blob: 38d30e8ce6dc08f647777b6da179cc7dee56141b [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
15#ifdef CONFIG_MAC80211_VERBOSE_MESH_SYNC_DEBUG
16#define msync_dbg(fmt, args...) \
17 printk(KERN_DEBUG "Mesh sync (%s): " fmt "\n", sdata->name, ##args)
18#else
19#define msync_dbg(fmt, args...) do { (void)(0); } while (0)
20#endif
21
22/* This is not in the standard. It represents a tolerable tbtt drift below
23 * which we do no TSF adjustment.
24 */
Javier Cardonaa802a6e2012-04-12 14:32:22 -070025#define TOFFSET_MINIMUM_ADJUSTMENT 10
26
Javier Cardonaec14bcd2012-04-12 14:32:23 -070027/* This is not in the standard. It is a margin added to the
28 * Toffset setpoint to mitigate TSF overcorrection
29 * introduced by TSF adjustment latency.
30 */
31#define TOFFSET_SET_MARGIN 20
32
Javier Cardonaa802a6e2012-04-12 14:32:22 -070033/* This is not in the standard. It represents the maximum Toffset jump above
34 * which we'll invalidate the Toffset setpoint and choose a new setpoint. This
35 * could be, for instance, in case a neighbor is restarted and its TSF counter
36 * reset.
Javier Cardonaec14bcd2012-04-12 14:32:23 -070037 */
Javier Cardonaa802a6e2012-04-12 14:32:22 -070038#define TOFFSET_MAXIMUM_ADJUSTMENT 30000 /* 30 ms */
Javier Cardonadbf498f2012-03-31 11:31:32 -070039
40struct sync_method {
41 u8 method;
42 struct ieee80211_mesh_sync_ops ops;
43};
44
45/**
46 * mesh_peer_tbtt_adjusting - check if an mp is currently adjusting its TBTT
47 *
48 * @ie: information elements of a management frame from the mesh peer
49 */
50static bool mesh_peer_tbtt_adjusting(struct ieee802_11_elems *ie)
51{
52 return (ie->mesh_config->meshconf_cap &
53 MESHCONF_CAPAB_TBTT_ADJUSTING) != 0;
54}
55
56void mesh_sync_adjust_tbtt(struct ieee80211_sub_if_data *sdata)
57{
58 struct ieee80211_local *local = sdata->local;
59 struct ieee80211_if_mesh *ifmsh = &sdata->u.mesh;
60 /* sdata->vif.bss_conf.beacon_int in 1024us units, 0.04% */
61 u64 beacon_int_fraction = sdata->vif.bss_conf.beacon_int * 1024 / 2500;
62 u64 tsf;
63 u64 tsfdelta;
64
65 spin_lock_bh(&ifmsh->sync_offset_lock);
66
67 if (ifmsh->sync_offset_clockdrift_max < beacon_int_fraction) {
68 msync_dbg("TBTT : max clockdrift=%lld; adjusting",
69 (long long) ifmsh->sync_offset_clockdrift_max);
70 tsfdelta = -ifmsh->sync_offset_clockdrift_max;
71 ifmsh->sync_offset_clockdrift_max = 0;
72 } else {
73 msync_dbg("TBTT : max clockdrift=%lld; adjusting by %llu",
74 (long long) ifmsh->sync_offset_clockdrift_max,
75 (unsigned long long) beacon_int_fraction);
76 tsfdelta = -beacon_int_fraction;
77 ifmsh->sync_offset_clockdrift_max -= beacon_int_fraction;
78 }
79
80 tsf = drv_get_tsf(local, sdata);
81 if (tsf != -1ULL)
82 drv_set_tsf(local, sdata, tsf + tsfdelta);
83 spin_unlock_bh(&ifmsh->sync_offset_lock);
84}
85
86static void mesh_sync_offset_rx_bcn_presp(struct ieee80211_sub_if_data *sdata,
87 u16 stype,
88 struct ieee80211_mgmt *mgmt,
89 struct ieee802_11_elems *elems,
90 struct ieee80211_rx_status *rx_status)
91{
92 struct ieee80211_if_mesh *ifmsh = &sdata->u.mesh;
93 struct ieee80211_local *local = sdata->local;
94 struct sta_info *sta;
95 u64 t_t, t_r;
96
97 WARN_ON(ifmsh->mesh_sp_id != IEEE80211_SYNC_METHOD_NEIGHBOR_OFFSET);
98
99 /* standard mentions only beacons */
100 if (stype != IEEE80211_STYPE_BEACON)
101 return;
102
103 /* The current tsf is a first approximation for the timestamp
104 * for the received beacon. Further down we try to get a
