linux/Documentation/scsi/sym53c8xx_2.txt
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   1The Linux SYM-2 driver documentation file
   2
   3Written by Gerard Roudier <groudier@free.fr>
   421 Rue Carnot
   595170 DEUIL LA BARRE - FRANCE
   6
   7Updated by Matthew Wilcox <matthew@wil.cx>
   8
   92004-10-09
  10===============================================================================
  11
  121.  Introduction
  132.  Supported chips and SCSI features
  143.  Advantages of this driver for newer chips.
  15      3.1 Optimized SCSI SCRIPTS
  16      3.2 New features appeared with the SYM53C896
  174.  Memory mapped I/O versus normal I/O
  185.  Tagged command queueing
  196.  Parity checking
  207.  Profiling information
  218.  Control commands
  22      8.1  Set minimum synchronous period
  23      8.2  Set wide size
  24      8.3  Set maximum number of concurrent tagged commands
  25      8.4  Set debug mode
  26      8.5  Set flag (no_disc)
  27      8.6  Set verbose level
  28      8.7  Reset all logical units of a target
  29      8.8  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  Default number of tagged commands
  35             10.2.2  Burst max
  36             10.2.3  LED support
  37             10.2.4  Differential mode
  38             10.2.5  IRQ mode
  39             10.2.6  Check SCSI BUS 
  40             10.2.7  Suggest a default SCSI id for hosts
  41             10.2.8  Verbosity level
  42             10.2.9  Debug mode
  43             10.2.10 Settle delay
  44             10.2.11 Serial NVRAM
  45             10.2.12 Exclude a host from being attached
  46      10.3 Converting from old options
  47      10.4 SCSI BUS checking boot option
  4811. SCSI problem troubleshooting
  49      15.1 Problem tracking
  50      15.2 Understanding hardware error reports
  5112. Serial NVRAM support (by Richard Waltham)
  52      17.1 Features
  53      17.2 Symbios NVRAM layout
  54      17.3 Tekram  NVRAM layout
  55
  56===============================================================================
  57
  581. Introduction
  59
  60This driver supports the whole SYM53C8XX family of PCI-SCSI controllers.
  61It also support the subset of LSI53C10XX PCI-SCSI controllers that are based 
  62on the SYM53C8XX SCRIPTS language.
  63
  64It replaces the sym53c8xx+ncr53c8xx driver bundle and shares its core code 
  65with the FreeBSD SYM-2 driver. The `glue' that allows this driver to work 
  66under Linux is contained in 2 files named sym_glue.h and sym_glue.c.
  67Other drivers files are intended not to depend on the Operating System 
  68on which the driver is used.
  69
  70The history of this driver can be summarized as follows:
  71
  721993: ncr driver written for 386bsd and FreeBSD by:
  73          Wolfgang Stanglmeier        <wolf@cologne.de>
  74          Stefan Esser                <se@mi.Uni-Koeln.de>
  75
  761996: port of the ncr driver to Linux-1.2.13 and rename it ncr53c8xx.
  77          Gerard Roudier
  78
  791998: new sym53c8xx driver for Linux based on LOAD/STORE instruction and that 
  80      adds full support for the 896 but drops support for early NCR devices.
  81          Gerard Roudier
  82
  831999: port of the sym53c8xx driver to FreeBSD and support for the LSI53C1010 
  84      33 MHz and 66MHz Ultra-3 controllers. The new driver is named `sym'.
  85          Gerard Roudier
  86
  872000: Add support for early NCR devices to FreeBSD `sym' driver.
  88      Break the driver into several sources and separate the OS glue 
  89      code from the core code that can be shared among different O/Ses.
  90      Write a glue code for Linux.
  91          Gerard Roudier
  92
  932004: Remove FreeBSD compatibility code.  Remove support for versions of
  94      Linux before 2.6.  Start using Linux facilities.
  95
  96This README file addresses the Linux version of the driver. Under FreeBSD, 
  97the driver documentation is the sym.8 man page.
  98
  99Information about new chips is available at LSILOGIC web server:
 100
 101          http://www.lsilogic.com/
 102
 103SCSI standard documentations are available at T10 site:
 104
 105          http://www.t10.org/
 106
 107Useful SCSI tools written by Eric Youngdale are part of most Linux 
 108distributions:
 109   scsiinfo:    command line tool
 110   scsi-config: TCL/Tk tool using scsiinfo
 111
 1122. Supported chips and SCSI features
 113
 114The following features are supported for all chips:
 115
 116        Synchronous negotiation
 117        Disconnection
 118        Tagged command queuing
 119        SCSI parity checking
 120        PCI Master parity checking
 121
 122Other features depends on chip capabilities.
 123The driver notably uses optimized SCRIPTS for devices that support 
 124LOAD/STORE and handles PHASE MISMATCH from SCRIPTS for devices that 
 125support the corresponding feature.
 126
 127The following table shows some characteristics of the chip family.
