xref: /src/sys/netbt/hci_link.c

/*	$NetBSD: hci_link.c,v 1.8 2006/11/16 01:33:45 christos Exp $	*/

/*-
 * Copyright (c) 2005 Iain Hibbert.
 * Copyright (c) 2006 Itronix Inc.
 * 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.
 * 3. The name of Itronix Inc. may not be used to endorse
 *    or promote products derived from this software without specific
 *    prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY ITRONIX INC. ``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 ITRONIX INC. 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>
__KERNEL_RCSID(0, "$NetBSD: hci_link.c,v 1.8 2006/11/16 01:33:45 christos Exp $");

#include <sys/param.h>
#include <sys/kernel.h>
#include <sys/malloc.h>
#include <sys/mbuf.h>
#include <sys/proc.h>
#include <sys/queue.h>
#include <sys/systm.h>

#include <netbt/bluetooth.h>
#include <netbt/hci.h>
#include <netbt/l2cap.h>
#include <netbt/sco.h>

/*******************************************************************************
 *
 *	HCI ACL Connections
 */

/*
 * Automatically expire unused ACL connections after this number of
 * seconds (if zero, do not expire unused connections) [sysctl]
 */
int hci_acl_expiry = 10;	/* seconds */

/*
 * hci_acl_open(unit, bdaddr)
 *
 * open ACL connection to remote bdaddr. Only one ACL connection is permitted
 * between any two Bluetooth devices, so we look for an existing one before
 * trying to start a new one.
 */
struct hci_link *
hci_acl_open(struct hci_unit *unit, bdaddr_t *bdaddr)
{
	struct hci_link *link;
	struct hci_memo *memo;
	hci_create_con_cp cp;
	int err;

	KASSERT(unit);
	KASSERT(bdaddr);

	link = hci_link_lookup_bdaddr(unit, bdaddr, HCI_LINK_ACL);
	if (link == NULL) {
		link = hci_link_alloc(unit);
		if (link == NULL)
			return NULL;

		link->hl_type = HCI_LINK_ACL;
		bdaddr_copy(&link->hl_bdaddr, bdaddr);
	}

	switch(link->hl_state) {
	case HCI_LINK_CLOSED:
		/*
		 * open connection to remote device
		 */
		memset(&cp, 0, sizeof(cp));
		bdaddr_copy(&cp.bdaddr, bdaddr);
		cp.pkt_type = htole16(unit->hci_packet_type);

		memo = hci_memo_find(unit, bdaddr);
		if (memo != NULL) {
			cp.page_scan_rep_mode = memo->response.page_scan_rep_mode;
			cp.page_scan_mode = memo->response.page_scan_mode;
			cp.clock_offset = htole16(memo->response.clock_offset);
		}

		if (unit->hci_link_policy & HCI_LINK_POLICY_ENABLE_ROLE_SWITCH)
			cp.accept_role_switch = 1;

		err = hci_send_cmd(unit, HCI_CMD_CREATE_CON, &cp, sizeof(cp));
		if (err) {
			hci_link_free(link, err);
			return NULL;
		}

		link->hl_state = HCI_LINK_WAIT_CONNECT;
		break;

	case HCI_LINK_WAIT_CONNECT:
		/*
		 * somebody else already trying to connect, we just
		 * sit on the bench with them..
		 */
		break;

	case HCI_LINK_OPEN:
		/*
		 * If already open, halt any expiry timeouts. We dont need
		 * to care about already invoking timeouts since refcnt >0
		 * will keep the link alive.
		 */
		callout_stop(&link->hl_expire);
		break;

	default:
		UNKNOWN(link->hl_state);
		return NULL;
	}

	/* open */
	link->hl_refcnt++;

	return link;
}

/*
 * Close ACL connection. When there are no more references to this link,
 * we can either close it down or schedule a delayed closedown.
 */
void
hci_acl_close(struct hci_link *link, int err)
{

	KASSERT(link);

	if (--link->hl_refcnt == 0) {
		if (link->hl_state == HCI_LINK_CLOSED)
			hci_link_free(link, err);
		else if (hci_acl_expiry > 0)
			callout_schedule(&link->hl_expire, hci_acl_expiry * hz);
	}
}

