FreeBSD/Linux Kernel Cross Reference
sys/kern/tty_conf.c
1 /* $NetBSD: tty_conf.c,v 1.55 2008/04/28 20:24:05 martin 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 1.55 2008/04/28 20:24:05 martin 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 }
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