drivers/tty/hvc/hvsi_lib.c - arm/linux-arm64-legacy - Git at Google

 #include <linux/types.h>
 #include <linux/init.h>
 #include <linux/delay.h>
 #include <linux/slab.h>
 #include <linux/console.h>
 #include <asm/hvsi.h>

 #include "hvc_console.h"

 static int hvsi_send_packet(struct hvsi_priv *pv, struct hvsi_header *packet)
 {
 	packet->seqno = cpu_to_be16(atomic_inc_return(&pv->seqno));

 	/* Assumes that always succeeds, works in practice */
 	return pv->put_chars(pv->termno, (char *)packet, packet->len);
 }

 static void hvsi_start_handshake(struct hvsi_priv *pv)
 {
 	struct hvsi_query q;

 	/* Reset state */
 	pv->established = 0;
 	atomic_set(&pv->seqno, 0);

 	pr_devel("HVSI@%x: Handshaking started\n", pv->termno);

 	/* Send version query */
 	q.hdr.type = VS_QUERY_PACKET_HEADER;
 	q.hdr.len = sizeof(struct hvsi_query);
 	q.verb = cpu_to_be16(VSV_SEND_VERSION_NUMBER);
 	hvsi_send_packet(pv, &q.hdr);
 }

 static int hvsi_send_close(struct hvsi_priv *pv)
 {
 	struct hvsi_control ctrl;

 	pv->established = 0;

 	ctrl.hdr.type = VS_CONTROL_PACKET_HEADER;
 	ctrl.hdr.len = sizeof(struct hvsi_control);
 	ctrl.verb = cpu_to_be16(VSV_CLOSE_PROTOCOL);
 	return hvsi_send_packet(pv, &ctrl.hdr);
 }

 static void hvsi_cd_change(struct hvsi_priv *pv, int cd)
 {
 	if (cd)
 		pv->mctrl |= TIOCM_CD;
 	else {
 		pv->mctrl &= ~TIOCM_CD;

 		/* We copy the existing hvsi driver semantics
 		 * here which are to trigger a hangup when
 		 * we get a carrier loss.
 		 * Closing our connection to the server will
 		 * do just that.
 		 */
 		if (!pv->is_console && pv->opened) {
 			pr_devel("HVSI@%x Carrier lost, hanging up !\n",
 				 pv->termno);
 			hvsi_send_close(pv);
 		}
 	}
 }

 static void hvsi_got_control(struct hvsi_priv *pv)
 {
 	struct hvsi_control *pkt = (struct hvsi_control *)pv->inbuf;

 	switch (be16_to_cpu(pkt->verb)) {
 	case VSV_CLOSE_PROTOCOL:
 		/* We restart the handshaking */
 		hvsi_start_handshake(pv);
 		break;
 	case VSV_MODEM_CTL_UPDATE:
 		/* Transition of carrier detect */
 		hvsi_cd_change(pv, be32_to_cpu(pkt->word) & HVSI_TSCD);
 		break;
 	}
 }

 static void hvsi_got_query(struct hvsi_priv *pv)
 {
 	struct hvsi_query *pkt = (struct hvsi_query *)pv->inbuf;
 	struct hvsi_query_response r;

 	/* We only handle version queries */
 	if (be16_to_cpu(pkt->verb) != VSV_SEND_VERSION_NUMBER)
 		return;

 	pr_devel("HVSI@%x: Got version query, sending response...\n",
 		 pv->termno);

 	/* Send version response */
 	r.hdr.type = VS_QUERY_RESPONSE_PACKET_HEADER;
 	r.hdr.len = sizeof(struct hvsi_query_response);
 	r.verb = cpu_to_be16(VSV_SEND_VERSION_NUMBER);
 	r.u.version = HVSI_VERSION;
 	r.query_seqno = pkt->hdr.seqno;
 	hvsi_send_packet(pv, &r.hdr);

