This is a new version of my driver for the NEC CDR-260 cd-rom drive.
Major changes since the last release are:

  - The driver is now structured as a loadable kernel module.

  - It now should work on a wider variety of hardware configurations,
    including those where the drive is on the second IDE controller.

  - The driver should now properly detect media changes.  The bug in
    the previous version which caused the first operation after a
    media change to fail should be fixed.

  - The name has changed to something more descriptive, and the
    default major device number has changed to avoid a conflict with
    atdisk2.

No audio functions are supported, and probably won't be for a while
unless i can turn up some actual technical documentation on this
device.

Not all possible hardware configurations have been tested.
So far, configurations which i've heard that work include:

  - cdrom as slave device on first IDE bus with a hd as master.
  - cdrom by itself as master on second IDE bus.

Installation instructions:

  - If you have anything on your hard drive which you'd mind losing,
    it would be a good idea to make a backup before starting.  I have
    never seen any instances in which this driver screws up a
    filesystem; however, it has every opportunity to do so, and i'm
    not making any promises...

  - Since the driver is now a loadable module, you'll need to have the
    module utilities before you can do anything with it.  A copy of
    may be found in sunsite.unc.edu:/pub/Linux/kernel/modules.tar.gz.
    If you don't already have this package, fetch it and install it on
    your machine.

  - There are a couple kernel patches which are required to add some
    hooks needed by the driver.  These patches were made against
    version 1.1.50.

    If you have a kernel version of at least 1.1.49, then you should
    apply the three patches in hd.c.diffs, ksyms.c.diffs, and
    config.in.diffs.  You should be able to do this by setting your
    default directory to the top of the kernel source tree and doing,
    e.g., `patch -p0 <hd.c.diffs'.  If you have an older version, look
    at the notes below (some of these files have been changed by
    recent kernel patches in ways that makes it difficult to come up
    with a single set of patches...).

      arch/i386/config.in: In kernel versions 1.1.44 and earlier,
                           this file was in the top directory of the source
                           tree rather than in arch/i386.

      drivers/block/blk.h: If you have 1.1.46 or earlier, apply the patch
                           in the file blk.h.diffs-46.  For versions 1.1.47
                           and later, no patches to this file are
			   required.

      drivers/block/hd.c:  Apply the patch in hd.c.diffs.

      kernel/ksyms.c:      For kernel versions 1.1.48 and earlier, apply
                           the patch in ksyms.c.diffs-48.  Otherwise,
                           apply the patch in ksyms.c.diffs.

    If your cdrom drive is on a second IDE bus along with a hard drive
    and you are using the atdisk2 patches to get at the hard drive,
    try applying the hd.c patch to hd1.c instead.  (Warning: as far as
    i know, this configuration has not been tested.)

  - Do a `make config' and answer yes to the question about
    NEC CDR-260 support.

  - Rebuild and install the kernel as usual.  Boot the system with the
    new kernel.

  - Go back to the directory containing this package.  Look at the
    start of the Makefile, and check that the path to the kernel
    source is correct for your system.  Then look at the hardware
    configuration options near the start of nec260.c.  These are a
    collection of integer variables which tell the driver what
    hardware configuration to expect.  These values can be set
    dynamically when you load the driver, but it may be safer to
    change the compiled-in defaults.  The configuration variables
    their and defaults are:

      nec260_major = 26    Sets the major device number which the driver
                           will attempt to use.

      nec260_base = 0x1f0  The first I/O address for the IDE adapter.
                           The second IDE adapter should be at 0x170.
                           If you're not sure of the proper address, you
                           can probably find it in your mess-dos config.sys
                           (assuming the drive works under mess-dos).

      nec260_irq  = 14     The IRQ level used by the adapter.

      nec260_master = 0    Set this to 1 if the drive is the first device
                           on the IDE bus.

      nec260_no_hd = 0     Set this to 1 if the drive is on an IDE bus
                           by itself.

    The defaults are set appropriately for my configuration, where the
    cdrom is the slave device on the first IDE bus, and the master
    device is a hard drive.  For the case of a cdrom configured as the
    first device on a second IDE controller with nothing else on that
    IDE bus you would probably want to set

      nec260_irq = 15
      nec260_base = 0x170
      nec260_master = 1
       nec260_no_hd = 1

    Note that since the last release, the default major device number
    has changed from 22 to 26.  This is because 22 conflicted with the
    atdisk2 patches.  You can change this back to 22 if you prefer.

  - Run make to produce nec260.o.  The driver will be compiled to work
    with the version of the kernel which you have in the source
    directory.  If you change the kernel version, you will also have
    to rebuild the driver.

  - Load the driver into the system with insmod.  At this point, you
    can override any of the configuration options by adding the
    assignment to the insmod command, like

      insmod nec260.o nec260_major=22

  - Create a block device special file with the appropriate major
    number.  I've been calling it `nec260'.  For example, if you are
    using the default major number of 26, you should say something
    like

      mknod /dev/nec260 b 26 0

  - If you have a disk in the drive, you should now be able to cat
    from it, or mount a filesystem.  When mounting a cdrom volume, you
    must specify read-only, or the system will complain:

      mount -r -t iso9660 /dev/nec260 /mnt

  - If the drive is dismounted, you can unload the driver with rmmod.

If you get consistent I/O errors when you try to cat the drive and the
drive activity light never comes on, double check that you have the
configuration variables set correctly.  Otherwise, you should be able
to find any error messages in the system log.

I have had one person report that for his drive, which was alone on a
second IDE controller, the device status register always returns 255
after a cold boot until the drive is sent at least one command.  If
you think you may have this problem, try defining the preprocessor
symbol `SHY_DEVICE' when compiling.

I much prefer to have the driver be a dynamically loadable module.
However, in some cases, it may be more convenient to link the driver
directly into the kernel.  To accomplish this:

  - Apply the additional kernel patches contained in
    linked-in-kernel.diffs.

  - Copy nec260.c to drivers/block/nec260.c.

  - Do a `make config', enabling the NEC260 support, followed by a
    `make dep', and then whatever you usually do to recompile the
    kernel.

hope all this helps someone,
sss
snyder@fnald0.fnal.gov