sys/net80211/ieee80211_power.c

/*-
 * Copyright (c) 2002-2008 Sam Leffler, Errno Consulting
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

#include <sys/cdefs.h>
__FBSDID("$FreeBSD: head/sys/net80211/ieee80211_power.c 178354 2008-04-20 20:35:46Z sam $");

/*
 * IEEE 802.11 power save support.
 */
#include "opt_wlan.h"

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/kernel.h>

#include <sys/socket.h>

#include <net/if.h>
#include <net/if_media.h>
#include <net/ethernet.h>

#include <net80211/ieee80211_var.h>

#include <net/bpf.h>

static void ieee80211_update_ps(struct ieee80211vap *, int);
static int ieee80211_set_tim(struct ieee80211_node *, int);

MALLOC_DEFINE(M_80211_POWER, "80211power", "802.11 power save state");

void
ieee80211_power_attach(struct ieee80211com *ic)
{
}

void
ieee80211_power_detach(struct ieee80211com *ic)
{
}

void
ieee80211_power_vattach(struct ieee80211vap *vap)
{
	if (vap->iv_opmode == IEEE80211_M_HOSTAP ||
	    vap->iv_opmode == IEEE80211_M_IBSS) {
		/* NB: driver should override */
		vap->iv_update_ps = ieee80211_update_ps;
		vap->iv_set_tim = ieee80211_set_tim;
	}
}

void
ieee80211_power_latevattach(struct ieee80211vap *vap)
{
	/*
	 * Allocate these only if needed.  Beware that we
	 * know adhoc mode doesn't support ATIM yet...
	 */
	if (vap->iv_opmode == IEEE80211_M_HOSTAP) {
		vap->iv_tim_len = howmany(vap->iv_max_aid,8) * sizeof(uint8_t);
		MALLOC(vap->iv_tim_bitmap, uint8_t *, vap->iv_tim_len,
			M_80211_POWER, M_NOWAIT | M_ZERO);
		if (vap->iv_tim_bitmap == NULL) {
			printf("%s: no memory for TIM bitmap!\n", __func__);
			/* XXX good enough to keep from crashing? */
			vap->iv_tim_len = 0;
		}
	}
}

void
ieee80211_power_vdetach(struct ieee80211vap *vap)
{
	if (vap->iv_tim_bitmap != NULL) {
		FREE(vap->iv_tim_bitmap, M_80211_POWER);
		vap->iv_tim_bitmap = NULL;
	}
}

/*
 * Clear any frames queued on a node's power save queue.
 * The number of frames that were present is returned.
 */
int
ieee80211_node_saveq_drain(struct ieee80211_node *ni)
{
	int qlen;

	IEEE80211_NODE_SAVEQ_LOCK(ni);
	qlen = IEEE80211_NODE_SAVEQ_QLEN(ni);
	_IF_DRAIN(&ni->ni_savedq);
	IEEE80211_NODE_SAVEQ_UNLOCK(ni);

	return qlen;
}

/*
 * Age frames on the power save queue. The aging interval is
 * 4 times the listen interval specified by the station.  This
 * number is factored into the age calculations when the frame
 * is placed on the queue.  We store ages as time differences
 * so we can check and/or adjust only the head of the list.
 * If a frame's age exceeds the threshold then discard it.
 * The number of frames discarded is returned so the caller
 * can check if it needs to adjust the tim.
 */
int
ieee80211_node_saveq_age(struct ieee80211_node *ni)
{
	int discard = 0;

	if (IEEE80211_NODE_SAVEQ_QLEN(ni) != 0) {
#ifdef IEEE80211_DEBUG
		struct ieee80211vap *vap = ni->ni_vap;
#endif
		struct mbuf *m;

		IEEE80211_NODE_SAVEQ_LOCK(ni);
		while (IF_POLL(&ni->ni_savedq, m) != NULL &&
		     M_AGE_GET(m) < IEEE80211_INACT_WAIT) {
			IEEE80211_NOTE(vap, IEEE80211_MSG_POWER, ni,
			     "discard frame, age %u", M_AGE_GET(m));
			_IEEE80211_NODE_SAVEQ_DEQUEUE_HEAD(ni, m);
			m_freem(m);
			discard++;
		}
		if (m != NULL)
			M_AGE_SUB(m, IEEE80211_INACT_WAIT);
		IEEE80211_NODE_SAVEQ_UNLOCK(ni);

