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+The Linux NCR53C8XX/SYM53C8XX drivers README file
+
+Written by Gerard Roudier <groudier@free.fr>
+21 Rue Carnot
+95170 DEUIL LA BARRE - FRANCE
+
+29 May 1999
+===============================================================================
+
+1.  Introduction
+2.  Supported chips and SCSI features
+3.  Advantages of the enhanced 896 driver
+      3.1 Optimized SCSI SCRIPTS
+      3.2 New features of the SYM53C896 (64 bit PCI dual LVD SCSI controller)
+4.  Memory mapped I/O versus normal I/O
+5.  Tagged command queueing
+6.  Parity checking
+7.  Profiling information
+8.  Control commands
+      8.1  Set minimum synchronous period
+      8.2  Set wide size
+      8.3  Set maximum number of concurrent tagged commands
+      8.4  Set order type for tagged command
+      8.5  Set debug mode
+      8.6  Clear profile counters
+      8.7  Set flag (no_disc)
+      8.8  Set verbose level
+      8.9  Reset all logical units of a target
+      8.10 Abort all tasks of all logical units of a target
+9.  Configuration parameters
+10. Boot setup commands
+      10.1 Syntax
+      10.2 Available arguments
+             10.2.1  Master parity checking
+             10.2.2  Scsi parity checking
+             10.2.3  Scsi disconnections
+             10.2.4  Special features
+             10.2.5  Ultra SCSI support
+             10.2.6  Default number of tagged commands
+             10.2.7  Default synchronous period factor
+             10.2.8  Negotiate synchronous with all devices
+             10.2.9  Verbosity level
+             10.2.10 Debug mode
+             10.2.11 Burst max
+             10.2.12 LED support
+             10.2.13 Max wide
+             10.2.14 Differential mode
+             10.2.15 IRQ mode
+             10.2.16 Reverse probe
+             10.2.17 Fix up PCI configuration space
+             10.2.18 Serial NVRAM
+             10.2.19 Check SCSI BUS 
+             10.2.20 Exclude a host from being attached
+             10.2.21 Suggest a default SCSI id for hosts
+             10.2.22 Enable use of IMMEDIATE ARBITRATION
+      10.3 Advised boot setup commands
+      10.4 PCI configuration fix-up boot option
+      10.5 Serial NVRAM support boot option
+      10.6 SCSI BUS checking boot option
+      10.7 IMMEDIATE ARBITRATION boot option
+11. Some constants and flags of the ncr53c8xx.h header file
+12. Installation
+13. Architecture dependent features
+14. Known problems
+      14.1 Tagged commands with Iomega Jaz device
+      14.2 Device names change when another controller is added
+      14.3 Using only 8 bit devices with a WIDE SCSI controller.
+      14.4 Possible data corruption during a Memory Write and Invalidate
+      14.5 IRQ sharing problems
+15. SCSI problem troubleshooting
+      15.1 Problem tracking
+      15.2 Understanding hardware error reports
+16. Synchonous transfer negotiation tables
+      16.1 Synchronous timings for 53C875 and 53C860 Ultra-SCSI controllers
+      16.2 Synchronous timings for fast SCSI-2 53C8XX controllers
+17. Serial NVRAM support (by Richard Waltham)
+      17.1 Features
+      17.2 Symbios NVRAM layout
+      17.3 Tekram  NVRAM layout
+18. Support for Big Endian
+      18.1 Big Endian CPU
+      18.2 NCR chip in Big Endian mode of operations
+
+===============================================================================
+
+1. Introduction
+
+The initial Linux ncr53c8xx driver has been a port of the ncr driver from 
+FreeBSD that has been achieved in November 1995 by:
+          Gerard Roudier              <groudier@free.fr>
+
+The original driver has been written for 386bsd and FreeBSD by:
+          Wolfgang Stanglmeier        <wolf@cologne.de>
+          Stefan Esser                <se@mi.Uni-Koeln.de>
+
+It is now available as a bundle of 2 drivers:
+
+- ncr53c8xx generic driver that supports all the SYM53C8XX family including 
+  the ealiest 810 rev. 1, the latest 896 (2 channel LVD SCSI controller) and
+  the new 895A (1 channel LVD SCSI controller).
+- sym53c8xx enhanced driver (a.k.a. 896 drivers) that drops support of oldest 
+  chips in order to gain advantage of new features, as LOAD/STORE intructions 
+  available since the 810A and hardware phase mismatch available with the 
+  896 and the 895A.
+
+You can find technical information about the NCR 8xx family in the
+PCI-HOWTO written by Michael Will and in the SCSI-HOWTO written by
+Drew Eckhardt.
+
+Information about new chips is available at LSILOGIC web server:
+
+          http://www.lsilogic.com/
+
+SCSI standard documentations are available at SYMBIOS ftp server:
+
+          ftp://ftp.symbios.com/
+
+Usefull SCSI tools written by Eric Youngdale are available at tsx-11:
+
+          ftp://tsx-11.mit.edu/pub/linux/ALPHA/scsi/scsiinfo-X.Y.tar.gz
+          ftp://tsx-11.mit.edu/pub/linux/ALPHA/scsi/scsidev-X.Y.tar.gz
+
+These tools are not ALPHA but quite clean and work quite well.
+It is essential you have the 'scsiinfo' package.
+
+This short documentation describes the features of the generic and enhanced
+drivers, configuration parameters and control commands available through 
+the proc SCSI file system read / write operations.
+
+This driver has been tested OK with linux/i386, Linux/Alpha and Linux/PPC.
+
+Latest driver version and patches are available at:
+
+          ftp://ftp.tux.org/pub/people/gerard-roudier
+or
+          ftp://ftp.symbios.com/mirror/ftp.tux.org/pub/tux/roudier/drivers
+
+I am not a native speaker of English and there are probably lots of
+mistakes in this README file. Any help will be welcome.
+
+
+2. Supported chips and SCSI features
+
+The following features are supported for all chips:
+
+        Synchronous negotiation
+        Disconnection
+        Tagged command queuing
+        SCSI parity checking
+        Master parity checking
+
+"Wide negotiation" is supported for chips that allow it.  The
+following table shows some characteristics of NCR 8xx family chips 
+and what drivers support them.
+
+                                                  Supported by   Supported by
+       On board                                   the generic    the enhanced 
+Chip   SDMS BIOS   Wide   SCSI std.   Max. sync   driver         driver
+----   ---------   ----   ---------   ----------  ------------   -------------
+810        N         N      FAST10    10 MB/s        Y             N
+810A       N         N      FAST10    10 MB/s        Y             Y
+815        Y         N      FAST10    10 MB/s        Y             N
+825        Y         Y      FAST10    20 MB/s        Y             N
+825A       Y         Y      FAST10    20 MB/s        Y             Y
+860        N         N      FAST20    20 MB/s        Y             Y
+875        Y         Y      FAST20    40 MB/s        Y             Y
+876        Y         Y      FAST20    40 MB/s        Y             Y
+895        Y         Y      FAST40    80 MB/s        Y             Y
+895A       Y         Y      FAST40    80 MB/s        Y             Y
+896        Y         Y      FAST40    80 MB/s        Y             Y
+897        Y         Y      FAST40    80 MB/s        Y             Y
+1510D      Y         Y      FAST40    80 MB/s        Y             Y
+1010       Y         Y      FAST80   160 MB/s        N             Y
+1010_66*   Y         Y      FAST80   160 MB/s        N             Y
+
+* Chip supports 33MHz and 66MHz PCI buses.
+
+
+Summary of other supported features:
+
+Module:                allow to load the driver
+Memory mapped I/O:     increases performance
+Profiling information: read operations from the proc SCSI file system
+Control commands:      write operations to the proc SCSI file system
+Debugging information: written to syslog (expert only)
+Scatter / gather
+Shared interrupt
+Boot setup commands
+Serial NVRAM:          Symbios and Tekram formats
+
+
+3. Advantages of the enhanced 896 driver
+
+3.1 Optimized SCSI SCRIPTS.
+
+The 810A, 825A, 875, 895, 896 and 895A support new SCSI SCRIPTS instructions 
+named LOAD and STORE that allow to move up to 1 DWORD from/to an IO register 
+to/from memory much faster that the MOVE MEMORY instruction that is supported 
+by the 53c7xx and 53c8xx family.
+The LOAD/STORE instructions support absolute and DSA relative addressing 
+modes.  The SCSI SCRIPTS had been entirely rewritten using LOAD/STORE instead 
+of MOVE MEMORY instructions.
+
+3.2 New features of the SYM53C896 (64 bit PCI dual LVD SCSI controller)
+
+The 896 and the 895A allows handling of the phase mismatch context from 
+SCRIPTS (avoids the phase mismatch interrupt that stops the SCSI processor 
+until the C code has saved the context of the transfer).
+Implementing this without using LOAD/STORE instructions would be painfull 
+and I did'nt even want to try it.
+
+The 896 chip supports 64 bit PCI transactions and addressing, while the 
+895A supports 32 bit PCI transactions and 64 bit addressing.
+The SCRIPTS processor of these chips is not true 64 bit, but uses segment 
+registers for bit 32-63. Another interesting feature is that LOAD/STORE 
+instructions that address the on-chip RAM (8k) remain internal to the chip.
