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-rw-r--r--net/mac80211/mesh_sync.c296
1 files changed, 296 insertions, 0 deletions
diff --git a/net/mac80211/mesh_sync.c b/net/mac80211/mesh_sync.c
new file mode 100644
index 0000000..f78b013
--- /dev/null
+++ b/net/mac80211/mesh_sync.c
@@ -0,0 +1,296 @@
+/*
+ * 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"
+
+#ifdef CONFIG_MAC80211_VERBOSE_MESH_SYNC_DEBUG
+#define msync_dbg(fmt, args...) \
+ printk(KERN_DEBUG "Mesh sync (%s): " fmt "\n", sdata->name, ##args)
+#else
+#define msync_dbg(fmt, args...) do { (void)(0); } while (0)
+#endif
+
+/* This is not in the standard. It represents a tolerable tbtt drift below
+ * which we do no TSF adjustment.
+ */
+#define TBTT_MINIMUM_ADJUSTMENT 10
+
+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 &
+ 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("TBTT : max clockdrift=%lld; adjusting",
+ (long long) ifmsh->sync_offset_clockdrift_max);
+ tsfdelta = -ifmsh->sync_offset_clockdrift_max;
+ ifmsh->sync_offset_clockdrift_max = 0;
+ } else {
+ msync_dbg("TBTT : max clockdrift=%lld; adjusting by %llu",
+ (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;
+ }
+
+ tsf = drv_get_tsf(local, sdata);
+ if (tsf != -1ULL)
+ drv_set_tsf(local, sdata, tsf + tsfdelta);
+ spin_unlock_bh(&ifmsh->sync_offset_lock);
+}
+
+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;
+
+ /* The current tsf is a first approximation for the timestamp
+ * for the received beacon. Further down we try to get a
+ * better value from the rx_status->mactime field if
+ * available. Also we have to call drv_get_tsf() before
+ * entering the rcu-read section.*/
+ 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("STA %pM : is adjusting TBTT", sta->sta.addr);
+ goto no_sync;
+ }
+
+ if (rx_status->flag & RX_FLAG_MACTIME_MPDU && rx_status->mactime) {
+ /*
+ * The mactime is defined as the time the first data symbol
+ * of the frame hits the PHY, and the timestamp of the beacon
+ * is defined as "the time that the data symbol containing the
+ * first bit of the timestamp is transmitted to the PHY plus
+ * the transmitting STA's delays through its local PHY from the
+ * MAC-PHY interface to its interface with the WM" (802.11
+ * 11.1.2)
+ *
+ * T_r, in 13.13.2.2.2, is just defined as "the frame reception
+ * time" but we unless we interpret that time to be the same
+ * time of the beacon timestamp, the offset calculation will be
+ * off. Below we adjust t_r to be "the time at which the first
+ * symbol of the timestamp element in the beacon is received".
+ * This correction depends on the rate.
+ *
+ * Based on similar code in ibss.c
+ */
+ int rate;
+
+ if (rx_status->flag & RX_FLAG_HT) {
+ /* TODO:
+ * In principle there could be HT-beacons (Dual Beacon
+ * HT Operation options), but for now ignore them and
+ * just use the primary (i.e. non-HT) beacons for
+ * synchronization.
