1.\" Copyright (c) 1996 2.\" Julian Elischer <julian@FreeBSD.org>. All rights reserved. 3.\" 4.\" Redistribution and use in source and binary forms, with or without 5.\" modification, are permitted provided that the following conditions 6.\" are met: 7.\" 1. Redistributions of source code must retain the above copyright 8.\" notice, this list of conditions and the following disclaimer. 9.\" 10.\" 2. Redistributions in binary form must reproduce the above copyright 11.\" notice, this list of conditions and the following disclaimer in the 12.\" documentation and/or other materials provided with the distribution. 13.\" 14.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 15.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 16.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 17.\" ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 18.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 19.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 20.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 21.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 22.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 23.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 24.\" SUCH DAMAGE. 25.\" 26.\" $FreeBSD$ 27.\" 28.Dd October 10, 1998 29.Dt CD 4 30.Os 31.Sh NAME 32.Nm cd 33.Nd SCSI CD-ROM driver 34.Sh SYNOPSIS 35.Cd device cd 36.Cd "options ""CHANGER_MIN_BUSY_SECONDS=3""" 37.Cd "options ""CHANGER_MAX_BUSY_SECONDS=11"" 38.Sh DESCRIPTION 39The 40.Nm 41driver provides support for a 42.Tn SCSI 43.Tn CD-ROM 44(Compact Disc-Read Only Memory) drive. 45In an attempt to look like a regular disk, the 46.Nm 47driver synthesizes a partition table, with one partition covering the entire 48.Tn CD-ROM . 49It is possible to modify this partition table using 50.Xr disklabel 8 , 51but it will only last until the 52.Tn CD-ROM 53is unmounted. 54In general the interfaces are similar to those described by 55.Xr ad 4 56and 57.Xr da 4 . 58.Pp 59As the 60.Tn SCSI 61adapter is probed during boot, the 62.Tn SCSI 63bus is scanned for devices. 64Any devices found which answer as CDROM 65(type 5) or WORM (type 4) type devices will be `attached' to the 66.Nm 67driver. 68Prior to 69.Fx 2.1 , 70the first device found will be attached as 71.Li cd0 72the next, 73.Li cd1 , 74etc. 75Beginning in 76.Fx 2.1 77it is possible to specify what cd unit a device should 78come on line as; refer to 79.Xr scsi 4 80for details on kernel configuration. 81.Pp 82The system utility 83.Xr disklabel 8 84may be used to read the synthesized 85disk label 86structure, which will contain correct figures for the size of the 87.Tn CD-ROM 88should that information be required. 89.Sh KERNEL CONFIGURATION 90Any number of 91.Tn CD-ROM 92devices may be attached to the system regardless of system 93configuration as all resources are dynamically allocated. 94.Sh IOCTLS 95The following 96.Xr ioctl 2 97calls which apply to 98.Tn SCSI 99.Tn CD-ROM 100drives are defined 101in the header files 102.Aq Pa sys/cdio.h 103and 104.Aq Pa sys/disklabel.h . 105.Pp 106.Bl -tag -width CDIOCREADSUBCHANNEL 107.It Dv DIOCGDINFO 108.It Dv DIOCSDINFO 109.Pq Li "struct disklabel" 110Read or write the in-core copy of the disklabel for the 111drive. The disklabel is initialized with information 112read from the scsi inquiry commands, and should be the same as 113the information printed at boot. This structure is defined in 114.Xr disklabel 5 . 