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authorLinus Torvalds <torvalds@ppc970.osdl.org>2005-04-16 15:20:36 -0700
committerLinus Torvalds <torvalds@ppc970.osdl.org>2005-04-16 15:20:36 -0700
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tree0bba044c4ce775e45a88a51686b5d9f90697ea9d /Documentation/scsi/sym53c8xx_2.txt
downloadconfigs-2.6.12-rc2.tar.gz
Linux-2.6.12-rc2v2.6.12-rc2
Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!
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+The Linux SYM-2 driver documentation file
+
+Written by Gerard Roudier <groudier@free.fr>
+21 Rue Carnot
+95170 DEUIL LA BARRE - FRANCE
+
+Updated by Matthew Wilcox <matthew@wil.cx>
+
+2004-10-09
+===============================================================================
+
+1. Introduction
+2. Supported chips and SCSI features
+3. Advantages of this driver for newer chips.
+ 3.1 Optimized SCSI SCRIPTS
+ 3.2 New features appeared with the SYM53C896
+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 debug mode
+ 8.5 Set flag (no_disc)
+ 8.6 Set verbose level
+ 8.7 Reset all logical units of a target
+ 8.8 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 Default number of tagged commands
+ 10.2.2 Burst max
+ 10.2.3 LED support
+ 10.2.4 Differential mode
+ 10.2.5 IRQ mode
+ 10.2.6 Check SCSI BUS
+ 10.2.7 Suggest a default SCSI id for hosts
+ 10.2.8 Verbosity level
+ 10.2.9 Debug mode
+ 10.2.10 Settle delay
+ 10.2.11 Serial NVRAM
+ 10.2.12 Exclude a host from being attached
+ 10.3 Converting from old options
+ 10.4 SCSI BUS checking boot option
+11. SCSI problem troubleshooting
+ 15.1 Problem tracking
+ 15.2 Understanding hardware error reports
+12. Serial NVRAM support (by Richard Waltham)
+ 17.1 Features
+ 17.2 Symbios NVRAM layout
+ 17.3 Tekram NVRAM layout
+
+===============================================================================
+
+1. Introduction
+
+This driver supports the whole SYM53C8XX family of PCI-SCSI controllers.
+It also support the subset of LSI53C10XX PCI-SCSI controllers that are based
+on the SYM53C8XX SCRIPTS language.
+
+It replaces the sym53c8xx+ncr53c8xx driver bundle and shares its core code
+with the FreeBSD SYM-2 driver. The `glue' that allows this driver to work
+under Linux is contained in 2 files named sym_glue.h and sym_glue.c.
+Other drivers files are intended not to depend on the Operating System
+on which the driver is used.
+
+The history of this driver can be summerized as follows:
+
+1993: ncr driver written for 386bsd and FreeBSD by:
+ Wolfgang Stanglmeier <wolf@cologne.de>
+ Stefan Esser <se@mi.Uni-Koeln.de>
+
+1996: port of the ncr driver to Linux-1.2.13 and rename it ncr53c8xx.
+ Gerard Roudier
+
+1998: new sym53c8xx driver for Linux based on LOAD/STORE instruction and that
+ adds full support for the 896 but drops support for early NCR devices.
+ Gerard Roudier
+
+1999: port of the sym53c8xx driver to FreeBSD and support for the LSI53C1010
+ 33 MHz and 66MHz Ultra-3 controllers. The new driver is named `sym'.
+ Gerard Roudier
+
+2000: Add support for early NCR devices to FreeBSD `sym' driver.
+ Break the driver into several sources and separate the OS glue
+ code from the core code that can be shared among different O/Ses.
+ Write a glue code for Linux.
+ Gerard Roudier
+
+2004: Remove FreeBSD compatibility code. Remove support for versions of
+ Linux before 2.6. Start using Linux facilities.
+
+This README file addresses the Linux version of the driver. Under FreeBSD,
+the driver documentation is the sym.8 man page.
+
+Information about new chips is available at LSILOGIC web server:
+
+ http://www.lsilogic.com/
+
+SCSI standard documentations are available at T10 site:
+
+ http://www.t10.org/
+
+Useful SCSI tools written by Eric Youngdale are part of most Linux
+distributions:
+ scsiinfo: command line tool
+ scsi-config: TCL/Tk tool using scsiinfo
+
+2. Supported chips and SCSI features
+
+The following features are supported for all chips:
+
+ Synchronous negotiation
+ Disconnection
+ Tagged command queuing
+ SCSI parity checking
+ PCI Master parity checking
+
+Other features depends on chip capabilities.