/*
 * Incoming ACL connection.
 *
 * For now, we accept all connections but it would be better to check
 * the L2CAP listen list and only accept when there is a listener
 * available.
 *
 * There should not be a link to the same bdaddr already, we check
 * anyway though its left unhandled for now.
 */
struct hci_link *
hci_acl_newconn(struct hci_unit *unit, bdaddr_t *bdaddr)
{
	struct hci_link *link;

	link = hci_link_lookup_bdaddr(unit, bdaddr, HCI_LINK_ACL);
	if (link != NULL)
		return NULL;

	link = hci_link_alloc(unit);
	if (link != NULL) {
		link->hl_state = HCI_LINK_WAIT_CONNECT;
		link->hl_type = HCI_LINK_ACL;
		bdaddr_copy(&link->hl_bdaddr, bdaddr);

		if (hci_acl_expiry > 0)
			callout_schedule(&link->hl_expire, hci_acl_expiry * hz);
	}

	return link;
}

void
hci_acl_timeout(void *arg)
{
	struct hci_link *link = arg;
	hci_discon_cp cp;
	int s, err;

	s = splsoftnet();
	callout_ack(&link->hl_expire);

	if (link->hl_refcnt > 0)
		goto out;

	DPRINTF("link #%d expired\n", link->hl_handle);

	switch (link->hl_state) {
	case HCI_LINK_CLOSED:
	case HCI_LINK_WAIT_CONNECT:
		hci_link_free(link, ECONNRESET);
		break;

	case HCI_LINK_OPEN:
		cp.con_handle = htole16(link->hl_handle);
		cp.reason = 0x13; /* "Remote User Terminated Connection" */

		err = hci_send_cmd(link->hl_unit, HCI_CMD_DISCONNECT,
					&cp, sizeof(cp));

		if (err) {
			DPRINTF("error %d sending HCI_CMD_DISCONNECT\n",
			    err);
		}

		break;

	default:
		UNKNOWN(link->hl_state);
		break;
	}

out:
	splx(s);
}

/*
 * Receive ACL Data
 *
 * we accumulate packet fragments on the hci_link structure
 * until a full L2CAP frame is ready, then send it on.
 */
void
hci_acl_recv(struct mbuf *m, struct hci_unit *unit)
{
	struct hci_link *link;
	hci_acldata_hdr_t hdr;
	uint16_t handle, want;
	int pb, got;

	KASSERT(m);
	KASSERT(unit);

	KASSERT(m->m_pkthdr.len >= sizeof(hdr));
	m_copydata(m, 0, sizeof(hdr), &hdr);
	m_adj(m, sizeof(hdr));

#ifdef DIAGNOSTIC
	if (hdr.type != HCI_ACL_DATA_PKT) {
		printf("%s: bad ACL packet type\n", unit->hci_devname);
		goto bad;
	}

	if (m->m_pkthdr.len != le16toh(hdr.length)) {
		printf("%s: bad ACL packet length (%d != %d)\n",
			unit->hci_devname, m->m_pkthdr.len, le16toh(hdr.length));
		goto bad;
	}
#endif

	hdr.length = le16toh(hdr.length);
	hdr.con_handle = le16toh(hdr.con_handle);
	handle = HCI_CON_HANDLE(hdr.con_handle);
	pb = HCI_PB_FLAG(hdr.con_handle);

	link = hci_link_lookup_handle(unit, handle);
	if (link == NULL) {
		hci_discon_cp cp;

		DPRINTF("%s: dumping packet for unknown handle #%d\n",
			unit->hci_devname, handle);

		/*
		 * There is no way to find out what this connection handle is
		 * for, just get rid of it. This may happen, if a USB dongle
		 * is plugged into a self powered hub and does not reset when
		 * the system is shut down.
		 */
		cp.con_handle = htole16(handle);
		cp.reason = 0x13; /* "Remote User Terminated Connection" */
		hci_send_cmd(unit, HCI_CMD_DISCONNECT, &cp, sizeof(cp));
		goto bad;
	}

	switch (pb) {
	case HCI_PACKET_START:
		if (link->hl_rxp != NULL)
			printf("%s: dropped incomplete ACL packet\n",
				unit->hci_devname);

		if (m->m_pkthdr.len < sizeof(l2cap_hdr_t)) {
			printf("%s: short ACL packet\n",
				unit->hci_devname);

