The Design and Implementation of the FreeBSD Operating System, Second Edition
Now available: The Design and Implementation of the FreeBSD Operating System (Second Edition)


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FreeBSD/Linux Kernel Cross Reference
sys/dev/nullcons_subr.c

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    1 /*      $NetBSD: nullcons_subr.c,v 1.4 2005/12/11 12:20:53 christos 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  * 3. All advertising materials mentioning features or use of this software
   16  *    must display the following acknowledgement:
   17  *        This product includes software developed by the NetBSD
   18  *        Foundation, Inc. and its contributors.
   19  * 4. Neither the name of The NetBSD Foundation nor the names of its
   20  *    contributors may be used to endorse or promote products derived
   21  *    from this software without specific prior written permission.
   22  *
   23  * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
   24  * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
   25  * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
   26  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
   27  * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
   28  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
   29  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
   30  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
   31  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
   32  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
   33  * POSSIBILITY OF SUCH DAMAGE.
   34  */
   35 
   36 #include <sys/cdefs.h>
   37 __KERNEL_RCSID(0, "$NetBSD: nullcons_subr.c,v 1.4 2005/12/11 12:20:53 christos Exp $");
   38 
   39 #include <sys/param.h>
   40 #include <sys/proc.h>
   41 #include <sys/user.h>
   42 #include <sys/systm.h>
   43 #include <sys/buf.h>
   44 #include <sys/ioctl.h>
   45 #include <sys/tty.h>
   46 #include <sys/file.h>
   47 #include <sys/conf.h>
   48 #include <sys/vnode.h>
   49 
   50 #include <dev/cons.h>
   51 
   52 
   53 extern struct consdev *cn_tab;          /* physical console device info */
   54 
   55 static struct tty *nulltty;             /* null console tty */
   56 
   57 cons_decl(null);
   58 
   59 dev_type_read(nullcndev_read);
   60 dev_type_ioctl(nullcndev_ioctl);
   61 dev_type_tty(nullcndev_tty);
   62 
   63 static int      nullcons_newdev(struct consdev *);
   64 
   65 const struct cdevsw nullcn_devsw = {
   66         nullopen, nullclose, nullcndev_read, nullwrite, nullcndev_ioctl,
   67         nullstop, nullcndev_tty, nopoll, nommap, ttykqfilter, D_TTY
   68 };
   69 
   70 /*
   71  * null console device. We need it because of the ioctl() it handles,
   72  * which in particular allows control terminal allocation through
   73  * TIOCSCTTY ioctl. Without the latter, system won't even boot past init(8)
   74  * invocation.
   75  */
   76 int
   77 nullcndev_read(dev, uio, flag)
   78         dev_t dev;
   79         struct uio *uio;
   80         int flag;
   81 {
   82 
   83         for(;;);
   84         return (0);
   85 }
   86 
   87 int
   88 nullcndev_ioctl(dev, cmd, data, flag, l)
   89         dev_t dev;
   90         u_long cmd;
   91         caddr_t data;
   92         int flag;
   93         struct lwp *l;
   94 {
   95         int error;
   96 
   97         error = (*nulltty->t_linesw->l_ioctl)(nulltty, cmd, data, flag, l);
   98         if (error != EPASSTHROUGH)
   99                 return (error);
  100 
  101         error = ttioctl(nulltty, cmd, data, flag, l);
  102         if (error != EPASSTHROUGH)
  103                 return (error);
  104 
  105         return (0);
  106 }
  107 
  108 struct tty*
  109 nullcndev_tty(dev)
  110         dev_t dev;
  111 {
  112 
  113         return nulltty;
  114 }
  115 
  116 /*
  117  * Mark console as no-op (null) console. Proper initialization is deferred
  118  * to nullconsattach().
  119  */
  120 void
  121 nullcnprobe(cn)
  122         struct consdev *cn;
  123 {
  124 
  125         cn->cn_pri = CN_NULL;
  126         cn->cn_dev = NODEV;
  127 }
  128 
  129 /*
  130  * null console initialization. This includes allocation of a new device and
  131  * a new tty.
  132  */
  133 void
  134 nullcninit(cn)
  135         struct consdev *cn;
  136 {
  137         static struct consdev nullcn = cons_init(null);
  138 
  139         nullcnprobe(&nullcn);
  140         cn_tab = &nullcn;
  141 }
  142 
  143 /*
  144  * Dumb getc() implementation. Simply blocks on call.
  145  */
  146 int
  147 nullcngetc(dev)
  148         dev_t dev;
  149 {
  150 
  151         for(;;);
  152         return (0);
  153 }
  154 
  155 /*
  156  * Dumb putc() implementation.
  157  */
  158 void
  159 nullcnputc(dev, c)
  160         dev_t dev;
  161         int c;
  162 {
  163 
  164 }
  165 
  166 /*
  167  * Allocate a new console device and a tty to handle console ioctls.
  168  */
  169 int
  170 nullcons_newdev(cn)
  171         struct consdev *cn;
  172 {
  173         int error;
  174         int bmajor = -1, cmajor = -1;
  175 
  176         if ((cn == NULL) || (cn->cn_pri != CN_NULL) || (cn->cn_dev != NODEV))
  177                 return (0);
  178 
  179         /*
  180          * Attach no-op device to the device list.
  181          */
  182         error = devsw_attach("nullcn", NULL, &bmajor, &nullcn_devsw, &cmajor);
  183         if (error != 0)
  184                 return (error);
  185 
  186         /*
  187          * Allocate tty (mostly to have sane ioctl()).
  188          */
  189         nulltty = ttymalloc();
  190         nulltty->t_dev = makedev(cmajor, 0);
  191         tty_attach(nulltty);
  192         cn->cn_dev = nulltty->t_dev;
  193 
  194         return (0);
  195 }
  196 
  197 /*
  198  * Pseudo-device attach function -- it's the right time to do the rest of
  199  * initialization.
  200  */
  201 void
  202 nullconsattach(pdev_count)
  203         int pdev_count;
  204 {
  205 
  206         nullcons_newdev(cn_tab);
  207 }

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