sys/kern/tty_conf.c

   1 /*      $NetBSD: tty_conf.c,v 1.54 2007/11/07 15:56:22 ad Exp $ */
   2
   3 /*-
   4  * Copyright (c) 2005, 2007 The NetBSD Foundation, Inc.
   5  * All rights reserved.
   6  *
   7  * This code is derived from software contributed to The NetBSD Foundation
   8  * by Jason R. Thorpe.
   9  *
  10  * Redistribution and use in source and binary forms, with or without
  11  * modification, are permitted provided that the following conditions
  12  * are met:
  13  * 1. Redistributions of source code must retain the above copyright
  14  *    notice, this list of conditions and the following disclaimer.
  15  * 2. Redistributions in binary form must reproduce the above copyright
  16  *    notice, this list of conditions and the following disclaimer in the
  17  *    documentation and/or other materials provided with the distribution.
  18  *
  19  * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
  20  * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
  21  * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
  22  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
  23  * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
  24  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
  25  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
  26  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
  27  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
  28  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
  29  * POSSIBILITY OF SUCH DAMAGE.
  30  */
  31
  32 /*-
  33  * Copyright (c) 1982, 1986, 1991, 1993
  34  *      The Regents of the University of California.  All rights reserved.
  35  * (c) UNIX System Laboratories, Inc.
  36  * All or some portions of this file are derived from material licensed
  37  * to the University of California by American Telephone and Telegraph
  38  * Co. or Unix System Laboratories, Inc. and are reproduced herein with
  39  * the permission of UNIX System Laboratories, Inc.
  40  *
  41  * Redistribution and use in source and binary forms, with or without
  42  * modification, are permitted provided that the following conditions
  43  * are met:
  44  * 1. Redistributions of source code must retain the above copyright
  45  *    notice, this list of conditions and the following disclaimer.
  46  * 2. Redistributions in binary form must reproduce the above copyright
  47  *    notice, this list of conditions and the following disclaimer in the
  48  *    documentation and/or other materials provided with the distribution.
  49  * 3. Neither the name of the University nor the names of its contributors
  50  *    may be used to endorse or promote products derived from this software
  51  *    without specific prior written permission.
  52  *
  53  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  54  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  55  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  56  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  57  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  58  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  59  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  60  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  61  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  62  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  63  * SUCH DAMAGE.
  64  *
  65  *      @(#)tty_conf.c  8.5 (Berkeley) 1/9/95
  66  */
  67
  68 #include <sys/cdefs.h>
  69 __KERNEL_RCSID(0, "$NetBSD: tty_conf.c,v 1.54 2007/11/07 15:56:22 ad Exp $");
  70
  71 #include <sys/param.h>
  72 #include <sys/systm.h>
  73 #include <sys/poll.h>
  74 #include <sys/proc.h>
  75 #include <sys/tty.h>
  76 #include <sys/ttycom.h>
  77 #include <sys/conf.h>
  78 #include <sys/mutex.h>
  79 #include <sys/queue.h>
  80
  81 static struct linesw termios_disc = {
  82         .l_name = "termios",
  83         .l_open = ttylopen,
  84         .l_close = ttylclose,
  85         .l_read = ttread,
  86         .l_write = ttwrite,
  87         .l_ioctl = ttynullioctl,
  88         .l_rint = ttyinput,
  89         .l_start = ttstart,
  90         .l_modem = ttymodem,
  91         .l_poll = ttpoll
  92 };
  93
  94 /*
  95  * This is for the benefit of old BSD TTY compatbility, but since it is
  96  * identical to termios (except for the name), don't bother conditionalizing
  97  * it.
  98  */
  99 static struct linesw ntty_disc = {      /* old NTTYDISC */
 100         .l_name = "ntty",
 101         .l_open = ttylopen,
 102         .l_close = ttylclose,
 103         .l_read = ttread,
 104         .l_write = ttwrite,
 105         .l_ioctl = ttynullioctl,
 106         .l_rint = ttyinput,
 107         .l_start = ttstart,
 108         .l_modem = ttymodem,
 109         .l_poll = ttpoll
 110 };
 111
 112 static LIST_HEAD(, linesw) ttyldisc_list = LIST_HEAD_INITIALIZER(ttyldisc_head);
 113
 114 /*
 115  * Note: We don't bother refcounting termios_disc and ntty_disc; they can't
 116  * be removed from the list, and termios_disc is likely to have very many
 117  * references (could we overflow the count?).
