sys/kern/tty_conf.c

   1 /*-
   2  * (MPSAFE)
   3  *
   4  * Copyright (c) 1982, 1986, 1991, 1993
   5  *      The Regents of the University of California.  All rights reserved.
   6  * (c) UNIX System Laboratories, Inc.
   7  * All or some portions of this file are derived from material licensed
   8  * to the University of California by American Telephone and Telegraph
   9  * Co. or Unix System Laboratories, Inc. and are reproduced herein with
  10  * the permission of UNIX System Laboratories, Inc.
  11  *
  12  * Redistribution and use in source and binary forms, with or without
  13  * modification, are permitted provided that the following conditions
  14  * are met:
  15  * 1. Redistributions of source code must retain the above copyright
  16  *    notice, this list of conditions and the following disclaimer.
  17  * 2. Redistributions in binary form must reproduce the above copyright
  18  *    notice, this list of conditions and the following disclaimer in the
  19  *    documentation and/or other materials provided with the distribution.
  20  * 3. Neither the name of the University nor the names of its contributors
  21  *    may be used to endorse or promote products derived from this software
  22  *    without specific prior written permission.
  23  *
  24  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  25  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  26  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  27  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  28  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  29  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  30  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  31  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  32  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  33  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  34  * SUCH DAMAGE.
  35  *
  36  *      @(#)tty_conf.c  8.4 (Berkeley) 1/21/94
  37  * $FreeBSD: src/sys/kern/tty_conf.c,v 1.16.2.1 2002/03/11 01:14:55 dd Exp $
  38  */
  39
  40 #include <sys/param.h>
  41 #include <sys/systm.h>
  42 #include <sys/tty.h>
  43 #include <sys/conf.h>
  44
  45 #ifndef MAXLDISC
  46 #define MAXLDISC 9
  47 #endif
  48
  49 static l_open_t         l_noopen;
  50 static l_close_t        l_noclose;
  51 static l_rint_t         l_norint;
  52 static l_start_t        l_nostart;
  53
  54 /*
  55  * XXX it probably doesn't matter what the entries other than the l_open
  56  * entry are here.  The l_nullioctl and ttymodem entries still look fishy.
  57  * Reconsider the removal of nullmodem anyway.  It was too much like
  58  * ttymodem, but a completely null version might be useful.
  59  */
  60 #define NODISC(n) \
  61         { l_noopen,     l_noclose,      l_noread,       l_nowrite, \
  62           l_nullioctl,  l_norint,       l_nostart,      ttymodem }
  63
  64 struct  linesw linesw[MAXLDISC] =
  65 {
  66                                 /* 0- termios */
  67         { ttyopen,      ttylclose,      ttread,         ttwrite,
  68           l_nullioctl,  ttyinput,       ttstart,        ttymodem },
  69         NODISC(1),              /* 1- defunct */
  70         NODISC(2),              /* 2- NTTYDISC */
  71         NODISC(3),              /* loadable */
  72         NODISC(4),              /* SLIPDISC */
  73         NODISC(5),              /* PPPDISC */
  74         NODISC(6),              /* NETGRAPHDISC */
  75         NODISC(7),              /* loadable */
  76         NODISC(8),              /* loadable */
  77 };
  78
  79 int     nlinesw = NELEM(linesw);
  80
  81 static struct linesw nodisc = NODISC(0);
  82
  83 #define LOADABLE_LDISC 7
  84 /*
  85  * ldisc_register: Register a line discipline.
  86  *
  87  * discipline: Index for discipline to load, or LDISC_LOAD for us to choose.
  88  * linesw_p:   Pointer to linesw_p.
  89  *
  90  * Returns: Index used or -1 on failure.
  91  */
  92 int
  93 ldisc_register(int discipline, struct linesw *linesw_p)
  94 {
  95         int slot = -1;
  96
  97         lwkt_gettoken(&tty_token);
  98         if (discipline == LDISC_LOAD) {
  99                 int i;
 100                 for (i = LOADABLE_LDISC; i < MAXLDISC; i++)
 101                         if (bcmp(linesw + i, &nodisc, sizeof(nodisc)) == 0) {
 102                                 slot = i;
 103                         }
 104         }
 105         else if (discipline >= 0 && discipline < MAXLDISC) {
 106                 slot = discipline;
 107         }
 108
 109         if (slot != -1 && linesw_p)
 110                 linesw[slot] = *linesw_p;
 111
 112         lwkt_reltoken(&tty_token);
 113         return slot;
 114 }
 115
 116 /*
 117  * ldisc_deregister: Deregister a line discipline obtained with
 118  * ldisc_register.
 119  *
 120  * discipline: Index for discipline to unload.
 121  */
 122 void
 123 ldisc_deregister(int discipline)
 124 {
 125         lwkt_gettoken(&tty_token);
 126         if (discipline < MAXLDISC) {
 127                 linesw[discipline] = nodisc;
 128         }
 129         lwkt_reltoken(&tty_token);
 130 }
 131
 132 static int
 133 l_noopen(cdev_t dev, struct tty *tp)
 134 {
 135
 136         return (ENODEV);
 137 }
 138
 139 static int
 140 l_noclose(struct tty *tp, int flag)
 141 {
 142
 143         return (ENODEV);
 144 }
 145
 146 int
 147 l_noread(struct tty *tp, struct uio *uio, int flag)
 148 {
 149
 150         return (ENODEV);
 151 }
 152
 153 int
 154 l_nowrite(struct tty *tp, struct uio *uio, int flag)
 155 {
 156
 157         return (ENODEV);
 158 }
 159
 160 static int
 161 l_norint(int c, struct tty *tp)
 162 {
 163
 164         return (ENODEV);
 165 }
 166
 167 static int
 168 l_nostart(struct tty *tp)
 169 {
 170
 171         return (ENODEV);
 172 }
 173
 174 /*
 175  * Do nothing specific version of line
 176  * discipline specific ioctl command.
 177  */
 178 int
 179 l_nullioctl(struct tty *tp, u_long cmd, char *data, int flags,
 180             struct ucred *cred)
 181 {
 182
 183         return (ENOIOCTL);
 184 }