1 // SPDX-License-Identifier: GPL-2.0-only 2 /* 3 * Copyright 2011-2012, Pavel Zubarev <pavel.zubarev@gmail.com> 4 * Copyright 2011-2012, Marco Porsch <marco.porsch@s2005.tu-chemnitz.de> 5 * Copyright 2011-2012, cozybit Inc. 6 * Copyright (C) 2021 Intel Corporation 7 */ 8 9 #include "ieee80211_i.h" 10 #include "mesh.h" 11 #include "driver-ops.h" 12 13 /* This is not in the standard. It represents a tolerable tsf drift below 14 * which we do no TSF adjustment. 15 */ 16 #define TOFFSET_MINIMUM_ADJUSTMENT 10 17 18 /* This is not in the standard. It is a margin added to the 19 * Toffset setpoint to mitigate TSF overcorrection 20 * introduced by TSF adjustment latency. 21 */ 22 #define TOFFSET_SET_MARGIN 20 23 24 /* This is not in the standard. It represents the maximum Toffset jump above 25 * which we'll invalidate the Toffset setpoint and choose a new setpoint. This 26 * could be, for instance, in case a neighbor is restarted and its TSF counter 27 * reset. 28 */ 29 #define TOFFSET_MAXIMUM_ADJUSTMENT 800 /* 0.8 ms */ 30 31 struct sync_method { 32 u8 method; 33 struct ieee80211_mesh_sync_ops ops; 34 }; 35 36 /** 37 * mesh_peer_tbtt_adjusting - check if an mp is currently adjusting its TBTT 38 * 39 * @cfg: mesh config element from the mesh peer (or %NULL) 40 */ 41 static bool mesh_peer_tbtt_adjusting(const struct ieee80211_meshconf_ie *cfg) 42 { 43 return cfg && 44 (cfg->meshconf_cap & IEEE80211_MESHCONF_CAPAB_TBTT_ADJUSTING); 45 } 46 47 void mesh_sync_adjust_tsf(struct ieee80211_sub_if_data *sdata) 48 { 49 struct ieee80211_local *local = sdata->local; 50 struct ieee80211_if_mesh *ifmsh = &sdata->u.mesh; 51 /* sdata->vif.bss_conf.beacon_int in 1024us units, 0.04% */ 52 u64 beacon_int_fraction = sdata->vif.bss_conf.beacon_int * 1024 / 2500; 53 u64 tsf; 54 u64 tsfdelta; 55 56 spin_lock_bh(&ifmsh->sync_offset_lock); 57 if (ifmsh->sync_offset_clockdrift_max < beacon_int_fraction) { 58 msync_dbg(sdata, "TSF : max clockdrift=%lld; adjusting\n", 59 (long long) ifmsh->sync_offset_clockdrift_max); 60 tsfdelta = -ifmsh->sync_offset_clockdrift_max; 61 ifmsh->sync_offset_clockdrift_max = 0; 62 } else { 63 msync_dbg(sdata, "TSF : max clockdrift=%lld; adjusting by %llu\n", 64 (long long) ifmsh->sync_offset_clockdrift_max, 65 (unsigned long long) beacon_int_fraction); 66 tsfdelta = -beacon_int_fraction; 67 ifmsh->sync_offset_clockdrift_max -= beacon_int_fraction; 68 } 69 spin_unlock_bh(&ifmsh->sync_offset_lock); 70 71 if (local->ops->offset_tsf) { 72 drv_offset_tsf(local, sdata, tsfdelta); 73 } else { 74 tsf = drv_get_tsf(local, sdata); 75 if (tsf != -1ULL) 76 drv_set_tsf(local, sdata, tsf + tsfdelta); 77 } 78 } 79 80 static void 81 mesh_sync_offset_rx_bcn_presp(struct ieee80211_sub_if_data *sdata, u16 stype, 82 struct ieee80211_mgmt *mgmt, unsigned int len, 83 const struct ieee80211_meshconf_ie *mesh_cfg, 84 struct ieee80211_rx_status *rx_status) 85 { 86 struct ieee80211_if_mesh *ifmsh = &sdata->u.mesh; 87 struct ieee80211_local *local = sdata->local; 88 struct sta_info *sta; 89 u64 t_t, t_r; 90 91 WARN_ON(ifmsh->mesh_sp_id != IEEE80211_SYNC_METHOD_NEIGHBOR_OFFSET); 92 93 /* standard mentions only beacons */ 94 if (stype != IEEE80211_STYPE_BEACON) 95 return; 96 97 /* 98 * Get time when timestamp field was received. If we don't 99 * have rx timestamps, then use current tsf as an approximation. 100 * drv_get_tsf() must be called before entering the rcu-read 101 * section. 