Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame^] | 1 | $Id: README.aha152x,v 1.2 1999/12/25 15:32:30 fischer Exp fischer $ |
| 2 | Adaptec AHA-1520/1522 SCSI driver for Linux (aha152x) |
| 3 | |
| 4 | Copyright 1993-1999 Jürgen Fischer <fischer@norbit.de> |
| 5 | TC1550 patches by Luuk van Dijk (ldz@xs4all.nl) |
| 6 | |
| 7 | |
| 8 | In Revision 2 the driver was modified a lot (especially the |
| 9 | bottom-half handler complete()). |
| 10 | |
| 11 | The driver is much cleaner now, has support for the new |
| 12 | error handling code in 2.3, produced less cpu load (much |
| 13 | less polling loops), has slightly higher throughput (at |
| 14 | least on my ancient test box; a i486/33Mhz/20MB). |
| 15 | |
| 16 | |
| 17 | CONFIGURATION ARGUMENTS: |
| 18 | |
| 19 | IOPORT base io address (0x340/0x140) |
| 20 | IRQ interrupt level (9-12; default 11) |
| 21 | SCSI_ID scsi id of controller (0-7; default 7) |
| 22 | RECONNECT allow targets to disconnect from the bus (0/1; default 1 [on]) |
| 23 | PARITY enable parity checking (0/1; default 1 [on]) |
| 24 | SYNCHRONOUS enable synchronous transfers (0/1; default 1 [on]) |
| 25 | DELAY: bus reset delay (default 100) |
| 26 | EXT_TRANS: enable extended translation (0/1: default 0 [off]) |
| 27 | (see NOTES) |
| 28 | |
| 29 | COMPILE TIME CONFIGURATION (go into AHA152X in drivers/scsi/Makefile): |
| 30 | |
| 31 | -DAUTOCONF |
| 32 | use configuration the controller reports (AHA-152x only) |
| 33 | |
| 34 | -DSKIP_BIOSTEST |
| 35 | Don't test for BIOS signature (AHA-1510 or disabled BIOS) |
| 36 | |
| 37 | -DSETUP0="{ IOPORT, IRQ, SCSI_ID, RECONNECT, PARITY, SYNCHRONOUS, DELAY, EXT_TRANS }" |
| 38 | override for the first controller |
| 39 | |
| 40 | -DSETUP1="{ IOPORT, IRQ, SCSI_ID, RECONNECT, PARITY, SYNCHRONOUS, DELAY, EXT_TRANS }" |
| 41 | override for the second controller |
| 42 | |
| 43 | -DAHA152X_DEBUG |
| 44 | enable debugging output |
| 45 | |
| 46 | -DAHA152X_STAT |
| 47 | enable some statistics |
| 48 | |
| 49 | |
| 50 | LILO COMMAND LINE OPTIONS: |
| 51 | |
| 52 | aha152x=<IOPORT>[,<IRQ>[,<SCSI-ID>[,<RECONNECT>[,<PARITY>[,<SYNCHRONOUS>[,<DELAY> [,<EXT_TRANS]]]]]]] |
| 53 | |
| 54 | The normal configuration can be overridden by specifying a command line. |
| 55 | When you do this, the BIOS test is skipped. Entered values have to be |
| 56 | valid (known). Don't use values that aren't supported under normal |
| 57 | operation. If you think that you need other values: contact me. |
| 58 | For two controllers use the aha152x statement twice. |
| 59 | |
| 60 | |
| 61 | SYMBOLS FOR MODULE CONFIGURATION: |
| 62 | |
| 63 | Choose from 2 alternatives: |
| 64 | |
| 65 | 1. specify everything (old) |
| 66 | |
| 67 | aha152x=IOPORT,IRQ,SCSI_ID,RECONNECT,PARITY,SYNCHRONOUS,DELAY,EXT_TRANS |
| 68 | configuration override for first controller |
| 69 | |
| 70 | |
| 71 | aha152x1=IOPORT,IRQ,SCSI_ID,RECONNECT,PARITY,SYNCHRONOUS,DELAY,EXT_TRANS |
| 72 | configuration override for second controller |
| 73 | |
| 74 | 2. specify only what you need to (irq or io is required; new) |
| 75 | |
| 76 | io=IOPORT0[,IOPORT1] |
| 77 | IOPORT for first and second controller |
| 78 | |
| 79 | irq=IRQ0[,IRQ1] |
| 80 | IRQ for first and second controller |
| 81 | |
| 82 | scsiid=SCSIID0[,SCSIID1] |
| 83 | SCSIID for first and second controller |
| 84 | |
| 85 | reconnect=RECONNECT0[,RECONNECT1] |
| 86 | allow targets to disconnect for first and second controller |
| 87 | |
| 88 | parity=PAR0[PAR1] |
| 89 | use parity for first and second controller |
| 90 | |
| 91 | sync=SYNCHRONOUS0[,SYNCHRONOUS1] |
| 92 | enable synchronous transfers for first and second controller |
| 93 | |
| 94 | delay=DELAY0[,DELAY1] |
| 95 | reset DELAY for first and second controller |
| 96 | |
| 97 | exttrans=EXTTRANS0[,EXTTRANS1] |
| 98 | enable extended translation for first and second controller |
| 99 | |
| 100 | |
| 101 | If you use both alternatives the first will be taken. |
| 102 | |
| 103 | |
