[linux-block.git] / net / mac80211 / mesh_sync.c

// SPDX-License-Identifier: GPL-2.0-only
/*
 * 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.
 * Copyright (C) 2021 Intel Corporation
 */

#include "ieee80211_i.h"
#include "mesh.h"
#include "driver-ops.h"

/* This is not in the standard.  It represents a tolerable tsf 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 800		/* 0.8 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
 *
 * @cfg: mesh config element from the mesh peer (or %NULL)
 */
static bool mesh_peer_tbtt_adjusting(const struct ieee80211_meshconf_ie *cfg)
{
	return cfg &&
	       (cfg->meshconf_cap & IEEE80211_MESHCONF_CAPAB_TBTT_ADJUSTING);
}

void mesh_sync_adjust_tsf(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, "TSF : 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, "TSF : 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);

	if (local->ops->offset_tsf) {
		drv_offset_tsf(local, sdata, tsfdelta);
	} else {
		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, unsigned int len,
			      const struct ieee80211_meshconf_ie *mesh_cfg,
			      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,
						       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 (mesh_peer_tbtt_adjusting(mesh_cfg)) {
		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_tsf(struct ieee80211_sub_if_data *sdata,
					 struct beacon_data *beacon)
{
	struct ieee80211_if_mesh *ifmsh = &sdata->u.mesh;

	WARN_ON(ifmsh->mesh_sp_id != IEEE80211_SYNC_METHOD_NEIGHBOR_OFFSET);
	WARN_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,
			  "TSF : kicking off TSF adjustment with clockdrift_max=%lld\n",
			  ifmsh->sync_offset_clockdrift_max);
		set_bit(MESH_WORK_DRIFT_ADJUST, &ifmsh->wrkq_flags);
	} else {
		msync_dbg(sdata,
			  "TSF : max clockdrift=%lld; too small to adjust\n",
			  (long long)ifmsh->sync_offset_clockdrift_max);
		ifmsh->sync_offset_clockdrift_max = 0;
	}
	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_tsf = &mesh_sync_offset_adjust_tsf,
		}
	},
};