105 * better value from the rx_status->mactime field if
106 * available. Also we have to call drv_get_tsf() before
107 * entering the rcu-read section.*/
108 t_r = drv_get_tsf(local, sdata);
109
110 rcu_read_lock();
111 sta = sta_info_get(sdata, mgmt->sa);
112 if (!sta)
113 goto no_sync;
114
115 /* check offset sync conditions (13.13.2.2.1)
116 *
117 * TODO also sync to
118 * dot11MeshNbrOffsetMaxNeighbor non-peer non-MBSS neighbors
119 */
120
121 if (elems->mesh_config && mesh_peer_tbtt_adjusting(elems)) {
122 clear_sta_flag(sta, WLAN_STA_TOFFSET_KNOWN);
123 msync_dbg("STA %pM : is adjusting TBTT", sta->sta.addr);
124 goto no_sync;
125 }
126
127 if (rx_status->flag & RX_FLAG_MACTIME_MPDU && rx_status->mactime) {
128 /*
129 * The mactime is defined as the time the first data symbol
130 * of the frame hits the PHY, and the timestamp of the beacon
131 * is defined as "the time that the data symbol containing the
132 * first bit of the timestamp is transmitted to the PHY plus
133 * the transmitting STA's delays through its local PHY from the
134 * MAC-PHY interface to its interface with the WM" (802.11
135 * 11.1.2)
136 *
137 * T_r, in 13.13.2.2.2, is just defined as "the frame reception
138 * time" but we unless we interpret that time to be the same
139 * time of the beacon timestamp, the offset calculation will be
140 * off. Below we adjust t_r to be "the time at which the first
141 * symbol of the timestamp element in the beacon is received".
142 * This correction depends on the rate.
143 *
144 * Based on similar code in ibss.c
145 */
146 int rate;
147
148 if (rx_status->flag & RX_FLAG_HT) {
149 /* TODO:
150 * In principle there could be HT-beacons (Dual Beacon
151 * HT Operation options), but for now ignore them and
152 * just use the primary (i.e. non-HT) beacons for
153 * synchronization.
154 * */
155 goto no_sync;
156 } else
157 rate = local->hw.wiphy->bands[rx_status->band]->
158 bitrates[rx_status->rate_idx].bitrate;
159
160 /* 24 bytes of header * 8 bits/byte *
161 * 10*(100 Kbps)/Mbps / rate (100 Kbps)*/
162 t_r = rx_status->mactime + (24 * 8 * 10 / rate);
163 }
164
165 /* Timing offset calculation (see 13.13.2.2.2) */
166 t_t = le64_to_cpu(mgmt->u.beacon.timestamp);
167 sta->t_offset = t_t - t_r;
168
169 if (test_sta_flag(sta, WLAN_STA_TOFFSET_KNOWN)) {
170 s64 t_clockdrift = sta->t_offset_setpoint
171 - sta->t_offset;
Javier Cardonaa802a6e2012-04-12 14:32:22 -0700172 msync_dbg("STA %pM : sta->t_offset=%lld, sta->t_offset_setpoint=%lld, t_clockdrift=%lld",
Javier Cardonadbf498f2012-03-31 11:31:32 -0700173 sta->sta.addr,
174 (long long) sta->t_offset,
175 (long long)
176 sta->t_offset_setpoint,
177 (long long) t_clockdrift);
Javier Cardonaa802a6e2012-04-12 14:32:22 -0700178
179 if (t_clockdrift > TOFFSET_MAXIMUM_ADJUSTMENT ||
180 t_clockdrift < -TOFFSET_MAXIMUM_ADJUSTMENT) {
181 msync_dbg("STA %pM : t_clockdrift=%lld too large, setpoint reset",
182 sta->sta.addr,
183 (long long) t_clockdrift);
184 clear_sta_flag(sta, WLAN_STA_TOFFSET_KNOWN);
185 goto no_sync;
186 }
187
Javier Cardonadbf498f2012-03-31 11:31:32 -0700188 rcu_read_unlock();
189
190 spin_lock_bh(&ifmsh->sync_offset_lock);
191 if (t_clockdrift >
192 ifmsh->sync_offset_clockdrift_max)
193 ifmsh->sync_offset_clockdrift_max
194 = t_clockdrift;
195 spin_unlock_bh(&ifmsh->sync_offset_lock);
196
197 } else {
Javier Cardona6ac95b52012-04-20 09:52:56 -0700198 sta->t_offset_setpoint = sta->t_offset - TOFFSET_SET_MARGIN;
