Tips for using cdu31a.c, the driver for Sony CDU-31A and CDU-33A CDROM
   drives.
  
   Corey Minyard (minyard@wf-rch.cirr.com)
  
   Colossians 3:17
  
   The Sony interface device driver handles Sony interface CDROM
   drives and provides a complete block-level interface as well as an
   ioctl() interface compatible with the Sun (as specified in
   include/linux/cdrom.h).  With this interface, CDROMs can be
   accessed and standard audio CDs can be played back normally.
  
   WARNING - 	All autoprobes have been removed from the driver.
  		You MUST configure the CDU31A via a LILO config
  		at boot time or in lilo.conf.  I have the
  		following in my lilo.conf:
  
                  append="cdu31a=0x1f88,0,PAS"
  
  		The first number is the I/O base address of the
  		card.  The second is the interrupt (0 means none).
  		The third should be "PAS" if on a Pro-Audio
  		spectrum, or nothing if on something else.
  
   This interface is (unfortunately) a polled interface.  This is
   because most Sony interfaces are set up with DMA and interrupts
   disables.  Some (like mine) do not even have the capability to
   handle interrupts or DMA.  For this reason you will see a lot of
   the following:
  
     retry_count = jiffies+ SONY_JIFFIES_TIMEOUT;
     while ((retry_count > jiffies) && (! <some condition to wait for))
     {
        while (handle_sony_cd_attention())
           ;
  
        sony_sleep();
     }
     if (the condition not met)
     {
        return an error;
     }
  
   This ugly hack waits for something to happen, sleeping a little
   between every try.  it also handles attentions, which are
   asynchronous events from the drive informing the driver that a disk
   has been inserted, removed, etc.
  
   NEWS FLASH - The driver now supports interrupts but they are
   turned off by default.  Use of interrupts is highly encouraged, it
   cuts CPU usage down to a reasonable level.  I had DMA in for a while
   but PC DMA is just too slow.  Better to just insb() it.
  
   One thing about these drives: They talk in MSF (Minute Second Frame) format.
   There are 75 frames a second, 60 seconds a minute, and up to 75 minutes on a
   disk.  The funny thing is that these are sent to the drive in BCD, but the
   interface wants to see them in decimal.  A lot of conversion goes on.
  
   DRIVER SPECIAL FEATURES
   -----------------------
  
   This section describes features beyond the normal audio and CD-ROM
   functions of the drive.
  
   2048 byte buffer mode
  
   If a disk is mounted with -o block=2048, data is copied straight
   from the drive data port to the buffer.  Otherwise, the readahead
   buffer must be involved to hold the other 1K of data when a 1K
   block operation is done.  Note that with 2048 byte blocks you
   cannot execute files from the CD.
  
   XA compatibility
  
   The driver should support XA disks for both the CDU31A and CDU33A.
   It does this transparently, the using program doesn't need to set it.
  
   Multi-Session
  
   A multi-session disk looks just like a normal disk to the user.
   Just mount one normally, and all the data should be there.
   A special thanks to Koen for help with this!
   
   Raw sector I/O
  
   Using the CDROMREADAUDIO it is possible to read raw audio and data
   tracks.  Both operations return 2352 bytes per sector.  On the data
   tracks, the first 12 bytes is not returned by the drive and the value
   of that data is indeterminate.
  
  
    Copyright (C) 1993  Corey Minyard
  
    This program is free software; you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
    the Free Software Foundation; either version 2 of the License, or
    (at your option) any later version.
  
    This program is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU General Public License for more details.
  
    You should have received a copy of the GNU General Public License
    along with this program; if not, write to the Free Software
    Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
  
  /

/*
  
   Setting up the Sony CDU31A/CDU33A drive interface card.  If
   You have another card, you are on your own.
   
        +----------+-----------------+----------------------+
        |  JP1     |  34 Pin Conn    |                      |
        |  JP2     +-----------------+                      |
        |  JP3                                              |
        |  JP4                                              |
        |                                                   +--+
        |                                                   |  +-+
        |                                                   |  | |  External
        |                                                   |  | |  Connector
        |                                                   |  | |
        |                                                   |  +-+
        |                                                   +--+
        |                                                   |
        |                                          +--------+
        |                                          |
        +------------------------------------------+
   
      JP1 sets the Base Address, using the following settings:
   
        Address         Pin 1           Pin 2
        -------         -----           -----
        0x320           Short           Short
        0x330           Short           Open
        0x340           Open            Short
        0x360           Open            Open
   
      JP2 and JP3 configure the DMA channel; they must be set the same.
   
        DMA             Pin 1           Pin 2           Pin 3
        ---             -----           -----           -----
        1               On              Off             On
        2               Off             On              Off
        3               Off             Off             On
   
      JP4 Configures the IRQ:
   
        IRQ     Pin 1           Pin 2           Pin 3           Pin 4
        ---     -----           -----           -----           -----
        3       Off             Off             On              Off
        4       Off             Off*            Off             On
        5       On              Off             Off             Off
        6       Off             On              Off             Off
   
                  The documentation states to set this for interrupt
                  4, but I think that is a mistake.