1 /* $NetBSD: nullcons_subr.c,v 1.10 2009/11/23 02:13:45 rmind 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 1.10 2009/11/23 02:13:45 rmind 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 nullopen, nullclose, nullcndev_read, nullwrite, nullcndev_ioctl, 56 nullstop, nullcndev_tty, nopoll, nommap, ttykqfilter, D_TTY 57 }; 58 59 /* 60 * null console device. We need it because of the ioctl() it handles, 61 * which in particular allows control terminal allocation through 62 * TIOCSCTTY ioctl. Without the latter, system won't even boot past init(8) 63 * invocation. 64 */ 65 int 66 nullcndev_read(dev_t dev, struct uio *uio, int flag) 67 { 68 69 return EIO; 70 } 71 72 int 73 nullcndev_ioctl(dev_t dev, u_long cmd, void *data, int flag, struct lwp *l) 74 { 75 int error; 76 77 error = (*nulltty->t_linesw->l_ioctl)(nulltty, cmd, data, flag, l); 78 if (error != EPASSTHROUGH) 79 return error; 80 81 error = ttioctl(nulltty, cmd, data, flag, l); 82 if (error != EPASSTHROUGH) 83 return error; 84 85 return 0; 86 } 87 88 struct tty* 89 nullcndev_tty(dev_t dev) 90 { 91 92 return nulltty; 93 } 94 95 /* 96 * Mark console as no-op (null) console. Proper initialization is deferred 97 * to nullconsattach(). 98 */ 99 void 100 nullcnprobe(struct consdev *cn) 101 { 102 103 cn->cn_pri = CN_NULL; 104 cn->cn_dev = NODEV; 105 } 106 107 /* 108 * null console initialization. This includes allocation of a new device and 109 * a new tty. 110 */ 111 void 112 nullcninit(struct consdev *cn) 113 { 114 static struct consdev nullcn = cons_init(null); 115 116 nullcnprobe(&nullcn); 117 cn_tab = &nullcn; 118 } 119 120 /* 121 * Dumb getc() implementation. Simply blocks on call. 122 */ 123 int 124 nullcngetc(dev_t dev) 125 { 126 127 for (;;) 128 ; 129 return 0; 130 } 131 132 /* 133 * Dumb putc() implementation. 134 */ 135 void 136 nullcnputc(dev_t dev, int c) 137 { 138 139 } 140 141 /* 142 * Allocate a new console device and a tty to handle console ioctls. 143 */ 144 int 145 nullcons_newdev(struct consdev *cn) 146 { 147 int error; 148 int bmajor = -1, cmajor = -1; 149 150 if ((cn == NULL) || (cn->cn_pri != CN_NULL) || (cn->cn_dev != NODEV)) 151 return 0; 152 153 /* 154 * Attach no-op device to the device list. 155 */ 156 error = devsw_attach("nullcn", NULL, &bmajor, &nullcn_devsw, &cmajor); 157 if (error != 0) 158 return error; 159 160 /* 161 * Allocate tty (mostly to have sane ioctl()). 162 */ 163 nulltty = ttymalloc(); 164 nulltty->t_dev = makedev(cmajor, 0); 165 tty_attach(nulltty); 166 cn->cn_dev = nulltty->t_dev; 167 168 return 0; 169 } 170 171 /* 172 * Pseudo-device attach function -- it's the right time to do the rest of 173 * initialization. 174 */ 175 void 176 nullconsattach(int pdev_count) 177 { 178 179 nullcons_newdev(cn_tab); 180 } 181