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 .. SPDX-License-Identifier: GPL-2.0
 
 =================================================
 The Linux NCR53C8XX/SYM53C8XX drivers README file
 =================================================
 
 Written by Gerard Roudier <groudier@free.fr>
 
 21 Rue Carnot
 
 95170 DEUIL LA BARRE - FRANCE
 
 29 May 1999
 
 .. Contents:
 
    1.  Introduction
    2.  Supported chips and SCSI features
    3.  Advantages of the enhanced 896 driver
          3.1 Optimized SCSI SCRIPTS
          3.2 New features of the SYM53C896 (64 bit PCI dual LVD SCSI controller)
    4.  Memory mapped I/O versus normal I/O
    5.  Tagged command queueing
    6.  Parity checking
    7.  Profiling information
    8.  Control commands
          8.1  Set minimum synchronous period
          8.2  Set wide size
          8.3  Set maximum number of concurrent tagged commands
          8.4  Set order type for tagged command
          8.5  Set debug mode
          8.6  Clear profile counters
          8.7  Set flag (no_disc)
          8.8  Set verbose level
          8.9  Reset all logical units of a target
          8.10 Abort all tasks of all logical units of a target
    9.  Configuration parameters
    10. Boot setup commands
          10.1 Syntax
          10.2 Available arguments
                 10.2.1  Master parity checking
                 10.2.2  Scsi parity checking
                 10.2.3  Scsi disconnections
                 10.2.4  Special features
                 10.2.5  Ultra SCSI support
                 10.2.6  Default number of tagged commands
                 10.2.7  Default synchronous period factor
                 10.2.8  Negotiate synchronous with all devices
                 10.2.9  Verbosity level
                 10.2.10 Debug mode
                 10.2.11 Burst max
                 10.2.12 LED support
                 10.2.13 Max wide
                 10.2.14 Differential mode
                 10.2.15 IRQ mode
                 10.2.16 Reverse probe
                 10.2.17 Fix up PCI configuration space
                 10.2.18 Serial NVRAM
                 10.2.19 Check SCSI BUS
                 10.2.20 Exclude a host from being attached
                 10.2.21 Suggest a default SCSI id for hosts
                 10.2.22 Enable use of IMMEDIATE ARBITRATION
          10.3 Advised boot setup commands
          10.4 PCI configuration fix-up boot option
          10.5 Serial NVRAM support boot option
          10.6 SCSI BUS checking boot option
          10.7 IMMEDIATE ARBITRATION boot option
    11. Some constants and flags of the ncr53c8xx.h header file
    12. Installation
    13. Architecture dependent features
    14. Known problems
          14.1 Tagged commands with Iomega Jaz device
          14.2 Device names change when another controller is added
          14.3 Using only 8 bit devices with a WIDE SCSI controller.
          14.4 Possible data corruption during a Memory Write and Invalidate
          14.5 IRQ sharing problems
    15. SCSI problem troubleshooting
          15.1 Problem tracking
          15.2 Understanding hardware error reports
    16. Synchronous transfer negotiation tables
          16.1 Synchronous timings for 53C875 and 53C860 Ultra-SCSI controllers
          16.2 Synchronous timings for fast SCSI-2 53C8XX controllers
    17. Serial NVRAM support (by Richard Waltham)
          17.1 Features
          17.2 Symbios NVRAM layout
          17.3 Tekram  NVRAM layout
    18. Support for Big Endian
          18.1 Big Endian CPU
          18.2 NCR chip in Big Endian mode of operations
 
 1. Introduction
 ===============
 
 The initial Linux ncr53c8xx driver has been a port of the ncr driver from
 FreeBSD that has been achieved in November 1995 by:
 
         - Gerard Roudier              <groudier@free.fr>
 
 The original driver has been written for 386bsd and FreeBSD by:
 
         - Wolfgang Stanglmeier        <wolf@cologne.de>
         - Stefan Esser                <se@mi.Uni-Koeln.de>
 
 It is now available as a bundle of 2 drivers:
 
 - ncr53c8xx generic driver that supports all the SYM53C8XX family including
   the earliest 810 rev. 1, the latest 896 (2 channel LVD SCSI controller) and
   the new 895A (1 channel LVD SCSI controller).
 - sym53c8xx enhanced driver (a.k.a. 896 drivers) that drops support of oldest
   chips in order to gain advantage of new features, as LOAD/STORE instructions
   available since the 810A and hardware phase mismatch available with the
   896 and the 895A.
 
 You can find technical information about the NCR 8xx family in the
 PCI-HOWTO written by Michael Will and in the SCSI-HOWTO written by
 Drew Eckhardt.
 
 Information about new chips is available at LSILOGIC web server:
 
           - http://www.lsilogic.com/
 
 SCSI standard documentations are available at SYMBIOS ftp server:
 
           - ftp://ftp.symbios.com/
 
 Useful SCSI tools written by Eric Youngdale are available at tsx-11:
 
           - ftp://tsx-11.mit.edu/pub/linux/ALPHA/scsi/scsiinfo-X.Y.tar.gz
           - ftp://tsx-11.mit.edu/pub/linux/ALPHA/scsi/scsidev-X.Y.tar.gz
 
 These tools are not ALPHA but quite clean and work quite well.
 It is essential you have the 'scsiinfo' package.
 
 This short documentation describes the features of the generic and enhanced
 drivers, configuration parameters and control commands available through
 the proc SCSI file system read / write operations.
 
 This driver has been tested OK with linux/i386, Linux/Alpha and Linux/PPC.
 
 Latest driver version and patches are available at:
 
           - ftp://ftp.tux.org/pub/people/gerard-roudier
 
 or
 
           - ftp://ftp.symbios.com/mirror/ftp.tux.org/pub/tux/roudier/drivers
 
 I am not a native speaker of English and there are probably lots of
 mistakes in this README file. Any help will be welcome.
 
 
 2. Supported chips and SCSI features
 ====================================
 
 The following features are supported for all chips:
 
         - Synchronous negotiation
         - Disconnection
         - Tagged command queuing
         - SCSI parity checking
         - Master parity checking
 
 "Wide negotiation" is supported for chips that allow it.  The
 following table shows some characteristics of NCR 8xx family chips
 and what drivers support them.
 
 +--------+-----------+-----+-----------+------------+------------+------------+
 |        |           |     |           |            |Supported by|Supported by|
 |        |On board   |     |           |            |the generic |the enhanced|
 |Chip    |SDMS BIOS  |Wide |SCSI std.  | Max. sync  |driver      |driver      |
 +--------+-----------+-----+-----------+------------+------------+------------+
 |810     |  N        | N   |  FAST10   | 10 MB/s    |    Y       |    N       |
 +--------+-----------+-----+-----------+------------+------------+------------+
 |810A    |  N        | N   |  FAST10   | 10 MB/s    |    Y       |    Y       |
 +--------+-----------+-----+-----------+------------+------------+------------+
 |815     |  Y        | N   |  FAST10   | 10 MB/s    |    Y       |    N       |
 +--------+-----------+-----+-----------+------------+------------+------------+
 |825     |  Y        | Y   |  FAST10   | 20 MB/s    |    Y       |    N       |
 +--------+-----------+-----+-----------+------------+------------+------------+
 |825A    |  Y        | Y   |  FAST10   | 20 MB/s    |    Y       |    Y       |
 +--------+-----------+-----+-----------+------------+------------+------------+
 |860     |  N        | N   |  FAST20   | 20 MB/s    |    Y       |    Y       |
 +--------+-----------+-----+-----------+------------+------------+------------+
 |875     |  Y        | Y   |  FAST20   | 40 MB/s    |    Y       |    Y       |
 +--------+-----------+-----+-----------+------------+------------+------------+
 |876     |  Y        | Y   |  FAST20   | 40 MB/s    |    Y       |    Y       |
 +--------+-----------+-----+-----------+------------+------------+------------+
 |895     |  Y        | Y   |  FAST40   | 80 MB/s    |    Y       |    Y       |
 +--------+-----------+-----+-----------+------------+------------+------------+
 |895A    |  Y        | Y   |  FAST40   | 80 MB/s    |    Y       |    Y       |
 +--------+-----------+-----+-----------+------------+------------+------------+
 |896     |  Y        | Y   |  FAST40   | 80 MB/s    |    Y       |    Y       |
 +--------+-----------+-----+-----------+------------+------------+------------+
 |897     |  Y        | Y   |  FAST40   | 80 MB/s    |    Y       |    Y       |
 +--------+-----------+-----+-----------+------------+------------+------------+
 |1510D   |  Y        | Y   |  FAST40   | 80 MB/s    |    Y       |    Y       |
 +--------+-----------+-----+-----------+------------+------------+------------+
 |1010    |  Y        | Y   |  FAST80   |160 MB/s    |    N       |    Y       |
 +--------+-----------+-----+-----------+------------+------------+------------+
 |1010_66 |  Y        | Y   |  FAST80   |160 MB/s    |    N       |    Y       |
 |[1]_    |           |     |           |            |            |            |
 +--------+-----------+-----+-----------+------------+------------+------------+
 
 .. [1] Chip supports 33MHz and 66MHz PCI buses.
 
 
 Summary of other supported features:
 
 :Module:                allow to load the driver
 :Memory mapped I/O:     increases performance
 :Profiling information: read operations from the proc SCSI file system
 :Control commands:      write operations to the proc SCSI file system
 :Debugging information: written to syslog (expert only)
 :Serial NVRAM:          Symbios and Tekram formats
 
 - Scatter / gather
 - Shared interrupt
 - Boot setup commands
 
 
 3. Advantages of the enhanced 896 driver
 ========================================
 
 3.1 Optimized SCSI SCRIPTS
 --------------------------
 
 The 810A, 825A, 875, 895, 896 and 895A support new SCSI SCRIPTS instructions
 named LOAD and STORE that allow to move up to 1 DWORD from/to an IO register
 to/from memory much faster that the MOVE MEMORY instruction that is supported
 by the 53c7xx and 53c8xx family.
 The LOAD/STORE instructions support absolute and DSA relative addressing
 modes.  The SCSI SCRIPTS had been entirely rewritten using LOAD/STORE instead
 of MOVE MEMORY instructions.
 
