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) 2021,2023 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 * Returns: If the mesh peer is currently adjusting its TBTT 42 */ 43 static bool mesh_peer_tbtt_adjusting(const struct ieee80211_meshconf_ie *cfg) 44 { 45 return cfg && 46 (cfg->meshconf_cap & IEEE80211_MESHCONF_CAPAB_TBTT_ADJUSTING); 47 } 48 49 void mesh_sync_adjust_tsf(struct ieee80211_sub_if_data *sdata) 50 { 51 struct ieee80211_local *local = sdata->local; 52 struct ieee80211_if_mesh *ifmsh = &sdata->u.mesh; 53 /* sdata->vif.bss_conf.beacon_int in 1024us units, 0.04% */ 54 u64 beacon_int_fraction = sdata->vif.bss_conf.beacon_int * 1024 / 2500; 55 u64 tsf; 56 u64 tsfdelta; 57 58 spin_lock_bh(&ifmsh->sync_offset_lock); 59 if (ifmsh->sync_offset_clockdrift_max < beacon_int_fraction) { 60 msync_dbg(sdata, "TSF : max clockdrift=%lld; adjusting\n", 61 (long long) ifmsh->sync_offset_clockdrift_max); 62 tsfdelta = -ifmsh->sync_offset_clockdrift_max; 63 ifmsh->sync_offset_clockdrift_max = 0; 64 } else { 65 msync_dbg(sdata, "TSF : max clockdrift=%lld; adjusting by %llu\n", 66 (long long) ifmsh->sync_offset_clockdrift_max, 67 (unsigned long long) beacon_int_fraction); 68 tsfdelta = -beacon_int_fraction; 69 ifmsh->sync_offset_clockdrift_max -= beacon_int_fraction; 70 } 71 spin_unlock_bh(&ifmsh->sync_offset_lock); 72 73 if (local->ops->offset_tsf) { 74 drv_offset_tsf(local, sdata, tsfdelta); 75 } else { 76 tsf = drv_get_tsf(local, sdata); 77 if (tsf != -1ULL) 78 drv_set_tsf(local, sdata, tsf + tsfdelta); 79 } 80 } 81 82 static void 83 mesh_sync_offset_rx_bcn_presp(struct ieee80211_sub_if_data *sdata, u16 stype, 84 struct ieee80211_mgmt *mgmt, unsigned int len, 85 const struct ieee80211_meshconf_ie *mesh_cfg, 86 struct ieee80211_rx_status *rx_status) 87 { 88 struct ieee80211_if_mesh *ifmsh = &sdata->u.mesh; 89 struct ieee80211_local *local = sdata->local; 90 struct sta_info *sta; 91 u64 t_t, t_r; 92 93 WARN_ON(ifmsh->mesh_sp_id != IEEE80211_SYNC_METHOD_NEIGHBOR_OFFSET); 94 95 /* standard mentions only beacons */ 96 if (stype != IEEE80211_STYPE_BEACON) 97 return; 98 99 /* 100 * Get time when timestamp field was received. If we don't 101 * have rx timestamps, then use current tsf as an approximation. 102 * drv_get_tsf() must be called before entering the rcu-read 103 * section. 104 */ 105 if (ieee80211_have_rx_timestamp(rx_status)) 106 t_r = ieee80211_calculate_rx_timestamp(local, rx_status, 107 len + FCS_LEN, 24); 108 else 109 t_r = drv_get_tsf(local, sdata); 110 111 rcu_read_lock(); 112 sta = sta_info_get(sdata, mgmt->sa); 113 if (!sta) 114 goto no_sync; 115 116 /* check offset sync conditions (13.13.2.2.1) 117 * 118 * TODO also sync to 119 * dot11MeshNbrOffsetMaxNeighbor non-peer non-MBSS neighbors 120 */ 121 122 if (mesh_peer_tbtt_adjusting(mesh_cfg)) { 123 msync_dbg(sdata, "STA %pM : is adjusting TBTT\n", 124 sta->sta.addr); 125 