--- /dev/null
+/*
+ * Copyright 2011-2012, Pavel Zubarev <pavel.zubarev@gmail.com>
+ * Copyright 2011-2012, Marco Porsch <marco.porsch@s2005.tu-chemnitz.de>
+ * Copyright 2011-2012, cozybit Inc.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+
+#include "ieee80211_i.h"
+#include "mesh.h"
+#include "driver-ops.h"
+
+/* This is not in the standard. It represents a tolerable tbtt drift below
+ * which we do no TSF adjustment.
+ */
+#define TOFFSET_MINIMUM_ADJUSTMENT 10
+
+/* This is not in the standard. It is a margin added to the
+ * Toffset setpoint to mitigate TSF overcorrection
+ * introduced by TSF adjustment latency.
+ */
+#define TOFFSET_SET_MARGIN 20
+
+/* This is not in the standard. It represents the maximum Toffset jump above
+ * which we'll invalidate the Toffset setpoint and choose a new setpoint. This
+ * could be, for instance, in case a neighbor is restarted and its TSF counter
+ * reset.
+ */
+#define TOFFSET_MAXIMUM_ADJUSTMENT 30000 /* 30 ms */
+
+struct sync_method {
+ u8 method;
+ struct ieee80211_mesh_sync_ops ops;
+};
+
+/**
+ * mesh_peer_tbtt_adjusting - check if an mp is currently adjusting its TBTT
+ *
+ * @ie: information elements of a management frame from the mesh peer
+ */
+static bool mesh_peer_tbtt_adjusting(struct ieee802_11_elems *ie)
+{
+ return (ie->mesh_config->meshconf_cap &
+ IEEE80211_MESHCONF_CAPAB_TBTT_ADJUSTING) != 0;
+}
+
+void mesh_sync_adjust_tbtt(struct ieee80211_sub_if_data *sdata)
+{
+ struct ieee80211_local *local = sdata->local;
+ struct ieee80211_if_mesh *ifmsh = &sdata->u.mesh;
+ /* sdata->vif.bss_conf.beacon_int in 1024us units, 0.04% */
+ u64 beacon_int_fraction = sdata->vif.bss_conf.beacon_int * 1024 / 2500;
+ u64 tsf;
+ u64 tsfdelta;
+
+ spin_lock_bh(&ifmsh->sync_offset_lock);
+ if (ifmsh->sync_offset_clockdrift_max < beacon_int_fraction) {
+ msync_dbg(sdata, "TBTT : max clockdrift=%lld; adjusting\n",
+ (long long) ifmsh->sync_offset_clockdrift_max);
+ tsfdelta = -ifmsh->sync_offset_clockdrift_max;
+ ifmsh->sync_offset_clockdrift_max = 0;
+ } else {
+ msync_dbg(sdata, "TBTT : max clockdrift=%lld; adjusting by %llu\n",
+ (long long) ifmsh->sync_offset_clockdrift_max,
+ (unsigned long long) beacon_int_fraction);
+ tsfdelta = -beacon_int_fraction;
+ ifmsh->sync_offset_clockdrift_max -= beacon_int_fraction;
+ }
+ spin_unlock_bh(&ifmsh->sync_offset_lock);
+
+ tsf = drv_get_tsf(local, sdata);
+ if (tsf != -1ULL)
+ drv_set_tsf(local, sdata, tsf + tsfdelta);
+}
+
+static void mesh_sync_offset_rx_bcn_presp(struct ieee80211_sub_if_data *sdata,
+ u16 stype,
+ struct ieee80211_mgmt *mgmt,
+ struct ieee802_11_elems *elems,
+ struct ieee80211_rx_status *rx_status)
+{
+ struct ieee80211_if_mesh *ifmsh = &sdata->u.mesh;
+ struct ieee80211_local *local = sdata->local;
+ struct sta_info *sta;
+ u64 t_t, t_r;
+
+ WARN_ON(ifmsh->mesh_sp_id != IEEE80211_SYNC_METHOD_NEIGHBOR_OFFSET);
+
+ /* standard mentions only beacons */
+ if (stype != IEEE80211_STYPE_BEACON)
+ return;
+
+ /*
+ * Get time when timestamp field was received. If we don't
+ * have rx timestamps, then use current tsf as an approximation.
+ * drv_get_tsf() must be called before entering the rcu-read
+ * section.