 3.2 New features of the SYM53C896 (64 bit PCI dual LVD SCSI controller)
 -----------------------------------------------------------------------
 
 The 896 and the 895A allows handling of the phase mismatch context from
 SCRIPTS (avoids the phase mismatch interrupt that stops the SCSI processor
 until the C code has saved the context of the transfer).
 Implementing this without using LOAD/STORE instructions would be painful
 and I didn't even want to try it.
 
 The 896 chip supports 64 bit PCI transactions and addressing, while the
 895A supports 32 bit PCI transactions and 64 bit addressing.
 The SCRIPTS processor of these chips is not true 64 bit, but uses segment
 registers for bit 32-63. Another interesting feature is that LOAD/STORE
 instructions that address the on-chip RAM (8k) remain internal to the chip.
 
 Due to the use of LOAD/STORE SCRIPTS instructions, this driver does not
 support the following chips:
 
 - SYM53C810 revision < 0x10 (16)
 - SYM53C815 all revisions
 - SYM53C825 revision < 0x10 (16)
 
 4. Memory mapped I/O versus normal I/O
 ======================================
 
 Memory mapped I/O has less latency than normal I/O.  Since
 linux-1.3.x, memory mapped I/O is used rather than normal I/O.  Memory
 mapped I/O seems to work fine on most hardware configurations, but
 some poorly designed motherboards may break this feature.
 
 The configuration option CONFIG_SCSI_NCR53C8XX_IOMAPPED forces the
 driver to use normal I/O in all cases.
 
 
 5. Tagged command queueing
 ==========================
 
 Queuing more than 1 command at a time to a device allows it to perform
 optimizations based on actual head positions and its mechanical
 characteristics. This feature may also reduce average command latency.
 In order to really gain advantage of this feature, devices must have
 a reasonable cache size (No miracle is to be expected for a low-end
 hard disk with 128 KB or less).
 Some known SCSI devices do not properly support tagged command queuing.
 Generally, firmware revisions that fix this kind of problems are available
 at respective vendor web/ftp sites.
 All I can say is that the hard disks I use on my machines behave well with
 this driver with tagged command queuing enabled:
 
 - IBM S12 0662
 - Conner 1080S
 - Quantum Atlas I
 - Quantum Atlas II
 
 If your controller has NVRAM, you can configure this feature per target
 from the user setup tool. The Tekram Setup program allows to tune the
 maximum number of queued commands up to 32. The Symbios Setup only allows
 to enable or disable this feature.
 
 The maximum number of simultaneous tagged commands queued to a device
 is currently set to 8 by default.  This value is suitable for most SCSI
 disks.  With large SCSI disks (>= 2GB, cache >= 512KB, average seek time
 <= 10 ms), using a larger value may give better performances.
 
 The sym53c8xx driver supports up to 255 commands per device, and the
 generic ncr53c8xx driver supports up to 64, but using more than 32 is
 generally not worth-while, unless you are using a very large disk or disk
 array. It is noticeable that most of recent hard disks seem not to accept
 more than 64 simultaneous commands. So, using more than 64 queued commands
 is probably just resource wasting.
 
 If your controller does not have NVRAM or if it is managed by the SDMS
 BIOS/SETUP, you can configure tagged queueing feature and device queue
 depths from the boot command-line. For example::
 
   ncr53c8xx=tags:4/t2t3q15-t4q7/t1u0q32
 
 will set tagged commands queue depths as follow:
 
 - target 2  all luns  on controller 0 --> 15
 - target 3  all luns  on controller 0 --> 15
 - target 4  all luns  on controller 0 -->  7
 - target 1  lun 0     on controller 1 --> 32
 - all other target/lun                -->  4
 
 In some special conditions, some SCSI disk firmwares may return a
 QUEUE FULL status for a SCSI command. This behaviour is managed by the
 driver using the following heuristic:
 
 - Each time a QUEUE FULL status is returned, tagged queue depth is reduced
   to the actual number of disconnected commands.
 
 - Every 1000 successfully completed SCSI commands, if allowed by the
   current limit, the maximum number of queueable commands is incremented.
 
 Since QUEUE FULL status reception and handling is resource wasting, the
 driver notifies by default this problem to user by indicating the actual
 number of commands used and their status, as well as its decision on the
 device queue depth change.
 The heuristic used by the driver in handling QUEUE FULL ensures that the
 impact on performances is not too bad. You can get rid of the messages by
 setting verbose level to zero, as follow:
 
 1st method:
             boot your system using 'ncr53c8xx=verb:0' option.
 
 2nd method:
             apply "setverbose 0" control command to the proc fs entry
             corresponding to your controller after boot-up.
 
 6. Parity checking
 ==================
 
 The driver supports SCSI parity checking and PCI bus master parity
 checking.  These features must be enabled in order to ensure safe data
 transfers.  However, some flawed devices or mother boards will have
 problems with parity. You can disable either PCI parity or SCSI parity
 checking by entering appropriate options from the boot command line.
 (See 10: Boot setup commands).
 
 7. Profiling information
 ========================
 
 Profiling information is available through the proc SCSI file system.
 Since gathering profiling information may impact performances, this
 feature is disabled by default and requires a compilation configuration
 option to be set to Y.
 
 The device associated with a host has the following pathname::
 
           /proc/scsi/ncr53c8xx/N     (N=0,1,2 ....)
 
 Generally, only 1 board is used on hardware configuration, and that device is::
 
           /proc/scsi/ncr53c8xx/0
 
 However, if the driver has been made as module, the number of the
 hosts is incremented each time the driver is loaded.
 
 In order to display profiling information, just enter::
 
          cat /proc/scsi/ncr53c8xx/0
 
 and you will get something like the following text::
 
     General information:
     Chip NCR53C810, device id 0x1, revision id 0x2
     IO port address 0x6000, IRQ number 10
     Using memory mapped IO at virtual address 0x282c000
     Synchronous transfer period 25, max commands per lun 4
     Profiling information:
     num_trans    = 18014
     num_kbytes   = 671314
     num_disc     = 25763
     num_break    = 1673
     num_int      = 1685
     num_fly      = 18038
     ms_setup     = 4940
     ms_data      = 369940
     ms_disc      = 183090
     ms_post      = 1320
 
 General information is easy to understand. The device ID and the
 revision ID identify the SCSI chip as follows:
 
 ======= ============= ===========
 Chip    Device id     Revision Id
 ======= ============= ===========
 810       0x1            <  0x10
 810A      0x1            >= 0x10
 815       0x4
 825       0x3            <  0x10
 860       0x6
 825A      0x3            >= 0x10
 875       0xf
 895       0xc
 ======= ============= ===========
 
 The profiling information is updated upon completion of SCSI commands.
 A data structure is allocated and zeroed when the host adapter is
 attached. So, if the driver is a module, the profile counters are
 cleared each time the driver is loaded.  The "clearprof" command
 allows you to clear these counters at any time.
 
 The following counters are available:
 
 ("num" prefix means "number of",
 "ms" means milli-seconds)
 
 num_trans
         Number of completed commands
         Example above: 18014 completed commands
 
 num_kbytes
         Number of kbytes transferred
         Example above: 671 MB transferred
 
 num_disc
         Number of SCSI disconnections
         Example above: 25763 SCSI disconnections
 
 num_break
         number of script interruptions (phase mismatch)
         Example above: 1673 script interruptions
 
 num_int
         Number of interrupts other than "on the fly"
         Example above: 1685 interruptions not "on the fly"
 
 num_fly
         Number of interrupts "on the fly"
         Example above: 18038 interruptions "on the fly"
 
 ms_setup
         Elapsed time for SCSI commands setups
         Example above: 4.94 seconds
 
 ms_data
         Elapsed time for data transfers
         Example above: 369.94 seconds spent for data transfer
 
 ms_disc
         Elapsed time for SCSI disconnections
         Example above: 183.09 seconds spent disconnected
 
 ms_post
         Elapsed time for command post processing
         (time from SCSI status get to command completion call)
         Example above: 1.32 seconds spent for post processing
 
 Due to the 1/100 second tick of the system clock, "ms_post" time may
 be wrong.
 
 In the example above, we got 18038 interrupts "on the fly" and only
 1673 script breaks generally due to disconnections inside a segment
 of the scatter list.
 
 
 8. Control commands
 ===================
 
 Control commands can be sent to the driver with write operations to
 the proc SCSI file system. The generic command syntax is the
 following::
 
       echo "<verb> <parameters>" >/proc/scsi/ncr53c8xx/0
       (assumes controller number is 0)
 
 Using "all" for "<target>" parameter with the commands below will
 apply to all targets of the SCSI chain (except the controller).
 
 Available commands:
 
 8.1 Set minimum synchronous period factor
 -----------------------------------------
 
     setsync <target> <period factor>
 
     :target:   target number
     :period:   minimum synchronous period.
                Maximum speed = 1000/(4*period factor) except for special
                cases below.
 
     Specify a period of 255, to force asynchronous transfer mode.
 
       - 10 means 25 nano-seconds synchronous period
       - 11 means 30 nano-seconds synchronous period
       - 12 means 50 nano-seconds synchronous period
 
 8.2 Set wide size
 -----------------
 
     setwide <target> <size>
 
     :target:   target number
     :size:     0=8 bits, 1=16bits
 
 8.3 Set maximum number of concurrent tagged commands
 ----------------------------------------------------
 
     settags <target> <tags>
 
     :target:   target number
     :tags:     number of concurrent tagged commands
                must not be greater than SCSI_NCR_MAX_TAGS (default: 8)
 
 8.4 Set order type for tagged command
 -------------------------------------
 
     setorder <order>
 
     :order:    3 possible values:
 
                simple:
                         use SIMPLE TAG for all operations (read and write)
 
                ordered:
                         use ORDERED TAG for all operations
 
                default:
                         use default tag type,
                         SIMPLE  TAG for read  operations
                         ORDERED TAG for write operations
 
 
 8.5 Set debug mode
 ------------------
 
     setdebug <list of debug flags>
 
     Available debug flags:
 
         ======== ========================================================
         alloc    print info about memory allocations (ccb, lcb)
         queue    print info about insertions into the command start queue
         result   print sense data on CHECK CONDITION status
         scatter  print info about the scatter process
         scripts  print info about the script binding process
         tiny     print minimal debugging information
         timing   print timing information of the NCR chip
         nego     print information about SCSI negotiations
         phase    print information on script interruptions
         ======== ========================================================
 
     Use "setdebug" with no argument to reset debug flags.
 
