mac80211: add driver RSSI threshold events

mac80211 maintains a running average of the RSSI when a STA
is associated to an AP. Report threshold events to any driver
that has registered callbacks for getting RSSI measurements.

Implement callbacks in mac80211 so that driver can set thresholds.
Add callbacks in mac80211 which is invoked when an RSSI threshold
event occurs.

mac80211: add tracing to rssi_reports api and remove extraneous fn argument
mac80211: scale up rssi thresholds from driver by 16 before storing

Signed-off-by: Meenakshi Venkataraman <meenakshi.venkataraman@intel.com>
Signed-off-by: Wey-Yi Guy <wey-yi.w.guy@intel.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

5 files changed, 125 insertions, 0 deletions

diff --git a/net/mac80211/driver-ops.h b/net/mac80211/driver-ops.h
index edd2dd79c9be..b2d6bba44054 100644
--- a/net/mac80211/driver-ops.h
+++ b/net/mac80211/driver-ops.h
@@ -657,4 +657,12 @@ static inline void drv_set_rekey_data(struct ieee80211_local *local,
         trace_drv_return_void(local);
 }
 
+static inline void drv_rssi_callback(struct ieee80211_local *local,
+                                     const enum ieee80211_rssi_event event)
+{
+        trace_drv_rssi_callback(local, event);
+        if (local->ops->rssi_callback)
+                local->ops->rssi_callback(&local->hw, event);
+        trace_drv_return_void(local);
+}
 #endif /* __MAC80211_DRIVER_OPS */
diff --git a/net/mac80211/driver-trace.h b/net/mac80211/driver-trace.h
index 31a9dfa81f65..4470f6e8b845 100644
--- a/net/mac80211/driver-trace.h
+++ b/net/mac80211/driver-trace.h
@@ -1052,6 +1052,28 @@ TRACE_EVENT(drv_set_rekey_data,
                   LOCAL_PR_ARG, VIF_PR_ARG)
 );
 
+TRACE_EVENT(drv_rssi_callback,
+        TP_PROTO(struct ieee80211_local *local,
+                 enum ieee80211_rssi_event rssi_event),
+
+        TP_ARGS(local, rssi_event),
+
+        TP_STRUCT__entry(
+                LOCAL_ENTRY
+                __field(u32, rssi_event)
+        ),
+
+        TP_fast_assign(
+                LOCAL_ASSIGN;
+                __entry->rssi_event = rssi_event;
+        ),
+
+        TP_printk(
+                LOCAL_PR_FMT " rssi_event:%d",
+                LOCAL_PR_ARG, __entry->rssi_event
+        )
+);
+
 /*
  * Tracing for API calls that drivers call.
  */
@@ -1342,6 +1364,30 @@ TRACE_EVENT(api_gtk_rekey_notify,
         TP_printk(VIF_PR_FMT, VIF_PR_ARG)
 );
 
+TRACE_EVENT(api_enable_rssi_reports,
+        TP_PROTO(struct ieee80211_sub_if_data *sdata,
+                 int rssi_min_thold, int rssi_max_thold),
+
+        TP_ARGS(sdata, rssi_min_thold, rssi_max_thold),
+
+        TP_STRUCT__entry(
+                VIF_ENTRY
+                __field(int, rssi_min_thold)
+                __field(int, rssi_max_thold)
+        ),
+
+        TP_fast_assign(
+                VIF_ASSIGN;
+                __entry->rssi_min_thold = rssi_min_thold;
+                __entry->rssi_max_thold = rssi_max_thold;
+        ),
+
+        TP_printk(
+                VIF_PR_FMT " rssi_min_thold =%d, rssi_max_thold = %d",
+                VIF_PR_ARG, __entry->rssi_min_thold, __entry->rssi_max_thold
+        )
+);
+
 /*
  * Tracing for internal functions
  * (which may also be called in response to driver calls)
diff --git a/net/mac80211/ieee80211_i.h b/net/mac80211/ieee80211_i.h
index 4c7a831e7d1e..96600bec44c5 100644
--- a/net/mac80211/ieee80211_i.h
+++ b/net/mac80211/ieee80211_i.h
@@ -432,6 +432,14 @@ struct ieee80211_if_managed {
          * generated for the current association.
          */
         int last_cqm_event_signal;
+
+        /*
+         * State variables for keeping track of RSSI of the AP currently
+         * connected to and informing driver when RSSI has gone
+         * below/above a certain threshold.
+         */
+        int rssi_min_thold, rssi_max_thold;
+        int last_ave_beacon_signal;
 };
 
