linux/Documentation/scsi/ncr53c8xx.txt
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   1The Linux NCR53C8XX/SYM53C8XX drivers README file
   2
   3Written by Gerard Roudier <groudier@free.fr>
   421 Rue Carnot
   595170 DEUIL LA BARRE - FRANCE
   6
   729 May 1999
   8===============================================================================
   9
  101.  Introduction
  112.  Supported chips and SCSI features
  123.  Advantages of the enhanced 896 driver
  13      3.1 Optimized SCSI SCRIPTS
  14      3.2 New features of the SYM53C896 (64 bit PCI dual LVD SCSI controller)
  154.  Memory mapped I/O versus normal I/O
  165.  Tagged command queueing
  176.  Parity checking
  187.  Profiling information
  198.  Control commands
  20      8.1  Set minimum synchronous period
  21      8.2  Set wide size
  22      8.3  Set maximum number of concurrent tagged commands
  23      8.4  Set order type for tagged command
  24      8.5  Set debug mode
  25      8.6  Clear profile counters
  26      8.7  Set flag (no_disc)
  27      8.8  Set verbose level
  28      8.9  Reset all logical units of a target
  29      8.10 Abort all tasks of all logical units of a target
  309.  Configuration parameters
  3110. Boot setup commands
  32      10.1 Syntax
  33      10.2 Available arguments
  34             10.2.1  Master parity checking
  35             10.2.2  Scsi parity checking
  36             10.2.3  Scsi disconnections
  37             10.2.4  Special features
  38             10.2.5  Ultra SCSI support
  39             10.2.6  Default number of tagged commands
  40             10.2.7  Default synchronous period factor
  41             10.2.8  Negotiate synchronous with all devices
  42             10.2.9  Verbosity level
  43             10.2.10 Debug mode
  44             10.2.11 Burst max
  45             10.2.12 LED support
  46             10.2.13 Max wide
  47             10.2.14 Differential mode
  48             10.2.15 IRQ mode
  49             10.2.16 Reverse probe
  50             10.2.17 Fix up PCI configuration space
  51             10.2.18 Serial NVRAM
  52             10.2.19 Check SCSI BUS 
  53             10.2.20 Exclude a host from being attached
  54             10.2.21 Suggest a default SCSI id for hosts
  55             10.2.22 Enable use of IMMEDIATE ARBITRATION
  56      10.3 Advised boot setup commands
  57      10.4 PCI configuration fix-up boot option
  58      10.5 Serial NVRAM support boot option
  59      10.6 SCSI BUS checking boot option
  60      10.7 IMMEDIATE ARBITRATION boot option
  6111. Some constants and flags of the ncr53c8xx.h header file
  6212. Installation
  6313. Architecture dependent features
  6414. Known problems
  65      14.1 Tagged commands with Iomega Jaz device
  66      14.2 Device names change when another controller is added
  67      14.3 Using only 8 bit devices with a WIDE SCSI controller.
  68      14.4 Possible data corruption during a Memory Write and Invalidate
  69      14.5 IRQ sharing problems
  7015. SCSI problem troubleshooting
  71      15.1 Problem tracking
  72      15.2 Understanding hardware error reports
  7316. Synchronous transfer negotiation tables
  74      16.1 Synchronous timings for 53C875 and 53C860 Ultra-SCSI controllers
  75      16.2 Synchronous timings for fast SCSI-2 53C8XX controllers
  7617. Serial NVRAM support (by Richard Waltham)
  77      17.1 Features
  78      17.2 Symbios NVRAM layout
  79      17.3 Tekram  NVRAM layout
  8018. Support for Big Endian
  81      18.1 Big Endian CPU
  82      18.2 NCR chip in Big Endian mode of operations
  83
  84===============================================================================
  85
  861. Introduction
  87
  88The initial Linux ncr53c8xx driver has been a port of the ncr driver from 
  89FreeBSD that has been achieved in November 1995 by:
  90          Gerard Roudier              <groudier@free.fr>
  91
  92The original driver has been written for 386bsd and FreeBSD by:
  93          Wolfgang Stanglmeier        <wolf@cologne.de>
  94          Stefan Esser                <se@mi.Uni-Koeln.de>
  95
  96It is now available as a bundle of 2 drivers:
  97
  98- ncr53c8xx generic driver that supports all the SYM53C8XX family including 
  99  the earliest 810 rev. 1, the latest 896 (2 channel LVD SCSI controller) and
 100  the new 895A (1 channel LVD SCSI controller).
 101- sym53c8xx enhanced driver (a.k.a. 896 drivers) that drops support of oldest 
 102  chips in order to gain advantage of new features, as LOAD/STORE instructions 
 103  available since the 810A and hardware phase mismatch available with the 
 104  896 and the 895A.
 105
 106You can find technical information about the NCR 8xx family in the
 107PCI-HOWTO written by Michael Will and in the SCSI-HOWTO written by
 108Drew Eckhardt.
 109
 110Information about new chips is available at LSILOGIC web server:
 111
 112          http://www.lsilogic.com/
 113
 114SCSI standard documentations are available at SYMBIOS ftp server:
 115
 116          ftp://ftp.symbios.com/
 117
 118Useful SCSI tools written by Eric Youngdale are available at tsx-11:
 119
 120          ftp://tsx-11.mit.edu/pub/linux/ALPHA/scsi/scsiinfo-X.Y.tar.gz
 121          ftp://tsx-11.mit.edu/pub/linux/ALPHA/scsi/scsidev-X.Y.tar.gz
 122
 123These tools are not ALPHA but quite clean and work quite well.
 124It is essential you have the 'scsiinfo' package.
 125
 126This short documentation describes the features of the generic and enhanced
 127drivers, configuration parameters and control commands available through 
 128the proc SCSI file system read / write operations.
 129
 130This driver has been tested OK with linux/i386, Linux/Alpha and Linux/PPC.
 131
 132Latest driver version and patches are available at:
 133
 134          ftp://ftp.tux.org/pub/people/gerard-roudier
 135or
 136          ftp://ftp.symbios.com/mirror/ftp.tux.org/pub/tux/roudier/drivers
 137
 138I am not a native speaker of English and there are probably lots of
 139mistakes in this README file. Any help will be welcome.
 140
 141
 1422. Supported chips and SCSI features
 143
 144The following features are supported for all chips:
 145
 146        Synchronous negotiation
 147        Disconnection
 148        Tagged command queuing
 149        SCSI parity checking
 150        Master parity checking
 151
 152"Wide negotiation" is supported for chips that allow it.  The
 153following table shows some characteristics of NCR 8xx family chips 
 154and what drivers support them.
 155
 156                                                  Supported by   Supported by
 157       On board                                   the generic    the enhanced 
 158Chip   SDMS BIOS   Wide   SCSI std.   Max. sync   driver         driver
 159----   ---------   ----   ---------   ----------  ------------   -------------
 160810        N         N      FAST10    10 MB/s        Y             N
 161810A       N         N      FAST10    10 MB/s        Y             Y
 162815        Y         N      FAST10    10 MB/s        Y             N
 163825        Y         Y      FAST10    20 MB/s        Y             N
 164825A       Y         Y      FAST10    20 MB/s        Y             Y
 165860        N         N      FAST20    20 MB/s        Y             Y
 166875        Y         Y      FAST20    40 MB/s        Y             Y
 167876        Y         Y      FAST20    40 MB/s        Y             Y
 168895        Y         Y      FAST40    80 MB/s        Y             Y
 169895A       Y         Y      FAST40    80 MB/s        Y             Y
 170896        Y         Y      FAST40    80 MB/s        Y             Y
 171897        Y         Y      FAST40    80 MB/s        Y             Y
 1721510D      Y         Y      FAST40    80 MB/s        Y             Y
 1731010       Y         Y      FAST80   160 MB/s        N             Y
 1741010_66*   Y         Y      FAST80   160 MB/s        N             Y
 175
 176* Chip supports 33MHz and 66MHz PCI buses.
 177
 178
 179Summary of other supported features:
 180
 181Module:                allow to load the driver
 182Memory mapped I/O:     increases performance
 183Profiling information: read operations from the proc SCSI file system
 184Control commands:      write operations to the proc SCSI file system
 185Debugging information: written to syslog (expert only)
 186Scatter / gather
 187Shared interrupt
 188Boot setup commands
 189Serial NVRAM:          Symbios and Tekram formats
 190
 191
 1923. Advantages of the enhanced 896 driver
 193
 1943.1 Optimized SCSI SCRIPTS.
 195
 196The 810A, 825A, 875, 895, 896 and 895A support new SCSI SCRIPTS instructions 
 197named LOAD and STORE that allow to move up to 1 DWORD from/to an IO register 
 198to/from memory much faster that the MOVE MEMORY instruction that is supported 
 199by the 53c7xx and 53c8xx family.
 200The LOAD/STORE instructions support absolute and DSA relative addressing 
 201modes.  The SCSI SCRIPTS had been entirely rewritten using LOAD/STORE instead 
 202of MOVE MEMORY instructions.
 203
 2043.2 New features of the SYM53C896 (64 bit PCI dual LVD SCSI controller)
 205
 206The 896 and the 895A allows handling of the phase mismatch context from 
 207SCRIPTS (avoids the phase mismatch interrupt that stops the SCSI processor 
 208until the C code has saved the context of the transfer).
 209Implementing this without using LOAD/STORE instructions would be painful 
 210and I didn't even want to try it.
 211
 212The 896 chip supports 64 bit PCI transactions and addressing, while the 
 213895A supports 32 bit PCI transactions and 64 bit addressing.
 214The SCRIPTS processor of these chips is not true 64 bit, but uses segment 
 215registers for bit 32-63. Another interesting feature is that LOAD/STORE 
 216instructions that address the on-chip RAM (8k) remain internal to the chip.