 
 8.6 Clear profile counters
 --------------------------
 
     clearprof
 
     The profile counters are automatically cleared when the amount of
     data transferred reaches 1000 GB in order to avoid overflow.
     The "clearprof" command allows you to clear these counters at any time.
 
 
 8.7 Set flag (no_disc)
 ----------------------
 
     setflag <target> <flag>
 
     target:    target number
 
     For the moment, only one flag is available:
 
         no_disc:   not allow target to disconnect.
 
     Do not specify any flag in order to reset the flag. For example:
 
     setflag 4
       will reset no_disc flag for target 4, so will allow it disconnections.
 
     setflag all
       will allow disconnection for all devices on the SCSI bus.
 
 
 8.8 Set verbose level
 ---------------------
 
     setverbose #level
 
     The driver default verbose level is 1. This command allows to change
     th driver verbose level after boot-up.
 
 8.9 Reset all logical units of a target
 ---------------------------------------
 
     resetdev <target>
 
     :target:   target number
 
     The driver will try to send a BUS DEVICE RESET message to the target.
     (Only supported by the SYM53C8XX driver and provided for test purpose)
 
 8.10 Abort all tasks of all logical units of a target
 -----------------------------------------------------
 
     cleardev <target>
 
     :target:   target number
 
     The driver will try to send a ABORT message to all the logical units
     of the target.
 
     (Only supported by the SYM53C8XX driver and provided for test purpose)
 
 
 9. Configuration parameters
 ===========================
 
 If the firmware of all your devices is perfect enough, all the
 features supported by the driver can be enabled at start-up.  However,
 if only one has a flaw for some SCSI feature, you can disable the
 support by the driver of this feature at linux start-up and enable
 this feature after boot-up only for devices that support it safely.
 
 CONFIG_SCSI_NCR53C8XX_IOMAPPED       (default answer: n)
     Answer "y" if you suspect your mother board to not allow memory mapped I/O.
 
     May slow down performance a little.  This option is required by
     Linux/PPC and is used no matter what you select here.  Linux/PPC
     suffers no performance loss with this option since all IO is memory
     mapped anyway.
 
 CONFIG_SCSI_NCR53C8XX_DEFAULT_TAGS    (default answer: 8)
     Default tagged command queue depth.
 
 CONFIG_SCSI_NCR53C8XX_MAX_TAGS         (default answer: 8)
     This option allows you to specify the maximum number of tagged commands
     that can be queued to a device. The maximum supported value is 32.
 
 CONFIG_SCSI_NCR53C8XX_SYNC            (default answer: 5)
     This option allows you to specify the frequency in MHz the driver
     will use at boot time for synchronous data transfer negotiations.
     This frequency can be changed later with the "setsync" control command.
     0 means "asynchronous data transfers".
 
 CONFIG_SCSI_NCR53C8XX_FORCE_SYNC_NEGO (default answer: n)
     Force synchronous negotiation for all SCSI-2 devices.
 
     Some SCSI-2 devices do not report this feature in byte 7 of inquiry
     response but do support it properly (TAMARACK scanners for example).
 
 CONFIG_SCSI_NCR53C8XX_NO_DISCONNECT   (default and only reasonable answer: n)
     If you suspect a device of yours does not properly support disconnections,
     you can answer "y". Then, all SCSI devices will never disconnect the bus
     even while performing long SCSI operations.
 
 CONFIG_SCSI_NCR53C8XX_SYMBIOS_COMPAT
     Genuine SYMBIOS boards use GPIO0 in output for controller LED and GPIO3
     bit as a flag indicating singled-ended/differential interface.
     If all the boards of your system are genuine SYMBIOS boards or use
     BIOS and drivers from SYMBIOS, you would want to enable this option.
 
     This option must NOT be enabled if your system has at least one 53C8XX
     based scsi board with a vendor-specific BIOS.
     For example, Tekram DC-390/U, DC-390/W and DC-390/F scsi controllers
     use a vendor-specific BIOS and are known to not use SYMBIOS compatible
     GPIO wiring. So, this option must not be enabled if your system has
     such a board installed.
 
 CONFIG_SCSI_NCR53C8XX_NVRAM_DETECT
     Enable support for reading the serial NVRAM data on Symbios and
     some Symbios compatible cards, and Tekram DC390W/U/F cards. Useful for
     systems with more than one Symbios compatible controller where at least
     one has a serial NVRAM, or for a system with a mixture of Symbios and
     Tekram cards. Enables setting the boot order of host adaptors
     to something other than the default order or "reverse probe" order.
     Also enables Symbios and Tekram cards to be distinguished so
     CONFIG_SCSI_NCR53C8XX_SYMBIOS_COMPAT may be set in a system with a
     mixture of Symbios and Tekram cards so the Symbios cards can make use of
     the full range of Symbios features, differential, led pin, without
     causing problems for the Tekram card(s).
 
 10. Boot setup commands
 =======================
 
 10.1 Syntax
 -----------
 
 Setup commands can be passed to the driver either at boot time or as a
 string variable using 'insmod'.
 
 A boot setup command for the ncr53c8xx (sym53c8xx) driver begins with the
 driver name "ncr53c8xx="(sym53c8xx). The kernel syntax parser then expects
 an optional list of integers separated with comma followed by an optional
 list of comma-separated strings. Example of boot setup command under lilo
 prompt::
 
     lilo: linux root=/dev/hda2 ncr53c8xx=tags:4,sync:10,debug:0x200
 
 - enable tagged commands, up to 4 tagged commands queued.
 - set synchronous negotiation speed to 10 Mega-transfers / second.
 - set DEBUG_NEGO flag.
 
 Since comma seems not to be allowed when defining a string variable using
 'insmod', the driver also accepts <space> as option separator.
 The following command will install driver module with the same options as
 above::
 
     insmod ncr53c8xx.o ncr53c8xx="tags:4 sync:10 debug:0x200"
 
 For the moment, the integer list of arguments is discarded by the driver.
 It will be used in the future in order to allow a per controller setup.
 
 Each string argument must be specified as "keyword:value". Only lower-case
 characters and digits are allowed.
 
 In a system that contains multiple 53C8xx adapters insmod will install the
 specified driver on each adapter. To exclude a chip use the 'excl' keyword.
 
 The sequence of commands::
 
     insmod sym53c8xx sym53c8xx=excl:0x1400
     insmod ncr53c8xx
 
 installs the sym53c8xx driver on all adapters except the one at IO port
 address 0x1400 and then installs the ncr53c8xx driver to the adapter at IO
 port address 0x1400.
 
 
 10.2 Available arguments
 ------------------------
 
 10.2.1  Master parity checking
 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
         ======     ========
         mpar:y     enabled
         mpar:n     disabled
         ======     ========
 
 10.2.2  Scsi parity checking
 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
         ======     ========
         spar:y     enabled
         spar:n     disabled
         ======     ========
 
 10.2.3  Scsi disconnections
 ^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
         ======     ========
         disc:y     enabled
         disc:n     disabled
         ======     ========
 
 10.2.4  Special features
 ^^^^^^^^^^^^^^^^^^^^^^^^
 
    Only apply to 810A, 825A, 860, 875 and 895 controllers.
    Have no effect with other ones.
 
         =======    =================================================
         specf:y    (or 1) enabled
         specf:n    (or 0) disabled
         specf:3           enabled except Memory Write And Invalidate
         =======    =================================================
 
    The default driver setup is 'specf:3'. As a consequence, option 'specf:y'
    must be specified in the boot setup command to enable Memory Write And
    Invalidate.
 
 10.2.5  Ultra SCSI support
 ^^^^^^^^^^^^^^^^^^^^^^^^^^
 
    Only apply to 860, 875, 895, 895a, 896, 1010 and 1010_66 controllers.
    Have no effect with other ones.
 
         =======    ========================
         ultra:n    All ultra speeds enabled
         ultra:2    Ultra2 enabled
         ultra:1    Ultra enabled
         ultra:0    Ultra speeds disabled
         =======    ========================
 
 10.2.6  Default number of tagged commands
 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
         ======================= ===============================
         tags:0     (or tags:1 ) tagged command queuing disabled
         tags:#tags (#tags  > 1) tagged command queuing enabled
         ======================= ===============================
 
   #tags will be truncated to the max queued commands configuration parameter.
   This option also allows to specify a command queue depth for each device
   that support tagged command queueing.
 
   Example::
 
       ncr53c8xx=tags:10/t2t3q16-t5q24/t1u2q32
 
   will set devices queue depth as follow:
 
       - controller #0 target #2 and target #3                  -> 16 commands,
       - controller #0 target #5                                -> 24 commands,
       - controller #1 target #1 logical unit #2                -> 32 commands,
       - all other logical units (all targets, all controllers) -> 10 commands.
 
 10.2.7  Default synchronous period factor
 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 ============ ========================================================
 sync:255     disabled (asynchronous transfer mode)
 sync:#factor
              ============     =======================================
              #factor = 10     Ultra-2 SCSI 40 Mega-transfers / second
              #factor = 11     Ultra-2 SCSI 33 Mega-transfers / second
              #factor < 25     Ultra   SCSI 20 Mega-transfers / second
              #factor < 50     Fast    SCSI-2
              ============     =======================================
 ============ ========================================================
 
   In all cases, the driver will use the minimum transfer period supported by
   controllers according to NCR53C8XX chip type.
 
 10.2.8  Negotiate synchronous with all devices
 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
         (force sync nego)
 
         =====      =========
         fsn:y      enabled
         fsn:n      disabled
         =====      =========
 
 10.2.9  Verbosity level
 ^^^^^^^^^^^^^^^^^^^^^^^
 
         ======     =========
         verb:0     minimal
         verb:1     normal
         verb:2     too much
         ======     =========
 
 10.2.10 Debug mode
 ^^^^^^^^^^^^^^^^^^
 
 ========   ==================================================================
 debug:0    clear debug flags
 debug:#x   set debug flags
 
             #x is an integer value combining the following power-of-2 values:
 
             =============  ======
             DEBUG_ALLOC       0x1
             DEBUG_PHASE       0x2
             DEBUG_POLL        0x4
             DEBUG_QUEUE       0x8
             DEBUG_RESULT     0x10
             DEBUG_SCATTER    0x20
             DEBUG_SCRIPT     0x40
             DEBUG_TINY       0x80
             DEBUG_TIMING    0x100
             DEBUG_NEGO      0x200
             DEBUG_TAGS      0x400
             DEBUG_FREEZE    0x800
             DEBUG_RESTART  0x1000
             =============  ======
 ========   ==================================================================
 
   You can play safely with DEBUG_NEGO. However, some of these flags may
   generate bunches of syslog messages.
 