 128
 129       On board                                   LOAD/STORE   HARDWARE
 130Chip   SDMS BIOS   Wide   SCSI std.   Max. sync   SCRIPTS      PHASE MISMATCH
 131----   ---------   ----   ---------   ----------  ----------   --------------
 132810        N         N      FAST10    10 MB/s        N             N
 133810A       N         N      FAST10    10 MB/s        Y             N
 134815        Y         N      FAST10    10 MB/s        N             N
 135825        Y         Y      FAST10    20 MB/s        N             N
 136825A       Y         Y      FAST10    20 MB/s        Y             N
 137860        N         N      FAST20    20 MB/s        Y             N
 138875        Y         Y      FAST20    40 MB/s        Y             N
 139875A       Y         Y      FAST20    40 MB/s        Y             Y
 140876        Y         Y      FAST20    40 MB/s        Y             N
 141895        Y         Y      FAST40    80 MB/s        Y             N
 142895A       Y         Y      FAST40    80 MB/s        Y             Y
 143896        Y         Y      FAST40    80 MB/s        Y             Y
 144897        Y         Y      FAST40    80 MB/s        Y             Y
 1451510D      Y         Y      FAST40    80 MB/s        Y             Y
 1461010       Y         Y      FAST80   160 MB/s        Y             Y
 1471010_66*   Y         Y      FAST80   160 MB/s        Y             Y
 148
 149* Chip supports 33MHz and 66MHz PCI bus clock.
 150
 151
 152Summary of other supported features:
 153
 154Module:                allow to load the driver
 155Memory mapped I/O:     increases performance
 156Control commands:      write operations to the proc SCSI file system
 157Debugging information: written to syslog (expert only)
 158Scatter / gather
 159Shared interrupt
 160Boot setup commands
 161Serial NVRAM:          Symbios and Tekram formats
 162
 163
 1643. Advantages of this driver for newer chips.
 165
 1663.1 Optimized SCSI SCRIPTS.
 167
 168All chips except the 810, 815 and 825, support new SCSI SCRIPTS instructions 
 169named LOAD and STORE that allow to move up to 1 DWORD from/to an IO register 
 170to/from memory much faster that the MOVE MEMORY instruction that is supported 
 171by the 53c7xx and 53c8xx family.
 172
 173The LOAD/STORE instructions support absolute and DSA relative addressing 
 174modes. The SCSI SCRIPTS had been entirely rewritten using LOAD/STORE instead 
 175of MOVE MEMORY instructions.
 176
 177Due to the lack of LOAD/STORE SCRIPTS instructions by earlier chips, this 
 178driver also incorporates a different SCRIPTS set based on MEMORY MOVE, in 
 179order to provide support for the entire SYM53C8XX chips family.
 180
 1813.2 New features appeared with the SYM53C896
 182
 183Newer chips (see above) allows handling of the phase mismatch context from 
 184SCRIPTS (avoids the phase mismatch interrupt that stops the SCSI processor 
 185until the C code has saved the context of the transfer).
 186
 187The 896 and 1010 chips support 64 bit PCI transactions and addressing, 
 188while the 895A supports 32 bit PCI transactions and 64 bit addressing.
 189The SCRIPTS processor of these chips is not true 64 bit, but uses segment 
 190registers for bit 32-63. Another interesting feature is that LOAD/STORE 
 191instructions that address the on-chip RAM (8k) remain internal to the chip.
 192
 1934. Memory mapped I/O versus normal I/O
 194
 195Memory mapped I/O has less latency than normal I/O and is the recommended 
 196way for doing IO with PCI devices. Memory mapped I/O seems to work fine on 
 197most hardware configurations, but some poorly designed chipsets may break 
 198this feature. A configuration option is provided for normal I/O to be 
 199used but the driver defaults to MMIO.
 200
 2015. Tagged command queueing
 202
 203Queuing more than 1 command at a time to a device allows it to perform 
 204optimizations based on actual head positions and its mechanical 
 205characteristics. This feature may also reduce average command latency.
 206In order to really gain advantage of this feature, devices must have 
 207a reasonable cache size (No miracle is to be expected for a low-end 
 208hard disk with 128 KB or less).
 209Some known old SCSI devices do not properly support tagged command queuing.
 210Generally, firmware revisions that fix this kind of problems are available 
 211at respective vendor web/ftp sites.
 212All I can say is that I never have had problem with tagged queuing using 
 213this driver and its predecessors. Hard disks that behaved correctly for 
 214me using tagged commands are the following:
 215
 216- IBM S12 0662
 217- Conner 1080S
 218- Quantum Atlas I
 219- Quantum Atlas II
 220- Seagate Cheetah I
 221- Quantum Viking II
 222- IBM DRVS
 223- Quantum Atlas IV
 224- Seagate Cheetah II
 225
 226If your controller has NVRAM, you can configure this feature per target 
 227from the user setup tool. The Tekram Setup program allows to tune the 
 228maximum number of queued commands up to 32. The Symbios Setup only allows 
 229to enable or disable this feature.
 230
 231The maximum number of simultaneous tagged commands queued to a device
 232is currently set to 16 by default.  This value is suitable for most SCSI
 233disks.  With large SCSI disks (>= 2GB, cache >= 512KB, average seek time
 234<= 10 ms), using a larger value may give better performances.
 235
 236This driver supports up to 255 commands per device, and but using more than 
 23764 is generally not worth-while, unless you are using a very large disk or 
 238disk arrays. It is noticeable that most of recent hard disks seem not to 
 239accept more than 64 simultaneous commands. So, using more than 64 queued 
 240commands is probably just resource wasting.
 241
 242If your controller does not have NVRAM or if it is managed by the SDMS 
 243BIOS/SETUP, you can configure tagged queueing feature and device queue 
 244depths from the boot command-line. For example:
 245
 246  sym53c8xx=tags:4/t2t3q15-t4q7/t1u0q32
 247
 248will set tagged commands queue depths as follow:
 249
 250- target 2  all luns  on controller 0 --> 15
 251- target 3  all luns  on controller 0 --> 15
 252- target 4  all luns  on controller 0 -->  7
 253- target 1  lun 0     on controller 1 --> 32
 254- all other target/lun                -->  4
 255
 256In some special conditions, some SCSI disk firmwares may return a
 257QUEUE FULL status for a SCSI command. This behaviour is managed by the
 258driver using the following heuristic:
 259
 260- Each time a QUEUE FULL status is returned, tagged queue depth is reduced 
 261  to the actual number of disconnected commands. 