			goto bad;
		}

		link->hl_rxp = m;
		got = m->m_pkthdr.len;
		break;

	case HCI_PACKET_FRAGMENT:
		if (link->hl_rxp == NULL) {
			printf("%s: unexpected packet fragment\n",
				unit->hci_devname);

			goto bad;
		}

		got = m->m_pkthdr.len + link->hl_rxp->m_pkthdr.len;
		m_cat(link->hl_rxp, m);
		m = link->hl_rxp;
		m->m_pkthdr.len = got;
		break;

	default:
		printf("%s: unknown packet type\n",
			unit->hci_devname);

		goto bad;
	}

	m_copydata(m, 0, sizeof(want), &want);
	want = le16toh(want) + sizeof(l2cap_hdr_t) - got;

	if (want > 0)
		return;

	link->hl_rxp = NULL;

	if (want == 0) {
		l2cap_recv_frame(m, link);
		return;
	}

bad:
	m_freem(m);
}

/*
 * Send ACL data on link
 *
 * We must fragment packets into chunks of less than unit->hci_max_acl_size and
 * prepend a relevant ACL header to each fragment. We keep a PDU structure
 * attached to the link, so that completed fragments can be marked off and
 * more data requested from above once the PDU is sent.
 */
int
hci_acl_send(struct mbuf *m, struct hci_link *link,
		struct l2cap_channel *chan)
{
	struct l2cap_pdu *pdu;
	struct mbuf *n = NULL;
	int plen, mlen, num = 0;

	KASSERT(link);
	KASSERT(m);
	KASSERT(m->m_flags & M_PKTHDR);
	KASSERT(m->m_pkthdr.len > 0);

	if (link->hl_state == HCI_LINK_CLOSED) {
		m_freem(m);
		return ENETDOWN;
	}

	pdu = pool_get(&l2cap_pdu_pool, PR_NOWAIT);
	if (pdu == NULL)
		goto nomem;

	pdu->lp_chan = chan;
	pdu->lp_pending = 0;
	MBUFQ_INIT(&pdu->lp_data);

	plen = m->m_pkthdr.len;
	mlen = link->hl_unit->hci_max_acl_size;

	DPRINTFN(5, "%s: handle #%d, plen = %d, max = %d\n",
		link->hl_unit->hci_devname, link->hl_handle, plen, mlen);

	while (plen > 0) {
		if (plen > mlen) {
			n = m_split(m, mlen, M_DONTWAIT);
			if (n == NULL)
				goto nomem;
		} else {
			mlen = plen;
		}

		if (num++ == 0)
			m->m_flags |= M_PROTO1;	/* tag first fragment */

		DPRINTFN(10, "chunk of %d (plen = %d) bytes\n", mlen, plen);
		MBUFQ_ENQUEUE(&pdu->lp_data, m);
		m = n;
		plen -= mlen;
	}

	TAILQ_INSERT_TAIL(&link->hl_txq, pdu, lp_next);
	link->hl_txqlen += num;

	hci_acl_start(link);

	return 0;

nomem:
	if (m) m_freem(m);
	if (n) m_freem(n);
	if (pdu) {
		MBUFQ_DRAIN(&pdu->lp_data);
		pool_put(&l2cap_pdu_pool, pdu);
	}

	return ENOMEM;
}

/*
 * Start sending ACL data on link.
 *
 *	We may use all the available packet slots. The reason that we add
 * the ACL encapsulation here rather than in hci_acl_send() is that L2CAP
 * signal packets may be queued before the handle is given to us..
 *
 * this is called from hci_acl_send() above, and the event processing
 * code (for CON_COMPL and NUM_COMPL_PKTS)
 */
void
hci_acl_start(struct hci_link *link)
{
	struct hci_unit *unit;
	hci_acldata_hdr_t *hdr;
	struct l2cap_pdu *pdu;
	struct mbuf *m;
	uint16_t handle;

	KASSERT(link);

	unit = link->hl_unit;
	KASSERT(unit);

	/* this is mainly to block ourselves (below) */
	if (link->hl_state != HCI_LINK_OPEN)
		return;

	if (link->hl_txqlen == 0 || unit->hci_num_acl_pkts == 0)
		return;