 10.2.11 Burst max
 ^^^^^^^^^^^^^^^^^
 
 =========  ==================================================================
 burst:0    burst disabled
 burst:255  get burst length from initial IO register settings.
 burst:#x   burst enabled (1<<#x burst transfers max)
 
            #x is an integer value which is log base 2 of the burst transfers
            max.
 
            The NCR53C875 and NCR53C825A support up to 128 burst transfers
            (#x = 7).
 
            Other chips only support up to 16 (#x = 4).
 
            This is a maximum value. The driver set the burst length according
            to chip and revision ids. By default the driver uses the maximum
            value supported by the chip.
 =========  ==================================================================
 
 10.2.12 LED support
 ^^^^^^^^^^^^^^^^^^^
 
         =====      ===================
         led:1      enable  LED support
         led:0      disable LED support
         =====      ===================
 
   Donnot enable LED support if your scsi board does not use SDMS BIOS.
   (See 'Configuration parameters')
 
 10.2.13 Max wide
 ^^^^^^^^^^^^^^^^
 
         ======     ===================
         wide:1      wide scsi enabled
         wide:0      wide scsi disabled
         ======     ===================
 
   Some scsi boards use a 875 (ultra wide) and only supply narrow connectors.
   If you have connected a wide device with a 50 pins to 68 pins cable
   converter, any accepted wide negotiation will break further data transfers.
   In such a case, using "wide:0" in the bootup command will be helpful.
 
 10.2.14 Differential mode
 ^^^^^^^^^^^^^^^^^^^^^^^^^
 
         ======  =================================
         diff:0  never set up diff mode
         diff:1  set up diff mode if BIOS set it
         diff:2  always set up diff mode
         diff:3  set diff mode if GPIO3 is not set
         ======  =================================
 
 10.2.15 IRQ mode
 ^^^^^^^^^^^^^^^^
 
         =========  ========================================================
         irqm:0     always open drain
         irqm:1     same as initial settings (assumed BIOS settings)
         irqm:2     always totem pole
         irqm:0x10  driver will not use IRQF_SHARED flag when requesting irq
         =========  ========================================================
 
     (Bits 0x10 and 0x20 can be combined with hardware irq mode option)
 
 10.2.16 Reverse probe
 ^^^^^^^^^^^^^^^^^^^^^
 
         =========   ========================================================
         revprob:n   probe chip ids from the PCI configuration in this order:
                     810, 815, 820, 860, 875, 885, 895, 896
         revprob:y   probe chip ids in the reverse order.
         =========   ========================================================
 
 10.2.17 Fix up PCI configuration space
 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
         pcifix:<option bits>
 
     Available option bits:
 
         ===    ===============================================================
         0x0    No attempt to fix PCI configuration space registers values.
         0x1    Set PCI cache-line size register if not set.
         0x2    Set write and invalidate bit in PCI command register.
         0x4    Increase if necessary PCI latency timer according to burst max.
         ===    ===============================================================
 
     Use 'pcifix:7' in order to allow the driver to fix up all PCI features.
 
 10.2.18 Serial NVRAM
 ^^^^^^^^^^^^^^^^^^^^
 
         =======     =========================================
         nvram:n     do not look for serial NVRAM
         nvram:y     test controllers for onboard serial NVRAM
         =======     =========================================
 
         (alternate binary form)
         mvram=<bits options>
 
         ====   =================================================================
         0x01   look for NVRAM  (equivalent to nvram=y)
         0x02   ignore NVRAM "Synchronous negotiation" parameters for all devices
         0x04   ignore NVRAM "Wide negotiation"  parameter for all devices
         0x08   ignore NVRAM "Scan at boot time" parameter for all devices
         0x80   also attach controllers set to OFF in the NVRAM (sym53c8xx only)
         ====   =================================================================
 
 10.2.19 Check SCSI BUS
 ^^^^^^^^^^^^^^^^^^^^^^
 
         buschk:<option bits>
 
     Available option bits:
 
         ====   ================================================
         0x0:   No check.
         0x1:   Check and do not attach the controller on error.
         0x2:   Check and just warn on error.
         0x4:   Disable SCSI bus integrity checking.
         ====   ================================================
 
 10.2.20 Exclude a host from being attached
 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
         excl=<io_address>
 
     Prevent host at a given io address from being attached.
     For example 'ncr53c8xx=excl:0xb400,excl:0xc000' indicate to the
     ncr53c8xx driver not to attach hosts at address 0xb400 and 0xc000.
 
 10.2.21 Suggest a default SCSI id for hosts
 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
         ==========      ==========================================
         hostid:255      no id suggested.
         hostid:#x       (0 < x < 7) x suggested for hosts SCSI id.
         ==========      ==========================================
 
     If a host SCSI id is available from the NVRAM, the driver will ignore
     any value suggested as boot option. Otherwise, if a suggested value
     different from 255 has been supplied, it will use it. Otherwise, it will
     try to deduce the value previously set in the hardware and use value
     7 if the hardware value is zero.
 
 10.2.22 Enable use of IMMEDIATE ARBITRATION
 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
         (only supported by the sym53c8xx driver. See 10.7 for more details)
 
 =======   =================================================================
 iarb:0    do not use this feature.
 iarb:#x   use this feature according to bit fields as follow:
 
           ========= =======================================================
           bit 0 (1) enable IARB each time the initiator has been reselected
                     when it arbitrated for the SCSI BUS.
           (#x >> 4) maximum number of successive settings of IARB if the
                     initiator win arbitration and it has other commands
                     to send to a device.
           ========= =======================================================
 =======   =================================================================
 
 Boot fail safe
     safe:y      load the following assumed fail safe initial setup
 
   ========================      ======================  ==========
   master parity                 disabled                mpar:n
   scsi parity                   enabled                 spar:y
   disconnections                not allowed             disc:n
   special features              disabled                specf:n
   ultra scsi                    disabled                ultra:n
   force sync negotiation        disabled                fsn:n
   reverse probe                 disabled                revprob:n
   PCI fix up                    disabled                pcifix:0
   serial NVRAM                  enabled                 nvram:y
   verbosity level               2                       verb:2
   tagged command queuing        disabled                tags:0
   synchronous negotiation       disabled                sync:255
   debug flags                   none                    debug:0
   burst length                  from BIOS settings      burst:255
   LED support                   disabled                led:0
   wide support                  disabled                wide:0
   settle time                   10 seconds              settle:10
   differential support          from BIOS settings      diff:1
   irq mode                      from BIOS settings      irqm:1
   SCSI BUS check                do not attach on error  buschk:1
   immediate arbitration         disabled                iarb:0
   ========================      ======================  ==========
 
 10.3 Advised boot setup commands
 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 If the driver has been configured with default options, the equivalent
 boot setup is::
 
    ncr53c8xx=mpar:y,spar:y,disc:y,specf:3,fsn:n,ultra:2,fsn:n,revprob:n,verb:1\
              tags:0,sync:50,debug:0,burst:7,led:0,wide:1,settle:2,diff:0,irqm:0
 
 For an installation diskette or a safe but not fast system,
 boot setup can be::
 
     ncr53c8xx=safe:y,mpar:y,disc:y
     ncr53c8xx=safe:y,disc:y
     ncr53c8xx=safe:y,mpar:y
     ncr53c8xx=safe:y
 
 My personal system works flawlessly with the following equivalent setup::
 
    ncr53c8xx=mpar:y,spar:y,disc:y,specf:1,fsn:n,ultra:2,fsn:n,revprob:n,verb:1\
              tags:32,sync:12,debug:0,burst:7,led:1,wide:1,settle:2,diff:0,irqm:0
 
 The driver prints its actual setup when verbosity level is 2. You can try
 "ncr53c8xx=verb:2" to get the "static" setup of the driver, or add "verb:2"
 to your boot setup command in order to check the actual setup the driver is
 using.
 
 10.4 PCI configuration fix-up boot option
 -----------------------------------------
 
 pcifix:<option bits>
 
 Available option bits:
 
     ===      =====================================================
     0x1      Set PCI cache-line size register if not set.
     0x2      Set write and invalidate bit in PCI command register.
     ===      =====================================================
 
 Use 'pcifix:3' in order to allow the driver to fix both PCI features.
 
 These options only apply to new SYMBIOS chips 810A, 825A, 860, 875
 and 895 and are only supported for Pentium and 486 class processors.
 Recent SYMBIOS 53C8XX scsi processors are able to use PCI read multiple
 and PCI write and invalidate commands. These features require the
 cache line size register to be properly set in the PCI configuration
 space of the chips. On the other hand, chips will use PCI write and
 invalidate commands only if the corresponding bit is set to 1 in the
 PCI command register.
 
 Not all PCI bioses set the PCI cache line register and the PCI write and
 invalidate bit in the PCI configuration space of 53C8XX chips.
 Optimized PCI accesses may be broken for some PCI/memory controllers or
 make problems with some PCI boards.
 
 This fix-up worked flawlessly on my previous system.
 (MB Triton HX / 53C875 / 53C810A)
 I use these options at my own risks as you will do if you decide to
 use them too.
 
 
 10.5 Serial NVRAM support boot option
 -------------------------------------
 
 =======     =========================================
 nvram:n     do not look for serial NVRAM
 nvram:y     test controllers for onboard serial NVRAM
 =======     =========================================
 
 This option can also been entered as an hexadecimal value that allows
 to control what information the driver will get from the NVRAM and what
 information it will ignore.
 For details see '17. Serial NVRAM support'.
 
 When this option is enabled, the driver tries to detect all boards using
 a Serial NVRAM. This memory is used to hold user set up parameters.
 