 	/* Assume protocol is open now */
 	pv->established = 1;
 }

 static void hvsi_got_response(struct hvsi_priv *pv)
 {
 	struct hvsi_query_response *r =
 		(struct hvsi_query_response *)pv->inbuf;

 	switch(r->verb) {
 	case VSV_SEND_MODEM_CTL_STATUS:
 		hvsi_cd_change(pv, be32_to_cpu(r->u.mctrl_word) & HVSI_TSCD);
 		pv->mctrl_update = 1;
 		break;
 	}
 }

 static int hvsi_check_packet(struct hvsi_priv *pv)
 {
 	u8 len, type;

 	/* Check header validity. If it's invalid, we ditch
 	 * the whole buffer and hope we eventually resync
 	 */
 	if (pv->inbuf[0] < 0xfc) {
 		pv->inbuf_len = pv->inbuf_pktlen = 0;
 		return 0;
 	}
 	type = pv->inbuf[0];
 	len = pv->inbuf[1];

 	/* Packet incomplete ? */
 	if (pv->inbuf_len < len)
 		return 0;

 	pr_devel("HVSI@%x: Got packet type %x len %d bytes:\n",
 		 pv->termno, type, len);

 	/* We have a packet, yay ! Handle it */
 	switch(type) {
 	case VS_DATA_PACKET_HEADER:
 		pv->inbuf_pktlen = len - 4;
 		pv->inbuf_cur = 4;
 		return 1;
 	case VS_CONTROL_PACKET_HEADER:
 		hvsi_got_control(pv);
 		break;
 	case VS_QUERY_PACKET_HEADER:
 		hvsi_got_query(pv);
 		break;
 	case VS_QUERY_RESPONSE_PACKET_HEADER:
 		hvsi_got_response(pv);
 		break;
 	}

 	/* Swallow packet and retry */
 	pv->inbuf_len -= len;
 	memmove(pv->inbuf, &pv->inbuf[len], pv->inbuf_len);
 	return 1;
 }

 static int hvsi_get_packet(struct hvsi_priv *pv)
 {
 	/* If we have room in the buffer, ask HV for more */
 	if (pv->inbuf_len < HVSI_INBUF_SIZE)
 		pv->inbuf_len += pv->get_chars(pv->termno,
 					     &pv->inbuf[pv->inbuf_len],
 					     HVSI_INBUF_SIZE - pv->inbuf_len);
 	/*
 	 * If we have at least 4 bytes in the buffer, check for
 	 * a full packet and retry
 	 */
 	if (pv->inbuf_len >= 4)
 		return hvsi_check_packet(pv);
 	return 0;
 }

 int hvsilib_get_chars(struct hvsi_priv *pv, char *buf, int count)
 {
 	unsigned int tries, read = 0;

 	if (WARN_ON(!pv))
 		return -ENXIO;

 	/* If we aren't open, don't do anything in order to avoid races
 	 * with connection establishment. The hvc core will call this
 	 * before we have returned from notifier_add(), and we need to
 	 * avoid multiple users playing with the receive buffer
 	 */
 	if (!pv->opened)
 		return 0;

 	/* We try twice, once with what data we have and once more
 	 * after we try to fetch some more from the hypervisor
 	 */
 	for (tries = 1; count && tries < 2; tries++) {
 		/* Consume existing data packet */
 		if (pv->inbuf_pktlen) {
 			unsigned int l = min(count, (int)pv->inbuf_pktlen);
 			memcpy(&buf[read], &pv->inbuf[pv->inbuf_cur], l);
 			pv->inbuf_cur += l;
 			pv->inbuf_pktlen -= l;
 			count -= l;
 			read += l;
 		}
 		if (count == 0)
 			break;

 		/* Data packet fully consumed, move down remaning data */
 		if (pv->inbuf_cur) {
 			pv->inbuf_len -= pv->inbuf_cur;
 			memmove(pv->inbuf, &pv->inbuf[pv->inbuf_cur],
 				pv->inbuf_len);
 			pv->inbuf_cur = 0;
 		}