+
+Due to the use of LOAD/STORE SCRIPTS instructions, this driver does not 
+support the following chips:
+- SYM53C810 revision < 0x10 (16)
+- SYM53C815 all revisions
+- SYM53C825 revision < 0x10 (16)
+
+4. Memory mapped I/O versus normal I/O
+
+Memory mapped I/O has less latency than normal I/O.  Since
+linux-1.3.x, memory mapped I/O is used rather than normal I/O.  Memory
+mapped I/O seems to work fine on most hardware configurations, but
+some poorly designed motherboards may break this feature.
+
+The configuration option CONFIG_SCSI_NCR53C8XX_IOMAPPED forces the
+driver to use normal I/O in all cases.
+
+
+5. Tagged command queueing
+
+Queuing more than 1 command at a time to a device allows it to perform 
+optimizations based on actual head positions and its mechanical 
+characteristics. This feature may also reduce average command latency.
+In order to really gain advantage of this feature, devices must have 
+a reasonable cache size (No miracle is to be expected for a low-end 
+hard disk with 128 KB or less).
+Some kown SCSI devices do not properly support tagged command queuing.
+Generally, firmware revisions that fix this kind of problems are available 
+at respective vendor web/ftp sites.
+All I can say is that the hard disks I use on my machines behave well with 
+this driver with tagged command queuing enabled:
+
+- IBM S12 0662
+- Conner 1080S
+- Quantum Atlas I
+- Quantum Atlas II
+
+If your controller has NVRAM, you can configure this feature per target 
+from the user setup tool. The Tekram Setup program allows to tune the 
+maximum number of queued commands up to 32. The Symbios Setup only allows 
+to enable or disable this feature.
+
+The maximum number of simultaneous tagged commands queued to a device
+is currently set to 8 by default.  This value is suitable for most SCSI
+disks.  With large SCSI disks (>= 2GB, cache >= 512KB, average seek time
+<= 10 ms), using a larger value may give better performances.
+
+The sym53c8xx driver supports up to 255 commands per device, and the 
+generic ncr53c8xx driver supports up to 64, but using more than 32 is 
+generally not worth-while, unless you are using a very large disk or disk 
+array. It is noticeable that most of recent hard disks seem not to accept 
+more than 64 simultaneous commands. So, using more than 64 queued commands 
+is probably just resource wasting.
+
+If your controller does not have NVRAM or if it is managed by the SDMS 
+BIOS/SETUP, you can configure tagged queueing feature and device queue 
+depths from the boot command-line. For example:
+
+  ncr53c8xx=tags:4/t2t3q15-t4q7/t1u0q32
+
+will set tagged commands queue depths as follow:
+
+- target 2  all luns  on controller 0 --> 15
+- target 3  all luns  on controller 0 --> 15
+- target 4  all luns  on controller 0 -->  7
+- target 1  lun 0     on controller 1 --> 32
+- all other target/lun                -->  4
+
+In some special conditions, some SCSI disk firmwares may return a
+QUEUE FULL status for a SCSI command. This behaviour is managed by the
+driver using the following heuristic:
+
+- Each time a QUEUE FULL status is returned, tagged queue depth is reduced 
+  to the actual number of disconnected commands. 
+
+- Every 1000 successfully completed SCSI commands, if allowed by the
+  current limit, the maximum number of queueable commands is incremented.
+
+Since QUEUE FULL status reception and handling is resource wasting, the 
+driver notifies by default this problem to user by indicating the actual 
+number of commands used and their status, as well as its decision on the 
+device queue depth change.
+The heuristic used by the driver in handling QUEUE FULL ensures that the 
+impact on performances is not too bad. You can get rid of the messages by 
+setting verbose level to zero, as follow:
+
+1st method: boot your system using 'ncr53c8xx=verb:0' option.
+2nd method: apply "setverbose 0" control command to the proc fs entry 
+            corresponding to your controller after boot-up.
+
+6. Parity checking
+
+The driver supports SCSI parity checking and PCI bus master parity
+checking.  These features must be enabled in order to ensure safe data
+transfers.  However, some flawed devices or mother boards will have
+problems with parity. You can disable either PCI parity or SCSI parity 
+checking by entering appropriate options from the boot command line.
+(See 10: Boot setup commands).
+
+7. Profiling information
+
+Profiling information is available through the proc SCSI file system.
+Since gathering profiling information may impact performances, this 
+feature is disabled by default and requires a compilation configuration 
+option to be set to Y.
+
+The device associated with a host has the following pathname:
+
+          /proc/scsi/ncr53c8xx/N     (N=0,1,2 ....)
+
+Generally, only 1 board is used on hardware configuration, and that device is:
+          /proc/scsi/ncr53c8xx/0
+
+However, if the driver has been made as module, the number of the
+hosts is incremented each time the driver is loaded.
+
+In order to display profiling information, just enter:
+
+         cat /proc/scsi/ncr53c8xx/0
+
+and you will get something like the following text:
+
+-------------------------------------------------------
+General information:
+  Chip NCR53C810, device id 0x1, revision id 0x2
+  IO port address 0x6000, IRQ number 10
+  Using memory mapped IO at virtual address 0x282c000
+  Synchronous transfer period 25, max commands per lun 4
+Profiling information:
+  num_trans    = 18014
+  num_kbytes   = 671314
+  num_disc     = 25763
+  num_break    = 1673
+  num_int      = 1685
+  num_fly      = 18038
+  ms_setup     = 4940
+  ms_data      = 369940
+  ms_disc      = 183090
+  ms_post      = 1320
+-------------------------------------------------------
+
+General information is easy to understand. The device ID and the
+revision ID identify the SCSI chip as follows:
+
+Chip    Device id     Revision Id
+----    ---------     -----------
+810       0x1            <  0x10
+810A      0x1            >= 0x10
+815       0x4
+825       0x3            <  0x10
+860       0x6
+825A      0x3            >= 0x10
+875       0xf
+895       0xc
+
+The profiling information is updated upon completion of SCSI commands.
+A data structure is allocated and zeroed when the host adapter is
+attached. So, if the driver is a module, the profile counters are
+cleared each time the driver is loaded.  The "clearprof" command
+allows you to clear these counters at any time.
+
+The following counters are available:
+
+("num" prefix means "number of",
+"ms" means milli-seconds)
+
+num_trans
+        Number of completed commands
+        Example above: 18014 completed commands
+
+num_kbytes
+        Number of kbytes transferred
+        Example above: 671 MB transferred
+
+num_disc
+        Number of SCSI disconnections
+        Example above: 25763 SCSI disconnections
+
+num_break
+        number of script interruptions (phase mismatch)
+        Example above: 1673 script interruptions
+
+num_int
+        Number of interrupts other than "on the fly"
+        Example above: 1685 interruptions not "on the fly"
+
+num_fly
+        Number of interrupts "on the fly"
+        Example above: 18038 interruptions "on the fly"
+
+ms_setup
+        Elapsed time for SCSI commands setups
+        Example above: 4.94 seconds
+
+ms_data
+        Elapsed time for data transfers
+        Example above: 369.94 seconds spent for data transfer
+
+ms_disc
+        Elapsed time for SCSI disconnections
+        Example above: 183.09 seconds spent disconnected
+
+ms_post
+        Elapsed time for command post processing
+        (time from SCSI status get to command completion call)
+        Example above: 1.32 seconds spent for post processing
+
+Due to the 1/100 second tick of the system clock, "ms_post" time may
+be wrong.
+
+In the example above, we got 18038 interrupts "on the fly" and only
+1673 script breaks generally due to disconnections inside a segment 
+of the scatter list.
+
+
+8. Control commands
+
+Control commands can be sent to the driver with write operations to
+the proc SCSI file system. The generic command syntax is the
+following:
+
+      echo "<verb> <parameters>" >/proc/scsi/ncr53c8xx/0
+      (assumes controller number is 0)
+
+Using "all" for "<target>" parameter with the commands below will
+apply to all targets of the SCSI chain (except the controller).
+
+Available commands:
+
+8.1 Set minimum synchronous period factor
+
+    setsync <target> <period factor>
+
+    target:    target number
+    period:    minimum synchronous period.
+               Maximum speed = 1000/(4*period factor) except for special
+               cases below.
+
+    Specify a period of 255, to force asynchronous transfer mode.
+
+      10 means 25 nano-seconds synchronous period
+      11 means 30 nano-seconds synchronous period
+      12 means 50 nano-seconds synchronous period
+
+8.2 Set wide size
+
+    setwide <target> <size>
+
+    target:    target number
+    size:      0=8 bits, 1=16bits
+
+8.3 Set maximum number of concurrent tagged commands
+ 
+    settags <target> <tags>
+
+    target:    target number
+    tags:      number of concurrent tagged commands
+               must not be greater than SCSI_NCR_MAX_TAGS (default: 8)
+
+8.4 Set order type for tagged command
+
+    setorder <order>
+
+    order:     3 possible values:
+               simple: use SIMPLE TAG for all operations (read and write)
+               ordered: use ORDERED TAG for all operations
+               default: use default tag type,
+                        SIMPLE  TAG for read  operations
+                        ORDERED TAG for write operations
+
+
+8.5 Set debug mode
+
+    setdebug <list of debug flags>
+
+    Available debug flags:
+        alloc:   print info about memory allocations (ccb, lcb)
+        queue:   print info about insertions into the command start queue
+        result:  print sense data on CHECK CONDITION status
+        scatter: print info about the scatter process
+        scripts: print info about the script binding process
+        tiny:    print minimal debugging information
+        timing:  print timing information of the NCR chip
+        nego:    print information about SCSI negotiations
+        phase:   print information on script interruptions
+
+    Use "setdebug" with no argument to reset debug flags.