 The parameters the driver is able to get from the NVRAM depend on the
 data format used, as follow:
 
 +-------------------------------+------------------+--------------+
 |                               |Tekram format     |Symbios format|
 +-------------------------------+------------------+--------------+
 |General and host parameters    |                  |              |
 +-------------------------------+------------------+--------------+
 |  * Boot order                 |        N         |       Y      |
 +-------------------------------+------------------+--------------+
 |  * Host SCSI ID               |        Y         |       Y      |
 +-------------------------------+------------------+--------------+
 |  * SCSI parity checking       |        Y         |       Y      |
 +-------------------------------+------------------+--------------+
 |  * Verbose boot messages      |        N         |       Y      |
 +-------------------------------+------------------+--------------+
 |SCSI devices parameters                                          |
 +-------------------------------+------------------+--------------+
 |  * Synchronous transfer speed |        Y         |       Y      |
 +-------------------------------+------------------+--------------+
 |  * Wide 16 / Narrow           |        Y         |       Y      |
 +-------------------------------+------------------+--------------+
 |  * Tagged Command Queuing     |        Y         |       Y      |
 |    enabled                    |                  |              |
 +-------------------------------+------------------+--------------+
 |  * Disconnections enabled     |        Y         |       Y      |
 +-------------------------------+------------------+--------------+
 |  * Scan at boot time          |        N         |       Y      |
 +-------------------------------+------------------+--------------+
 
 In order to speed up the system boot, for each device configured without
 the "scan at boot time" option, the driver forces an error on the
 first TEST UNIT READY command received for this device.
 
 Some SDMS BIOS revisions seem to be unable to boot cleanly with very fast
 hard disks. In such a situation you cannot configure the NVRAM with
 optimized parameters value.
 
 The 'nvram' boot option can be entered in hexadecimal form in order
 to ignore some options configured in the NVRAM, as follow:
 
 mvram=<bits options>
 
       ====   =================================================================
       0x01   look for NVRAM  (equivalent to nvram=y)
       0x02   ignore NVRAM "Synchronous negotiation" parameters for all devices
       0x04   ignore NVRAM "Wide negotiation"  parameter for all devices
       0x08   ignore NVRAM "Scan at boot time" parameter for all devices
       0x80   also attach controllers set to OFF in the NVRAM (sym53c8xx only)
       ====   =================================================================
 
 Option 0x80 is only supported by the sym53c8xx driver and is disabled by
 default. Result is that, by default (option not set), the sym53c8xx driver
 will not attach controllers set to OFF in the NVRAM.
 
 The ncr53c8xx always tries to attach all the controllers. Option 0x80 has
 not been added to the ncr53c8xx driver, since it has been reported to
 confuse users who use this driver since a long time. If you desire a
 controller not to be attached by the ncr53c8xx driver at Linux boot, you
 must use the 'excl' driver boot option.
 
 10.6 SCSI BUS checking boot option.
 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 When this option is set to a non-zero value, the driver checks SCSI lines
 logic state, 100 micro-seconds after having asserted the SCSI RESET line.
 The driver just reads SCSI lines and checks all lines read FALSE except RESET.
 Since SCSI devices shall release the BUS at most 800 nano-seconds after SCSI
 RESET has been asserted, any signal to TRUE may indicate a SCSI BUS problem.
 Unfortunately, the following common SCSI BUS problems are not detected:
 
 - Only 1 terminator installed.
 - Misplaced terminators.
 - Bad quality terminators.
 
 On the other hand, either bad cabling, broken devices, not conformant
 devices, ... may cause a SCSI signal to be wrong when te driver reads it.
 
 10.7 IMMEDIATE ARBITRATION boot option
 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 This option is only supported by the SYM53C8XX driver (not by the NCR53C8XX).
 
 SYMBIOS 53C8XX chips are able to arbitrate for the SCSI BUS as soon as they
 have detected an expected disconnection (BUS FREE PHASE). For this process
 to be started, bit 1 of SCNTL1 IO register must be set when the chip is
 connected to the SCSI BUS.
 
 When this feature has been enabled for the current connection, the chip has
 every chance to win arbitration if only devices with lower priority are
 competing for the SCSI BUS. By the way, when the chip is using SCSI id 7,
 then it will for sure win the next SCSI BUS arbitration.
 
 Since, there is no way to know what devices are trying to arbitrate for the
 BUS, using this feature can be extremely unfair. So, you are not advised
 to enable it, or at most enable this feature for the case the chip lost
 the previous arbitration (boot option 'iarb:1').
 
 This feature has the following advantages:
 
 a) Allow the initiator with ID 7 to win arbitration when it wants so.
 b) Overlap at least 4 micro-seconds of arbitration time with the execution
    of SCRIPTS that deal with the end of the current connection and that
    starts the next job.
 
 Hmmm... But (a) may just prevent other devices from reselecting the initiator,
 and delay data transfers or status/completions, and (b) may just waste
 SCSI BUS bandwidth if the SCRIPTS execution lasts more than 4 micro-seconds.
 
 The use of IARB needs the SCSI_NCR_IARB_SUPPORT option to have been defined
 at compile time and the 'iarb' boot option to have been set to a non zero
 value at boot time. It is not that useful for real work, but can be used
 to stress SCSI devices or for some applications that can gain advantage of
 it. By the way, if you experience badnesses like 'unexpected disconnections',
 'bad reselections', etc... when using IARB on heavy IO load, you should not
 be surprised, because force-feeding anything and blocking its arse at the
 same time cannot work for a long time. :-))
 
 
 11. Some constants and flags of the ncr53c8xx.h header file
 ===========================================================
 
 Some of these are defined from the configuration parameters.  To
 change other "defines", you must edit the header file.  Do that only
 if you know what you are doing.
 
 SCSI_NCR_SETUP_SPECIAL_FEATURES (default: defined)
         If defined, the driver will enable some special features according
         to chip and revision id.
 
         For 810A, 860, 825A, 875 and 895 scsi chips, this option enables
         support of features that reduce load of PCI bus and memory accesses
         during  scsi transfer processing: burst op-code fetch, read multiple,
         read line, prefetch, cache line, write and invalidate,
         burst 128 (875 only), large dma fifo (875 only), offset 16 (875 only).
         Can be changed by the following boot setup command::
 
                 ncr53c8xx=specf:n
 
 SCSI_NCR_IOMAPPED               (default: not defined)
         If defined, normal I/O is forced.
 
 SCSI_NCR_SHARE_IRQ              (default: defined)
         If defined, request shared IRQ.
 
 SCSI_NCR_MAX_TAGS               (default: 8)
         Maximum number of simultaneous tagged commands to a device.
 
         Can be changed by "settags <target> <maxtags>"
 
 SCSI_NCR_SETUP_DEFAULT_SYNC     (default: 50)
         Transfer period factor the driver will use at boot time for synchronous
         negotiation. 0 means asynchronous.
 
         Can be changed by "setsync <target> <period factor>"
 
 SCSI_NCR_SETUP_DEFAULT_TAGS     (default: 8)
         Default number of simultaneous tagged commands to a device.
 
         < 1 means tagged command queuing disabled at start-up.
 
 SCSI_NCR_ALWAYS_SIMPLE_TAG      (default: defined)
         Use SIMPLE TAG for read and write commands.
 
         Can be changed by "setorder <ordered|simple|default>"
 
 SCSI_NCR_SETUP_DISCONNECTION    (default: defined)
         If defined, targets are allowed to disconnect.
 
 SCSI_NCR_SETUP_FORCE_SYNC_NEGO  (default: not defined)
         If defined, synchronous negotiation is tried for all SCSI-2 devices.
 
         Can be changed by "setsync <target> <period>"
 
 SCSI_NCR_SETUP_MASTER_PARITY    (default: defined)
         If defined, master parity checking is enabled.
 
 SCSI_NCR_SETUP_SCSI_PARITY      (default: defined)
         If defined, SCSI parity checking is enabled.
 
 SCSI_NCR_PROFILE_SUPPORT        (default: not defined)
         If defined, profiling information is gathered.
 
 SCSI_NCR_MAX_SCATTER            (default: 128)
         Scatter list size of the driver ccb.
 
 SCSI_NCR_MAX_TARGET             (default: 16)
         Max number of targets per host.
 
 SCSI_NCR_MAX_HOST               (default: 2)
         Max number of host controllers.
 
 SCSI_NCR_SETTLE_TIME            (default: 2)
         Number of seconds the driver will wait after reset.
 
 SCSI_NCR_TIMEOUT_ALERT          (default: 3)
         If a pending command will time out after this amount of seconds,
         an ordered tag is used for the next command.
 
         Avoids timeouts for unordered tagged commands.
 
 SCSI_NCR_CAN_QUEUE              (default: 7*SCSI_NCR_MAX_TAGS)
         Max number of commands that can be queued to a host.
 
 SCSI_NCR_CMD_PER_LUN            (default: SCSI_NCR_MAX_TAGS)
         Max number of commands queued to a host for a device.
 
 SCSI_NCR_SG_TABLESIZE           (default: SCSI_NCR_MAX_SCATTER-1)
         Max size of the Linux scatter/gather list.
 
 SCSI_NCR_MAX_LUN        (default: 8)
         Max number of LUNs per target.
 
 
 12. Installation
 ================
 
 This driver is part of the linux kernel distribution.
 Driver files are located in the sub-directory "drivers/scsi" of the
 kernel source tree.
 
 Driver files::
 
         README.ncr53c8xx        : this file
         ChangeLog.ncr53c8xx     : change log
         ncr53c8xx.h             : definitions
         ncr53c8xx.c             : the driver code
 
 New driver versions are made available separately in order to allow testing
 changes and new features prior to including them into the linux kernel
 distribution. The following URL provides information on latest available
 patches:
 
       ftp://ftp.tux.org/pub/people/gerard-roudier/README
 
 
 13. Architecture dependent features
 ===================================
 
 <Not yet written>
 
 
 14. Known problems
 ==================
 
 14.1 Tagged commands with Iomega Jaz device
 -------------------------------------------
 
 I have not tried this device, however it has been reported to me the
 following: This device is capable of Tagged command queuing. However
 while spinning up, it rejects Tagged commands. This behaviour is
 conforms to 6.8.2 of SCSI-2 specifications. The current behaviour of
 the driver in that situation is not satisfying. So do not enable
 Tagged command queuing for devices that are able to spin down.  The
 other problem that may appear is timeouts. The only way to avoid
 timeouts seems to edit linux/drivers/scsi/sd.c and to increase the
 current timeout values.
 
 14.2 Device names change when another controller is added
 ---------------------------------------------------------
 
 When you add a new NCR53C8XX chip based controller to a system that already
 has one or more controllers of this family, it may happen that the order
 the driver registers them to the kernel causes problems due to device
 name changes.
 When at least one controller uses NvRAM, SDMS BIOS version 4 allows you to
 define the order the BIOS will scan the scsi boards. The driver attaches
 controllers according to BIOS information if NvRAM detect option is set.
 