	/* find first PDU with data to send */
	pdu = TAILQ_FIRST(&link->hl_txq);
	for (;;) {
		if (pdu == NULL)
			return;

		if (MBUFQ_FIRST(&pdu->lp_data) != NULL)
			break;

		pdu = TAILQ_NEXT(pdu, lp_next);
	}

	while (unit->hci_num_acl_pkts > 0) {
		MBUFQ_DEQUEUE(&pdu->lp_data, m);
		KASSERT(m != NULL);

		if (m->m_flags & M_PROTO1)
			handle = HCI_MK_CON_HANDLE(link->hl_handle,
						HCI_PACKET_START, 0);
		else
			handle = HCI_MK_CON_HANDLE(link->hl_handle,
						HCI_PACKET_FRAGMENT, 0);

		M_PREPEND(m, sizeof(*hdr), M_DONTWAIT);
		if (m == NULL)
			break;

		hdr = mtod(m, hci_acldata_hdr_t *);
		hdr->type = HCI_ACL_DATA_PKT;
		hdr->con_handle = htole16(handle);
		hdr->length = htole16(m->m_pkthdr.len - sizeof(*hdr));

		link->hl_txqlen--;
		pdu->lp_pending++;

		hci_output_acl(unit, m);

		if (MBUFQ_FIRST(&pdu->lp_data) == NULL) {
			if (pdu->lp_chan) {
				/*
				 * This should enable streaming of PDUs - when
				 * we have placed all the fragments on the acl
				 * output queue, we trigger the L2CAP layer to
				 * send us down one more. Use a false state so
				 * we dont run into ourselves coming back from
				 * the future..
				 */
				link->hl_state = HCI_LINK_BLOCK;
				l2cap_start(pdu->lp_chan);
				link->hl_state = HCI_LINK_OPEN;
			}

			pdu = TAILQ_NEXT(pdu, lp_next);
			if (pdu == NULL)
				break;
		}
	}

	/*
	 * We had our turn now, move to the back of the queue to let
	 * other links have a go at the output buffers..
	 */
	if (TAILQ_NEXT(link, hl_next)) {
		TAILQ_REMOVE(&unit->hci_links, link, hl_next);
		TAILQ_INSERT_TAIL(&unit->hci_links, link, hl_next);
	}
}

/*
 * Confirm ACL packets cleared from Controller buffers. We scan our PDU
 * list to clear pending fragments and signal upstream for more data
 * when a PDU is complete.
 */
void
hci_acl_complete(struct hci_link *link, int num)
{
	struct l2cap_pdu *pdu;
	struct l2cap_channel *chan;

	DPRINTFN(5, "handle #%d (%d)\n", link->hl_handle, num);

	while (num > 0) {
		pdu = TAILQ_FIRST(&link->hl_txq);
		if (pdu == NULL) {
			printf("%s: %d packets completed on handle #%x "
				"but none pending!\n",
				link->hl_unit->hci_devname, num,
				link->hl_handle);
			return;
		}

		if (num >= pdu->lp_pending) {
			num -= pdu->lp_pending;
			pdu->lp_pending = 0;

			if (MBUFQ_FIRST(&pdu->lp_data) == NULL) {
				TAILQ_REMOVE(&link->hl_txq, pdu, lp_next);
				chan = pdu->lp_chan;
				if (chan != NULL) {
					chan->lc_pending--;
					(*chan->lc_proto->complete)
							(chan->lc_upper, 1);

					if (chan->lc_pending == 0)
						l2cap_start(chan);
				}

				pool_put(&l2cap_pdu_pool, pdu);
			}
		} else {
			pdu->lp_pending -= num;
			num = 0;
		}
	}
}

/*******************************************************************************
 *
 *	HCI SCO Connections
 */

/*
 * Incoming SCO Connection. We check the list for anybody willing
 * to take it.
 */
struct hci_link *
hci_sco_newconn(struct hci_unit *unit, bdaddr_t *bdaddr)
{
	struct sockaddr_bt laddr, raddr;
	struct sco_pcb *pcb, *new;
	struct hci_link *sco, *acl;

	memset(&laddr, 0, sizeof(laddr));
	laddr.bt_len = sizeof(laddr);
	laddr.bt_family = AF_BLUETOOTH;
	bdaddr_copy(&laddr.bt_bdaddr, &unit->hci_bdaddr);

	memset(&raddr, 0, sizeof(raddr));
	raddr.bt_len = sizeof(raddr);
	raddr.bt_family = AF_BLUETOOTH;
	bdaddr_copy(&raddr.bt_bdaddr, bdaddr);