 		/* Try to get another packet */
 		if (hvsi_get_packet(pv))
 			tries--;
 	}
 	if (!pv->established) {
 		pr_devel("HVSI@%x: returning -EPIPE\n", pv->termno);
 		return -EPIPE;
 	}
 	return read;
 }

 int hvsilib_put_chars(struct hvsi_priv *pv, const char *buf, int count)
 {
 	struct hvsi_data dp;
 	int rc, adjcount = min(count, HVSI_MAX_OUTGOING_DATA);

 	if (WARN_ON(!pv))
 		return -ENODEV;

 	dp.hdr.type = VS_DATA_PACKET_HEADER;
 	dp.hdr.len = adjcount + sizeof(struct hvsi_header);
 	memcpy(dp.data, buf, adjcount);
 	rc = hvsi_send_packet(pv, &dp.hdr);
 	if (rc <= 0)
 		return rc;
 	return adjcount;
 }

 static void maybe_msleep(unsigned long ms)
 {
 	/* During early boot, IRQs are disabled, use mdelay */
 	if (irqs_disabled())
 		mdelay(ms);
 	else
 		msleep(ms);
 }

 int hvsilib_read_mctrl(struct hvsi_priv *pv)
 {
 	struct hvsi_query q;
 	int rc, timeout;

 	pr_devel("HVSI@%x: Querying modem control status...\n",
 		 pv->termno);

 	pv->mctrl_update = 0;
 	q.hdr.type = VS_QUERY_PACKET_HEADER;
 	q.hdr.len = sizeof(struct hvsi_query);
 	q.verb = cpu_to_be16(VSV_SEND_MODEM_CTL_STATUS);
 	rc = hvsi_send_packet(pv, &q.hdr);
 	if (rc <= 0) {
 		pr_devel("HVSI@%x: Error %d...\n", pv->termno, rc);
 		return rc;
 	}

 	/* Try for up to 200ms */
 	for (timeout = 0; timeout < 20; timeout++) {
 		if (!pv->established)
 			return -ENXIO;
 		if (pv->mctrl_update)
 			return 0;
 		if (!hvsi_get_packet(pv))
 			maybe_msleep(10);
 	}
 	return -EIO;
 }

 int hvsilib_write_mctrl(struct hvsi_priv *pv, int dtr)
 {
 	struct hvsi_control ctrl;
 	unsigned short mctrl;

 	mctrl = pv->mctrl;
 	if (dtr)
 		mctrl |= TIOCM_DTR;
 	else
 		mctrl &= ~TIOCM_DTR;
 	if (mctrl == pv->mctrl)
 		return 0;
 	pv->mctrl = mctrl;

 	pr_devel("HVSI@%x: %s DTR...\n", pv->termno,
 		 dtr ? "Setting" : "Clearing");

 	ctrl.hdr.type = VS_CONTROL_PACKET_HEADER,
 	ctrl.hdr.len = sizeof(struct hvsi_control);
 	ctrl.verb = cpu_to_be16(VSV_SET_MODEM_CTL);
 	ctrl.mask = cpu_to_be32(HVSI_TSDTR);
 	ctrl.word = cpu_to_be32(dtr ? HVSI_TSDTR : 0);
 	return hvsi_send_packet(pv, &ctrl.hdr);
 }

 void hvsilib_establish(struct hvsi_priv *pv)
 {
 	int timeout;

 	pr_devel("HVSI@%x: Establishing...\n", pv->termno);

 	/* Try for up to 200ms, there can be a packet to
 	 * start the process waiting for us...
 	 */
 	for (timeout = 0; timeout < 20; timeout++) {
 		if (pv->established)
 			goto established;
 		if (!hvsi_get_packet(pv))
 			maybe_msleep(10);
 	}

 	/* Failed, send a close connection packet just
 	 * in case
 	 */
 	pr_devel("HVSI@%x:   ... sending close\n", pv->termno);

 	hvsi_send_close(pv);

 	/* Then restart handshake */

 	pr_devel("HVSI@%x:   ... restarting handshake\n", pv->termno);

 	hvsi_start_handshake(pv);

 	pr_devel("HVSI@%x:   ... waiting handshake\n", pv->termno);