 If your controllers do not have NvRAM, you can:
 
 - Ask the driver to probe chip ids in reverse order from the boot command
   line: ncr53c8xx=revprob:y
 - Make appropriate changes in the fstab.
 - Use the 'scsidev' tool from Eric Youngdale.
 
 14.3 Using only 8 bit devices with a WIDE SCSI controller
 ---------------------------------------------------------
 
 When only 8 bit NARROW devices are connected to a 16 bit WIDE SCSI controller,
 you must ensure that lines of the wide part of the SCSI BUS are pulled-up.
 This can be achieved by ENABLING the WIDE TERMINATOR portion of the SCSI
 controller card.
 
 The TYAN 1365 documentation revision 1.2 is not correct about such settings.
 (page 10, figure 3.3).
 
 14.4 Possible data corruption during a Memory Write and Invalidate
 ------------------------------------------------------------------
 
 This problem is described in SYMBIOS DEL 397, Part Number 69-039241, ITEM 4.
 
 In some complex situations, 53C875 chips revision <= 3 may start a PCI
 Write and Invalidate Command at a not cache-line-aligned 4 DWORDS boundary.
 This is only possible when Cache Line Size is 8 DWORDS or greater.
 Pentium systems use a 8 DWORDS cache line size and so are concerned by
 this chip bug, unlike i486 systems that use a 4 DWORDS cache line size.
 
 When this situation occurs, the chip may complete the Write and Invalidate
 command after having only filled part of the last cache line involved in
 the transfer, leaving to data corruption the remainder of this cache line.
 
 Not using Write And Invalidate obviously gets rid of this chip bug, and so
 it is now the default setting of the driver.
 However, for people like me who want to enable this feature, I have added
 part of a work-around suggested by SYMBIOS. This work-around resets the
 addressing logic when the DATA IN phase is entered and so prevents the bug
 from being triggered for the first SCSI MOVE of the phase. This work-around
 should be enough according to the following:
 
 The only driver internal data structure that is greater than 8 DWORDS  and
 that is moved by the SCRIPTS processor is the 'CCB header' that contains
 the context of the SCSI transfer. This data structure is aligned on 8 DWORDS
 boundary (Pentium Cache Line Size), and so is immune to this chip bug, at
 least on Pentium systems.
 
 But the conditions of this bug can be met when a SCSI read command is
 performed using a buffer that is 4 DWORDS but not cache-line aligned.
 This cannot happen under Linux when scatter/gather lists are used since
 they only refer to system buffers that are well aligned. So, a work around
 may only be needed under Linux when a scatter/gather list is not used and
 when the SCSI DATA IN phase is reentered after a phase mismatch.
 
 15. SCSI problem troubleshooting
 ================================
 
 15.1 Problem tracking
 ---------------------
 
 Most SCSI problems are due to a non conformant SCSI bus or to buggy
 devices.  If unfortunately you have SCSI problems, you can check the
 following things:
 
 - SCSI bus cables
 - terminations at both end of the SCSI chain
 - linux syslog messages (some of them may help you)
 
 If you do not find the source of problems, you can configure the
 driver with no features enabled.
 
 - only asynchronous data transfers
 - tagged commands disabled
 - disconnections not allowed
 
 Now, if your SCSI bus is ok, your system have every chance to work
 with this safe configuration but performances will not be optimal.
 
 If it still fails, then you can send your problem description to
 appropriate mailing lists or news-groups.  Send me a copy in order to
 be sure I will receive it.  Obviously, a bug in the driver code is
 possible.
 
      My email address: Gerard Roudier <groudier@free.fr>
 
 Allowing disconnections is important if you use several devices on
 your SCSI bus but often causes problems with buggy devices.
 Synchronous data transfers increases throughput of fast devices like
 hard disks.  Good SCSI hard disks with a large cache gain advantage of
 tagged commands queuing.
 
 Try to enable one feature at a time with control commands.  For example:
 
 ::
 
     echo "setsync all 25" >/proc/scsi/ncr53c8xx/0
 
 Will enable fast synchronous data transfer negotiation for all targets.
 
 ::
 
     echo "setflag 3" >/proc/scsi/ncr53c8xx/0
 
 Will reset flags (no_disc) for target 3, and so will allow it to disconnect
 the SCSI Bus.
 
 ::
 
     echo "settags 3 8" >/proc/scsi/ncr53c8xx/0
 
 Will enable tagged command queuing for target 3 if that device supports it.
 
 Once you have found the device and the feature that cause problems, just
 disable that feature for that device.
 
 15.2 Understanding hardware error reports
 -----------------------------------------
 
 When the driver detects an unexpected error condition, it may display a
 message of the following pattern::
 
     sym53c876-0:1: ERROR (0:48) (1-21-65) (f/95) @ (script 7c0:19000000).
     sym53c876-0: script cmd = 19000000
     sym53c876-0: regdump: da 10 80 95 47 0f 01 07 75 01 81 21 80 01 09 00.
 
 Some fields in such a message may help you understand the cause of the
 problem, as follows::
 
     sym53c876-0:1: ERROR (0:48) (1-21-65) (f/95) @ (script 7c0:19000000).
     ............A.........B.C....D.E..F....G.H.......I.....J...K.......
 
 Field A : target number.
   SCSI ID of the device the controller was talking with at the moment the
   error occurs.
 
 Field B : DSTAT io register (DMA STATUS)
   ========   =============================================================
   Bit 0x40   MDPE Master Data Parity Error
              Data parity error detected on the PCI BUS.
   Bit 0x20   BF   Bus Fault
              PCI bus fault condition detected
   Bit 0x01   IID  Illegal Instruction Detected
              Set by the chip when it detects an Illegal Instruction format
              on some condition that makes an instruction illegal.
   Bit 0x80   DFE Dma Fifo Empty
              Pure status bit that does not indicate an error.
   ========   =============================================================
 
   If the reported DSTAT value contains a combination of MDPE (0x40),
   BF (0x20), then the cause may be likely due to a PCI BUS problem.
 
 Field C : SIST io register (SCSI Interrupt Status)
   ========   ==================================================================
   Bit 0x08   SGE  SCSI GROSS ERROR
              Indicates that the chip detected a severe error condition
              on the SCSI BUS that prevents the SCSI protocol from functioning
              properly.
   Bit 0x04   UDC  Unexpected Disconnection
              Indicates that the device released the SCSI BUS when the chip
              was not expecting this to happen. A device may behave so to
              indicate the SCSI initiator that an error condition not reportable
              using the SCSI protocol has occurred.
   Bit 0x02   RST  SCSI BUS Reset
              Generally SCSI targets do not reset the SCSI BUS, although any
              device on the BUS can reset it at any time.
   Bit 0x01   PAR  Parity
              SCSI parity error detected.
   ========   ==================================================================
 
   On a faulty SCSI BUS, any error condition among SGE (0x08), UDC (0x04) and
   PAR (0x01) may be detected by the chip. If your SCSI system sometimes
   encounters such error conditions, especially SCSI GROSS ERROR, then a SCSI
   BUS problem is likely the cause of these errors.
 
 For fields D,E,F,G and H, you may look into the sym53c8xx_defs.h file
 that contains some minimal comments on IO register bits.
 
 Field D : SOCL  Scsi Output Control Latch
           This register reflects the state of the SCSI control lines the
           chip want to drive or compare against.
 
 Field E : SBCL  Scsi Bus Control Lines
           Actual value of control lines on the SCSI BUS.
 
 Field F : SBDL  Scsi Bus Data Lines
           Actual value of data lines on the SCSI BUS.
 
 Field G : SXFER  SCSI Transfer
           Contains the setting of the Synchronous Period for output and
           the current Synchronous offset (offset 0 means asynchronous).
 
 Field H : SCNTL3 Scsi Control Register 3
           Contains the setting of timing values for both asynchronous and
           synchronous data transfers.
 
 Understanding Fields I, J, K and dumps requires to have good knowledge of
 SCSI standards, chip cores functionnals and internal driver data structures.
 You are not required to decode and understand them, unless you want to help
 maintain the driver code.
 
 16. Synchronous transfer negotiation tables
 ===========================================
 
 Tables below have been created by calling the routine the driver uses
 for synchronisation negotiation timing calculation and chip setting.
 The first table corresponds to Ultra chips 53875 and 53C860 with 80 MHz
 clock and 5 clock divisors.
 The second one has been calculated by setting the scsi clock to 40 Mhz
 and using 4 clock divisors and so applies to all NCR53C8XX chips in fast
 SCSI-2 mode.
 
 Periods are in nano-seconds and speeds are in Mega-transfers per second.
 1 Mega-transfers/second means 1 MB/s with 8 bits SCSI and 2 MB/s with
 Wide16 SCSI.
 
