[linux-2.6-block.git] / net / mac80211 / mesh_sync.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;

	/*
	 * Get time when timestamp field was received.  If we don't
	 * have rx timestamps, then use current tsf as an approximation.
	 * drv_get_tsf() must be called before entering the rcu-read
	 * section.
	 */
	if (ieee80211_have_rx_timestamp(rx_status))
		t_r = ieee80211_calculate_rx_timestamp(local, rx_status,
						       24 + 12 +
						       elems->total_len +
						       FCS_LEN,
						       24);
	else
		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;
	}

	/* Timing offset calculation (see 13.13.2.2.2) */
	t_t = le64_to_cpu(mgmt->u.beacon.timestamp);
	sta->mesh->t_offset = t_t - t_r;

	if (test_sta_flag(sta, WLAN_STA_TOFFSET_KNOWN)) {
		s64 t_clockdrift = sta->mesh->t_offset_setpoint - sta->mesh->t_offset;
		msync_dbg(sdata,
			  "STA %pM : t_offset=%lld, t_offset_setpoint=%lld, t_clockdrift=%lld\n",
			  sta->sta.addr, (long long) sta->mesh->t_offset,
			  (long long) sta->mesh->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->mesh->t_offset_setpoint = sta->mesh->t_offset - TOFFSET_SET_MARGIN;
		set_sta_flag(sta, WLAN_STA_TOFFSET_KNOWN);
		msync_dbg(sdata,
			  "STA %pM : offset was invalid, t_offset=%lld\n",
			  sta->sta.addr,
			  (long long) sta->mesh->t_offset);
	}

no_sync:
	rcu_read_unlock();
}

static void mesh_sync_offset_adjust_tbtt(struct ieee80211_sub_if_data *sdata,
					 struct beacon_data *beacon)
{
	struct ieee80211_if_mesh *ifmsh = &sdata->u.mesh;
	u8 cap;

	WARN_ON(ifmsh->mesh_sp_id != IEEE80211_SYNC_METHOD_NEIGHBOR_OFFSET);
	WARN_ON(!rcu_read_lock_held());
	cap = beacon->meshconf->meshconf_cap;

	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);

	beacon->meshconf->meshconf_cap = ifmsh->adjusting_tbtt ?
			IEEE80211_MESHCONF_CAPAB_TBTT_ADJUSTING | cap :
			~IEEE80211_MESHCONF_CAPAB_TBTT_ADJUSTING & cap;
}

