[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) 2021,2023 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)
 *
 * Returns: If the mesh peer is currently adjusting its TBTT
 */
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.
c00de1c4	6	* Copyright (C) 2021,2023 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)
c00de1c4 BB	40	*
c00de1c4 BB	41	* Returns: If the mesh peer is currently adjusting its TBTT
dbf498fb	42	*/
a5b983c6	43	static bool mesh_peer_tbtt_adjusting(const struct ieee80211_meshconf_ie *cfg)
dbf498fb	44	{
a5b983c6 JB	45	return cfg &&
a5b983c6 JB	46	(cfg->meshconf_cap & IEEE80211_MESHCONF_CAPAB_TBTT_ADJUSTING);
dbf498fb JC	47	}
dbf498fb JC	48
445cd452	49	void mesh_sync_adjust_tsf(struct ieee80211_sub_if_data *sdata)
dbf498fb JC	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) {
445cd452	60	msync_dbg(sdata, "TSF : max clockdrift=%lld; adjusting\n",
bdcbd8e0	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 {
445cd452	65	msync_dbg(sdata, "TSF : max clockdrift=%lld; adjusting by %llu\n",
bdcbd8e0 JB	66	(long long) ifmsh->sync_offset_clockdrift_max,
bdcbd8e0 JB	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	72
354d381b PT	73	if (local->ops->offset_tsf) {
	74	drv_offset_tsf(local, sdata, tsfdelta);
	75	} else {
	76	tsf = drv_get_tsf(local, sdata);
	77	if (tsf != -1ULL)
	78	drv_set_tsf(local, sdata, tsf + tsfdelta);
	79	}
dbf498fb JC	80	}
dbf498fb JC	81
a5b983c6 JB	82	static void
	83	mesh_sync_offset_rx_bcn_presp(struct ieee80211_sub_if_data *sdata, u16 stype,
	84	struct ieee80211_mgmt *mgmt, unsigned int len,
	85	const struct ieee80211_meshconf_ie *mesh_cfg,
	86	struct ieee80211_rx_status *rx_status)
dbf498fb JC	87	{
	88	struct ieee80211_if_mesh *ifmsh = &sdata->u.mesh;
	89	struct ieee80211_local *local = sdata->local;
	90	struct sta_info *sta;
	91	u64 t_t, t_r;
	92
	93	WARN_ON(ifmsh->mesh_sp_id != IEEE80211_SYNC_METHOD_NEIGHBOR_OFFSET);
	94
	95	/* standard mentions only beacons */
	96	if (stype != IEEE80211_STYPE_BEACON)
	97	return;
	98
ce953204 BC	99	/*
	100	* Get time when timestamp field was received. If we don't
	101	* have rx timestamps, then use current tsf as an approximation.
	102	* drv_get_tsf() must be called before entering the rcu-read
	103	* section.
	104	*/
	105	if (ieee80211_have_rx_timestamp(rx_status))
	106	t_r = ieee80211_calculate_rx_timestamp(local, rx_status,
a5b983c6	107	len + FCS_LEN, 24);
ce953204 BC	108	else
ce953204 BC	109	t_r = drv_get_tsf(local, sdata);
dbf498fb JC	110
	111	rcu_read_lock();
	112	sta = sta_info_get(sdata, mgmt->sa);
	113	if (!sta)
	114	goto no_sync;
	115
	116	/* check offset sync conditions (13.13.2.2.1)
	117	*
	118	* TODO also sync to
	119	* dot11MeshNbrOffsetMaxNeighbor non-peer non-MBSS neighbors
	120	*/
	121
a5b983c6	122	if (mesh_peer_tbtt_adjusting(mesh_cfg)) {
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
445cd452	167	static void mesh_sync_offset_adjust_tsf(struct ieee80211_sub_if_data *sdata,
43552be1	168	struct beacon_data *beacon)
dbf498fb JC	169	{
	170	struct ieee80211_if_mesh *ifmsh = &sdata->u.mesh;
	171
bf7cd94d	172	WARN_ON(ifmsh->mesh_sp_id != IEEE80211_SYNC_METHOD_NEIGHBOR_OFFSET);
8c5bb1fa	173	WARN_ON(!rcu_read_lock_held());
dbf498fb JC	174
	175	spin_lock_bh(&ifmsh->sync_offset_lock);
	176
bf7cd94d	177	if (ifmsh->sync_offset_clockdrift_max > TOFFSET_MINIMUM_ADJUSTMENT) {
dbf498fb JC	178	/* Since ajusting the tsf here would
	179	* require a possibly blocking call
	180	* to the driver tsf setter, we punt
	181	* the tsf adjustment to the mesh tasklet
	182	*/
bdcbd8e0	183	msync_dbg(sdata,
445cd452	184	"TSF : kicking off TSF adjustment with clockdrift_max=%lld\n",
bdcbd8e0	185	ifmsh->sync_offset_clockdrift_max);
bf7cd94d	186	set_bit(MESH_WORK_DRIFT_ADJUST, &ifmsh->wrkq_flags);
dbf498fb	187	} else {
bdcbd8e0	188	msync_dbg(sdata,
445cd452	189	"TSF : max clockdrift=%lld; too small to adjust\n",
bdcbd8e0	190	(long long)ifmsh->sync_offset_clockdrift_max);
dbf498fb JC	191	ifmsh->sync_offset_clockdrift_max = 0;
	192	}
	193	spin_unlock_bh(&ifmsh->sync_offset_lock);
	194	}
	195
8ba7acf3	196	static const struct sync_method sync_methods[] = {
dbf498fb JC	197	{
	198	.method = IEEE80211_SYNC_METHOD_NEIGHBOR_OFFSET,
	199	.ops = {
	200	.rx_bcn_presp = &mesh_sync_offset_rx_bcn_presp,
445cd452	201	.adjust_tsf = &mesh_sync_offset_adjust_tsf,
dbf498fb JC	202	}
dbf498fb JC	203	},
dbf498fb JC	204	};
dbf498fb JC	205
8ba7acf3	206	const struct ieee80211_mesh_sync_ops *ieee80211_mesh_sync_ops_get(u8 method)
dbf498fb	207	{
bf7cd94d	208	int i;
dbf498fb JC	209
dbf498fb JC	210	for (i = 0 ; i < ARRAY_SIZE(sync_methods); ++i) {
bf7cd94d JB	211	if (sync_methods[i].method == method)
bf7cd94d JB	212	return &sync_methods[i].ops;
dbf498fb	213	}
bf7cd94d	214	return NULL;
dbf498fb	215	}