// 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, (u8 *)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;
}
ssize_t hvsilib_get_chars(struct hvsi_priv *pv, u8 *buf, size_t count)
{
unsigned int tries;
size_t 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) {
size_t l = min(count, 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;
}
ssize_t hvsilib_put_chars(struct hvsi_priv *pv, const u8 *buf, size_t count)
{
struct hvsi_data dp;
size_t adjcount = min_t(size_t, count, HVSI_MAX_OUTGOING_DATA);
int rc;
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,
ssize_t (*get_chars)(uint32_t termno, u8 *buf, size_t count),
ssize_t (*put_chars)(uint32_t termno, const u8 *buf,
size_t 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;
}
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