+
+
+8.6 Clear profile counters
+
+    clearprof
+
+    The profile counters are automatically cleared when the amount of
+    data transferred reaches 1000 GB in order to avoid overflow.
+    The "clearprof" command allows you to clear these counters at any time.
+
+
+8.7 Set flag (no_disc)
+ 
+    setflag <target> <flag>
+
+    target:    target number
+
+    For the moment, only one flag is available:
+
+        no_disc:   not allow target to disconnect.
+
+    Do not specify any flag in order to reset the flag. For example:
+    - setflag 4
+      will reset no_disc flag for target 4, so will allow it disconnections.
+    - setflag all
+      will allow disconnection for all devices on the SCSI bus.
+
+
+8.8 Set verbose level
+
+    setverbose #level
+
+    The driver default verbose level is 1. This command allows to change 
+    th driver verbose level after boot-up.
+
+8.9 Reset all logical units of a target
+
+    resetdev <target>
+
+    target:    target number
+    The driver will try to send a BUS DEVICE RESET message to the target.
+    (Only supported by the SYM53C8XX driver and provided for test purpose)
+
+8.10 Abort all tasks of all logical units of a target
+
+    cleardev <target>
+
+    target:    target number
+    The driver will try to send a ABORT message to all the logical units 
+    of the target.
+    (Only supported by the SYM53C8XX driver and provided for test purpose)
+
+
+9. Configuration parameters
+
+If the firmware of all your devices is perfect enough, all the
+features supported by the driver can be enabled at start-up.  However,
+if only one has a flaw for some SCSI feature, you can disable the
+support by the driver of this feature at linux start-up and enable
+this feature after boot-up only for devices that support it safely.
+
+CONFIG_SCSI_NCR53C8XX_PROFILE_SUPPORT  (default answer: n)
+    This option must be set for profiling information to be gathered 
+    and printed out through the proc file system. This features may 
+    impact performances.
+
+CONFIG_SCSI_NCR53C8XX_IOMAPPED       (default answer: n)
+    Answer "y" if you suspect your mother board to not allow memory mapped I/O.
+    May slow down performance a little.  This option is required by
+    Linux/PPC and is used no matter what you select here.  Linux/PPC
+    suffers no performance loss with this option since all IO is memory
+    mapped anyway.
+
+CONFIG_SCSI_NCR53C8XX_DEFAULT_TAGS    (default answer: 8)
+    Default tagged command queue depth.
+
+CONFIG_SCSI_NCR53C8XX_MAX_TAGS         (default answer: 8)
+    This option allows you to specify the maximum number of tagged commands 
+    that can be queued to a device. The maximum supported value is 32.
+
+CONFIG_SCSI_NCR53C8XX_SYNC            (default answer: 5)
+    This option allows you to specify the frequency in MHz the driver 
+    will use at boot time for synchronous data transfer negotiations.
+    This frequency can be changed later with the "setsync" control command.
+    0 means "asynchronous data transfers".
+
+CONFIG_SCSI_NCR53C8XX_FORCE_SYNC_NEGO (default answer: n)
+    Force synchronous negotiation for all SCSI-2 devices.
+    Some SCSI-2 devices do not report this feature in byte 7 of inquiry 
+    response but do support it properly (TAMARACK scanners for example).
+
+CONFIG_SCSI_NCR53C8XX_NO_DISCONNECT   (default and only reasonable answer: n)
+    If you suspect a device of yours does not properly support disconnections,
+    you can answer "y". Then, all SCSI devices will never disconnect the bus 
+    even while performing long SCSI operations.
+
+CONFIG_SCSI_NCR53C8XX_SYMBIOS_COMPAT
+    Genuine SYMBIOS boards use GPIO0 in output for controller LED and GPIO3 
+    bit as a flag indicating singled-ended/differential interface.
+    If all the boards of your system are genuine SYMBIOS boards or use
+    BIOS and drivers from SYMBIOS, you would want to enable this option.
+    This option must NOT be enabled if your system has at least one 53C8XX 
+    based scsi board with a vendor-specific BIOS.
+    For example, Tekram DC-390/U, DC-390/W and DC-390/F scsi controllers 
+    use a vendor-specific BIOS and are known to not use SYMBIOS compatible 
+    GPIO wiring. So, this option must not be enabled if your system has 
+    such a board installed.
+
+CONFIG_SCSI_NCR53C8XX_NVRAM_DETECT
+    Enable support for reading the serial NVRAM data on Symbios and
+    some Symbios compatible cards, and Tekram DC390W/U/F cards. Useful for
+    systems with more than one Symbios compatible controller where at least
+    one has a serial NVRAM, or for a system with a mixture of Symbios and
+    Tekram cards. Enables setting the boot order of host adaptors
+    to something other than the default order or "reverse probe" order. 
+    Also enables Symbios and Tekram cards to be distinguished so
+    CONFIG_SCSI_NCR53C8XX_SYMBIOS_COMPAT may be set in a system with a
+    mixture of Symbios and Tekram cards so the Symbios cards can make use of
+    the full range of Symbios features, differential, led pin, without
+    causing problems for the Tekram card(s).
+
+10. Boot setup commands
+
+10.1 Syntax
+
+Setup commands can be passed to the driver either at boot time or as a 
+string variable using 'insmod'.
+
+A boot setup command for the ncr53c8xx (sym53c8xx) driver begins with the 
+driver name "ncr53c8xx="(sym53c8xx). The kernel syntax parser then expects 
+an optionnal list of integers separated with comma followed by an optional 
+list of  comma-separated strings. Example of boot setup command under lilo 
+prompt:
+
+lilo: linux root=/dev/hda2 ncr53c8xx=tags:4,sync:10,debug:0x200
+
+- enable tagged commands, up to 4 tagged commands queued.
+- set synchronous negotiation speed to 10 Mega-transfers / second.
+- set DEBUG_NEGO flag.
+
+Since comma seems not to be allowed when defining a string variable using  
+'insmod', the driver also accepts <space> as option separator. 
+The following command will install driver module with the same options as 
+above.
+
+    insmod ncr53c8xx.o ncr53c8xx="tags:4 sync:10 debug:0x200"
+
+For the moment, the integer list of arguments is discarded by the driver. 
+It will be used in the future in order to allow a per controller setup.
+
+Each string argument must be specified as "keyword:value". Only lower-case 
+characters and digits are allowed.
+
+In a system that contains multiple 53C8xx adapters insmod will install the 
+specified driver on each adapter. To exclude a chip use the 'excl' keyword.
+
+The sequence of commands, 
+
+    insmod sym53c8xx sym53c8xx=excl:0x1400
+    insmod ncr53c8xx
+
+installs the sym53c8xx driver on all adapters except the one at IO port 
+address 0x1400 and then installs the ncr53c8xx driver to the adapter at IO 
+port address 0x1400.
+
+
+10.2 Available arguments
+
+10.2.1  Master parity checking
+        mpar:y     enabled
+        mpar:n     disabled
+
+10.2.2  Scsi parity checking
+        spar:y     enabled
+        spar:n     disabled
+
+10.2.3  Scsi disconnections
+        disc:y     enabled
+        disc:n     disabled
+ 
+10.2.4  Special features
+   Only apply to 810A, 825A, 860, 875 and 895 controllers.
+   Have no effect with other ones.
+        specf:y    (or 1) enabled
+        specf:n    (or 0) disabled
+        specf:3           enabled except Memory Write And Invalidate
+   The default driver setup is 'specf:3'. As a consequence, option 'specf:y' 
+   must be specified in the boot setup command to enable Memory Write And 
+   Invalidate.
+
+10.2.5  Ultra SCSI support
+   Only apply to 860, 875, 895, 895a, 896, 1010 and 1010_66 controllers.
+   Have no effect with other ones.
+        ultra:n    All ultra speeds enabled
+        ultra:2    Ultra2 enabled
+        ultra:1    Ultra enabled
+        ultra:0    Ultra speeds disabled
+
+10.2.6  Default number of tagged commands
+        tags:0     (or tags:1 ) tagged command queuing disabled
+        tags:#tags (#tags  > 1) tagged command queuing enabled
+  #tags will be truncated to the max queued commands configuration parameter.
+  This option also allows to specify a command queue depth for each device 
+  that support tagged command queueing.
+  Example:
+      ncr53c8xx=tags:10/t2t3q16-t5q24/t1u2q32
+               will set devices queue depth as follow:
+      - controller #0 target #2 and target #3                  -> 16 commands,
+      - controller #0 target #5                                -> 24 commands,
+      - controller #1 target #1 logical unit #2                -> 32 commands,
+      - all other logical units (all targets, all controllers) -> 10 commands.
+
+10.2.7  Default synchronous period factor
+        sync:255     disabled (asynchronous transfer mode)
+        sync:#factor
+  #factor = 10     Ultra-2 SCSI 40 Mega-transfers / second
+  #factor = 11     Ultra-2 SCSI 33 Mega-transfers / second
+  #factor < 25     Ultra   SCSI 20 Mega-transfers / second
+  #factor < 50     Fast    SCSI-2
+
+  In all cases, the driver will use the minimum transfer period supported by 
+  controllers according to NCR53C8XX chip type.
