sys/dev/nullcons_subr.c

   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/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 = ttymalloc();
 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 }