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
d2912cb1	1	// SPDX-License-Identifier: GPL-2.0-only
dbf498fb JC	2	/*
	3	* Copyright 2011-2012, Pavel Zubarev <pavel.zubarev@gmail.com>
	4	* Copyright 2011-2012, Marco Porsch <marco.porsch@s2005.tu-chemnitz.de>
	5	* Copyright 2011-2012, cozybit Inc.
a5b983c6	6	* Copyright (C) 2021 Intel Corporation
dbf498fb JC	7	*/
	8
	9	#include "ieee80211_i.h"
	10	#include "mesh.h"
	11	#include "driver-ops.h"
	12
445cd452	13	/* This is not in the standard. It represents a tolerable tsf drift below
dbf498fb JC	14	* which we do no TSF adjustment.
dbf498fb JC	15	*/
a802a6eb JC	16	#define TOFFSET_MINIMUM_ADJUSTMENT 10
a802a6eb JC	17
ec14bcd2 JC	18	/* This is not in the standard. It is a margin added to the
	19	* Toffset setpoint to mitigate TSF overcorrection
	20	* introduced by TSF adjustment latency.
	21	*/
	22	#define TOFFSET_SET_MARGIN 20
	23
a802a6eb JC	24	/* This is not in the standard. It represents the maximum Toffset jump above
	25	* which we'll invalidate the Toffset setpoint and choose a new setpoint. This
	26	* could be, for instance, in case a neighbor is restarted and its TSF counter
	27	* reset.
ec14bcd2	28	*/
3a53731d	29	#define TOFFSET_MAXIMUM_ADJUSTMENT 800 /* 0.8 ms */
dbf498fb JC	30
	31	struct sync_method {
	32	u8 method;
	33	struct ieee80211_mesh_sync_ops ops;
	34	};
	35
	36	/**
	37	* mesh_peer_tbtt_adjusting - check if an mp is currently adjusting its TBTT
	38	*
a5b983c6	39	* @cfg: mesh config element from the mesh peer (or %NULL)
dbf498fb	40	*/
a5b983c6	41	static bool mesh_peer_tbtt_adjusting(const struct ieee80211_meshconf_ie *cfg)
dbf498fb	42	{
a5b983c6 JB	43	return cfg &&
a5b983c6 JB	44	(cfg->meshconf_cap & IEEE80211_MESHCONF_CAPAB_TBTT_ADJUSTING);
dbf498fb JC	45	}
dbf498fb JC	46
445cd452	47	void mesh_sync_adjust_tsf(struct ieee80211_sub_if_data *sdata)
dbf498fb JC	48	{
	49	struct ieee80211_local *local = sdata->local;
	50	struct ieee80211_if_mesh *ifmsh = &sdata->u.mesh;
	51	/* sdata->vif.bss_conf.beacon_int in 1024us units, 0.04% */
	52	u64 beacon_int_fraction = sdata->vif.bss_conf.beacon_int * 1024 / 2500;
	53	u64 tsf;
	54	u64 tsfdelta;
	55
	56	spin_lock_bh(&ifmsh->sync_offset_lock);
dbf498fb	57	if (ifmsh->sync_offset_clockdrift_max < beacon_int_fraction) {
445cd452	58	msync_dbg(sdata, "TSF : max clockdrift=%lld; adjusting\n",
bdcbd8e0	59	(long long) ifmsh->sync_offset_clockdrift_max);
dbf498fb JC	60	tsfdelta = -ifmsh->sync_offset_clockdrift_max;
	61	ifmsh->sync_offset_clockdrift_max = 0;
	62	} else {
445cd452	63	msync_dbg(sdata, "TSF : max clockdrift=%lld; adjusting by %llu\n",
bdcbd8e0 JB	64	(long long) ifmsh->sync_offset_clockdrift_max,
bdcbd8e0 JB	65	(unsigned long long) beacon_int_fraction);
dbf498fb JC	66	tsfdelta = -beacon_int_fraction;
	67	ifmsh->sync_offset_clockdrift_max -= beacon_int_fraction;
	68	}
55fabefe	69	spin_unlock_bh(&ifmsh->sync_offset_lock);
dbf498fb	70
354d381b PT	71	if (local->ops->offset_tsf) {
	72	drv_offset_tsf(local, sdata, tsfdelta);
	73	} else {
	74	tsf = drv_get_tsf(local, sdata);
	75	if (tsf != -1ULL)
	76	drv_set_tsf(local, sdata, tsf + tsfdelta);
	77	}
dbf498fb JC	78	}
dbf498fb JC	79
a5b983c6 JB	80	static void
	81	mesh_sync_offset_rx_bcn_presp(struct ieee80211_sub_if_data *sdata, u16 stype,
	82	struct ieee80211_mgmt *mgmt, unsigned int len,
	83	const struct ieee80211_meshconf_ie *mesh_cfg,
	84	struct ieee80211_rx_status *rx_status)
dbf498fb JC	85	{
	86	struct ieee80211_if_mesh *ifmsh = &sdata->u.mesh;
	87	struct ieee80211_local *local = sdata->local;
	88	struct sta_info *sta;
	89	u64 t_t, t_r;
	90
	91	WARN_ON(ifmsh->mesh_sp_id != IEEE80211_SYNC_METHOD_NEIGHBOR_OFFSET);
	92
	93	/* standard mentions only beacons */
	94	if (stype != IEEE80211_STYPE_BEACON)
	95	return;
	96
ce953204 BC	97	/*
	98	* Get time when timestamp field was received. If we don't
	99	* have rx timestamps, then use current tsf as an approximation.
	100	* drv_get_tsf() must be called before entering the rcu-read
	101	* section.
	102	*/
	103	if (ieee80211_have_rx_timestamp(rx_status))
	104	t_r = ieee80211_calculate_rx_timestamp(local, rx_status,