+
+10.2.8  Negotiate synchronous with all devices
+        (force sync nego)
+        fsn:y      enabled
+        fsn:n      disabled
+
+10.2.9  Verbosity level
+        verb:0     minimal
+        verb:1     normal
+        verb:2     too much
+
+10.2.10 Debug mode
+        debug:0  clear debug flags
+        debug:#x   set debug flags
+  #x is an integer value combining the following power-of-2 values:
+  DEBUG_ALLOC       0x1
+  DEBUG_PHASE       0x2
+  DEBUG_POLL        0x4
+  DEBUG_QUEUE       0x8
+  DEBUG_RESULT     0x10
+  DEBUG_SCATTER    0x20
+  DEBUG_SCRIPT     0x40
+  DEBUG_TINY       0x80
+  DEBUG_TIMING    0x100
+  DEBUG_NEGO      0x200
+  DEBUG_TAGS      0x400
+  DEBUG_FREEZE    0x800
+  DEBUG_RESTART  0x1000
+
+  You can play safely with DEBUG_NEGO. However, some of these flags may 
+  generate bunches of syslog messages. 
+
+10.2.11 Burst max
+        burst:0    burst disabled
+        burst:255  get burst length from initial IO register settings.
+        burst:#x   burst enabled (1<<#x burst transfers max)
+  #x is an integer value which is log base 2 of the burst transfers max.
+  The NCR53C875 and NCR53C825A support up to 128 burst transfers (#x = 7).
+  Other chips only support up to 16 (#x = 4).
+  This is a maximum value. The driver set the burst length according to chip 
+  and revision ids. By default the driver uses the maximum value supported 
+  by the chip.
+
+10.2.12 LED support
+        led:1      enable  LED support
+        led:0      disable LED support
+  Donnot enable LED support if your scsi board does not use SDMS BIOS.
+  (See 'Configuration parameters')
+
+10.2.13 Max wide
+        wide:1      wide scsi enabled
+        wide:0      wide scsi disabled
+  Some scsi boards use a 875 (ultra wide) and only supply narrow connectors.
+  If you have connected a wide device with a 50 pins to 68 pins cable 
+  converter, any accepted wide negotiation will break further data transfers.
+  In such a case, using "wide:0" in the bootup command will be helpfull. 
+
+10.2.14 Differential mode
+        diff:0  never set up diff mode
+        diff:1  set up diff mode if BIOS set it
+        diff:2  always set up diff mode
+        diff:3  set diff mode if GPIO3 is not set
+
+10.2.15 IRQ mode
+        irqm:0     always open drain
+        irqm:1     same as initial settings (assumed BIOS settings)
+        irqm:2     always totem pole
+        irqm:0x10  driver will not use SA_SHIRQ flag when requesting irq
+        irqm:0x20  driver will not use SA_INTERRUPT flag when requesting irq
+
+    (Bits 0x10 and 0x20 can be combined with hardware irq mode option)
+
+10.2.16 Reverse probe
+        revprob:n   probe chip ids from the PCI configuration in this order:
+                    810, 815, 820, 860, 875, 885, 895, 896
+        revprob:y   probe chip ids in the reverse order.
+
+10.2.17 Fix up PCI configuration space
+        pcifix:<option bits>
+
+    Available option bits:
+        0x0:   No attempt to fix PCI configuration space registers values.
+        0x1:   Set PCI cache-line size register if not set.
+        0x2:   Set write and invalidate bit in PCI command register.
+        0x4:   Increase if necessary PCI latency timer according to burst max.
+
+    Use 'pcifix:7' in order to allow the driver to fix up all PCI features.
+
+10.2.18 Serial NVRAM
+        nvram:n     do not look for serial NVRAM
+        nvram:y     test controllers for onboard serial NVRAM
+        (alternate binary form)
+        mvram=<bits options>
+        0x01   look for NVRAM  (equivalent to nvram=y)
+        0x02   ignore NVRAM "Synchronous negotiation" parameters for all devices
+        0x04   ignore NVRAM "Wide negotiation"  parameter for all devices
+        0x08   ignore NVRAM "Scan at boot time" parameter for all devices
+        0x80   also attach controllers set to OFF in the NVRAM (sym53c8xx only)
+
+10.2.19 Check SCSI BUS 
+        buschk:<option bits>
+
+    Available option bits:
+        0x0:   No check.
+        0x1:   Check and do not attach the controller on error.  
+        0x2:   Check and just warn on error.
+        0x4:   Disable SCSI bus integrity checking.
+
+10.2.20 Exclude a host from being attached
+        excl=<io_address>
+
+    Prevent host at a given io address from being attached.
+    For example 'ncr53c8xx=excl:0xb400,excl:0xc000' indicate to the 
+    ncr53c8xx driver not to attach hosts at address 0xb400 and 0xc000.
+
+10.2.21 Suggest a default SCSI id for hosts
+        hostid:255      no id suggested.
+        hostid:#x   (0 < x < 7) x suggested for hosts SCSI id.
+
+    If a host SCSI id is available from the NVRAM, the driver will ignore 
+    any value suggested as boot option. Otherwise, if a suggested value 
+    different from 255 has been supplied, it will use it. Otherwise, it will 
+    try to deduce the value previously set in the hardware and use value 
+    7 if the hardware value is zero.
+
+10.2.22 Enable use of IMMEDIATE ARBITRATION
+        (only supported by the sym53c8xx driver. See 10.7 for more details)
+        iarb:0    do not use this feature.
+        iarb:#x   use this feature according to bit fields as follow:
+
+    bit 0 (1) : enable IARB each time the initiator has been reselected 
+                when it arbitrated for the SCSI BUS.
+    (#x >> 4) : maximum number of successive settings of IARB if the initiator 
+                win arbitration and it has other commands to send to a device.
+
+Boot fail safe
+    safe:y      load the following assumed fail safe initial setup
+
+  master parity                 disabled                mpar:n
+  scsi parity                   enabled                 spar:y
+  disconnections                not allowed             disc:n
+  special features              disabled                specf:n
+  ultra scsi                    disabled                ultra:n
+  force sync negotiation        disabled                fsn:n
+  reverse probe                 disabled                revprob:n
+  PCI fix up                    disabled                pcifix:0
+  serial NVRAM                  enabled                 nvram:y
+  verbosity level               2                       verb:2
+  tagged command queuing        disabled                tags:0
+  synchronous negotiation       disabled                sync:255
+  debug flags                   none                    debug:0
+  burst length                  from BIOS settings      burst:255
+  LED support                   disabled                led:0
+  wide support                  disabled                wide:0
+  settle time                   10 seconds              settle:10
+  differential support          from BIOS settings      diff:1
+  irq mode                      from BIOS settings      irqm:1
+  SCSI BUS check                do not attach on error  buschk:1
+  immediate arbitration         disabled                iarb:0
+
+10.3 Advised boot setup commands
+
+If the driver has been configured with default options, the equivalent 
+boot setup is:
+
+   ncr53c8xx=mpar:y,spar:y,disc:y,specf:3,fsn:n,ultra:2,fsn:n,revprob:n,verb:1\
+             tags:0,sync:50,debug:0,burst:7,led:0,wide:1,settle:2,diff:0,irqm:0
+
+For an installation diskette or a safe but not fast system,
+boot setup can be:
+
+    ncr53c8xx=safe:y,mpar:y,disc:y
+    ncr53c8xx=safe:y,disc:y
+    ncr53c8xx=safe:y,mpar:y
+    ncr53c8xx=safe:y
+
+My personnal system works flawlessly with the following equivalent setup:
+
+   ncr53c8xx=mpar:y,spar:y,disc:y,specf:1,fsn:n,ultra:2,fsn:n,revprob:n,verb:1\
+             tags:32,sync:12,debug:0,burst:7,led:1,wide:1,settle:2,diff:0,irqm:0
+
+The driver prints its actual setup when verbosity level is 2. You can try 
+"ncr53c8xx=verb:2" to get the "static" setup of the driver, or add "verb:2" 
+to your boot setup command in order to check the actual setup the driver is 
+using.
+
+10.4 PCI configuration fix-up boot option
+
+pcifix:<option bits>
+
+Available option bits:
+    0x1:     Set PCI cache-line size register if not set.
+    0x2:     Set write and invalidate bit in PCI command register.
+
+Use 'pcifix:3' in order to allow the driver to fix both PCI features.
+
+These options only apply to new SYMBIOS chips 810A, 825A, 860, 875 
+and 895 and are only supported for Pentium and 486 class processors.
+Recent SYMBIOS 53C8XX scsi processors are able to use PCI read multiple 
+and PCI write and invalidate commands. These features require the 
+cache line size register to be properly set in the PCI configuration 
+space of the chips. On the other hand, chips will use PCI write and 
+invalidate commands only if the corresponding bit is set to 1 in the 
+PCI command register.
+
+Not all PCI bioses set the PCI cache line register and the PCI write and 
+invalidate bit in the PCI configuration space of 53C8XX chips.
+Optimized PCI accesses may be broken for some PCI/memory controllers or 
+make problems with some PCI boards.
+
+This fix-up worked flawlessly on my previous system.
+(MB Triton HX / 53C875 / 53C810A)
+I use these options at my own risks as you will do if you decide to 
+use them too.
+
+
+10.5 Serial NVRAM support boot option
+
+nvram:n     do not look for serial NVRAM
+nvram:y     test controllers for onboard serial NVRAM
+
+This option can also been entered as an hexadecimal value that allows 
+to control what information the driver will get from the NVRAM and what 
+information it will ignore.
+For details see '17. Serial NVRAM support'.
+
+When this option is enabled, the driver tries to detect all boards using 
+a Serial NVRAM. This memory is used to hold user set up parameters.