 	/* Try for up to 400ms */
 	for (timeout = 0; timeout < 40; timeout++) {
 		if (pv->established)
 			goto established;
 		if (!hvsi_get_packet(pv))
 			maybe_msleep(10);
 	}

 	if (!pv->established) {
 		pr_devel("HVSI@%x: Timeout handshaking, giving up !\n",
 			 pv->termno);
 		return;
 	}
  established:
 	/* Query modem control lines */

 	pr_devel("HVSI@%x:   ... established, reading mctrl\n", pv->termno);

 	hvsilib_read_mctrl(pv);

 	/* Set our own DTR */

 	pr_devel("HVSI@%x:   ... setting mctrl\n", pv->termno);

 	hvsilib_write_mctrl(pv, 1);

 	/* Set the opened flag so reads are allowed */
 	wmb();
 	pv->opened = 1;
 }

 int hvsilib_open(struct hvsi_priv *pv, struct hvc_struct *hp)
 {
 	pr_devel("HVSI@%x: open !\n", pv->termno);

 	/* Keep track of the tty data structure */
 	pv->tty = tty_port_tty_get(&hp->port);

 	hvsilib_establish(pv);

 	return 0;
 }

 void hvsilib_close(struct hvsi_priv *pv, struct hvc_struct *hp)
 {
 	unsigned long flags;

 	pr_devel("HVSI@%x: close !\n", pv->termno);

 	if (!pv->is_console) {
 		pr_devel("HVSI@%x: Not a console, tearing down\n",
 			 pv->termno);

 		/* Clear opened, synchronize with khvcd */
 		spin_lock_irqsave(&hp->lock, flags);
 		pv->opened = 0;
 		spin_unlock_irqrestore(&hp->lock, flags);

 		/* Clear our own DTR */
 		if (!pv->tty || (pv->tty->termios.c_cflag & HUPCL))
 			hvsilib_write_mctrl(pv, 0);

 		/* Tear down the connection */
 		hvsi_send_close(pv);
 	}

 	if (pv->tty)
 		tty_kref_put(pv->tty);
 	pv->tty = NULL;
 }

 void hvsilib_init(struct hvsi_priv *pv,
 		  int (*get_chars)(uint32_t termno, char *buf, int count),
 		  int (*put_chars)(uint32_t termno, const char *buf,
 				   int count),
 		  int termno, int is_console)
 {
 	memset(pv, 0, sizeof(*pv));
 	pv->get_chars = get_chars;
 	pv->put_chars = put_chars;
 	pv->termno = termno;
 	pv->is_console = is_console;
 }
	#include <linux/types.h>
	#include <linux/init.h>
	#include <linux/delay.h>
	#include <linux/slab.h>
	#include <linux/console.h>
	#include <asm/hvsi.h>

	#include "hvc_console.h"

	static int hvsi_send_packet(struct hvsi_priv pv, struct hvsi_header packet)
	{
	packet->seqno = cpu_to_be16(atomic_inc_return(&pv->seqno));

	/* Assumes that always succeeds, works in practice */
	return pv->put_chars(pv->termno, (char *)packet, packet->len);
	}

	static void hvsi_start_handshake(struct hvsi_priv *pv)
	{
	struct hvsi_query q;

	/* Reset state */
	pv->established = 0;
	atomic_set(&pv->seqno, 0);

	pr_devel("HVSI@%x: Handshaking started\n", pv->termno);

	/* Send version query */
	q.hdr.type = VS_QUERY_PACKET_HEADER;
	q.hdr.len = sizeof(struct hvsi_query);
	q.verb = cpu_to_be16(VSV_SEND_VERSION_NUMBER);
	hvsi_send_packet(pv, &q.hdr);
	}

	static int hvsi_send_close(struct hvsi_priv *pv)
	{
	struct hvsi_control ctrl;

	pv->established = 0;

	ctrl.hdr.type = VS_CONTROL_PACKET_HEADER;
	ctrl.hdr.len = sizeof(struct hvsi_control);
	ctrl.verb = cpu_to_be16(VSV_CLOSE_PROTOCOL);
	return hvsi_send_packet(pv, &ctrl.hdr);
	}

	static void hvsi_cd_change(struct hvsi_priv *pv, int cd)
	{
	if (cd)
	pv->mctrl \|= TIOCM_CD;
	else {
	pv->mctrl &= ~TIOCM_CD;

