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(lock: &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(lock: &ifmsh->sync_offset_lock); |
72 | |
73 | if (local->ops->offset_tsf) { |
74 | drv_offset_tsf(local, sdata, offset: tsfdelta); |
75 | } else { |
76 | tsf = drv_get_tsf(local, sdata); |
77 | if (tsf != -1ULL) |
78 | drv_set_tsf(local, sdata, tsf: 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(status: rx_status)) |
106 | t_r = ieee80211_calculate_rx_timestamp(local, status: rx_status, |
107 | mpdu_len: len + FCS_LEN, mpdu_offset: 24); |
108 | else |
109 | t_r = drv_get_tsf(local, sdata); |
110 | |
111 | rcu_read_lock(); |
112 | sta = sta_info_get(sdata, addr: 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(cfg: 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, flag: 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, flag: WLAN_STA_TOFFSET_KNOWN); |
147 | goto no_sync; |
148 | } |
149 | |
150 | spin_lock_bh(lock: &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(lock: &ifmsh->sync_offset_lock); |
154 | } else { |
155 | sta->mesh->t_offset_setpoint = sta->mesh->t_offset - TOFFSET_SET_MARGIN; |
156 | set_sta_flag(sta, flag: 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(lock: &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(nr: MESH_WORK_DRIFT_ADJUST, addr: &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(lock: &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 | |