+
+The parameters the driver is able to get from the NVRAM depend on the 
+data format used, as follow:
+
+                                 Tekram format      Symbios format
+General and host parameters
+    Boot order                         N                   Y
+    Host SCSI ID                       Y                   Y
+    SCSI parity checking               Y                   Y
+    Verbose boot messages              N                   Y
+SCSI devices parameters
+    Synchronous transfer speed         Y                   Y
+    Wide 16 / Narrow                   Y                   Y
+    Tagged Command Queuing enabled     Y                   Y
+    Disconnections enabled             Y                   Y
+    Scan at boot time                  N                   Y
+
+In order to speed up the system boot, for each device configured without 
+the "scan at boot time" option, the driver forces an error on the 
+first TEST UNIT READY command received for this device.
+
+Some SDMS BIOS revisions seem to be unable to boot cleanly with very fast 
+hard disks. In such a situation you cannot configure the NVRAM with 
+optimized parameters value.
+
+The 'nvram' boot option can be entered in hexadecimal form in order 
+to ignore some options configured in the NVRAM, as follow:
+
+mvram=<bits options>
+      0x01   look for NVRAM  (equivalent to nvram=y)
+      0x02   ignore NVRAM "Synchronous negotiation" parameters for all devices
+      0x04   ignore NVRAM "Wide negotiation"  parameter for all devices
+      0x08   ignore NVRAM "Scan at boot time" parameter for all devices
+      0x80   also attach controllers set to OFF in the NVRAM (sym53c8xx only)
+
+Option 0x80 is only supported by the sym53c8xx driver and is disabled by 
+default. Result is that, by default (option not set), the sym53c8xx driver 
+will not attach controllers set to OFF in the NVRAM.
+
+The ncr53c8xx always tries to attach all the controllers. Option 0x80 has 
+not been added to the ncr53c8xx driver, since it has been reported to 
+confuse users who use this driver since a long time. If you desire a 
+controller not to be attached by the ncr53c8xx driver at Linux boot, you 
+must use the 'excl' driver boot option.
+
+10.6 SCSI BUS checking boot option.
+
+When this option is set to a non-zero value, the driver checks SCSI lines 
+logic state, 100 micro-seconds after having asserted the SCSI RESET line.
+The driver just reads SCSI lines and checks all lines read FALSE except RESET.
+Since SCSI devices shall release the BUS at most 800 nano-seconds after SCSI 
+RESET has been asserted, any signal to TRUE may indicate a SCSI BUS problem.
+Unfortunately, the following common SCSI BUS problems are not detected:
+- Only 1 terminator installed.
+- Misplaced terminators.
+- Bad quality terminators.
+On the other hand, either bad cabling, broken devices, not conformant 
+devices, ... may cause a SCSI signal to be wrong when te driver reads it.
+
+10.7 IMMEDIATE ARBITRATION boot option
+
+This option is only supported by the SYM53C8XX driver (not by the NCR53C8XX).
+
+SYMBIOS 53C8XX chips are able to arbitrate for the SCSI BUS as soon as they 
+have detected an expected disconnection (BUS FREE PHASE). For this process 
+to be started, bit 1 of SCNTL1 IO register must be set when the chip is 
+connected to the SCSI BUS.
+
+When this feature has been enabled for the current connection, the chip has 
+every chance to win arbitration if only devices with lower priority are 
+competing for the SCSI BUS. By the way, when the chip is using SCSI id 7, 
+then it will for sure win the next SCSI BUS arbitration.
+
+Since, there is no way to know what devices are trying to arbitrate for the 
+BUS, using this feature can be extremely unfair. So, you are not advised
+to enable it, or at most enable this feature for the case the chip lost 
+the previous arbitration (boot option 'iarb:1').
+
+This feature has the following advantages:
+
+a) Allow the initiator with ID 7 to win arbitration when it wants so.
+b) Overlap at least 4 micro-seconds of arbitration time with the execution 
+   of SCRIPTS that deal with the end of the current connection and that 
+   starts the next job.
+
+Hmmm... But (a) may just prevent other devices from reselecting the initiator, 
+and delay data transfers or status/completions, and (b) may just waste 
+SCSI BUS bandwidth if the SCRIPTS execution lasts more than 4 micro-seconds.
+
+The use of IARB needs the SCSI_NCR_IARB_SUPPORT option to have been defined 
+at compile time and the 'iarb' boot option to have been set to a non zero 
+value at boot time. It is not that useful for real work, but can be used 
+to stress SCSI devices or for some applications that can gain advantage of 
+it. By the way, if you experience badnesses like 'unexpected disconnections', 
+'bad reselections', etc... when using IARB on heavy IO load, you should not 
+be surprised, because force-feeding anything and blocking its arse at the 
+same time cannot work for a long time. :-))
+
+
+11. Some constants and flags of the ncr53c8xx.h header file
+
+Some of these are defined from the configuration parameters.  To
+change other "defines", you must edit the header file.  Do that only
+if you know what you are doing.
+
+SCSI_NCR_SETUP_SPECIAL_FEATURES (default: defined)
+        If defined, the driver will enable some special features according  
+        to chip and revision id.
+        For 810A, 860, 825A, 875 and 895 scsi chips, this option enables 
+        support of features that reduce load of PCI bus and memory accesses 
+        during  scsi transfer processing: burst op-code fetch, read multiple, 
+        read line, prefetch, cache line, write and invalidate, 
+        burst 128 (875 only), large dma fifo (875 only), offset 16 (875 only).
+        Can be changed by the following boot setup command:
+                ncr53c8xx=specf:n
+
+SCSI_NCR_IOMAPPED               (default: not defined)
+        If defined, normal I/O is forced.
+
+SCSI_NCR_SHARE_IRQ              (default: defined)
+        If defined, request shared IRQ.
+        
+SCSI_NCR_MAX_TAGS               (default: 8)
+        Maximum number of simultaneous tagged commands to a device.
+        Can be changed by "settags <target> <maxtags>"
+
+SCSI_NCR_SETUP_DEFAULT_SYNC     (default: 50)
+        Transfer period factor the driver will use at boot time for synchronous 
+        negotiation. 0 means asynchronous.
+        Can be changed by "setsync <target> <period factor>"
+
+SCSI_NCR_SETUP_DEFAULT_TAGS     (default: 8)
+        Default number of simultaneous tagged commands to a device.
+        < 1 means tagged command queuing disabled at start-up.
+
+SCSI_NCR_ALWAYS_SIMPLE_TAG      (default: defined)
+        Use SIMPLE TAG for read and write commands.
+        Can be changed by "setorder <ordered|simple|default>"
+
+SCSI_NCR_SETUP_DISCONNECTION    (default: defined)
+        If defined, targets are allowed to disconnect.
+
+SCSI_NCR_SETUP_FORCE_SYNC_NEGO  (default: not defined)
+        If defined, synchronous negotiation is tried for all SCSI-2 devices.
+        Can be changed by "setsync <target> <period>"
+
+SCSI_NCR_SETUP_MASTER_PARITY    (default: defined)
+        If defined, master parity checking is enabled.
+
+SCSI_NCR_SETUP_MASTER_PARITY    (default: defined)
+        If defined, SCSI parity checking is enabled.
+
+SCSI_NCR_PROFILE_SUPPORT        (default: not defined)
+        If defined, profiling information is gathered.
+
+SCSI_NCR_MAX_SCATTER            (default: 128)
+        Scatter list size of the driver ccb.
+
+SCSI_NCR_MAX_TARGET             (default: 16)
+        Max number of targets per host.
+
+SCSI_NCR_MAX_HOST               (default: 2)
+        Max number of host controllers.
+
+SCSI_NCR_SETTLE_TIME            (default: 2)
+        Number of seconds the driver will wait after reset.
+
+SCSI_NCR_TIMEOUT_ALERT          (default: 3)
+        If a pending command will time out after this amount of seconds,
+        an ordered tag is used for the next command.
+        Avoids timeouts for unordered tagged commands.
+
+SCSI_NCR_CAN_QUEUE              (default: 7*SCSI_NCR_MAX_TAGS)
+        Max number of commands that can be queued to a host.
+
+SCSI_NCR_CMD_PER_LUN            (default: SCSI_NCR_MAX_TAGS)
+        Max number of commands queued to a host for a device.
+
+SCSI_NCR_SG_TABLESIZE           (default: SCSI_NCR_MAX_SCATTER-1)
+        Max size of the Linux scatter/gather list.
+
+SCSI_NCR_MAX_LUN        (default: 8)
+        Max number of LUNs per target.
+
+
+12. Installation
+
+This driver is part of the linux kernel distribution.
+Driver files are located in the sub-directory "drivers/scsi" of the 
+kernel source tree.
+
+Driver files:
+
+        README.ncr53c8xx        : this file
+        ChangeLog.ncr53c8xx     : change log
+        ncr53c8xx.h             : definitions
+        ncr53c8xx.c             : the driver code
+
+New driver versions are made available separately in order to allow testing 
+changes and new features prior to including them into the linux kernel 
+distribution. The following URL provides informations on latest avalaible 
+patches: 
+
+      ftp://ftp.tux.org/pub/people/gerard-roudier/README
+
+
+13. Architecture dependent features.
+
+<Not yet written>
+
+
+14. Known problems
+
+14.1 Tagged commands with Iomega Jaz device
+
+I have not tried this device, however it has been reported to me the
+following: This device is capable of Tagged command queuing. However
+while spinning up, it rejects Tagged commands. This behaviour is
+conforms to 6.8.2 of SCSI-2 specifications. The current behaviour of
+the driver in that situation is not satisfying. So do not enable
+Tagged command queuing for devices that are able to spin down.  The
+other problem that may appear is timeouts. The only way to avoid
+timeouts seems to edit linux/drivers/scsi/sd.c and to increase the
+current timeout values.