115.It Dv CDIOCCAPABILITY 116.Pq Li "struct ioc_capability" 117Retrieve information from the drive on what features it supports. The 118information is returned in the following structure: 119.Bd -literal -offset indent 120struct ioc_capability { 121 u_long play_function; 122#define CDDOPLAYTRK 0x00000001 123 /* Can play tracks/index */ 124#define CDDOPLAYMSF 0x00000002 125 /* Can play msf to msf */ 126#define CDDOPLAYBLOCKS 0x00000004 127 /* Can play range of blocks */ 128#define CDDOPAUSE 0x00000100 129 /* Output can be paused */ 130#define CDDORESUME 0x00000200 131 /* Output can be resumed */ 132#define CDDORESET 0x00000400 133 /* Drive can be completely reset */ 134#define CDDOSTART 0x00000800 135 /* Audio can be started */ 136#define CDDOSTOP 0x00001000 137 /* Audio can be stopped */ 138#define CDDOPITCH 0x00002000 139 /* Audio pitch can be changed */ 140 141 u_long routing_function; 142#define CDREADVOLUME 0x00000001 143 /* Volume settings can be read */ 144#define CDSETVOLUME 0x00000002 145 /* Volume settings can be set */ 146#define CDSETMONO 0x00000100 147 /* Output can be set to mono */ 148#define CDSETSTEREO 0x00000200 149 /* Output can be set to stereo (def) */ 150#define CDSETLEFT 0x00000400 151 /* Output can be set to left only */ 152#define CDSETRIGHT 0x00000800 153 /* Output can be set to right only */ 154#define CDSETMUTE 0x00001000 155 /* Output can be muted */ 156#define CDSETPATCH 0x00008000 157 /* Direct routing control allowed */ 158 159 u_long special_function; 160#define CDDOEJECT 0x00000001 161 /* The tray can be opened */ 162#define CDDOCLOSE 0x00000002 163 /* The tray can be closed */ 164#define CDDOLOCK 0x00000004 165 /* The tray can be locked */ 166#define CDREADHEADER 0x00000100 167 /* Can read Table of Contents */ 168#define CDREADENTRIES 0x00000200 169 /* Can read TOC Entries */ 170#define CDREADSUBQ 0x00000200 171 /* Can read Subchannel info */ 172#define CDREADRW 0x00000400 173 /* Can read subcodes R-W */ 174#define CDHASDEBUG 0x00004000 175 /* The tray has dynamic debugging */ 176}; 177.Ed 178.It Dv CDIOCPLAYTRACKS 179.Pq Li "struct ioc_play_track" 180Start audio playback given a track address and length. The structure 181is defined as follows: 182.Bd -literal -offset indent 183struct ioc_play_track 184{ 185 u_char start_track; 186 u_char start_index; 187 u_char end_track; 188 u_char end_index; 189}; 190.Ed 191.It Dv CDIOCPLAYBLOCKS 192.Pq Li "struct ioc_play_blocks" 193Start audio playback given a block address and length. The structure 194is defined as follows: 195.Bd -literal -offset indent 196struct ioc_play_blocks 197{ 198 int blk; 199 int len; 200}; 201.Ed 202.It Dv CDIOCPLAYMSF 203.Pq Li "struct ioc_play_msf" 204Start audio playback given a `minutes-seconds-frames' address and 205length. The structure is defined as follows: 206.Bd -literal -offset indent 207struct ioc_play_msf 208{ 209 u_char start_m; 210 u_char start_s; 211 u_char start_f; 212 u_char end_m; 213 u_char end_s; 214 u_char end_f; 215}; 216.Ed 217.It Dv CDIOCREADSUBCHANNEL 218.Pq Li "struct ioc_read_subchannel" 219Read information from the subchannel at the location specified by this 220structure: 221.Bd -literal -offset indent 222struct ioc_read_subchannel { 223 u_char address_format; 224#define CD_LBA_FORMAT 1 225#define CD_MSF_FORMAT 2 226 u_char data_format; 227#define CD_SUBQ_DATA 0 228#define CD_CURRENT_POSITION 1 229#define CD_MEDIA_CATALOG 2 230#define CD_TRACK_INFO 3 231 u_char track; 232 int data_len; 233 struct cd_sub_channel_info *data; 234}; 235.Ed 236.It Dv CDIOREADTOCHEADER 237.Pq Li "struct ioc_toc_header" 238Return summary information about the table of contents for the mounted 239.Tn CD-ROM . 