 217
 218Due to the use of LOAD/STORE SCRIPTS instructions, this driver does not 
 219support the following chips:
 220- SYM53C810 revision < 0x10 (16)
 221- SYM53C815 all revisions
 222- SYM53C825 revision < 0x10 (16)
 223
 2244. Memory mapped I/O versus normal I/O
 225
 226Memory mapped I/O has less latency than normal I/O.  Since
 227linux-1.3.x, memory mapped I/O is used rather than normal I/O.  Memory
 228mapped I/O seems to work fine on most hardware configurations, but
 229some poorly designed motherboards may break this feature.
 230
 231The configuration option CONFIG_SCSI_NCR53C8XX_IOMAPPED forces the
 232driver to use normal I/O in all cases.
 233
 234
 2355. Tagged command queueing
 236
 237Queuing more than 1 command at a time to a device allows it to perform 
 238optimizations based on actual head positions and its mechanical 
 239characteristics. This feature may also reduce average command latency.
 240In order to really gain advantage of this feature, devices must have 
 241a reasonable cache size (No miracle is to be expected for a low-end 
 242hard disk with 128 KB or less).
 243Some known SCSI devices do not properly support tagged command queuing.
 244Generally, firmware revisions that fix this kind of problems are available 
 245at respective vendor web/ftp sites.
 246All I can say is that the hard disks I use on my machines behave well with 
 247this driver with tagged command queuing enabled:
 248
 249- IBM S12 0662
 250- Conner 1080S
 251- Quantum Atlas I
 252- Quantum Atlas II
 253
 254If your controller has NVRAM, you can configure this feature per target 
 255from the user setup tool. The Tekram Setup program allows to tune the 
 256maximum number of queued commands up to 32. The Symbios Setup only allows 
 257to enable or disable this feature.
 258
 259The maximum number of simultaneous tagged commands queued to a device
 260is currently set to 8 by default.  This value is suitable for most SCSI
 261disks.  With large SCSI disks (>= 2GB, cache >= 512KB, average seek time
 262<= 10 ms), using a larger value may give better performances.
 263
 264The sym53c8xx driver supports up to 255 commands per device, and the 
 265generic ncr53c8xx driver supports up to 64, but using more than 32 is 
 266generally not worth-while, unless you are using a very large disk or disk 
 267array. It is noticeable that most of recent hard disks seem not to accept 
 268more than 64 simultaneous commands. So, using more than 64 queued commands 
 269is probably just resource wasting.
 270
 271If your controller does not have NVRAM or if it is managed by the SDMS 
 272BIOS/SETUP, you can configure tagged queueing feature and device queue 
 273depths from the boot command-line. For example:
 274
 275  ncr53c8xx=tags:4/t2t3q15-t4q7/t1u0q32
 276
 277will set tagged commands queue depths as follow:
 278
 279- target 2  all luns  on controller 0 --> 15
 280- target 3  all luns  on controller 0 --> 15
 281- target 4  all luns  on controller 0 -->  7
 282- target 1  lun 0     on controller 1 --> 32
 283- all other target/lun                -->  4
 284
 285In some special conditions, some SCSI disk firmwares may return a
 286QUEUE FULL status for a SCSI command. This behaviour is managed by the
 287driver using the following heuristic:
 288
 289- Each time a QUEUE FULL status is returned, tagged queue depth is reduced 
 290  to the actual number of disconnected commands. 
 291
 292- Every 1000 successfully completed SCSI commands, if allowed by the
 293  current limit, the maximum number of queueable commands is incremented.
 294
 295Since QUEUE FULL status reception and handling is resource wasting, the 
 296driver notifies by default this problem to user by indicating the actual 
 297number of commands used and their status, as well as its decision on the 
 298device queue depth change.
 299The heuristic used by the driver in handling QUEUE FULL ensures that the 
 300impact on performances is not too bad. You can get rid of the messages by 
 301setting verbose level to zero, as follow:
 302
 3031st method: boot your system using 'ncr53c8xx=verb:0' option.
 3042nd method: apply "setverbose 0" control command to the proc fs entry 
 305            corresponding to your controller after boot-up.
 306
 3076. Parity checking
 308
 309The driver supports SCSI parity checking and PCI bus master parity
 310checking.  These features must be enabled in order to ensure safe data
 311transfers.  However, some flawed devices or mother boards will have
 312problems with parity. You can disable either PCI parity or SCSI parity 
 313checking by entering appropriate options from the boot command line.
 314(See 10: Boot setup commands).
 315
 3167. Profiling information
 317
 318Profiling information is available through the proc SCSI file system.
 319Since gathering profiling information may impact performances, this 
 320feature is disabled by default and requires a compilation configuration 
 321option to be set to Y.
 322
 323The device associated with a host has the following pathname:
 324
 325          /proc/scsi/ncr53c8xx/N     (N=0,1,2 ....)
 326
 327Generally, only 1 board is used on hardware configuration, and that device is:
 328          /proc/scsi/ncr53c8xx/0
 329
 330However, if the driver has been made as module, the number of the
 331hosts is incremented each time the driver is loaded.
 332
 333In order to display profiling information, just enter:
 334
 335         cat /proc/scsi/ncr53c8xx/0
 336
 337and you will get something like the following text:
 338
 339-------------------------------------------------------
 340General information:
 341  Chip NCR53C810, device id 0x1, revision id 0x2
 342  IO port address 0x6000, IRQ number 10
 343  Using memory mapped IO at virtual address 0x282c000
 344  Synchronous transfer period 25, max commands per lun 4
 345Profiling information:
 346  num_trans    = 18014
 347  num_kbytes   = 671314
 348  num_disc     = 25763
 349  num_break    = 1673
 350  num_int      = 1685
 351  num_fly      = 18038
 352  ms_setup     = 4940
 353  ms_data      = 369940
 354  ms_disc      = 183090
 355  ms_post      = 1320
 356-------------------------------------------------------
 357
 358General information is easy to understand. The device ID and the
 359revision ID identify the SCSI chip as follows:
 360
 361Chip    Device id     Revision Id
 362----    ---------     -----------
 363810       0x1            <  0x10
 364810A      0x1            >= 0x10
 365815       0x4
 366825       0x3            <  0x10
 367860       0x6
 368825A      0x3            >= 0x10
 369875       0xf
 370895       0xc
 371
 372The profiling information is updated upon completion of SCSI commands.
 373A data structure is allocated and zeroed when the host adapter is
 374attached. So, if the driver is a module, the profile counters are
 375cleared each time the driver is loaded.  The "clearprof" command
 376allows you to clear these counters at any time.
 377
 378The following counters are available:
 379
 380("num" prefix means "number of",
 381"ms" means milli-seconds)
 382
 383num_trans
 384        Number of completed commands
 385        Example above: 18014 completed commands
 386
 387num_kbytes
 388        Number of kbytes transferred
 389        Example above: 671 MB transferred
 390
 391num_disc
 392        Number of SCSI disconnections
 393        Example above: 25763 SCSI disconnections
 394
 395num_break
 396        number of script interruptions (phase mismatch)
 397        Example above: 1673 script interruptions
 398
 399num_int
 400        Number of interrupts other than "on the fly"
 401        Example above: 1685 interruptions not "on the fly"
 402
 403num_fly
 404        Number of interrupts "on the fly"
 405        Example above: 18038 interruptions "on the fly"
 406
 407ms_setup
 408        Elapsed time for SCSI commands setups
 409        Example above: 4.94 seconds
 410
 411ms_data
 412        Elapsed time for data transfers
 413        Example above: 369.94 seconds spent for data transfer
 414
 415ms_disc
 416        Elapsed time for SCSI disconnections
 417        Example above: 183.09 seconds spent disconnected
 418
 419ms_post
 420        Elapsed time for command post processing
 421        (time from SCSI status get to command completion call)
 422        Example above: 1.32 seconds spent for post processing
 423
 424Due to the 1/100 second tick of the system clock, "ms_post" time may
 425be wrong.
 426
 427In the example above, we got 18038 interrupts "on the fly" and only
 4281673 script breaks generally due to disconnections inside a segment 
 429of the scatter list.
 430
 431
 4328. Control commands
 433
 434Control commands can be sent to the driver with write operations to
 435the proc SCSI file system. The generic command syntax is the
 436following:
 437
 438      echo "<verb> <parameters>" >/proc/scsi/ncr53c8xx/0
 439      (assumes controller number is 0)
 440
 441Using "all" for "<target>" parameter with the commands below will
 442apply to all targets of the SCSI chain (except the controller).
 443
 444Available commands:
 445
 4468.1 Set minimum synchronous period factor
 447
 448    setsync <target> <period factor>
 449
 450    target:    target number
 451    period:    minimum synchronous period.
 452               Maximum speed = 1000/(4*period factor) except for special
 453               cases below.
 454
 455    Specify a period of 255, to force asynchronous transfer mode.
 456
 457      10 means 25 nano-seconds synchronous period
 458      11 means 30 nano-seconds synchronous period
 459      12 means 50 nano-seconds synchronous period
 460
 4618.2 Set wide size
 462
 463    setwide <target> <size>
 464
 465    target:    target number
 466    size:      0=8 bits, 1=16bits
 467
 4688.3 Set maximum number of concurrent tagged commands
 469 
 470    settags <target> <tags>
 471
 472    target:    target number
 473    tags:      number of concurrent tagged commands
 474               must not be greater than SCSI_NCR_MAX_TAGS (default: 8)
 475
 4768.4 Set order type for tagged command
 477
 478    setorder <order>
 479
 480    order:     3 possible values:
 481               simple: use SIMPLE TAG for all operations (read and write)
 482               ordered: use ORDERED TAG for all operations
 483               default: use default tag type,
 484                        SIMPLE  TAG for read  operations
 485                        ORDERED TAG for write operations
 486
 487
 4888.5 Set debug mode
 489
 490    setdebug <list of debug flags>
 491
 492    Available debug flags:
 493        alloc:   print info about memory allocations (ccb, lcb)
 494        queue:   print info about insertions into the command start queue
 495        result:  print sense data on CHECK CONDITION status
 496        scatter: print info about the scatter process
 497        scripts: print info about the script binding process
 498        tiny:    print minimal debugging information
 499        timing:  print timing information of the NCR chip
 500        nego:    print information about SCSI negotiations
 501        phase:   print information on script interruptions
 502
 503    Use "setdebug" with no argument to reset debug flags.
 504
 505
 5068.6 Clear profile counters
 507
 508    clearprof
 509
 510    The profile counters are automatically cleared when the amount of
 511    data transferred reaches 1000 GB in order to avoid overflow.