 16.1 Synchronous timings for 53C895, 53C875 and 53C860 SCSI controllers
 
 +-----------------------------+--------+-------+--------------+
 |Negotiated                   |NCR settings    |              |
 +-------+--------+------------+--------+-------+              |
 |Factor |Period  |Speed       |Period  |Speed  |              |
 +-------+--------+------------+--------+-------+--------------+
 |10     | 25     |40.000      | 25     |40.000 | (53C895 only)|
 +-------+--------+------------+--------+-------+--------------+
 |11     | 30.2   |33.112      | 31.25  |32.000 | (53C895 only)|
 +-------+--------+------------+--------+-------+--------------+
 |12     | 50     |20.000      | 50     |20.000 |              |
 +-------+--------+------------+--------+-------+--------------+
 |13     | 52     |19.230      | 62     |16.000 |              |
 +-------+--------+------------+--------+-------+--------------+
 |14     | 56     |17.857      | 62     |16.000 |              |
 +-------+--------+------------+--------+-------+--------------+
 |15     | 60     |16.666      | 62     |16.000 |              |
 +-------+--------+------------+--------+-------+--------------+
 |16     | 64     |15.625      | 75     |13.333 |              |
 +-------+--------+------------+--------+-------+--------------+
 |17     | 68     |14.705      | 75     |13.333 |              |
 +-------+--------+------------+--------+-------+--------------+
 |18     | 72     |13.888      | 75     |13.333 |              |
 +-------+--------+------------+--------+-------+--------------+
 |19     | 76     |13.157      | 87     |11.428 |              |
 +-------+--------+------------+--------+-------+--------------+
 |20     | 80     |12.500      | 87     |11.428 |              |
 +-------+--------+------------+--------+-------+--------------+
 |21     | 84     |11.904      | 87     |11.428 |              |
 +-------+--------+------------+--------+-------+--------------+
 |22     | 88     |11.363      | 93     |10.666 |              |
 +-------+--------+------------+--------+-------+--------------+
 |23     | 92     |10.869      | 93     |10.666 |              |
 +-------+--------+------------+--------+-------+--------------+
 |24     | 96     |10.416      |100     |10.000 |              |
 +-------+--------+------------+--------+-------+--------------+
 |25     |100     |10.000      |100     |10.000 |              |
 +-------+--------+------------+--------+-------+--------------+
 |26     |104     | 9.615      |112     | 8.888 |              |
 +-------+--------+------------+--------+-------+--------------+
 |27     |108     | 9.259      |112     | 8.888 |              |
 +-------+--------+------------+--------+-------+--------------+
 |28     |112     | 8.928      |112     | 8.888 |              |
 +-------+--------+------------+--------+-------+--------------+
 |29     |116     | 8.620      |125     | 8.000 |              |
 +-------+--------+------------+--------+-------+--------------+
 |30     |120     | 8.333      |125     | 8.000 |              |
 +-------+--------+------------+--------+-------+--------------+
 |31     |124     | 8.064      |125     | 8.000 |              |
 +-------+--------+------------+--------+-------+--------------+
 |32     |128     | 7.812      |131     | 7.619 |              |
 +-------+--------+------------+--------+-------+--------------+
 |33     |132     | 7.575      |150     | 6.666 |              |
 +-------+--------+------------+--------+-------+--------------+
 |34     |136     | 7.352      |150     | 6.666 |              |
 +-------+--------+------------+--------+-------+--------------+
 |35     |140     | 7.142      |150     | 6.666 |              |
 +-------+--------+------------+--------+-------+--------------+
 |36     |144     | 6.944      |150     | 6.666 |              |
 +-------+--------+------------+--------+-------+--------------+
 |37     |148     | 6.756      |150     | 6.666 |              |
 +-------+--------+------------+--------+-------+--------------+
 |38     |152     | 6.578      |175     | 5.714 |              |
 +-------+--------+------------+--------+-------+--------------+
 |39     |156     | 6.410      |175     | 5.714 |              |
 +-------+--------+------------+--------+-------+--------------+
 |40     |160     | 6.250      |175     | 5.714 |              |
 +-------+--------+------------+--------+-------+--------------+
 |41     |164     | 6.097      |175     | 5.714 |              |
 +-------+--------+------------+--------+-------+--------------+
 |42     |168     | 5.952      |175     | 5.714 |              |
 +-------+--------+------------+--------+-------+--------------+
 |43     |172     | 5.813      |175     | 5.714 |              |
 +-------+--------+------------+--------+-------+--------------+
 |44     |176     | 5.681      |187     | 5.333 |              |
 +-------+--------+------------+--------+-------+--------------+
 |45     |180     | 5.555      |187     | 5.333 |              |
 +-------+--------+------------+--------+-------+--------------+
 |46     |184     | 5.434      |187     | 5.333 |              |
 +-------+--------+------------+--------+-------+--------------+
 |47     |188     | 5.319      |200     | 5.000 |              |
 +-------+--------+------------+--------+-------+--------------+
 |48     |192     | 5.208      |200     | 5.000 |              |
 +-------+--------+------------+--------+-------+--------------+
 |49     |196     | 5.102      |200     | 5.000 |              |
 +-------+--------+------------+--------+-------+--------------+
 
 16.2 Synchronous timings for fast SCSI-2 53C8XX controllers
 
 +-----------------------------+----------------+
 |Negotiated                   |NCR settings    |
 +-------+--------+------------+--------+-------+
 |Factor |Period  |Speed       |Period  |Speed  |
 +-------+--------+------------+--------+-------+
 |25     |100     |10.000      |100     |10.000 |
 +-------+--------+------------+--------+-------+
 |26     |104     |9.615       |125     | 8.000 |
 +-------+--------+------------+--------+-------+
 |27     |108     |9.259       |125     | 8.000 |
 +-------+--------+------------+--------+-------+
 |28     |112     |8.928       |125     | 8.000 |
 +-------+--------+------------+--------+-------+
 |29     |116     |8.620       |125     | 8.000 |
 +-------+--------+------------+--------+-------+
 |30     |120     |8.333       |125     | 8.000 |
 +-------+--------+------------+--------+-------+
 |31     |124     |8.064       |125     | 8.000 |
 +-------+--------+------------+--------+-------+
 |32     |128     |7.812       |131     | 7.619 |
 +-------+--------+------------+--------+-------+
 |33     |132     |7.575       |150     | 6.666 |
 +-------+--------+------------+--------+-------+
 |34     |136     |7.352       |150     | 6.666 |
 +-------+--------+------------+--------+-------+
 |35     |140     |7.142       |150     | 6.666 |
 +-------+--------+------------+--------+-------+
 |36     |144     |6.944       |150     | 6.666 |
 +-------+--------+------------+--------+-------+
 |37     |148     |6.756       |150     | 6.666 |
 +-------+--------+------------+--------+-------+
 |38     |152     |6.578       |175     | 5.714 |
 +-------+--------+------------+--------+-------+
 |39     |156     |6.410       |175     | 5.714 |
 +-------+--------+------------+--------+-------+
 |40     |160     |6.250       |175     | 5.714 |
 +-------+--------+------------+--------+-------+
 |41     |164     |6.097       |175     | 5.714 |
 +-------+--------+------------+--------+-------+
 |42     |168     |5.952       |175     | 5.714 |
 +-------+--------+------------+--------+-------+
 |43     |172     |5.813       |175     | 5.714 |
 +-------+--------+------------+--------+-------+
 |44     |176     |5.681       |187     | 5.333 |
 +-------+--------+------------+--------+-------+
 |45     |180     |5.555       |187     | 5.333 |
 +-------+--------+------------+--------+-------+
 |46     |184     |5.434       |187     | 5.333 |
 +-------+--------+------------+--------+-------+
 |47     |188     |5.319       |200     | 5.000 |
 +-------+--------+------------+--------+-------+
 |48     |192     |5.208       |200     | 5.000 |
 +-------+--------+------------+--------+-------+
 |49     |196     |5.102       |200     | 5.000 |
 +-------+--------+------------+--------+-------+
 
 
 17. Serial NVRAM
 ================
 
 (added by Richard Waltham: dormouse@farsrobt.demon.co.uk)
 
 17.1 Features
 -------------
 
 Enabling serial NVRAM support enables detection of the serial NVRAM included
 on Symbios and some Symbios compatible host adaptors, and Tekram boards. The
 serial NVRAM is used by Symbios and Tekram to hold set up parameters for the
 host adaptor and its attached drives.
 
 The Symbios NVRAM also holds data on the boot order of host adaptors in a
 system with more than one host adaptor. This enables the order of scanning
 the cards for drives to be changed from the default used during host adaptor
 detection.
 
 This can be done to a limited extent at the moment using "reverse probe" but
 this only changes the order of detection of different types of cards. The
 NVRAM boot order settings can do this as well as change the order the same
 types of cards are scanned in, something "reverse probe" cannot do.
 
 Tekram boards using Symbios chips, DC390W/F/U, which have NVRAM are detected
 and this is used to distinguish between Symbios compatible and Tekram host
 adaptors. This is used to disable the Symbios compatible "diff" setting
 incorrectly set on Tekram boards if the CONFIG_SCSI_53C8XX_SYMBIOS_COMPAT
 configuration parameter is set enabling both Symbios and Tekram boards to be
 used together with the Symbios cards using all their features, including
 "diff" support. ("led pin" support for Symbios compatible cards can remain
 enabled when using Tekram cards. It does nothing useful for Tekram host
 adaptors but does not cause problems either.)
 
 
 17.2 Symbios NVRAM layout
 -------------------------
 
 typical data at NVRAM address 0x100 (53c810a NVRAM)::
 
     00 00
     64 01
     8e 0b
 
     00 30 00 00 00 00 07 00 00 00 00 00 00 00 07 04 10 04 00 00
 
     04 00 0f 00 00 10 00 50 00 00 01 00 00 62
     04 00 03 00 00 10 00 58 00 00 01 00 00 63
     04 00 01 00 00 10 00 48 00 00 01 00 00 61
     00 00 00 00 00 00 00 00 00 00 00 00 00 00
 
     0f 00 08 08 64 00 0a 00
     0f 00 08 08 64 00 0a 00
     0f 00 08 08 64 00 0a 00
     0f 00 08 08 64 00 0a 00
     0f 00 08 08 64 00 0a 00
     0f 00 08 08 64 00 0a 00
     0f 00 08 08 64 00 0a 00
     0f 00 08 08 64 00 0a 00
 
     0f 00 08 08 64 00 0a 00
     0f 00 08 08 64 00 0a 00
     0f 00 08 08 64 00 0a 00
     0f 00 08 08 64 00 0a 00
     0f 00 08 08 64 00 0a 00
     0f 00 08 08 64 00 0a 00
     0f 00 08 08 64 00 0a 00
     0f 00 08 08 64 00 0a 00
 
     00 00 00 00 00 00 00 00
     00 00 00 00 00 00 00 00
     00 00 00 00 00 00 00 00
     00 00 00 00 00 00 00 00
     00 00 00 00 00 00 00 00
     00 00 00 00 00 00 00 00
     00 00 00 00 00 00 00 00
     00 00 00 00 00 00 00 00
 
     00 00 00 00 00 00 00 00
     00 00 00 00 00 00 00 00
     00 00 00 00 00 00 00 00
     00 00 00 00 00 00 00 00
     00 00 00 00 00 00 00 00
     00 00 00 00 00 00 00 00
     00 00 00 00 00 00 00 00
     00 00 00 00 00 00 00 00
 
     00 00 00 00 00 00 00 00
     00 00 00 00 00 00 00 00
     00 00 00 00 00 00 00 00
 
     fe fe
     00 00
     00 00
 
 NVRAM layout details
 
 =============  ================
 NVRAM Address
 =============  ================
 0x000-0x0ff    not used
 0x100-0x26f    initialised data
 0x270-0x7ff    not used
 =============  ================
 
 general layout::
 
         header  -   6 bytes,
         data    - 356 bytes (checksum is byte sum of this data)
         trailer -   6 bytes
                   ---
         total     368 bytes
 
 data area layout::
 
         controller set up  -  20 bytes
         boot configuration -  56 bytes (4x14 bytes)
         device set up      - 128 bytes (16x8 bytes)
         unused (spare?)    - 152 bytes (19x8 bytes)
                              ---
         total                356 bytes
 
 header::
 
