Linux-2.6.12-rc2v2.6.12-rc2

Initial git repository build. I'm not bothering with the full history,
even though we have it. We can create a separate "historical" git
archive of that later if we want to, and in the meantime it's about
3.2GB when imported into git - space that would just make the early
git days unnecessarily complicated, when we don't have a lot of good
infrastructure for it.

Let it rip!

1 files changed, 1402 insertions, 0 deletions

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+
+               -=< The IBM Microchannel SCSI-Subsystem >=-
+	       
+	                 for the IBM PS/2 series
+		 
+	  	   Low Level Software-Driver for Linux
+		 
+     Copyright (c) 1995 Strom Systems, Inc. under the terms of the GNU 
+  General Public License. Originally written by Martin Kolinek, December 1995.
+   Officially modified and maintained by Michael Lang since January 1999.
+	   
+ 	                       Version 4.0a
+	
+   Last update: January 3, 2001
+   
+   Before you Start
+   ----------------
+   This is the common README.ibmmca file for all driver releases of the 
+   IBM MCA SCSI driver for Linux. Please note, that driver releases 4.0
+   or newer do not work with kernel versions older than 2.4.0, while driver
+   versions older than 4.0 do not work with kernels 2.4.0 or later! If you
+   try to compile your kernel with the wrong driver source, the 
+   compilation is aborted and you get a corresponding error message. This is
+   no bug in the driver. It prevents you from using the wrong sourcecode
+   with the wrong kernel version.
+
+   Authors of this Driver
+   ----------------------
+    - Chris Beauregard (improvement of the SCSI-device mapping by the driver)
+    - Martin Kolinek (origin, first release of this driver)
+    - Klaus Kudielka (multiple SCSI-host management/detection, adaption to
+                      Linux Kernel 2.1.x, module support)
+    - Michael Lang (assigning original pun/lun mapping, dynamical ldn
+                    assignment, rewritten adapter detection, this file, 
+		    patches, official driver maintenance and subsequent 
+		    debugging, related with the driver)
+
+   Table of Contents
+   -----------------
+   1 Abstract
+   2 Driver Description
+     2.1  IBM SCSI-Subsystem Detection
+     2.2  Physical Units, Logical Units, and Logical Devices
+     2.3  SCSI-Device Recognition and dynamical ldn Assignment
+     2.4  SCSI-Device Order
+     2.5  Regular SCSI-Command-Processing
+     2.6  Abort & Reset Commands
+     2.7  Disk Geometry
+     2.8  Kernel Boot Option
+     2.9  Driver Module Support
+     2.10 Multiple Hostadapter Support
+     2.11 /proc/scsi-Filesystem Information
+     2.12 /proc/mca-Filesystem Information
+     2.13 Supported IBM SCSI-Subsystems
+     2.14 Linux Kernel Versions
+   3 Code History
+   4 To do
+   5 Users' Manual
+     5.1 Commandline Parameters
+     5.2 Troubleshooting
+     5.3 Bugreports
+     5.4 Support WWW-page
+   6 References
+   7 Credits to
+     7.1 People
+     7.2 Sponsors & Supporters
+   8 Trademarks
+   9 Disclaimer
+
+                              * * *
+
+   1 Abstract
+   ----------
+   This README-file describes the IBM SCSI-subsystem low level driver for 
+   Linux. The descriptions which were formerly kept in the source-code have 
+   been taken out to this file to easify the codes' readability. The driver 
+   description has been updated, as most of the former description was already
+   quite outdated. The history of the driver development is also kept inside 
+   here. Multiple historical developments have been summarized to shorten the 
+   textsize a bit. At the end of this file you can find a small manual for 
+   this driver and hints to get it running on your machine.
+
+   2 Driver Description
+   --------------------
+   2.1 IBM SCSI-Subsystem Detection
+   --------------------------------
+   This is done in the ibmmca_detect() function. It first checks, if the
+   Microchannel-bus support is enabled, as the IBM SCSI-subsystem needs the
+   Microchannel. In a next step, a free interrupt is chosen and the main
+   interrupt handler is connected to it to handle answers of the SCSI-
+   subsystem(s). If the F/W SCSI-adapter is forced by the BIOS to use IRQ11
+   instead of IRQ14, IRQ11 is used for the IBM SCSI-2 F/W adapter. In a 
+   further step it is checked, if the adapter gets detected by force from
+   the kernel commandline, where the I/O port and the SCSI-subsystem id can 
+   be specified. The next step checks if there is an integrated SCSI-subsystem
+   installed. This register area is fixed through all IBM PS/2 MCA-machines 
+   and appears as something like a virtual slot 10 of the MCA-bus. On most
+   PS/2 machines, the POS registers of slot 10 are set to 0xff or 0x00 if not
+   integrated SCSI-controller is available. But on certain PS/2s, like model 
+   9595, this slot 10 is used to store other information which at earlier
+   stage confused the driver and resulted in the detection of some ghost-SCSI. 