+
+14.2 Device names change when another controller is added.
+
+When you add a new NCR53C8XX chip based controller to a system that already 
+has one or more controllers of this family, it may happen that the order 
+the driver registers them to the kernel causes problems due to device 
+name changes.
+When at least one controller uses NvRAM, SDMS BIOS version 4 allows you to 
+define the order the BIOS will scan the scsi boards. The driver attaches 
+controllers according to BIOS information if NvRAM detect option is set.
+
+If your controllers do not have NvRAM, you can:
+
+- Ask the driver to probe chip ids in reverse order from the boot command
+  line: ncr53c8xx=revprob:y
+- Make appropriate changes in the fstab.
+- Use the 'scsidev' tool from Eric Youngdale.
+
+14.3 Using only 8 bit devices with a WIDE SCSI controller.
+
+When only 8 bit NARROW devices are connected to a 16 bit WIDE SCSI controller, 
+you must ensure that lines of the wide part of the SCSI BUS are pulled-up.
+This can be achieved by ENABLING the WIDE TERMINATOR portion of the SCSI 
+controller card.
+The TYAN 1365 documentation revision 1.2 is not correct about such settings.
+(page 10, figure 3.3).
+
+14.4 Possible data corruption during a Memory Write and Invalidate
+
+This problem is described in SYMBIOS DEL 397, Part Number 69-039241, ITEM 4.
+
+In some complex situations, 53C875 chips revision <= 3 may start a PCI 
+Write and Invalidate Command at a not cache-line-aligned 4 DWORDS boundary.
+This is only possible when Cache Line Size is 8 DWORDS or greater.
+Pentium systems use a 8 DWORDS cache line size and so are concerned by 
+this chip bug, unlike i486 systems that use a 4 DWORDS cache line size.
+
+When this situation occurs, the chip may complete the Write and Invalidate 
+command after having only filled part of the last cache line involved in 
+the transfer, leaving to data corruption the remainder of this cache line.
+
+Not using Write And Invalidate obviously gets rid of this chip bug, and so 
+it is now the default setting of the driver.
+However, for people like me who want to enable this feature, I have added 
+part of a work-around suggested by SYMBIOS. This work-around resets the 
+addressing logic when the DATA IN phase is entered and so prevents the bug 
+from being triggered for the first SCSI MOVE of the phase. This work-around 
+should be enough according to the following:
+
+The only driver internal data structure that is greater than 8 DWORDS  and 
+that is moved by the SCRIPTS processor is the 'CCB header' that contains 
+the context of the SCSI transfer. This data structure is aligned on 8 DWORDS 
+boundary (Pentium Cache Line Size), and so is immune to this chip bug, at 
+least on Pentium systems.
+But the conditions of this bug can be met when a SCSI read command is 
+performed using a buffer that is 4 DWORDS but not cache-line aligned.
+This cannot happen under Linux when scatter/gather lists are used since 
+they only refer to system buffers that are well aligned. So, a work around 
+may only be needed under Linux when a scatter/gather list is not used and 
+when the SCSI DATA IN phase is reentered after a phase mismatch.
+
+14.5 IRQ sharing problems
+
+When an IRQ is shared by devices that are handled by different drivers, it 
+may happen that one driver complains about the request of the IRQ having 
+failed. Inder Linux-2.0, this may be due to one driver having requested the 
+IRQ using the SA_INTERRUPT flag but some other having requested the same IRQ 
+without this flag. Under both Linux-2.0 and linux-2.2, this may be caused by 
+one driver not having requested the IRQ with the SA_SHIRQ flag.
+
+By default, the ncr53c8xx and sym53c8xx drivers request IRQs with both the 
+SA_INTERRUPT and the SA_SHIRQ flag under Linux-2.0 and with only the SA_SHIRQ 
+flag under Linux-2.2.
+
+Under Linux-2.0, you can disable use of SA_INTERRUPT flag from the boot 
+command line by using the following option:
+
+     ncr53c8xx=irqm:0x20   (for the generic ncr53c8xx driver)
+     sym53c8xx=irqm:0x20   (for the sym53c8xx driver)
+
+If this does not fix the problem, then you may want to check how all other 
+drivers are requesting the IRQ and report the problem. Note that if at least 
+a single driver does not request the IRQ with the SA_SHIRQ flag (share IRQ), 
+then the request of the IRQ obviously will not succeed for all the drivers.
+
+15. SCSI problem troubleshooting
+
+15.1 Problem tracking
+
+Most SCSI problems are due to a non conformant SCSI bus or to buggy
+devices.  If infortunately you have SCSI problems, you can check the
+following things:
+
+- SCSI bus cables
+- terminations at both end of the SCSI chain
+- linux syslog messages (some of them may help you)
+
+If you do not find the source of problems, you can configure the
+driver with no features enabled.
+
+- only asynchronous data transfers
+- tagged commands disabled
+- disconnections not allowed
+
+Now, if your SCSI bus is ok, your system have every chance to work
+with this safe configuration but performances will not be optimal.
+
+If it still fails, then you can send your problem description to
+appropriate mailing lists or news-groups.  Send me a copy in order to
+be sure I will receive it.  Obviously, a bug in the driver code is
+possible.
+
+     My email address: Gerard Roudier <groudier@free.fr>
+
+Allowing disconnections is important if you use several devices on
+your SCSI bus but often causes problems with buggy devices.
+Synchronous data transfers increases throughput of fast devices like
+hard disks.  Good SCSI hard disks with a large cache gain advantage of
+tagged commands queuing.
+
+Try to enable one feature at a time with control commands.  For example:
+
+- echo "setsync all 25" >/proc/scsi/ncr53c8xx/0
+  Will enable fast synchronous data transfer negotiation for all targets.
+
+- echo "setflag 3" >/proc/scsi/ncr53c8xx/0
+  Will reset flags (no_disc) for target 3, and so will allow it to disconnect 
+  the SCSI Bus.
+
+- echo "settags 3 8" >/proc/scsi/ncr53c8xx/0
+  Will enable tagged command queuing for target 3 if that device supports it.
+
+Once you have found the device and the feature that cause problems, just 
+disable that feature for that device.
+
+15.2 Understanding hardware error reports
+
+When the driver detects an unexpected error condition, it may display a 
+message of the following pattern.
+
+sym53c876-0:1: ERROR (0:48) (1-21-65) (f/95) @ (script 7c0:19000000).
+sym53c876-0: script cmd = 19000000
+sym53c876-0: regdump: da 10 80 95 47 0f 01 07 75 01 81 21 80 01 09 00.
+
+Some fields in such a message may help you understand the cause of the 
+problem, as follows:
+
+sym53c876-0:1: ERROR (0:48) (1-21-65) (f/95) @ (script 7c0:19000000).
+............A.........B.C....D.E..F....G.H.......I.....J...K.......
+
+Field A : target number.
+  SCSI ID of the device the controller was talking with at the moment the 
+  error occurs.
+
+Field B : DSTAT io register (DMA STATUS)
+  Bit 0x40 : MDPE Master Data Parity Error
+             Data parity error detected on the PCI BUS.
+  Bit 0x20 : BF   Bus Fault
+             PCI bus fault condition detected
+  Bit 0x01 : IID  Illegal Instruction Detected
+             Set by the chip when it detects an Illegal Instruction format 
+             on some condition that makes an instruction illegal.
+  Bit 0x80 : DFE Dma Fifo Empty
+             Pure status bit that does not indicate an error.
+  If the reported DSTAT value contains a combination of MDPE (0x40), 
+  BF (0x20), then the cause may be likely due to a PCI BUS problem.
+
+Field C : SIST io register (SCSI Interrupt Status)
+  Bit 0x08 : SGE  SCSI GROSS ERROR
+             Indicates that the chip detected a severe error condition 
+             on the SCSI BUS that prevents the SCSI protocol from functioning
+             properly.
+  Bit 0x04 : UDC  Unexpected Disconnection
+             Indicates that the device released the SCSI BUS when the chip 
+             was not expecting this to happen. A device may behave so to 
+             indicate the SCSI initiator that an error condition not reportable              using the SCSI protocol has occurred.
+  Bit 0x02 : RST  SCSI BUS Reset
+             Generally SCSI targets do not reset the SCSI BUS, although any 
+             device on the BUS can reset it at any time.
+  Bit 0x01 : PAR  Parity
+             SCSI parity error detected.
+  On a faulty SCSI BUS, any error condition among SGE (0x08), UDC (0x04) and 
+  PAR (0x01) may be detected by the chip. If your SCSI system sometimes 
+  encounters such error conditions, especially SCSI GROSS ERROR, then a SCSI 
+  BUS problem is likely the cause of these errors.
+
+For fields D,E,F,G and H, you may look into the sym53c8xx_defs.h file 
+that contains some minimal comments on IO register bits.
+Field D : SOCL  Scsi Output Control Latch
+          This register reflects the state of the SCSI control lines the 
+          chip want to drive or compare against.
+Field E : SBCL  Scsi Bus Control Lines
+          Actual value of control lines on the SCSI BUS.
+Field F : SBDL  Scsi Bus Data Lines
+          Actual value of data lines on the SCSI BUS.
+Field G : SXFER  SCSI Transfer
+          Contains the setting of the Synchronous Period for output and 
+          the current Synchronous offset (offset 0 means asynchronous).
+Field H : SCNTL3 Scsi Control Register 3
+          Contains the setting of timing values for both asynchronous and 
+          synchronous data transfers. 