goto no_sync; 126 } 127 128 /* Timing offset calculation (see 13.13.2.2.2) */ 129 t_t = le64_to_cpu(mgmt->u.beacon.timestamp); 130 sta->mesh->t_offset = t_t - t_r; 131 132 if (test_sta_flag(sta, WLAN_STA_TOFFSET_KNOWN)) { 133 s64 t_clockdrift = sta->mesh->t_offset_setpoint - sta->mesh->t_offset; 134 msync_dbg(sdata, 135 "STA %pM : t_offset=%lld, t_offset_setpoint=%lld, t_clockdrift=%lld\n", 136 sta->sta.addr, (long long) sta->mesh->t_offset, 137 (long long) sta->mesh->t_offset_setpoint, 138 (long long) t_clockdrift); 139 140 if (t_clockdrift > TOFFSET_MAXIMUM_ADJUSTMENT || 141 t_clockdrift < -TOFFSET_MAXIMUM_ADJUSTMENT) { 142 msync_dbg(sdata, 143 "STA %pM : t_clockdrift=%lld too large, setpoint reset\n", 144 sta->sta.addr, 145 (long long) t_clockdrift); 146 clear_sta_flag(sta, WLAN_STA_TOFFSET_KNOWN); 147 goto no_sync; 148 } 149 150 spin_lock_bh(&ifmsh->sync_offset_lock); 151 if (t_clockdrift > ifmsh->sync_offset_clockdrift_max) 152 ifmsh->sync_offset_clockdrift_max = t_clockdrift; 153 spin_unlock_bh(&ifmsh->sync_offset_lock); 154 } else { 155 sta->mesh->t_offset_setpoint = sta->mesh->t_offset - TOFFSET_SET_MARGIN; 156 set_sta_flag(sta, WLAN_STA_TOFFSET_KNOWN); 157 msync_dbg(sdata, 158 "STA %pM : offset was invalid, t_offset=%lld\n", 159 sta->sta.addr, 160 (long long) sta->mesh->t_offset); 161 } 162 163 no_sync: 164 rcu_read_unlock(); 165 } 166 167 static void mesh_sync_offset_adjust_tsf(struct ieee80211_sub_if_data *sdata, 168 struct beacon_data *beacon) 169 { 170 struct ieee80211_if_mesh *ifmsh = &sdata->u.mesh; 171 172 WARN_ON(ifmsh->mesh_sp_id != IEEE80211_SYNC_METHOD_NEIGHBOR_OFFSET); 173 WARN_ON(!rcu_read_lock_held()); 174 175 spin_lock_bh(&ifmsh->sync_offset_lock); 176 177 if (ifmsh->sync_offset_clockdrift_max > TOFFSET_MINIMUM_ADJUSTMENT) { 178 /* Since ajusting the tsf here would 179 * require a possibly blocking call 180 * to the driver tsf setter, we punt 181 * the tsf adjustment to the mesh tasklet 182 */ 183 msync_dbg(sdata, 184 "TSF : kicking off TSF adjustment with clockdrift_max=%lld\n", 185 ifmsh->sync_offset_clockdrift_max); 186 set_bit(MESH_WORK_DRIFT_ADJUST, &ifmsh->wrkq_flags); 187 } else { 188 msync_dbg(sdata, 189 "TSF : max clockdrift=%lld; too small to adjust\n", 190 (long long)ifmsh->sync_offset_clockdrift_max); 191 ifmsh->sync_offset_clockdrift_max = 0; 192 } 193 spin_unlock_bh(&ifmsh->sync_offset_lock); 194 } 195 196 static const struct sync_method sync_methods[] = { 197 { 198 .method = IEEE80211_SYNC_METHOD_NEIGHBOR_OFFSET, 199 .ops = { 200 .rx_bcn_presp = &mesh_sync_offset_rx_bcn_presp, 201 .adjust_tsf = &mesh_sync_offset_adjust_tsf, 202 } 203 }, 204 }; 205 206 const struct ieee80211_mesh_sync_ops *ieee80211_mesh_sync_ops_get(u8 method) 207 { 208 int i; 209 210 for (i = 0 ; i < ARRAY_SIZE(sync_methods); ++i) { 211 if (sync_methods[i].method == method) 212 return &sync_methods[i].ops; 213 } 214 return NULL; 215 } 216