 262
 263- Every 200 successfully completed SCSI commands, if allowed by the
 264  current limit, the maximum number of queueable commands is incremented.
 265
 266Since QUEUE FULL status reception and handling is resource wasting, the 
 267driver notifies by default this problem to user by indicating the actual 
 268number of commands used and their status, as well as its decision on the 
 269device queue depth change.
 270The heuristic used by the driver in handling QUEUE FULL ensures that the 
 271impact on performances is not too bad. You can get rid of the messages by 
 272setting verbose level to zero, as follow:
 273
 2741st method: boot your system using 'sym53c8xx=verb:0' option.
 2752nd method: apply "setverbose 0" control command to the proc fs entry 
 276            corresponding to your controller after boot-up.
 277
 2786. Parity checking
 279
 280The driver supports SCSI parity checking and PCI bus master parity
 281checking.  These features must be enabled in order to ensure safe
 282data transfers.  Some flawed devices or mother boards may have problems
 283with parity.  The options to defeat parity checking have been removed
 284from the driver.
 285
 2867. Profiling information
 287
 288This driver does not provide profiling information as did its predecessors.
 289This feature was not this useful and added complexity to the code. 
 290As the driver code got more complex, I have decided to remove everything 
 291that didn't seem actually useful.
 292
 2938. Control commands
 294
 295Control commands can be sent to the driver with write operations to
 296the proc SCSI file system. The generic command syntax is the
 297following:
 298
 299      echo "<verb> <parameters>" >/proc/scsi/sym53c8xx/0
 300      (assumes controller number is 0)
 301
 302Using "all" for "<target>" parameter with the commands below will
 303apply to all targets of the SCSI chain (except the controller).
 304
 305Available commands:
 306
 3078.1 Set minimum synchronous period factor
 308
 309    setsync <target> <period factor>
 310
 311    target:    target number
 312    period:    minimum synchronous period.
 313               Maximum speed = 1000/(4*period factor) except for special
 314               cases below.
 315
 316    Specify a period of 0, to force asynchronous transfer mode.
 317
 318       9 means 12.5 nano-seconds synchronous period
 319      10 means 25 nano-seconds synchronous period
 320      11 means 30 nano-seconds synchronous period
 321      12 means 50 nano-seconds synchronous period
 322
 3238.2 Set wide size
 324
 325    setwide <target> <size>
 326
 327    target:    target number
 328    size:      0=8 bits, 1=16bits
 329
 3308.3 Set maximum number of concurrent tagged commands
 331 
 332    settags <target> <tags>
 333
 334    target:    target number
 335    tags:      number of concurrent tagged commands
 336               must not be greater than configured (default: 16)
 337
 3388.4 Set debug mode
 339
 340    setdebug <list of debug flags>
 341
 342    Available debug flags:
 343        alloc:   print info about memory allocations (ccb, lcb)
 344        queue:   print info about insertions into the command start queue
 345        result:  print sense data on CHECK CONDITION status
 346        scatter: print info about the scatter process
 347        scripts: print info about the script binding process
 348        tiny:    print minimal debugging information
 349        timing:  print timing information of the NCR chip
 350        nego:    print information about SCSI negotiations
 351        phase:   print information on script interruptions
 352
 353    Use "setdebug" with no argument to reset debug flags.
 354
 355
 3568.5 Set flag (no_disc)
 357 
 358    setflag <target> <flag>
 359
 360    target:    target number
 361
 362    For the moment, only one flag is available:
 363
 364        no_disc:   not allow target to disconnect.
 365
 366    Do not specify any flag in order to reset the flag. For example:
 367    - setflag 4
 368      will reset no_disc flag for target 4, so will allow it disconnections.
 369    - setflag all
 370      will allow disconnection for all devices on the SCSI bus.
 371
 372
 3738.6 Set verbose level
 374
 375    setverbose #level
 376
 377    The driver default verbose level is 1. This command allows to change 
 378    th driver verbose level after boot-up.
 379
 3808.7 Reset all logical units of a target
 381
 382    resetdev <target>
 383
 384    target:    target number
 385    The driver will try to send a BUS DEVICE RESET message to the target.
 386
 3878.8 Abort all tasks of all logical units of a target
 388
 389    cleardev <target>
 390
 391    target:    target number
 392    The driver will try to send a ABORT message to all the logical units 
 393    of the target.
 394
 395
 3969. Configuration parameters
 397
 398Under kernel configuration tools (make menuconfig, for example), it is 
 399possible to change some default driver configuration parameters.
 400If the firmware of all your devices is perfect enough, all the
 401features supported by the driver can be enabled at start-up. However,
 402if only one has a flaw for some SCSI feature, you can disable the
 403support by the driver of this feature at linux start-up and enable
 404this feature after boot-up only for devices that support it safely.
 405
 406Configuration parameters:
 407
 408Use normal IO                         (default answer: n)
 409    Answer "y" if you suspect your mother board to not allow memory mapped I/O.
 410    May slow down performance a little.
 411
 412Default tagged command queue depth    (default answer: 16)
 413    Entering 0 defaults to tagged commands not being used.
 414    This parameter can be specified from the boot command line.
 415
 416Maximum number of queued commands     (default answer: 32)
 417    This option allows you to specify the maximum number of tagged commands 
 418    that can be queued to a device. The maximum supported value is 255.