 512    The "clearprof" command allows you to clear these counters at any time.
 513
 514
 5158.7 Set flag (no_disc)
 516 
 517    setflag <target> <flag>
 518
 519    target:    target number
 520
 521    For the moment, only one flag is available:
 522
 523        no_disc:   not allow target to disconnect.
 524
 525    Do not specify any flag in order to reset the flag. For example:
 526    - setflag 4
 527      will reset no_disc flag for target 4, so will allow it disconnections.
 528    - setflag all
 529      will allow disconnection for all devices on the SCSI bus.
 530
 531
 5328.8 Set verbose level
 533
 534    setverbose #level
 535
 536    The driver default verbose level is 1. This command allows to change 
 537    th driver verbose level after boot-up.
 538
 5398.9 Reset all logical units of a target
 540
 541    resetdev <target>
 542
 543    target:    target number
 544    The driver will try to send a BUS DEVICE RESET message to the target.
 545    (Only supported by the SYM53C8XX driver and provided for test purpose)
 546
 5478.10 Abort all tasks of all logical units of a target
 548
 549    cleardev <target>
 550
 551    target:    target number
 552    The driver will try to send a ABORT message to all the logical units 
 553    of the target.
 554    (Only supported by the SYM53C8XX driver and provided for test purpose)
 555
 556
 5579. Configuration parameters
 558
 559If the firmware of all your devices is perfect enough, all the
 560features supported by the driver can be enabled at start-up.  However,
 561if only one has a flaw for some SCSI feature, you can disable the
 562support by the driver of this feature at linux start-up and enable
 563this feature after boot-up only for devices that support it safely.
 564
 565CONFIG_SCSI_NCR53C8XX_IOMAPPED       (default answer: n)
 566    Answer "y" if you suspect your mother board to not allow memory mapped I/O.
 567    May slow down performance a little.  This option is required by
 568    Linux/PPC and is used no matter what you select here.  Linux/PPC
 569    suffers no performance loss with this option since all IO is memory
 570    mapped anyway.
 571
 572CONFIG_SCSI_NCR53C8XX_DEFAULT_TAGS    (default answer: 8)
 573    Default tagged command queue depth.
 574
 575CONFIG_SCSI_NCR53C8XX_MAX_TAGS         (default answer: 8)
 576    This option allows you to specify the maximum number of tagged commands 
 577    that can be queued to a device. The maximum supported value is 32.
 578
 579CONFIG_SCSI_NCR53C8XX_SYNC            (default answer: 5)
 580    This option allows you to specify the frequency in MHz the driver 
 581    will use at boot time for synchronous data transfer negotiations.
 582    This frequency can be changed later with the "setsync" control command.
 583    0 means "asynchronous data transfers".
 584
 585CONFIG_SCSI_NCR53C8XX_FORCE_SYNC_NEGO (default answer: n)
 586    Force synchronous negotiation for all SCSI-2 devices.
 587    Some SCSI-2 devices do not report this feature in byte 7 of inquiry 
 588    response but do support it properly (TAMARACK scanners for example).
 589
 590CONFIG_SCSI_NCR53C8XX_NO_DISCONNECT   (default and only reasonable answer: n)
 591    If you suspect a device of yours does not properly support disconnections,
 592    you can answer "y". Then, all SCSI devices will never disconnect the bus 
 593    even while performing long SCSI operations.
 594
 595CONFIG_SCSI_NCR53C8XX_SYMBIOS_COMPAT
 596    Genuine SYMBIOS boards use GPIO0 in output for controller LED and GPIO3 
 597    bit as a flag indicating singled-ended/differential interface.
 598    If all the boards of your system are genuine SYMBIOS boards or use
 599    BIOS and drivers from SYMBIOS, you would want to enable this option.
 600    This option must NOT be enabled if your system has at least one 53C8XX 
 601    based scsi board with a vendor-specific BIOS.
 602    For example, Tekram DC-390/U, DC-390/W and DC-390/F scsi controllers 
 603    use a vendor-specific BIOS and are known to not use SYMBIOS compatible 
 604    GPIO wiring. So, this option must not be enabled if your system has 
 605    such a board installed.
 606
 607CONFIG_SCSI_NCR53C8XX_NVRAM_DETECT
 608    Enable support for reading the serial NVRAM data on Symbios and
 609    some Symbios compatible cards, and Tekram DC390W/U/F cards. Useful for
 610    systems with more than one Symbios compatible controller where at least
 611    one has a serial NVRAM, or for a system with a mixture of Symbios and
 612    Tekram cards. Enables setting the boot order of host adaptors
 613    to something other than the default order or "reverse probe" order. 
 614    Also enables Symbios and Tekram cards to be distinguished so
 615    CONFIG_SCSI_NCR53C8XX_SYMBIOS_COMPAT may be set in a system with a
 616    mixture of Symbios and Tekram cards so the Symbios cards can make use of
 617    the full range of Symbios features, differential, led pin, without
 618    causing problems for the Tekram card(s).
 619
 62010. Boot setup commands
 621
 62210.1 Syntax
 623
 624Setup commands can be passed to the driver either at boot time or as a 
 625string variable using 'insmod'.
 626
 627A boot setup command for the ncr53c8xx (sym53c8xx) driver begins with the 
 628driver name "ncr53c8xx="(sym53c8xx). The kernel syntax parser then expects 
 629an optional list of integers separated with comma followed by an optional 
 630list of comma-separated strings. Example of boot setup command under lilo 
 631prompt:
 632
 633lilo: linux root=/dev/hda2 ncr53c8xx=tags:4,sync:10,debug:0x200
 634
 635- enable tagged commands, up to 4 tagged commands queued.
 636- set synchronous negotiation speed to 10 Mega-transfers / second.
 637- set DEBUG_NEGO flag.
 638
 639Since comma seems not to be allowed when defining a string variable using  
 640'insmod', the driver also accepts <space> as option separator. 
 641The following command will install driver module with the same options as 
 642above.
 643
 644    insmod ncr53c8xx.o ncr53c8xx="tags:4 sync:10 debug:0x200"
 645
 646For the moment, the integer list of arguments is discarded by the driver. 
 647It will be used in the future in order to allow a per controller setup.
 648
 649Each string argument must be specified as "keyword:value". Only lower-case 
 650characters and digits are allowed.
 651
 652In a system that contains multiple 53C8xx adapters insmod will install the 
 653specified driver on each adapter. To exclude a chip use the 'excl' keyword.
 654
 655The sequence of commands, 
 656
 657    insmod sym53c8xx sym53c8xx=excl:0x1400
 658    insmod ncr53c8xx
 659
 660installs the sym53c8xx driver on all adapters except the one at IO port 
 661address 0x1400 and then installs the ncr53c8xx driver to the adapter at IO 
 662port address 0x1400.
 663
 664
 66510.2 Available arguments
 666
 66710.2.1  Master parity checking
 668        mpar:y     enabled
 669        mpar:n     disabled
 670
 67110.2.2  Scsi parity checking
 672        spar:y     enabled
 673        spar:n     disabled
 674
 67510.2.3  Scsi disconnections
 676        disc:y     enabled
 677        disc:n     disabled
 678 
 67910.2.4  Special features
 680   Only apply to 810A, 825A, 860, 875 and 895 controllers.
 681   Have no effect with other ones.
 682        specf:y    (or 1) enabled
 683        specf:n    (or 0) disabled
 684        specf:3           enabled except Memory Write And Invalidate
 685   The default driver setup is 'specf:3'. As a consequence, option 'specf:y' 
 686   must be specified in the boot setup command to enable Memory Write And 
 687   Invalidate.
 688
 68910.2.5  Ultra SCSI support
 690   Only apply to 860, 875, 895, 895a, 896, 1010 and 1010_66 controllers.
 691   Have no effect with other ones.
 692        ultra:n    All ultra speeds enabled
 693        ultra:2    Ultra2 enabled
 694        ultra:1    Ultra enabled
 695        ultra:0    Ultra speeds disabled
 696
 69710.2.6  Default number of tagged commands
 698        tags:0     (or tags:1 ) tagged command queuing disabled
 699        tags:#tags (#tags  > 1) tagged command queuing enabled
 700  #tags will be truncated to the max queued commands configuration parameter.
 701  This option also allows to specify a command queue depth for each device 
 702  that support tagged command queueing.
 703  Example:
 704      ncr53c8xx=tags:10/t2t3q16-t5q24/t1u2q32
 705               will set devices queue depth as follow:
 706      - controller #0 target #2 and target #3                  -> 16 commands,
 707      - controller #0 target #5                                -> 24 commands,
 708      - controller #1 target #1 logical unit #2                -> 32 commands,
 709      - all other logical units (all targets, all controllers) -> 10 commands.
 710
 71110.2.7  Default synchronous period factor
 712        sync:255     disabled (asynchronous transfer mode)
 713        sync:#factor
 714  #factor = 10     Ultra-2 SCSI 40 Mega-transfers / second
 715  #factor = 11     Ultra-2 SCSI 33 Mega-transfers / second
 716  #factor < 25     Ultra   SCSI 20 Mega-transfers / second
 717  #factor < 50     Fast    SCSI-2
 718
 719  In all cases, the driver will use the minimum transfer period supported by 
 720  controllers according to NCR53C8XX chip type.