| 104 | NOTES ON EXT_TRANS: |
| 105 | |
| 106 | SCSI uses block numbers to address blocks/sectors on a device. |
| 107 | The BIOS uses a cylinder/head/sector addressing scheme (C/H/S) |
| 108 | scheme instead. DOS expects a BIOS or driver that understands this |
| 109 | C/H/S addressing. |
| 110 | |
| 111 | The number of cylinders/heads/sectors is called geometry and is required |
| 112 | as base for requests in C/H/S addressing. SCSI only knows about the |
| 113 | total capacity of disks in blocks (sectors). |
| 114 | |
| 115 | Therefore the SCSI BIOS/DOS driver has to calculate a logical/virtual |
| 116 | geometry just to be able to support that addressing scheme. The geometry |
| 117 | returned by the SCSI BIOS is a pure calculation and has nothing to |
| 118 | do with the real/physical geometry of the disk (which is usually |
| 119 | irrelevant anyway). |
| 120 | |
| 121 | Basically this has no impact at all on Linux, because it also uses block |
| 122 | instead of C/H/S addressing. Unfortunately C/H/S addressing is also used |
| 123 | in the partition table and therefore every operating system has to know |
| 124 | the right geometry to be able to interpret it. |
| 125 | |
| 126 | Moreover there are certain limitations to the C/H/S addressing scheme, |
| 127 | namely the address space is limited to upto 255 heads, upto 63 sectors |
| 128 | and a maximum of 1023 cylinders. |
| 129 | |
| 130 | The AHA-1522 BIOS calculates the geometry by fixing the number of heads |
| 131 | to 64, the number of sectors to 32 and by calculating the number of |
| 132 | cylinders by dividing the capacity reported by the disk by 64*32 (1 MB). |
| 133 | This is considered to be the default translation. |
| 134 | |
| 135 | With respect to the limit of 1023 cylinders using C/H/S you can only |
| 136 | address the first GB of your disk in the partition table. Therefore |
| 137 | BIOSes of some newer controllers based on the AIC-6260/6360 support |
| 138 | extended translation. This means that the BIOS uses 255 for heads, |
| 139 | 63 for sectors and then divides the capacity of the disk by 255*63 |
| 140 | (about 8 MB), as soon it sees a disk greater than 1 GB. That results |
| 141 | in a maximum of about 8 GB addressable diskspace in the partition table |
| 142 | (but there are already bigger disks out there today). |
| 143 | |
| 144 | To make it even more complicated the translation mode might/might |
| 145 | not be configurable in certain BIOS setups. |
| 146 | |
| 147 | This driver does some more or less failsafe guessing to get the |
| 148 | geometry right in most cases: |
| 149 | |
| 150 | - for disks<1GB: use default translation (C/32/64) |
| 151 | |
| 152 | - for disks>1GB: |
| 153 | - take current geometry from the partition table |
| 154 | (using scsicam_bios_param and accept only `valid' geometries, |
| 155 | ie. either (C/32/64) or (C/63/255)). This can be extended translation |
| 156 | even if it's not enabled in the driver. |
| 157 | |
| 158 | - if that fails, take extended translation if enabled by override, |
| 159 | kernel or module parameter, otherwise take default translation and |
| 160 | ask the user for verification. This might on not yet partitioned |
| 161 | disks. |
| 162 | |
| 163 | |
| 164 | REFERENCES USED: |
| 165 | |
| 166 | "AIC-6260 SCSI Chip Specification", Adaptec Corporation. |
| 167 | |
| 168 | "SCSI COMPUTER SYSTEM INTERFACE - 2 (SCSI-2)", X3T9.2/86-109 rev. 10h |
| 169 | |
| 170 | "Writing a SCSI device driver for Linux", Rik Faith (faith@cs.unc.edu) |
| 171 | |
| 172 | "Kernel Hacker's Guide", Michael K. Johnson (johnsonm@sunsite.unc.edu) |
| 173 | |
| 174 | "Adaptec 1520/1522 User's Guide", Adaptec Corporation. |
| 175 | |
| 176 | Michael K. Johnson (johnsonm@sunsite.unc.edu) |
| 177 | |
| 178 | Drew Eckhardt (drew@cs.colorado.edu) |
| 179 | |
| 180 | Eric Youngdale (eric@andante.org) |
| 181 | |
| 182 | special thanks to Eric Youngdale for the free(!) supplying the |
| 183 | documentation on the chip. |