+   If POS-register 2 and 3 are not 0x00 and not 0xff, but all other POS
+   registers are either 0xff or 0x00, there must be an integrated SCSI-
+   subsystem present and it will be registered as IBM Integrated SCSI-
+   Subsystem. The next step checks, if there is a slot-adapter installed on 
+   the MCA-bus. To get this, the first two POS-registers, that represent the 
+   adapter ID are checked. If they fit to one of the ids, stored in the 
+   adapter list, a SCSI-subsystem is assumed to be found in a slot and will be 
+   registered. This check is done through all possible MCA-bus slots to allow 
+   more than one SCSI-adapter to be present in the PS/2-system and this is 
+   already the first point of problems. Looking into the technical reference 
+   manual for the IBM PS/2 common interfaces, the POS2 register must have 
+   different interpretation of its single bits to avoid overlapping I/O
+   regions. While one can assume, that the integrated subsystem has a fix 
+   I/O-address at 0x3540 - 0x3547, further installed IBM SCSI-adapters must 
+   use a different I/O-address. This is expressed by bit 1 to 3 of POS2 
+   (multiplied by 8 + 0x3540). Bits 2 and 3 are reserved for the integrated 
+   subsystem, but not for the adapters! The following list shows, how the 
+   bits of POS2 and POS3 should be interpreted.
+   
+   The POS2-register of all PS/2 models' integrated SCSI-subsystems has the 
+   following interpretation of bits:
+                           Bit 7 - 4 : Chip Revision ID (Release)
+                           Bit 3 - 2 : Reserved
+                           Bit 1     : 8k NVRAM Disabled
+                           Bit 0     : Chip Enable (EN-Signal)
+   The POS3-register is interpreted as follows (for most IBM SCSI-subsys.):
+                           Bit 7 - 5 : SCSI ID
+                           Bit 4 - 0 : Reserved = 0
+   The slot-adapters have different interpretation of these bits. The IBM SCSI
+   adapter (w/Cache) and the IBM SCSI-2 F/W adapter use the following
+   interpretation of the POS2 register:
+                           Bit 7 - 4 : ROM Segment Address Select
+			   Bit 3 - 1 : Adapter I/O Address Select (*8+0x3540)
+			   Bit 0     : Adapter Enable (EN-Signal)
+   and for the POS3 register:
+                           Bit 7 - 5 : SCSI ID 
+			   Bit 4     : Fairness Enable (SCSI ID3 f. F/W)
+			   Bit 3 - 0 : Arbitration Level
+   The most modern product of the series is the IBM SCSI-2 F/W adapter, it 
+   allows dual-bus SCSI and SCSI-wide addressing, which means, PUNs may be
+   between 0 and 15. Here, Bit 4 is the high-order bit of the 4-bit wide
+   adapter PUN expression. In short words, this means, that IBM PS/2 machines 
+   can only support 1 single integrated subsystem by default. Additional
+   slot-adapters get ports assigned by the automatic configuration tool.
+
+   One day I found a patch in ibmmca_detect(), forcing the I/O-address to be 
+   0x3540 for integrated SCSI-subsystems, there was a remark placed, that on 
+   integrated IBM SCSI-subsystems of model 56, the POS2 register was showing 5.
+   This means, that really for these models, POS2 has to be interpreted
+   sticking to the technical reference guide. In this case, the bit 2 (4) is 
+   a reserved bit and may not be interpreted. These differences between the 
+   adapters and the integrated controllers are taken into account by the 
+   detection routine of the driver on from version >3.0g. 
+
+   Every time, a SCSI-subsystem is discovered, the ibmmca_register() function
+   is called. This function checks first, if the requested area for the I/O-
+   address of this SCSI-subsystem is still available and assigns this I/O-
+   area to the SCSI-subsystem. There are always 8 sequential I/O-addresses
+   taken for each individual SCSI-subsystem found, which are:
+   
+     Offset            Type                  Permissions
+       0     Command Interface Register 1    Read/Write
+       1     Command Interface Register 2    Read/Write
+       2     Command Interface Register 3    Read/Write
+       3     Command Interface Register 4    Read/Write
+       4     Attention Register              Read/Write
+       5     Basic Control Register          Read/Write
+       6     Interrupt Status Register       Read
+       7     Basic Status Register           Read
+   
+   After the I/O-address range is assigned, the host-adapter is assigned
+   to a local structure which keeps all adapter information needed for the
+   driver itself and the mid- and higher-level SCSI-drivers. The SCSI pun/lun
+   and the adapters' ldn tables are initialized and get probed afterwards by
+   the check_devices() function. If no further adapters are found, 
+   ibmmca_detect() quits.
+   
+   2.2 Physical Units, Logical Units, and Logical Devices
+   ------------------------------------------------------
+   There can be up to 56 devices on the SCSI bus (besides the adapter):
+   there are up to 7 "physical units" (each identified by physical unit 
+   number or pun, also called the scsi id, this is the number you select
+   with hardware jumpers), and each physical unit can have up to 8 
+   "logical units" (each identified by logical unit number, or lun, 
+   between 0 and 7). The IBM SCSI-2 F/W adapter offers this on up to two
+   busses and provides support for 30 logical devices at the same time, where
+   in wide-addressing mode you can have 16 puns with 32 luns on each device.