 419
 420Synchronous transfers frequency       (default answer: 80)
 421    This option allows you to specify the frequency in MHz the driver 
 422    will use at boot time for synchronous data transfer negotiations.
 423    0 means "asynchronous data transfers".
 424
 42510. Boot setup commands
 426
 42710.1 Syntax
 428
 429Setup commands can be passed to the driver either at boot time or as
 430parameters to modprobe, as described in Documentation/kernel-parameters.txt
 431
 432Example of boot setup command under lilo prompt:
 433
 434lilo: linux root=/dev/sda2 sym53c8xx.cmd_per_lun=4 sym53c8xx.sync=10 sym53c8xx.debug=0x200
 435
 436- enable tagged commands, up to 4 tagged commands queued.
 437- set synchronous negotiation speed to 10 Mega-transfers / second.
 438- set DEBUG_NEGO flag.
 439
 440The following command will install the driver module with the same
 441options as above.
 442
 443    modprobe sym53c8xx cmd_per_lun=4 sync=10 debug=0x200
 444
 44510.2 Available arguments
 446
 44710.2.1  Default number of tagged commands
 448        cmd_per_lun=0 (or cmd_per_lun=1) tagged command queuing disabled
 449        cmd_per_lun=#tags (#tags > 1) tagged command queuing enabled
 450  #tags will be truncated to the max queued commands configuration parameter.
 451
 45210.2.2 Burst max
 453        burst=0    burst disabled
 454        burst=255  get burst length from initial IO register settings.
 455        burst=#x   burst enabled (1<<#x burst transfers max)
 456  #x is an integer value which is log base 2 of the burst transfers max.
 457  By default the driver uses the maximum value supported by the chip.
 458
 45910.2.3 LED support
 460        led=1      enable  LED support
 461        led=0      disable LED support
 462  Do not enable LED support if your scsi board does not use SDMS BIOS.
 463  (See 'Configuration parameters')
 464
 46510.2.4 Differential mode
 466        diff=0  never set up diff mode
 467        diff=1  set up diff mode if BIOS set it
 468        diff=2  always set up diff mode
 469        diff=3  set diff mode if GPIO3 is not set
 470
 47110.2.5 IRQ mode
 472        irqm=0     always open drain
 473        irqm=1     same as initial settings (assumed BIOS settings)
 474        irqm=2     always totem pole
 475
 47610.2.6 Check SCSI BUS 
 477        buschk=<option bits>
 478
 479    Available option bits:
 480        0x0:   No check.
 481        0x1:   Check and do not attach the controller on error.  
 482        0x2:   Check and just warn on error.
 483
 48410.2.7 Suggest a default SCSI id for hosts
 485        hostid=255      no id suggested.
 486        hostid=#x   (0 < x < 7) x suggested for hosts SCSI id.
 487
 488    If a host SCSI id is available from the NVRAM, the driver will ignore 
 489    any value suggested as boot option. Otherwise, if a suggested value 
 490    different from 255 has been supplied, it will use it. Otherwise, it will 
 491    try to deduce the value previously set in the hardware and use value 
 492    7 if the hardware value is zero.
 493
 49410.2.8  Verbosity level
 495        verb=0     minimal
 496        verb=1     normal
 497        verb=2     too much
 498
 49910.2.9 Debug mode
 500        debug=0  clear debug flags
 501        debug=#x   set debug flags
 502  #x is an integer value combining the following power-of-2 values:
 503  DEBUG_ALLOC       0x1
 504  DEBUG_PHASE       0x2
 505  DEBUG_POLL        0x4
 506  DEBUG_QUEUE       0x8
 507  DEBUG_RESULT     0x10
 508  DEBUG_SCATTER    0x20
 509  DEBUG_SCRIPT     0x40
 510  DEBUG_TINY       0x80
 511  DEBUG_TIMING    0x100
 512  DEBUG_NEGO      0x200
 513  DEBUG_TAGS      0x400
 514  DEBUG_FREEZE    0x800
 515  DEBUG_RESTART  0x1000
 516
 517  You can play safely with DEBUG_NEGO. However, some of these flags may 
 518  generate bunches of syslog messages. 
 519
 52010.2.10 Settle delay
 521        settle=n        delay for n seconds
 522
 523  After a bus reset, the driver will delay for n seconds before talking
 524  to any device on the bus.  The default is 3 seconds and safe mode will
 525  default it to 10.
 526
 52710.2.11 Serial NVRAM
 528        NB: option not currently implemented.
 529        nvram=n     do not look for serial NVRAM
 530        nvram=y     test controllers for onboard serial NVRAM
 531        (alternate binary form)
 532        nvram=<bits options>
 533        0x01   look for NVRAM  (equivalent to nvram=y)
 534        0x02   ignore NVRAM "Synchronous negotiation" parameters for all devices
 535        0x04   ignore NVRAM "Wide negotiation"  parameter for all devices
 536        0x08   ignore NVRAM "Scan at boot time" parameter for all devices
 537        0x80   also attach controllers set to OFF in the NVRAM (sym53c8xx only)
 538
 53910.2.12 Exclude a host from being attached
 540        excl=<io_address>,...
 541
 542    Prevent host at a given io address from being attached.
 543    For example 'excl=0xb400,0xc000' indicate to the 
 544    driver not to attach hosts at address 0xb400 and 0xc000.
