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dbf498fb JC |
1 | /* |
2 | * Copyright 2011-2012, Pavel Zubarev <pavel.zubarev@gmail.com> | |
3 | * Copyright 2011-2012, Marco Porsch <marco.porsch@s2005.tu-chemnitz.de> | |
4 | * Copyright 2011-2012, cozybit Inc. | |
5 | * | |
6 | * This program is free software; you can redistribute it and/or modify | |
7 | * it under the terms of the GNU General Public License version 2 as | |
8 | * published by the Free Software Foundation. | |
9 | */ | |
10 | ||
11 | #include "ieee80211_i.h" | |
12 | #include "mesh.h" | |
13 | #include "driver-ops.h" | |
14 | ||
445cd452 | 15 | /* This is not in the standard. It represents a tolerable tsf drift below |
dbf498fb JC |
16 | * which we do no TSF adjustment. |
17 | */ | |
a802a6eb JC |
18 | #define TOFFSET_MINIMUM_ADJUSTMENT 10 |
19 | ||
ec14bcd2 JC |
20 | /* This is not in the standard. It is a margin added to the |
21 | * Toffset setpoint to mitigate TSF overcorrection | |
22 | * introduced by TSF adjustment latency. | |
23 | */ | |
24 | #define TOFFSET_SET_MARGIN 20 | |
25 | ||
a802a6eb JC |
26 | /* This is not in the standard. It represents the maximum Toffset jump above |
27 | * which we'll invalidate the Toffset setpoint and choose a new setpoint. This | |
28 | * could be, for instance, in case a neighbor is restarted and its TSF counter | |
29 | * reset. | |
ec14bcd2 | 30 | */ |
3a53731d | 31 | #define TOFFSET_MAXIMUM_ADJUSTMENT 800 /* 0.8 ms */ |
dbf498fb JC |
32 | |
33 | struct sync_method { | |
34 | u8 method; | |
35 | struct ieee80211_mesh_sync_ops ops; | |
36 | }; | |
37 | ||
38 | /** | |
39 | * mesh_peer_tbtt_adjusting - check if an mp is currently adjusting its TBTT | |
40 | * | |
41 | * @ie: information elements of a management frame from the mesh peer | |
42 | */ | |
43 | static bool mesh_peer_tbtt_adjusting(struct ieee802_11_elems *ie) | |
44 | { | |
45 | return (ie->mesh_config->meshconf_cap & | |
bf7cd94d | 46 | IEEE80211_MESHCONF_CAPAB_TBTT_ADJUSTING) != 0; |
dbf498fb JC |
47 | } |
48 | ||
445cd452 | 49 | void mesh_sync_adjust_tsf(struct ieee80211_sub_if_data *sdata) |
dbf498fb JC |
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); | |
dbf498fb | 59 | if (ifmsh->sync_offset_clockdrift_max < beacon_int_fraction) { |
445cd452 | 60 | msync_dbg(sdata, "TSF : max clockdrift=%lld; adjusting\n", |
bdcbd8e0 | 61 | (long long) ifmsh->sync_offset_clockdrift_max); |
dbf498fb JC |
62 | tsfdelta = -ifmsh->sync_offset_clockdrift_max; |
63 | ifmsh->sync_offset_clockdrift_max = 0; | |
64 | } else { | |
445cd452 | 65 | msync_dbg(sdata, "TSF : max clockdrift=%lld; adjusting by %llu\n", |
bdcbd8e0 JB |
66 | (long long) ifmsh->sync_offset_clockdrift_max, |
67 | (unsigned long long) beacon_int_fraction); | |
dbf498fb JC |
68 | tsfdelta = -beacon_int_fraction; |
69 | ifmsh->sync_offset_clockdrift_max -= beacon_int_fraction; | |
70 | } | |
55fabefe | 71 | spin_unlock_bh(&ifmsh->sync_offset_lock); |
dbf498fb | 72 | |
354d381b PT |
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 | } | |
dbf498fb JC |
80 | } |
81 | ||
82 | static void mesh_sync_offset_rx_bcn_presp(struct ieee80211_sub_if_data *sdata, | |
83 | u16 stype, | |
84 | struct ieee80211_mgmt *mgmt, | |
85 | struct ieee802_11_elems *elems, | |
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 | ||
ce953204 BC |
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 | 24 + 12 + | |
108 | elems->total_len + | |
109 | FCS_LEN, | |
110 | 24); | |
111 | else | |
112 | t_r = drv_get_tsf(local, sdata); | |
dbf498fb JC |
113 | |
114 | rcu_read_lock(); | |
115 | sta = sta_info_get(sdata, mgmt->sa); | |
116 | if (!sta) | |
117 | goto no_sync; | |
118 | ||
119 | /* check offset sync conditions (13.13.2.2.1) | |
120 | * | |
121 | * TODO also sync to | |
122 | * dot11MeshNbrOffsetMaxNeighbor non-peer non-MBSS neighbors | |
123 | */ | |
124 | ||
125 | if (elems->mesh_config && mesh_peer_tbtt_adjusting(elems)) { | |
bf7cd94d JB |
126 | msync_dbg(sdata, "STA %pM : is adjusting TBTT\n", |