240The information is returned into the following structure: 241.Bd -literal -offset indent 242struct ioc_toc_header { 243 u_short len; 244 u_char starting_track; 245 u_char ending_track; 246}; 247.Ed 248.It Dv CDIOREADTOCENTRYS 249.Pq Li "struct ioc_read_toc_entry" 250Return information from the table of contents entries mentioned. (Yes, this 251command name is misspelled.) The argument structure is defined as follows: 252.Bd -literal -offset indent 253struct ioc_read_toc_entry { 254 u_char address_format; 255 u_char starting_track; 256 u_short data_len; 257 struct cd_toc_entry *data; 258}; 259.Ed 260The requested data is written into an area of size 261.Li data_len 262and pointed to by 263.Li data . 264.It Dv CDIOCSETPATCH 265.Pq Li "struct ioc_patch" 266Attach various audio channels to various output channels. The 267argument structure is defined thusly: 268.Bd -literal -offset indent 269struct ioc_patch { 270 u_char patch[4]; 271 /* one for each channel */ 272}; 273.Ed 274.It Dv CDIOCGETVOL 275.It Dv CDIOCSETVOL 276.Pq Li "struct ioc_vol" 277Get (set) information about the volume settings of the output channels. The 278argument structure is as follows: 279.Bd -literal -offset indent 280struct ioc_vol 281{ 282 u_char vol[4]; 283 /* one for each channel */ 284}; 285.Ed 286.It Dv CDIOCSETMONO 287Patch all output channels to all source channels. 288.It Dv CDIOCSETSTEREO 289Patch left source channel to the left output channel and the right 290source channel to the right output channel. 291.It Dv CDIOCSETMUTE 292Mute output without changing the volume settings. 293.It Dv CDIOCSETLEFT 294.It Dv CDIOCSETRIGHT 295Attach both output channels to the left (right) source channel. 296.It Dv CDIOCSETDEBUG 297.It Dv CDIOCCLRDEBUG 298Turn on (off) debugging for the appropriate device. 299.It Dv CDIOCPAUSE 300.It Dv CDIOCRESUME 301Pause (resume) audio play, without resetting the location of the read-head. 302.It Dv CDIOCRESET 303Reset the drive. 304.It Dv CDIOCSTART 305.It Dv CDIOCSTOP 306Tell the drive to spin-up (-down) the 307.Tn CD-ROM . 308.It Dv CDIOCALLOW 309.It Dv CDIOCPREVENT 310Tell the drive to allow (prevent) manual ejection of the 311.Tn CD-ROM 312disc. Not all drives support this feature. 313.It Dv CDIOCEJECT 314Eject the 315.Tn CD-ROM . 316.It Dv CDIOCCLOSE 317Tell the drive to close its door and load the media. Not all drives 318support this feature. 319.It Dv CDIOCPITCH 320.Pq Li "struct ioc_pitch" 321For drives that support it, this command instructs the drive to play 322the audio at a faster or slower rate than normal. Values of 323.Li speed 324between -32767 and -1 result in slower playback; a zero value 325indicates normal speed; and values from 1 to 32767 give faster 326playback. Drives with less than 16 bits of resolution will silently 327ignore less-significant bits. The structure is defined thusly: 328.Bd -literal -offset indent 329struct ioc_pitch 330{ 331 short speed; 332}; 333.Ed 334.El 335.Sh NOTES 336When a 337.Tn CD-ROM 338is changed in a drive controlled by the 339.Nm 340driver, then the act of changing the media will invalidate the 341disklabel and information held within the kernel. To stop corruption, 342all accesses to the device will be discarded until there are no more 343open file descriptors referencing the device. During this period, all 344new open attempts will be rejected. When no more open file descriptors 345reference the device, the first next open will load a new set of 346parameters (including disklabel) for the drive. 347.Pp 348The audio code in the 349.Nm 350driver only support 351.Tn SCSI-2 352standard audio commands. 