aztcd

《嵌入式系统设计与实例开发实验教材二源码》Linux内核移植与编译实验

$Id: README.aztcd,v 2.60 1997/11/29 09:51:25 root Exp root $
          Readme-File /usr/src/Documentation/cdrom/aztcd
           			for 
	     AZTECH CD-ROM CDA268-01A, ORCHID CD-3110,
      OKANO/WEARNES CDD110, CONRAD TXC, CyCDROM CR520, CR540
                           CD-ROM Drives 
                       Version 2.6 and newer
                   (for other drives see 6.-8.)

NOTE: THIS DRIVER WILL WORK WITH THE CD-ROM DRIVES LISTED, WHICH HAVE
      A PROPRIETARY INTERFACE (implemented on a sound card or on an
      ISA-AT-bus card). 
      IT WILL DEFINITELY NOT WORK WITH CD-ROM DRIVES WITH *IDE*-INTERFACE,
      such as the Aztech CDA269-031SE !!! (The only known exceptions are
      'faked' IDE drives like the CyCDROM CR520ie which work with aztcd
      under certain conditions, see 7.). IF YOU'RE USING A CD-ROM DRIVE
      WITH IDE-INTERFACE, SOMETIMES ALSO CALLED ATAPI-COMPATIBLE, PLEASE 
      USE THE ide-cd.c DRIVER, WRITTEN BY MARK LORD AND SCOTT SNYDER !
      THE STANDARD-KERNEL 1.2.x NOW ALSO SUPPORTS IDE-CDROM-DRIVES, SEE THE
      HARDDISK (!) SECTION OF make config, WHEN COMPILING A NEW KERNEL!!!
----------------------------------------------------------------------------

Contents of this file:
                         1.  NOTE
                         2.  INSTALLATION
                         3.  CONFIGURING YOUR KERNEL
                         4.  RECOMPILING YOUR KERNEL
                         4.1   AZTCD AS A RUN-TIME LOADABLE MODULE
                         4.2   CDROM CONNECTED TO A SOUNDCARD
                         5.  KNOWN PROBLEMS, FUTURE DEVELOPMENTS
			 5.1   MULTISESSION SUPPORT
			 5.2   STATUS RECOGNITION
			 5.3   DOSEMU's CDROM SUPPORT
                         6.  BUG REPORTS
                         7.  OTHER DRIVES
                         8.  IF YOU DON'T SUCCEED ... DEBUGGING  
                         9.  TECHNICAL HISTORY OF THE DRIVER
                        10.  ACKNOWLEDGMENTS
                        11.  PROGRAMMING ADD ONS: CDPLAY.C
                        APPENDIX: Source code of cdplay.c
----------------------------------------------------------------------------

1. NOTE 
This software has been successfully in alpha and beta test and is part of
the standard kernel since kernel 1.1.8x since December 1994. It works with
AZTECH CDA268-01A, ORCHID CDS-3110, ORCHID/WEARNES CDD110 and CONRAD TXC 
(Nr.99 31 23 -series 04) and has proven to be stable with kernel 
versions 1.0.9 and newer. But with any software there still may be bugs in it. 
So if you encounter problems, you are invited to help us improve this software. 
Please send me a detailed bug report (see chapter BUG REPORTS). You are also 
invited in helping us to increase the number of drives, which are supported.

Please read the README-files carefully and always keep a backup copy of your 
old kernel, in order to reboot if something goes wrong!

2. INSTALLATION
The driver consists of a header file 'aztcd.h', which normally should reside 
in /usr/src/linux/drivers/cdrom and the source code 'aztcd.c', which normally 
resides in the same place. It uses /dev/aztcd (/dev/aztcd0 in some distri-
butions), which must be a valid block device with major number 29 and reside 
in directory /dev. To mount a CD-ROM, your kernel needs to have the ISO9660-
filesystem support included.

PLEASE NOTE: aztcd.c has been developed in parallel to the linux kernel,
which had and is having many major and minor changes which are not backward
compatible. Quite definitely aztcd.c version 1.80 and newer will NOT work
in kernels older than 1.3.33. So please always use the most recent version
of aztcd.c with the appropriate linux-kernel.

3.  CONFIGURING YOUR KERNEL
If your kernel is already configured for using the AZTECH driver you will
see the following message while Linux boots:
    Aztech CD-ROM Init: DriverVersion=<version number> BaseAddress=<baseaddress>
    Aztech CD-ROM Init: FirmwareVersion=<firmware version id of your I/O-card>>>
    Aztech CD-ROM Init: <drive type> detected
    Aztech CD-ROM Init: End
If the message looks different and you are sure to have a supported drive,
it may have a different base address. The Aztech driver does look for the 
CD-ROM drive at the base address specified in aztcd.h at compile time. This 
address can be overwritten by boot parameter aztcd=....You should reboot and 
start Linux with boot parameter aztcd=<base address>, e.g. aztcd=0x320. If 
you do not know the base address, start your PC with DOS and look at the boot 
message of your CD-ROM's DOS driver. If that still does not help, use boot
parameter aztcd=<base address>,0x79 , this tells aztcd to try a little harder.
aztcd may be configured to use autoprobing the base address by recompiling
it (see chapter 4.).

