Home | History | Annotate | Line # | Download | only in dev 
      1 /*	$NetBSD: nullcons_subr.c,v 1.13 2014/07/25 08:10:35 dholland 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 1.13 2014/07/25 08:10:35 dholland 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_discard = nodiscard,
     66 	.d_flag = D_TTY
     67 };
     68 
     69 /*
     70  * null console device. We need it because of the ioctl() it handles,
     71  * which in particular allows control terminal allocation through
     72  * TIOCSCTTY ioctl. Without the latter, system won't even boot past init(8)
     73  * invocation.
     74  */
     75 int
     76 nullcndev_read(dev_t dev, struct uio *uio, int flag)
     77 {
     78 
     79 	return EIO;
     80 }
     81 
     82 int
     83 nullcndev_ioctl(dev_t dev, u_long cmd, void *data, int flag, struct lwp *l)
     84 {
     85 	int error;
     86 
     87 	error = (*nulltty->t_linesw->l_ioctl)(nulltty, cmd, data, flag, l);
     88 	if (error != EPASSTHROUGH)
     89 		return error;
     90 
     91 	error = ttioctl(nulltty, cmd, data, flag, l);
     92 	if (error != EPASSTHROUGH)
     93 		return error;
     94 
     95 	return 0;
     96 }
     97 
     98 struct tty*
     99 nullcndev_tty(dev_t dev)
    100 {
    101 
    102 	return nulltty;
    103 }
    104 
    105 /*
    106  * Mark console as no-op (null) console. Proper initialization is deferred
    107  * to nullconsattach().
    108  */
    109 void
    110 nullcnprobe(struct consdev *cn)
    111 {
    112 
    113 	cn->cn_pri = CN_NULL;
    114 	cn->cn_dev = NODEV;
    115 }
    116 
    117 /*
    118  * null console initialization. This includes allocation of a new device and
    119  * a new tty.
    120  */
    121 void
    122 nullcninit(struct consdev *cn)
    123 {
    124 	static struct consdev nullcn = cons_init(null);
    125 
    126 	nullcnprobe(&nullcn);
    127 	cn_tab = &nullcn;
    128 }
    129 
    130 /*
    131  * Dumb getc() implementation. Simply blocks on call.
    132  */
    133 int
    134 nullcngetc(dev_t dev)
    135 {
    136 
    137 	for (;;)
    138 		;
    139 	return 0;
    140 }
    141 
    142 /*
    143  * Dumb putc() implementation.
    144  */
    145 void
    146 nullcnputc(dev_t dev, int c)
    147 {
    148 
    149 }
    150 
    151 /*
    152  * Allocate a new console device and a tty to handle console ioctls.
    153  */
    154 int
    155 nullcons_newdev(struct consdev *cn)
    156 {
    157 	int error;
    158 	int bmajor = -1, cmajor = -1;
    159 
    160 	if ((cn == NULL) || (cn->cn_pri != CN_NULL) || (cn->cn_dev != NODEV))
    161 		return 0;
    162 
    163 	/*
    164 	 * Attach no-op device to the device list.
    165 	 */
    166 	error = devsw_attach("nullcn", NULL, &bmajor, &nullcn_devsw, &cmajor);
    167 	if (error != 0)
    168 		return error;
    169 
    170 	/*
    171 	 * Allocate tty (mostly to have sane ioctl()).
    172 	 */
    173 	nulltty = tty_alloc();
    174 	nulltty->t_dev = makedev(cmajor, 0);
    175 	tty_attach(nulltty);
    176 	cn->cn_dev = nulltty->t_dev;
    177 
    178 	return 0;
    179 }
    180 
    181 /*
    182  * Pseudo-device attach function -- it's the right time to do the rest of
    183  * initialization.
    184  */
    185 void
    186 nullconsattach(int pdev_count)
    187 {
    188 
    189 	nullcons_newdev(cn_tab);
    190 }
    191