+
+Understanding Fields I, J, K and dumps requires to have good knowledge of 
+SCSI standards, chip cores functionnals and internal driver data structures.
+You are not required to decode and understand them, unless you want to help 
+maintain the driver code.
+
+16. Synchonous transfer negotiation tables
+
+Tables below have been created by calling the routine the driver uses
+for synchronisation negotiation timing calculation and chip setting.
+The first table corresponds to Ultra chips 53875 and 53C860 with 80 MHz 
+clock and 5 clock divisors.
+The second one has been calculated by setting the scsi clock to 40 Mhz 
+and using 4 clock divisors and so applies to all NCR53C8XX chips in fast 
+SCSI-2 mode.
+
+Periods are in nano-seconds and speeds are in Mega-transfers per second.
+1 Mega-transfers/second means 1 MB/s with 8 bits SCSI and 2 MB/s with 
+Wide16 SCSI.
+
+16.1 Synchronous timings for 53C895, 53C875 and 53C860 SCSI controllers
+
+ ----------------------------------------------
+ Negotiated                     NCR settings
+ Factor   Period   Speed        Period   Speed
+ ------   ------   ------       ------   ------
+ 10       25       40.000       25       40.000   (53C895 only)
+ 11       30.2     33.112       31.25    32.000   (53C895 only)
+ 12       50       20.000       50       20.000
+ 13       52       19.230       62       16.000
+ 14       56       17.857       62       16.000
+ 15       60       16.666       62       16.000
+ 16       64       15.625       75       13.333
+ 17       68       14.705       75       13.333
+ 18       72       13.888       75       13.333
+ 19       76       13.157       87       11.428
+ 20       80       12.500       87       11.428
+ 21       84       11.904       87       11.428
+ 22       88       11.363       93       10.666
+ 23       92       10.869       93       10.666
+ 24       96       10.416      100       10.000
+ 25      100       10.000      100       10.000
+ 26      104        9.615      112        8.888
+ 27      108        9.259      112        8.888
+ 28      112        8.928      112        8.888
+ 29      116        8.620      125        8.000
+ 30      120        8.333      125        8.000
+ 31      124        8.064      125        8.000
+ 32      128        7.812      131        7.619
+ 33      132        7.575      150        6.666
+ 34      136        7.352      150        6.666
+ 35      140        7.142      150        6.666
+ 36      144        6.944      150        6.666
+ 37      148        6.756      150        6.666
+ 38      152        6.578      175        5.714
+ 39      156        6.410      175        5.714
+ 40      160        6.250      175        5.714
+ 41      164        6.097      175        5.714
+ 42      168        5.952      175        5.714
+ 43      172        5.813      175        5.714
+ 44      176        5.681      187        5.333
+ 45      180        5.555      187        5.333
+ 46      184        5.434      187        5.333
+ 47      188        5.319      200        5.000
+ 48      192        5.208      200        5.000
+ 49      196        5.102      200        5.000
+
+
+16.2 Synchronous timings for fast SCSI-2 53C8XX controllers
+
+ ----------------------------------------------
+ Negotiated                     NCR settings
+ Factor   Period   Speed        Period   Speed
+ ------   ------   ------       ------   ------
+ 25      100       10.000      100       10.000
+ 26      104        9.615      125        8.000
+ 27      108        9.259      125        8.000
+ 28      112        8.928      125        8.000
+ 29      116        8.620      125        8.000
+ 30      120        8.333      125        8.000
+ 31      124        8.064      125        8.000
+ 32      128        7.812      131        7.619
+ 33      132        7.575      150        6.666
+ 34      136        7.352      150        6.666
+ 35      140        7.142      150        6.666
+ 36      144        6.944      150        6.666
+ 37      148        6.756      150        6.666
+ 38      152        6.578      175        5.714
+ 39      156        6.410      175        5.714
+ 40      160        6.250      175        5.714
+ 41      164        6.097      175        5.714
+ 42      168        5.952      175        5.714
+ 43      172        5.813      175        5.714
+ 44      176        5.681      187        5.333
+ 45      180        5.555      187        5.333
+ 46      184        5.434      187        5.333
+ 47      188        5.319      200        5.000
+ 48      192        5.208      200        5.000
+ 49      196        5.102      200        5.000
+
+
+17. Serial NVRAM (added by Richard Waltham: dormouse@farsrobt.demon.co.uk)
+
+17.1 Features
+
+Enabling serial NVRAM support enables detection of the serial NVRAM included
+on Symbios and some Symbios compatible host adaptors, and Tekram boards. The 
+serial NVRAM is used by Symbios and Tekram to hold set up parameters for the 
+host adaptor and it's attached drives.
+
+The Symbios NVRAM also holds data on the boot order of host adaptors in a
+system with more than one host adaptor. This enables the order of scanning
+the cards for drives to be changed from the default used during host adaptor
+detection.
+
+This can be done to a limited extent at the moment using "reverse probe" but
+this only changes the order of detection of different types of cards. The
+NVRAM boot order settings can do this as well as change the order the same
+types of cards are scanned in, something "reverse probe" cannot do.
+
+Tekram boards using Symbios chips, DC390W/F/U, which have NVRAM are detected
+and this is used to distinguish between Symbios compatible and Tekram host 
+adaptors. This is used to disable the Symbios compatible "diff" setting
+incorrectly set on Tekram boards if the CONFIG_SCSI_53C8XX_SYMBIOS_COMPAT 
+configuration parameter is set enabling both Symbios and Tekram boards to be 
+used together with the Symbios cards using all their features, including
+"diff" support. ("led pin" support for Symbios compatible cards can remain
+enabled when using Tekram cards. It does nothing useful for Tekram host
+adaptors but does not cause problems either.)
+
+
+17.2 Symbios NVRAM layout
+
+typical data at NVRAM address 0x100 (53c810a NVRAM)
+-----------------------------------------------------------
+00 00
+64 01
+8e 0b
+
+00 30 00 00 00 00 07 00 00 00 00 00 00 00 07 04 10 04 00 00 
+
+04 00 0f 00 00 10 00 50 00 00 01 00 00 62 
+04 00 03 00 00 10 00 58 00 00 01 00 00 63 
+04 00 01 00 00 10 00 48 00 00 01 00 00 61 
+00 00 00 00 00 00 00 00 00 00 00 00 00 00 
+
+0f 00 08 08 64 00 0a 00
+0f 00 08 08 64 00 0a 00 
+0f 00 08 08 64 00 0a 00 
+0f 00 08 08 64 00 0a 00 
+0f 00 08 08 64 00 0a 00 
+0f 00 08 08 64 00 0a 00 
+0f 00 08 08 64 00 0a 00 
+0f 00 08 08 64 00 0a 00 
+
+0f 00 08 08 64 00 0a 00 
+0f 00 08 08 64 00 0a 00 
+0f 00 08 08 64 00 0a 00 
+0f 00 08 08 64 00 0a 00 
+0f 00 08 08 64 00 0a 00 
+0f 00 08 08 64 00 0a 00 
+0f 00 08 08 64 00 0a 00 
+0f 00 08 08 64 00 0a 00 
+
+00 00 00 00 00 00 00 00 
+00 00 00 00 00 00 00 00 
+00 00 00 00 00 00 00 00 
+00 00 00 00 00 00 00 00 
+00 00 00 00 00 00 00 00 
+00 00 00 00 00 00 00 00 
+00 00 00 00 00 00 00 00 
+00 00 00 00 00 00 00 00 
+
+00 00 00 00 00 00 00 00 
+00 00 00 00 00 00 00 00 
+00 00 00 00 00 00 00 00 
+00 00 00 00 00 00 00 00 
+00 00 00 00 00 00 00 00 
+00 00 00 00 00 00 00 00 
+00 00 00 00 00 00 00 00 
+00 00 00 00 00 00 00 00 
+
+00 00 00 00 00 00 00 00 
+00 00 00 00 00 00 00 00 
+00 00 00 00 00 00 00 00 
+
+fe fe
+00 00
+00 00
+-----------------------------------------------------------
+NVRAM layout details
+
+NVRAM Address 0x000-0x0ff not used
+              0x100-0x26f initialised data
+              0x270-0x7ff not used
+
+general layout
+
+        header  -   6 bytes,
+        data    - 356 bytes (checksum is byte sum of this data)
+        trailer -   6 bytes
+                  ---
+        total     368 bytes
+
+data area layout
+
+        controller set up  -  20 bytes
+        boot configuration -  56 bytes (4x14 bytes)
+        device set up      - 128 bytes (16x8 bytes)
+        unused (spare?)    - 152 bytes (19x8 bytes)
+                             ---
+        total                356 bytes
+
+-----------------------------------------------------------
+header
+
+00 00   - ?? start marker
+64 01   - byte count (lsb/msb excludes header/trailer)
+8e 0b   - checksum (lsb/msb excludes header/trailer)
+-----------------------------------------------------------
+controller set up
+
+00 30 00 00 00 00 07 00 00 00 00 00 00 00 07 04 10 04 00 00
+                   |     |           |     |
+                   |     |           |      -- host ID
+                   |     |           |
+                   |     |            --Removable Media Support
+                   |     |               0x00 = none
+                   |     |               0x01 = Bootable Device
+                   |     |               0x02 = All with Media
+                   |     |
+                   |      --flag bits 2
+                   |        0x00000001= scan order hi->low
+                   |            (default 0x00 - scan low->hi)
+                    --flag bits 1
+                       0x00000001 scam enable
+                       0x00000010 parity enable
+                       0x00000100 verbose boot msgs
+
+remaining bytes unknown - they do not appear to change in my
+current set up for any of the controllers.