	/* We copy the existing hvsi driver semantics
	* here which are to trigger a hangup when
	* we get a carrier loss.
	* Closing our connection to the server will
	* do just that.
	*/
	if (!pv->is_console && pv->opened) {
	pr_devel("HVSI@%x Carrier lost, hanging up !\n",
	pv->termno);
	hvsi_send_close(pv);
	}
	}
	}

	static void hvsi_got_control(struct hvsi_priv *pv)
	{
	struct hvsi_control pkt = (struct hvsi_control )pv->inbuf;

	switch (be16_to_cpu(pkt->verb)) {
	case VSV_CLOSE_PROTOCOL:
	/* We restart the handshaking */
	hvsi_start_handshake(pv);
	break;
	case VSV_MODEM_CTL_UPDATE:
	/* Transition of carrier detect */
	hvsi_cd_change(pv, be32_to_cpu(pkt->word) & HVSI_TSCD);
	break;
	}
	}

	static void hvsi_got_query(struct hvsi_priv *pv)
	{
	struct hvsi_query pkt = (struct hvsi_query )pv->inbuf;
	struct hvsi_query_response r;

	/* We only handle version queries */
	if (be16_to_cpu(pkt->verb) != VSV_SEND_VERSION_NUMBER)
	return;

	pr_devel("HVSI@%x: Got version query, sending response...\n",
	pv->termno);

	/* Send version response */
	r.hdr.type = VS_QUERY_RESPONSE_PACKET_HEADER;
	r.hdr.len = sizeof(struct hvsi_query_response);
	r.verb = cpu_to_be16(VSV_SEND_VERSION_NUMBER);
	r.u.version = HVSI_VERSION;
	r.query_seqno = pkt->hdr.seqno;
	hvsi_send_packet(pv, &r.hdr);

	/* Assume protocol is open now */
	pv->established = 1;
	}

	static void hvsi_got_response(struct hvsi_priv *pv)
	{
	struct hvsi_query_response *r =
	(struct hvsi_query_response *)pv->inbuf;

	switch(r->verb) {
	case VSV_SEND_MODEM_CTL_STATUS:
	hvsi_cd_change(pv, be32_to_cpu(r->u.mctrl_word) & HVSI_TSCD);
	pv->mctrl_update = 1;
	break;
	}
	}

	static int hvsi_check_packet(struct hvsi_priv *pv)
	{
	u8 len, type;

	/* Check header validity. If it's invalid, we ditch
	* the whole buffer and hope we eventually resync
	*/
	if (pv->inbuf[0] < 0xfc) {
	pv->inbuf_len = pv->inbuf_pktlen = 0;
	return 0;
	}
	type = pv->inbuf[0];
	len = pv->inbuf[1];

	/* Packet incomplete ? */
	if (pv->inbuf_len < len)
	return 0;

	pr_devel("HVSI@%x: Got packet type %x len %d bytes:\n",
	pv->termno, type, len);

	/* We have a packet, yay ! Handle it */
	switch(type) {
	case VS_DATA_PACKET_HEADER:
	pv->inbuf_pktlen = len - 4;
	pv->inbuf_cur = 4;
	return 1;
	case VS_CONTROL_PACKET_HEADER:
	hvsi_got_control(pv);
	break;
	case VS_QUERY_PACKET_HEADER:
	hvsi_got_query(pv);
	break;
	case VS_QUERY_RESPONSE_PACKET_HEADER:
	hvsi_got_response(pv);
	break;
	}

