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nullcons_subr.c revision 1.1 
      1 /*	$NetBSD: nullcons_subr.c,v 1.1 2003/10/17 20:27:38 cdi Exp $	*/
      2 
      3 /*-
      4  * Copyright (c) 2003 The NetBSD Foundation, Inc.
      5  * All rights reserved.
      6  *
      7  * Redistribution and use in source and binary forms, with or without
      8  * modification, are permitted provided that the following conditions
      9  * are met:
     10  * 1. Redistributions of source code must retain the above copyright
     11  *    notice, this list of conditions and the following disclaimer.
     12  * 2. Redistributions in binary form must reproduce the above copyright
     13  *    notice, this list of conditions and the following disclaimer in the
     14  *    documentation and/or other materials provided with the distribution.
     15  * 3. All advertising materials mentioning features or use of this software
     16  *    must display the following acknowledgement:
     17  *        This product includes software developed by the NetBSD
     18  *        Foundation, Inc. and its contributors.
     19  * 4. Neither the name of The NetBSD Foundation nor the names of its
     20  *    contributors may be used to endorse or promote products derived
     21  *    from this software without specific prior written permission.
     22  *
     23  * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
     24  * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
     25  * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
     26  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
     27  * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
     28  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
     29  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
     30  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
     31  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
     32  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
     33  * POSSIBILITY OF SUCH DAMAGE.
     34  */
     35 
     36 #include <sys/cdefs.h>
     37 __KERNEL_RCSID(0, "$NetBSD: nullcons_subr.c,v 1.1 2003/10/17 20:27:38 cdi Exp $");
     38 
     39 #include <sys/param.h>
     40 #include <sys/proc.h>
     41 #include <sys/user.h>
     42 #include <sys/systm.h>
     43 #include <sys/buf.h>
     44 #include <sys/ioctl.h>
     45 #include <sys/tty.h>
     46 #include <sys/file.h>
     47 #include <sys/conf.h>
     48 #include <sys/vnode.h>
     49 
     50 #include <dev/cons.h>
     51 
     52 
     53 extern struct consdev *cn_tab;		/* physical console device info */
     54 
     55 static struct tty *nulltty;		/* null console tty */
     56 
     57 cons_decl(null);
     58 
     59 dev_type_read(nullcndev_read);
     60 dev_type_ioctl(nullcndev_ioctl);
     61 dev_type_tty(nullcndev_tty);
     62 
     63 static int	nullcons_newdev __P((struct consdev *));
     64 
     65 const struct cdevsw nullcn_devsw = {
     66 	nullopen, nullclose, nullcndev_read, nullwrite, nullcndev_ioctl,
     67 	nullstop, nullcndev_tty, nopoll, nommap, ttykqfilter, D_TTY
     68 };
     69 
     70 /*
     71  * null console device. We need it because of the ioctl() it handles,
     72  * which in particular allows control terminal allocation through
     73  * TIOCSCTTY ioctl. Without the latter, system won't even boot past init(8)
     74  * invocation.
     75  */
     76 int
     77 nullcndev_read(dev, uio, flag)
     78 	dev_t dev;
     79 	struct uio *uio;
     80 	int flag;
     81 {
     82 
     83 	for(;;);
     84 	return (0);
     85 }
     86 
     87 int
     88 nullcndev_ioctl(dev, cmd, data, flag, p)
     89 	dev_t dev;
     90 	u_long cmd;
     91 	caddr_t data;
     92 	int flag;
     93 	struct proc *p;
     94 {
     95 	int error;
     96 
     97 	error = (*nulltty->t_linesw->l_ioctl)(nulltty, cmd, data, flag, p);
     98 	if (error != EPASSTHROUGH)
     99 		return (error);
    100 
    101 	error = ttioctl(nulltty, cmd, data, flag, p);
    102 	if (error != EPASSTHROUGH)
    103 		return (error);
    104 
    105 	return (0);
    106 }
    107 
    108 struct tty*
    109 nullcndev_tty(dev)
    110 	dev_t dev;
    111 {
    112 
    113 	return nulltty;
    114 }
    115 
    116 /*
    117  * Mark console as no-op (null) console. Proper initialization is deferred
    118  * to nullconsattach().
    119  */
    120 void
    121 nullcnprobe(cn)
    122 	struct consdev *cn;
    123 {
    124 
    125 	cn->cn_pri = CN_NULL;
    126 	cn->cn_dev = NODEV;
    127 }
    128 
    129 /*
    130  * null console initialization. This includes allocation of a new device and
    131  * a new tty.
    132  */
    133 void
    134 nullcninit(cn)
    135 	struct consdev *cn;
    136 {
    137 	static struct consdev nullcn = cons_init(null);
    138 
    139 	nullcnprobe(&nullcn);
    140 	cn_tab = &nullcn;
    141 }
    142 
    143 /*
    144  * Dumb getc() implementation. Simply blocks on call.
    145  */
    146 int
    147 nullcngetc(dev)
    148 	dev_t dev;
    149 {
    150 
    151 	for(;;);
    152 	return (0);
    153 }
    154 
    155 /*
    156  * Dumb putc() implementation.
    157  */
    158 void
    159 nullcnputc(dev, c)
    160 	dev_t dev;
    161 	int c;
    162 {
    163 
    164 }
    165 
    166 /*
    167  * Allocate a new console device and a tty to handle console ioctls.
    168  */
    169 int
    170 nullcons_newdev(cn)
    171 	struct consdev *cn;
    172 {
    173 	int error;
    174 	int bmajor = -1, cmajor = -1;
    175 
    176 	if ((cn == NULL) || (cn->cn_pri != CN_NULL) || (cn->cn_dev != NODEV))
    177 		return (0);
    178 
    179 	/*
    180 	 * Attach no-op device to the device list.
    181 	 */
    182 	error = devsw_attach("nullcn", NULL, &bmajor, &nullcn_devsw, &cmajor);
    183 	if (error != 0)
    184 		return (error);
    185 
    186 	/*
    187 	 * Allocate tty (mostly to have sane ioctl()).
    188 	 */
    189 	nulltty = ttymalloc();
    190 	nulltty->t_dev = makedev(cmajor, 0);
    191 	tty_attach(nulltty);
    192 	cn->cn_dev = nulltty->t_dev;
    193 
    194 	return (0);
    195 }
    196 
    197 /*
    198  * Pseudo-device attach function -- it's the right time to do the rest of
    199  * initialization.
    200  */
    201 void
    202 nullconsattach(pdev_count)
    203 	int pdev_count;
    204 {
    205 
    206 	nullcons_newdev(cn_tab);
    207 }
    208