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 "opt_compat.h"
  41
  42 #include <sys/param.h>
  43 #include <sys/systm.h>
  44 #include <sys/tty.h>
  45 #include <sys/conf.h>
  46
  47 #ifndef MAXLDISC
  48 #define MAXLDISC 9
  49 #endif
  50
  51 static l_open_t         l_noopen;
  52 static l_close_t        l_noclose;
  53 static l_rint_t         l_norint;
  54 static l_start_t        l_nostart;
  55
  56 /*
  57  * XXX it probably doesn't matter what the entries other than the l_open
  58  * entry are here.  The l_nullioctl and ttymodem entries still look fishy.
  59  * Reconsider the removal of nullmodem anyway.  It was too much like
  60  * ttymodem, but a completely null version might be useful.
  61  */
  62 #define NODISC(n) \
  63         { l_noopen,     l_noclose,      l_noread,       l_nowrite, \
  64           l_nullioctl,  l_norint,       l_nostart,      ttymodem }
  65
  66 struct  linesw linesw[MAXLDISC] =
  67 {
  68                                 /* 0- termios */
  69         { ttyopen,      ttylclose,      ttread,         ttwrite,
  70           l_nullioctl,  ttyinput,       ttstart,        ttymodem },
  71         NODISC(1),              /* 1- defunct */
  72                                 /* 2- NTTYDISC */
  73 #ifdef COMPAT_43
  74         { ttyopen,      ttylclose,      ttread,         ttwrite,
  75           l_nullioctl,  ttyinput,       ttstart,        ttymodem },
  76 #else
  77         NODISC(2),
  78 #endif
  79         NODISC(3),              /* loadable */
  80         NODISC(4),              /* SLIPDISC */
  81         NODISC(5),              /* PPPDISC */
  82         NODISC(6),              /* NETGRAPHDISC */
  83         NODISC(7),              /* loadable */
  84         NODISC(8),              /* loadable */
  85 };
  86
  87 int     nlinesw = NELEM(linesw);
  88
  89 static struct linesw nodisc = NODISC(0);
  90
  91 #define LOADABLE_LDISC 7
  92 /*
  93  * ldisc_register: Register a line discipline.
  94  *
  95  * discipline: Index for discipline to load, or LDISC_LOAD for us to choose.
  96  * linesw_p:   Pointer to linesw_p.
  97  *
  98  * Returns: Index used or -1 on failure.
  99  */
 100 int
 101 ldisc_register(int discipline, struct linesw *linesw_p)
 102 {
 103         int slot = -1;
 104
 105         lwkt_gettoken(&tty_token);
 106         if (discipline == LDISC_LOAD) {
 107                 int i;
 108                 for (i = LOADABLE_LDISC; i < MAXLDISC; i++)
 109                         if (bcmp(linesw + i, &nodisc, sizeof(nodisc)) == 0) {
 110                                 slot = i;
 111                         }
 112         }
 113         else if (discipline >= 0 && discipline < MAXLDISC) {
 114                 slot = discipline;
 115         }
 116
 117         if (slot != -1 && linesw_p)
 118                 linesw[slot] = *linesw_p;
 119
 120         lwkt_reltoken(&tty_token);
 121         return slot;
 122 }
 123
 124 /*
 125  * ldisc_deregister: Deregister a line discipline obtained with
 126  * ldisc_register.
 127  *
 128  * discipline: Index for discipline to unload.
 129  */
 130 void
 131 ldisc_deregister(int discipline)
 132 {
 133         lwkt_gettoken(&tty_token);
 134         if (discipline < MAXLDISC) {
 135                 linesw[discipline] = nodisc;
 136         }
 137         lwkt_reltoken(&tty_token);
 138 }
 139
 140 static int
 141 l_noopen(cdev_t dev, struct tty *tp)
 142 {
 143
 144         return (ENODEV);
 145 }
 146
 147 static int
 148 l_noclose(struct tty *tp, int flag)
 149 {
 150
 151         return (ENODEV);
 152 }
 153
 154 int
 155 l_noread(struct tty *tp, struct uio *uio, int flag)
 156 {
 157
 158         return (ENODEV);
 159 }
 160
 161 int
 162 l_nowrite(struct tty *tp, struct uio *uio, int flag)
 163 {
 164
 165         return (ENODEV);
 166 }
 167
 168 static int
 169 l_norint(int c, struct tty *tp)
 170 {
 171
 172         return (ENODEV);
 173 }
 174
 175 static int
 176 l_nostart(struct tty *tp)
 177 {
 178
 179         return (ENODEV);
 180 }
 181
 182 /*
 183  * Do nothing specific version of line
 184  * discipline specific ioctl command.
 185  */
 186 int
 187 l_nullioctl(struct tty *tp, u_long cmd, char *data, int flags,
 188             struct ucred *cred)
 189 {
 190
 191         return (ENOIOCTL);
 192 }