If the message looks correct, as user 'root' you should be able to mount the 
drive by
          mount -t iso9660 -r /dev/aztcd0 /mnt
and use it as any other filesystem. (If this does not work, check if
/dev/aztcd0 and /mnt do exist and create them, if necessary by doing
      mknod /dev/aztcd0 b 29 0
      mkdir /mnt                       

If you still get a different message while Linux boots or when you get the 
message, that the ISO9660-filesystem is not supported by your kernel, when
you try to mount the CD-ROM drive, you have to recompile your kernel.

If you do *not* have an Aztech/Orchid/Okano/Wearnes/TXC drive and want to 
bypass drive detection during Linux boot up, start with boot parameter aztcd=0.

Most distributions nowadays do contain a boot disk image containing aztcd.
Please note, that this driver will not work with IDE/ATAPI drives! With these 
you must use ide-cd.c instead.

4. RECOMPILING YOUR KERNEL
If your kernel is not yet configured for the AZTECH driver and the ISO9660-
filesystem, you have to recompile your kernel: 

- Edit aztcd.h to set the I/O-address to your I/O-Base address (AZT_BASE_ADDR), 
  the driver does not use interrupts or DMA, so if you are using an AZTECH
  CD268, an ORCHID CD-3110 or ORCHID/WEARNES CDD110 that's the only item you 
  have to set up. If you have a soundcard, read chapter 4.2.
  Users of other drives should read chapter OTHER DRIVES of this file.
  You also can configure that address by kernel boot parameter aztcd=... 
- aztcd may be configured to use autoprobing the base address by setting
  AZT_BASE_ADDR to '-1'. In that case aztcd probes the addresses listed 
  under AZT_BASE_AUTO. But please remember, that autoprobing always may 
  incorrectly influence other hardware components too!
- There are some other points, which may be configured, e.g. auto-eject the
  CD when unmounting a drive, tray locking etc., see aztcd.h for details.
- If you're using a linux kernel version prior to 2.1.0, in aztcd.h
  uncomment the line '#define AZT_KERNEL_PRIOR_2_1'
- Build a new kernel, configure it for 'Aztech/Orchid/Okano/Wearnes support' 
  (if you want aztcd to be part of the kernel). Do not configure it for
  'Aztech... support', if you want to use aztcd as a run time loadable module. 
  But in any case you must have the ISO9660-filesystem included in your
  kernel.
- Activate the new kernel, normally this is done by running LILO (don't for-
  get to configure it before and to keep a copy of your old kernel in case
  something goes wrong!).
- Reboot
- If you've included aztcd in your kernel, you now should see during boot 
  some messages like
    Aztech CD-ROM Init: DriverVersion=<version number> BaseAddress=<baseaddress>
    Aztech CD-ROM Init: FirmwareVersion=<firmware version id of your I/O-card>
    Aztech CD-ROM Init: <drive type> detected
    Aztech CD-ROM Init: End
- If you have not included aztcd in your kernel, but want to load aztcd as a 
  run time loadable module see 4.1. 
- If the message looks correct, as user 'root' you should be able to mount 
  the drive by
          mount -t iso9660 -r /dev/aztcd0 /mnt
  and use it as any other filesystem. (If this does not work, check if
  /dev/aztcd0 and /mnt do exist and create them, if necessary by doing
      mknod /dev/aztcd0 b 29 0
      mkdir /mnt                       
- If this still does not help, see chapters OTHER DRIVES and DEBUGGING.

4.1 AZTCD AS A RUN-TIME LOADABLE MODULE
If you do not need aztcd permanently, you can also load and remove the driver
during runtime via insmod and rmmod. To build aztcd as a loadable module you 
must configure your kernel for AZTECH module support (answer 'm' when con-
figuring the kernel). Anyhow, you may run into problems, if the version of 
your boot kernel is not the same than the source kernel version, from which 
you create the modules. So rebuild your kernel, if necessary. 

Now edit the base address of your AZTECH interface card in
/usr/src/linux/drivers/cdrom/aztcd.h to the appropriate value. 
aztcd may be configured to use autoprobing the base address by setting
AZT_BASE_ADDR to '-1'. In that case aztcd probes the addresses listed 
under AZT_BASE_AUTO. But please remember, that autoprobing always may 
incorrectly influence other hardware components too!
There are also some special features which may be configured, e.g. 
auto-eject a CD when unmounting the drive etc; see aztcd.h for details. 
Then change to /usr/src/linux and do a 
                    make modules  
	            make modules_install
After that you can run-time load the driver via
                    insmod /lib/modules/X.X.X/misc/aztcd.o
and remove it via   rmmod  aztcd.
If you did not set the correct base address in aztcd.h, you can also supply the
base address when loading the driver via
                    insmod /lib/modules/X.X.X/misc/aztcd.o aztcd=<base address>
Again specifying aztcd=-1 will cause autoprobing.
If you do not have the iso9660-filesystem in your boot kernel, you also have
to load it before you can mount the CDROM:
                    insmod /lib/modules/X.X.X/fs/isofs.o
The mount procedure works as described in 4. above.
(In all commands 'X.X.X' is the current linux kernel version number. For details
see file modules.txt in /usr/src/linux/Documentation)

