blob: aa8d1e437385599de915988444f89448b5bba02f [file] [log] [blame]
Javier Cardonadbf498f2012-03-31 11:31:32 -07001/*
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
Javier Cardonadbf498f2012-03-31 11:31:32 -070015/* This is not in the standard. It represents a tolerable tbtt drift below
16 * which we do no TSF adjustment.
17 */
Javier Cardonaa802a6e2012-04-12 14:32:22 -070018#define TOFFSET_MINIMUM_ADJUSTMENT 10
19
Javier Cardonaec14bcd2012-04-12 14:32:23 -070020/* 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
Javier Cardonaa802a6e2012-04-12 14:32:22 -070026/* 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.
Javier Cardonaec14bcd2012-04-12 14:32:23 -070030 */
Javier Cardonaa802a6e2012-04-12 14:32:22 -070031#define TOFFSET_MAXIMUM_ADJUSTMENT 30000 /* 30 ms */
Javier Cardonadbf498f2012-03-31 11:31:32 -070032
33struct 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 */
43static bool mesh_peer_tbtt_adjusting(struct ieee802_11_elems *ie)
44{
45 return (ie->mesh_config->meshconf_cap &
Marco Porsch65821632012-11-21 18:40:30 -080046 IEEE80211_MESHCONF_CAPAB_TBTT_ADJUSTING) != 0;
Javier Cardonadbf498f2012-03-31 11:31:32 -070047}
48
49void 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);
Javier Cardonadbf498f2012-03-31 11:31:32 -070059 if (ifmsh->sync_offset_clockdrift_max < beacon_int_fraction) {
Johannes Bergbdcbd8e2012-06-22 11:29:50 +020060 msync_dbg(sdata, "TBTT : max clockdrift=%lld; adjusting\n",
61 (long long) ifmsh->sync_offset_clockdrift_max);
Javier Cardonadbf498f2012-03-31 11:31:32 -070062 tsfdelta = -ifmsh->sync_offset_clockdrift_max;
63 ifmsh->sync_offset_clockdrift_max = 0;
64 } else {
Johannes Bergbdcbd8e2012-06-22 11:29:50 +020065 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);
Javier Cardonadbf498f2012-03-31 11:31:32 -070068 tsfdelta = -beacon_int_fraction;
69 ifmsh->sync_offset_clockdrift_max -= beacon_int_fraction;
70 }
Thomas Pedersen55fabef2012-10-05 17:57:39 -070071 spin_unlock_bh(&ifmsh->sync_offset_lock);
Javier Cardonadbf498f2012-03-31 11:31:32 -070072
73 tsf = drv_get_tsf(local, sdata);
74 if (tsf != -1ULL)
75 drv_set_tsf(local, sdata, tsf + tsfdelta);
Javier Cardonadbf498f2012-03-31 11:31:32 -070076}
77
78static 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);
Johannes Bergbdcbd8e2012-06-22 11:29:50 +0200115 msync_dbg(sdata, "STA %pM : is adjusting TBTT\n", sta->sta.addr);
Javier Cardonadbf498f2012-03-31 11:31:32 -0700116 goto no_sync;
117 }
118
Thomas Pedersenf4bda332012-11-13 10:46:27 -0800119 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);
Javier Cardonadbf498f2012-03-31 11:31:32 -0700126
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;
Johannes Bergbdcbd8e2012-06-22 11:29:50 +0200134 msync_dbg(sdata,
135 "STA %pM : sta->t_offset=%lld, sta->t_offset_setpoint=%lld, t_clockdrift=%lld\n",
Javier Cardonadbf498f2012-03-31 11:31:32 -0700136 sta->sta.addr,
137 (long long) sta->t_offset,
138 (long long)
139 sta->t_offset_setpoint,
140 (long long) t_clockdrift);
Javier Cardonaa802a6e2012-04-12 14:32:22 -0700141