 721
 72210.2.8  Negotiate synchronous with all devices
 723        (force sync nego)
 724        fsn:y      enabled
 725        fsn:n      disabled
 726
 72710.2.9  Verbosity level
 728        verb:0     minimal
 729        verb:1     normal
 730        verb:2     too much
 731
 73210.2.10 Debug mode
 733        debug:0  clear debug flags
 734        debug:#x   set debug flags
 735  #x is an integer value combining the following power-of-2 values:
 736  DEBUG_ALLOC       0x1
 737  DEBUG_PHASE       0x2
 738  DEBUG_POLL        0x4
 739  DEBUG_QUEUE       0x8
 740  DEBUG_RESULT     0x10
 741  DEBUG_SCATTER    0x20
 742  DEBUG_SCRIPT     0x40
 743  DEBUG_TINY       0x80
 744  DEBUG_TIMING    0x100
 745  DEBUG_NEGO      0x200
 746  DEBUG_TAGS      0x400
 747  DEBUG_FREEZE    0x800
 748  DEBUG_RESTART  0x1000
 749
 750  You can play safely with DEBUG_NEGO. However, some of these flags may 
 751  generate bunches of syslog messages. 
 752
 75310.2.11 Burst max
 754        burst:0    burst disabled
 755        burst:255  get burst length from initial IO register settings.
 756        burst:#x   burst enabled (1<<#x burst transfers max)
 757  #x is an integer value which is log base 2 of the burst transfers max.
 758  The NCR53C875 and NCR53C825A support up to 128 burst transfers (#x = 7).
 759  Other chips only support up to 16 (#x = 4).
 760  This is a maximum value. The driver set the burst length according to chip 
 761  and revision ids. By default the driver uses the maximum value supported 
 762  by the chip.
 763
 76410.2.12 LED support
 765        led:1      enable  LED support
 766        led:0      disable LED support
 767  Donnot enable LED support if your scsi board does not use SDMS BIOS.
 768  (See 'Configuration parameters')
 769
 77010.2.13 Max wide
 771        wide:1      wide scsi enabled
 772        wide:0      wide scsi disabled
 773  Some scsi boards use a 875 (ultra wide) and only supply narrow connectors.
 774  If you have connected a wide device with a 50 pins to 68 pins cable 
 775  converter, any accepted wide negotiation will break further data transfers.
 776  In such a case, using "wide:0" in the bootup command will be helpful. 
 777
 77810.2.14 Differential mode
 779        diff:0  never set up diff mode
 780        diff:1  set up diff mode if BIOS set it
 781        diff:2  always set up diff mode
 782        diff:3  set diff mode if GPIO3 is not set
 783
 78410.2.15 IRQ mode
 785        irqm:0     always open drain
 786        irqm:1     same as initial settings (assumed BIOS settings)
 787        irqm:2     always totem pole
 788        irqm:0x10  driver will not use IRQF_SHARED flag when requesting irq
 789        irqm:0x20  driver will not use IRQF_DISABLED flag when requesting irq
 790
 791    (Bits 0x10 and 0x20 can be combined with hardware irq mode option)
 792
 79310.2.16 Reverse probe
 794        revprob:n   probe chip ids from the PCI configuration in this order:
 795                    810, 815, 820, 860, 875, 885, 895, 896
 796        revprob:y   probe chip ids in the reverse order.
 797
 79810.2.17 Fix up PCI configuration space
 799        pcifix:<option bits>
 800
 801    Available option bits:
 802        0x0:   No attempt to fix PCI configuration space registers values.
 803        0x1:   Set PCI cache-line size register if not set.
 804        0x2:   Set write and invalidate bit in PCI command register.
 805        0x4:   Increase if necessary PCI latency timer according to burst max.
 806
 807    Use 'pcifix:7' in order to allow the driver to fix up all PCI features.
 808
 80910.2.18 Serial NVRAM
 810        nvram:n     do not look for serial NVRAM
 811        nvram:y     test controllers for onboard serial NVRAM
 812        (alternate binary form)
 813        mvram=<bits options>
 814        0x01   look for NVRAM  (equivalent to nvram=y)
 815        0x02   ignore NVRAM "Synchronous negotiation" parameters for all devices
 816        0x04   ignore NVRAM "Wide negotiation"  parameter for all devices
 817        0x08   ignore NVRAM "Scan at boot time" parameter for all devices
 818        0x80   also attach controllers set to OFF in the NVRAM (sym53c8xx only)
 819
 82010.2.19 Check SCSI BUS 
 821        buschk:<option bits>
 822
 823    Available option bits:
 824        0x0:   No check.
 825        0x1:   Check and do not attach the controller on error.  
 826        0x2:   Check and just warn on error.
 827        0x4:   Disable SCSI bus integrity checking.
 828
 82910.2.20 Exclude a host from being attached
 830        excl=<io_address>
 831
 832    Prevent host at a given io address from being attached.
 833    For example 'ncr53c8xx=excl:0xb400,excl:0xc000' indicate to the 
 834    ncr53c8xx driver not to attach hosts at address 0xb400 and 0xc000.
 835
 83610.2.21 Suggest a default SCSI id for hosts
 837        hostid:255      no id suggested.
 838        hostid:#x   (0 < x < 7) x suggested for hosts SCSI id.
 839
 840    If a host SCSI id is available from the NVRAM, the driver will ignore 
 841    any value suggested as boot option. Otherwise, if a suggested value 
 842    different from 255 has been supplied, it will use it. Otherwise, it will 
 843    try to deduce the value previously set in the hardware and use value 
 844    7 if the hardware value is zero.
 845
 84610.2.22 Enable use of IMMEDIATE ARBITRATION
 847        (only supported by the sym53c8xx driver. See 10.7 for more details)
 848        iarb:0    do not use this feature.
 849        iarb:#x   use this feature according to bit fields as follow:
 850
 851    bit 0 (1) : enable IARB each time the initiator has been reselected 
 852                when it arbitrated for the SCSI BUS.
 853    (#x >> 4) : maximum number of successive settings of IARB if the initiator 
 854                win arbitration and it has other commands to send to a device.
 855
 856Boot fail safe
 857    safe:y      load the following assumed fail safe initial setup
 858
 859  master parity                 disabled                mpar:n
 860  scsi parity                   enabled                 spar:y
 861  disconnections                not allowed             disc:n
 862  special features              disabled                specf:n
 863  ultra scsi                    disabled                ultra:n
 864  force sync negotiation        disabled                fsn:n
 865  reverse probe                 disabled                revprob:n
 866  PCI fix up                    disabled                pcifix:0
 867  serial NVRAM                  enabled                 nvram:y
 868  verbosity level               2                       verb:2
 869  tagged command queuing        disabled                tags:0
 870  synchronous negotiation       disabled                sync:255
 871  debug flags                   none                    debug:0
 872  burst length                  from BIOS settings      burst:255
 873  LED support                   disabled                led:0
 874  wide support                  disabled                wide:0
 875  settle time                   10 seconds              settle:10
 876  differential support          from BIOS settings      diff:1
 877  irq mode                      from BIOS settings      irqm:1
 878  SCSI BUS check                do not attach on error  buschk:1
 879  immediate arbitration         disabled                iarb:0
 880
 88110.3 Advised boot setup commands
 882
 883If the driver has been configured with default options, the equivalent 
 884boot setup is:
 885
 886   ncr53c8xx=mpar:y,spar:y,disc:y,specf:3,fsn:n,ultra:2,fsn:n,revprob:n,verb:1\
 887             tags:0,sync:50,debug:0,burst:7,led:0,wide:1,settle:2,diff:0,irqm:0
 888
 889For an installation diskette or a safe but not fast system,
 890boot setup can be:
 891
 892    ncr53c8xx=safe:y,mpar:y,disc:y
 893    ncr53c8xx=safe:y,disc:y
 894    ncr53c8xx=safe:y,mpar:y
 895    ncr53c8xx=safe:y
 896
 897My personal system works flawlessly with the following equivalent setup:
 898
 899   ncr53c8xx=mpar:y,spar:y,disc:y,specf:1,fsn:n,ultra:2,fsn:n,revprob:n,verb:1\
 900             tags:32,sync:12,debug:0,burst:7,led:1,wide:1,settle:2,diff:0,irqm:0
 901
 902The driver prints its actual setup when verbosity level is 2. You can try 
 903"ncr53c8xx=verb:2" to get the "static" setup of the driver, or add "verb:2" 
 904to your boot setup command in order to check the actual setup the driver is 
 905using.
 906
 90710.4 PCI configuration fix-up boot option
 908
 909pcifix:<option bits>
 910
 911Available option bits:
 912    0x1:     Set PCI cache-line size register if not set.
 913    0x2:     Set write and invalidate bit in PCI command register.
 914
 915Use 'pcifix:3' in order to allow the driver to fix both PCI features.
 916
 917These options only apply to new SYMBIOS chips 810A, 825A, 860, 875 
 918and 895 and are only supported for Pentium and 486 class processors.
 919Recent SYMBIOS 53C8XX scsi processors are able to use PCI read multiple 
 920and PCI write and invalidate commands. These features require the 
 921cache line size register to be properly set in the PCI configuration 
 922space of the chips. On the other hand, chips will use PCI write and 
 923invalidate commands only if the corresponding bit is set to 1 in the 
 924PCI command register.
 925
 926Not all PCI bioses set the PCI cache line register and the PCI write and 
 927invalidate bit in the PCI configuration space of 53C8XX chips.
 928Optimized PCI accesses may be broken for some PCI/memory controllers or 
 929make problems with some PCI boards.
 930
 931This fix-up worked flawlessly on my previous system.
 932(MB Triton HX / 53C875 / 53C810A)
 933I use these options at my own risks as you will do if you decide to 
 934use them too.
 935
 936
 93710.5 Serial NVRAM support boot option
 938
 939nvram:n     do not look for serial NVRAM
 940nvram:y     test controllers for onboard serial NVRAM
 941
 942This option can also been entered as an hexadecimal value that allows 
 943to control what information the driver will get from the NVRAM and what 
 944information it will ignore.
 945For details see '17. Serial NVRAM support'.
 946
 947When this option is enabled, the driver tries to detect all boards using 
 948a Serial NVRAM. This memory is used to hold user set up parameters.