 struct ieee80211_if_ibss {
diff --git a/net/mac80211/mlme.c b/net/mac80211/mlme.c
index b6d9bd5f4d3c..4b0460ad8c8f 100644
--- a/net/mac80211/mlme.c
+++ b/net/mac80211/mlme.c
@@ -1763,6 +1763,7 @@ static void ieee80211_rx_mgmt_beacon(struct ieee80211_sub_if_data *sdata,
                 ifmgd->ave_beacon_signal = rx_status->signal * 16;
                 ifmgd->last_cqm_event_signal = 0;
                 ifmgd->count_beacon_signal = 1;
+                ifmgd->last_ave_beacon_signal = 0;
         } else {
                 ifmgd->ave_beacon_signal =
                         (IEEE80211_SIGNAL_AVE_WEIGHT * rx_status->signal * 16 +
@@ -1770,6 +1771,28 @@ static void ieee80211_rx_mgmt_beacon(struct ieee80211_sub_if_data *sdata,
                          ifmgd->ave_beacon_signal) / 16;
                 ifmgd->count_beacon_signal++;
         }
+
+        if (ifmgd->rssi_min_thold != ifmgd->rssi_max_thold &&
+            ifmgd->count_beacon_signal >= IEEE80211_SIGNAL_AVE_MIN_COUNT) {
+                int sig = ifmgd->ave_beacon_signal;
+                int last_sig = ifmgd->last_ave_beacon_signal;
+
+                /*
+                 * if signal crosses either of the boundaries, invoke callback
+                 * with appropriate parameters
+                 */
+                if (sig > ifmgd->rssi_max_thold &&
+                    (last_sig <= ifmgd->rssi_min_thold || last_sig == 0)) {
+                        ifmgd->last_ave_beacon_signal = sig;
+                        drv_rssi_callback(local, RSSI_EVENT_HIGH);
+                } else if (sig < ifmgd->rssi_min_thold &&
+                           (last_sig >= ifmgd->rssi_max_thold ||
+                           last_sig == 0)) {
+                        ifmgd->last_ave_beacon_signal = sig;
+                        drv_rssi_callback(local, RSSI_EVENT_LOW);
+                }
+        }
+
         if (bss_conf->cqm_rssi_thold &&
             ifmgd->count_beacon_signal >= IEEE80211_SIGNAL_AVE_MIN_COUNT &&
             !(local->hw.flags & IEEE80211_HW_SUPPORTS_CQM_RSSI)) {
diff --git a/net/mac80211/util.c b/net/mac80211/util.c
index 652e5695225a..190132063c99 100644
--- a/net/mac80211/util.c
+++ b/net/mac80211/util.c
@@ -1450,3 +1450,43 @@ size_t ieee80211_ie_split_vendor(const u8 *ies, size_t ielen, size_t offset)
 
         return pos;
 }
+
+static void _ieee80211_enable_rssi_reports(struct ieee80211_sub_if_data *sdata,
+                                            int rssi_min_thold,
+                                            int rssi_max_thold)
+{
+        trace_api_enable_rssi_reports(sdata, rssi_min_thold, rssi_max_thold);
+
+        if (WARN_ON(sdata->vif.type != NL80211_IFTYPE_STATION))
+                return;
+
+        /*
+         * Scale up threshold values before storing it, as the RSSI averaging
+         * algorithm uses a scaled up value as well. Change this scaling
+         * factor if the RSSI averaging algorithm changes.
+         */
+        sdata->u.mgd.rssi_min_thold = rssi_min_thold*16;
+        sdata->u.mgd.rssi_max_thold = rssi_max_thold*16;
+}
+
+void ieee80211_enable_rssi_reports(struct ieee80211_vif *vif,
+                                    int rssi_min_thold,
+                                    int rssi_max_thold)
+{
+        struct ieee80211_sub_if_data *sdata = vif_to_sdata(vif);
+
+        WARN_ON(rssi_min_thold == rssi_max_thold ||
+                rssi_min_thold > rssi_max_thold);
+
+        _ieee80211_enable_rssi_reports(sdata, rssi_min_thold,
+                                       rssi_max_thold);
+}
+EXPORT_SYMBOL(ieee80211_enable_rssi_reports);
+
+void ieee80211_disable_rssi_reports(struct ieee80211_vif *vif)
+{
+        struct ieee80211_sub_if_data *sdata = vif_to_sdata(vif);
+
+        _ieee80211_enable_rssi_reports(sdata, 0, 0);
+}
+EXPORT_SYMBOL(ieee80211_disable_rssi_reports);