219 lines
6.6 KiB
C
219 lines
6.6 KiB
C
/*
|
|
* Copyright 2011-2012, Pavel Zubarev <pavel.zubarev@gmail.com>
|
|
* Copyright 2011-2012, Marco Porsch <marco.porsch@s2005.tu-chemnitz.de>
|
|
* Copyright 2011-2012, cozybit Inc.
|
|
*
|
|
* This program is free software; you can redistribute it and/or modify
|
|
* it under the terms of the GNU General Public License version 2 as
|
|
* published by the Free Software Foundation.
|
|
*/
|
|
|
|
#include "ieee80211_i.h"
|
|
#include "mesh.h"
|
|
#include "driver-ops.h"
|
|
|
|
/* This is not in the standard. It represents a tolerable tbtt drift below
|
|
* which we do no TSF adjustment.
|
|
*/
|
|
#define TOFFSET_MINIMUM_ADJUSTMENT 10
|
|
|
|
/* This is not in the standard. It is a margin added to the
|
|
* Toffset setpoint to mitigate TSF overcorrection
|
|
* introduced by TSF adjustment latency.
|
|
*/
|
|
#define TOFFSET_SET_MARGIN 20
|
|
|
|
/* This is not in the standard. It represents the maximum Toffset jump above
|
|
* which we'll invalidate the Toffset setpoint and choose a new setpoint. This
|
|
* could be, for instance, in case a neighbor is restarted and its TSF counter
|
|
* reset.
|
|
*/
|
|
#define TOFFSET_MAXIMUM_ADJUSTMENT 30000 /* 30 ms */
|
|
|
|
struct sync_method {
|
|
u8 method;
|
|
struct ieee80211_mesh_sync_ops ops;
|
|
};
|
|
|
|
/**
|
|
* mesh_peer_tbtt_adjusting - check if an mp is currently adjusting its TBTT
|
|
*
|
|
* @ie: information elements of a management frame from the mesh peer
|
|
*/
|
|
static bool mesh_peer_tbtt_adjusting(struct ieee802_11_elems *ie)
|
|
{
|
|
return (ie->mesh_config->meshconf_cap &
|
|
IEEE80211_MESHCONF_CAPAB_TBTT_ADJUSTING) != 0;
|
|
}
|
|
|
|
void mesh_sync_adjust_tbtt(struct ieee80211_sub_if_data *sdata)
|
|
{
|
|
struct ieee80211_local *local = sdata->local;
|
|
struct ieee80211_if_mesh *ifmsh = &sdata->u.mesh;
|
|
/* sdata->vif.bss_conf.beacon_int in 1024us units, 0.04% */
|
|
u64 beacon_int_fraction = sdata->vif.bss_conf.beacon_int * 1024 / 2500;
|
|
u64 tsf;
|
|
u64 tsfdelta;
|
|
|
|
spin_lock_bh(&ifmsh->sync_offset_lock);
|
|
if (ifmsh->sync_offset_clockdrift_max < beacon_int_fraction) {
|
|
msync_dbg(sdata, "TBTT : max clockdrift=%lld; adjusting\n",
|
|
(long long) ifmsh->sync_offset_clockdrift_max);
|
|
tsfdelta = -ifmsh->sync_offset_clockdrift_max;
|
|
ifmsh->sync_offset_clockdrift_max = 0;
|
|
} else {
|
|
msync_dbg(sdata, "TBTT : max clockdrift=%lld; adjusting by %llu\n",
|
|
(long long) ifmsh->sync_offset_clockdrift_max,
|
|
(unsigned long long) beacon_int_fraction);
|
|
tsfdelta = -beacon_int_fraction;
|
|
ifmsh->sync_offset_clockdrift_max -= beacon_int_fraction;
|
|
}
|
|
spin_unlock_bh(&ifmsh->sync_offset_lock);
|
|
|
|
tsf = drv_get_tsf(local, sdata);
|
|
if (tsf != -1ULL)
|
|
drv_set_tsf(local, sdata, tsf + tsfdelta);
|
|
}
|
|
|
|
static void mesh_sync_offset_rx_bcn_presp(struct ieee80211_sub_if_data *sdata,
|
|
u16 stype,
|
|
struct ieee80211_mgmt *mgmt,
|
|
struct ieee802_11_elems *elems,
|
|
struct ieee80211_rx_status *rx_status)
|
|
{
|
|
struct ieee80211_if_mesh *ifmsh = &sdata->u.mesh;
|
|
struct ieee80211_local *local = sdata->local;
|
|
struct sta_info *sta;
|
|
u64 t_t, t_r;
|
|
|
|
WARN_ON(ifmsh->mesh_sp_id != IEEE80211_SYNC_METHOD_NEIGHBOR_OFFSET);
|
|
|
|
/* standard mentions only beacons */
|
|
if (stype != IEEE80211_STYPE_BEACON)
|
|
return;
|
|
|
|
/* The current tsf is a first approximation for the timestamp
|
|
* for the received beacon. Further down we try to get a
|
|
* better value from the rx_status->mactime field if
|
|
* available. Also we have to call drv_get_tsf() before
|
|
* entering the rcu-read section.*/