+The driver notably uses optimized SCRIPTS for devices that support
+LOAD/STORE and handles PHASE MISMATCH from SCRIPTS for devices that
+support the corresponding feature.
+
+The following table shows some characteristics of the chip family.
+
+ On board LOAD/STORE HARDWARE
+Chip SDMS BIOS Wide SCSI std. Max. sync SCRIPTS PHASE MISMATCH
+---- --------- ---- --------- ---------- ---------- --------------
+810 N N FAST10 10 MB/s N N
+810A N N FAST10 10 MB/s Y N
+815 Y N FAST10 10 MB/s N N
+825 Y Y FAST10 20 MB/s N N
+825A Y Y FAST10 20 MB/s Y N
+860 N N FAST20 20 MB/s Y N
+875 Y Y FAST20 40 MB/s Y N
+875A Y Y FAST20 40 MB/s Y Y
+876 Y Y FAST20 40 MB/s Y N
+895 Y Y FAST40 80 MB/s Y N
+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 Y Y
+1010_66* Y Y FAST80 160 MB/s Y Y
+
+* Chip supports 33MHz and 66MHz PCI bus clock.
+
+
+Summary of other supported features:
+
+Module: allow to load the driver
+Memory mapped I/O: increases performance
+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 this driver for newer chips.
+
+3.1 Optimized SCSI SCRIPTS.
+
+All chips except the 810, 815 and 825, 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.
+
+Due to the lack of LOAD/STORE SCRIPTS instructions by earlier chips, this
+driver also incorporates a different SCRIPTS set based on MEMORY MOVE, in
+order to provide support for the entire SYM53C8XX chips family.
+
+3.2 New features appeared with the SYM53C896
+
+Newer chips (see above) 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).
+
+The 896 and 1010 chips support 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.
+
+4. Memory mapped I/O versus normal I/O
+
+Memory mapped I/O has less latency than normal I/O and is the recommended
+way for doing IO with PCI devices. Memory mapped I/O seems to work fine on
+most hardware configurations, but some poorly designed chipsets may break
+this feature. A configuration option is provided for normal I/O to be
+used but the driver defaults to MMIO.
+
+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 old 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 I never have had problem with tagged queuing using
+this driver and its predecessors. Hard disks that behaved correctly for
+me using tagged commands are the following:
+
+- IBM S12 0662
+- Conner 1080S
+- Quantum Atlas I
+- Quantum Atlas II
+- Seagate Cheetah I
+- Quantum Viking II
+- IBM DRVS
+- Quantum Atlas IV
+- Seagate Cheetah 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 16 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.
+
+This driver supports up to 255 commands per device, and but using more than
+64 is generally not worth-while, unless you are using a very large disk or
+disk arrays. 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:
+
+ sym53c8xx=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 200 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 'sym53c8xx=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. Some flawed devices or mother boards may have problems
+with parity. The options to defeat parity checking have been removed
+from the driver.
+
+7. Profiling information
+
+This driver does not provide profiling informations as did its predecessors.
+This feature was not this useful and added complexity to the code.
+As the driver code got more complex, I have decided to remove everything
+that didn't seem actually useful.
+
+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/sym53c8xx/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 0, to force asynchronous transfer mode.
+
+ 9 means 12.5 nano-seconds synchronous period
+ 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 configured (default: 16)
+
+8.4 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.
+
+
+8.5 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.
+
+
+8.6 Set verbose level
+
+ setverbose #level
+
+ The driver default verbose level is 1. This command allows to change
+ th driver verbose level after boot-up.
+
+8.7 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.
+
+8.8 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.
+
+
+9. Configuration parameters
+
+Under kernel configuration tools (make menuconfig, for example), it is
+possible to change some default driver 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.
+
+Configuration parameters:
+
+Use normal IO (default answer: n)
+ Answer "y" if you suspect your mother board to not allow memory mapped I/O.
+ May slow down performance a little.
+
+Default tagged command queue depth (default answer: 16)
+ Entering 0 defaults to tagged commands not being used.
+ This parameter can be specified from the boot command line.
+
+Maximum number of queued commands (default answer: 32)
+ This option allows you to specify the maximum number of tagged commands
+ that can be queued to a device. The maximum supported value is 255.
+
+Synchronous transfers frequency (default answer: 80)
+ This option allows you to specify the frequency in MHz the driver
+ will use at boot time for synchronous data transfer negotiations.
+ 0 means "asynchronous data transfers".