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;
}
Commit	Line	Data
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
a802a6eb JC	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 &
bf7cd94d	46	IEEE80211_MESHCONF_CAPAB_TBTT_ADJUSTING) != 0;
dbf498fb JC	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",
bdcbd8e0 JB	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
ce953204 BC	95	/*
	96	* Get time when timestamp field was received. If we don't
	97	* have rx timestamps, then use current tsf as an approximation.
	98	* drv_get_tsf() must be called before entering the rcu-read
	99	* section.
	100	*/
	101	if (ieee80211_have_rx_timestamp(rx_status))
	102	t_r = ieee80211_calculate_rx_timestamp(local, rx_status,
	103	24 + 12 +
	104	elems->total_len +
	105	FCS_LEN,
	106	24);
	107	else
	108	t_r = drv_get_tsf(local, sdata);
dbf498fb JC	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);
bf7cd94d JB	123	msync_dbg(sdata, "STA %pM : is adjusting TBTT\n",
bf7cd94d JB	124	sta->sta.addr);
dbf498fb JC	125	goto no_sync;
	126	}
	127
dbf498fb JC	128	/* Timing offset calculation (see 13.13.2.2.2) */
dbf498fb JC	129	t_t = le64_to_cpu(mgmt->u.beacon.timestamp);
433f5bc1	130	sta->mesh->t_offset = t_t - t_r;
dbf498fb JC	131
dbf498fb JC	132	if (test_sta_flag(sta, WLAN_STA_TOFFSET_KNOWN)) {
433f5bc1	133	s64 t_clockdrift = sta->mesh->t_offset_setpoint - sta->mesh->t_offset;
bdcbd8e0	134	msync_dbg(sdata,
433f5bc1 JB	135	"STA %pM : t_offset=%lld, t_offset_setpoint=%lld, t_clockdrift=%lld\n",
	136	sta->sta.addr, (long long) sta->mesh->t_offset,
	137	(long long) sta->mesh->t_offset_setpoint,
dbf498fb	138	(long long) t_clockdrift);
a802a6eb JC	139
a802a6eb JC	140	if (t_clockdrift > TOFFSET_MAXIMUM_ADJUSTMENT \|\|
bf7cd94d	141	t_clockdrift < -TOFFSET_MAXIMUM_ADJUSTMENT) {
bdcbd8e0 JB	142	msync_dbg(sdata,
bdcbd8e0 JB	143	"STA %pM : t_clockdrift=%lld too large, setpoint reset\n",
a802a6eb JC	144	sta->sta.addr,
	145	(long long) t_clockdrift);
	146	clear_sta_flag(sta, WLAN_STA_TOFFSET_KNOWN);
	147	goto no_sync;
	148	}
	149
dbf498fb	150	spin_lock_bh(&ifmsh->sync_offset_lock);
bf7cd94d JB	151	if (t_clockdrift > ifmsh->sync_offset_clockdrift_max)
bf7cd94d JB	152	ifmsh->sync_offset_clockdrift_max = t_clockdrift;
dbf498fb	153	spin_unlock_bh(&ifmsh->sync_offset_lock);
dbf498fb	154	} else {
433f5bc1	155	sta->mesh->t_offset_setpoint = sta->mesh->t_offset - TOFFSET_SET_MARGIN;
dbf498fb	156	set_sta_flag(sta, WLAN_STA_TOFFSET_KNOWN);
bdcbd8e0	157	msync_dbg(sdata,
433f5bc1	158	"STA %pM : offset was invalid, t_offset=%lld\n",
dbf498fb	159	sta->sta.addr,
433f5bc1	160	(long long) sta->mesh->t_offset);
dbf498fb	161	}
dbf498fb JC	162
	163	no_sync:
	164	rcu_read_unlock();
	165	}
	166
43552be1 TP	167	static void mesh_sync_offset_adjust_tbtt(struct ieee80211_sub_if_data *sdata,
43552be1 TP	168	struct beacon_data *beacon)
dbf498fb JC	169	{
dbf498fb JC	170	struct ieee80211_if_mesh *ifmsh = &sdata->u.mesh;
43552be1	171	u8 cap;
dbf498fb	172
bf7cd94d	173	WARN_ON(ifmsh->mesh_sp_id != IEEE80211_SYNC_METHOD_NEIGHBOR_OFFSET);
8c5bb1fa	174	WARN_ON(!rcu_read_lock_held());
43552be1	175	cap = beacon->meshconf->meshconf_cap;
dbf498fb JC	176
	177	spin_lock_bh(&ifmsh->sync_offset_lock);
	178
bf7cd94d	179	if (ifmsh->sync_offset_clockdrift_max > TOFFSET_MINIMUM_ADJUSTMENT) {
dbf498fb JC	180	/* Since ajusting the tsf here would
	181	* require a possibly blocking call
	182	* to the driver tsf setter, we punt
	183	* the tsf adjustment to the mesh tasklet
	184	*/
bdcbd8e0 JB	185	msync_dbg(sdata,
	186	"TBTT : kicking off TBTT adjustment with clockdrift_max=%lld\n",
	187	ifmsh->sync_offset_clockdrift_max);
bf7cd94d	188	set_bit(MESH_WORK_DRIFT_ADJUST, &ifmsh->wrkq_flags);
37203903 MP	189
37203903 MP	190	ifmsh->adjusting_tbtt = true;
dbf498fb	191	} else {
bdcbd8e0 JB	192	msync_dbg(sdata,
	193	"TBTT : max clockdrift=%lld; too small to adjust\n",
	194	(long long)ifmsh->sync_offset_clockdrift_max);
dbf498fb	195	ifmsh->sync_offset_clockdrift_max = 0;
37203903 MP	196
37203903 MP	197	ifmsh->adjusting_tbtt = false;
dbf498fb JC	198	}
dbf498fb JC	199	spin_unlock_bh(&ifmsh->sync_offset_lock);
43552be1 TP	200
	201	beacon->meshconf->meshconf_cap = ifmsh->adjusting_tbtt ?
	202	IEEE80211_MESHCONF_CAPAB_TBTT_ADJUSTING \| cap :
	203	~IEEE80211_MESHCONF_CAPAB_TBTT_ADJUSTING & cap;
dbf498fb JC	204	}
dbf498fb JC	205
8ba7acf3	206	static const struct sync_method sync_methods[] = {
dbf498fb JC	207	{
	208	.method = IEEE80211_SYNC_METHOD_NEIGHBOR_OFFSET,
	209	.ops = {
	210	.rx_bcn_presp = &mesh_sync_offset_rx_bcn_presp,
	211	.adjust_tbtt = &mesh_sync_offset_adjust_tbtt,
	212	}
	213	},
dbf498fb JC	214	};
dbf498fb JC	215
8ba7acf3	216	const struct ieee80211_mesh_sync_ops *ieee80211_mesh_sync_ops_get(u8 method)
dbf498fb	217	{
bf7cd94d	218	int i;
dbf498fb JC	219
dbf498fb JC	220	for (i = 0 ; i < ARRAY_SIZE(sync_methods); ++i) {
bf7cd94d JB	221	if (sync_methods[i].method == method)
bf7cd94d JB	222	return &sync_methods[i].ops;
dbf498fb	223	}
bf7cd94d	224	return NULL;
dbf498fb	225	}