SYM(4)							   BSD Kernel Interfaces Manual 						    SYM(4)

NAME

     sym -- NCR/Symbios/LSI Logic 53C8XX PCI SCSI host adapter driver

SYNOPSIS

     To compile this driver into the kernel, place the following lines in your kernel configuration file:

	   device pci
	   device scbus
	   device sym

	   To disable PCI parity checking (needed for broken bridges):
	   options SYM_SETUP_PCI_PARITY=<boolean>

	   To control driver probing against HVD buses:
	   options SYM_SETUP_SCSI_DIFF=<bit combination>

	   To control chip attachment balancing between the ncr driver and this driver:
	   options SYM_SETUP_LP_PROBE_MAP=<bit combination>

     Alternatively, to load the driver as a module at boot time, place the following line in loader.conf(5):

	   sym_load="YES"

DESCRIPTION

     This driver provides support for the Symbios/LSI Logic 53C8XX PCI SCSI controllers.

     Driver features include support for wide SCSI busses and fast10, fast20, fast40 and fast80-dt synchronous data transfers depending on con-
     troller capabilities.  It also provides generic SCSI features such as tagged command queueing and auto-request sense.  This driver is config-
     ured by default for a maximum of 446 outstanding commands per bus, 8 LUNs per target and 64 tagged tasks per LUN.	These numbers are not so
     much limited by design as they are considered reasonable values for current SCSI technology.  These values can be increased by changing
     appropriate constants in driver header files (not recommended).

     This driver supports the entire Symbios 53C8XX family of PCI SCSI controllers.  It also offers the advantage of architectural improvements
     available only with newer chips.

     sym notably handles phase mismatch from SCRIPTS for the 53C896, 53C895A, and 53C1010 cores.  As a result, it guarantees that no more than 1
     interrupt per IO completion is delivered to the CPU, and that the SCRIPTS processor is never stalled waiting for CPU attention in normal sit-
     uations.

     sym also uses LOAD/STORE SCRIPTS instructions for chips that support it.  Only the early 810, 815 and 825 NCR chips do not support
     LOAD/STORE.  Use of LOAD/STORE instead of MEMORY MOVE allows SCRIPTS to access IO registers internal to the chip (no external PCI cycles).
     As a result, the driver guarantees that no PCI self-mastering will occur for chips that support LOAD/STORE.

     LOAD/STORE instructions are also faster than MEMORY MOVE because they do not involve the chip DMA FIFO and are coded on 2 DWORDs instead of
     3.

     For the early NCR 810, 815 and 825 chips, the driver uses a separate SCRIPTS set that uses MEMORY MOVE instructions for data movements.  This
     is because LOAD/STORE are not supported by these chips.

     HVD/LVD capable controllers (895, 895A, 896, and 897) report the actual bus mode in the STEST4 chip IO registers.	This feature allows the
     driver to safely probe against bus mode and to set up the chip accordingly.  By default the driver only supports HVD for these chips.  For
     other chips that can support HVD but not LVD, the driver has to probe implementation dependent registers (GPIO) in order to detect HVD bus
     mode.  Only HVD implementations that conform with Symbios Logic recommendations can be detected by the driver.  When the SYM_SETUP_SCSI_DIFF
     kernel option is assigned a value of 1, the driver will also probe against HVD for 825a, 875, 876 and 885 chips, assuming Symbios Logic com-
     patible implementation of HVD.

     When the SYM_SETUP_PCI_PARITY is assigned a value of 0, the driver will not enable PCI parity checking for 53C8XX devices.  PCI parity check-
     ing should not be an option for PCI SCSI controllers, but some systems have been reported to fail using 53C8XX chips, due to spurious or per-
     manent PCI parity errors detected.  This option is supplied for convenience but it is neither recommended nor supported.

     The generic ncr(4) driver also supports SYM53C8XX based PCI SCSI controllers, except for the SYM53C1010, which is only supported by the sym
     driver.

     By default, when both the ncr(4) and sym drivers are configured, the sym driver takes precedence over the ncr(4) driver.  The user can indi-
     cate a balancing of chip types between the two drivers by defining the SYM_SETUP_LP_PROBE_MAP kernel configuration option as follows:

     Bit     Devices to be attached by ncr instead
     0x01    53C810a, 53C860
     0x02    53C825a, 53C875, 53C876, 53C885, 53C895
     0x04    53C895a, 53C896, 53C897, 53C1510d
     0x40    53C810, 53C815, 53C825

     For example, if SYM_SETUP_LP_PROBE_MAP is supplied with the value 0x41, the ncr(4) driver will attach to 53C810, 53C815, 53C825, 53C810a, and
     53C860 based controllers, and the sym driver will attach to all other 53C8XX based controllers.

