0001 .. SPDX-License-Identifier: GPL-2.0
0002 .. include:: <isonum.txt>
0003
0004 =====================================================
0005 Adaptec AHA-1520/1522 SCSI driver for Linux (aha152x)
0006 =====================================================
0007
0008 Copyright |copy| 1993-1999 Jürgen Fischer <fischer@norbit.de>
0009
0010 TC1550 patches by Luuk van Dijk (ldz@xs4all.nl)
0011
0012
0013 In Revision 2 the driver was modified a lot (especially the
0014 bottom-half handler complete()).
0015
0016 The driver is much cleaner now, has support for the new
0017 error handling code in 2.3, produced less cpu load (much
0018 less polling loops), has slightly higher throughput (at
0019 least on my ancient test box; a i486/33Mhz/20MB).
0020
0021
0022 Configuration Arguments
0023 =======================
0024
0025 ============ ======================================== ======================
0026 IOPORT base io address (0x340/0x140)
0027 IRQ interrupt level (9-12; default 11)
0028 SCSI_ID scsi id of controller (0-7; default 7)
0029 RECONNECT allow targets to disconnect from the bus (0/1; default 1 [on])
0030 PARITY enable parity checking (0/1; default 1 [on])
0031 SYNCHRONOUS enable synchronous transfers (0/1; default 1 [on])
0032 DELAY: bus reset delay (default 100)
0033 EXT_TRANS: enable extended translation (0/1: default 0 [off])
0034 (see NOTES)
0035 ============ ======================================== ======================
0036
0037 Compile Time Configuration
0038 ==========================
0039
0040 (go into AHA152X in drivers/scsi/Makefile):
0041
0042 - DAUTOCONF
0043 use configuration the controller reports (AHA-152x only)
0044
0045 - DSKIP_BIOSTEST
0046 Don't test for BIOS signature (AHA-1510 or disabled BIOS)
0047
0048 - DSETUP0="{ IOPORT, IRQ, SCSI_ID, RECONNECT, PARITY, SYNCHRONOUS, DELAY, EXT_TRANS }"
0049 override for the first controller
0050
0051 - DSETUP1="{ IOPORT, IRQ, SCSI_ID, RECONNECT, PARITY, SYNCHRONOUS, DELAY, EXT_TRANS }"
0052 override for the second controller
0053
0054 - DAHA152X_DEBUG
0055 enable debugging output
0056
0057 - DAHA152X_STAT
0058 enable some statistics
0059
0060
0061 LILO Command Line Options
0062 =========================
0063
0064 ::
0065
0066 aha152x=<IOPORT>[,<IRQ>[,<SCSI-ID>[,<RECONNECT>[,<PARITY>[,<SYNCHRONOUS>[,<DELAY> [,<EXT_TRANS]]]]]]]
0067
0068 The normal configuration can be overridden by specifying a command line.
0069 When you do this, the BIOS test is skipped. Entered values have to be
0070 valid (known). Don't use values that aren't supported under normal
0071 operation. If you think that you need other values: contact me.
0072 For two controllers use the aha152x statement twice.
0073
0074
0075 Symbols for Module Configuration
0076 ================================
0077
0078 Choose from 2 alternatives:
0079
0080 1. specify everything (old)::
0081
0082 aha152x=IOPORT,IRQ,SCSI_ID,RECONNECT,PARITY,SYNCHRONOUS,DELAY,EXT_TRANS
0083
0084 configuration override for first controller
0085
0086 ::
0087
0088 aha152x1=IOPORT,IRQ,SCSI_ID,RECONNECT,PARITY,SYNCHRONOUS,DELAY,EXT_TRANS
0089
0090 configuration override for second controller
0091
0092 2. specify only what you need to (irq or io is required; new)
0093
0094 io=IOPORT0[,IOPORT1]
0095 IOPORT for first and second controller
0096
0097 irq=IRQ0[,IRQ1]
0098 IRQ for first and second controller
0099
0100 scsiid=SCSIID0[,SCSIID1]
0101 SCSIID for first and second controller
0102
0103 reconnect=RECONNECT0[,RECONNECT1]
0104 allow targets to disconnect for first and second controller
0105
0106 parity=PAR0[PAR1]
0107 use parity for first and second controller
0108
0109 sync=SYNCHRONOUS0[,SYNCHRONOUS1]
0110 enable synchronous transfers for first and second controller
0111
0112 delay=DELAY0[,DELAY1]
0113 reset DELAY for first and second controller
0114
0115 exttrans=EXTTRANS0[,EXTTRANS1]
