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nullcons_subr.c revision 1.5.40.1 
      1 /*	$NetBSD: nullcons_subr.c,v 1.5.40.1 2008/05/16 02:23:49 yamt 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  *
     16  * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
     17  * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
     18  * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
     19  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
     20  * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
     21  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
     22  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
     23  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
     24  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
     25  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
     26  * POSSIBILITY OF SUCH DAMAGE.
     27  */
     28 
     29 #include <sys/cdefs.h>
     30 __KERNEL_RCSID(0, "$NetBSD: nullcons_subr.c,v 1.5.40.1 2008/05/16 02:23:49 yamt Exp $");
     31 
     32 #include <sys/param.h>
     33 #include <sys/proc.h>
     34 #include <sys/user.h>
     35 #include <sys/systm.h>
     36 #include <sys/buf.h>
     37 #include <sys/ioctl.h>
     38 #include <sys/tty.h>
     39 #include <sys/file.h>
     40 #include <sys/conf.h>
     41 #include <sys/vnode.h>
     42 
     43 #include <dev/cons.h>
     44 
     45 
     46 extern struct consdev *cn_tab;		/* physical console device info */
     47 
     48 static struct tty *nulltty;		/* null console tty */
     49 
     50 cons_decl(null);
     51 
     52 dev_type_read(nullcndev_read);
     53 dev_type_ioctl(nullcndev_ioctl);
     54 dev_type_tty(nullcndev_tty);
     55 
     56 static int	nullcons_newdev(struct consdev *);
     57 
     58 const struct cdevsw nullcn_devsw = {
     59 	nullopen, nullclose, nullcndev_read, nullwrite, nullcndev_ioctl,
     60 	nullstop, nullcndev_tty, nopoll, nommap, ttykqfilter, D_TTY
     61 };
     62 
     63 /*
     64  * null console device. We need it because of the ioctl() it handles,
     65  * which in particular allows control terminal allocation through
     66  * TIOCSCTTY ioctl. Without the latter, system won't even boot past init(8)
     67  * invocation.
     68  */
     69 int
     70 nullcndev_read(dev, uio, flag)
     71 	dev_t dev;
     72 	struct uio *uio;
     73 	int flag;
     74 {
     75 
     76 	for(;;);
     77 	return (0);
     78 }
     79 
     80 int
     81 nullcndev_ioctl(dev, cmd, data, flag, l)
     82 	dev_t dev;
     83 	u_long cmd;
     84 	void *data;
     85 	int flag;
     86 	struct lwp *l;
     87 {
     88 	int error;
     89 
     90 	error = (*nulltty->t_linesw->l_ioctl)(nulltty, cmd, data, flag, l);
     91 	if (error != EPASSTHROUGH)
     92 		return (error);
     93 
     94 	error = ttioctl(nulltty, cmd, data, flag, l);
     95 	if (error != EPASSTHROUGH)
     96 		return (error);
     97 
     98 	return (0);
     99 }
    100 
    101 struct tty*
    102 nullcndev_tty(dev)
    103 	dev_t dev;
    104 {
    105 
    106 	return nulltty;
    107 }
    108 
    109 /*
    110  * Mark console as no-op (null) console. Proper initialization is deferred
    111  * to nullconsattach().
    112  */
    113 void
    114 nullcnprobe(cn)
    115 	struct consdev *cn;
    116 {
    117 
    118 	cn->cn_pri = CN_NULL;
    119 	cn->cn_dev = NODEV;
    120 }
    121 
    122 /*
    123  * null console initialization. This includes allocation of a new device and
    124  * a new tty.
    125  */
    126 void
    127 nullcninit(cn)
    128 	struct consdev *cn;
    129 {
    130 	static struct consdev nullcn = cons_init(null);
    131 
    132 	nullcnprobe(&nullcn);
    133 	cn_tab = &nullcn;
    134 }
    135 
    136 /*
    137  * Dumb getc() implementation. Simply blocks on call.
    138  */
    139 int
    140 nullcngetc(dev)
    141 	dev_t dev;
    142 {
    143 
    144 	for(;;);
    145 	return (0);
    146 }
    147 
    148 /*
    149  * Dumb putc() implementation.
    150  */
    151 void
    152 nullcnputc(dev, c)
    153 	dev_t dev;
    154 	int c;
    155 {
    156 
    157 }
    158 
    159 /*
    160  * Allocate a new console device and a tty to handle console ioctls.
    161  */
    162 int
    163 nullcons_newdev(cn)
    164 	struct consdev *cn;
    165 {
    166 	int error;
    167 	int bmajor = -1, cmajor = -1;
    168 
    169 	if ((cn == NULL) || (cn->cn_pri != CN_NULL) || (cn->cn_dev != NODEV))
    170 		return (0);
    171 
    172 	/*
    173 	 * Attach no-op device to the device list.
    174 	 */
    175 	error = devsw_attach("nullcn", NULL, &bmajor, &nullcn_devsw, &cmajor);
    176 	if (error != 0)
    177 		return (error);
    178 
    179 	/*
    180 	 * Allocate tty (mostly to have sane ioctl()).
    181 	 */
    182 	nulltty = ttymalloc();
    183 	nulltty->t_dev = makedev(cmajor, 0);
    184 	tty_attach(nulltty);
    185 	cn->cn_dev = nulltty->t_dev;
    186 
    187 	return (0);
    188 }
    189 
    190 /*
    191  * Pseudo-device attach function -- it's the right time to do the rest of
    192  * initialization.
    193  */
    194 void
    195 nullconsattach(pdev_count)
    196 	int pdev_count;
    197 {
    198 
    199 	nullcons_newdev(cn_tab);
    200 }
    201