+
+default set up is identical for 53c810a and 53c875 NVRAM
+(Removable Media added Symbios BIOS version 4.09)
+-----------------------------------------------------------
+boot configuration
+
+boot order set by order of the devices in this table
+
+04 00 0f 00 00 10 00 50 00 00 01 00 00 62 -- 1st controller
+04 00 03 00 00 10 00 58 00 00 01 00 00 63    2nd controller
+04 00 01 00 00 10 00 48 00 00 01 00 00 61    3rd controller
+00 00 00 00 00 00 00 00 00 00 00 00 00 00    4th controller
+       |  |  |  |     |        |     |  |
+       |  |  |  |     |        |      ---- PCI io port adr
+       |  |  |  |     |         --0x01 init/scan at boot time
+       |  |  |  |      --PCI device/function number (0xdddddfff)
+       |  |   ----- ?? PCI vendor ID (lsb/msb)
+        ----PCI device ID (lsb/msb)
+
+?? use of this data is a guess but seems reasonable
+
+remaining bytes unknown - they do not appear to change in my
+current set up
+
+default set up is identical for 53c810a and 53c875 NVRAM
+-----------------------------------------------------------
+device set up (up to 16 devices - includes controller)
+
+0f 00 08 08 64 00 0a 00 - id 0
+0f 00 08 08 64 00 0a 00 
+0f 00 08 08 64 00 0a 00 
+0f 00 08 08 64 00 0a 00 
+0f 00 08 08 64 00 0a 00 
+0f 00 08 08 64 00 0a 00 
+0f 00 08 08 64 00 0a 00 
+0f 00 08 08 64 00 0a 00 
+
+0f 00 08 08 64 00 0a 00 
+0f 00 08 08 64 00 0a 00 
+0f 00 08 08 64 00 0a 00 
+0f 00 08 08 64 00 0a 00 
+0f 00 08 08 64 00 0a 00 
+0f 00 08 08 64 00 0a 00 
+0f 00 08 08 64 00 0a 00 
+0f 00 08 08 64 00 0a 00 - id 15
+ |     |  |  |     |  |
+ |     |  |  |      ----timeout (lsb/msb)
+ |     |  |   --synch period (0x?? 40 Mtrans/sec- fast 40) (probably 0x28)
+ |     |  |                  (0x30 20 Mtrans/sec- fast 20)
+ |     |  |                  (0x64 10 Mtrans/sec- fast )
+ |     |  |                  (0xc8  5 Mtrans/sec)
+ |     |  |                  (0x00  asynchronous)
+ |     |   -- ?? max sync offset (0x08 in NVRAM on 53c810a) 
+ |     |                         (0x10 in NVRAM on 53c875)
+ |      --device bus width (0x08 narrow)
+ |                         (0x10 16 bit wide)
+  --flag bits
+    0x00000001 - disconnect enabled
+    0x00000010 - scan at boot time
+    0x00000100 - scan luns
+    0x00001000 - queue tags enabled
+
+remaining bytes unknown - they do not appear to change in my
+current set up
+
+?? use of this data is a guess but seems reasonable 
+(but it could be max bus width)
+
+default set up for 53c810a NVRAM
+default set up for 53c875 NVRAM - bus width     - 0x10
+                                - sync offset ? - 0x10
+                                - sync period   - 0x30
+-----------------------------------------------------------
+?? spare device space (32 bit bus ??)
+
+00 00 00 00 00 00 00 00  (19x8bytes)
+.
+.
+00 00 00 00 00 00 00 00
+
+default set up is identical for 53c810a and 53c875 NVRAM
+-----------------------------------------------------------
+trailer
+
+fe fe   - ? end marker ?
+00 00
+00 00
+
+default set up is identical for 53c810a and 53c875 NVRAM
+-----------------------------------------------------------
+
+
+
+17.3 Tekram NVRAM layout
+
+nvram 64x16 (1024 bit)
+
+Drive settings
+
+Drive ID 0-15 (addr 0x0yyyy0 = device setup, yyyy = ID)
+              (addr 0x0yyyy1 = 0x0000)
+
+    x x x x  x x x x  x x x x  x x x x
+               | | |      | |  | | | |
+               | | |      | |  | | |  ----- parity check   0 - off
+               | | |      | |  | | |                       1 - on
+               | | |      | |  | | |
+               | | |      | |  | |  ------- sync neg       0 - off
+               | | |      | |  | |                         1 - on
+               | | |      | |  | |
+               | | |      | |  |  --------- disconnect     0 - off
+               | | |      | |  |                           1 - on
+               | | |      | |  |
+               | | |      | |   ----------- start cmd      0 - off
+               | | |      | |                              1 - on
+               | | |      | |
+               | | |      |  -------------- tagged cmds    0 - off
+               | | |      |                                1 - on
+               | | |      | 
+               | | |       ---------------- wide neg       0 - off
+               | | |                                       1 - on
+               | | |
+                --------------------------- sync rate      0 - 10.0 Mtrans/sec
+                                                           1 -  8.0
+                                                           2 -  6.6
+                                                           3 -  5.7
+                                                           4 -  5.0
+                                                           5 -  4.0
+                                                           6 -  3.0
+                                                           7 -  2.0
+                                                           7 -  2.0
+                                                           8 - 20.0
+                                                           9 - 16.7
+                                                           a - 13.9
+                                                           b - 11.9
+
+Global settings
+
+Host flags 0 (addr 0x100000, 32) 
+
+    x x x x  x x x x  x x x x  x x x x
+    | | | |  | | | |           | | | |
+    | | | |  | | | |            ----------- host ID    0x00 - 0x0f
+    | | | |  | | | |
+    | | | |  | | |  ----------------------- support for    0 - off
+    | | | |  | | |                          > 2 drives     1 - on
+    | | | |  | | | 
+    | | | |  | |  ------------------------- support drives 0 - off
+    | | | |  | |                            > 1Gbytes      1 - on
+    | | | |  | |
+    | | | |  |  --------------------------- bus reset on   0 - off
+    | | | |  |                                power on     1 - on
+    | | | |  |
+    | | | |   ----------------------------- active neg     0 - off
+    | | | |                                                1 - on
+    | | | |
+    | | |  -------------------------------- imm seek       0 - off
+    | | |                                                  1 - on
+    | | |
+    | |  ---------------------------------- scan luns      0 - off
+    | |                                                    1 - on
+    | |
+     -------------------------------------- removable      0 - disable
+                                            as BIOS dev    1 - boot device
+                                                           2 - all
+
+Host flags 1 (addr 0x100001, 33)
+
+    x x x x  x x x x  x x x x  x x x x
+               | | |             | | | 
+               | | |              --------- boot delay     0 -   3 sec
+               | | |                                       1 -   5
+               | | |                                       2 -  10
+               | | |                                       3 -  20
+               | | |                                       4 -  30
+               | | |                                       5 -  60
+               | | |                                       6 - 120
+               | | |
+                --------------------------- max tag cmds   0 -  2
+                                                           1 -  4
+                                                           2 -  8
+                                                           3 - 16
+                                                           4 - 32
+
+Host flags 2 (addr 0x100010, 34)
+
+    x x x x  x x x x  x x x x  x x x x
+                                     |
+                                      ----- F2/F6 enable   0 - off ???
+                                                           1 - on  ???
+
+checksum (addr 0x111111)
+
+checksum = 0x1234 - (sum addr 0-63)
+
+----------------------------------------------------------------------------
+
+default nvram data:
+
+0x0037 0x0000 0x0037 0x0000 0x0037 0x0000 0x0037 0x0000
+0x0037 0x0000 0x0037 0x0000 0x0037 0x0000 0x0037 0x0000
+0x0037 0x0000 0x0037 0x0000 0x0037 0x0000 0x0037 0x0000
+0x0037 0x0000 0x0037 0x0000 0x0037 0x0000 0x0037 0x0000 
+
+0x0f07 0x0400 0x0001 0x0000 0x0000 0x0000 0x0000 0x0000
+0x0000 0x0000 0x0000 0x0000 0x0000 0x0000 0x0000 0x0000
+0x0000 0x0000 0x0000 0x0000 0x0000 0x0000 0x0000 0x0000
+0x0000 0x0000 0x0000 0x0000 0x0000 0x0000 0x0000 0xfbbc
+
+
+18. Support for Big Endian
+
+The PCI local bus has been primarily designed for x86 architecture.
+As a consequence, PCI devices generally expect DWORDS using little endian 
+byte ordering.
+
+18.1 Big Endian CPU
+
+In order to support NCR chips on a Big Endian architecture the driver has to 
+perform byte reordering each time it is needed. This feature has been 
+added to the driver by Cort <cort@cs.nmt.edu> and is available in driver 
+version 2.5 and later ones. For the moment Big Endian support has only 
+been tested on Linux/PPC (PowerPC).
+
+18.2 NCR chip in Big Endian mode of operations
+
+It can be read in SYMBIOS documentation that some chips support a special 
+Big Endian mode, on paper: 53C815, 53C825A, 53C875, 53C875N, 53C895.
+This mode of operations is not software-selectable, but needs pin named 
+BigLit to be pulled-up. Using this mode, most of byte reorderings should 
+be avoided when the driver is running on a Big Endian CPU.
+Driver version 2.5 is also, in theory, ready for this feature.
+
+===============================================================================
+End of NCR53C8XX driver README file