127 | sta->sta.addr); | |
dbf498fb JC |
128 | goto no_sync; |
129 | } | |
130 | ||
dbf498fb JC |
131 | /* Timing offset calculation (see 13.13.2.2.2) */ |
132 | t_t = le64_to_cpu(mgmt->u.beacon.timestamp); | |
433f5bc1 | 133 | sta->mesh->t_offset = t_t - t_r; |
dbf498fb JC |
134 | |
135 | if (test_sta_flag(sta, WLAN_STA_TOFFSET_KNOWN)) { | |
433f5bc1 | 136 | s64 t_clockdrift = sta->mesh->t_offset_setpoint - sta->mesh->t_offset; |
bdcbd8e0 | 137 | msync_dbg(sdata, |
433f5bc1 JB |
138 | "STA %pM : t_offset=%lld, t_offset_setpoint=%lld, t_clockdrift=%lld\n", |
139 | sta->sta.addr, (long long) sta->mesh->t_offset, | |
140 | (long long) sta->mesh->t_offset_setpoint, | |
dbf498fb | 141 | (long long) t_clockdrift); |
a802a6eb JC |
142 | |
143 | if (t_clockdrift > TOFFSET_MAXIMUM_ADJUSTMENT || | |
bf7cd94d | 144 | t_clockdrift < -TOFFSET_MAXIMUM_ADJUSTMENT) { |
bdcbd8e0 JB |
145 | msync_dbg(sdata, |
146 | "STA %pM : t_clockdrift=%lld too large, setpoint reset\n", | |
a802a6eb JC |
147 | sta->sta.addr, |
148 | (long long) t_clockdrift); | |
149 | clear_sta_flag(sta, WLAN_STA_TOFFSET_KNOWN); | |
150 | goto no_sync; | |
151 | } | |
152 | ||
dbf498fb | 153 | spin_lock_bh(&ifmsh->sync_offset_lock); |
bf7cd94d JB |
154 | if (t_clockdrift > ifmsh->sync_offset_clockdrift_max) |
155 | ifmsh->sync_offset_clockdrift_max = t_clockdrift; | |
dbf498fb | 156 | spin_unlock_bh(&ifmsh->sync_offset_lock); |
dbf498fb | 157 | } else { |
433f5bc1 | 158 | sta->mesh->t_offset_setpoint = sta->mesh->t_offset - TOFFSET_SET_MARGIN; |
dbf498fb | 159 | set_sta_flag(sta, WLAN_STA_TOFFSET_KNOWN); |
bdcbd8e0 | 160 | msync_dbg(sdata, |
433f5bc1 | 161 | "STA %pM : offset was invalid, t_offset=%lld\n", |
dbf498fb | 162 | sta->sta.addr, |
433f5bc1 | 163 | (long long) sta->mesh->t_offset); |
dbf498fb | 164 | } |
dbf498fb JC |
165 | |
166 | no_sync: | |
167 | rcu_read_unlock(); | |
168 | } | |
169 | ||
445cd452 | 170 | static void mesh_sync_offset_adjust_tsf(struct ieee80211_sub_if_data *sdata, |
43552be1 | 171 | struct beacon_data *beacon) |
dbf498fb JC |
172 | { |
173 | struct ieee80211_if_mesh *ifmsh = &sdata->u.mesh; | |
174 | ||
bf7cd94d | 175 | WARN_ON(ifmsh->mesh_sp_id != IEEE80211_SYNC_METHOD_NEIGHBOR_OFFSET); |
8c5bb1fa | 176 | WARN_ON(!rcu_read_lock_held()); |
dbf498fb JC |
177 | |
178 | spin_lock_bh(&ifmsh->sync_offset_lock); | |
179 | ||
bf7cd94d | 180 | if (ifmsh->sync_offset_clockdrift_max > TOFFSET_MINIMUM_ADJUSTMENT) { |
dbf498fb JC |
181 | /* Since ajusting the tsf here would |
182 | * require a possibly blocking call | |
183 | * to the driver tsf setter, we punt | |
184 | * the tsf adjustment to the mesh tasklet | |
185 | */ | |
bdcbd8e0 | 186 | msync_dbg(sdata, |
445cd452 | 187 | "TSF : kicking off TSF adjustment with clockdrift_max=%lld\n", |
bdcbd8e0 | 188 | ifmsh->sync_offset_clockdrift_max); |
bf7cd94d | 189 | set_bit(MESH_WORK_DRIFT_ADJUST, &ifmsh->wrkq_flags); |
dbf498fb | 190 | } else { |
bdcbd8e0 | 191 | msync_dbg(sdata, |
445cd452 | 192 | "TSF : max clockdrift=%lld; too small to adjust\n", |
bdcbd8e0 | 193 | (long long)ifmsh->sync_offset_clockdrift_max); |
dbf498fb JC |
194 | ifmsh->sync_offset_clockdrift_max = 0; |
195 | } | |
196 | spin_unlock_bh(&ifmsh->sync_offset_lock); | |
197 | } | |
198 | ||
8ba7acf3 | 199 | static const struct sync_method sync_methods[] = { |
dbf498fb JC |
200 | { |
201 | .method = IEEE80211_SYNC_METHOD_NEIGHBOR_OFFSET, | |
202 | .ops = { | |
203 | .rx_bcn_presp = &mesh_sync_offset_rx_bcn_presp, | |
445cd452 | 204 | .adjust_tsf = &mesh_sync_offset_adjust_tsf, |
dbf498fb JC |
205 | } |
206 | }, | |
dbf498fb JC |
207 | }; |
208 | ||
8ba7acf3 | 209 | const struct ieee80211_mesh_sync_ops *ieee80211_mesh_sync_ops_get(u8 method) |
dbf498fb | 210 | { |
bf7cd94d | 211 | int i; |
dbf498fb JC |
212 | |
213 | for (i = 0 ; i < ARRAY_SIZE(sync_methods); ++i) { | |
bf7cd94d JB |
214 | if (sync_methods[i].method == method) |
215 | return &sync_methods[i].ops; | |
dbf498fb | 216 | } |
bf7cd94d | 217 | return NULL; |
dbf498fb | 218 | } |