+   This section dexribes you the handling of devices on non-F/W adapters.
+   Just imagine, that you can have 16 * 32 = 512 devices on a F/W adapter
+   which means a lot of possible devices for such a small machine.
+
+   Typically the adapter has pun=7, so puns of other physical units
+   are between 0 and 6(15). On a wide-adapter a pun higher than 7 is
+   possible, but is normally not used. Almost all physical units have only 
+   one logical unit, with lun=0. A CD-ROM jukebox would be an example of a 
+   physical unit with more than one logical unit.
+
+   The embedded microprocessor of the IBM SCSI-subsystem hides the complex
+   two-dimensional (pun,lun) organization from the operating system.
+   When the machine is powered-up (or rebooted), the embedded microprocessor 
+   checks, on its own, all 56 possible (pun,lun) combinations, and the first 
+   15 devices found are assigned into a one-dimensional array of so-called 
+   "logical devices", identified by "logical device numbers" or ldn. The last 
+   ldn=15 is reserved for the subsystem itself. Wide adapters may have 
+   to check up to 15 * 8 = 120 pun/lun combinations.
+   
+   2.3 SCSI-Device Recognition and Dynamical ldn Assignment
+   --------------------------------------------------------
+   One consequence of information hiding is that the real (pun,lun)    
+   numbers are also hidden. The two possibilities to get around this problem
+   is to offer fake pun/lun combinations to the operating system or to 
+   delete the whole mapping of the adapter and to reassign the ldns, using
+   the immediate assign command of the SCSI-subsystem for probing through
+   all possible pun/lun combinations. a ldn is a "logical device number"
+   which is used by IBM SCSI-subsystems to access some valid SCSI-device.
+   At the beginning of the development of this driver, the following approach 
+   was used:
+   
+   First, the driver checked the ldn's (0 to 6) to find out which ldn's
+   have devices assigned. This was done by the functions check_devices() and
+   device_exists(). The interrupt handler has a special paragraph of code
+   (see local_checking_phase_flag) to assist in the checking. Assume, for
+   example, that three logical devices were found assigned at ldn 0, 1, 2.
+   These are presented to the upper layer of Linux SCSI driver
+   as devices with bogus (pun, lun) equal to (0,0), (1,0), (2,0). 
+   On the other hand, if the upper layer issues a command to device
+   say (4,0), this driver returns DID_NO_CONNECT error.
+
+   In a second step of the driver development, the following improvement has
+   been applied: The first approach limited the number of devices to 7, far
+   fewer than the 15 that it could usem then it just maped ldn -> 
+   (ldn/8,ldn%8) for pun,lun.  We ended up with a real mishmash of puns
+   and luns, but it all seemed to work.
+
+   The latest development, which is implemented from the driver version 3.0
+   and later, realizes the device recognition in the following way:
+   The physical SCSI-devices on the SCSI-bus are probed via immediate_assign- 
+   and device_inquiry-commands, that is all implemented in a completely new
+   made check_devices() subroutine. This delivers an exact map of the physical
+   SCSI-world that is now stored in the get_scsi[][]-array. This means,
+   that the once hidden pun,lun assignment is now known to this driver.
+   It no longer believes in default-settings of the subsystem and maps all
+   ldns to existing pun,lun "by foot". This assures full control of the ldn
+   mapping and allows dynamical remapping of ldns to different pun,lun, if
+   there are more SCSI-devices installed than ldns available (n>15). The
+   ldns from 0 to 6 get 'hardwired' by this driver to puns 0 to 7 at lun=0,
+   excluding the pun of the subsystem. This assures, that at least simple 
+   SCSI-installations have optimum access-speed and are not touched by
+   dynamical remapping. The ldns 7 to 14 are put to existing devices with 
+   lun>0 or to non-existing devices, in order to satisfy the subsystem, if 
+   there are less than 15 SCSI-devices connected. In the case of more than 15 
+   devices, the dynamical mapping goes active. If the get_scsi[][] reports a 
+   device to be existant, but it has no ldn assigned, it gets a ldn out of 7 
+   to 14. The numbers are assigned in cyclic order. Therefore it takes 8 
+   dynamical reassignments on the SCSI-devices, until a certain device 
+   loses its ldn again. This assures, that dynamical remapping is avoided 
+   during intense I/O between up to 15 SCSI-devices (means pun,lun 
+   combinations). A further advantage of this method is, that people who
+   build their kernel without probing on all luns will get what they expect,
+   because the driver just won't assign everything with lun>0 when 
+   multpile lun probing is inactive.
+ 
+   2.4 SCSI-Device Order
+   ---------------------
+   Because of the now correct recognition of physical pun,lun, and 
+   their report to mid-level- and higher-level-drivers, the new reported puns
+   can be different from the old, faked puns. Therefore, Linux will eventually
+   change /dev/sdXXX assignments and prompt you for corrupted superblock
+   repair on boottime. In this case DO NOT PANIC, YOUR DISKS ARE STILL OK!!!
+   You have to reboot (CTRL-D) with an old kernel and set the /etc/fstab-file
+   entries right. After that, the system should come up as errorfree as before.
