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nullcons_subr.c revision 1.10.6.1 
      1 /*	$NetBSD: nullcons_subr.c,v 1.10.6.1 2011/06/06 09:07:39 jruoho 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 1.10.6.1 2011/06/06 09:07:39 jruoho Exp $");
     31 
     32 #include <sys/param.h>
     33 #include <sys/proc.h>
     34 #include <sys/systm.h>
     35 #include <sys/buf.h>
     36 #include <sys/ioctl.h>
     37 #include <sys/tty.h>
     38 #include <sys/file.h>
     39 #include <sys/conf.h>
     40 #include <sys/vnode.h>
     41 
     42 #include <dev/cons.h>
     43 
     44 static struct tty *nulltty;		/* null console tty */
     45 
     46 cons_decl(null);
     47 
     48 dev_type_read(nullcndev_read);
     49 dev_type_ioctl(nullcndev_ioctl);
     50 dev_type_tty(nullcndev_tty);
     51 
     52 static int	nullcons_newdev(struct consdev *);
     53 
     54 const struct cdevsw nullcn_devsw = {
     55 	nullopen, nullclose, nullcndev_read, nullwrite, nullcndev_ioctl,
     56 	nullstop, nullcndev_tty, nopoll, nommap, ttykqfilter, D_TTY
     57 };
     58 
     59 /*
     60  * null console device. We need it because of the ioctl() it handles,
     61  * which in particular allows control terminal allocation through
     62  * TIOCSCTTY ioctl. Without the latter, system won't even boot past init(8)
     63  * invocation.
     64  */
     65 int
     66 nullcndev_read(dev_t dev, struct uio *uio, int flag)
     67 {
     68 
     69 	return EIO;
     70 }
     71 
     72 int
     73 nullcndev_ioctl(dev_t dev, u_long cmd, void *data, int flag, struct lwp *l)
     74 {
     75 	int error;
     76 
     77 	error = (*nulltty->t_linesw->l_ioctl)(nulltty, cmd, data, flag, l);
     78 	if (error != EPASSTHROUGH)
     79 		return error;
     80 
     81 	error = ttioctl(nulltty, cmd, data, flag, l);
     82 	if (error != EPASSTHROUGH)
     83 		return error;
     84 
     85 	return 0;
     86 }
     87 
     88 struct tty*
     89 nullcndev_tty(dev_t dev)
     90 {
     91 
     92 	return nulltty;
     93 }
     94 
     95 /*
     96  * Mark console as no-op (null) console. Proper initialization is deferred
     97  * to nullconsattach().
     98  */
     99 void
    100 nullcnprobe(struct consdev *cn)
    101 {
    102 
    103 	cn->cn_pri = CN_NULL;
    104 	cn->cn_dev = NODEV;
    105 }
    106 
    107 /*
    108  * null console initialization. This includes allocation of a new device and
    109  * a new tty.
    110  */
    111 void
    112 nullcninit(struct consdev *cn)
    113 {
    114 	static struct consdev nullcn = cons_init(null);
    115 
    116 	nullcnprobe(&nullcn);
    117 	cn_tab = &nullcn;
    118 }
    119 
    120 /*
    121  * Dumb getc() implementation. Simply blocks on call.
    122  */
    123 int
    124 nullcngetc(dev_t dev)
    125 {
    126 
    127 	for (;;)
    128 		;
    129 	return 0;
    130 }
    131 
    132 /*
    133  * Dumb putc() implementation.
    134  */
    135 void
    136 nullcnputc(dev_t dev, int c)
    137 {
    138 
    139 }
    140 
    141 /*
    142  * Allocate a new console device and a tty to handle console ioctls.
    143  */
    144 int
    145 nullcons_newdev(struct consdev *cn)
    146 {
    147 	int error;
    148 	int bmajor = -1, cmajor = -1;
    149 
    150 	if ((cn == NULL) || (cn->cn_pri != CN_NULL) || (cn->cn_dev != NODEV))
    151 		return 0;
    152 
    153 	/*
    154 	 * Attach no-op device to the device list.
    155 	 */
    156 	error = devsw_attach("nullcn", NULL, &bmajor, &nullcn_devsw, &cmajor);
    157 	if (error != 0)
    158 		return error;
    159 
    160 	/*
    161 	 * Allocate tty (mostly to have sane ioctl()).
    162 	 */
    163 	nulltty = tty_alloc();
    164 	nulltty->t_dev = makedev(cmajor, 0);
    165 	tty_attach(nulltty);
    166 	cn->cn_dev = nulltty->t_dev;
    167 
    168 	return 0;
    169 }
    170 
    171 /*
    172  * Pseudo-device attach function -- it's the right time to do the rest of
    173  * initialization.
    174  */
    175 void
    176 nullconsattach(int pdev_count)
    177 {
    178 
    179 	nullcons_newdev(cn_tab);
    180 }
    181