 949
 950The parameters the driver is able to get from the NVRAM depend on the 
 951data format used, as follow:
 952
 953                                 Tekram format      Symbios format
 954General and host parameters
 955    Boot order                         N                   Y
 956    Host SCSI ID                       Y                   Y
 957    SCSI parity checking               Y                   Y
 958    Verbose boot messages              N                   Y
 959SCSI devices parameters
 960    Synchronous transfer speed         Y                   Y
 961    Wide 16 / Narrow                   Y                   Y
 962    Tagged Command Queuing enabled     Y                   Y
 963    Disconnections enabled             Y                   Y
 964    Scan at boot time                  N                   Y
 965
 966In order to speed up the system boot, for each device configured without 
 967the "scan at boot time" option, the driver forces an error on the 
 968first TEST UNIT READY command received for this device.
 969
 970Some SDMS BIOS revisions seem to be unable to boot cleanly with very fast 
 971hard disks. In such a situation you cannot configure the NVRAM with 
 972optimized parameters value.
 973
 974The 'nvram' boot option can be entered in hexadecimal form in order 
 975to ignore some options configured in the NVRAM, as follow:
 976
 977mvram=<bits options>
 978      0x01   look for NVRAM  (equivalent to nvram=y)
 979      0x02   ignore NVRAM "Synchronous negotiation" parameters for all devices
 980      0x04   ignore NVRAM "Wide negotiation"  parameter for all devices
 981      0x08   ignore NVRAM "Scan at boot time" parameter for all devices
 982      0x80   also attach controllers set to OFF in the NVRAM (sym53c8xx only)
 983
 984Option 0x80 is only supported by the sym53c8xx driver and is disabled by 
 985default. Result is that, by default (option not set), the sym53c8xx driver 
 986will not attach controllers set to OFF in the NVRAM.
 987
 988The ncr53c8xx always tries to attach all the controllers. Option 0x80 has 
 989not been added to the ncr53c8xx driver, since it has been reported to 
 990confuse users who use this driver since a long time. If you desire a 
 991controller not to be attached by the ncr53c8xx driver at Linux boot, you 
 992must use the 'excl' driver boot option.
 993
 99410.6 SCSI BUS checking boot option.
 995
 996When this option is set to a non-zero value, the driver checks SCSI lines 
 997logic state, 100 micro-seconds after having asserted the SCSI RESET line.
 998The driver just reads SCSI lines and checks all lines read FALSE except RESET.
 999Since SCSI devices shall release the BUS at most 800 nano-seconds after SCSI 
1000RESET has been asserted, any signal to TRUE may indicate a SCSI BUS problem.
1001Unfortunately, the following common SCSI BUS problems are not detected:
1002- Only 1 terminator installed.
1003- Misplaced terminators.
1004- Bad quality terminators.
1005On the other hand, either bad cabling, broken devices, not conformant 
1006devices, ... may cause a SCSI signal to be wrong when te driver reads it.
1007
100810.7 IMMEDIATE ARBITRATION boot option
1009
1010This option is only supported by the SYM53C8XX driver (not by the NCR53C8XX).
1011
1012SYMBIOS 53C8XX chips are able to arbitrate for the SCSI BUS as soon as they 
1013have detected an expected disconnection (BUS FREE PHASE). For this process 
1014to be started, bit 1 of SCNTL1 IO register must be set when the chip is 
1015connected to the SCSI BUS.
1016
1017When this feature has been enabled for the current connection, the chip has 
1018every chance to win arbitration if only devices with lower priority are 
1019competing for the SCSI BUS. By the way, when the chip is using SCSI id 7, 
1020then it will for sure win the next SCSI BUS arbitration.
1021
1022Since, there is no way to know what devices are trying to arbitrate for the 
1023BUS, using this feature can be extremely unfair. So, you are not advised
1024to enable it, or at most enable this feature for the case the chip lost 
1025the previous arbitration (boot option 'iarb:1').
1026
1027This feature has the following advantages:
1028
1029a) Allow the initiator with ID 7 to win arbitration when it wants so.
1030b) Overlap at least 4 micro-seconds of arbitration time with the execution 
1031   of SCRIPTS that deal with the end of the current connection and that 
1032   starts the next job.
1033
1034Hmmm... But (a) may just prevent other devices from reselecting the initiator, 
1035and delay data transfers or status/completions, and (b) may just waste 
1036SCSI BUS bandwidth if the SCRIPTS execution lasts more than 4 micro-seconds.
1037
1038The use of IARB needs the SCSI_NCR_IARB_SUPPORT option to have been defined 
1039at compile time and the 'iarb' boot option to have been set to a non zero 
1040value at boot time. It is not that useful for real work, but can be used 
1041to stress SCSI devices or for some applications that can gain advantage of 
1042it. By the way, if you experience badnesses like 'unexpected disconnections', 
1043'bad reselections', etc... when using IARB on heavy IO load, you should not 
1044be surprised, because force-feeding anything and blocking its arse at the 
1045same time cannot work for a long time. :-))
1046
1047
104811. Some constants and flags of the ncr53c8xx.h header file
1049
1050Some of these are defined from the configuration parameters.  To
1051change other "defines", you must edit the header file.  Do that only
1052if you know what you are doing.
1053
1054SCSI_NCR_SETUP_SPECIAL_FEATURES (default: defined)
1055        If defined, the driver will enable some special features according  
1056        to chip and revision id.
1057        For 810A, 860, 825A, 875 and 895 scsi chips, this option enables 
1058        support of features that reduce load of PCI bus and memory accesses 
1059        during  scsi transfer processing: burst op-code fetch, read multiple, 
1060        read line, prefetch, cache line, write and invalidate, 
1061        burst 128 (875 only), large dma fifo (875 only), offset 16 (875 only).
1062        Can be changed by the following boot setup command:
1063                ncr53c8xx=specf:n
1064
1065SCSI_NCR_IOMAPPED               (default: not defined)
1066        If defined, normal I/O is forced.
1067
1068SCSI_NCR_SHARE_IRQ              (default: defined)
1069        If defined, request shared IRQ.
1070        
1071SCSI_NCR_MAX_TAGS               (default: 8)
1072        Maximum number of simultaneous tagged commands to a device.
1073        Can be changed by "settags <target> <maxtags>"
1074
1075SCSI_NCR_SETUP_DEFAULT_SYNC     (default: 50)
1076        Transfer period factor the driver will use at boot time for synchronous 
1077        negotiation. 0 means asynchronous.
1078        Can be changed by "setsync <target> <period factor>"
1079
1080SCSI_NCR_SETUP_DEFAULT_TAGS     (default: 8)
1081        Default number of simultaneous tagged commands to a device.
1082        < 1 means tagged command queuing disabled at start-up.
1083
1084SCSI_NCR_ALWAYS_SIMPLE_TAG      (default: defined)
1085        Use SIMPLE TAG for read and write commands.
1086        Can be changed by "setorder <ordered|simple|default>"
1087
1088SCSI_NCR_SETUP_DISCONNECTION    (default: defined)
1089        If defined, targets are allowed to disconnect.
1090
1091SCSI_NCR_SETUP_FORCE_SYNC_NEGO  (default: not defined)
1092        If defined, synchronous negotiation is tried for all SCSI-2 devices.
1093        Can be changed by "setsync <target> <period>"
1094
1095SCSI_NCR_SETUP_MASTER_PARITY    (default: defined)
1096        If defined, master parity checking is enabled.
1097
1098SCSI_NCR_SETUP_MASTER_PARITY    (default: defined)
1099        If defined, SCSI parity checking is enabled.
1100
1101SCSI_NCR_PROFILE_SUPPORT        (default: not defined)
1102        If defined, profiling information is gathered.
1103
1104SCSI_NCR_MAX_SCATTER            (default: 128)
1105        Scatter list size of the driver ccb.
1106
1107SCSI_NCR_MAX_TARGET             (default: 16)
1108        Max number of targets per host.
1109
1110SCSI_NCR_MAX_HOST               (default: 2)
1111        Max number of host controllers.
1112
1113SCSI_NCR_SETTLE_TIME            (default: 2)
1114        Number of seconds the driver will wait after reset.
1115
1116SCSI_NCR_TIMEOUT_ALERT          (default: 3)
1117        If a pending command will time out after this amount of seconds,
1118        an ordered tag is used for the next command.
1119        Avoids timeouts for unordered tagged commands.
1120
1121SCSI_NCR_CAN_QUEUE              (default: 7*SCSI_NCR_MAX_TAGS)
1122        Max number of commands that can be queued to a host.
1123
1124SCSI_NCR_CMD_PER_LUN            (default: SCSI_NCR_MAX_TAGS)
1125        Max number of commands queued to a host for a device.
1126
1127SCSI_NCR_SG_TABLESIZE           (default: SCSI_NCR_MAX_SCATTER-1)
1128        Max size of the Linux scatter/gather list.
1129
1130SCSI_NCR_MAX_LUN        (default: 8)
1131        Max number of LUNs per target.
1132
1133
113412. Installation
1135
1136This driver is part of the linux kernel distribution.
1137Driver files are located in the sub-directory "drivers/scsi" of the 
1138kernel source tree.
1139
1140Driver files:
1141
1142        README.ncr53c8xx        : this file
1143        ChangeLog.ncr53c8xx     : change log
1144        ncr53c8xx.h             : definitions
1145        ncr53c8xx.c             : the driver code
1146
1147New driver versions are made available separately in order to allow testing 
1148changes and new features prior to including them into the linux kernel 
1149distribution. The following URL provides information on latest available 
1150patches: 
1151
1152      ftp://ftp.tux.org/pub/people/gerard-roudier/README
1153
1154
115513. Architecture dependent features.
1156
1157<Not yet written>
1158
1159
116014. Known problems
1161
116214.1 Tagged commands with Iomega Jaz device
1163
1164I have not tried this device, however it has been reported to me the
1165following: This device is capable of Tagged command queuing. However
1166while spinning up, it rejects Tagged commands. This behaviour is
1167conforms to 6.8.2 of SCSI-2 specifications. The current behaviour of
1168the driver in that situation is not satisfying. So do not enable
1169Tagged command queuing for devices that are able to spin down.  The
1170other problem that may appear is timeouts. The only way to avoid
1171timeouts seems to edit linux/drivers/scsi/sd.c and to increase the
1172current timeout values.