 545
 54610.3 Converting from old style options
 547
 548Previously, the sym2 driver accepted arguments of the form
 549        sym53c8xx=tags:4,sync:10,debug:0x200
 550
 551As a result of the new module parameters, this is no longer available.
 552Most of the options have remained the same, but tags has become
 553cmd_per_lun to reflect its different purposes.  The sample above would
 554be specified as:
 555        modprobe sym53c8xx cmd_per_lun=4 sync=10 debug=0x200
 556
 557or on the kernel boot line as:
 558        sym53c8xx.cmd_per_lun=4 sym53c8xx.sync=10 sym53c8xx.debug=0x200
 559
 56010.4 SCSI BUS checking boot option.
 561
 562When this option is set to a non-zero value, the driver checks SCSI lines 
 563logic state, 100 micro-seconds after having asserted the SCSI RESET line.
 564The driver just reads SCSI lines and checks all lines read FALSE except RESET.
 565Since SCSI devices shall release the BUS at most 800 nano-seconds after SCSI 
 566RESET has been asserted, any signal to TRUE may indicate a SCSI BUS problem.
 567Unfortunately, the following common SCSI BUS problems are not detected:
 568- Only 1 terminator installed.
 569- Misplaced terminators.
 570- Bad quality terminators.
 571On the other hand, either bad cabling, broken devices, not conformant 
 572devices, ... may cause a SCSI signal to be wrong when te driver reads it.
 573
 57415. SCSI problem troubleshooting
 575
 57615.1 Problem tracking
 577
 578Most SCSI problems are due to a non conformant SCSI bus or too buggy
 579devices.  If unfortunately you have SCSI problems, you can check the
 580following things:
 581
 582- SCSI bus cables
 583- terminations at both end of the SCSI chain
 584- linux syslog messages (some of them may help you)
 585
 586If you do not find the source of problems, you can configure the
 587driver or devices in the NVRAM with minimal features.
 588
 589- only asynchronous data transfers
 590- tagged commands disabled
 591- disconnections not allowed
 592
 593Now, if your SCSI bus is ok, your system has every chance to work
 594with this safe configuration but performances will not be optimal.
 595
 596If it still fails, then you can send your problem description to
 597appropriate mailing lists or news-groups.  Send me a copy in order to
 598be sure I will receive it.  Obviously, a bug in the driver code is
 599possible.
 600
 601  My current email address: Gerard Roudier <groudier@free.fr>
 602
 603Allowing disconnections is important if you use several devices on
 604your SCSI bus but often causes problems with buggy devices.
 605Synchronous data transfers increases throughput of fast devices like
 606hard disks.  Good SCSI hard disks with a large cache gain advantage of
 607tagged commands queuing.
 608
 60915.2 Understanding hardware error reports
 610
 611When the driver detects an unexpected error condition, it may display a 
 612message of the following pattern.
 613
 614sym0:1: ERROR (0:48) (1-21-65) (f/95/0) @ (script 7c0:19000000).
 615sym0: script cmd = 19000000
 616sym0: regdump: da 10 80 95 47 0f 01 07 75 01 81 21 80 01 09 00.
 617
 618Some fields in such a message may help you understand the cause of the 
 619problem, as follows:
 620
 621sym0:1: ERROR (0:48) (1-21-65) (f/95/0) @ (script 7c0:19000000).
 622.....A.........B.C....D.E..F....G.H..I.......J.....K...L.......
 623
 624Field A : target number.
 625  SCSI ID of the device the controller was talking with at the moment the 
 626  error occurs.
 627
 628Field B : DSTAT io register (DMA STATUS)
 629  Bit 0x40 : MDPE Master Data Parity Error
 630             Data parity error detected on the PCI BUS.
 631  Bit 0x20 : BF   Bus Fault
 632             PCI bus fault condition detected
 633  Bit 0x01 : IID  Illegal Instruction Detected
 634             Set by the chip when it detects an Illegal Instruction format 
 635             on some condition that makes an instruction illegal.
 636  Bit 0x80 : DFE Dma Fifo Empty
 637             Pure status bit that does not indicate an error.
 638  If the reported DSTAT value contains a combination of MDPE (0x40), 
 639  BF (0x20), then the cause may be likely due to a PCI BUS problem.
 640
 641Field C : SIST io register (SCSI Interrupt Status)
 642  Bit 0x08 : SGE  SCSI GROSS ERROR
 643             Indicates that the chip detected a severe error condition 
 644             on the SCSI BUS that prevents the SCSI protocol from functioning
 645             properly.
 646  Bit 0x04 : UDC  Unexpected Disconnection
 647             Indicates that the device released the SCSI BUS when the chip 
 648             was not expecting this to happen. A device may behave so to 
 649             indicate the SCSI initiator that an error condition not reportable              using the SCSI protocol has occurred.
 650  Bit 0x02 : RST  SCSI BUS Reset
 651             Generally SCSI targets do not reset the SCSI BUS, although any 
 652             device on the BUS can reset it at any time.
 653  Bit 0x01 : PAR  Parity
 654             SCSI parity error detected.
 655  On a faulty SCSI BUS, any error condition among SGE (0x08), UDC (0x04) and 
 656  PAR (0x01) may be detected by the chip. If your SCSI system sometimes 
 657  encounters such error conditions, especially SCSI GROSS ERROR, then a SCSI 
 658  BUS problem is likely the cause of these errors.
 659
 660For fields D,E,F,G and H, you may look into the sym53c8xx_defs.h file 
 661that contains some minimal comments on IO register bits.
