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 */ 7 8 #include "ieee80211_i.h" 9 #include "mesh.h" 10 #include "driver-ops.h" 11 12 /* This is not in the standard. It represents a tolerable tsf drift below 13 * which we do no TSF adjustment. 14 */ 15 #define TOFFSET_MINIMUM_ADJUSTMENT 10 16 17 /* This is not in the standard. It is a margin added to the 18 * Toffset setpoint to mitigate TSF overcorrection 19 * introduced by TSF adjustment latency. 20 */ 21 #define TOFFSET_SET_MARGIN 20 22 23 /* This is not in the standard. It represents the maximum Toffset jump above 24 * which we'll invalidate the Toffset setpoint and choose a new setpoint. This 25 * could be, for instance, in case a neighbor is restarted and its TSF counter 26 * reset. 27 */ 28 #define TOFFSET_MAXIMUM_ADJUSTMENT 800 /* 0.8 ms */ 29 30 struct sync_method { 31 u8 method; 32 struct ieee80211_mesh_sync_ops ops; 33 }; 34 35 /** 36 * mesh_peer_tbtt_adjusting - check if an mp is currently adjusting its TBTT 37 * 38 * @ie: information elements of a management frame from the mesh peer 39 */ 40 static bool mesh_peer_tbtt_adjusting(struct ieee802_11_elems *ie) 41 { 42 return (ie->mesh_config->meshconf_cap & 43 IEEE80211_MESHCONF_CAPAB_TBTT_ADJUSTING) != 0; 44 } 45 46 void mesh_sync_adjust_tsf(struct ieee80211_sub_if_data *sdata) 47 { 48 struct ieee80211_local *local = sdata->local; 49 struct ieee80211_if_mesh *ifmsh = &sdata->u.mesh; 50 /* sdata->vif.bss_conf.beacon_int in 1024us units, 0.04% */ 51 u64 beacon_int_fraction = sdata->vif.bss_conf.beacon_int * 1024 / 2500; 52 u64 tsf; 53 u64 tsfdelta; 54 55 spin_lock_bh(&ifmsh->sync_offset_lock); 56 if (ifmsh->sync_offset_clockdrift_max < beacon_int_fraction) { 57 msync_dbg(sdata, "TSF : max clockdrift=%lld; adjusting\n", 58 (long long) ifmsh->sync_offset_clockdrift_max); 59 tsfdelta = -ifmsh->sync_offset_clockdrift_max; 60 ifmsh->sync_offset_clockdrift_max = 0; 61 } else { 62 msync_dbg(sdata, "TSF : max clockdrift=%lld; adjusting by %llu\n", 63 (long long) ifmsh->sync_offset_clockdrift_max, 64 (unsigned long long) beacon_int_fraction); 65 tsfdelta = -beacon_int_fraction; 66 ifmsh->sync_offset_clockdrift_max -= beacon_int_fraction; 67 } 68 spin_unlock_bh(&ifmsh->sync_offset_lock); 69 70 if (local->ops->offset_tsf) { 71 drv_offset_tsf(local, sdata, tsfdelta); 72 } else { 73 tsf = drv_get_tsf(local, sdata); 74 if (tsf != -1ULL) 75 drv_set_tsf(local, sdata, tsf + tsfdelta); 76 } 77 } 78 79 static void mesh_sync_offset_rx_bcn_presp(struct ieee80211_sub_if_data *sdata, 80 u16 stype, 81 struct ieee80211_mgmt *mgmt, 82 struct ieee802_11_elems *elems, 83 struct ieee80211_rx_status *rx_status) 84 { 85 struct ieee80211_if_mesh *ifmsh = &sdata->u.mesh; 86 struct ieee80211_local *local = sdata->local; 87 struct sta_info *sta; 88 u64 t_t, t_r; 89 90 WARN_ON(ifmsh->mesh_sp_id != IEEE80211_SYNC_METHOD_NEIGHBOR_OFFSET); 91 92 /* standard mentions only beacons */ 93 if (stype != IEEE80211_STYPE_BEACON) 94 return; 95 96 /* 97 * Get time when timestamp field was received. If we don't 98 * have rx timestamps, then use current tsf as an approximation. 99 * drv_get_tsf() must be called before entering the rcu-read 100 * section. 101 */ 102 if (ieee80211_have_rx_timestamp(rx_status)) 103 t_r = ieee80211_calculate_rx_timestamp(local, rx_status, 104 24 + 12 + 105 elems->total_len + 106 FCS_LEN, 107 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 (elems->mesh_config && mesh_peer_tbtt_adjusting(elems)) { 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