        else if (elems->wmm_param && elems->wmm_param_len == 24
+                 && elems->wmm_param[5] == 1)
+                qos_info = elems->wmm_param[6];
+        else
+                /* no valid wmm information or parameter element found */
+                return false;
+
+        return qos_info & IEEE80211_WMM_IE_AP_QOSINFO_UAPSD;
+}
+
 struct ieee80211_bss *
 ieee80211_bss_info_update(struct ieee80211_local *local,
                           struct ieee80211_rx_status *rx_status,
@@ -117,6 +134,7 @@ ieee80211_bss_info_update(struct ieee80211_local *local,
         }
 
         bss->wmm_used = elems->wmm_param || elems->wmm_info;
+        bss->uapsd_supported = is_uapsd_supported(elems);
 
         if (!beacon)
                 bss->last_probe_resp = jiffies;