1 /*- 2 * Copyright (c) 2000 Mark R. V. Murray & Jeroen C. van Gelderen 3 * All rights reserved. 4 * 5 * Redistribution and use in source and binary forms, with or without 6 * modification, are permitted provided that the following conditions 7 * are met: 8 * 1. Redistributions of source code must retain the above copyright 9 * notice, this list of conditions and the following disclaimer 10 * in this position and unchanged. 11 * 2. Redistributions in binary form must reproduce the above copyright 12 * notice, this list of conditions and the following disclaimer in the 13 * documentation and/or other materials provided with the distribution. 14 * 15 * THIS SOFTWARE IS PROVIDED BY THE AUTHORS ``AS IS'' AND ANY EXPRESS OR 16 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 17 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 18 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 19 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 20 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 21 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 22 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 23 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 24 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 25 * 26 * $FreeBSD$ 27 */ 28 29 #include <sys/param.h> 30 #include <sys/systm.h> 31 #include <sys/conf.h> 32 #include <sys/uio.h> 33 #include <sys/kernel.h> 34 #include <sys/malloc.h> 35 #include <sys/module.h> 36 #include <sys/disk.h> 37 #include <sys/bus.h> 38 #include <machine/bus.h> 39 #include <machine/resource.h> 40 #include <sys/rman.h> 41 42 /* For use with destroy_dev(9). */ 43 static dev_t null_dev; 44 static dev_t zero_dev; 45 46 static d_write_t null_write; 47 static d_ioctl_t null_ioctl; 48 static d_read_t zero_read; 49 50 #define CDEV_MAJOR 2 51 #define NULL_MINOR 2 52 #define ZERO_MINOR 12 53 54 static struct cdevsw null_cdevsw = { 55 /* open */ (d_open_t *)nullop, 56 /* close */ (d_close_t *)nullop, 57 /* read */ (d_read_t *)nullop, 58 /* write */ null_write, 59 /* ioctl */ null_ioctl, 60 /* poll */ nopoll, 61 /* mmap */ nommap, 62 /* strategy */ nostrategy, 63 /* name */ "null", 64 /* maj */ CDEV_MAJOR, 65 /* dump */ nodump, 66 /* psize */ nopsize, 67 /* flags */ 0, 68 }; 69 70 static struct cdevsw zero_cdevsw = { 71 /* open */ (d_open_t *)nullop, 72 /* close */ (d_close_t *)nullop, 73 /* read */ zero_read, 74 /* write */ null_write, 75 /* ioctl */ noioctl, 76 /* poll */ nopoll, 77 /* mmap */ nommap, 78 /* strategy */ nostrategy, 79 /* name */ "zero", 80 /* maj */ CDEV_MAJOR, 81 /* dump */ nodump, 82 /* psize */ nopsize, 83 /* flags */ D_MMAP_ANON, 84 }; 85 86 static void *zbuf; 87 88 static int 89 null_write(dev_t dev, struct uio *uio, int flag) 90 { 91 uio->uio_resid = 0; 92 return 0; 93 } 94 95 static int 96 null_ioctl(dev_t dev, u_long cmd, caddr_t data, int fflag, struct thread *td) 97 { 98 int error; 99 100 if (cmd != DIOCSKERNELDUMP) 101 return (noioctl(dev, cmd, data, fflag, td)); 102 error = suser(td); 103 if (error) 104 return (error); 105 return (set_dumper(NULL)); 106 } 107 108 109 static int 110 zero_read(dev_t dev, struct uio *uio, int flag) 111 { 112 u_int c; 113 int error = 0; 114 115 while (uio->uio_resid > 0 && error == 0) { 116 c = min(uio->uio_resid, PAGE_SIZE); 117 error = uiomove(zbuf, c, uio); 118 } 119 return error; 120 } 121 122 static int 123 null_modevent(module_t mod, int type, void *data) 124 { 125 switch(type) { 126 case MOD_LOAD: 127 if (bootverbose) 128 printf("null: <null device, zero device>\n"); 129 zbuf = (void *)malloc(PAGE_SIZE, M_TEMP, M_WAITOK | M_ZERO); 130 zero_dev = make_dev(&zero_cdevsw, ZERO_MINOR, UID_ROOT, 131 GID_WHEEL, 0666, "zero"); 132 null_dev = make_dev(&null_cdevsw, NULL_MINOR, UID_ROOT, 133 GID_WHEEL, 0666, "null"); 134 return 0; 135 136 case MOD_UNLOAD: 137 destroy_dev(null_dev); 138 destroy_dev(zero_dev); 139 free(zbuf, M_TEMP); 140 return 0; 141 142 case MOD_SHUTDOWN: 143 return 0; 144 145 default: 146 return EOPNOTSUPP; 147 } 148 } 149 150 DEV_MODULE(null, null_modevent, NULL); 151