+   If your boot-partition is not coming up, also edit the /etc/lilo.conf-file
+   in a Linux session booted on old kernel and run lilo before reboot. Check
+   lilo.conf anyway to get boot on other partitions with foreign OSes right
+   again. But there exists a feature of this driver that allows you to change
+   the assignment order of the SCSI-devices by flipping the PUN-assignment.
+   See the next paragraph for a description.
+ 
+   The problem for this is, that Linux does not assign the SCSI-devices in the
+   way as described in the ANSI-SCSI-standard. Linux assigns /dev/sda to 
+   the device with at minimum id 0. But the first drive should be at id 6,
+   because for historical reasons, drive at id 6 has, by hardware, the highest
+   priority and a drive at id 0 the lowest. IBM was one of the rare producers,
+   where the BIOS assigns drives belonging to the ANSI-SCSI-standard. Most 
+   other producers' BIOS does not (I think even Adaptec-BIOS). The 
+   IBMMCA_SCSI_ORDER_STANDARD flag, which you set while configuring the
+   kernel enables to choose the preferred way of SCSI-device-assignment. 
+   Defining this flag would result in Linux determining the devices in the 
+   same order as DOS and OS/2 does on your MCA-machine. This is also standard 
+   on most industrial computers and OSes, like e.g. OS-9. Leaving this flag 
+   undefined will get your devices ordered in the default way of Linux. See 
+   also the remarks of Chris Beauregard from Dec 15, 1997 and the followups 
+   in section 3.
+   
+   2.5 Regular SCSI-Command-Processing
+   -----------------------------------
+   Only three functions get involved: ibmmca_queuecommand(), issue_cmd(),
+   and interrupt_handler().
+
+   The upper layer issues a scsi command by calling function 
+   ibmmca_queuecommand(). This function fills a "subsystem control block"
+   (scb) and calls a local function issue_cmd(), which writes a scb 
+   command into subsystem I/O ports. Once the scb command is carried out, 
+   the interrupt_handler() is invoked. If a device is determined to be 
+   existant and it has not assigned any ldn, it gets one dynamically.
+   For this, the whole stuff is done in ibmmca_queuecommand().
+
+   2.6 Abort & Reset Commands
+   --------------------------
+   These are implemented with busy waiting for interrupt to arrive.
+   ibmmca_reset() and ibmmca_abort() do not work sufficently well
+   up to now and need still a lot of development work. But, this seems
+   to be even a problem with other SCSI-low level drivers, too. However,
+   this should be no excuse.
+
+   2.7 Disk Geometry
+   -----------------
+   The ibmmca_biosparams() function should return the same disk geometry 
+   as the bios. This is needed for fdisk, etc. The returned geometry is 
+   certainly correct for disks smaller than 1 gigabyte. In the meantime,
+   it has been proved, that this works fine even with disks larger than
+   1 gigabyte.
+
+   2.8 Kernel Boot Option
+   ----------------------
+   The function ibmmca_scsi_setup() is called if option ibmmcascsi=n 
+   is passed to the kernel. See file linux/init/main.c for details.
+   
+   2.9 Driver Module Support
+   -------------------------
+   Is implemented and tested by K. Kudielka. This could probably not work
+   on kernels <2.1.0.
+  
+   2.10 Multiple Hostadapter Support
+   ---------------------------------
+   This driver supports up to eight interfaces of type IBM-SCSI-Subsystem. 
+   Integrated-, and MCA-adapters are automatically recognized. Unrecognizable
+   IBM-SCSI-Subsystem interfaces can be specified as kernel-parameters.
+ 
+   2.11 /proc/scsi-Filesystem Information
+   --------------------------------------
+   Information about the driver condition is given in 
+   /proc/scsi/ibmmca/<host_no>. ibmmca_proc_info() provides this information.
+   
+   This table is quite informative for interested users. It shows the load
+   of commands on the subsystem and wether you are running the bypassed 
+   (software) or integrated (hardware) SCSI-command set (see below). The
+   amount of accesses is shown. Read, write, modeselect is shown separately
+   in order to help debugging problems with CD-ROMs or tapedrives.
+   
+   The following table shows the list of 15 logical device numbers, that are
+   used by the SCSI-subsystem. The load on each ldn is shown in the table,
+   again, read and write commands are split. The last column shows the amount
+   of reassignments, that have been applied to the ldns, if you have more than
+   15 pun/lun combinations available on the SCSI-bus.
+   
+   The last two tables show the pun/lun map and the positions of the ldns
+   on this pun/lun map. This may change during operation, when a ldn is
+   reassigned to another pun/lun combination. If the necessity for dynamical
+   assignments is set to 'no', the ldn structure keeps static.
+   
+   2.12 /proc/mca-Filesystem Information
+   -------------------------------------
+   The slot-file contains all default entries and in addition chip and I/O-
+   address information of the SCSI-subsystem. This information is provided
+   by ibmmca_getinfo().