	/* Swallow packet and retry */
	pv->inbuf_len -= len;
	memmove(pv->inbuf, &pv->inbuf[len], pv->inbuf_len);
	return 1;
	}

	static int hvsi_get_packet(struct hvsi_priv *pv)
	{
	/* If we have room in the buffer, ask HV for more */
	if (pv->inbuf_len < HVSI_INBUF_SIZE)
	pv->inbuf_len += pv->get_chars(pv->termno,
	&pv->inbuf[pv->inbuf_len],
	HVSI_INBUF_SIZE - pv->inbuf_len);
	/*
	* If we have at least 4 bytes in the buffer, check for
	* a full packet and retry
	*/
	if (pv->inbuf_len >= 4)
	return hvsi_check_packet(pv);
	return 0;
	}

	int hvsilib_get_chars(struct hvsi_priv pv, char buf, int count)
	{
	unsigned int tries, read = 0;

	if (WARN_ON(!pv))
	return -ENXIO;

	/* If we aren't open, don't do anything in order to avoid races
	* with connection establishment. The hvc core will call this
	* before we have returned from notifier_add(), and we need to
	* avoid multiple users playing with the receive buffer
	*/
	if (!pv->opened)
	return 0;

	/* We try twice, once with what data we have and once more
	* after we try to fetch some more from the hypervisor
	*/
	for (tries = 1; count && tries < 2; tries++) {
	/* Consume existing data packet */
	if (pv->inbuf_pktlen) {
	unsigned int l = min(count, (int)pv->inbuf_pktlen);
	memcpy(&buf[read], &pv->inbuf[pv->inbuf_cur], l);
	pv->inbuf_cur += l;
	pv->inbuf_pktlen -= l;
	count -= l;
	read += l;
	}
	if (count == 0)
	break;

	/* Data packet fully consumed, move down remaning data */
	if (pv->inbuf_cur) {
	pv->inbuf_len -= pv->inbuf_cur;
	memmove(pv->inbuf, &pv->inbuf[pv->inbuf_cur],
	pv->inbuf_len);
	pv->inbuf_cur = 0;
	}

	/* Try to get another packet */
	if (hvsi_get_packet(pv))
	tries--;
	}
	if (!pv->established) {
	pr_devel("HVSI@%x: returning -EPIPE\n", pv->termno);
	return -EPIPE;
	}
	return read;
	}

	int hvsilib_put_chars(struct hvsi_priv pv, const char buf, int count)
	{
	struct hvsi_data dp;
	int rc, adjcount = min(count, HVSI_MAX_OUTGOING_DATA);

	if (WARN_ON(!pv))
	return -ENODEV;

	dp.hdr.type = VS_DATA_PACKET_HEADER;
	dp.hdr.len = adjcount + sizeof(struct hvsi_header);
	memcpy(dp.data, buf, adjcount);
	rc = hvsi_send_packet(pv, &dp.hdr);
	if (rc <= 0)
	return rc;
	return adjcount;
	}

	static void maybe_msleep(unsigned long ms)
	{
	/* During early boot, IRQs are disabled, use mdelay */
	if (irqs_disabled())
	mdelay(ms);
	else
	msleep(ms);
	}

	int hvsilib_read_mctrl(struct hvsi_priv *pv)
	{
	struct hvsi_query q;
	int rc, timeout;

	pr_devel("HVSI@%x: Querying modem control status...\n",
	pv->termno);

	pv->mctrl_update = 0;
	q.hdr.type = VS_QUERY_PACKET_HEADER;
	q.hdr.len = sizeof(struct hvsi_query);
	q.verb = cpu_to_be16(VSV_SEND_MODEM_CTL_STATUS);
	rc = hvsi_send_packet(pv, &q.hdr);
	if (rc <= 0) {
	pr_devel("HVSI@%x: Error %d...\n", pv->termno, rc);
	return rc;
	}