 118  */
 119 #define TTYLDISC_ISSTATIC(disc)                                 \
 120         ((disc) == &termios_disc || (disc) == &ntty_disc)
 121
 122 #define TTYLDISC_HOLD(disc)                                     \
 123 do {                                                            \
 124         if (! TTYLDISC_ISSTATIC(disc)) {                        \
 125                 KASSERT((disc)->l_refcnt != UINT_MAX);          \
 126                 (disc)->l_refcnt++;                             \
 127         }                                                       \
 128 } while (/*CONSTCOND*/0)
 129
 130 #define TTYLDISC_RELE(disc)                                     \
 131 do {                                                            \
 132         if (! TTYLDISC_ISSTATIC(disc)) {                        \
 133                 KASSERT((disc)->l_refcnt != 0);                 \
 134                 (disc)->l_refcnt--;                             \
 135         }                                                       \
 136 } while (/*CONSTCOND*/0)
 137
 138 #define TTYLDISC_ISINUSE(disc)                                  \
 139         (TTYLDISC_ISSTATIC(disc) || (disc)->l_refcnt != 0)
 140
 141 /*
 142  * Do nothing specific version of line
 143  * discipline specific ioctl command.
 144  */
 145 /*ARGSUSED*/
 146 int
 147 ttynullioctl(struct tty *tp, u_long cmd, void *data, int flags, struct lwp *l)
 148 {
 149
 150         return (EPASSTHROUGH);
 151 }
 152
 153 /*
 154  * Return error to line discipline
 155  * specific poll call.
 156  */
 157 /*ARGSUSED*/
 158 int
 159 ttyerrpoll(struct tty *tp, int events, struct lwp *l)
 160 {
 161
 162         return (POLLERR);
 163 }
 164
 165 void
 166 ttyldisc_init(void)
 167 {
 168
 169         if (ttyldisc_attach(&termios_disc) != 0)
 170                 panic("ttyldisc_init: termios_disc");
 171         if (ttyldisc_attach(&ntty_disc) != 0)
 172                 panic("ttyldisc_init: ntty_disc");
 173 }
 174
 175 static struct linesw *
 176 ttyldisc_lookup_locked(const char *name)
 177 {
 178         struct linesw *disc;
 179
 180         LIST_FOREACH(disc, &ttyldisc_list, l_list) {
 181                 if (strcmp(name, disc->l_name) == 0)
 182                         return (disc);
 183         }
 184
 185         return (NULL);
 186 }
 187
 188 /*
 189  * Look up a line discipline by its name.  Caller holds a reference on
 190  * the returned line discipline.
 191  */
 192 struct linesw *
 193 ttyldisc_lookup(const char *name)
 194 {
 195         struct linesw *disc;
 196
 197         mutex_spin_enter(&tty_lock);
 198         disc = ttyldisc_lookup_locked(name);
 199         if (disc != NULL)
 200                 TTYLDISC_HOLD(disc);
 201         mutex_spin_exit(&tty_lock);
 202
 203         return (disc);
 204 }
 205
 206 /*
 207  * Look up a line discipline by its legacy number.  Caller holds a
 208  * reference on the returned line discipline.
 209  */
 210 struct linesw *
 211 ttyldisc_lookup_bynum(int num)
 212 {
 213         struct linesw *disc;
 214
 215         mutex_spin_enter(&tty_lock);
 216
 217         LIST_FOREACH(disc, &ttyldisc_list, l_list) {
 218                 if (disc->l_no == num) {
 219                         TTYLDISC_HOLD(disc);
 220                         mutex_spin_exit(&tty_lock);
 221                         return (disc);
 222                 }
 223         }
 224
 225         mutex_spin_exit(&tty_lock);
 226         return (NULL);
 227 }
 228
 229 /*
 230  * Release a reference on a line discipline previously added by
 231  * ttyldisc_lookup() or ttyldisc_lookup_bynum().
