Home | History | Annotate | Line # | Download | only in dev
nullcons_subr.c revision 1.7 
      1 /*	$NetBSD: nullcons_subr.c,v 1.7 2009/02/28 00:40:47 tsutsui 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 1.7 2009/02/28 00:40:47 tsutsui 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 	return EIO;
     77 }
     78 
     79 int
     80 nullcndev_ioctl(dev, cmd, data, flag, l)
     81 	dev_t dev;
     82 	u_long cmd;
     83 	void *data;
     84 	int flag;
     85 	struct lwp *l;
     86 {
     87 	int error;
     88 
     89 	error = (*nulltty->t_linesw->l_ioctl)(nulltty, cmd, data, flag, l);
     90 	if (error != EPASSTHROUGH)
     91 		return (error);
     92 
     93 	error = ttioctl(nulltty, cmd, data, flag, l);
     94 	if (error != EPASSTHROUGH)
     95 		return (error);
     96 
     97 	return (0);
     98 }
     99 
    100 struct tty*
    101 nullcndev_tty(dev)
    102 	dev_t dev;
    103 {
    104 
    105 	return nulltty;
    106 }
    107 
    108 /*
    109  * Mark console as no-op (null) console. Proper initialization is deferred
    110  * to nullconsattach().
    111  */
    112 void
    113 nullcnprobe(cn)
    114 	struct consdev *cn;
    115 {
    116 
    117 	cn->cn_pri = CN_NULL;
    118 	cn->cn_dev = NODEV;
    119 }
    120 
    121 /*
    122  * null console initialization. This includes allocation of a new device and
    123  * a new tty.
    124  */
    125 void
    126 nullcninit(cn)
    127 	struct consdev *cn;
    128 {
    129 	static struct consdev nullcn = cons_init(null);
    130 
    131 	nullcnprobe(&nullcn);
    132 	cn_tab = &nullcn;
    133 }
    134 
    135 /*
    136  * Dumb getc() implementation. Simply blocks on call.
    137  */
    138 int
    139 nullcngetc(dev)
    140 	dev_t dev;
    141 {
    142 
    143 	for(;;);
    144 	return (0);
    145 }
    146 
    147 /*
    148  * Dumb putc() implementation.
    149  */
    150 void
    151 nullcnputc(dev, c)
    152 	dev_t dev;
    153 	int c;
    154 {
    155 
    156 }
    157 
    158 /*
    159  * Allocate a new console device and a tty to handle console ioctls.
    160  */
    161 int
    162 nullcons_newdev(cn)
    163 	struct consdev *cn;
    164 {
    165 	int error;
    166 	int bmajor = -1, cmajor = -1;
    167 
    168 	if ((cn == NULL) || (cn->cn_pri != CN_NULL) || (cn->cn_dev != NODEV))
    169 		return (0);
    170 
    171 	/*
    172 	 * Attach no-op device to the device list.
    173 	 */
    174 	error = devsw_attach("nullcn", NULL, &bmajor, &nullcn_devsw, &cmajor);
    175 	if (error != 0)
    176 		return (error);
    177 
    178 	/*
    179 	 * Allocate tty (mostly to have sane ioctl()).
    180 	 */
    181 	nulltty = ttymalloc();
    182 	nulltty->t_dev = makedev(cmajor, 0);
    183 	tty_attach(nulltty);
    184 	cn->cn_dev = nulltty->t_dev;
    185 
    186 	return (0);
    187 }
    188 
    189 /*
    190  * Pseudo-device attach function -- it's the right time to do the rest of
    191  * initialization.
    192  */
    193 void
    194 nullconsattach(pdev_count)
    195 	int pdev_count;
    196 {
    197 
    198 	nullcons_newdev(cn_tab);
    199 }
    200