	/* Try for up to 200ms */
	for (timeout = 0; timeout < 20; timeout++) {
	if (!pv->established)
	return -ENXIO;
	if (pv->mctrl_update)
	return 0;
	if (!hvsi_get_packet(pv))
	maybe_msleep(10);
	}
	return -EIO;
	}

	int hvsilib_write_mctrl(struct hvsi_priv *pv, int dtr)
	{
	struct hvsi_control ctrl;
	unsigned short mctrl;

	mctrl = pv->mctrl;
	if (dtr)
	mctrl \|= TIOCM_DTR;
	else
	mctrl &= ~TIOCM_DTR;
	if (mctrl == pv->mctrl)
	return 0;
	pv->mctrl = mctrl;

	pr_devel("HVSI@%x: %s DTR...\n", pv->termno,
	dtr ? "Setting" : "Clearing");

	ctrl.hdr.type = VS_CONTROL_PACKET_HEADER,
	ctrl.hdr.len = sizeof(struct hvsi_control);
	ctrl.verb = cpu_to_be16(VSV_SET_MODEM_CTL);
	ctrl.mask = cpu_to_be32(HVSI_TSDTR);
	ctrl.word = cpu_to_be32(dtr ? HVSI_TSDTR : 0);
	return hvsi_send_packet(pv, &ctrl.hdr);
	}

	void hvsilib_establish(struct hvsi_priv *pv)
	{
	int timeout;

	pr_devel("HVSI@%x: Establishing...\n", pv->termno);

	/* Try for up to 200ms, there can be a packet to
	* start the process waiting for us...
	*/
	for (timeout = 0; timeout < 20; timeout++) {
	if (pv->established)
	goto established;
	if (!hvsi_get_packet(pv))
	maybe_msleep(10);
	}

	/* Failed, send a close connection packet just
	* in case
	*/
	pr_devel("HVSI@%x: ... sending close\n", pv->termno);

	hvsi_send_close(pv);

	/* Then restart handshake */

	pr_devel("HVSI@%x: ... restarting handshake\n", pv->termno);

	hvsi_start_handshake(pv);

	pr_devel("HVSI@%x: ... waiting handshake\n", pv->termno);

	/* Try for up to 400ms */
	for (timeout = 0; timeout < 40; timeout++) {
	if (pv->established)
	goto established;
	if (!hvsi_get_packet(pv))
	maybe_msleep(10);
	}

	if (!pv->established) {
	pr_devel("HVSI@%x: Timeout handshaking, giving up !\n",
	pv->termno);
	return;
	}
	established:
	/* Query modem control lines */

	pr_devel("HVSI@%x: ... established, reading mctrl\n", pv->termno);

	hvsilib_read_mctrl(pv);

	/* Set our own DTR */

	pr_devel("HVSI@%x: ... setting mctrl\n", pv->termno);

	hvsilib_write_mctrl(pv, 1);

	/* Set the opened flag so reads are allowed */
	wmb();
	pv->opened = 1;
	}

	int hvsilib_open(struct hvsi_priv pv, struct hvc_struct hp)
	{
	pr_devel("HVSI@%x: open !\n", pv->termno);

	/* Keep track of the tty data structure */
	pv->tty = tty_port_tty_get(&hp->port);

	hvsilib_establish(pv);

	return 0;
	}

	void hvsilib_close(struct hvsi_priv pv, struct hvc_struct hp)
	{
	unsigned long flags;

	pr_devel("HVSI@%x: close !\n", pv->termno);

	if (!pv->is_console) {
	pr_devel("HVSI@%x: Not a console, tearing down\n",
	pv->termno);

	/* Clear opened, synchronize with khvcd */
	spin_lock_irqsave(&hp->lock, flags);
	pv->opened = 0;
	spin_unlock_irqrestore(&hp->lock, flags);

	/* Clear our own DTR */
	if (!pv->tty \|\| (pv->tty->termios.c_cflag & HUPCL))
	hvsilib_write_mctrl(pv, 0);

	/* Tear down the connection */
	hvsi_send_close(pv);
	}

	if (pv->tty)
	tty_kref_put(pv->tty);
	pv->tty = NULL;
	}

	void hvsilib_init(struct hvsi_priv *pv,
	int (get_chars)(uint32_t termno, char buf, int count),
	int (put_chars)(uint32_t termno, const char buf,
	int count),
	int termno, int is_console)
	{
	memset(pv, 0, sizeof(*pv));
	pv->get_chars = get_chars;
	pv->put_chars = put_chars;
	pv->termno = termno;
	pv->is_console = is_console;
	}