     00 00   - ?? start marker
     64 01   - byte count (lsb/msb excludes header/trailer)
     8e 0b   - checksum (lsb/msb excludes header/trailer)
 
 controller set up::
 
     00 30 00 00 00 00 07 00 00 00 00 00 00 00 07 04 10 04 00 00
                     |     |           |     |
                     |     |           |      -- host ID
                     |     |           |
                     |     |            --Removable Media Support
                     |     |               0x00 = none
                     |     |               0x01 = Bootable Device
                     |     |               0x02 = All with Media
                     |     |
                     |      --flag bits 2
                     |        0x00000001= scan order hi->low
                     |            (default 0x00 - scan low->hi)
                         --flag bits 1
                         0x00000001 scam enable
                         0x00000010 parity enable
                         0x00000100 verbose boot msgs
 
 remaining bytes unknown - they do not appear to change in my
 current set up for any of the controllers.
 
 default set up is identical for 53c810a and 53c875 NVRAM
 (Removable Media added Symbios BIOS version 4.09)
 
 boot configuration
 
 boot order set by order of the devices in this table::
 
     04 00 0f 00 00 10 00 50 00 00 01 00 00 62 -- 1st controller
     04 00 03 00 00 10 00 58 00 00 01 00 00 63    2nd controller
     04 00 01 00 00 10 00 48 00 00 01 00 00 61    3rd controller
     00 00 00 00 00 00 00 00 00 00 00 00 00 00    4th controller
         |  |  |  |     |        |     |  |
         |  |  |  |     |        |      ---- PCI io port adr
         |  |  |  |     |         --0x01 init/scan at boot time
         |  |  |  |      --PCI device/function number (0xdddddfff)
         |  |   ----- ?? PCI vendor ID (lsb/msb)
             ----PCI device ID (lsb/msb)
 
     ?? use of this data is a guess but seems reasonable
 
 remaining bytes unknown - they do not appear to change in my
 current set up
 
 default set up is identical for 53c810a and 53c875 NVRAM
 --------------------------------------------------------
 
 device set up (up to 16 devices - includes controller)::
 
     0f 00 08 08 64 00 0a 00 - id 0
     0f 00 08 08 64 00 0a 00
     0f 00 08 08 64 00 0a 00
     0f 00 08 08 64 00 0a 00
     0f 00 08 08 64 00 0a 00
     0f 00 08 08 64 00 0a 00
     0f 00 08 08 64 00 0a 00
     0f 00 08 08 64 00 0a 00
 
     0f 00 08 08 64 00 0a 00
     0f 00 08 08 64 00 0a 00
     0f 00 08 08 64 00 0a 00
     0f 00 08 08 64 00 0a 00
     0f 00 08 08 64 00 0a 00
     0f 00 08 08 64 00 0a 00
     0f 00 08 08 64 00 0a 00
     0f 00 08 08 64 00 0a 00 - id 15
     |     |  |  |     |  |
     |     |  |  |      ----timeout (lsb/msb)
     |     |  |   --synch period (0x?? 40 Mtrans/sec- fast 40) (probably 0x28)
     |     |  |                  (0x30 20 Mtrans/sec- fast 20)
     |     |  |                  (0x64 10 Mtrans/sec- fast )
     |     |  |                  (0xc8  5 Mtrans/sec)
     |     |  |                  (0x00  asynchronous)
     |     |   -- ?? max sync offset (0x08 in NVRAM on 53c810a)
     |     |                         (0x10 in NVRAM on 53c875)
     |      --device bus width (0x08 narrow)
     |                         (0x10 16 bit wide)
     --flag bits
         0x00000001 - disconnect enabled
         0x00000010 - scan at boot time
         0x00000100 - scan luns
         0x00001000 - queue tags enabled
 
 remaining bytes unknown - they do not appear to change in my
 current set up
 
 ?? use of this data is a guess but seems reasonable
 (but it could be max bus width)
 
 default set up for 53c810a NVRAM
 default set up for 53c875 NVRAM
 
                                 - bus width     - 0x10
                                 - sync offset ? - 0x10
                                 - sync period   - 0x30
 
 ?? spare device space (32 bit bus ??)
 
 ::
 
     00 00 00 00 00 00 00 00  (19x8bytes)
     .
     .
     00 00 00 00 00 00 00 00
 
 default set up is identical for 53c810a and 53c875 NVRAM
 --------------------------------------------------------
 
 trailer::
 
     fe fe   - ? end marker ?
     00 00
     00 00
 
 default set up is identical for 53c810a and 53c875 NVRAM
 -----------------------------------------------------------
 
 
 
 17.3 Tekram NVRAM layout
 ------------------------
 
 nvram 64x16 (1024 bit)
 
 Drive settings::
 
     Drive ID 0-15 (addr 0x0yyyy0 = device setup, yyyy = ID)
                 (addr 0x0yyyy1 = 0x0000)
 
         x x x x  x x x x  x x x x  x x x x
                 | | |      | |  | | | |
                 | | |      | |  | | |  ----- parity check   0 - off
                 | | |      | |  | | |                       1 - on
                 | | |      | |  | | |
                 | | |      | |  | |  ------- sync neg       0 - off
                 | | |      | |  | |                         1 - on
                 | | |      | |  | |
                 | | |      | |  |  --------- disconnect     0 - off
                 | | |      | |  |                           1 - on
                 | | |      | |  |
                 | | |      | |   ----------- start cmd      0 - off
                 | | |      | |                              1 - on
                 | | |      | |
                 | | |      |  -------------- tagged cmds    0 - off
                 | | |      |                                1 - on
                 | | |      |
                 | | |       ---------------- wide neg       0 - off
                 | | |                                       1 - on
                 | | |
                     --------------------------- sync rate      0 - 10.0 Mtrans/sec
                                                             1 -  8.0
                                                             2 -  6.6
                                                             3 -  5.7
                                                             4 -  5.0
                                                             5 -  4.0
                                                             6 -  3.0
                                                             7 -  2.0
                                                             7 -  2.0
                                                             8 - 20.0
                                                             9 - 16.7
                                                             a - 13.9
                                                             b - 11.9
 
 Global settings
 
 Host flags 0 (addr 0x100000, 32)::
 
     x x x x  x x x x  x x x x  x x x x
     | | | |  | | | |           | | | |
     | | | |  | | | |            ----------- host ID    0x00 - 0x0f
     | | | |  | | | |
     | | | |  | | |  ----------------------- support for    0 - off
     | | | |  | | |                          > 2 drives     1 - on
     | | | |  | | |
     | | | |  | |  ------------------------- support drives 0 - off
     | | | |  | |                            > 1Gbytes      1 - on
     | | | |  | |
     | | | |  |  --------------------------- bus reset on   0 - off
     | | | |  |                                power on     1 - on
     | | | |  |
     | | | |   ----------------------------- active neg     0 - off
     | | | |                                                1 - on
     | | | |
     | | |  -------------------------------- imm seek       0 - off
     | | |                                                  1 - on
     | | |
     | |  ---------------------------------- scan luns      0 - off
     | |                                                    1 - on
     | |
      -------------------------------------- removable      0 - disable
                                             as BIOS dev    1 - boot device
                                                            2 - all
 
 Host flags 1 (addr 0x100001, 33)::
 
     x x x x  x x x x  x x x x  x x x x
                | | |             | | |
                | | |              --------- boot delay     0 -   3 sec
                | | |                                       1 -   5
                | | |                                       2 -  10
                | | |                                       3 -  20
                | | |                                       4 -  30
                | | |                                       5 -  60
                | | |                                       6 - 120
                | | |
                 --------------------------- max tag cmds   0 -  2
                                                            1 -  4
                                                            2 -  8
                                                            3 - 16
                                                            4 - 32
 
 Host flags 2 (addr 0x100010, 34)::
 
     x x x x  x x x x  x x x x  x x x x
                                      |
                                       ----- F2/F6 enable   0 - off ???
                                                            1 - on  ???
 
 checksum (addr 0x111111)
 
 checksum = 0x1234 - (sum addr 0-63)
 
 ----------------------------------------------------------------------------
 
 default nvram data::
 
     0x0037 0x0000 0x0037 0x0000 0x0037 0x0000 0x0037 0x0000
     0x0037 0x0000 0x0037 0x0000 0x0037 0x0000 0x0037 0x0000
     0x0037 0x0000 0x0037 0x0000 0x0037 0x0000 0x0037 0x0000
     0x0037 0x0000 0x0037 0x0000 0x0037 0x0000 0x0037 0x0000
 
     0x0f07 0x0400 0x0001 0x0000 0x0000 0x0000 0x0000 0x0000
     0x0000 0x0000 0x0000 0x0000 0x0000 0x0000 0x0000 0x0000
     0x0000 0x0000 0x0000 0x0000 0x0000 0x0000 0x0000 0x0000
     0x0000 0x0000 0x0000 0x0000 0x0000 0x0000 0x0000 0xfbbc
 
 
 18. Support for Big Endian
 ==========================
 
 The PCI local bus has been primarily designed for x86 architecture.
 As a consequence, PCI devices generally expect DWORDS using little endian
 byte ordering.
 
 18.1 Big Endian CPU
 -------------------
 
 In order to support NCR chips on a Big Endian architecture the driver has to
 perform byte reordering each time it is needed. This feature has been
 added to the driver by Cort <cort@cs.nmt.edu> and is available in driver
 version 2.5 and later ones. For the moment Big Endian support has only
 been tested on Linux/PPC (PowerPC).
 
 18.2 NCR chip in Big Endian mode of operations
 ----------------------------------------------
 
 It can be read in SYMBIOS documentation that some chips support a special
 Big Endian mode, on paper: 53C815, 53C825A, 53C875, 53C875N, 53C895.
 This mode of operations is not software-selectable, but needs pin named
 BigLit to be pulled-up. Using this mode, most of byte reorderings should
 be avoided when the driver is running on a Big Endian CPU.
 Driver version 2.5 is also, in theory, ready for this feature.

This page was automatically generated by the 2.1.0 LXR engine. The LXR team