+   
+   2.13 Supported IBM SCSI-Subsystems
+   ----------------------------------
+   The following IBM SCSI-subsystems are supported by this driver:
+   
+     - IBM Fast/Wide SCSI-2 Adapter
+     - IBM 7568 Industrial Computer SCSI Adapter w/Cache
+     - IBM Expansion Unit SCSI Controller
+     - IBM SCSI Adapter w/Cache
+     - IBM SCSI Adapter
+     - IBM Integrated SCSI Controller
+     - All clones, 100% compatible with the chipset and subsystem command
+       system of IBM SCSI-adapters (forced detection)
+     
+   2.14 Linux Kernel Versions
+   --------------------------
+   The IBM SCSI-subsystem low level driver is prepared to be used with
+   all versions of Linux between 2.0.x and 2.4.x. The compatibility checks
+   are fully implemented up from version 3.1e of the driver. This means, that
+   you just need the latest ibmmca.h and ibmmca.c file and copy it in the
+   linux/drivers/scsi directory. The code is automatically adapted during 
+   kernel compilation. This is different from kernel 2.4.0! Here version 
+   4.0 or later of the driver must be used for kernel 2.4.0 or later. Version
+   4.0 or later does not work together with older kernels! Driver versions
+   older than 4.0 do not work together with kernel 2.4.0 or later. They work
+   on all older kernels.
+
+   3 Code History
+   --------------
+   Jan 15 1996:  First public release.
+   - Martin Kolinek
+
+   Jan 23 1996:  Scrapped code which reassigned scsi devices to logical
+   device numbers. Instead, the existing assignment (created
+   when the machine is powered-up or rebooted) is used. 
+   A side effect is that the upper layer of Linux SCSI 
+   device driver gets bogus scsi ids (this is benign), 
+   and also the hard disks are ordered under Linux the 
+   same way as they are under dos (i.e., C: disk is sda, 
+   D: disk is sdb, etc.).
+   - Martin Kolinek
+
+   I think that the CD-ROM is now detected only if a CD is 
+   inside CD_ROM while Linux boots. This can be fixed later,
+   once the driver works on all types of PS/2's.
+   - Martin Kolinek
+
+   Feb 7 1996:   Modified biosparam function. Fixed the CD-ROM detection. 
+   For now, devices other than harddisk and CD_ROM are 
+   ignored. Temporarily modified abort() function 
+   to behave like reset().
+   - Martin Kolinek
+
+   Mar 31 1996:  The integrated scsi subsystem is correctly found
+   in PS/2 models 56,57, but not in model 76. Therefore
+   the ibmmca_scsi_setup() function has been added today.
+   This function allows the user to force detection of
+   scsi subsystem. The kernel option has format
+   ibmmcascsi=n
+   where n is the scsi_id (pun) of the subsystem. Most likely, n is 7.
+   - Martin Kolinek
+
+   Aug 21 1996:  Modified the code which maps ldns to (pun,0).  It was
+   insufficient for those of us with CD-ROM changers.
+   - Chris Beauregard
+ 
+   Dec 14 1996: More improvements to the ldn mapping.  See check_devices
+   for details.  Did more fiddling with the integrated SCSI detection,
+   but I think it's ultimately hopeless without actually testing the
+   model of the machine.  The 56, 57, 76 and 95 (ultimedia) all have
+   different integrated SCSI register configurations.  However, the 56
+   and 57 are the only ones that have problems with forced detection.
+   - Chris Beauregard
+ 
+   Mar 8-16 1997: Modified driver to run as a module and to support 
+   multiple adapters. A structure, called ibmmca_hostdata, is now
+   present, containing all the variables, that were once only
+   available for one single adapter. The find_subsystem-routine has vanished.
+   The hardware recognition is now done in ibmmca_detect directly.
+   This routine checks for presence of MCA-bus, checks the interrupt
+   level and continues with checking the installed hardware.
+   Certain PS/2-models do not recognize a SCSI-subsystem automatically.
+   Hence, the setup defined by command-line-parameters is checked first.
+   Thereafter, the routine probes for an integrated SCSI-subsystem.
+   Finally, adapters are checked. This method has the advantage to cover all
+   possible combinations of multiple SCSI-subsystems on one MCA-board. Up to
+   eight SCSI-subsystems can be recognized and announced to the upper-level
+   drivers with this improvement. A set of defines made changes to other
+   routines as small as possible.
+   - Klaus Kudielka
+   
+   May 30 1997: (v1.5b)
+   1) SCSI-command capability enlarged by the recognition of MODE_SELECT.
+      This needs the RD-Bit to be disabled on IM_OTHER_SCSI_CMD_CMD which 
+      allows data to be written from the system to the device. It is a
+      necessary step to be allowed to set blocksize of SCSI-tape-drives and 
+      the tape-speed, whithout confusing the SCSI-Subsystem.
+   2) The recognition of a tape is included in the check_devices routine.
+      This is done by checking for TYPE_TAPE, that is already defined in
+      the kernel-scsi-environment. The markup of a tape is done in the 
+      global ldn_is_tape[] array. If the entry on index ldn 
+      is 1, there is a tapedrive connected.