 662Field D : SOCL  Scsi Output Control Latch
 663          This register reflects the state of the SCSI control lines the 
 664          chip want to drive or compare against.
 665Field E : SBCL  Scsi Bus Control Lines
 666          Actual value of control lines on the SCSI BUS.
 667Field F : SBDL  Scsi Bus Data Lines
 668          Actual value of data lines on the SCSI BUS.
 669Field G : SXFER  SCSI Transfer
 670          Contains the setting of the Synchronous Period for output and 
 671          the current Synchronous offset (offset 0 means asynchronous).
 672Field H : SCNTL3 Scsi Control Register 3
 673          Contains the setting of timing values for both asynchronous and 
 674          synchronous data transfers. 
 675Field I : SCNTL4 Scsi Control Register 4
 676          Only meaningful for 53C1010 Ultra3 controllers.
 677
 678Understanding Fields J, K, L and dumps requires to have good knowledge of 
 679SCSI standards, chip cores functionnals and internal driver data structures.
 680You are not required to decode and understand them, unless you want to help 
 681maintain the driver code.
 682
 68317. Serial NVRAM (added by Richard Waltham: dormouse@farsrobt.demon.co.uk)
 684
 68517.1 Features
 686
 687Enabling serial NVRAM support enables detection of the serial NVRAM included
 688on Symbios and some Symbios compatible host adaptors, and Tekram boards. The 
 689serial NVRAM is used by Symbios and Tekram to hold set up parameters for the 
 690host adaptor and its attached drives.
 691
 692The Symbios NVRAM also holds data on the boot order of host adaptors in a
 693system with more than one host adaptor.  This information is no longer used
 694as it's fundamentally incompatible with the hotplug PCI model.
 695
 696Tekram boards using Symbios chips, DC390W/F/U, which have NVRAM are detected
 697and this is used to distinguish between Symbios compatible and Tekram host 
 698adaptors. This is used to disable the Symbios compatible "diff" setting
 699incorrectly set on Tekram boards if the CONFIG_SCSI_53C8XX_SYMBIOS_COMPAT 
 700configuration parameter is set enabling both Symbios and Tekram boards to be 
 701used together with the Symbios cards using all their features, including
 702"diff" support. ("led pin" support for Symbios compatible cards can remain
 703enabled when using Tekram cards. It does nothing useful for Tekram host
 704adaptors but does not cause problems either.)
 705
 706The parameters the driver is able to get from the NVRAM depend on the 
 707data format used, as follow:
 708
 709                                 Tekram format      Symbios format
 710General and host parameters
 711    Boot order                         N                   Y
 712    Host SCSI ID                       Y                   Y
 713    SCSI parity checking               Y                   Y
 714    Verbose boot messages              N                   Y
 715SCSI devices parameters
 716    Synchronous transfer speed         Y                   Y
 717    Wide 16 / Narrow                   Y                   Y
 718    Tagged Command Queuing enabled     Y                   Y
 719    Disconnections enabled             Y                   Y
 720    Scan at boot time                  N                   Y
 721
 722In order to speed up the system boot, for each device configured without 
 723the "scan at boot time" option, the driver forces an error on the 
 724first TEST UNIT READY command received for this device.
 725
 726
 72717.2 Symbios NVRAM layout
 728
 729typical data at NVRAM address 0x100 (53c810a NVRAM)
 730-----------------------------------------------------------
 73100 00
 73264 01
 7338e 0b
 734
 73500 30 00 00 00 00 07 00 00 00 00 00 00 00 07 04 10 04 00 00 
 736
 73704 00 0f 00 00 10 00 50 00 00 01 00 00 62 
 73804 00 03 00 00 10 00 58 00 00 01 00 00 63 
 73904 00 01 00 00 10 00 48 00 00 01 00 00 61 
 74000 00 00 00 00 00 00 00 00 00 00 00 00 00 
 741
 7420f 00 08 08 64 00 0a 00
 7430f 00 08 08 64 00 0a 00 
 7440f 00 08 08 64 00 0a 00 
 7450f 00 08 08 64 00 0a 00 
 7460f 00 08 08 64 00 0a 00 
 7470f 00 08 08 64 00 0a 00 
 7480f 00 08 08 64 00 0a 00 
 7490f 00 08 08 64 00 0a 00 
 750
 7510f 00 08 08 64 00 0a 00 
 7520f 00 08 08 64 00 0a 00 
 7530f 00 08 08 64 00 0a 00 
 7540f 00 08 08 64 00 0a 00 
 7550f 00 08 08 64 00 0a 00 
 7560f 00 08 08 64 00 0a 00 
 7570f 00 08 08 64 00 0a 00 
 7580f 00 08 08 64 00 0a 00 
 759
 76000 00 00 00 00 00 00 00 
 76100 00 00 00 00 00 00 00 
 76200 00 00 00 00 00 00 00 
 76300 00 00 00 00 00 00 00 
 76400 00 00 00 00 00 00 00 
 76500 00 00 00 00 00 00 00 
 76600 00 00 00 00 00 00 00 
 76700 00 00 00 00 00 00 00 
 768
 76900 00 00 00 00 00 00 00 
 77000 00 00 00 00 00 00 00 
 77100 00 00 00 00 00 00 00 
 77200 00 00 00 00 00 00 00 
 77300 00 00 00 00 00 00 00 
 77400 00 00 00 00 00 00 00 
 77500 00 00 00 00 00 00 00 
 77600 00 00 00 00 00 00 00 
 777
 77800 00 00 00 00 00 00 00 
 77900 00 00 00 00 00 00 00 
 78000 00 00 00 00 00 00 00 
 781
 782fe fe
 78300 00
 78400 00