102 */ 103 if (ieee80211_have_rx_timestamp(rx_status)) 104 t_r = ieee80211_calculate_rx_timestamp(local, rx_status, 105 len + FCS_LEN, 24); 106 else 107 t_r = drv_get_tsf(local, sdata); 108 109 rcu_read_lock(); 110 sta = sta_info_get(sdata, mgmt->sa); 111 if (!sta) 112 goto no_sync; 113 114 /* check offset sync conditions (13.13.2.2.1) 115 * 116 * TODO also sync to 117 * dot11MeshNbrOffsetMaxNeighbor non-peer non-MBSS neighbors 118 */ 119 120 if (mesh_peer_tbtt_adjusting(mesh_cfg)) { 121 msync_dbg(sdata, "STA %pM : is adjusting TBTT\n", 122 sta->sta.addr); 123 goto no_sync; 124 } 125 126 /* Timing offset calculation (see 13.13.2.2.2) */ 127 t_t = le64_to_cpu(mgmt->u.beacon.timestamp); 128 sta->mesh->t_offset = t_t - t_r; 129 130 if (test_sta_flag(sta, WLAN_STA_TOFFSET_KNOWN)) { 131 s64 t_clockdrift = sta->mesh->t_offset_setpoint - sta->mesh->t_offset; 132 msync_dbg(sdata, 133 "STA %pM : t_offset=%lld, t_offset_setpoint=%lld, t_clockdrift=%lld\n", 134 sta->sta.addr, (long long) sta->mesh->t_offset, 135 (long long) sta->mesh->t_offset_setpoint, 136 (long long) t_clockdrift); 137 138 if (t_clockdrift > TOFFSET_MAXIMUM_ADJUSTMENT || 139 t_clockdrift < -TOFFSET_MAXIMUM_ADJUSTMENT) { 140 msync_dbg(sdata, 141 "STA %pM : t_clockdrift=%lld too large, setpoint reset\n", 142 sta->sta.addr, 143 (long long) t_clockdrift); 144 clear_sta_flag(sta, WLAN_STA_TOFFSET_KNOWN); 145 goto no_sync; 146 } 147 148 spin_lock_bh(&ifmsh->sync_offset_lock); 149 if (t_clockdrift > ifmsh->sync_offset_clockdrift_max) 150 ifmsh->sync_offset_clockdrift_max = t_clockdrift; 151 spin_unlock_bh(&ifmsh->sync_offset_lock); 152 } else { 153 sta->mesh->t_offset_setpoint = sta->mesh->t_offset - TOFFSET_SET_MARGIN; 154 set_sta_flag(sta, WLAN_STA_TOFFSET_KNOWN); 155 msync_dbg(sdata, 156 "STA %pM : offset was invalid, t_offset=%lld\n", 157 sta->sta.addr, 158 (long long) sta->mesh->t_offset); 159 } 160 161 no_sync: 162 rcu_read_unlock(); 163 } 164 165 static void mesh_sync_offset_adjust_tsf(struct ieee80211_sub_if_data *sdata, 166 struct beacon_data *beacon) 167 { 168 struct ieee80211_if_mesh *ifmsh = &sdata->u.mesh; 169 170 WARN_ON(ifmsh->mesh_sp_id != IEEE80211_SYNC_METHOD_NEIGHBOR_OFFSET); 171 WARN_ON(!rcu_read_lock_held()); 172 173 spin_lock_bh(&ifmsh->sync_offset_lock); 174 175 if (ifmsh->sync_offset_clockdrift_max > TOFFSET_MINIMUM_ADJUSTMENT) { 176 /* Since ajusting the tsf here would 177 * require a possibly blocking call 178 * to the driver tsf setter, we punt 179 * the tsf adjustment to the mesh tasklet 180 */ 181 msync_dbg(sdata, 182 "TSF : kicking off TSF adjustment with clockdrift_max=%lld\n", 183 ifmsh->sync_offset_clockdrift_max); 184 set_bit(MESH_WORK_DRIFT_ADJUST, &ifmsh->wrkq_flags); 185 } else { 186 msync_dbg(sdata, 187 "TSF : max clockdrift=%lld; too small to adjust\n", 188 (long long)ifmsh->sync_offset_clockdrift_max); 189 ifmsh->sync_offset_clockdrift_max = 0; 190 } 191 spin_unlock_bh(&ifmsh->sync_offset_lock); 192 } 193 194 static const struct sync_method sync_methods[] = { 195 { 196 .method = IEEE80211_SYNC_METHOD_NEIGHBOR_OFFSET, 197 .ops = { 198 .rx_bcn_presp = &mesh_sync_offset_rx_bcn_presp, 199 .adjust_tsf = &mesh_sync_offset_adjust_tsf, 200 } 201 }, 202 }; 203 204 const struct ieee80211_mesh_sync_ops *ieee80211_mesh_sync_ops_get(u8 method) 205 { 206 int i; 207 208 for (i = 0 ; i < ARRAY_SIZE(sync_methods); ++i) { 209 if (sync_methods[i].method == method) 210 return &sync_methods[i].ops; 211 } 212 return NULL; 213 } 214