a5b983c6	105	len + FCS_LEN, 24);
ce953204 BC	106	else
ce953204 BC	107	t_r = drv_get_tsf(local, sdata);
dbf498fb JC	108
	109	rcu_read_lock();
	110	sta = sta_info_get(sdata, mgmt->sa);
	111	if (!sta)
	112	goto no_sync;
	113
	114	/* check offset sync conditions (13.13.2.2.1)
	115	*
	116	* TODO also sync to
	117	* dot11MeshNbrOffsetMaxNeighbor non-peer non-MBSS neighbors
	118	*/
	119
a5b983c6	120	if (mesh_peer_tbtt_adjusting(mesh_cfg)) {
bf7cd94d JB	121	msync_dbg(sdata, "STA %pM : is adjusting TBTT\n",
bf7cd94d JB	122	sta->sta.addr);
dbf498fb JC	123	goto no_sync;
	124	}
	125
dbf498fb JC	126	/* Timing offset calculation (see 13.13.2.2.2) */
dbf498fb JC	127	t_t = le64_to_cpu(mgmt->u.beacon.timestamp);
433f5bc1	128	sta->mesh->t_offset = t_t - t_r;
dbf498fb JC	129
dbf498fb JC	130	if (test_sta_flag(sta, WLAN_STA_TOFFSET_KNOWN)) {
433f5bc1	131	s64 t_clockdrift = sta->mesh->t_offset_setpoint - sta->mesh->t_offset;
bdcbd8e0	132	msync_dbg(sdata,
433f5bc1 JB	133	"STA %pM : t_offset=%lld, t_offset_setpoint=%lld, t_clockdrift=%lld\n",
	134	sta->sta.addr, (long long) sta->mesh->t_offset,
	135	(long long) sta->mesh->t_offset_setpoint,
dbf498fb	136	(long long) t_clockdrift);
a802a6eb JC	137
a802a6eb JC	138	if (t_clockdrift > TOFFSET_MAXIMUM_ADJUSTMENT \|\|
bf7cd94d	139	t_clockdrift < -TOFFSET_MAXIMUM_ADJUSTMENT) {
bdcbd8e0 JB	140	msync_dbg(sdata,
bdcbd8e0 JB	141	"STA %pM : t_clockdrift=%lld too large, setpoint reset\n",
a802a6eb JC	142	sta->sta.addr,
	143	(long long) t_clockdrift);
	144	clear_sta_flag(sta, WLAN_STA_TOFFSET_KNOWN);
	145	goto no_sync;
	146	}
	147
dbf498fb	148	spin_lock_bh(&ifmsh->sync_offset_lock);
bf7cd94d JB	149	if (t_clockdrift > ifmsh->sync_offset_clockdrift_max)
bf7cd94d JB	150	ifmsh->sync_offset_clockdrift_max = t_clockdrift;
dbf498fb	151	spin_unlock_bh(&ifmsh->sync_offset_lock);
dbf498fb	152	} else {
433f5bc1	153	sta->mesh->t_offset_setpoint = sta->mesh->t_offset - TOFFSET_SET_MARGIN;
dbf498fb	154	set_sta_flag(sta, WLAN_STA_TOFFSET_KNOWN);
bdcbd8e0	155	msync_dbg(sdata,
433f5bc1	156	"STA %pM : offset was invalid, t_offset=%lld\n",
dbf498fb	157	sta->sta.addr,
433f5bc1	158	(long long) sta->mesh->t_offset);
dbf498fb	159	}
dbf498fb JC	160
	161	no_sync:
	162	rcu_read_unlock();
	163	}
	164
445cd452	165	static void mesh_sync_offset_adjust_tsf(struct ieee80211_sub_if_data *sdata,
43552be1	166	struct beacon_data *beacon)
dbf498fb JC	167	{
	168	struct ieee80211_if_mesh *ifmsh = &sdata->u.mesh;
	169
bf7cd94d	170	WARN_ON(ifmsh->mesh_sp_id != IEEE80211_SYNC_METHOD_NEIGHBOR_OFFSET);
8c5bb1fa	171	WARN_ON(!rcu_read_lock_held());
dbf498fb JC	172
	173	spin_lock_bh(&ifmsh->sync_offset_lock);
	174
bf7cd94d	175	if (ifmsh->sync_offset_clockdrift_max > TOFFSET_MINIMUM_ADJUSTMENT) {
dbf498fb JC	176	/* Since ajusting the tsf here would
	177	* require a possibly blocking call
	178	* to the driver tsf setter, we punt
	179	* the tsf adjustment to the mesh tasklet
	180	*/
bdcbd8e0	181	msync_dbg(sdata,
445cd452	182	"TSF : kicking off TSF adjustment with clockdrift_max=%lld\n",
bdcbd8e0	183	ifmsh->sync_offset_clockdrift_max);
bf7cd94d	184	set_bit(MESH_WORK_DRIFT_ADJUST, &ifmsh->wrkq_flags);
dbf498fb	185	} else {
bdcbd8e0	186	msync_dbg(sdata,
445cd452	187	"TSF : max clockdrift=%lld; too small to adjust\n",
bdcbd8e0	188	(long long)ifmsh->sync_offset_clockdrift_max);
dbf498fb JC	189	ifmsh->sync_offset_clockdrift_max = 0;
	190	}
	191	spin_unlock_bh(&ifmsh->sync_offset_lock);
	192	}
	193
8ba7acf3	194	static const struct sync_method sync_methods[] = {
dbf498fb JC	195	{
	196	.method = IEEE80211_SYNC_METHOD_NEIGHBOR_OFFSET,
	197	.ops = {
	198	.rx_bcn_presp = &mesh_sync_offset_rx_bcn_presp,
445cd452	199	.adjust_tsf = &mesh_sync_offset_adjust_tsf,
dbf498fb JC	200	}
dbf498fb JC	201	},
dbf498fb JC	202	};
dbf498fb JC	203
8ba7acf3	204	const struct ieee80211_mesh_sync_ops *ieee80211_mesh_sync_ops_get(u8 method)
dbf498fb	205	{
bf7cd94d	206	int i;
dbf498fb JC	207
dbf498fb JC	208	for (i = 0 ; i < ARRAY_SIZE(sync_methods); ++i) {
bf7cd94d JB	209	if (sync_methods[i].method == method)
bf7cd94d JB	210	return &sync_methods[i].ops;
dbf498fb	211	}
bf7cd94d	212	return NULL;
dbf498fb	213	}