 785-----------------------------------------------------------
 786NVRAM layout details
 787
 788NVRAM Address 0x000-0x0ff not used
 789              0x100-0x26f initialised data
 790              0x270-0x7ff not used
 791
 792general layout
 793
 794        header  -   6 bytes,
 795        data    - 356 bytes (checksum is byte sum of this data)
 796        trailer -   6 bytes
 797                  ---
 798        total     368 bytes
 799
 800data area layout
 801
 802        controller set up  -  20 bytes
 803        boot configuration -  56 bytes (4x14 bytes)
 804        device set up      - 128 bytes (16x8 bytes)
 805        unused (spare?)    - 152 bytes (19x8 bytes)
 806                             ---
 807        total                356 bytes
 808
 809-----------------------------------------------------------
 810header
 811
 81200 00   - ?? start marker
 81364 01   - byte count (lsb/msb excludes header/trailer)
 8148e 0b   - checksum (lsb/msb excludes header/trailer)
 815-----------------------------------------------------------
 816controller set up
 817
 81800 30 00 00 00 00 07 00 00 00 00 00 00 00 07 04 10 04 00 00
 819                   |     |           |     |
 820                   |     |           |      -- host ID
 821                   |     |           |
 822                   |     |            --Removable Media Support
 823                   |     |               0x00 = none
 824                   |     |               0x01 = Bootable Device
 825                   |     |               0x02 = All with Media
 826                   |     |
 827                   |      --flag bits 2
 828                   |        0x00000001= scan order hi->low
 829                   |            (default 0x00 - scan low->hi)
 830                    --flag bits 1
 831                       0x00000001 scam enable
 832                       0x00000010 parity enable
 833                       0x00000100 verbose boot msgs
 834
 835remaining bytes unknown - they do not appear to change in my
 836current set up for any of the controllers.
 837
 838default set up is identical for 53c810a and 53c875 NVRAM
 839(Removable Media added Symbios BIOS version 4.09)
 840-----------------------------------------------------------
 841boot configuration
 842
 843boot order set by order of the devices in this table
 844
 84504 00 0f 00 00 10 00 50 00 00 01 00 00 62 -- 1st controller
 84604 00 03 00 00 10 00 58 00 00 01 00 00 63    2nd controller
 84704 00 01 00 00 10 00 48 00 00 01 00 00 61    3rd controller
 84800 00 00 00 00 00 00 00 00 00 00 00 00 00    4th controller
 849       |  |  |  |     |        |     |  |
 850       |  |  |  |     |        |      ---- PCI io port adr
 851       |  |  |  |     |         --0x01 init/scan at boot time
 852       |  |  |  |      --PCI device/function number (0xdddddfff)
 853       |  |   ----- ?? PCI vendor ID (lsb/msb)
 854        ----PCI device ID (lsb/msb)
 855
 856?? use of this data is a guess but seems reasonable
 857
 858remaining bytes unknown - they do not appear to change in my
 859current set up
 860
 861default set up is identical for 53c810a and 53c875 NVRAM
 862-----------------------------------------------------------
 863device set up (up to 16 devices - includes controller)
 864
 8650f 00 08 08 64 00 0a 00 - id 0
 8660f 00 08 08 64 00 0a 00 
 8670f 00 08 08 64 00 0a 00 
 8680f 00 08 08 64 00 0a 00 
 8690f 00 08 08 64 00 0a 00 
 8700f 00 08 08 64 00 0a 00 
 8710f 00 08 08 64 00 0a 00 
 8720f 00 08 08 64 00 0a 00 
 873
 8740f 00 08 08 64 00 0a 00 
 8750f 00 08 08 64 00 0a 00 
 8760f 00 08 08 64 00 0a 00 
 8770f 00 08 08 64 00 0a 00 
 8780f 00 08 08 64 00 0a 00 
 8790f 00 08 08 64 00 0a 00 
 8800f 00 08 08 64 00 0a 00 
 8810f 00 08 08 64 00 0a 00 - id 15
 882 |     |  |  |     |  |
 883 |     |  |  |      ----timeout (lsb/msb)
 884 |     |  |   --synch period (0x?? 40 Mtrans/sec- fast 40) (probably 0x28)
 885 |     |  |                  (0x30 20 Mtrans/sec- fast 20)
 886 |     |  |                  (0x64 10 Mtrans/sec- fast )
 887 |     |  |                  (0xc8  5 Mtrans/sec)
 888 |     |  |                  (0x00  asynchronous)
 889 |     |   -- ?? max sync offset (0x08 in NVRAM on 53c810a) 
 890 |     |                         (0x10 in NVRAM on 53c875)
 891 |      --device bus width (0x08 narrow)
 892 |                         (0x10 16 bit wide)
 893  --flag bits
 894    0x00000001 - disconnect enabled
 895    0x00000010 - scan at boot time
 896    0x00000100 - scan luns
 897    0x00001000 - queue tags enabled
 898
 899remaining bytes unknown - they do not appear to change in my
 900current set up
 901
 902?? use of this data is a guess but seems reasonable 
 903(but it could be max bus width)
 904
 905default set up for 53c810a NVRAM
 906default set up for 53c875 NVRAM - bus width     - 0x10
 907                                - sync offset ? - 0x10
 908                                - sync period   - 0x30
 909-----------------------------------------------------------
 910?? spare device space (32 bit bus ??)