1173
117414.2 Device names change when another controller is added.
1175
1176When you add a new NCR53C8XX chip based controller to a system that already 
1177has one or more controllers of this family, it may happen that the order 
1178the driver registers them to the kernel causes problems due to device 
1179name changes.
1180When at least one controller uses NvRAM, SDMS BIOS version 4 allows you to 
1181define the order the BIOS will scan the scsi boards. The driver attaches 
1182controllers according to BIOS information if NvRAM detect option is set.
1183
1184If your controllers do not have NvRAM, you can:
1185
1186- Ask the driver to probe chip ids in reverse order from the boot command
1187  line: ncr53c8xx=revprob:y
1188- Make appropriate changes in the fstab.
1189- Use the 'scsidev' tool from Eric Youngdale.
1190
119114.3 Using only 8 bit devices with a WIDE SCSI controller.
1192
1193When only 8 bit NARROW devices are connected to a 16 bit WIDE SCSI controller, 
1194you must ensure that lines of the wide part of the SCSI BUS are pulled-up.
1195This can be achieved by ENABLING the WIDE TERMINATOR portion of the SCSI 
1196controller card.
1197The TYAN 1365 documentation revision 1.2 is not correct about such settings.
1198(page 10, figure 3.3).
1199
120014.4 Possible data corruption during a Memory Write and Invalidate
1201
1202This problem is described in SYMBIOS DEL 397, Part Number 69-039241, ITEM 4.
1203
1204In some complex situations, 53C875 chips revision <= 3 may start a PCI 
1205Write and Invalidate Command at a not cache-line-aligned 4 DWORDS boundary.
1206This is only possible when Cache Line Size is 8 DWORDS or greater.
1207Pentium systems use a 8 DWORDS cache line size and so are concerned by 
1208this chip bug, unlike i486 systems that use a 4 DWORDS cache line size.
1209
1210When this situation occurs, the chip may complete the Write and Invalidate 
1211command after having only filled part of the last cache line involved in 
1212the transfer, leaving to data corruption the remainder of this cache line.
1213
1214Not using Write And Invalidate obviously gets rid of this chip bug, and so 
1215it is now the default setting of the driver.
1216However, for people like me who want to enable this feature, I have added 
1217part of a work-around suggested by SYMBIOS. This work-around resets the 
1218addressing logic when the DATA IN phase is entered and so prevents the bug 
1219from being triggered for the first SCSI MOVE of the phase. This work-around 
1220should be enough according to the following:
1221
1222The only driver internal data structure that is greater than 8 DWORDS  and 
1223that is moved by the SCRIPTS processor is the 'CCB header' that contains 
1224the context of the SCSI transfer. This data structure is aligned on 8 DWORDS 
1225boundary (Pentium Cache Line Size), and so is immune to this chip bug, at 
1226least on Pentium systems.
1227But the conditions of this bug can be met when a SCSI read command is 
1228performed using a buffer that is 4 DWORDS but not cache-line aligned.
1229This cannot happen under Linux when scatter/gather lists are used since 
1230they only refer to system buffers that are well aligned. So, a work around 
1231may only be needed under Linux when a scatter/gather list is not used and 
1232when the SCSI DATA IN phase is reentered after a phase mismatch.
1233
123414.5 IRQ sharing problems
1235
1236When an IRQ is shared by devices that are handled by different drivers, it 
1237may happen that one driver complains about the request of the IRQ having 
1238failed. Inder Linux-2.0, this may be due to one driver having requested the 
1239IRQ using the IRQF_DISABLED flag but some other having requested the same IRQ
1240without this flag. Under both Linux-2.0 and linux-2.2, this may be caused by 
1241one driver not having requested the IRQ with the IRQF_SHARED flag.
1242
1243By default, the ncr53c8xx and sym53c8xx drivers request IRQs with both the 
1244IRQF_DISABLED and the IRQF_SHARED flag under Linux-2.0 and with only the IRQF_SHARED
1245flag under Linux-2.2.
1246
1247Under Linux-2.0, you can disable use of IRQF_DISABLED flag from the boot
1248command line by using the following option:
1249
1250     ncr53c8xx=irqm:0x20   (for the generic ncr53c8xx driver)
1251     sym53c8xx=irqm:0x20   (for the sym53c8xx driver)
1252
1253If this does not fix the problem, then you may want to check how all other 
1254drivers are requesting the IRQ and report the problem. Note that if at least 
1255a single driver does not request the IRQ with the IRQF_SHARED flag (share IRQ),
1256then the request of the IRQ obviously will not succeed for all the drivers.
1257
125815. SCSI problem troubleshooting
1259
126015.1 Problem tracking
1261
1262Most SCSI problems are due to a non conformant SCSI bus or to buggy
1263devices.  If unfortunately you have SCSI problems, you can check the
1264following things:
1265
1266- SCSI bus cables
1267- terminations at both end of the SCSI chain
1268- linux syslog messages (some of them may help you)
1269
1270If you do not find the source of problems, you can configure the
1271driver with no features enabled.
1272
1273- only asynchronous data transfers
1274- tagged commands disabled
1275- disconnections not allowed
1276
1277Now, if your SCSI bus is ok, your system have every chance to work
1278with this safe configuration but performances will not be optimal.
1279
1280If it still fails, then you can send your problem description to
1281appropriate mailing lists or news-groups.  Send me a copy in order to
1282be sure I will receive it.  Obviously, a bug in the driver code is
1283possible.
1284
1285     My email address: Gerard Roudier <groudier@free.fr>
1286
1287Allowing disconnections is important if you use several devices on
1288your SCSI bus but often causes problems with buggy devices.
1289Synchronous data transfers increases throughput of fast devices like
1290hard disks.  Good SCSI hard disks with a large cache gain advantage of
1291tagged commands queuing.
1292
1293Try to enable one feature at a time with control commands.  For example:
1294
1295- echo "setsync all 25" >/proc/scsi/ncr53c8xx/0
1296  Will enable fast synchronous data transfer negotiation for all targets.
1297
1298- echo "setflag 3" >/proc/scsi/ncr53c8xx/0
1299  Will reset flags (no_disc) for target 3, and so will allow it to disconnect 
1300  the SCSI Bus.
1301
1302- echo "settags 3 8" >/proc/scsi/ncr53c8xx/0
1303  Will enable tagged command queuing for target 3 if that device supports it.
1304
1305Once you have found the device and the feature that cause problems, just 
1306disable that feature for that device.
1307
130815.2 Understanding hardware error reports
1309
1310When the driver detects an unexpected error condition, it may display a 
1311message of the following pattern.
1312
1313sym53c876-0:1: ERROR (0:48) (1-21-65) (f/95) @ (script 7c0:19000000).
1314sym53c876-0: script cmd = 19000000
1315sym53c876-0: regdump: da 10 80 95 47 0f 01 07 75 01 81 21 80 01 09 00.
1316
1317Some fields in such a message may help you understand the cause of the 
1318problem, as follows:
1319
1320sym53c876-0:1: ERROR (0:48) (1-21-65) (f/95) @ (script 7c0:19000000).
1321............A.........B.C....D.E..F....G.H.......I.....J...K.......
1322
1323Field A : target number.
1324  SCSI ID of the device the controller was talking with at the moment the 
1325  error occurs.
1326
1327Field B : DSTAT io register (DMA STATUS)
1328  Bit 0x40 : MDPE Master Data Parity Error
1329             Data parity error detected on the PCI BUS.
1330  Bit 0x20 : BF   Bus Fault
1331             PCI bus fault condition detected
1332  Bit 0x01 : IID  Illegal Instruction Detected
1333             Set by the chip when it detects an Illegal Instruction format 
1334             on some condition that makes an instruction illegal.
1335  Bit 0x80 : DFE Dma Fifo Empty
1336             Pure status bit that does not indicate an error.
1337  If the reported DSTAT value contains a combination of MDPE (0x40), 
1338  BF (0x20), then the cause may be likely due to a PCI BUS problem.
1339
1340Field C : SIST io register (SCSI Interrupt Status)
1341  Bit 0x08 : SGE  SCSI GROSS ERROR
1342             Indicates that the chip detected a severe error condition 
1343             on the SCSI BUS that prevents the SCSI protocol from functioning
1344             properly.
1345  Bit 0x04 : UDC  Unexpected Disconnection
1346             Indicates that the device released the SCSI BUS when the chip 
1347             was not expecting this to happen. A device may behave so to 
1348             indicate the SCSI initiator that an error condition not reportable              using the SCSI protocol has occurred.
1349  Bit 0x02 : RST  SCSI BUS Reset
1350             Generally SCSI targets do not reset the SCSI BUS, although any 
1351             device on the BUS can reset it at any time.
1352  Bit 0x01 : PAR  Parity
1353             SCSI parity error detected.
1354  On a faulty SCSI BUS, any error condition among SGE (0x08), UDC (0x04) and 
1355  PAR (0x01) may be detected by the chip. If your SCSI system sometimes 
1356  encounters such error conditions, especially SCSI GROSS ERROR, then a SCSI 
1357  BUS problem is likely the cause of these errors.
1358
1359For fields D,E,F,G and H, you may look into the sym53c8xx_defs.h file 
1360that contains some minimal comments on IO register bits.
1361Field D : SOCL  Scsi Output Control Latch
1362          This register reflects the state of the SCSI control lines the 
1363          chip want to drive or compare against.
1364Field E : SBCL  Scsi Bus Control Lines
1365          Actual value of control lines on the SCSI BUS.
1366Field F : SBDL  Scsi Bus Data Lines
1367          Actual value of data lines on the SCSI BUS.
1368Field G : SXFER  SCSI Transfer
1369          Contains the setting of the Synchronous Period for output and 
1370          the current Synchronous offset (offset 0 means asynchronous).