142 if (t_clockdrift > TOFFSET_MAXIMUM_ADJUSTMENT ||
143 t_clockdrift < -TOFFSET_MAXIMUM_ADJUSTMENT) {
Johannes Bergbdcbd8e2012-06-22 11:29:50 +0200144 msync_dbg(sdata,
145 "STA %pM : t_clockdrift=%lld too large, setpoint reset\n",
Javier Cardonaa802a6e2012-04-12 14:32:22 -0700146 sta->sta.addr,
147 (long long) t_clockdrift);
148 clear_sta_flag(sta, WLAN_STA_TOFFSET_KNOWN);
149 goto no_sync;
150 }
151
Javier Cardonadbf498f2012-03-31 11:31:32 -0700152 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 {
Javier Cardona6ac95b52012-04-20 09:52:56 -0700162 sta->t_offset_setpoint = sta->t_offset - TOFFSET_SET_MARGIN;
Javier Cardonadbf498f2012-03-31 11:31:32 -0700163 set_sta_flag(sta, WLAN_STA_TOFFSET_KNOWN);
Johannes Bergbdcbd8e2012-06-22 11:29:50 +0200164 msync_dbg(sdata,
165 "STA %pM : offset was invalid, sta->t_offset=%lld\n",
Javier Cardonadbf498f2012-03-31 11:31:32 -0700166 sta->sta.addr,
167 (long long) sta->t_offset);
168 rcu_read_unlock();
169 }
170 return;
171
172no_sync:
173 rcu_read_unlock();
174}
175
176static 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 >
Javier Cardonaa802a6e2012-04-12 14:32:22 -0700187 TOFFSET_MINIMUM_ADJUSTMENT) {
Javier Cardonadbf498f2012-03-31 11:31:32 -0700188 /* 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 */
Johannes Bergbdcbd8e2012-06-22 11:29:50 +0200193 msync_dbg(sdata,
194 "TBTT : kicking off TBTT adjustment with clockdrift_max=%lld\n",
195 ifmsh->sync_offset_clockdrift_max);
Javier Cardonadbf498f2012-03-31 11:31:32 -0700196 set_bit(MESH_WORK_DRIFT_ADJUST,
197 &ifmsh->wrkq_flags);
Marco Porsch37203902012-11-23 12:23:18 -0800198
199 ifmsh->adjusting_tbtt = true;
Javier Cardonadbf498f2012-03-31 11:31:32 -0700200 } else {
Johannes Bergbdcbd8e2012-06-22 11:29:50 +0200201 msync_dbg(sdata,
202 "TBTT : max clockdrift=%lld; too small to adjust\n",
203 (long long)ifmsh->sync_offset_clockdrift_max);
Javier Cardonadbf498f2012-03-31 11:31:32 -0700204 ifmsh->sync_offset_clockdrift_max = 0;
Marco Porsch37203902012-11-23 12:23:18 -0800205
206 ifmsh->adjusting_tbtt = false;
Javier Cardonadbf498f2012-03-31 11:31:32 -0700207 }
208 spin_unlock_bh(&ifmsh->sync_offset_lock);
209}
210
Johannes Berg8ba7acf2012-09-30 17:07:19 +0200211static const struct sync_method sync_methods[] = {
Javier Cardonadbf498f2012-03-31 11:31:32 -0700212 {
213 .method = IEEE80211_SYNC_METHOD_NEIGHBOR_OFFSET,
214 .ops = {
215 .rx_bcn_presp = &mesh_sync_offset_rx_bcn_presp,
216 .adjust_tbtt = &mesh_sync_offset_adjust_tbtt,
217 }
218 },
Javier Cardonadbf498f2012-03-31 11:31:32 -0700219};
220
Johannes Berg8ba7acf2012-09-30 17:07:19 +0200221const struct ieee80211_mesh_sync_ops *ieee80211_mesh_sync_ops_get(u8 method)
Javier Cardonadbf498f2012-03-31 11:31:32 -0700222{
Johannes Berg8ba7acf2012-09-30 17:07:19 +0200223 const struct ieee80211_mesh_sync_ops *ops = NULL;
Javier Cardonadbf498f2012-03-31 11:31:32 -0700224 u8 i;
225
226 for (i = 0 ; i < ARRAY_SIZE(sync_methods); ++i) {
227 if (sync_methods[i].method == method) {
228 ops = &sync_methods[i].ops;
229 break;
230 }
231 }
232 return ops;
233}