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nullcons_subr.c revision 1.9 
      1 /*	$NetBSD: nullcons_subr.c,v 1.9 2009/04/16 12:57:22 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 1.9 2009/04/16 12:57:22 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 static struct tty *nulltty;		/* null console tty */
     46 
     47 cons_decl(null);
     48 
     49 dev_type_read(nullcndev_read);
     50 dev_type_ioctl(nullcndev_ioctl);
     51 dev_type_tty(nullcndev_tty);
     52 
     53 static int	nullcons_newdev(struct consdev *);
     54 
     55 const struct cdevsw nullcn_devsw = {
     56 	nullopen, nullclose, nullcndev_read, nullwrite, nullcndev_ioctl,
     57 	nullstop, nullcndev_tty, nopoll, nommap, ttykqfilter, D_TTY
     58 };
     59 
     60 /*
     61  * null console device. We need it because of the ioctl() it handles,
     62  * which in particular allows control terminal allocation through
     63  * TIOCSCTTY ioctl. Without the latter, system won't even boot past init(8)
     64  * invocation.
     65  */
     66 int
     67 nullcndev_read(dev_t dev, struct uio *uio, int flag)
     68 {
     69 
     70 	return EIO;
     71 }
     72 
     73 int
     74 nullcndev_ioctl(dev_t dev, u_long cmd, void *data, int flag, struct lwp *l)
     75 {
     76 	int error;
     77 
     78 	error = (*nulltty->t_linesw->l_ioctl)(nulltty, cmd, data, flag, l);
     79 	if (error != EPASSTHROUGH)
     80 		return error;
     81 
     82 	error = ttioctl(nulltty, cmd, data, flag, l);
     83 	if (error != EPASSTHROUGH)
     84 		return error;
     85 
     86 	return 0;
     87 }
     88 
     89 struct tty*
     90 nullcndev_tty(dev_t dev)
     91 {
     92 
     93 	return nulltty;
     94 }
     95 
     96 /*
     97  * Mark console as no-op (null) console. Proper initialization is deferred
     98  * to nullconsattach().
     99  */
    100 void
    101 nullcnprobe(struct consdev *cn)
    102 {
    103 
    104 	cn->cn_pri = CN_NULL;
    105 	cn->cn_dev = NODEV;
    106 }
    107 
    108 /*
    109  * null console initialization. This includes allocation of a new device and
    110  * a new tty.
    111  */
    112 void
    113 nullcninit(struct consdev *cn)
    114 {
    115 	static struct consdev nullcn = cons_init(null);
    116 
    117 	nullcnprobe(&nullcn);
    118 	cn_tab = &nullcn;
    119 }
    120 
    121 /*
    122  * Dumb getc() implementation. Simply blocks on call.
    123  */
    124 int
    125 nullcngetc(dev_t dev)
    126 {
    127 
    128 	for (;;)
    129 		;
    130 	return 0;
    131 }
    132 
    133 /*
    134  * Dumb putc() implementation.
    135  */
    136 void
    137 nullcnputc(dev_t dev, int c)
    138 {
    139 
    140 }
    141 
    142 /*
    143  * Allocate a new console device and a tty to handle console ioctls.
    144  */
    145 int
    146 nullcons_newdev(struct consdev *cn)
    147 {
    148 	int error;
    149 	int bmajor = -1, cmajor = -1;
    150 
    151 	if ((cn == NULL) || (cn->cn_pri != CN_NULL) || (cn->cn_dev != NODEV))
    152 		return 0;
    153 
    154 	/*
    155 	 * Attach no-op device to the device list.
    156 	 */
    157 	error = devsw_attach("nullcn", NULL, &bmajor, &nullcn_devsw, &cmajor);
    158 	if (error != 0)
    159 		return error;
    160 
    161 	/*
    162 	 * Allocate tty (mostly to have sane ioctl()).
    163 	 */
    164 	nulltty = ttymalloc();
    165 	nulltty->t_dev = makedev(cmajor, 0);
    166 	tty_attach(nulltty);
    167 	cn->cn_dev = nulltty->t_dev;
    168 
    169 	return 0;
    170 }
    171 
    172 /*
    173  * Pseudo-device attach function -- it's the right time to do the rest of
    174  * initialization.
    175  */
    176 void
    177 nullconsattach(int pdev_count)
    178 {
    179 
    180 	nullcons_newdev(cn_tab);
    181 }
    182