|
|
t_r = drv_get_tsf(local, sdata);
|
|
|
|
rcu_read_lock();
|
|
sta = sta_info_get(sdata, mgmt->sa);
|
|
if (!sta)
|
|
goto no_sync;
|
|
|
|
/* check offset sync conditions (13.13.2.2.1)
|
|
*
|
|
* TODO also sync to
|
|
* dot11MeshNbrOffsetMaxNeighbor non-peer non-MBSS neighbors
|
|
*/
|
|
|
|
if (elems->mesh_config && mesh_peer_tbtt_adjusting(elems)) {
|
|
clear_sta_flag(sta, WLAN_STA_TOFFSET_KNOWN);
|
|
msync_dbg(sdata, "STA %pM : is adjusting TBTT\n",
|
|
sta->sta.addr);
|
|
goto no_sync;
|
|
}
|
|
|
|
if (ieee80211_have_rx_timestamp(rx_status))
|
|
/* time when timestamp field was received */
|
|
t_r = ieee80211_calculate_rx_timestamp(local, rx_status,
|
|
24 + 12 +
|
|
elems->total_len +
|
|
FCS_LEN,
|
|
24);
|
|
|
|
/* Timing offset calculation (see 13.13.2.2.2) */
|
|
t_t = le64_to_cpu(mgmt->u.beacon.timestamp);
|
|
sta->t_offset = t_t - t_r;
|
|
|
|
if (test_sta_flag(sta, WLAN_STA_TOFFSET_KNOWN)) {
|
|
s64 t_clockdrift = sta->t_offset_setpoint - sta->t_offset;
|
|
msync_dbg(sdata,
|
|
"STA %pM : sta->t_offset=%lld, sta->t_offset_setpoint=%lld, t_clockdrift=%lld\n",
|
|
sta->sta.addr, (long long) sta->t_offset,
|
|
(long long) sta->t_offset_setpoint,
|
|
(long long) t_clockdrift);
|
|
|
|
if (t_clockdrift > TOFFSET_MAXIMUM_ADJUSTMENT ||
|
|
t_clockdrift < -TOFFSET_MAXIMUM_ADJUSTMENT) {
|
|
msync_dbg(sdata,
|
|
"STA %pM : t_clockdrift=%lld too large, setpoint reset\n",
|
|
sta->sta.addr,
|
|
(long long) t_clockdrift);
|
|
clear_sta_flag(sta, WLAN_STA_TOFFSET_KNOWN);
|
|
goto no_sync;
|
|
}
|
|
|
|
spin_lock_bh(&ifmsh->sync_offset_lock);
|
|
if (t_clockdrift > ifmsh->sync_offset_clockdrift_max)
|
|
ifmsh->sync_offset_clockdrift_max = t_clockdrift;
|
|
spin_unlock_bh(&ifmsh->sync_offset_lock);
|
|
} else {
|
|
sta->t_offset_setpoint = sta->t_offset - TOFFSET_SET_MARGIN;
|
|
set_sta_flag(sta, WLAN_STA_TOFFSET_KNOWN);
|
|
msync_dbg(sdata,
|
|
"STA %pM : offset was invalid, sta->t_offset=%lld\n",
|
|
sta->sta.addr,
|
|
(long long) sta->t_offset);
|
|
}
|
|
|
|
no_sync:
|
|
rcu_read_unlock();
|
|
}
|
|
|
|
static void mesh_sync_offset_adjust_tbtt(struct ieee80211_sub_if_data *sdata)
|
|
{
|
|
struct ieee80211_if_mesh *ifmsh = &sdata->u.mesh;
|
|
|
|
WARN_ON(ifmsh->mesh_sp_id != IEEE80211_SYNC_METHOD_NEIGHBOR_OFFSET);
|
|
BUG_ON(!rcu_read_lock_held());
|
|
|
|
spin_lock_bh(&ifmsh->sync_offset_lock);
|
|
|
|
if (ifmsh->sync_offset_clockdrift_max > TOFFSET_MINIMUM_ADJUSTMENT) {
|
|
/* Since ajusting the tsf here would
|
|
* require a possibly blocking call
|
|
* to the driver tsf setter, we punt
|
|
* the tsf adjustment to the mesh tasklet
|
|
*/
|
|
msync_dbg(sdata,
|
|
"TBTT : kicking off TBTT adjustment with clockdrift_max=%lld\n",
|
|
ifmsh->sync_offset_clockdrift_max);
|
|
set_bit(MESH_WORK_DRIFT_ADJUST, &ifmsh->wrkq_flags);
|
|
|
|
ifmsh->adjusting_tbtt = true;
|
|
} else {
|
|
msync_dbg(sdata,
|
|
"TBTT : max clockdrift=%lld; too small to adjust\n",
|
|
(long long)ifmsh->sync_offset_clockdrift_max);
|
|
ifmsh->sync_offset_clockdrift_max = 0;
|
|
|
|
ifmsh->adjusting_tbtt = false;
|
|
}
|
|
spin_unlock_bh(&ifmsh->sync_offset_lock);
|
|
}
|
|
|
|
static const struct sync_method sync_methods[] = {
|
|
{
|
|
.method = IEEE80211_SYNC_METHOD_NEIGHBOR_OFFSET,
|
|
.ops = {
|
|
.rx_bcn_presp = &mesh_sync_offset_rx_bcn_presp,
|
|
.adjust_tbtt = &mesh_sync_offset_adjust_tbtt,
|
|
}
|
|
},
|
|
};
|
|
|
|
const struct ieee80211_mesh_sync_ops *ieee80211_mesh_sync_ops_get(u8 method)
|
|
{
|
|
int i;
|
|
|
|
for (i = 0 ; i < ARRAY_SIZE(sync_methods); ++i) {
|
|
if (sync_methods[i].method == method)
|
|
return &sync_methods[i].ops;
|
|
}
|
|
return NULL;
|
|
}
|