 911
 91200 00 00 00 00 00 00 00  (19x8bytes)
 913.
 914.
 91500 00 00 00 00 00 00 00
 916
 917default set up is identical for 53c810a and 53c875 NVRAM
 918-----------------------------------------------------------
 919trailer
 920
 921fe fe   - ? end marker ?
 92200 00
 92300 00
 924
 925default set up is identical for 53c810a and 53c875 NVRAM
 926-----------------------------------------------------------
 927
 928
 929
 93017.3 Tekram NVRAM layout
 931
 932nvram 64x16 (1024 bit)
 933
 934Drive settings
 935
 936Drive ID 0-15 (addr 0x0yyyy0 = device setup, yyyy = ID)
 937              (addr 0x0yyyy1 = 0x0000)
 938
 939    x x x x  x x x x  x x x x  x x x x
 940               | | |      | |  | | | |
 941               | | |      | |  | | |  ----- parity check   0 - off
 942               | | |      | |  | | |                       1 - on
 943               | | |      | |  | | |
 944               | | |      | |  | |  ------- sync neg       0 - off
 945               | | |      | |  | |                         1 - on
 946               | | |      | |  | |
 947               | | |      | |  |  --------- disconnect     0 - off
 948               | | |      | |  |                           1 - on
 949               | | |      | |  |
 950               | | |      | |   ----------- start cmd      0 - off
 951               | | |      | |                              1 - on
 952               | | |      | |
 953               | | |      |  -------------- tagged cmds    0 - off
 954               | | |      |                                1 - on
 955               | | |      | 
 956               | | |       ---------------- wide neg       0 - off
 957               | | |                                       1 - on
 958               | | |
 959                --------------------------- sync rate      0 - 10.0 Mtrans/sec
 960                                                           1 -  8.0
 961                                                           2 -  6.6
 962                                                           3 -  5.7
 963                                                           4 -  5.0
 964                                                           5 -  4.0
 965                                                           6 -  3.0
 966                                                           7 -  2.0
 967                                                           7 -  2.0
 968                                                           8 - 20.0
 969                                                           9 - 16.7
 970                                                           a - 13.9
 971                                                           b - 11.9
 972
 973Global settings
 974
 975Host flags 0 (addr 0x100000, 32) 
 976
 977    x x x x  x x x x  x x x x  x x x x
 978    | | | |  | | | |           | | | |
 979    | | | |  | | | |            ----------- host ID    0x00 - 0x0f
 980    | | | |  | | | |
 981    | | | |  | | |  ----------------------- support for    0 - off
 982    | | | |  | | |                          > 2 drives     1 - on
 983    | | | |  | | | 
 984    | | | |  | |  ------------------------- support drives 0 - off
 985    | | | |  | |                            > 1Gbytes      1 - on
 986    | | | |  | |
 987    | | | |  |  --------------------------- bus reset on   0 - off
 988    | | | |  |                                power on     1 - on
 989    | | | |  |
 990    | | | |   ----------------------------- active neg     0 - off
 991    | | | |                                                1 - on
 992    | | | |
 993    | | |  -------------------------------- imm seek       0 - off
 994    | | |                                                  1 - on
 995    | | |
 996    | |  ---------------------------------- scan luns      0 - off
 997    | |                                                    1 - on
 998    | |
 999     -------------------------------------- removable      0 - disable
1000                                            as BIOS dev    1 - boot device
1001                                                           2 - all
1002
1003Host flags 1 (addr 0x100001, 33)
1004
1005    x x x x  x x x x  x x x x  x x x x
1006               | | |             | | | 
1007               | | |              --------- boot delay     0 -   3 sec
1008               | | |                                       1 -   5
1009               | | |                                       2 -  10
1010               | | |                                       3 -  20
1011               | | |                                       4 -  30
1012               | | |                                       5 -  60
1013               | | |                                       6 - 120
1014               | | |
1015                --------------------------- max tag cmds   0 -  2
1016                                                           1 -  4
1017                                                           2 -  8
1018                                                           3 - 16
1019                                                           4 - 32
1020
1021Host flags 2 (addr 0x100010, 34)
1022
1023    x x x x  x x x x  x x x x  x x x x
1024                                     |
1025                                      ----- F2/F6 enable   0 - off ???
1026                                                           1 - on  ???
1027
1028checksum (addr 0x111111)
1029
1030checksum = 0x1234 - (sum addr 0-63)
1031
1032----------------------------------------------------------------------------
1033
1034default nvram data:
1035
10360x0037 0x0000 0x0037 0x0000 0x0037 0x0000 0x0037 0x0000
10370x0037 0x0000 0x0037 0x0000 0x0037 0x0000 0x0037 0x0000
10380x0037 0x0000 0x0037 0x0000 0x0037 0x0000 0x0037 0x0000
10390x0037 0x0000 0x0037 0x0000 0x0037 0x0000 0x0037 0x0000 
1040
10410x0f07 0x0400 0x0001 0x0000 0x0000 0x0000 0x0000 0x0000
10420x0000 0x0000 0x0000 0x0000 0x0000 0x0000 0x0000 0x0000
10430x0000 0x0000 0x0000 0x0000 0x0000 0x0000 0x0000 0x0000
10440x0000 0x0000 0x0000 0x0000 0x0000 0x0000 0x0000 0xfbbc
1045
1046
1047===============================================================================
1048End of Linux SYM-2 driver documentation file
1049
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