[mirror_ubuntu-zesty-kernel.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;

	/* 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;
		}

		rcu_read_unlock();

		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);
		rcu_read_unlock();
	}
	return;

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)
{
	const struct ieee80211_mesh_sync_ops *ops = NULL;
	u8 i;

	for (i = 0 ; i < ARRAY_SIZE(sync_methods); ++i) {
		if (sync_methods[i].method == method) {
			ops = &sync_methods[i].ops;
			break;
		}
	}
	return ops;
}
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 &
65821635	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
	95	/* The current tsf is a first approximation for the timestamp
	96	* for the received beacon. Further down we try to get a
	97	* better value from the rx_status->mactime field if
	98	* available. Also we have to call drv_get_tsf() before
	99	* entering the rcu-read section.*/
	100	t_r = drv_get_tsf(local, sdata);
	101
	102	rcu_read_lock();
	103	sta = sta_info_get(sdata, mgmt->sa);
	104	if (!sta)
	105	goto no_sync;
	106
	107	/* check offset sync conditions (13.13.2.2.1)
	108	*
	109	* TODO also sync to
	110	* dot11MeshNbrOffsetMaxNeighbor non-peer non-MBSS neighbors
	111	*/
	112
	113	if (elems->mesh_config && mesh_peer_tbtt_adjusting(elems)) {
	114	clear_sta_flag(sta, WLAN_STA_TOFFSET_KNOWN);
bdcbd8e0	115	msync_dbg(sdata, "STA %pM : is adjusting TBTT\n", sta->sta.addr);
dbf498fb JC	116	goto no_sync;
	117	}
	118
f4bda337 TP	119	if (ieee80211_have_rx_timestamp(rx_status))
	120	/* time when timestamp field was received */
	121	t_r = ieee80211_calculate_rx_timestamp(local, rx_status,
	122	24 + 12 +
	123	elems->total_len +
	124	FCS_LEN,
	125	24);
dbf498fb JC	126
	127	/* Timing offset calculation (see 13.13.2.2.2) */
	128	t_t = le64_to_cpu(mgmt->u.beacon.timestamp);
	129	sta->t_offset = t_t - t_r;
	130
	131	if (test_sta_flag(sta, WLAN_STA_TOFFSET_KNOWN)) {
	132	s64 t_clockdrift = sta->t_offset_setpoint
	133	- sta->t_offset;
bdcbd8e0 JB	134	msync_dbg(sdata,
bdcbd8e0 JB	135	"STA %pM : sta->t_offset=%lld, sta->t_offset_setpoint=%lld, t_clockdrift=%lld\n",
dbf498fb JC	136	sta->sta.addr,
	137	(long long) sta->t_offset,
	138	(long long)
	139	sta->t_offset_setpoint,
	140	(long long) t_clockdrift);
a802a6eb JC	141
	142	if (t_clockdrift > TOFFSET_MAXIMUM_ADJUSTMENT \|\|
	143	t_clockdrift < -TOFFSET_MAXIMUM_ADJUSTMENT) {
bdcbd8e0 JB	144	msync_dbg(sdata,
bdcbd8e0 JB	145	"STA %pM : t_clockdrift=%lld too large, setpoint reset\n",
a802a6eb JC	146	sta->sta.addr,
	147	(long long) t_clockdrift);
	148	clear_sta_flag(sta, WLAN_STA_TOFFSET_KNOWN);
	149	goto no_sync;
	150	}
	151
dbf498fb JC	152	rcu_read_unlock();
	153
	154	spin_lock_bh(&ifmsh->sync_offset_lock);
	155	if (t_clockdrift >
	156	ifmsh->sync_offset_clockdrift_max)
	157	ifmsh->sync_offset_clockdrift_max
	158	= t_clockdrift;
	159	spin_unlock_bh(&ifmsh->sync_offset_lock);
	160
	161	} else {
6ac95b57	162	sta->t_offset_setpoint = sta->t_offset - TOFFSET_SET_MARGIN;
dbf498fb	163	set_sta_flag(sta, WLAN_STA_TOFFSET_KNOWN);
bdcbd8e0 JB	164	msync_dbg(sdata,
bdcbd8e0 JB	165	"STA %pM : offset was invalid, sta->t_offset=%lld\n",
dbf498fb JC	166	sta->sta.addr,
	167	(long long) sta->t_offset);
	168	rcu_read_unlock();
	169	}
	170	return;
	171
	172	no_sync:
	173	rcu_read_unlock();
	174	}
	175
	176	static void mesh_sync_offset_adjust_tbtt(struct ieee80211_sub_if_data *sdata)
	177	{
	178	struct ieee80211_if_mesh *ifmsh = &sdata->u.mesh;
	179
	180	WARN_ON(ifmsh->mesh_sp_id
	181	!= IEEE80211_SYNC_METHOD_NEIGHBOR_OFFSET);
	182	BUG_ON(!rcu_read_lock_held());
	183
	184	spin_lock_bh(&ifmsh->sync_offset_lock);
	185
	186	if (ifmsh->sync_offset_clockdrift_max >
a802a6eb	187	TOFFSET_MINIMUM_ADJUSTMENT) {
dbf498fb JC	188	/* Since ajusting the tsf here would
	189	* require a possibly blocking call
	190	* to the driver tsf setter, we punt
	191	* the tsf adjustment to the mesh tasklet
	192	*/
bdcbd8e0 JB	193	msync_dbg(sdata,
	194	"TBTT : kicking off TBTT adjustment with clockdrift_max=%lld\n",
	195	ifmsh->sync_offset_clockdrift_max);
dbf498fb JC	196	set_bit(MESH_WORK_DRIFT_ADJUST,
dbf498fb JC	197	&ifmsh->wrkq_flags);
37203903 MP	198
37203903 MP	199	ifmsh->adjusting_tbtt = true;
dbf498fb	200	} else {
bdcbd8e0 JB	201	msync_dbg(sdata,
	202	"TBTT : max clockdrift=%lld; too small to adjust\n",
	203	(long long)ifmsh->sync_offset_clockdrift_max);
dbf498fb	204	ifmsh->sync_offset_clockdrift_max = 0;
37203903 MP	205
37203903 MP	206	ifmsh->adjusting_tbtt = false;
dbf498fb JC	207	}
	208	spin_unlock_bh(&ifmsh->sync_offset_lock);
	209	}
	210
8ba7acf3	211	static const struct sync_method sync_methods[] = {
dbf498fb JC	212	{
	213	.method = IEEE80211_SYNC_METHOD_NEIGHBOR_OFFSET,
	214	.ops = {
	215	.rx_bcn_presp = &mesh_sync_offset_rx_bcn_presp,
	216	.adjust_tbtt = &mesh_sync_offset_adjust_tbtt,
	217	}
	218	},
dbf498fb JC	219	};
dbf498fb JC	220
8ba7acf3	221	const struct ieee80211_mesh_sync_ops *ieee80211_mesh_sync_ops_get(u8 method)
dbf498fb	222	{
8ba7acf3	223	const struct ieee80211_mesh_sync_ops *ops = NULL;
dbf498fb JC	224	u8 i;
	225
	226	for (i = 0 ; i < ARRAY_SIZE(sync_methods); ++i) {
	227	if (sync_methods[i].method == method) {
	228	ops = &sync_methods[i].ops;
	229	break;
	230	}
	231	}
	232	return ops;
	233	}