		IEEE80211_NOTE(vap, IEEE80211_MSG_POWER, ni,
		    "discard %u frames for age", discard);
		IEEE80211_NODE_STAT_ADD(ni, ps_discard, discard);
	}
	return discard;
}

/*
 * Handle a change in the PS station occupancy.
 */
static void
ieee80211_update_ps(struct ieee80211vap *vap, int nsta)
{

	KASSERT(vap->iv_opmode == IEEE80211_M_HOSTAP ||
		vap->iv_opmode == IEEE80211_M_IBSS,
		("operating mode %u", vap->iv_opmode));
}

/*
 * Indicate whether there are frames queued for a station in power-save mode.
 */
static int
ieee80211_set_tim(struct ieee80211_node *ni, int set)
{
	struct ieee80211vap *vap = ni->ni_vap;
	struct ieee80211com *ic = ni->ni_ic;
	uint16_t aid;
	int changed;

	KASSERT(vap->iv_opmode == IEEE80211_M_HOSTAP ||
		vap->iv_opmode == IEEE80211_M_IBSS,
		("operating mode %u", vap->iv_opmode));

	aid = IEEE80211_AID(ni->ni_associd);
	KASSERT(aid < vap->iv_max_aid,
		("bogus aid %u, max %u", aid, vap->iv_max_aid));

	IEEE80211_LOCK(ic);
	changed = (set != (isset(vap->iv_tim_bitmap, aid) != 0));
	if (changed) {
		if (set) {
			setbit(vap->iv_tim_bitmap, aid);
			vap->iv_ps_pending++;
		} else {
			clrbit(vap->iv_tim_bitmap, aid);
			vap->iv_ps_pending--;
		}
		/* NB: we know vap is in RUN state so no need to check */
		vap->iv_update_beacon(vap, IEEE80211_BEACON_TIM);
	}
	IEEE80211_UNLOCK(ic);

	return changed;
}

/*
 * Save an outbound packet for a node in power-save sleep state.
 * The new packet is placed on the node's saved queue, and the TIM
 * is changed, if necessary.
 */
void
ieee80211_pwrsave(struct ieee80211_node *ni, struct mbuf *m)
{
	struct ieee80211vap *vap = ni->ni_vap;
	struct ieee80211com *ic = ni->ni_ic;
	int qlen, age;

	IEEE80211_NODE_SAVEQ_LOCK(ni);
	if (_IF_QFULL(&ni->ni_savedq)) {
		_IF_DROP(&ni->ni_savedq);
		IEEE80211_NODE_SAVEQ_UNLOCK(ni);
		IEEE80211_NOTE(vap, IEEE80211_MSG_ANY, ni,
		    "pwr save q overflow, drops %d (size %d)",
		    ni->ni_savedq.ifq_drops, IEEE80211_PS_MAX_QUEUE);
#ifdef IEEE80211_DEBUG
		if (ieee80211_msg_dumppkts(vap))
			ieee80211_dump_pkt(ni->ni_ic, mtod(m, caddr_t),
			    m->m_len, -1, -1);
#endif
		m_freem(m);
		return;
	}
	/*
	 * Tag the frame with it's expiry time and insert
	 * it in the queue.  The aging interval is 4 times
	 * the listen interval specified by the station.
	 * Frames that sit around too long are reclaimed
	 * using this information.
	 */
	/* TU -> secs.  XXX handle overflow? */
	age = IEEE80211_TU_TO_MS((ni->ni_intval * ic->ic_bintval) << 2) / 1000;
	_IEEE80211_NODE_SAVEQ_ENQUEUE(ni, m, qlen, age);
	IEEE80211_NODE_SAVEQ_UNLOCK(ni);