4.2 CDROM CONNECTED TO A SOUNDCARD
Most soundcards do have a bus interface to the CDROM-drive. In many cases
this soundcard needs to be configured, before the CDROM can be used. This
configuration procedure consists of writing some kind of initialization
data to the soundcard registers. The AZTECH-CDROM driver in the moment does
only support one type of soundcard (SoundWave32). Users of other soundcards
should try to boot DOS first and let their DOS drivers initialize the
soundcard and CDROM, then warm boot (or use loadlin) their PC to start
Linux.
Support for the CDROM-interface of SoundWave32-soundcards is directly
implemented in the AZTECH driver. Please edit linux/drivers/cdrom/aztdc.h,
uncomment line '#define AZT_SW32' and set the appropriate value for
AZT_BASE_ADDR and AZT_SW32_BASE_ADDR. This support was tested with an Orchid
CDS-3110 connected to a SoundWave32.
If you want your soundcard to be supported, find out, how it needs to be
configured and mail me (see 6.) the appropriate information. 

5. KNOWN PROBLEMS, FUTURE DEVELOPMENTS
5.1 MULTISESSION SUPPORT
Multisession support for CD's still is a myth. I implemented and tested a basic
support for multisession and XA CDs, but I still have not enough CDs and appli-
cations to test it rigorously. So if you'd like to help me, please contact me
(Email address see below). As of version 1.4 and newer you can enable the 
multisession support in aztcd.h by setting AZT_MULTISESSION to 1. Doing so 
will cause the ISO9660-filesystem to deal with multisession CDs, ie. redirect 
requests to the Table of Contents (TOC) information from the last session, 
which contains the info of all previous sessions etc.. If you do set 
AZT_MULTISESSION to 0, you can use multisession CDs anyway. In that case the 
drive's firmware will do automatic redirection. For the ISO9660-filesystem any 
multisession CD  will then look like a 'normal' single session CD. But never-
theless the data of all sessions are viewable and accessible. So with practical-
ly all real world applications you won't notice the difference. But as future
applications may make use of advanced multisession features, I've started to
implement the interface for the ISO9660 multisession interface via ioctl
CDROMMULTISESSION.

5.2 STATUS RECOGNITION
The drive status recognition does not work correctly in all cases. Changing
a disk or having the door open, when a drive is already mounted, is detected 
by the Aztech driver itself, but nevertheless causes multiple read attempts
by the different layers of the ISO9660-filesystem driver, which finally timeout,
so you have to wait quite a little... But isn't it bad style to change a disk 
in a mounted drive, anyhow ?!

The driver uses busy wait in most cases for the drive handshake (macros
STEN_LOW and DTEN_LOW). I tested with a 486/DX2 at 66MHz and a Pentium at
60MHz and 90MHz. Whenever you use a much faster machine you are likely to get 
timeout messages. In that case edit aztcd.h and increase the timeout value 
AZT_TIMEOUT. 

For some 'slow' drive commands I implemented waiting with a timer waitqueue
(macro STEN_LOW_WAIT). If you get this timeout message, you may also edit
aztcd.h and increase the timeout value AZT_STATUS_DELAY. The waitqueue has
shown to be a little critical. If you get kernel panic messages, edit aztcd.c
and substitute STEN_LOW_WAIT by STEN_LOW. Busy waiting with STEN_LOW is more
stable, but also causes CPU overhead.

5.3 DOSEMU's CD-ROM SUPPORT
With release 1.20 aztcd was modified to allow access to CD-ROMS when running
under dosemu-0.60.0 aztcd-versions before 1.20 are most likely to crash
Linux, when a CD-ROM is accessed under dosemu. This problem has partly been
fixed, but still when accessing a directory for the first time the system
might hang for some 30sec. So be patient, when using dosemu's CD-ROM support
in combination with aztcd :-) ! 
This problem has now (July 1995) been fixed by a modification to dosemu's
CD-ROM driver. The new version came with dosemu-0.60.2, see dosemu's
README.CDROM.

6. BUG REPORTS
Please send detailed bug reports and bug fixes via EMail to

        [e-mail]

Please include a description of your CD-ROM drive type and interface card, 
the exact firmware message during Linux bootup, the version number of the 
AZTECH-CDROM-driver and the Linux kernel version. Also a description of your 
system's other hardware could be of interest, especially microprocessor type, 
clock frequency, other interface cards such as soundcards, ethernet adapter, 
game cards etc..

I will try to collect the reports and make the necessary modifications from 
time to time. I may also come back to you directly with some bug fixes and 
ask you to do further testing and debugging.

Editors of CD-ROMs are invited to send a 'cooperation' copy of their
CD-ROMs to the volunteers, who provided the CD-ROM support for Linux. My
snail mail address for such 'stuff' is
           Prof. Dr. W. Zimmermann
           Fachhochschule fuer Technik Esslingen
           Fachbereich IT
           Flandernstrasse 101
           D-73732 Esslingen