     When only the sym driver is configured, the SYM_SETUP_LP_PROBE_MAP option has no effect.  Thus, in this case, the sym driver will attach all
     53C8XX based controllers present in the system.

     This driver offers other options that are not currently exported to the user.  They are defined and documented in the sym_conf.h driver file.
     Changing these options is not recommended unless absolutely necessary.  Some of these options are planned to be exported through sysctl(3) or
     an equivalent mechanism in a future driver releases and therefore, no compatibility is guaranteed.

     At initialization, the driver tries to detect and read user settings from controller NVRAM.  The Symbios/Logic NVRAM layout and the Tekram
     NVRAM layout are currently supported.  If the reading of the NVRAM succeeds, the following settings are taken into account and reported to
     CAM:

     Host settings	     Symbios	Tekram
     SCSI parity checking    Y		N
     Host SCSI ident	     Y		Y
     Verbose messages	     Y		N
     Scan targets hi-lo      Y		N
     Avoid SCSI bus reset    Y		N

     Device settings	   Symbios    Tekram
     Synchronous period    Y	      Y
     SCSI bus width	   Y	      Y
     Queue tag enable	   Y	      Y
     Number of tags	   NA	      Y
     Disconnect enable	   Y	      Y
     Scan at boot time	   Y	      N
     Scan LUN		   Y	      N

     Devices that are configured as disabled for 'scan' in the NVRAM are not reported to CAM at system start-up.  They can be discovered later
     using the 'camcontrol rescan' command.

     The table below summarizes the main features and capabilities of the NCR/Symbios/LSI Logic 53C8XX family of PCI SCSI controllers.

     Chip	   Sync    Width   SRAM   PCI64   Supported
     sym53c810	   10MHz   8Bit    N	  N	  Y
     sym53c810a    10MHz   8Bit    N	  N	  Y
     sym53c815	   10MHz   8Bit    N	  N	  Y
     sym53c825	   10MHz   16Bit   N	  N	  Y
     sym53c825a    10MHz   16Bit   4KB	  N	  Y
     sym53c860	   20MHz   8Bit    N	  N	  Y
     sym53c875	   20MHz   16Bit   4KB	  N	  Y
     sym53c876	   20MHz   16Bit   4KB	  N	  Y
     sym53c885	   20MHz   16Bit   4KB	  N	  Y
     sym53c895	   40MHz   16Bit   4KB	  N	  Y
     sym53c895A    40MHz   16Bit   8KB	  N	  Y
     sym53c896	   40MHz   16Bit   8KB	  Y	  Y
     sym53c897	   40MHz   16Bit   8KB	  Y	  Y
     sym53c1510D   40MHz   16Bit   4KB	  Y	  Y
     sym53c1010    80MHz   16Bit   8KB	  Y	  Y

HARDWARE

     The sym driver provides support for the following Symbios/LSI Logic PCI SCSI controllers:

     o	 53C810
     o	 53C810A
     o	 53C815
     o	 53C825
     o	 53C825A
     o	 53C860
     o	 53C875
     o	 53C876
     o	 53C895
     o	 53C895A
     o	 53C896
     o	 53C897
     o	 53C1000
     o	 53C1000R
     o	 53C1010-33
     o	 53C1010-66
     o	 53C1510D

     The SCSI controllers supported by sym can be either embedded on a motherboard, or on one of the following add-on boards:

     o	 ASUS SC-200, SC-896
     o	 Data Technology DTC3130 (all variants)
     o	 DawiControl DC2976UW
     o	 Diamond FirePort (all)
     o	 I-O DATA SC-UPCI (PC-98)
     o	 Logitec LHA-521UA (PC-98)
     o	 NCR cards (all)
     o	 Symbios cards (all)
     o	 Tekram DC390W, 390U, 390F, 390U2B, 390U2W, 390U3D, and 390U3W
     o	 Tyan S1365

MISC

     The DEC KZPCA-AA is a rebadged SYM8952U.

SEE ALSO

     cd(4), da(4), ncr(4), sa(4), scsi(4), camcontrol(8)

HISTORY

     The sym driver appeared in FreeBSD 4.0.

AUTHORS

     The sym driver was written by Gerard Roudier and is derived from the Linux sym53c8xx driver from the same author.	The sym53c8xx driver is
     derived from the ncr53c8xx driver, which was ported from the FreeBSD ncr(4) driver to Linux-1.2.13.  The original ncr(4) driver was written
     for 386BSD and FreeBSD by Wolfgang Stanglmeier and Stefan Esser.

BUGS

     No known bugs.

BSD
								  August 19, 2004							       BSD