+   3) The ldn_is_tape[] array is necessary to distinguish between tape- and 
+      other devices. Fixed blocklength devices should not cause a problem
+      with the SCB-command for read and write in the ibmmca_queuecommand
+      subroutine. Therefore, I only derivate the READ_XX, WRITE_XX for
+      the tape-devices, as recommended by IBM in this Technical Reference,
+      mentioned below. (IBM recommends to avoid using the read/write of the
+      subsystem, but the fact was, that read/write causes a command error from
+      the subsystem and this causes kernel-panic.)
+   4) In addition, I propose to use the ldn instead of a fix char for the
+      display of PS2_DISK_LED_ON(). On 95, one can distinguish between the
+      devices that are accessed. It shows activity and easyfies debugging.   
+   The tape-support has been tested with a SONY SDT-5200 and a HP DDS-2
+   (I do not know yet the type). Optimization and CD-ROM audio-support, 
+   I am working on ...
+   - Michael Lang
+   
+   June 19 1997: (v1.6b)
+   1) Submitting the extra-array ldn_is_tape[] -> to the local ld[]
+      device-array. 
+   2) CD-ROM Audio-Play seems to work now.
+   3) When using DDS-2 (120M) DAT-Tapes, mtst shows still density-code
+      0x13 for ordinary DDS (61000 BPM) instead 0x24 for DDS-2. This appears 
+      also on Adaptec 2940 adaptor in a PCI-System. Therefore, I assume that 
+      the problem is independent of the low-level-driver/bus-architecture.
+   4) Hexadecimal ldn on PS/2-95 LED-display.
+   5) Fixing of the PS/2-LED on/off that it works right with tapedrives and
+      does not confuse the disk_rw_in_progress counter.
+   - Michael Lang
+  
+   June 21 1997: (v1.7b)
+   1) Adding of a proc_info routine to inform in /proc/scsi/ibmmca/<host> the
+      outer-world about operational load statistics on the different ldns,
+      seen by the driver. Everybody that has more than one IBM-SCSI should
+      test this, because I only have one and cannot see what happens with more
+      than one IBM-SCSI hosts.
+   2) Definition of a driver version-number to have a better recognition of 
+      the source when there are existing too much releases that may confuse
+      the user, when reading about release-specific problems. Up to know,
+      I calculated the version-number to be 1.7. Because we are in BETA-test
+      yet, it is today 1.7b.
+   3) Sorry for the heavy bug I programmed on June 19 1997! After that, the
+      CD-ROM did not work any more! The C7-command was a fake impression
+      I got while programming. Now, the READ and WRITE commands for CD-ROM are
+      no longer running over the subsystem, but just over 
+      IM_OTHER_SCSI_CMD_CMD. On my observations (PS/2-95), now CD-ROM mounts
+      much faster(!) and hopefully all fancy multimedia-functions, like direct
+      digital recording from audio-CDs also work. (I tried it with cdda2wav
+      from the cdwtools-package and it filled up the harddisk immediately :-).)
+      To easify boolean logics, a further local device-type in ld[], called
+      is_cdrom has been included.
+   4) If one uses a SCSI-device of unsupported type/commands, one
+      immediately runs into a kernel-panic caused by Command Error. To better
+      understand which SCSI-command caused the problem, I extended this
+      specific panic-message slightly.
+   - Michael Lang
+ 
+   June 25 1997: (v1.8b)
+   1) Some cosmetical changes for the handling of SCSI-device-types.
+      Now, also CD-Burners / WORMs and SCSI-scanners should work. For
+      MO-drives I have no experience, therefore not yet supported.
+      In logical_devices I changed from different type-variables to one
+      called 'device_type' where the values, corresponding to scsi.h,
+      of a SCSI-device are stored.
+   2) There existed a small bug, that maps a device, coming after a SCSI-tape
+      wrong. Therefore, e.g. a CD-ROM changer would have been mapped wrong
+      -> problem removed.
+   3) Extension of the logical_device structure. Now it contains also device,
+      vendor and revision-level of a SCSI-device for internal usage.
+   - Michael Lang
+
+   June 26-29 1997: (v2.0b)
+   1) The release number 2.0b is necessary because of the completely new done
+      recognition and handling of SCSI-devices with the adapter. As I got
+      from Chris the hint, that the subsystem can reassign ldns dynamically,
+      I remembered this immediate_assign-command, I found once in the handbook.
+      Now, the driver first kills all ldn assignments that are set by default
+      on the SCSI-subsystem. After that, it probes on all puns and luns for
+      devices by going through all combinations with immediate_assign and
+      probing for devices, using device_inquiry. The found physical(!) pun,lun
+      structure is stored in get_scsi[][] as device types. This is followed
+      by the assignment of all ldns to existing SCSI-devices. If more ldns
+      than devices are available, they are assigned to non existing pun,lun
+      combinations to satisfy the adapter. With this, the dynamical mapping
+      was possible to implement. (For further info see the text in the 
+      source-code and in the description below. Read the description
+      below BEFORE installing this driver on your system!)
+   2) Changed the name IBMMCA_DRIVER_VERSION to IBMMCA_SCSI_DRIVER_VERSION.
+   3) The LED-display shows on PS/2-95 no longer the ldn, but the SCSI-ID
+      (pun) of the accessed SCSI-device. This is now senseful, because the 
+      pun known within the driver is exactly the pun of the physical device
+      and no longer a fake one.