	/*
	 * There should already be an ACL link up and running before
	 * the controller sends us SCO connection requests, but you
	 * never know..
	 */
	acl = hci_link_lookup_bdaddr(unit, bdaddr, HCI_LINK_ACL);
	if (acl == NULL || acl->hl_state != HCI_LINK_OPEN)
		return NULL;

	LIST_FOREACH(pcb, &sco_pcb, sp_next) {
		if ((pcb->sp_flags & SP_LISTENING) == 0)
			continue;

		new = (*pcb->sp_proto->newconn)(pcb->sp_upper, &laddr, &raddr);
		if (new == NULL)
			continue;

		/*
		 * Ok, got new pcb so we can start a new link and fill
		 * in all the details.
		 */
		bdaddr_copy(&new->sp_laddr, &unit->hci_bdaddr);
		bdaddr_copy(&new->sp_raddr, bdaddr);

		sco = hci_link_alloc(unit);
		if (sco == NULL) {
			sco_detach(&new);
			return NULL;
		}

		sco->hl_type = HCI_LINK_SCO;
		bdaddr_copy(&sco->hl_bdaddr, bdaddr);

		sco->hl_link = hci_acl_open(unit, bdaddr);
		KASSERT(sco->hl_link == acl);

		sco->hl_sco = new;
		new->sp_link = sco;

		new->sp_mtu = unit->hci_max_sco_size;
		return sco;
	}

	return NULL;
}

/*
 * receive SCO packet, we only need to strip the header and send
 * it to the right handler
 */
void
hci_sco_recv(struct mbuf *m, struct hci_unit *unit)
{
	struct hci_link *link;
	hci_scodata_hdr_t hdr;
	uint16_t handle;

	KASSERT(m);
	KASSERT(unit);

	KASSERT(m->m_pkthdr.len >= sizeof(hdr));
	m_copydata(m, 0, sizeof(hdr), &hdr);
	m_adj(m, sizeof(hdr));

#ifdef DIAGNOSTIC
	if (hdr.type != HCI_SCO_DATA_PKT) {
		printf("%s: bad SCO packet type\n", unit->hci_devname);
		goto bad;
	}

	if (m->m_pkthdr.len != hdr.length) {
		printf("%s: bad SCO packet length (%d != %d)\n", unit->hci_devname, m->m_pkthdr.len, hdr.length);
		goto bad;
	}
#endif

	hdr.con_handle = le16toh(hdr.con_handle);
	handle = HCI_CON_HANDLE(hdr.con_handle);

	link = hci_link_lookup_handle(unit, handle);
	if (link == NULL || link->hl_type == HCI_LINK_ACL) {
		DPRINTF("%s: dumping packet for unknown handle #%d\n",
			unit->hci_devname, handle);

		goto bad;
	}

	(*link->hl_sco->sp_proto->input)(link->hl_sco->sp_upper, m);
	return;

bad:
	m_freem(m);
}

void
hci_sco_start(struct hci_link *link)
{
}

/*
 * SCO packets have completed at the controller, so we can
 * signal up to free the buffer space.
 */
void
hci_sco_complete(struct hci_link *link, int num)
{

	DPRINTFN(5, "handle #%d (num=%d)\n", link->hl_handle, num);
	link->hl_sco->sp_pending--;
	(*link->hl_sco->sp_proto->complete)(link->hl_sco->sp_upper, num);
}

/*******************************************************************************
 *
 *	Generic HCI Connection alloc/free/lookup etc
 */

struct hci_link *
hci_link_alloc(struct hci_unit *unit)
{
	struct hci_link *link;

	KASSERT(unit);

	link = malloc(sizeof(struct hci_link), M_BLUETOOTH, M_NOWAIT | M_ZERO);
	if (link == NULL)
		return NULL;

	link->hl_unit = unit;
	link->hl_state = HCI_LINK_CLOSED;

	/* init ACL portion */
	callout_init(&link->hl_expire);
	callout_setfunc(&link->hl_expire, hci_acl_timeout, link);

