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nullcons_subr.c revision 1.11.18.1 
      1 /*	$NetBSD: nullcons_subr.c,v 1.11.18.1 2014/05/18 17:45:35 rmind 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 1.11.18.1 2014/05/18 17:45:35 rmind 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 	.d_open = nullopen,
     56 	.d_close = nullclose,
     57 	.d_read = nullcndev_read,
     58 	.d_write = nullwrite,
     59 	.d_ioctl = nullcndev_ioctl,
     60 	.d_stop = nullstop,
     61 	.d_tty = nullcndev_tty,
     62 	.d_poll = nopoll,
     63 	.d_mmap = nommap,
     64 	.d_kqfilter = ttykqfilter,
     65 	.d_flag = D_TTY
     66 };
     67 
     68 /*
     69  * null console device. We need it because of the ioctl() it handles,
     70  * which in particular allows control terminal allocation through
     71  * TIOCSCTTY ioctl. Without the latter, system won't even boot past init(8)
     72  * invocation.
     73  */
     74 int
     75 nullcndev_read(dev_t dev, struct uio *uio, int flag)
     76 {
     77 
     78 	return EIO;
     79 }
     80 
     81 int
     82 nullcndev_ioctl(dev_t dev, u_long cmd, void *data, int flag, struct lwp *l)
     83 {
     84 	int error;
     85 
     86 	error = (*nulltty->t_linesw->l_ioctl)(nulltty, cmd, data, flag, l);
     87 	if (error != EPASSTHROUGH)
     88 		return error;
     89 
     90 	error = ttioctl(nulltty, cmd, data, flag, l);
     91 	if (error != EPASSTHROUGH)
     92 		return error;
     93 
     94 	return 0;
     95 }
     96 
     97 struct tty*
     98 nullcndev_tty(dev_t dev)
     99 {
    100 
    101 	return nulltty;
    102 }
    103 
    104 /*
    105  * Mark console as no-op (null) console. Proper initialization is deferred
    106  * to nullconsattach().
    107  */
    108 void
    109 nullcnprobe(struct consdev *cn)
    110 {
    111 
    112 	cn->cn_pri = CN_NULL;
    113 	cn->cn_dev = NODEV;
    114 }
    115 
    116 /*
    117  * null console initialization. This includes allocation of a new device and
    118  * a new tty.
    119  */
    120 void
    121 nullcninit(struct consdev *cn)
    122 {
    123 	static struct consdev nullcn = cons_init(null);
    124 
    125 	nullcnprobe(&nullcn);
    126 	cn_tab = &nullcn;
    127 }
    128 
    129 /*
    130  * Dumb getc() implementation. Simply blocks on call.
    131  */
    132 int
    133 nullcngetc(dev_t dev)
    134 {
    135 
    136 	for (;;)
    137 		;
    138 	return 0;
    139 }
    140 
    141 /*
    142  * Dumb putc() implementation.
    143  */
    144 void
    145 nullcnputc(dev_t dev, int c)
    146 {
    147 
    148 }
    149 
    150 /*
    151  * Allocate a new console device and a tty to handle console ioctls.
    152  */
    153 int
    154 nullcons_newdev(struct consdev *cn)
    155 {
    156 	int error;
    157 	int bmajor = -1, cmajor = -1;
    158 
    159 	if ((cn == NULL) || (cn->cn_pri != CN_NULL) || (cn->cn_dev != NODEV))
    160 		return 0;
    161 
    162 	/*
    163 	 * Attach no-op device to the device list.
    164 	 */
    165 	error = devsw_attach("nullcn", NULL, &bmajor, &nullcn_devsw, &cmajor);
    166 	if (error != 0)
    167 		return error;
    168 
    169 	/*
    170 	 * Allocate tty (mostly to have sane ioctl()).
    171 	 */
    172 	nulltty = tty_alloc();
    173 	nulltty->t_dev = makedev(cmajor, 0);
    174 	tty_attach(nulltty);
    175 	cn->cn_dev = nulltty->t_dev;
    176 
    177 	return 0;
    178 }
    179 
    180 /*
    181  * Pseudo-device attach function -- it's the right time to do the rest of
    182  * initialization.
    183  */
    184 void
    185 nullconsattach(int pdev_count)
    186 {
    187 
    188 	nullcons_newdev(cn_tab);
    189 }
    190