+   4) The /proc/scsi/ibmmca/<host_no> consists now of the first part, where
+      hit-statistics of ldns is shown and a second part, where the maps of 
+      physical and logical SCSI-devices are displayed. This could be very 
+      interesting, when one is using more than 15 SCSI-devices in order to 
+      follow the dynamical remapping of ldns.
+   - Michael Lang
+ 
+   June 26-29 1997: (v2.0b-1)
+   1) I forgot to switch the local_checking_phase_flag to 1 and back to 0
+      in the dynamical remapping part in ibmmca_queuecommand for the 
+      device_exist routine. Sorry.
+   - Michael Lang
+ 
+   July 1-13 1997: (v3.0b,c)
+   1) Merging of the driver-developments of Klaus Kudielka and Michael Lang 
+      in order to get a optimum and unified driver-release for the 
+      IBM-SCSI-Subsystem-Adapter(s).
+         For people, using the Kernel-release >=2.1.0, module-support should 
+      be no problem. For users, running under <2.1.0, module-support may not 
+      work, because the methods have changed between 2.0.x and 2.1.x.
+   2) Added some more effective statistics for /proc-output.
+   3) Change typecasting at necessary points from (unsigned long) to
+      virt_to_bus().
+   4) Included #if... at special points to have specific adaption of the
+      driver to kernel 2.0.x and 2.1.x. It should therefore also run with 
+      later releases.
+   5) Magneto-Optical drives and medium-changers are also recognized, now.
+      Therefore, we have a completely gapfree recognition of all SCSI-
+      device-types, that are known by Linux up to kernel 2.1.31.
+   6) The flag SCSI_IBMMCA_DEV_RESET has been inserted. If it is set within
+      the configuration, each connected SCSI-device will get a reset command
+      during boottime. This can be necessary for some special SCSI-devices.
+      This flag should be included in Config.in.
+      (See also the new Config.in file.)
+   Probable next improvement: bad disk handler.
+   - Michael Lang
+ 
+   Sept 14 1997: (v3.0c)
+   1) Some debugging and speed optimization applied.
+   - Michael Lang
+
+   Dec 15, 1997
+    - chrisb@truespectra.com
+    - made the front panel display thingy optional, specified from the
+    command-line via ibmmcascsi=display.  Along the lines of the /LED
+    option for the OS/2 driver.
+    - fixed small bug in the LED display that would hang some machines.
+    - reversed ordering of the drives (using the
+    IBMMCA_SCSI_ORDER_STANDARD define).  This is necessary for two main
+    reasons:
+	- users who've already installed Linux won't be screwed.  Keep
+	in mind that not everyone is a kernel hacker.
+	- be consistent with the BIOS ordering of the drives.  In the
+	BIOS, id 6 is C:, id 0 might be D:.  With this scheme, they'd be
+	backwards.  This confuses the crap out of those heathens who've
+	got a impure Linux installation (which, <wince>, I'm one of).
+    This whole problem arises because IBM is actually non-standard with
+    the id to BIOS mappings.  You'll find, in fdomain.c, a similar
+    comment about a few FD BIOS revisions.  The Linux (and apparently
+    industry) standard is that C: maps to scsi id (0,0).  Let's stick
+    with that standard.
+    - Since this is technically a branch of my own, I changed the
+    version number to 3.0e-cpb.
+
+   Jan 17, 1998: (v3.0f)
+   1) Addition of some statistical info for /proc in proc_info.
+   2) Taking care of the SCSI-assignment problem, dealed by Chris at Dec 15
+      1997. In fact, IBM is right, concerning the assignment of SCSI-devices 
+      to driveletters. It is conform to the ANSI-definition of the SCSI-
+      standard to assign drive C: to SCSI-id 6, because it is the highest
+      hardware priority after the hostadapter (that has still today by
+      default everywhere id 7). Also realtime-operating systems that I use, 
+      like LynxOS and OS9, which are quite industrial systems use top-down
+      numbering of the harddisks, that is also starting at id 6. Now, one
+      sits a bit between two chairs. On one hand side, using the define
+      IBMMCA_SCSI_ORDER_STANDARD makes Linux assigning disks conform to
+      the IBM- and ANSI-SCSI-standard and keeps this driver downward
+      compatible to older releases, on the other hand side, people is quite
+      habituated in believing that C: is assigned to (0,0) and much other
+      SCSI-BIOS do so. Therefore, I moved the IBMMCA_SCSI_ORDER_STANDARD 
+      define out of the driver and put it into Config.in as subitem of 
+      'IBM SCSI support'. A help, added to Documentation/Configure.help 
+      explains the differences between saying 'y' or 'n' to the user, when 
+      IBMMCA_SCSI_ORDER_STANDARD prompts, so the ordinary user is enabled to 
+      choose the way of assignment, depending on his own situation and gusto.
+   3) Adapted SCSI_IBMMCA_DEV_RESET to the local naming convention, so it is
+      now called IBMMCA_SCSI_DEV_RESET.
+   4) Optimization of proc_info and its subroutines.
