1 /* $NetBSD: nullcons_subr.c,v 1.13 2014/07/25 08:10:35 dholland Exp $ */
2
3 /*-
4 * Copyright (c) 2003 The NetBSD Foundation, Inc.
5 * All rights reserved.
6 *
7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that the following conditions
9 * are met:
10 * 1. Redistributions of source code must retain the above copyright
11 * notice, this list of conditions and the following disclaimer.
12 * 2. Redistributions in binary form must reproduce the above copyright
13 * notice, this list of conditions and the following disclaimer in the
14 * documentation and/or other materials provided with the distribution.
15 *
16 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
17 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
18 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
19 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
20 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
21 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
22 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
23 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
24 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
25 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
26 * POSSIBILITY OF SUCH DAMAGE.
27 */
28
29 #include <sys/cdefs.h>
30 __KERNEL_RCSID(0, "$NetBSD: nullcons_subr.c,v 1.13 2014/07/25 08:10:35 dholland Exp $");
31
32 #include <sys/param.h>
33 #include <sys/proc.h>
34 #include <sys/systm.h>
35 #include <sys/buf.h>
36 #include <sys/ioctl.h>
37 #include <sys/tty.h>
38 #include <sys/file.h>
39 #include <sys/conf.h>
40 #include <sys/vnode.h>
41
42 #include <dev/cons.h>
43
44 static struct tty *nulltty; /* null console tty */
45
46 cons_decl(null);
47
48 dev_type_read(nullcndev_read);
49 dev_type_ioctl(nullcndev_ioctl);
50 dev_type_tty(nullcndev_tty);
51
52 static int nullcons_newdev(struct consdev *);
53
54 const struct cdevsw nullcn_devsw = {
55 .d_open = nullopen,
56 .d_close = nullclose,
57 .d_read = nullcndev_read,
58 .d_write = nullwrite,
59 .d_ioctl = nullcndev_ioctl,
60 .d_stop = nullstop,
61 .d_tty = nullcndev_tty,
62 .d_poll = nopoll,
63 .d_mmap = nommap,
64 .d_kqfilter = ttykqfilter,
65 .d_discard = nodiscard,
66 .d_flag = D_TTY
67 };
68
69 /*
70 * null console device. We need it because of the ioctl() it handles,
71 * which in particular allows control terminal allocation through
72 * TIOCSCTTY ioctl. Without the latter, system won't even boot past init(8)
73 * invocation.
74 */
75 int
nullcndev_read(dev_t dev,struct uio * uio,int flag)76 nullcndev_read(dev_t dev, struct uio *uio, int flag)
77 {
78
79 return EIO;
80 }
81
82 int
nullcndev_ioctl(dev_t dev,u_long cmd,void * data,int flag,struct lwp * l)83 nullcndev_ioctl(dev_t dev, u_long cmd, void *data, int flag, struct lwp *l)
84 {
85 int error;
86
87 error = (*nulltty->t_linesw->l_ioctl)(nulltty, cmd, data, flag, l);
88 if (error != EPASSTHROUGH)
89 return error;
90
91 error = ttioctl(nulltty, cmd, data, flag, l);
92 if (error != EPASSTHROUGH)
93 return error;
94
95 return 0;
96 }
97
98 struct tty*
nullcndev_tty(dev_t dev)99 nullcndev_tty(dev_t dev)
100 {
101
102 return nulltty;
103 }
104
105 /*
106 * Mark console as no-op (null) console. Proper initialization is deferred
107 * to nullconsattach().
108 */
109 void
nullcnprobe(struct consdev * cn)110 nullcnprobe(struct consdev *cn)
111 {
112
113 cn->cn_pri = CN_NULL;
114 cn->cn_dev = NODEV;
115 }
116
117 /*
118 * null console initialization. This includes allocation of a new device and
119 * a new tty.
120 */
121 void
nullcninit(struct consdev * cn)122 nullcninit(struct consdev *cn)
123 {
124 static struct consdev nullcn = cons_init(null);
125
126 nullcnprobe(&nullcn);
127 cn_tab = &nullcn;
128 }
129
130 /*
131 * Dumb getc() implementation. Simply blocks on call.
132 */
133 int
nullcngetc(dev_t dev)134 nullcngetc(dev_t dev)
135 {
136
137 for (;;)
138 ;
139 return 0;
140 }
141
142 /*
143 * Dumb putc() implementation.
144 */
145 void
nullcnputc(dev_t dev,int c)146 nullcnputc(dev_t dev, int c)
147 {
148
149 }
150
151 /*
152 * Allocate a new console device and a tty to handle console ioctls.
153 */
154 int
nullcons_newdev(struct consdev * cn)155 nullcons_newdev(struct consdev *cn)
156 {
157 int error;
158 int bmajor = -1, cmajor = -1;
159
160 if ((cn == NULL) || (cn->cn_pri != CN_NULL) || (cn->cn_dev != NODEV))
161 return 0;
162
163 /*
164 * Attach no-op device to the device list.
165 */
166 error = devsw_attach("nullcn", NULL, &bmajor, &nullcn_devsw, &cmajor);
167 if (error != 0)
168 return error;
169
170 /*
171 * Allocate tty (mostly to have sane ioctl()).
172 */
173 nulltty = tty_alloc();
174 nulltty->t_dev = makedev(cmajor, 0);
175 tty_attach(nulltty);
176 cn->cn_dev = nulltty->t_dev;
177
178 return 0;
179 }
180
181 /*
182 * Pseudo-device attach function -- it's the right time to do the rest of
183 * initialization.
184 */
185 void
nullconsattach(int pdev_count)186 nullconsattach(int pdev_count)
187 {
188
189 nullcons_newdev(cn_tab);
190 }
191