	TAILQ_INIT(&link->hl_txq);	/* outgoing packets */
	TAILQ_INIT(&link->hl_reqs);	/* request queue */

	link->hl_mtu = L2CAP_MTU_DEFAULT;		/* L2CAP signal mtu */
	link->hl_flush = L2CAP_FLUSH_TIMO_DEFAULT;	/* flush timeout */

	/* init SCO portion */
	MBUFQ_INIT(&link->hl_data);

	/* attach to unit */
	TAILQ_INSERT_HEAD(&unit->hci_links, link, hl_next);
	return link;
}

void
hci_link_free(struct hci_link *link, int err)
{
	struct l2cap_req *req;
	struct l2cap_pdu *pdu;
	struct l2cap_channel *chan, *next;

	KASSERT(link);

	DPRINTF("#%d, type = %d, state = %d, refcnt = %d\n",
		link->hl_handle, link->hl_type,
		link->hl_state, link->hl_refcnt);

	/* ACL reference count */
	if (link->hl_refcnt > 0) {
		next = LIST_FIRST(&l2cap_active_list);
		while ((chan = next) != NULL) {
			next = LIST_NEXT(chan, lc_ncid);
			if (chan->lc_link == link)
				l2cap_close(chan, err);
		}
	}
	KASSERT(link->hl_refcnt == 0);

	/* ACL L2CAP requests.. */
	while ((req = TAILQ_FIRST(&link->hl_reqs)) != NULL)
		l2cap_request_free(req);

	KASSERT(TAILQ_EMPTY(&link->hl_reqs));

	/* ACL outgoing data queue */
	while ((pdu = TAILQ_FIRST(&link->hl_txq)) != NULL) {
		TAILQ_REMOVE(&link->hl_txq, pdu, lp_next);
		MBUFQ_DRAIN(&pdu->lp_data);
		if (pdu->lp_pending)
			link->hl_unit->hci_num_acl_pkts += pdu->lp_pending;

		pool_put(&l2cap_pdu_pool, pdu);
	}

	KASSERT(TAILQ_EMPTY(&link->hl_txq));

	/* ACL incoming data packet */
	if (link->hl_rxp != NULL) {
		m_freem(link->hl_rxp);
		link->hl_rxp = NULL;
	}

	/* SCO master ACL link */
	if (link->hl_link != NULL) {
		hci_acl_close(link->hl_link, err);
		link->hl_link = NULL;
	}

	/* SCO pcb */
	if (link->hl_sco != NULL) {
		struct sco_pcb *pcb;

		pcb = link->hl_sco;
		pcb->sp_link = NULL;
		link->hl_sco = NULL;
		(*pcb->sp_proto->disconnected)(pcb->sp_upper, err);
	}

	/* flush any SCO data */
	MBUFQ_DRAIN(&link->hl_data);

	/*
	 * Halt the callout - if its already running we cannot free the
	 * link structure but the timeout function will call us back in
	 * any case.
	 */
	link->hl_state = HCI_LINK_CLOSED;
	callout_stop(&link->hl_expire);
	if (callout_invoking(&link->hl_expire))
		return;

	TAILQ_REMOVE(&link->hl_unit->hci_links, link, hl_next);
	free(link, M_BLUETOOTH);
}

/*
 * Lookup HCI link by address and type. Note that for SCO links there may
 * be more than one link per address, so we only return links with no
 * handle (ie new links)
 */
struct hci_link *
hci_link_lookup_bdaddr(struct hci_unit *unit, bdaddr_t *bdaddr, uint16_t type)
{
	struct hci_link *link;

	KASSERT(unit);
	KASSERT(bdaddr);

	TAILQ_FOREACH(link, &unit->hci_links, hl_next) {
		if (link->hl_type != type)
			continue;

		if (type == HCI_LINK_SCO && link->hl_handle != 0)
			continue;

		if (bdaddr_same(&link->hl_bdaddr, bdaddr))
			break;
	}

	return link;
}

struct hci_link *
hci_link_lookup_handle(struct hci_unit *unit, uint16_t handle)
{
	struct hci_link *link;

	KASSERT(unit);

	TAILQ_FOREACH(link, &unit->hci_links, hl_next) {
		if (handle == link->hl_handle)
			break;
	}

	return link;
}