FreeBSD/Linux Kernel Cross Reference
sys/kern/tty_conf.c

     /*-
      * Copyright (c) 1982, 1986, 1991, 1993
      *      The Regents of the University of California.  All rights reserved.
      * (c) UNIX System Laboratories, Inc.
      * All or some portions of this file are derived from material licensed
      * to the University of California by American Telephone and Telegraph
      * Co. or Unix System Laboratories, Inc. and are reproduced herein with
      * the permission of UNIX System Laboratories, Inc.
      *
     * Redistribution and use in source and binary forms, with or without
     * modification, are permitted provided that the following conditions
     * are met:
     * 1. Redistributions of source code must retain the above copyright
     *    notice, this list of conditions and the following disclaimer.
     * 2. Redistributions in binary form must reproduce the above copyright
     *    notice, this list of conditions and the following disclaimer in the
     *    documentation and/or other materials provided with the distribution.
     * 3. All advertising materials mentioning features or use of this software
     *    must display the following acknowledgement:
     *      This product includes software developed by the University of
     *      California, Berkeley and its contributors.
     * 4. Neither the name of the University nor the names of its contributors
     *    may be used to endorse or promote products derived from this software
     *    without specific prior written permission.
     *
     * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
     * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
     * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
     * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
     * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
     * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
     * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
     * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     * SUCH DAMAGE.
     *
     *      @(#)tty_conf.c  8.4 (Berkeley) 1/21/94
     * $FreeBSD: src/sys/kern/tty_conf.c,v 1.8.4.1 1999/09/05 08:15:27 peter Exp $
     */
    
    #include <sys/param.h>
    #include <sys/systm.h>
    #include <sys/tty.h>
    #include <sys/conf.h>
    
    #ifndef MAXLDISC
    #define MAXLDISC 8
    #endif
    
    static l_open_t         l_noopen;
    static l_close_t        l_noclose;
    static l_ioctl_t        l_nullioctl;
    static l_rint_t         l_norint;
    static l_start_t        l_nostart;
    
    /*
     * XXX it probably doesn't matter what the entries other than the l_open
     * entry are here.  The l_nullioctl and ttymodem entries still look fishy.
     * Reconsider the removal of nullmodem anyway.  It was too much like
     * ttymodem, but a completely null version might be useful.
     */
    #define NODISC(n) \
            { l_noopen,     l_noclose,      l_noread,       l_nowrite, \
              l_nullioctl,  l_norint,       l_nostart,      ttymodem }
    
    struct  linesw linesw[MAXLDISC] =
    {
                                    /* 0- termios */
            { ttyopen,      ttylclose,      ttread,         ttwrite,
              l_nullioctl,  ttyinput,       ttstart,        ttymodem },
            NODISC(1),              /* 1- defunct */
                                    /* 2- NTTYDISC */
    #ifdef COMPAT_43
            { ttyopen,      ttylclose,      ttread,         ttwrite,
              l_nullioctl,  ttyinput,       ttstart,        ttymodem },
    #else
            NODISC(2),
    #endif
            NODISC(3),              /* TABLDISC */
            NODISC(4),              /* SLIPDISC */
            NODISC(5),              /* PPPDISC */
            NODISC(6),              /* loadable */
            NODISC(7),              /* loadable */
    };
    
    int     nlinesw = sizeof (linesw) / sizeof (linesw[0]);
    
    static struct linesw nodisc = NODISC(0);
    
    #define LOADABLE_LDISC 6
    /*
     * ldisc_register: Register a line discipline.
     *
     * discipline: Index for discipline to load, or LDISC_LOAD for us to choose.
     * linesw_p:   Pointer to linesw_p.
     *
     * Returns: Index used or -1 on failure.
     */
   int
   ldisc_register(discipline, linesw_p)
           int discipline;
           struct linesw *linesw_p;
   {
           int slot = -1;
   
           if (discipline == LDISC_LOAD) {
                   int i;
                   for (i = LOADABLE_LDISC; i < MAXLDISC; i++)
                           if (bcmp(linesw + i, &nodisc, sizeof(nodisc)) == 0) {
                                   slot = i;
                           }
           }
           else if (discipline >= 0 && discipline < MAXLDISC) {
                   slot = discipline;
           }
   
           if (slot != -1 && linesw_p)
                   linesw[slot] = *linesw_p;
   
           return slot;
   }
   
   /*
    * ldisc_deregister: Deregister a line discipline obtained with
    * ldisc_register.  Can only deregister "loadable" ones now.
    *
    * discipline: Index for discipline to unload.
    */
   void
   ldisc_deregister(discipline)
           int discipline;
   {
           if (discipline >= LOADABLE_LDISC && discipline < MAXLDISC) {
                   linesw[discipline] = nodisc;
           }
   }
   
   static int
   l_noopen(dev, tp)
           dev_t dev;
           struct tty *tp;
   {
   
           return (ENODEV);
   }
   
   static int
   l_noclose(tp, flag)
           struct tty *tp;
           int flag;
   {
   
           return (ENODEV);
   }
   
   int
   l_noread(tp, uio, flag)
           struct tty *tp;
           struct uio *uio;
           int flag;
   {
   
           return (ENODEV);
   }
   
   int
   l_nowrite(tp, uio, flag)
           struct tty *tp;
           struct uio *uio;
           int flag;
   {
   
           return (ENODEV);
   }
   
   static int
   l_norint(c, tp)
           int c;
           struct tty *tp;
   {
   
           return (ENODEV);
   }
   
   static int
   l_nostart(tp)
           struct tty *tp;
   {
   
           return (ENODEV);
   }
   
   /*
    * Do nothing specific version of line
    * discipline specific ioctl command.
    */
   static int
   l_nullioctl(tp, cmd, data, flags, p)
           struct tty *tp;
           int cmd;
           char *data;
           int flags;
           struct proc *p;
   {
   
           return (-1);
   }

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