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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 | ||
dbf498fb JC |
15 | /* This is not in the standard. It represents a tolerable tbtt drift below |
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 | */ |
a802a6eb | 31 | #define TOFFSET_MAXIMUM_ADJUSTMENT 30000 /* 30 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 & | |
46 | MESHCONF_CAPAB_TBTT_ADJUSTING) != 0; | |
47 | } | |
48 | ||
49 | void mesh_sync_adjust_tbtt(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); | |
dbf498fb | 59 | if (ifmsh->sync_offset_clockdrift_max < beacon_int_fraction) { |
bdcbd8e0 JB |
60 | msync_dbg(sdata, "TBTT : max clockdrift=%lld; adjusting\n", |
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 { | |
bdcbd8e0 JB |
65 | msync_dbg(sdata, "TBTT : max clockdrift=%lld; adjusting by %llu\n", |
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 JC |
72 | |
73 | tsf = drv_get_tsf(local, sdata); | |
74 | if (tsf != -1ULL) | |
75 | drv_set_tsf(local, sdata, tsf + tsfdelta); | |
dbf498fb JC |
76 | } |
77 | ||
78 | static void mesh_sync_offset_rx_bcn_presp(struct ieee80211_sub_if_data *sdata, | |
79 | u16 stype, | |
80 | struct ieee80211_mgmt *mgmt, | |
81 | struct ieee802_11_elems *elems, | |
82 | struct ieee80211_rx_status *rx_status) | |
83 | { | |
84 | struct ieee80211_if_mesh *ifmsh = &sdata->u.mesh; | |
85 | struct ieee80211_local *local = sdata->local; | |
86 | struct sta_info *sta; | |
87 | u64 t_t, t_r; | |
88 | ||
89 | WARN_ON(ifmsh->mesh_sp_id != IEEE80211_SYNC_METHOD_NEIGHBOR_OFFSET); | |
90 | ||
91 | /* standard mentions only beacons */ | |
92 | if (stype != IEEE80211_STYPE_BEACON) | |
93 | return; | |
94 | ||
95 | /* The current tsf is a first approximation for the timestamp | |
96 | * for the received beacon. Further down we try to get a | |
97 | * better value from the rx_status->mactime field if | |
98 | * available. Also we have to call drv_get_tsf() before | |
99 | * entering the rcu-read section.*/ | |
100 | t_r = drv_get_tsf(local, sdata); | |
101 | ||
102 | rcu_read_lock(); | |
103 | sta = sta_info_get(sdata, mgmt->sa); | |
104 | if (!sta) | |
105 | goto no_sync; | |
106 | ||
107 | /* check offset sync conditions (13.13.2.2.1) | |
108 | * | |
109 | * TODO also sync to | |
110 | * dot11MeshNbrOffsetMaxNeighbor non-peer non-MBSS neighbors | |
111 | */ | |
112 | ||
113 | if (elems->mesh_config && mesh_peer_tbtt_adjusting(elems)) { | |
114 | clear_sta_flag(sta, WLAN_STA_TOFFSET_KNOWN); | |
bdcbd8e0 | 115 | msync_dbg(sdata, "STA %pM : is adjusting TBTT\n", sta->sta.addr); |
dbf498fb JC |
116 | goto no_sync; |
117 | } | |
118 | ||
f4bda337 TP |
119 | if (ieee80211_have_rx_timestamp(rx_status)) |
120 | /* time when timestamp field was received */ | |
121 | t_r = ieee80211_calculate_rx_timestamp(local, rx_status, | |
122 | 24 + 12 + | |
123 | elems->total_len + | |
124 | FCS_LEN, | |
125 | 24); | |
dbf498fb JC |
126 | |
127 | /* Timing offset calculation (see 13.13.2.2.2) */ | |
128 | t_t = le64_to_cpu(mgmt->u.beacon.timestamp); | |
129 | sta->t_offset = t_t - t_r; | |
130 | ||
131 | if (test_sta_flag(sta, WLAN_STA_TOFFSET_KNOWN)) { | |
132 | s64 t_clockdrift = sta->t_offset_setpoint | |
133 | - sta->t_offset; | |
bdcbd8e0 JB |
134 | msync_dbg(sdata, |
135 | "STA %pM : sta->t_offset=%lld, sta->t_offset_setpoint=%lld, t_clockdrift=%lld\n", | |
dbf498fb JC |
