1 /* $NetBSD: nullcons_subr.c,v 1.9 2009/04/16 12:57:22 tsutsui 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 1.9 2009/04/16 12:57:22 tsutsui Exp $"); 31 32 #include <sys/param.h> 33 #include <sys/proc.h> 34 #include <sys/user.h> 35 #include <sys/systm.h> 36 #include <sys/buf.h> 37 #include <sys/ioctl.h> 38 #include <sys/tty.h> 39 #include <sys/file.h> 40 #include <sys/conf.h> 41 #include <sys/vnode.h> 42 43 #include <dev/cons.h> 44 45 static struct tty *nulltty; /* null console tty */ 46 47 cons_decl(null); 48 49 dev_type_read(nullcndev_read); 50 dev_type_ioctl(nullcndev_ioctl); 51 dev_type_tty(nullcndev_tty); 52 53 static int nullcons_newdev(struct consdev *); 54 55 const struct cdevsw nullcn_devsw = { 56 nullopen, nullclose, nullcndev_read, nullwrite, nullcndev_ioctl, 57 nullstop, nullcndev_tty, nopoll, nommap, ttykqfilter, D_TTY 58 }; 59 60 /* 61 * null console device. We need it because of the ioctl() it handles, 62 * which in particular allows control terminal allocation through 63 * TIOCSCTTY ioctl. Without the latter, system won't even boot past init(8) 64 * invocation. 65 */ 66 int 67 nullcndev_read(dev_t dev, struct uio *uio, int flag) 68 { 69 70 return EIO; 71 } 72 73 int 74 nullcndev_ioctl(dev_t dev, u_long cmd, void *data, int flag, struct lwp *l) 75 { 76 int error; 77 78 error = (*nulltty->t_linesw->l_ioctl)(nulltty, cmd, data, flag, l); 79 if (error != EPASSTHROUGH) 80 return error; 81 82 error = ttioctl(nulltty, cmd, data, flag, l); 83 if (error != EPASSTHROUGH) 84 return error; 85 86 return 0; 87 } 88 89 struct tty* 90 nullcndev_tty(dev_t dev) 91 { 92 93 return nulltty; 94 } 95 96 /* 97 * Mark console as no-op (null) console. Proper initialization is deferred 98 * to nullconsattach(). 99 */ 100 void 101 nullcnprobe(struct consdev *cn) 102 { 103 104 cn->cn_pri = CN_NULL; 105 cn->cn_dev = NODEV; 106 } 107 108 /* 109 * null console initialization. This includes allocation of a new device and 110 * a new tty. 111 */ 112 void 113 nullcninit(struct consdev *cn) 114 { 115 static struct consdev nullcn = cons_init(null); 116 117 nullcnprobe(&nullcn); 118 cn_tab = &nullcn; 119 } 120 121 /* 122 * Dumb getc() implementation. Simply blocks on call. 123 */ 124 int 125 nullcngetc(dev_t dev) 126 { 127 128 for (;;) 129 ; 130 return 0; 131 } 132 133 /* 134 * Dumb putc() implementation. 135 */ 136 void 137 nullcnputc(dev_t dev, int c) 138 { 139 140 } 141 142 /* 143 * Allocate a new console device and a tty to handle console ioctls. 144 */ 145 int 146 nullcons_newdev(struct consdev *cn) 147 { 148 int error; 149 int bmajor = -1, cmajor = -1; 150 151 if ((cn == NULL) || (cn->cn_pri != CN_NULL) || (cn->cn_dev != NODEV)) 152 return 0; 153 154 /* 155 * Attach no-op device to the device list. 156 */ 157 error = devsw_attach("nullcn", NULL, &bmajor, &nullcn_devsw, &cmajor); 158 if (error != 0) 159 return error; 160 161 /* 162 * Allocate tty (mostly to have sane ioctl()). 163 */ 164 nulltty = ttymalloc(); 165 nulltty->t_dev = makedev(cmajor, 0); 166 tty_attach(nulltty); 167 cn->cn_dev = nulltty->t_dev; 168 169 return 0; 170 } 171 172 /* 173 * Pseudo-device attach function -- it's the right time to do the rest of 174 * initialization. 175 */ 176 void 177 nullconsattach(int pdev_count) 178 { 179 180 nullcons_newdev(cn_tab); 181 } 182