1 .. SPDX-License-Identifier: GPL-2.0
2 .. include:: <isonum.txt>
3
4 =====================================================
5 Adaptec AHA-1520/1522 SCSI driver for Linux (aha152x)
6 =====================================================
7
8 Copyright |copy| 1993-1999 Jürgen Fischer <fischer@norbit.de>
9
10 TC1550 patches by Luuk van Dijk (ldz@xs4all.nl)
11
12
13 In Revision 2 the driver was modified a lot (especially the
14 bottom-half handler complete()).
15
16 The driver is much cleaner now, has support for the new
17 error handling code in 2.3, produced less cpu load (much
18 less polling loops), has slightly higher throughput (at
19 least on my ancient test box; a i486/33Mhz/20MB).
20
21
22 Configuration Arguments
23 =======================
24
25 ============ ======================================== ======================
26 IOPORT base io address (0x340/0x140)
27 IRQ interrupt level (9-12; default 11)
28 SCSI_ID scsi id of controller (0-7; default 7)
29 RECONNECT allow targets to disconnect from the bus (0/1; default 1 [on])
30 PARITY enable parity checking (0/1; default 1 [on])
31 SYNCHRONOUS enable synchronous transfers (0/1; default 1 [on])
32 DELAY: bus reset delay (default 100)
33 EXT_TRANS: enable extended translation (0/1: default 0 [off])
34 (see NOTES)
35 ============ ======================================== ======================
36
37 Compile Time Configuration
38 ==========================
39
40 (go into AHA152X in drivers/scsi/Makefile):
41
42 - DAUTOCONF
43 use configuration the controller reports (AHA-152x only)
44
45 - DSKIP_BIOSTEST
46 Don't test for BIOS signature (AHA-1510 or disabled BIOS)
47
48 - DSETUP0="{ IOPORT, IRQ, SCSI_ID, RECONNECT, PARITY, SYNCHRONOUS, DELAY, EXT_TRANS }"
49 override for the first controller
50
51 - DSETUP1="{ IOPORT, IRQ, SCSI_ID, RECONNECT, PARITY, SYNCHRONOUS, DELAY, EXT_TRANS }"
52 override for the second controller
53
54 - DAHA152X_DEBUG
55 enable debugging output
56
57 - DAHA152X_STAT
58 enable some statistics
59
60
61 LILO Command Line Options
62 =========================
63
64 ::
65
66 aha152x=<IOPORT>[,<IRQ>[,<SCSI-ID>[,<RECONNECT>[,<PARITY>[,<SYNCHRONOUS>[,<DELAY> [,<EXT_TRANS]]]]]]]
67
68 The normal configuration can be overridden by specifying a command line.
69 When you do this, the BIOS test is skipped. Entered values have to be
70 valid (known). Don't use values that aren't supported under normal
71 operation. If you think that you need other values: contact me.
72 For two controllers use the aha152x statement twice.
73
74
75 Symbols for Module Configuration
76 ================================
77
78 Choose from 2 alternatives:
79
80 1. specify everything (old)::
81
82 aha152x=IOPORT,IRQ,SCSI_ID,RECONNECT,PARITY,SYNCHRONOUS,DELAY,EXT_TRANS
83
84 configuration override for first controller
85
86 ::
87
88 aha152x1=IOPORT,IRQ,SCSI_ID,RECONNECT,PARITY,SYNCHRONOUS,DELAY,EXT_TRANS
89
90 configuration override for second controller
91
92 2. specify only what you need to (irq or io is required; new)
93
94 io=IOPORT0[,IOPORT1]
95 IOPORT for first and second controller
96
97 irq=IRQ0[,IRQ1]
98 IRQ for first and second controller
99
100 scsiid=SCSIID0[,SCSIID1]
101 SCSIID for first and second controller
102
103 reconnect=RECONNECT0[,RECONNECT1]
104 allow targets to disconnect for first and second controller
105
106 parity=PAR0[PAR1]
107 use parity for first and second controller
108
109 sync=SYNCHRONOUS0[,SYNCHRONOUS1]
110 enable synchronous transfers for first and second controller
111
112 delay=DELAY0[,DELAY1]
113 reset DELAY for first and second controller
114
115 exttrans=EXTTRANS0[,EXTTRANS1]