0116 enable extended translation for first and second controller
0117
0118
0119 If you use both alternatives the first will be taken.
0120
0121
0122 Notes on EXT_TRANS
0123 ==================
0124
0125 SCSI uses block numbers to address blocks/sectors on a device.
0126 The BIOS uses a cylinder/head/sector addressing scheme (C/H/S)
0127 scheme instead. DOS expects a BIOS or driver that understands this
0128 C/H/S addressing.
0129
0130 The number of cylinders/heads/sectors is called geometry and is required
0131 as base for requests in C/H/S addressing. SCSI only knows about the
0132 total capacity of disks in blocks (sectors).
0133
0134 Therefore the SCSI BIOS/DOS driver has to calculate a logical/virtual
0135 geometry just to be able to support that addressing scheme. The geometry
0136 returned by the SCSI BIOS is a pure calculation and has nothing to
0137 do with the real/physical geometry of the disk (which is usually
0138 irrelevant anyway).
0139
0140 Basically this has no impact at all on Linux, because it also uses block
0141 instead of C/H/S addressing. Unfortunately C/H/S addressing is also used
0142 in the partition table and therefore every operating system has to know
0143 the right geometry to be able to interpret it.
0144
0145 Moreover there are certain limitations to the C/H/S addressing scheme,
0146 namely the address space is limited to up to 255 heads, up to 63 sectors
0147 and a maximum of 1023 cylinders.
0148
0149 The AHA-1522 BIOS calculates the geometry by fixing the number of heads
0150 to 64, the number of sectors to 32 and by calculating the number of
0151 cylinders by dividing the capacity reported by the disk by 64*32 (1 MB).
0152 This is considered to be the default translation.
0153
0154 With respect to the limit of 1023 cylinders using C/H/S you can only
0155 address the first GB of your disk in the partition table. Therefore
0156 BIOSes of some newer controllers based on the AIC-6260/6360 support
0157 extended translation. This means that the BIOS uses 255 for heads,
0158 63 for sectors and then divides the capacity of the disk by 255*63
0159 (about 8 MB), as soon it sees a disk greater than 1 GB. That results
0160 in a maximum of about 8 GB addressable diskspace in the partition table
0161 (but there are already bigger disks out there today).
0162
0163 To make it even more complicated the translation mode might/might
0164 not be configurable in certain BIOS setups.
0165
0166 This driver does some more or less failsafe guessing to get the
0167 geometry right in most cases:
0168
0169 - for disks<1GB: use default translation (C/32/64)
0170
0171 - for disks>1GB:
0172
0173 - take current geometry from the partition table
0174 (using scsicam_bios_param and accept only 'valid' geometries,
0175 ie. either (C/32/64) or (C/63/255)). This can be extended translation
0176 even if it's not enabled in the driver.
0177
0178 - if that fails, take extended translation if enabled by override,
0179 kernel or module parameter, otherwise take default translation and
0180 ask the user for verification. This might on not yet partitioned
0181 disks.
0182
0183
0184 References Used
0185 ===============
0186
0187 "AIC-6260 SCSI Chip Specification", Adaptec Corporation.
0188
0189 "SCSI COMPUTER SYSTEM INTERFACE - 2 (SCSI-2)", X3T9.2/86-109 rev. 10h
0190
0191 "Writing a SCSI device driver for Linux", Rik Faith (faith@cs.unc.edu)
0192
0193 "Kernel Hacker's Guide", Michael K. Johnson (johnsonm@sunsite.unc.edu)
0194
0195 "Adaptec 1520/1522 User's Guide", Adaptec Corporation.
0196
0197 Michael K. Johnson (johnsonm@sunsite.unc.edu)
0198
0199 Drew Eckhardt (drew@cs.colorado.edu)
0200
0201 Eric Youngdale (eric@andante.org)
0202
0203 special thanks to Eric Youngdale for the free(!) supplying the
0204 documentation on the chip.