1371Field H : SCNTL3 Scsi Control Register 3
1372          Contains the setting of timing values for both asynchronous and 
1373          synchronous data transfers. 
1374
1375Understanding Fields I, J, K and dumps requires to have good knowledge of 
1376SCSI standards, chip cores functionnals and internal driver data structures.
1377You are not required to decode and understand them, unless you want to help 
1378maintain the driver code.
1379
138016. Synchronous transfer negotiation tables
1381
1382Tables below have been created by calling the routine the driver uses
1383for synchronisation negotiation timing calculation and chip setting.
1384The first table corresponds to Ultra chips 53875 and 53C860 with 80 MHz 
1385clock and 5 clock divisors.
1386The second one has been calculated by setting the scsi clock to 40 Mhz 
1387and using 4 clock divisors and so applies to all NCR53C8XX chips in fast 
1388SCSI-2 mode.
1389
1390Periods are in nano-seconds and speeds are in Mega-transfers per second.
13911 Mega-transfers/second means 1 MB/s with 8 bits SCSI and 2 MB/s with 
1392Wide16 SCSI.
1393
139416.1 Synchronous timings for 53C895, 53C875 and 53C860 SCSI controllers
1395
1396 ----------------------------------------------
1397 Negotiated                     NCR settings
1398 Factor   Period   Speed        Period   Speed
1399 ------   ------   ------       ------   ------
1400 10       25       40.000       25       40.000   (53C895 only)
1401 11       30.2     33.112       31.25    32.000   (53C895 only)
1402 12       50       20.000       50       20.000
1403 13       52       19.230       62       16.000
1404 14       56       17.857       62       16.000
1405 15       60       16.666       62       16.000
1406 16       64       15.625       75       13.333
1407 17       68       14.705       75       13.333
1408 18       72       13.888       75       13.333
1409 19       76       13.157       87       11.428
1410 20       80       12.500       87       11.428
1411 21       84       11.904       87       11.428
1412 22       88       11.363       93       10.666
1413 23       92       10.869       93       10.666
1414 24       96       10.416      100       10.000
1415 25      100       10.000      100       10.000
1416 26      104        9.615      112        8.888
1417 27      108        9.259      112        8.888
1418 28      112        8.928      112        8.888
1419 29      116        8.620      125        8.000
1420 30      120        8.333      125        8.000
1421 31      124        8.064      125        8.000
1422 32      128        7.812      131        7.619
1423 33      132        7.575      150        6.666
1424 34      136        7.352      150        6.666
1425 35      140        7.142      150        6.666
1426 36      144        6.944      150        6.666
1427 37      148        6.756      150        6.666
1428 38      152        6.578      175        5.714
1429 39      156        6.410      175        5.714
1430 40      160        6.250      175        5.714
1431 41      164        6.097      175        5.714
1432 42      168        5.952      175        5.714
1433 43      172        5.813      175        5.714
1434 44      176        5.681      187        5.333
1435 45      180        5.555      187        5.333
1436 46      184        5.434      187        5.333
1437 47      188        5.319      200        5.000
1438 48      192        5.208      200        5.000
1439 49      196        5.102      200        5.000
1440
1441
144216.2 Synchronous timings for fast SCSI-2 53C8XX controllers
1443
1444 ----------------------------------------------
1445 Negotiated                     NCR settings
1446 Factor   Period   Speed        Period   Speed
1447 ------   ------   ------       ------   ------
1448 25      100       10.000      100       10.000
1449 26      104        9.615      125        8.000
1450 27      108        9.259      125        8.000
1451 28      112        8.928      125        8.000
1452 29      116        8.620      125        8.000
1453 30      120        8.333      125        8.000
1454 31      124        8.064      125        8.000
1455 32      128        7.812      131        7.619
1456 33      132        7.575      150        6.666
1457 34      136        7.352      150        6.666
1458 35      140        7.142      150        6.666
1459 36      144        6.944      150        6.666
1460 37      148        6.756      150        6.666
1461 38      152        6.578      175        5.714
1462 39      156        6.410      175        5.714
1463 40      160        6.250      175        5.714
1464 41      164        6.097      175        5.714
1465 42      168        5.952      175        5.714
1466 43      172        5.813      175        5.714
1467 44      176        5.681      187        5.333
1468 45      180        5.555      187        5.333
1469 46      184        5.434      187        5.333
1470 47      188        5.319      200        5.000
1471 48      192        5.208      200        5.000
1472 49      196        5.102      200        5.000
1473
1474
147517. Serial NVRAM (added by Richard Waltham: dormouse@farsrobt.demon.co.uk)
1476
147717.1 Features
1478
1479Enabling serial NVRAM support enables detection of the serial NVRAM included
1480on Symbios and some Symbios compatible host adaptors, and Tekram boards. The 
1481serial NVRAM is used by Symbios and Tekram to hold set up parameters for the 
1482host adaptor and its attached drives.
1483
1484The Symbios NVRAM also holds data on the boot order of host adaptors in a
1485system with more than one host adaptor. This enables the order of scanning
1486the cards for drives to be changed from the default used during host adaptor
1487detection.
1488
1489This can be done to a limited extent at the moment using "reverse probe" but
1490this only changes the order of detection of different types of cards. The
1491NVRAM boot order settings can do this as well as change the order the same
1492types of cards are scanned in, something "reverse probe" cannot do.
1493
1494Tekram boards using Symbios chips, DC390W/F/U, which have NVRAM are detected
1495and this is used to distinguish between Symbios compatible and Tekram host 
1496adaptors. This is used to disable the Symbios compatible "diff" setting
1497incorrectly set on Tekram boards if the CONFIG_SCSI_53C8XX_SYMBIOS_COMPAT 
1498configuration parameter is set enabling both Symbios and Tekram boards to be 
1499used together with the Symbios cards using all their features, including
1500"diff" support. ("led pin" support for Symbios compatible cards can remain
1501enabled when using Tekram cards. It does nothing useful for Tekram host
1502adaptors but does not cause problems either.)
1503
1504
150517.2 Symbios NVRAM layout
1506
1507typical data at NVRAM address 0x100 (53c810a NVRAM)
1508-----------------------------------------------------------
150900 00
151064 01
15118e 0b
1512
151300 30 00 00 00 00 07 00 00 00 00 00 00 00 07 04 10 04 00 00 
1514
151504 00 0f 00 00 10 00 50 00 00 01 00 00 62 
151604 00 03 00 00 10 00 58 00 00 01 00 00 63 
151704 00 01 00 00 10 00 48 00 00 01 00 00 61 
151800 00 00 00 00 00 00 00 00 00 00 00 00 00 
1519
15200f 00 08 08 64 00 0a 00
15210f 00 08 08 64 00 0a 00 
15220f 00 08 08 64 00 0a 00 
15230f 00 08 08 64 00 0a 00 
15240f 00 08 08 64 00 0a 00 
15250f 00 08 08 64 00 0a 00 
15260f 00 08 08 64 00 0a 00 
15270f 00 08 08 64 00 0a 00 
1528
15290f 00 08 08 64 00 0a 00 
15300f 00 08 08 64 00 0a 00 
15310f 00 08 08 64 00 0a 00 
15320f 00 08 08 64 00 0a 00 
15330f 00 08 08 64 00 0a 00 
15340f 00 08 08 64 00 0a 00 
15350f 00 08 08 64 00 0a 00 
15360f 00 08 08 64 00 0a 00 
1537
153800 00 00 00 00 00 00 00 
153900 00 00 00 00 00 00 00 
154000 00 00 00 00 00 00 00 
154100 00 00 00 00 00 00 00 
154200 00 00 00 00 00 00 00 
154300 00 00 00 00 00 00 00 
154400 00 00 00 00 00 00 00 
154500 00 00 00 00 00 00 00 
1546
154700 00 00 00 00 00 00 00 
154800 00 00 00 00 00 00 00 
154900 00 00 00 00 00 00 00 
155000 00 00 00 00 00 00 00 
155100 00 00 00 00 00 00 00 
155200 00 00 00 00 00 00 00 
155300 00 00 00 00 00 00 00 
155400 00 00 00 00 00 00 00 
1555
155600 00 00 00 00 00 00 00 
155700 00 00 00 00 00 00 00 
155800 00 00 00 00 00 00 00 
1559
1560fe fe
156100 00
156200 00
1563-----------------------------------------------------------
1564NVRAM layout details
1565
1566NVRAM Address 0x000-0x0ff not used
1567              0x100-0x26f initialised data
1568              0x270-0x7ff not used
1569
1570general layout
1571
1572        header  -   6 bytes,
1573        data    - 356 bytes (checksum is byte sum of this data)
1574        trailer -   6 bytes
1575                  ---
1576        total     368 bytes
1577
1578data area layout
1579
1580        controller set up  -  20 bytes
1581        boot configuration -  56 bytes (4x14 bytes)
1582        device set up      - 128 bytes (16x8 bytes)
1583        unused (spare?)    - 152 bytes (19x8 bytes)
1584                             ---
1585        total                356 bytes
1586
1587-----------------------------------------------------------
1588header
1589
159000 00   - ?? start marker
159164 01   - byte count (lsb/msb excludes header/trailer)
15928e 0b   - checksum (lsb/msb excludes header/trailer)
1593-----------------------------------------------------------
1594controller set up
1595
159600 30 00 00 00 00 07 00 00 00 00 00 00 00 07 04 10 04 00 00
1597                   |     |           |     |
1598                   |     |           |      -- host ID
1599                   |     |           |
1600                   |     |            --Removable Media Support
1601                   |     |               0x00 = none
1602                   |     |               0x01 = Bootable Device
1603                   |     |               0x02 = All with Media
1604                   |     |
1605                   |      --flag bits 2
1606                   |        0x00000001= scan order hi->low
1607                   |            (default 0x00 - scan low->hi)
1608                    --flag bits 1
1609                       0x00000001 scam enable
1610                       0x00000010 parity enable
1611                       0x00000100 verbose boot msgs
1612
1613remaining bytes unknown - they do not appear to change in my
1614current set up for any of the controllers.