+   5) Added more in-source-comments and extended the driver description by
+      some explanation about the SCSI-device-assignment problem.
+   - Michael Lang
+   
+   Jan 18, 1998: (v3.0g)
+   1) Correcting names to be absolutely conform to the later 2.1.x releases.
+      This is necessary for 
+            IBMMCA_SCSI_DEV_RESET -> CONFIG_IBMMCA_SCSI_DEV_RESET
+            IBMMCA_SCSI_ORDER_STANDARD -> CONFIG_IBMMCA_SCSI_ORDER_STANDARD
+   - Michael Lang
+ 
+   Jan 18, 1999: (v3.1 MCA-team internal)
+   1) The multiple hosts structure is accessed from every subroutine, so there
+      is no longer the address of the device structure passed from function
+      to function, but only the hostindex. A call by value, nothing more. This
+      should really be understood by the compiler and the subsystem should get
+      the right values and addresses.
+   2) The SCSI-subsystem detection was not complete and quite hugely buggy up
+      to now, compared to the technical manual. The interpretation of the pos2
+      register is not as assumed by people before, therefore, I dropped a note
+      in the ibmmca_detect function to show the registers' interpretation.
+      The pos-registers of integrated SCSI-subsystems do not contain any 
+      information concerning the IO-port offset, really. Instead, they contain
+      some info about the adapter, the chip, the NVRAM .... The I/O-port is
+      fixed to 0x3540 - 0x3547. There can be more than one adapters in the 
+      slots and they get an offset for the I/O area in order to get their own
+      I/O-address area. See chapter 2 for detailed description. At least, the 
+      detection should now work right, even on models other than 95. The 95ers
+      came happily around the bug, as their pos2 register contains always 0 
+      in the critical area. Reserved bits are not allowed to be interpreted, 
+      therefore, IBM is allowed to set those bits as they like and they may 
+      really vary between different PS/2 models. So, now, no interpretation 
+      of reserved bits - hopefully no trouble here anymore.
+   3) The command error, which you may get on models 55, 56, 57, 70, 77 and
+      P70 may have been caused by the fact, that adapters of older design do
+      not like sending commands to non-existing SCSI-devices and will react
+      with a command error as a sign of protest. While this error is not
+      present on IBM SCSI Adapter w/cache, it appears on IBM Integrated SCSI
+      Adapters. Therefore, I implemented a workarround to forgive those 
+      adapters their protests, but it is marked up in the statisctis, so
+      after a successful boot, you can see in /proc/scsi/ibmmca/<host_number>
+      how often the command errors have been forgiven to the SCSI-subsystem.
+      If the number is bigger than 0, you have a SCSI subsystem of older
+      design, what should no longer matter.
+   4) ibmmca_getinfo() has been adapted very carefully, so it shows in the 
+      slotn file really, what is senseful to be presented.
+   5) ibmmca_register() has been extended in its parameter list in order to
+      pass the right name of the SCSI-adapter to Linux.
+   - Michael Lang
+
+   Feb 6, 1999: (v3.1)
+   1) Finally, after some 3.1Beta-releases, the 3.1 release. Sorry, for 
+      the delayed release, but it was not finished with the release of 
+      Kernel 2.2.0.
+   - Michael Lang
+   
+   Feb 10, 1999 (v3.1)
+   1) Added a new commandline parameter called 'bypass' in order to bypass
+      every integrated subsystem SCSI-command consequently in case of
+      troubles.
+   2) Concatenated read_capacity requests to the harddisks. It gave a lot
+      of troubles with some controllers and after I wanted to apply some
+      extensions, it jumped out in the same situation, on my w/cache, as like 
+      on D. Weinehalls' Model 56, having integrated SCSI. This gave me the 
+      descissive hint to move the code-part out and declare it global. Now,
+      it seems to work by far much better an more stable. Let us see, what
+      the world thinks of it...
+   3) By the way, only Sony DAT-drives seem to show density code 0x13. A
+      test with a HP drive gave right results, so the problem is vendor-
+      specific and not a problem of the OS or the driver.
+   - Michael Lang
+   
+   Feb 18, 1999 (v3.1d)
+   1) The abort command and the reset function have been checked for 
+      inconsistencies. From the logical point of thinking, they work
+      at their optimum, now, but as the subsystem does not answer with an
+      interrupt, abort never finishes, sigh...
+   2) Everything, that is accessed by a busmaster request from the adapter
+      is now declared as global variable, even the return-buffer in the
+      local checking phase. This assures, that no accesses to undefined memory
+      areas are performed.
+   3) In ibmmca.h, the line unchecked_isa_dma is added with 1 in order to
+      avoid memory-pointers for the areas higher than 16MByte in order to
+      be sure, it also works on 16-Bit Microchannel bus systems.
+   4) A lot of small things have been found, but nothing that endangered the
+      driver operations. Just it should be more stable, now.
+   - Michael Lang
+      
+   Feb 20, 1999 (v3.1e)
+   1) I took the warning from the Linux Kernel Hackers Guide serious and 
+      checked the cmd->result return value to the done-function very carefully.
+      It is obvious, that the IBM SCSI only delivers the tsb.dev_status, if
+      s