Javier Cardonadbf498f2012-03-31 11:31:32 -0700199 set_sta_flag(sta, WLAN_STA_TOFFSET_KNOWN);
200 msync_dbg("STA %pM : offset was invalid, "
201 " sta->t_offset=%lld",
202 sta->sta.addr,
203 (long long) sta->t_offset);
204 rcu_read_unlock();
205 }
206 return;
207
208no_sync:
209 rcu_read_unlock();
210}
211
212static void mesh_sync_offset_adjust_tbtt(struct ieee80211_sub_if_data *sdata)
213{
214 struct ieee80211_if_mesh *ifmsh = &sdata->u.mesh;
215
216 WARN_ON(ifmsh->mesh_sp_id
217 != IEEE80211_SYNC_METHOD_NEIGHBOR_OFFSET);
218 BUG_ON(!rcu_read_lock_held());
219
220 spin_lock_bh(&ifmsh->sync_offset_lock);
221
222 if (ifmsh->sync_offset_clockdrift_max >
Javier Cardonaa802a6e2012-04-12 14:32:22 -0700223 TOFFSET_MINIMUM_ADJUSTMENT) {
Javier Cardonadbf498f2012-03-31 11:31:32 -0700224 /* Since ajusting the tsf here would
225 * require a possibly blocking call
226 * to the driver tsf setter, we punt
227 * the tsf adjustment to the mesh tasklet
228 */
229 msync_dbg("TBTT : kicking off TBTT "
230 "adjustment with "
231 "clockdrift_max=%lld",
232 ifmsh->sync_offset_clockdrift_max);
233 set_bit(MESH_WORK_DRIFT_ADJUST,
234 &ifmsh->wrkq_flags);
235 } else {
236 msync_dbg("TBTT : max clockdrift=%lld; "
237 "too small to adjust",
238 (long long)
239 ifmsh->sync_offset_clockdrift_max);
240 ifmsh->sync_offset_clockdrift_max = 0;
241 }
242 spin_unlock_bh(&ifmsh->sync_offset_lock);
243}
244
245static const u8 *mesh_get_vendor_oui(struct ieee80211_sub_if_data *sdata)
246{
247 struct ieee80211_if_mesh *ifmsh = &sdata->u.mesh;
248 u8 offset;
249
250 if (!ifmsh->ie || !ifmsh->ie_len)
251 return NULL;
252
253 offset = ieee80211_ie_split_vendor(ifmsh->ie,
254 ifmsh->ie_len, 0);
255
256 if (!offset)
257 return NULL;
258
259 return ifmsh->ie + offset + 2;
260}
261
262static void mesh_sync_vendor_rx_bcn_presp(struct ieee80211_sub_if_data *sdata,
263 u16 stype,
264 struct ieee80211_mgmt *mgmt,
265 struct ieee802_11_elems *elems,
266 struct ieee80211_rx_status *rx_status)
267{
268 const u8 *oui;
269
270 WARN_ON(sdata->u.mesh.mesh_sp_id != IEEE80211_SYNC_METHOD_VENDOR);
271 msync_dbg("called mesh_sync_vendor_rx_bcn_presp");
272 oui = mesh_get_vendor_oui(sdata);
273 /* here you would implement the vendor offset tracking for this oui */
274}
275
276static void mesh_sync_vendor_adjust_tbtt(struct ieee80211_sub_if_data *sdata)
277{
278 const u8 *oui;
279
280 WARN_ON(sdata->u.mesh.mesh_sp_id != IEEE80211_SYNC_METHOD_VENDOR);
281 msync_dbg("called mesh_sync_vendor_adjust_tbtt");
282 oui = mesh_get_vendor_oui(sdata);
283 /* here you would implement the vendor tsf adjustment for this oui */
284}
285
286/* global variable */
287static struct sync_method sync_methods[] = {
288 {
289 .method = IEEE80211_SYNC_METHOD_NEIGHBOR_OFFSET,
290 .ops = {
291 .rx_bcn_presp = &mesh_sync_offset_rx_bcn_presp,
292 .adjust_tbtt = &mesh_sync_offset_adjust_tbtt,
293 }
294 },
295 {
296 .method = IEEE80211_SYNC_METHOD_VENDOR,
297 .ops = {
298 .rx_bcn_presp = &mesh_sync_vendor_rx_bcn_presp,
299 .adjust_tbtt = &mesh_sync_vendor_adjust_tbtt,
300 }
301 },
302};
303
304struct ieee80211_mesh_sync_ops *ieee80211_mesh_sync_ops_get(u8 method)
305{
306 struct ieee80211_mesh_sync_ops *ops = NULL;
307 u8 i;
308
309 for (i = 0 ; i < ARRAY_SIZE(sync_methods); ++i) {
310 if (sync_methods[i].method == method) {
311 ops = &sync_methods[i].ops;
312 break;
313 }
314 }
315 return ops;
316}