184 lines
6.4 KiB
Plaintext
184 lines
6.4 KiB
Plaintext
$Id: README.aha152x,v 1.2 1999/12/25 15:32:30 fischer Exp fischer $
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Adaptec AHA-1520/1522 SCSI driver for Linux (aha152x)
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Copyright 1993-1999 Jürgen Fischer <fischer@norbit.de>
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TC1550 patches by Luuk van Dijk (ldz@xs4all.nl)
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In Revision 2 the driver was modified a lot (especially the
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bottom-half handler complete()).
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The driver is much cleaner now, has support for the new
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error handling code in 2.3, produced less cpu load (much
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less polling loops), has slightly higher throughput (at
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least on my ancient test box; a i486/33Mhz/20MB).
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CONFIGURATION ARGUMENTS:
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IOPORT base io address (0x340/0x140)
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IRQ interrupt level (9-12; default 11)
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SCSI_ID scsi id of controller (0-7; default 7)
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RECONNECT allow targets to disconnect from the bus (0/1; default 1 [on])
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PARITY enable parity checking (0/1; default 1 [on])
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SYNCHRONOUS enable synchronous transfers (0/1; default 1 [on])
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DELAY: bus reset delay (default 100)
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EXT_TRANS: enable extended translation (0/1: default 0 [off])
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(see NOTES)
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COMPILE TIME CONFIGURATION (go into AHA152X in drivers/scsi/Makefile):
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-DAUTOCONF
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use configuration the controller reports (AHA-152x only)
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-DSKIP_BIOSTEST
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Don't test for BIOS signature (AHA-1510 or disabled BIOS)
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-DSETUP0="{ IOPORT, IRQ, SCSI_ID, RECONNECT, PARITY, SYNCHRONOUS, DELAY, EXT_TRANS }"
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override for the first controller
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-DSETUP1="{ IOPORT, IRQ, SCSI_ID, RECONNECT, PARITY, SYNCHRONOUS, DELAY, EXT_TRANS }"
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override for the second controller
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-DAHA152X_DEBUG
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enable debugging output
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-DAHA152X_STAT
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enable some statistics
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LILO COMMAND LINE OPTIONS:
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aha152x=<IOPORT>[,<IRQ>[,<SCSI-ID>[,<RECONNECT>[,<PARITY>[,<SYNCHRONOUS>[,<DELAY> [,<EXT_TRANS]]]]]]]
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The normal configuration can be overridden by specifying a command line.
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When you do this, the BIOS test is skipped. Entered values have to be
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valid (known). Don't use values that aren't supported under normal
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operation. If you think that you need other values: contact me.
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For two controllers use the aha152x statement twice.
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SYMBOLS FOR MODULE CONFIGURATION:
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Choose from 2 alternatives:
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1. specify everything (old)
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aha152x=IOPORT,IRQ,SCSI_ID,RECONNECT,PARITY,SYNCHRONOUS,DELAY,EXT_TRANS
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configuration override for first controller
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aha152x1=IOPORT,IRQ,SCSI_ID,RECONNECT,PARITY,SYNCHRONOUS,DELAY,EXT_TRANS
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configuration override for second controller
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2. specify only what you need to (irq or io is required; new)
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io=IOPORT0[,IOPORT1]
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IOPORT for first and second controller
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irq=IRQ0[,IRQ1]
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IRQ for first and second controller
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scsiid=SCSIID0[,SCSIID1]
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SCSIID for first and second controller
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reconnect=RECONNECT0[,RECONNECT1]
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allow targets to disconnect for first and second controller
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parity=PAR0[PAR1]
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use parity for first and second controller
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sync=SYNCHRONOUS0[,SYNCHRONOUS1]
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enable synchronous transfers for first and second controller
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delay=DELAY0[,DELAY1]
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reset DELAY for first and second controller
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exttrans=EXTTRANS0[,EXTTRANS1]
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enable extended translation for first and second controller
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If you use both alternatives the first will be taken.
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NOTES ON EXT_TRANS:
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SCSI uses block numbers to address blocks/sectors on a device.
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The BIOS uses a cylinder/head/sector addressing scheme (C/H/S)
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scheme instead. DOS expects a BIOS or driver that understands this
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C/H/S addressing.
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The number of cylinders/heads/sectors is called geometry and is required
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as base for requests in C/H/S addressing. SCSI only knows about the
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total capacity of disks in blocks (sectors).
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Therefore the SCSI BIOS/DOS driver has to calculate a logical/virtual
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geometry just to be able to support that addressing scheme. The geometry
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returned by the SCSI BIOS is a pure calculation and has nothing to
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do with the real/physical geometry of the disk (which is usually
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irrelevant anyway).
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Basically this has no impact at all on Linux, because it also uses block
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instead of C/H/S addressing. Unfortunately C/H/S addressing is also used
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in the partition table and therefore every operating system has to know
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the right geometry to be able to interpret it.
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Moreover there are certain limitations to the C/H/S addressing scheme,
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namely the address space is limited to upto 255 heads, upto 63 sectors
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and a maximum of 1023 cylinders.
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The AHA-1522 BIOS calculates the geometry by fixing the number of heads
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to 64, the number of sectors to 32 and by calculating the number of
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cylinders by dividing the capacity reported by the disk by 64*32 (1 MB).
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This is considered to be the default translation.
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With respect to the limit of 1023 cylinders using C/H/S you can only
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address the first GB of your disk in the partition table. Therefore
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BIOSes of some newer controllers based on the AIC-6260/6360 support
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extended translation. This means that the BIOS uses 255 for heads,
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63 for sectors and then divides the capacity of the disk by 255*63
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(about 8 MB), as soon it sees a disk greater than 1 GB. That results
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in a maximum of about 8 GB addressable diskspace in the partition table
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(but there are already bigger disks out there today).
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To make it even more complicated the translation mode might/might
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not be configurable in certain BIOS setups.
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This driver does some more or less failsafe guessing to get the
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geometry right in most cases:
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- for disks<1GB: use default translation (C/32/64)
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- for disks>1GB:
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- take current geometry from the partition table
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(using scsicam_bios_param and accept only `valid' geometries,
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ie. either (C/32/64) or (C/63/255)). This can be extended translation
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even if it's not enabled in the driver.
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- if that fails, take extended translation if enabled by override,
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kernel or module parameter, otherwise take default translation and
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ask the user for verification. This might on not yet partitioned
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disks.
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REFERENCES USED:
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"AIC-6260 SCSI Chip Specification", Adaptec Corporation.
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"SCSI COMPUTER SYSTEM INTERFACE - 2 (SCSI-2)", X3T9.2/86-109 rev. 10h
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"Writing a SCSI device driver for Linux", Rik Faith (faith@cs.unc.edu)
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"Kernel Hacker's Guide", Michael K. Johnson (johnsonm@sunsite.unc.edu)
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"Adaptec 1520/1522 User's Guide", Adaptec Corporation.
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Michael K. Johnson (johnsonm@sunsite.unc.edu)
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Drew Eckhardt (drew@cs.colorado.edu)
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Eric Youngdale (eric@andante.org)
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special thanks to Eric Youngdale for the free(!) supplying the
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documentation on the chip.
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