	IEEE80211_NOTE(vap, IEEE80211_MSG_POWER, ni,
	    "save frame with age %d, %u now queued", age, qlen);

	if (qlen == 1 && vap->iv_set_tim != NULL)
		vap->iv_set_tim(ni, 1);
}

/*
 * Unload the frames from the ps q but don't send them
 * to the driver yet.  We do this in two stages to minimize
 * locking but also because there's no easy way to preserve
 * ordering given the existing ifnet access mechanisms.
 * XXX could be optimized
 */
static void
pwrsave_flushq(struct ieee80211_node *ni)
{
	struct mbuf *m, *mhead, *mtail;
	int mcount;

	IEEE80211_NODE_SAVEQ_LOCK(ni);
	mcount = IEEE80211_NODE_SAVEQ_QLEN(ni);
	mhead = mtail = NULL;
	for (;;) {
		_IEEE80211_NODE_SAVEQ_DEQUEUE_HEAD(ni, m);
		if (m == NULL)
			break;
		if (mhead == NULL) {
			mhead = m;
			m->m_nextpkt = NULL;
		} else
			mtail->m_nextpkt = m;
		mtail = m;
	}
	IEEE80211_NODE_SAVEQ_UNLOCK(ni);
	if (mhead != NULL) {
		/* XXX need different driver interface */
		/* XXX bypasses q max and OACTIVE */
		struct ifnet *ifp = ni->ni_vap->iv_ifp;
		IF_PREPEND_LIST(&ifp->if_snd, mhead, mtail, mcount);
		if_start(ifp);
	}
}

/*
 * Handle station power-save state change.
 */
void
ieee80211_node_pwrsave(struct ieee80211_node *ni, int enable)
{
	struct ieee80211vap *vap = ni->ni_vap;
	int update;

	update = 0;
	if (enable) {
		if ((ni->ni_flags & IEEE80211_NODE_PWR_MGT) == 0) {
			vap->iv_ps_sta++;
			update = 1;
		}
		ni->ni_flags |= IEEE80211_NODE_PWR_MGT;
		IEEE80211_NOTE(vap, IEEE80211_MSG_POWER, ni,
		    "power save mode on, %u sta's in ps mode", vap->iv_ps_sta);

		if (update)
			vap->iv_update_ps(vap, vap->iv_ps_sta);
	} else {
		if (ni->ni_flags & IEEE80211_NODE_PWR_MGT) {
			vap->iv_ps_sta--;
			update = 1;
		}
		ni->ni_flags &= ~IEEE80211_NODE_PWR_MGT;
		IEEE80211_NOTE(vap, IEEE80211_MSG_POWER, ni,
		    "power save mode off, %u sta's in ps mode", vap->iv_ps_sta);

		/* NB: order here is intentional so TIM is clear before flush */
		if (vap->iv_set_tim != NULL)
			vap->iv_set_tim(ni, 0);
		if (update) {
			/* NB if no sta's in ps, driver should flush mc q */
			vap->iv_update_ps(vap, vap->iv_ps_sta);
		}
		pwrsave_flushq(ni);
	}
}

/*
 * Handle power-save state change in station mode.
 */
void
ieee80211_sta_pwrsave(struct ieee80211vap *vap, int enable)
{
	struct ieee80211_node *ni = vap->iv_bss;
	int qlen;

	if (!((enable != 0) ^ ((ni->ni_flags & IEEE80211_NODE_PWR_MGT) != 0)))
		return;

	IEEE80211_NOTE(vap, IEEE80211_MSG_POWER, ni,
	    "sta power save mode %s", enable ? "on" : "off");
	if (!enable) {
		ni->ni_flags &= ~IEEE80211_NODE_PWR_MGT;
		ieee80211_send_nulldata(ieee80211_ref_node(ni));
		/*
		 * Flush any queued frames; we can do this immediately
		 * because we know they'll be queued behind the null
		 * data frame we send the ap.
		 * XXX can we use a data frame to take us out of ps?
		 */
		qlen = IEEE80211_NODE_SAVEQ_QLEN(ni);
		if (qlen != 0) {
			IEEE80211_NOTE(vap, IEEE80211_MSG_POWER, ni,
			    "flush ps queue, %u packets queued", qlen);
			pwrsave_flushq(ni);
		}
	} else {
		ni->ni_flags |= IEEE80211_NODE_PWR_MGT;
		ieee80211_send_nulldata(ieee80211_ref_node(ni));
	}
}