+
+10. Boot setup commands
+
+10.1 Syntax
+
+Setup commands can be passed to the driver either at boot time or as
+parameters to modprobe, as described in Documentation/kernel-parameters.txt
+
+Example of boot setup command under lilo prompt:
+
+lilo: linux root=/dev/sda2 sym53c8xx.cmd_per_lun=4 sym53c8xx.sync=10 sym53c8xx.debug=0x200
+
+- enable tagged commands, up to 4 tagged commands queued.
+- set synchronous negotiation speed to 10 Mega-transfers / second.
+- set DEBUG_NEGO flag.
+
+The following command will install the driver module with the same
+options as above.
+
+ modprobe sym53c8xx cmd_per_lun=4 sync=10 debug=0x200
+
+10.2 Available arguments
+
+10.2.1 Default number of tagged commands
+ cmd_per_lun=0 (or cmd_per_lun=1) tagged command queuing disabled
+ cmd_per_lun=#tags (#tags > 1) tagged command queuing enabled
+ #tags will be truncated to the max queued commands configuration parameter.
+
+10.2.2 Detailed control of tagged commands
+ This option allows you to specify a command queue depth for each device
+ that supports tagged command queueing.
+ Example:
+ tag_ctrl=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.
+
+10.2.3 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.
+ By default the driver uses the maximum value supported by the chip.
+
+10.2.4 LED support
+ led=1 enable LED support
+ led=0 disable LED support
+ Do not enable LED support if your scsi board does not use SDMS BIOS.
+ (See 'Configuration parameters')
+
+10.2.4 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
+
+10.2.5 IRQ mode
+ irqm=0 always open drain
+ irqm=1 same as initial settings (assumed BIOS settings)
+ irqm=2 always totem pole
+
+10.2.6 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.
+
+10.2.7 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.
+
+10.2.8 Verbosity level
+ verb=0 minimal
+ verb=1 normal
+ verb=2 too much
+
+10.2.9 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.
+
+10.2.10 Settle delay
+ settle=n delay for n seconds
+
+ After a bus reset, the driver will delay for n seconds before talking
+ to any device on the bus. The default is 3 seconds and safe mode will
+ default it to 10.
+
+10.2.11 Serial NVRAM
+ NB: option not currently implemented.
+ nvram=n do not look for serial NVRAM
+ nvram=y test controllers for onboard serial NVRAM
+ (alternate binary form)
+ nvram=<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)
+
+10.2.12 Exclude a host from being attached
+ excl=<io_address>,...
+
+ Prevent host at a given io address from being attached.
+ For example 'excl=0xb400,0xc000' indicate to the
+ driver not to attach hosts at address 0xb400 and 0xc000.
+
+10.3 Converting from old style options
+
+Previously, the sym2 driver accepted arguments of the form
+ sym53c8xx=tags:4,sync:10,debug:0x200
+
+As a result of the new module parameters, this is no longer available.
+Most of the options have remained the same, but tags has split into
+cmd_per_lun and tag_ctrl for its two different purposes. The sample above
+would be specified as:
+ modprobe sym53c8xx cmd_per_lun=4 sync=10 debug=0x200
+
+or on the kernel boot line as:
+ sym53c8xx.cmd_per_lun=4 sym53c8xx.sync=10 sym53c8xx.debug=0x200
+
+10.4 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.
+
+15. SCSI problem troubleshooting
+
+15.1 Problem tracking
+
+Most SCSI problems are due to a non conformant SCSI bus or too 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 or devices in the NVRAM with minimal features.
+
+- only asynchronous data transfers
+- tagged commands disabled
+- disconnections not allowed
+
+Now, if your SCSI bus is ok, your system has 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 cyrrent 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.
+
+15.2 Understanding hardware error reports
+
+When the driver detects an unexpected error condition, it may display a
+message of the following pattern.
+
+sym0:1: ERROR (0:48) (1-21-65) (f/95/0) @ (script 7c0:19000000).
+sym0: script cmd = 19000000
+sym0: 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:
+
+sym0:1: ERROR (0:48) (1-21-65) (f/95/0) @ (script 7c0:19000000).
+.....A.........B.C....D.E..F....G.H..I.......J.....K...L.......
+
+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.
+Field I : SCNTL4 Scsi Control Register 4
+ Only meaninful for 53C1010 Ultra3 controllers.
+
+Understanding Fields J, K, L 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.
+
+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 information is no longer used
+as it's fundamentally incompatible with the hotplug PCI model.
+
+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.)
+
+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.
+
+
+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
+
+
+===============================================================================
+End of Linux SYM-2 driver documentation file