+ * */
+ goto no_sync;
+ } else
+ rate = local->hw.wiphy->bands[rx_status->band]->
+ bitrates[rx_status->rate_idx].bitrate;
+
+ /* 24 bytes of header * 8 bits/byte *
+ * 10*(100 Kbps)/Mbps / rate (100 Kbps)*/
+ t_r = rx_status->mactime + (24 * 8 * 10 / rate);
+ }
+
+ /* 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("STA %pM : sta->t_offset=%lld,"
+ " sta->t_offset_setpoint=%lld,"
+ " t_clockdrift=%lld",
+ sta->sta.addr,
+ (long long) sta->t_offset,
+ (long long)
+ sta->t_offset_setpoint,
+ (long long) t_clockdrift);
+ rcu_read_unlock();
+
+ 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;
+ set_sta_flag(sta, WLAN_STA_TOFFSET_KNOWN);
+ msync_dbg("STA %pM : offset was invalid, "
+ " sta->t_offset=%lld",
+ sta->sta.addr,
+ (long long) sta->t_offset);
+ rcu_read_unlock();
+ }
+ return;
+
+no_sync:
+ rcu_read_unlock();
+}
+
+static void mesh_sync_offset_adjust_tbtt(struct ieee80211_sub_if_data *sdata)
+{
+ struct ieee80211_if_mesh *ifmsh = &sdata->u.mesh;
+
+ WARN_ON(ifmsh->mesh_sp_id
+ != IEEE80211_SYNC_METHOD_NEIGHBOR_OFFSET);
+ BUG_ON(!rcu_read_lock_held());
+
+ spin_lock_bh(&ifmsh->sync_offset_lock);
+
+ if (ifmsh->sync_offset_clockdrift_max >
+ TBTT_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("TBTT : kicking off TBTT "
+ "adjustment with "
+ "clockdrift_max=%lld",
+ ifmsh->sync_offset_clockdrift_max);
+ set_bit(MESH_WORK_DRIFT_ADJUST,
+ &ifmsh->wrkq_flags);
+ } else {
+ msync_dbg("TBTT : max clockdrift=%lld; "
+ "too small to adjust",
+ (long long)
+ ifmsh->sync_offset_clockdrift_max);
+ ifmsh->sync_offset_clockdrift_max = 0;
+ }
+ spin_unlock_bh(&ifmsh->sync_offset_lock);
+}
+
+static const u8 *mesh_get_vendor_oui(struct ieee80211_sub_if_data *sdata)
+{
+ struct ieee80211_if_mesh *ifmsh = &sdata->u.mesh;
+ u8 offset;
+
+ if (!ifmsh->ie || !ifmsh->ie_len)
+ return NULL;
+
+ offset = ieee80211_ie_split_vendor(ifmsh->ie,
+ ifmsh->ie_len, 0);
+
+ if (!offset)
+ return NULL;
+
+ return ifmsh->ie + offset + 2;
+}
+
+static void mesh_sync_vendor_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)
+{
+ const u8 *oui;
+
+ WARN_ON(sdata->u.mesh.mesh_sp_id != IEEE80211_SYNC_METHOD_VENDOR);
+ msync_dbg("called mesh_sync_vendor_rx_bcn_presp");
+ oui = mesh_get_vendor_oui(sdata);
+ /* here you would implement the vendor offset tracking for this oui */
+}
+
+static void mesh_sync_vendor_adjust_tbtt(struct ieee80211_sub_if_data *sdata)
+{
+ const u8 *oui;
+
+ WARN_ON(sdata->u.mesh.mesh_sp_id != IEEE80211_SYNC_METHOD_VENDOR);
+ msync_dbg("called mesh_sync_vendor_adjust_tbtt");
+ oui = mesh_get_vendor_oui(sdata);
+ /* here you would implement the vendor tsf adjustment for this oui */
+}
+
+/* global variable */
+static 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,
+ }
+ },
+ {
+ .method = IEEE80211_SYNC_METHOD_VENDOR,
+ .ops = {
+ .rx_bcn_presp = &mesh_sync_vendor_rx_bcn_presp,
+ .adjust_tbtt = &mesh_sync_vendor_adjust_tbtt,
+ }
+ },
+};
+
+struct ieee80211_mesh_sync_ops *ieee80211_mesh_sync_ops_get(u8 method)
+{
+ struct ieee80211_mesh_sync_ops *ops = NULL;
+ u8 i;
+
+ for (i = 0 ; i < ARRAY_SIZE(sync_methods); ++i) {
+ if (sync_methods[i].method == method) {
+ ops = &sync_methods[i].ops;
+ break;
+ }
+ }
+ return ops;
+}
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