 232  */
 233 void
 234 ttyldisc_release(struct linesw *disc)
 235 {
 236
 237         if (disc == NULL)
 238                 return;
 239
 240         mutex_spin_enter(&tty_lock);
 241         TTYLDISC_RELE(disc);
 242         mutex_spin_exit(&tty_lock);
 243 }
 244
 245 #define TTYLDISC_LEGACY_NUMBER_MIN      10
 246 #define TTYLDISC_LEGACY_NUMBER_MAX      INT_MAX
 247
 248 static void
 249 ttyldisc_assign_legacy_number(struct linesw *disc)
 250 {
 251         static const struct {
 252                 const char *name;
 253                 int num;
 254         } table[] = {
 255                 { "termios",            TTYDISC },
 256                 { "ntty",               2 /* XXX old NTTYDISC */ },
 257                 { "tablet",             TABLDISC },
 258                 { "slip",               SLIPDISC },
 259                 { "ppp",                PPPDISC },
 260                 { "strip",              STRIPDISC },
 261                 { "hdlc",               HDLCDISC },
 262                 { NULL,                 0 }
 263         };
 264         struct linesw *ldisc;
 265         int i;
 266
 267         for (i = 0; table[i].name != NULL; i++) {
 268                 if (strcmp(disc->l_name, table[i].name) == 0) {
 269                         disc->l_no = table[i].num;
 270                         return;
 271                 }
 272         }
 273
 274         disc->l_no = TTYLDISC_LEGACY_NUMBER_MIN;
 275
 276         LIST_FOREACH(ldisc, &ttyldisc_list, l_list) {
 277                 if (disc->l_no == ldisc->l_no) {
 278                         KASSERT(disc->l_no < TTYLDISC_LEGACY_NUMBER_MAX);
 279                         disc->l_no++;
 280                 }
 281         }
 282 }
 283
 284 /*
 285  * Register a line discipline.
 286  */
 287 int
 288 ttyldisc_attach(struct linesw *disc)
 289 {
 290
 291         KASSERT(disc->l_name != NULL);
 292         KASSERT(disc->l_open != NULL);
 293         KASSERT(disc->l_close != NULL);
 294         KASSERT(disc->l_read != NULL);
 295         KASSERT(disc->l_write != NULL);
 296         KASSERT(disc->l_ioctl != NULL);
 297         KASSERT(disc->l_rint != NULL);
 298         KASSERT(disc->l_start != NULL);
 299         KASSERT(disc->l_modem != NULL);
 300         KASSERT(disc->l_poll != NULL);
 301
 302         /* You are not allowed to exceed TTLINEDNAMELEN */
 303         if (strlen(disc->l_name) >= TTLINEDNAMELEN)
 304                 return (ENAMETOOLONG);
 305
 306         mutex_spin_enter(&tty_lock);
 307
 308         if (ttyldisc_lookup_locked(disc->l_name) != NULL) {
 309                 mutex_spin_exit(&tty_lock);
 310                 return (EEXIST);
 311         }
 312
 313         ttyldisc_assign_legacy_number(disc);
 314         LIST_INSERT_HEAD(&ttyldisc_list, disc, l_list);
 315
 316         mutex_spin_exit(&tty_lock);
 317
 318         return (0);
 319 }
 320
 321 /*
 322  * Remove a line discipline.
 323  */
 324 int
 325 ttyldisc_detach(struct linesw *disc)
 326 {
 327 #ifdef DIAGNOSTIC
 328         struct linesw *ldisc = ttyldisc_lookup(disc->l_name);
 329
 330         KASSERT(ldisc != NULL);
 331         KASSERT(ldisc == disc);
 332         ttyldisc_release(ldisc);
 333 #endif
 334
 335         mutex_spin_enter(&tty_lock);
 336
 337         if (TTYLDISC_ISINUSE(disc)) {
 338                 mutex_spin_exit(&tty_lock);
 339                 return (EBUSY);
 340         }
 341
 342         LIST_REMOVE(disc, l_list);
 343
 344         mutex_spin_exit(&tty_lock);
 345
 346         return (0);
 347 }
 348
 349 /*
 350  * Return the default line discipline.
 351  */
 352 struct linesw *
 353 ttyldisc_default(void)
 354 {
 355
 356         return (&termios_disc);
 357 }