136 | sta->sta.addr, |
137 | (long long) sta->t_offset, | |
138 | (long long) | |
139 | sta->t_offset_setpoint, | |
140 | (long long) t_clockdrift); | |
a802a6eb JC |
141 | |
142 | if (t_clockdrift > TOFFSET_MAXIMUM_ADJUSTMENT || | |
143 | t_clockdrift < -TOFFSET_MAXIMUM_ADJUSTMENT) { | |
bdcbd8e0 JB |
144 | msync_dbg(sdata, |
145 | "STA %pM : t_clockdrift=%lld too large, setpoint reset\n", | |
a802a6eb JC |
146 | sta->sta.addr, |
147 | (long long) t_clockdrift); | |
148 | clear_sta_flag(sta, WLAN_STA_TOFFSET_KNOWN); | |
149 | goto no_sync; | |
150 | } | |
151 | ||
dbf498fb JC |
152 | rcu_read_unlock(); |
153 | ||
154 | spin_lock_bh(&ifmsh->sync_offset_lock); | |
155 | if (t_clockdrift > | |
156 | ifmsh->sync_offset_clockdrift_max) | |
157 | ifmsh->sync_offset_clockdrift_max | |
158 | = t_clockdrift; | |
159 | spin_unlock_bh(&ifmsh->sync_offset_lock); | |
160 | ||
161 | } else { | |
6ac95b57 | 162 | sta->t_offset_setpoint = sta->t_offset - TOFFSET_SET_MARGIN; |
dbf498fb | 163 | set_sta_flag(sta, WLAN_STA_TOFFSET_KNOWN); |
bdcbd8e0 JB |
164 | msync_dbg(sdata, |
165 | "STA %pM : offset was invalid, sta->t_offset=%lld\n", | |
dbf498fb JC |
166 | sta->sta.addr, |
167 | (long long) sta->t_offset); | |
168 | rcu_read_unlock(); | |
169 | } | |
170 | return; | |
171 | ||
172 | no_sync: | |
173 | rcu_read_unlock(); | |
174 | } | |
175 | ||
176 | static void mesh_sync_offset_adjust_tbtt(struct ieee80211_sub_if_data *sdata) | |
177 | { | |
178 | struct ieee80211_if_mesh *ifmsh = &sdata->u.mesh; | |
179 | ||
180 | WARN_ON(ifmsh->mesh_sp_id | |
181 | != IEEE80211_SYNC_METHOD_NEIGHBOR_OFFSET); | |
182 | BUG_ON(!rcu_read_lock_held()); | |
183 | ||
184 | spin_lock_bh(&ifmsh->sync_offset_lock); | |
185 | ||
186 | if (ifmsh->sync_offset_clockdrift_max > | |
a802a6eb | 187 | TOFFSET_MINIMUM_ADJUSTMENT) { |
dbf498fb JC |
188 | /* Since ajusting the tsf here would |
189 | * require a possibly blocking call | |
190 | * to the driver tsf setter, we punt | |
191 | * the tsf adjustment to the mesh tasklet | |
192 | */ | |
bdcbd8e0 JB |
193 | msync_dbg(sdata, |
194 | "TBTT : kicking off TBTT adjustment with clockdrift_max=%lld\n", | |
195 | ifmsh->sync_offset_clockdrift_max); | |
dbf498fb JC |
196 | set_bit(MESH_WORK_DRIFT_ADJUST, |
197 | &ifmsh->wrkq_flags); | |
198 | } else { | |
bdcbd8e0 JB |
199 | msync_dbg(sdata, |
200 | "TBTT : max clockdrift=%lld; too small to adjust\n", | |
201 | (long long)ifmsh->sync_offset_clockdrift_max); | |
dbf498fb JC |
202 | ifmsh->sync_offset_clockdrift_max = 0; |
203 | } | |
204 | spin_unlock_bh(&ifmsh->sync_offset_lock); | |
205 | } | |
206 | ||
8ba7acf3 | 207 | static const struct sync_method sync_methods[] = { |
dbf498fb JC |
208 | { |
209 | .method = IEEE80211_SYNC_METHOD_NEIGHBOR_OFFSET, | |
210 | .ops = { | |
211 | .rx_bcn_presp = &mesh_sync_offset_rx_bcn_presp, | |
212 | .adjust_tbtt = &mesh_sync_offset_adjust_tbtt, | |
213 | } | |
214 | }, | |
dbf498fb JC |
215 | }; |
216 | ||
8ba7acf3 | 217 | const struct ieee80211_mesh_sync_ops *ieee80211_mesh_sync_ops_get(u8 method) |
dbf498fb | 218 | { |
8ba7acf3 | 219 | const struct ieee80211_mesh_sync_ops *ops = NULL; |
dbf498fb JC |
220 | u8 i; |
221 | ||
222 | for (i = 0 ; i < ARRAY_SIZE(sync_methods); ++i) { | |
223 | if (sync_methods[i].method == method) { | |
224 | ops = &sync_methods[i].ops; | |
225 | break; | |
226 | } | |
227 | } | |
228 | return ops; | |
229 | } |