diff options
Diffstat (limited to 'net/mac80211/mesh_sync.c')
| -rw-r--r-- | net/mac80211/mesh_sync.c | 213 |
1 files changed, 213 insertions, 0 deletions
diff --git a/net/mac80211/mesh_sync.c b/net/mac80211/mesh_sync.c new file mode 100644 index 000000000..9e342cc25 --- /dev/null +++ b/net/mac80211/mesh_sync.c @@ -0,0 +1,213 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * 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. + * Copyright (C) 2021 Intel Corporation + */ + +#include "ieee80211_i.h" +#include "mesh.h" +#include "driver-ops.h" + +/* This is not in the standard. It represents a tolerable tsf 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 800 /* 0.8 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 + * + * @cfg: mesh config element from the mesh peer (or %NULL) + */ +static bool mesh_peer_tbtt_adjusting(const struct ieee80211_meshconf_ie *cfg) +{ + return cfg && + (cfg->meshconf_cap & IEEE80211_MESHCONF_CAPAB_TBTT_ADJUSTING); +} + +void mesh_sync_adjust_tsf(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, "TSF : 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, "TSF : 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); + + if (local->ops->offset_tsf) { + drv_offset_tsf(local, sdata, tsfdelta); + } else { + 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, unsigned int len, + const struct ieee80211_meshconf_ie *mesh_cfg, + 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, + 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 (mesh_peer_tbtt_adjusting(mesh_cfg)) { + 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->mesh->t_offset = t_t - t_r; + + if (test_sta_flag(sta, WLAN_STA_TOFFSET_KNOWN)) { + s64 t_clockdrift = sta->mesh->t_offset_setpoint - sta->mesh->t_offset; + msync_dbg(sdata, + "STA %pM : t_offset=%lld, t_offset_setpoint=%lld, t_clockdrift=%lld\n", + sta->sta.addr, (long long) sta->mesh->t_offset, + (long long) sta->mesh->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->mesh->t_offset_setpoint = sta->mesh->t_offset - TOFFSET_SET_MARGIN; + set_sta_flag(sta, WLAN_STA_TOFFSET_KNOWN); + msync_dbg(sdata, + "STA %pM : offset was invalid, t_offset=%lld\n", + sta->sta.addr, + (long long) sta->mesh->t_offset); + } + +no_sync: + rcu_read_unlock(); +} + +static void mesh_sync_offset_adjust_tsf(struct ieee80211_sub_if_data *sdata, + struct beacon_data *beacon) +{ + struct ieee80211_if_mesh *ifmsh = &sdata->u.mesh; + + WARN_ON(ifmsh->mesh_sp_id != IEEE80211_SYNC_METHOD_NEIGHBOR_OFFSET); + WARN_ON(!rcu_read_lock_held()); + + 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, + "TSF : kicking off TSF adjustment with clockdrift_max=%lld\n", + ifmsh->sync_offset_clockdrift_max); + set_bit(MESH_WORK_DRIFT_ADJUST, &ifmsh->wrkq_flags); + } else { + msync_dbg(sdata, + "TSF : max clockdrift=%lld; too small to adjust\n", + (long long)ifmsh->sync_offset_clockdrift_max); + ifmsh->sync_offset_clockdrift_max = 0; + } + spin_unlock_bh(&ifmsh->sync_offset_lock); +} + +static const struct sync_method sync_methods[] = { + { + .method = IEEE80211_SYNC_METHOD_NEIGHBOR_OFFSET, + .ops = { + .rx_bcn_presp = &mesh_sync_offset_rx_bcn_presp, + .adjust_tsf = &mesh_sync_offset_adjust_tsf, + } + }, +}; + +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; +} |