1 files changed, 424 insertions, 0 deletions
diff --git a/drivers/tty/hvc/hvsi_lib.c b/drivers/tty/hvc/hvsi_lib.c
new file mode 100644
index 000000000..09289c815
--- /dev/null
+++ b/drivers/tty/hvc/hvsi_lib.c
@@ -0,0 +1,424 @@
+// SPDX-License-Identifier: GPL-2.0
+#include <linux/types.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);
+	}
+
+	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;
+}