353Because many 354.Tn CD-ROM 355manufacturers have not followed the standard, there are many 356.Tn CD-ROM 357drives for which audio will not work. 358Some work is planned to support 359some of the more common `broken' 360.Tn CD-ROM 361drives; however, this is not yet under way. 362.Sh CHANGER OPERATION 363This driver has built-in support for LUN-based CD changers. A LUN-based CD 364changer is a drive that can hold two or more CDs, but only has one CD 365player mechanism. Each CD in the drive shows up as a separate logical unit 366on the 367.Tn SCSI 368bus. The 369.Nm 370driver automatically recognizes LUN-based changers, and routes commands for 371changers through an internal scheduler. The scheduler prevents changer 372"thrashing", which is caused by sending commands to different LUNs in the 373changer at the same time. 374.Pp 375The scheduler honors minimum and maximum time 376quanta that the driver will spend on a particular LUN. The minimum time 377is the guaranteed minimum amount of time that the driver will spend on a 378given LUN, even if there is no outstanding I/O for that LUN. The maximum 379time is the maximum amount of time the changer will spend on a LUN if there 380is outstanding I/O for another LUN. If there is no outstanding I/O for 381another LUN, the driver will allow indefinite access to a given LUN. 382.Pp 383The minimum and maximum time quanta are configurable via kernel options and 384also via sysctl variables. The kernel options are: 385.Pp 386.Bl -item -compact 387.It 388.Cd "options ""CHANGER_MIN_BUSY_SECONDS=3""" 389.It 390.Cd "options ""CHANGER_MAX_BUSY_SECONDS=11""" 391.El 392.Pp 393The sysctl variables are: 394.Pp 395.Bl -item -compact 396.It 397.Va kern.cam.cd.changer.min_busy_seconds 398.It 399.Va kern.cam.cd.changer.max_busy_seconds 400.El 401.Pp 402It is suggested that the user try experimenting with the minimum and 403maximum timeouts via the sysctl variables to arrive at the proper values 404for your changer. Once you have settled on the proper timeouts for your 405changer, you can then put them in your kernel config file. 406.Pp 407If your system does have a LUN-based changer, you may notice that the 408probe messages for the various LUNs of the changer will continue to appear 409while the boot process is going on. This is normal, and is caused by the 410changer scheduling code. 411.Sh FILES 412.Bl -tag -width /dev/cd[0-9][a-h] -compact 413.It Pa /dev/cd[0-9][a-h] 414raw mode 415.Tn CD-ROM 416devices 417.El 418.Sh DIAGNOSTICS 419None. 420.Sh SEE ALSO 421.Xr da 4 , 422.Xr scsi 4 , 423.Xr disklabel 5 , 424.Xr disklabel 8 , 425.Xr cd 9 426.Sh BUGS 427The names of the structures used for the third argument to 428.Fn ioctl 429were poorly chosen, and a number of spelling errors have survived in 430the names of the 431.Fn ioctl 432commands. 433.Pp 434There is no mechanism currently to set different minimum and maximum 435timeouts for different CD changers; the timeout values set by the kernel 436options or the sysctl variables apply to all LUN-based CD changers in the 437system. It is possible to implement such support, but the sysctl 438implementation at least would be rather inelegant, because of the current 439inability of the sysctl code to handle the addition of nodes after compile 440time. Thus, it would take one dynamically sized sysctl variable and a 441userland utility to get/set the timeout values. Implementation of separate 442timeouts for different CD devices in the kernel config file would likely 443require modification of 444.Xr config 8 445to support the two timeouts when hardwiring 446.Nm 447devices. 448.Sh HISTORY 449This 450.Nm 451driver is based upon the 452.Nm 453driver written by Julian Elischer, which appeared in 454.Bx 386 0.1 . 455The 456CAM version of the 457.Nm 458driver was written by Kenneth Merry and first appeared in 459.Fx 3.0 . 460