116 enable extended translation for first and second controller
117
118
119 If you use both alternatives the first will be taken.
120
121
122 Notes on EXT_TRANS
123 ==================
124
125 SCSI uses block numbers to address blocks/sectors on a device.
126 The BIOS uses a cylinder/head/sector addressing scheme (C/H/S)
127 scheme instead. DOS expects a BIOS or driver that understands this
128 C/H/S addressing.
129
130 The number of cylinders/heads/sectors is called geometry and is required
131 as base for requests in C/H/S addressing. SCSI only knows about the
132 total capacity of disks in blocks (sectors).
133
134 Therefore the SCSI BIOS/DOS driver has to calculate a logical/virtual
135 geometry just to be able to support that addressing scheme. The geometry
136 returned by the SCSI BIOS is a pure calculation and has nothing to
137 do with the real/physical geometry of the disk (which is usually
138 irrelevant anyway).
139
140 Basically this has no impact at all on Linux, because it also uses block
141 instead of C/H/S addressing. Unfortunately C/H/S addressing is also used
142 in the partition table and therefore every operating system has to know
143 the right geometry to be able to interpret it.
144
145 Moreover there are certain limitations to the C/H/S addressing scheme,
146 namely the address space is limited to up to 255 heads, up to 63 sectors
147 and a maximum of 1023 cylinders.
148
149 The AHA-1522 BIOS calculates the geometry by fixing the number of heads
150 to 64, the number of sectors to 32 and by calculating the number of
151 cylinders by dividing the capacity reported by the disk by 64*32 (1 MB).
152 This is considered to be the default translation.
153
154 With respect to the limit of 1023 cylinders using C/H/S you can only
155 address the first GB of your disk in the partition table. Therefore
156 BIOSes of some newer controllers based on the AIC-6260/6360 support
157 extended translation. This means that the BIOS uses 255 for heads,
158 63 for sectors and then divides the capacity of the disk by 255*63
159 (about 8 MB), as soon it sees a disk greater than 1 GB. That results
160 in a maximum of about 8 GB addressable diskspace in the partition table
161 (but there are already bigger disks out there today).
162
163 To make it even more complicated the translation mode might/might
164 not be configurable in certain BIOS setups.
165
166 This driver does some more or less failsafe guessing to get the
167 geometry right in most cases:
168
169 - for disks<1GB: use default translation (C/32/64)
170
171 - for disks>1GB:
172
173 - take current geometry from the partition table
174 (using scsicam_bios_param and accept only 'valid' geometries,
175 ie. either (C/32/64) or (C/63/255)). This can be extended translation
176 even if it's not enabled in the driver.
177
178 - if that fails, take extended translation if enabled by override,
179 kernel or module parameter, otherwise take default translation and
180 ask the user for verification. This might on not yet partitioned
181 disks.
182
183
184 References Used
185 ===============
186
187 "AIC-6260 SCSI Chip Specification", Adaptec Corporation.
188
189 "SCSI COMPUTER SYSTEM INTERFACE - 2 (SCSI-2)", X3T9.2/86-109 rev. 10h
190
191 "Writing a SCSI device driver for Linux", Rik Faith (faith@cs.unc.edu)
192
193 "Kernel Hacker's Guide", Michael K. Johnson (johnsonm@sunsite.unc.edu)
194
195 "Adaptec 1520/1522 User's Guide", Adaptec Corporation.
196
197 Michael K. Johnson (johnsonm@sunsite.unc.edu)
198
199 Drew Eckhardt (drew@cs.colorado.edu)
200
201 Eric Youngdale (eric@andante.org)
202
203 special thanks to Eric Youngdale for the free(!) supplying the
204 documentation on the chip.
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