1615
1616default set up is identical for 53c810a and 53c875 NVRAM
1617(Removable Media added Symbios BIOS version 4.09)
1618-----------------------------------------------------------
1619boot configuration
1620
1621boot order set by order of the devices in this table
1622
162304 00 0f 00 00 10 00 50 00 00 01 00 00 62 -- 1st controller
162404 00 03 00 00 10 00 58 00 00 01 00 00 63    2nd controller
162504 00 01 00 00 10 00 48 00 00 01 00 00 61    3rd controller
162600 00 00 00 00 00 00 00 00 00 00 00 00 00    4th controller
1627       |  |  |  |     |        |     |  |
1628       |  |  |  |     |        |      ---- PCI io port adr
1629       |  |  |  |     |         --0x01 init/scan at boot time
1630       |  |  |  |      --PCI device/function number (0xdddddfff)
1631       |  |   ----- ?? PCI vendor ID (lsb/msb)
1632        ----PCI device ID (lsb/msb)
1633
1634?? use of this data is a guess but seems reasonable
1635
1636remaining bytes unknown - they do not appear to change in my
1637current set up
1638
1639default set up is identical for 53c810a and 53c875 NVRAM
1640-----------------------------------------------------------
1641device set up (up to 16 devices - includes controller)
1642
16430f 00 08 08 64 00 0a 00 - id 0
16440f 00 08 08 64 00 0a 00 
16450f 00 08 08 64 00 0a 00 
16460f 00 08 08 64 00 0a 00 
16470f 00 08 08 64 00 0a 00 
16480f 00 08 08 64 00 0a 00 
16490f 00 08 08 64 00 0a 00 
16500f 00 08 08 64 00 0a 00 
1651
16520f 00 08 08 64 00 0a 00 
16530f 00 08 08 64 00 0a 00 
16540f 00 08 08 64 00 0a 00 
16550f 00 08 08 64 00 0a 00 
16560f 00 08 08 64 00 0a 00 
16570f 00 08 08 64 00 0a 00 
16580f 00 08 08 64 00 0a 00 
16590f 00 08 08 64 00 0a 00 - id 15
1660 |     |  |  |     |  |
1661 |     |  |  |      ----timeout (lsb/msb)
1662 |     |  |   --synch period (0x?? 40 Mtrans/sec- fast 40) (probably 0x28)
1663 |     |  |                  (0x30 20 Mtrans/sec- fast 20)
1664 |     |  |                  (0x64 10 Mtrans/sec- fast )
1665 |     |  |                  (0xc8  5 Mtrans/sec)
1666 |     |  |                  (0x00  asynchronous)
1667 |     |   -- ?? max sync offset (0x08 in NVRAM on 53c810a) 
1668 |     |                         (0x10 in NVRAM on 53c875)
1669 |      --device bus width (0x08 narrow)
1670 |                         (0x10 16 bit wide)
1671  --flag bits
1672    0x00000001 - disconnect enabled
1673    0x00000010 - scan at boot time
1674    0x00000100 - scan luns
1675    0x00001000 - queue tags enabled
1676
1677remaining bytes unknown - they do not appear to change in my
1678current set up
1679
1680?? use of this data is a guess but seems reasonable 
1681(but it could be max bus width)
1682
1683default set up for 53c810a NVRAM
1684default set up for 53c875 NVRAM - bus width     - 0x10
1685                                - sync offset ? - 0x10
1686                                - sync period   - 0x30
1687-----------------------------------------------------------
1688?? spare device space (32 bit bus ??)
1689
169000 00 00 00 00 00 00 00  (19x8bytes)
1691.
1692.
169300 00 00 00 00 00 00 00
1694
1695default set up is identical for 53c810a and 53c875 NVRAM
1696-----------------------------------------------------------
1697trailer
1698
1699fe fe   - ? end marker ?
170000 00
170100 00
1702
1703default set up is identical for 53c810a and 53c875 NVRAM
1704-----------------------------------------------------------
1705
1706
1707
170817.3 Tekram NVRAM layout
1709
1710nvram 64x16 (1024 bit)
1711
1712Drive settings
1713
1714Drive ID 0-15 (addr 0x0yyyy0 = device setup, yyyy = ID)
1715              (addr 0x0yyyy1 = 0x0000)
1716
1717    x x x x  x x x x  x x x x  x x x x
1718               | | |      | |  | | | |
1719               | | |      | |  | | |  ----- parity check   0 - off
1720               | | |      | |  | | |                       1 - on
1721               | | |      | |  | | |
1722               | | |      | |  | |  ------- sync neg       0 - off
1723               | | |      | |  | |                         1 - on
1724               | | |      | |  | |
1725               | | |      | |  |  --------- disconnect     0 - off
1726               | | |      | |  |                           1 - on
1727               | | |      | |  |
1728               | | |      | |   ----------- start cmd      0 - off
1729               | | |      | |                              1 - on
1730               | | |      | |
1731               | | |      |  -------------- tagged cmds    0 - off
1732               | | |      |                                1 - on
1733               | | |      | 
1734               | | |       ---------------- wide neg       0 - off
1735               | | |                                       1 - on
1736               | | |
1737                --------------------------- sync rate      0 - 10.0 Mtrans/sec
1738                                                           1 -  8.0
1739                                                           2 -  6.6
1740                                                           3 -  5.7
1741                                                           4 -  5.0
1742                                                           5 -  4.0
1743                                                           6 -  3.0
1744                                                           7 -  2.0
1745                                                           7 -  2.0
1746                                                           8 - 20.0
1747                                                           9 - 16.7
1748                                                           a - 13.9
1749                                                           b - 11.9
1750
1751Global settings
1752
1753Host flags 0 (addr 0x100000, 32) 
1754
1755    x x x x  x x x x  x x x x  x x x x
1756    | | | |  | | | |           | | | |
1757    | | | |  | | | |            ----------- host ID    0x00 - 0x0f
1758    | | | |  | | | |
1759    | | | |  | | |  ----------------------- support for    0 - off
1760    | | | |  | | |                          > 2 drives     1 - on
1761    | | | |  | | | 
1762    | | | |  | |  ------------------------- support drives 0 - off
1763    | | | |  | |                            > 1Gbytes      1 - on
1764    | | | |  | |
1765    | | | |  |  --------------------------- bus reset on   0 - off
1766    | | | |  |                                power on     1 - on
1767    | | | |  |
1768    | | | |   ----------------------------- active neg     0 - off
1769    | | | |                                                1 - on
1770    | | | |
1771    | | |  -------------------------------- imm seek       0 - off
1772    | | |                                                  1 - on
1773    | | |
1774    | |  ---------------------------------- scan luns      0 - off
1775    | |                                                    1 - on
1776    | |
1777     -------------------------------------- removable      0 - disable
1778                                            as BIOS dev    1 - boot device
1779                                                           2 - all
1780
1781Host flags 1 (addr 0x100001, 33)
1782
1783    x x x x  x x x x  x x x x  x x x x
1784               | | |             | | | 
1785               | | |              --------- boot delay     0 -   3 sec
1786               | | |                                       1 -   5
1787               | | |                                       2 -  10
1788               | | |                                       3 -  20
1789               | | |                                       4 -  30
1790               | | |                                       5 -  60
1791               | | |                                       6 - 120
1792               | | |
1793                --------------------------- max tag cmds   0 -  2
1794                                                           1 -  4
1795                                                           2 -  8
1796                                                           3 - 16
1797                                                           4 - 32
1798
1799Host flags 2 (addr 0x100010, 34)
1800
1801    x x x x  x x x x  x x x x  x x x x
1802                                     |
1803                                      ----- F2/F6 enable   0 - off ???
1804                                                           1 - on  ???
1805
1806checksum (addr 0x111111)
1807
1808checksum = 0x1234 - (sum addr 0-63)
1809
1810----------------------------------------------------------------------------
1811
1812default nvram data:
1813
18140x0037 0x0000 0x0037 0x0000 0x0037 0x0000 0x0037 0x0000
18150x0037 0x0000 0x0037 0x0000 0x0037 0x0000 0x0037 0x0000
18160x0037 0x0000 0x0037 0x0000 0x0037 0x0000 0x0037 0x0000
18170x0037 0x0000 0x0037 0x0000 0x0037 0x0000 0x0037 0x0000 
1818
18190x0f07 0x0400 0x0001 0x0000 0x0000 0x0000 0x0000 0x0000
18200x0000 0x0000 0x0000 0x0000 0x0000 0x0000 0x0000 0x0000
18210x0000 0x0000 0x0000 0x0000 0x0000 0x0000 0x0000 0x0000
18220x0000 0x0000 0x0000 0x0000 0x0000 0x0000 0x0000 0xfbbc
1823
1824
182518. Support for Big Endian
1826
1827The PCI local bus has been primarily designed for x86 architecture.
1828As a consequence, PCI devices generally expect DWORDS using little endian 
1829byte ordering.
1830
183118.1 Big Endian CPU
1832
1833In order to support NCR chips on a Big Endian architecture the driver has to 
1834perform byte reordering each time it is needed. This feature has been 
1835added to the driver by Cort <cort@cs.nmt.edu> and is available in driver 
1836version 2.5 and later ones. For the moment Big Endian support has only 
1837been tested on Linux/PPC (PowerPC).
1838
183918.2 NCR chip in Big Endian mode of operations
1840
1841It can be read in SYMBIOS documentation that some chips support a special 
1842Big Endian mode, on paper: 53C815, 53C825A, 53C875, 53C875N, 53C895.
1843This mode of operations is not software-selectable, but needs pin named 
1844BigLit to be pulled-up. Using this mode, most of byte reorderings should 
1845be avoided when the driver is running on a Big Endian CPU.
1846Driver version 2.5 is also, in theory, ready for this feature.
1847
1848===============================================================================
1849End of NCR53C8XX driver README file
1850
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