mac80211: sync dtim_count to TSF

On starting a mesh or AP BSS, the interface dtim_count
countdown should match that of the driver TSF.

Signed-off-by: Thomas Pedersen <twpedersen@gmail.com>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

1 files changed, 41 insertions, 0 deletions

diff --git a/net/mac80211/util.c b/net/mac80211/util.c
index df00f1978a77..676dc0967f37 100644
--- a/net/mac80211/util.c
+++ b/net/mac80211/util.c
@@ -2734,3 +2734,44 @@ int ieee80211_parse_p2p_noa(const struct ieee80211_p2p_noa_attr *attr,
         return ret;
 }
 EXPORT_SYMBOL(ieee80211_parse_p2p_noa);
+
+void ieee80211_recalc_dtim(struct ieee80211_local *local,
+                           struct ieee80211_sub_if_data *sdata)
+{
+        u64 tsf = drv_get_tsf(local, sdata);
+        u64 dtim_count = 0;
+        u16 beacon_int = sdata->vif.bss_conf.beacon_int * 1024;
+        u8 dtim_period = sdata->vif.bss_conf.dtim_period;
+        struct ps_data *ps;
+        u8 bcns_from_dtim;
+
+        if (tsf == -1ULL || !beacon_int || !dtim_period)
+                return;
+
+        if (sdata->vif.type == NL80211_IFTYPE_AP ||
+            sdata->vif.type == NL80211_IFTYPE_AP_VLAN) {
+                if (!sdata->bss)
+                        return;
+
+                ps = &sdata->bss->ps;
+        } else if (ieee80211_vif_is_mesh(&sdata->vif)) {
+                ps = &sdata->u.mesh.ps;
+        } else {
+                return;
+        }
+
+        /*
+         * actually finds last dtim_count, mac80211 will update in
+         * __beacon_add_tim().
+         * dtim_count = dtim_period - (tsf / bcn_int) % dtim_period
+         */
+        do_div(tsf, beacon_int);
+        bcns_from_dtim = do_div(tsf, dtim_period);
+        /* just had a DTIM */
+        if (!bcns_from_dtim)
+                dtim_count = 0;
+        else
+                dtim_count = dtim_period - bcns_from_dtim;
+
+        ps->dtim_count = dtim_count;
+}