/*      $NetBSD: nullcons_subr.c,v 1.13 2014/07/25 08:10:35 dholland Exp $      */

/*-
* Copyright (c) 2003 The NetBSD Foundation, 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.
*
* THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
* ``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 THE FOUNDATION OR CONTRIBUTORS
* 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: nullcons_subr.c,v 1.13 2014/07/25 08:10:35 dholland Exp $");

#include <sys/param.h>
#include <sys/proc.h>
#include <sys/systm.h>
#include <sys/buf.h>
#include <sys/ioctl.h>
#include <sys/tty.h>
#include <sys/file.h>
#include <sys/conf.h>
#include <sys/vnode.h>

#include <dev/cons.h>

static struct tty *nulltty;             /* null console tty */

cons_decl(null);

dev_type_read(nullcndev_read);
dev_type_ioctl(nullcndev_ioctl);
dev_type_tty(nullcndev_tty);

static int      nullcons_newdev(struct consdev *);

const struct cdevsw nullcn_devsw = {
       .d_open = nullopen,
       .d_close = nullclose,
       .d_read = nullcndev_read,
       .d_write = nullwrite,
       .d_ioctl = nullcndev_ioctl,
       .d_stop = nullstop,
       .d_tty = nullcndev_tty,
       .d_poll = nopoll,
       .d_mmap = nommap,
       .d_kqfilter = ttykqfilter,
       .d_discard = nodiscard,
       .d_flag = D_TTY
};

/*
* null console device. We need it because of the ioctl() it handles,
* which in particular allows control terminal allocation through
* TIOCSCTTY ioctl. Without the latter, system won't even boot past init(8)
* invocation.
*/
int
nullcndev_read(dev_t dev, struct uio *uio, int flag)
{

       return EIO;
}

int
nullcndev_ioctl(dev_t dev, u_long cmd, void *data, int flag, struct lwp *l)
{
       int error;

       error = (*nulltty->t_linesw->l_ioctl)(nulltty, cmd, data, flag, l);
       if (error != EPASSTHROUGH)
               return error;

       error = ttioctl(nulltty, cmd, data, flag, l);
       if (error != EPASSTHROUGH)
               return error;

       return 0;
}

struct tty*
nullcndev_tty(dev_t dev)
{

       return nulltty;
}

/*
* Mark console as no-op (null) console. Proper initialization is deferred
* to nullconsattach().
*/
void
nullcnprobe(struct consdev *cn)
{

       cn->cn_pri = CN_NULL;
       cn->cn_dev = NODEV;
}

/*
* null console initialization. This includes allocation of a new device and
* a new tty.
*/
void
nullcninit(struct consdev *cn)
{
       static struct consdev nullcn = cons_init(null);

       nullcnprobe(&nullcn);
       cn_tab = &nullcn;
}

/*
* Dumb getc() implementation. Simply blocks on call.
*/
int
nullcngetc(dev_t dev)
{

       for (;;)
               ;
       return 0;
}

/*
* Dumb putc() implementation.
*/
void
nullcnputc(dev_t dev, int c)
{

}

/*
* Allocate a new console device and a tty to handle console ioctls.
*/
int
nullcons_newdev(struct consdev *cn)
{
       int error;
       int bmajor = -1, cmajor = -1;

       if ((cn == NULL) || (cn->cn_pri != CN_NULL) || (cn->cn_dev != NODEV))
               return 0;

       /*
        * Attach no-op device to the device list.
        */
       error = devsw_attach("nullcn", NULL, &bmajor, &nullcn_devsw, &cmajor);
       if (error != 0)
               return error;

       /*
        * Allocate tty (mostly to have sane ioctl()).
        */
       nulltty = tty_alloc();
       nulltty->t_dev = makedev(cmajor, 0);
       tty_attach(nulltty);
       cn->cn_dev = nulltty->t_dev;

       return 0;
}

/*
* Pseudo-device attach function -- it's the right time to do the rest of
* initialization.
*/
void
nullconsattach(int pdev_count)
{

       nullcons_newdev(cn_tab);
}