+ */
+ if (ieee80211_have_rx_timestamp(rx_status))
+ t_r = ieee80211_calculate_rx_timestamp(local, rx_status,
+ 24 + 12 +
+ elems->total_len +
+ FCS_LEN,
+ 24);
+ else
+ t_r = drv_get_tsf(local, sdata);
+
+ rcu_read_lock();
+ sta = sta_info_get(sdata, mgmt->sa);
+ if (!sta)
+ goto no_sync;
+
+ /* check offset sync conditions (13.13.2.2.1)
+ *
+ * TODO also sync to
+ * dot11MeshNbrOffsetMaxNeighbor non-peer non-MBSS neighbors
+ */
+
+ if (elems->mesh_config && mesh_peer_tbtt_adjusting(elems)) {
+ clear_sta_flag(sta, WLAN_STA_TOFFSET_KNOWN);
+ msync_dbg(sdata, "STA %pM : is adjusting TBTT\n",
+ sta->sta.addr);
+ goto no_sync;
+ }
+
+ /* Timing offset calculation (see 13.13.2.2.2) */
+ t_t = le64_to_cpu(mgmt->u.beacon.timestamp);
+ sta->t_offset = t_t - t_r;
+
+ if (test_sta_flag(sta, WLAN_STA_TOFFSET_KNOWN)) {
+ s64 t_clockdrift = sta->t_offset_setpoint - sta->t_offset;
+ msync_dbg(sdata,
+ "STA %pM : sta->t_offset=%lld, sta->t_offset_setpoint=%lld, t_clockdrift=%lld\n",
+ sta->sta.addr, (long long) sta->t_offset,
+ (long long) sta->t_offset_setpoint,
+ (long long) t_clockdrift);
+
+ if (t_clockdrift > TOFFSET_MAXIMUM_ADJUSTMENT ||
+ t_clockdrift < -TOFFSET_MAXIMUM_ADJUSTMENT) {
+ msync_dbg(sdata,
+ "STA %pM : t_clockdrift=%lld too large, setpoint reset\n",
+ sta->sta.addr,
+ (long long) t_clockdrift);
+ clear_sta_flag(sta, WLAN_STA_TOFFSET_KNOWN);
+ goto no_sync;
+ }
+
+ spin_lock_bh(&ifmsh->sync_offset_lock);
+ if (t_clockdrift > ifmsh->sync_offset_clockdrift_max)
+ ifmsh->sync_offset_clockdrift_max = t_clockdrift;
+ spin_unlock_bh(&ifmsh->sync_offset_lock);
+ } else {
+ sta->t_offset_setpoint = sta->t_offset - TOFFSET_SET_MARGIN;
+ set_sta_flag(sta, WLAN_STA_TOFFSET_KNOWN);
+ msync_dbg(sdata,
+ "STA %pM : offset was invalid, sta->t_offset=%lld\n",
+ sta->sta.addr,
+ (long long) sta->t_offset);
+ }
+
+no_sync:
+ rcu_read_unlock();
+}
+
+static void mesh_sync_offset_adjust_tbtt(struct ieee80211_sub_if_data *sdata,
+ struct beacon_data *beacon)
+{
+ struct ieee80211_if_mesh *ifmsh = &sdata->u.mesh;
+ u8 cap;
+
+ WARN_ON(ifmsh->mesh_sp_id != IEEE80211_SYNC_METHOD_NEIGHBOR_OFFSET);
+ WARN_ON(!rcu_read_lock_held());
+ cap = beacon->meshconf->meshconf_cap;
+
+ spin_lock_bh(&ifmsh->sync_offset_lock);
+
+ if (ifmsh->sync_offset_clockdrift_max > TOFFSET_MINIMUM_ADJUSTMENT) {
+ /* Since ajusting the tsf here would
+ * require a possibly blocking call
+ * to the driver tsf setter, we punt
+ * the tsf adjustment to the mesh tasklet
+ */
+ msync_dbg(sdata,
+ "TBTT : kicking off TBTT adjustment with clockdrift_max=%lld\n",
+ ifmsh->sync_offset_clockdrift_max);
+ set_bit(MESH_WORK_DRIFT_ADJUST, &ifmsh->wrkq_flags);
+
+ ifmsh->adjusting_tbtt = true;
+ } else {
+ msync_dbg(sdata,
+ "TBTT : max clockdrift=%lld; too small to adjust\n",
+ (long long)ifmsh->sync_offset_clockdrift_max);
+ ifmsh->sync_offset_clockdrift_max = 0;
+
+ ifmsh->adjusting_tbtt = false;
+ }
+ spin_unlock_bh(&ifmsh->sync_offset_lock);
+
+ beacon->meshconf->meshconf_cap = ifmsh->adjusting_tbtt ?
+ IEEE80211_MESHCONF_CAPAB_TBTT_ADJUSTING | cap :
+ ~IEEE80211_MESHCONF_CAPAB_TBTT_ADJUSTING & cap;
+}
+
+static const struct sync_method sync_methods[] = {
+ {
+ .method = IEEE80211_SYNC_METHOD_NEIGHBOR_OFFSET,
+ .ops = {
+ .rx_bcn_presp = &mesh_sync_offset_rx_bcn_presp,
+ .adjust_tbtt = &mesh_sync_offset_adjust_tbtt,
+ }
+ },
+};
+
+const struct ieee80211_mesh_sync_ops *ieee80211_mesh_sync_ops_get(u8 method)
+{
+ int i;
+
+ for (i = 0 ; i < ARRAY_SIZE(sync_methods); ++i) {
+ if (sync_methods[i].method == method)
+ return &sync_methods[i].ops;
+ }
+ return NULL;
+}
Code Review / kvmfornfv.git / blobdiff