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/*
* Copyright (C) International Business Machines Corp., 2005
* Author(s): Anthony Liguori <aliguori@us.ibm.com>
*
* Copyright (C) Red Hat 2007
*
* Xen Console
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; under version 2 of the License.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License along
* with this program; if not, see <http://www.gnu.org/licenses/>.
*/

#include <stdlib.h>
#include <errno.h>
#include <string.h>
#include <sys/select.h>
#include <fcntl.h>
#include <unistd.h>
#include <termios.h>
#include <stdarg.h>
#include <sys/mman.h>
#include <xs.h>
#include <xen/io/console.h>
#include <xenctrl.h>

#include "hw.h"
#include "sysemu.h"
#include "qemu-char.h"
#include "xen_backend.h"

struct buffer {
    uint8_t *data;
    size_t consumed;
    size_t size;
    size_t capacity;
    size_t max_capacity;
};

struct XenConsole {
    struct XenDevice xendev; /* must be first */
    struct buffer buffer;
    char console[XEN_BUFSIZE];
    int ring_ref;
    void *sring;
    CharDriverState *chr;
    int backlog;
};

static void buffer_append(struct XenConsole *con)
{
    struct buffer *buffer = &con->buffer;
    XENCONS_RING_IDX cons, prod, size;
    struct xencons_interface *intf = con->sring;

    cons = intf->out_cons;
    prod = intf->out_prod;
    xen_mb();

    size = prod - cons;
    if ((size == 0) || (size > sizeof(intf->out)))
return;

    if ((buffer->capacity - buffer->size) < size) {
buffer->capacity += (size + 1024);
buffer->data = qemu_realloc(buffer->data, buffer->capacity);
    }

    while (cons != prod)
buffer->data[buffer->size++] = intf->out[
MASK_XENCONS_IDX(cons++, intf->out)];

    xen_mb();
    intf->out_cons = cons;
    xen_be_send_notify(&con->xendev);

    if (buffer->max_capacity &&
buffer->size > buffer->max_capacity) {
/* Discard the middle of the data. */

size_t over = buffer->size - buffer->max_capacity;
uint8_t *maxpos = buffer->data + buffer->max_capacity;

memmove(maxpos - over, maxpos, over);
buffer->data = qemu_realloc(buffer->data, buffer->max_capacity);
buffer->size = buffer->capacity = buffer->max_capacity;

if (buffer->consumed > buffer->max_capacity - over)
buffer->consumed = buffer->max_capacity - over;
    }
}

static void buffer_advance(struct buffer *buffer, size_t len)
{
    buffer->consumed += len;
    if (buffer->consumed == buffer->size) {
buffer->consumed = 0;
buffer->size = 0;
    }
}

static int ring_free_bytes(struct XenConsole *con)
{
    struct xencons_interface *intf = con->sring;
    XENCONS_RING_IDX cons, prod, space;

    cons = intf->in_cons;
    prod = intf->in_prod;
    xen_mb();

    space = prod - cons;
    if (space > sizeof(intf->in))
return 0; /* ring is screwed: ignore it */

    return (sizeof(intf->in) - space);
}

static int xencons_can_receive(void *opaque)
{
    struct XenConsole *con = opaque;
    return ring_free_bytes(con);
}

static void xencons_receive(void *opaque, const uint8_t *buf, int len)
{
    struct XenConsole *con = opaque;
    struct xencons_interface *intf = con->sring;
    XENCONS_RING_IDX prod;
    int i, max;

    max = ring_free_bytes(con);
    /* The can_receive() func limits this, but check again anyway */
    if (max < len)
len = max;

    prod = intf->in_prod;
    for (i = 0; i < len; i++) {
intf->in[MASK_XENCONS_IDX(prod++, intf->in)] =
buf[i];
    }
    xen_wmb();
    intf->in_prod = prod;
    xen_be_send_notify(&con->xendev);
}

static void xencons_send(struct XenConsole *con)
{
    ssize_t len, size;

    size = con->buffer.size - con->buffer.consumed;
    if (con->chr)
        len = qemu_chr_write(con->chr, con->buffer.data + con->buffer.consumed,
                             size);
    else
        len = size;
    if (len < 1) {
if (!con->backlog) {
con->backlog = 1;
xen_be_printf(&con->xendev, 1, "backlog piling up, nobody listening?\n");
}
    } else {
buffer_advance(&con->buffer, len);
if (con->backlog && len == size) {
con->backlog = 0;
xen_be_printf(&con->xendev, 1, "backlog is gone\n");
}
    }
}

/* -------------------------------------------------------------------- */

static int con_init(struct XenDevice *xendev)
{
    struct XenConsole *con = container_of(xendev, struct XenConsole, xendev);
    char *type, *dom;

    /* setup */
    dom = xs_get_domain_path(xenstore, con->xendev.dom);
    snprintf(con->console, sizeof(con->console), "%s/console", dom);
    free(dom);

    type = xenstore_read_str(con->console, "type");
    if (!type || strcmp(type, "ioemu") != 0) {
xen_be_printf(xendev, 1, "not for me (type=%s)\n", type);
return -1;
    }

    if (!serial_hds[con->xendev.dev])
xen_be_printf(xendev, 1, "WARNING: serial line %d not configured\n",
                      con->xendev.dev);
    else
        con->chr = serial_hds[con->xendev.dev];

    return 0;
}

static int con_connect(struct XenDevice *xendev)
{
    struct XenConsole *con = container_of(xendev, struct XenConsole, xendev);
    int limit;

    if (xenstore_read_int(con->console, "ring-ref", &con->ring_ref) == -1)
return -1;
    if (xenstore_read_int(con->console, "port", &con->xendev.remote_port) == -1)
return -1;
    if (xenstore_read_int(con->console, "limit", &limit) == 0)
con->buffer.max_capacity = limit;

    con->sring = xc_map_foreign_range(xen_xc, con->xendev.dom,
XC_PAGE_SIZE,
PROT_READ|PROT_WRITE,
con->ring_ref);
    if (!con->sring)
return -1;

    xen_be_bind_evtchn(&con->xendev);
    if (con->chr)
        qemu_chr_add_handlers(con->chr, xencons_can_receive, xencons_receive,
                              NULL, con);

    xen_be_printf(xendev, 1, "ring mfn %d, remote port %d, local port %d, limit %zd\n",
con->ring_ref,
con->xendev.remote_port,
con->xendev.local_port,
con->buffer.max_capacity);
    return 0;
}

static void con_disconnect(struct XenDevice *xendev)
{
    struct XenConsole *con = container_of(xendev, struct XenConsole, xendev);

    if (con->chr)
        qemu_chr_add_handlers(con->chr, NULL, NULL, NULL, NULL);
    xen_be_unbind_evtchn(&con->xendev);

    if (con->sring) {
munmap(con->sring, XC_PAGE_SIZE);
con->sring = NULL;
    }
}

static void con_event(struct XenDevice *xendev)
{
    struct XenConsole *con = container_of(xendev, struct XenConsole, xendev);

    buffer_append(con);
    if (con->buffer.size - con->buffer.consumed)
xencons_send(con);
}

/* -------------------------------------------------------------------- */

struct XenDevOps xen_console_ops = {
    .size = sizeof(struct XenConsole),
    .flags = DEVOPS_FLAG_IGNORE_STATE,
    .init = con_init,
    .connect = con_connect,
    .event = con_event,
    .disconnect = con_disconnect,
};
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