.\"	$NetBSD: ahc.4,v 1.36 2018/02/11 14:15:14 wiz Exp $
.\"
.\" Copyright (c) 1995, 1996, 1997, 1998, 2000
.\" 	Justin T. Gibbs.  All rights reserved.
.\"
.\" Redistribution and use in source and binary forms, with or without
.\" modification, are permitted provided that the following conditions
.\" are met:
.\" 1. Redistributions of source code must retain the above copyright
.\"    notice, this list of conditions and the following disclaimer.
.\" 2. Redistributions in binary form must reproduce the above copyright
.\"    notice, this list of conditions and the following disclaimer in the
.\"    documentation and/or other materials provided with the distribution.
.\" 3. The name of the author may not be used to endorse or promote products
.\"    derived from this software without specific prior written permission.
.\"
.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
.\" IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
.\" OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
.\" IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
.\" INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
.\" NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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.\" THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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.\" $FreeBSD: src/share/man/man4/ahc.4,v 1.22 2000/02/14 16:40:58 gibbs Exp $
.\"
.Dd July 16, 2007
.Dt AHC 4
.Os
.\".Os FreeBSD
.Sh NAME
.Nm ahc
.Nd Adaptec VL/EISA/PCI/CardBus SCSI host adapter driver
.Sh SYNOPSIS
.\" For one or more VL/EISA cards:
.\" .Cd device eisa
.\" .Cd device ahc
For VL cards:
.Cd "ahc0 at isa? port ? irq ?"
.Pp
For EISA cards:
.Cd "ahc* at eisa? slot ?"
.Pp
.\" For one or more PCI cards:
.\" .Cd device pci
.\" .Cd device ahc
For PCI cards:
.Cd "ahc* at pci? dev ? function ?"
.Pp
For CardBus cards:
.Cd "ahc* at cardbus? function ?"
.Pp
To allow PCI adapters to use memory mapped I/O if enabled:
.Cd options AHC_ALLOW_MEMIO
.Pp
Disable tagged queuing (avoids hangs on some hardware under load)
.Cd options AHC_NO_TAGS
.Pp
Change the default SCSI id for cards without a SEEPROM (default 7):
.Cd options AHC_CARDBUS_DEFAULT_SCSI_ID=integer
.Pp
.\" To configure one or more controllers to assume the target role:
.\" .Cd options AHC_TMODE_ENABLE <bitmask of units>
.\" .Pp
.\" For one or more SCSI buses:
.\" .Cd device scbus0 at ahc0
For SCSI buses:
.Cd scsibus* at ahc?
.Sh DESCRIPTION
.\" This driver provides access to the SCSI bus(es) connected to Adaptec
.\" AIC7770,
.\" AIC7850,
.\" AIC7860,
.\" AIC7870,
.\" AIC7880,
.\" AIC7890,
.\" AIC7891,
.\" AIC7892,
.\" AIC7895,
.\" AIC7896,
.\" AIC7897
.\" and
.\" AIC7899
.\" host adapter chips.
.\" These chips are found on many motherboards as well as the following
.\" Adaptec SCSI controller cards:
.\" 274X(W),
.\" 274X(T),
.\" 284X,
.\" 2910,
.\" 2915,
.\" 2920C,
.\" 2930C,
.\" 2930U2,
.\" 2940,
.\" 2940U,
.\" 2940AU,
.\" 2940UW,
.\" 2940UW Dual,
.\" 2940UW Pro,
.\" 2940U2W,
.\" 2940U2B,
.\" 2950U2W,
.\" 2950U2B,
.\" 19160B,
.\" 29160,
.\" 29160B,
.\" 29160N,
.\" 3940,
.\" 3940U,
.\" 3940AU,
.\" 3940UW,
.\" 3940AUW,
.\" 3940U2W,
.\" 3950U2,
.\" 3960,
.\" 39160,
.\" 3985,
.\" and
.\" 4944UW .
The
.Nm
device driver supports SCSI controllers based on Adaptec AIC77xx
and AIC78xx SCSI host adapter chips found on many motherboards as well as
Adaptec SCSI controller cards.
.Pp
Driver features include support for twin and wide buses,
fast, ultra or ultra2 synchronous transfers depending on controller type,
.\" tagged queuing, SCB paging, and target mode.
tagged queuing and SCB paging.
.Pp
Memory mapped I/O can be enabled for PCI devices with the
.Dq Dv AHC_ALLOW_MEMIO
configuration option.
Memory mapped I/O is more efficient than the alternative, programmed I/O.
Most PCI BIOSes will map devices so that either technique for communicating
with the card is available.
In some cases,
usually when the PCI device is sitting behind a PCI->PCI bridge,
the BIOS may fail to properly initialize the chip for memory mapped I/O.
The typical symptom of this problem is a system hang if memory mapped I/O
is attempted.
Most modern motherboards perform the initialization correctly and work fine
with this option enabled.
.Pp
.\" Individual controllers may be configured to operate in the target role
.\" through the
.\" .Dq Dv AHC_TMODE_ENABLE
.\" configuration option.
.\" The value assigned to this option should be a bitmap
.\" of all units where target mode is desired.
.\" For example, a value of 0x25, would enable target mode on units 0, 2, and 5.
.\" .Pp
Per target configuration performed in the SCSI-Select menu, accessible at boot
in non-EISA models,
or through an EISA configuration utility for EISA models,
is honored by this driver.
This includes synchronous/asynchronous transfers,
maximum synchronous negotiation rate,
wide transfers,
disconnection,
the host adapter's SCSI ID,
and,
in the case of EISA Twin Channel controllers,
the primary channel selection.
For systems that store non-volatile settings in a system specific manner
rather than a serial EEPROM directly connected to the aic7xxx controller,
the BIOS must be enabled for the driver to access this information.
This restriction applies to all EISA and many motherboard configurations.
.Pp
Note that I/O addresses are determined automatically by the probe routines,
but care should be taken when using a 284x
.Pq VESA No local bus controller
in an EISA system.
The jumpers setting the I/O area for the 284x should match the EISA
slot into which the card is inserted to prevent conflicts with other
EISA cards.
.Pp
Performance and feature sets vary throughout the aic7xxx product line.
The following table provides a comparison of the different chips supported
by the
.Nm
driver.
Note that wide and twin channel features, although always supported
by a particular chip, may be disabled in a particular motherboard
or card design.
.Bl -column "aic7895c" "MIPS" "EISA/VL" "MaxSync" "MaxWidth" "SCBs" "2 3 4 5 6 7 8"
.It Sy Chip  Ta Sy MIPS Ta Sy Bus Ta Sy MaxSync Ta Sy MaxWidth Ta Sy SCBs Ta Sy Features
.It aic7770  Ta 10   Ta EISA/VL Ta 10MHz   Ta 16Bit    Ta  4   Ta 1
.It aic7850  Ta 10   Ta PCI/32  Ta 10MHz   Ta  8Bit    Ta  3   Ta ""
.It aic7860  Ta 10   Ta PCI/32  Ta 20MHz   Ta  8Bit    Ta  3   Ta ""
.It aic7870  Ta 10   Ta PCI/32  Ta 10MHz   Ta 16Bit    Ta 16   Ta ""
.It aic7880  Ta 10   Ta PCI/32  Ta 20MHz   Ta 16Bit    Ta 16   Ta ""
.It aic7890  Ta 20   Ta PCI/32  Ta 40MHz   Ta 16Bit    Ta 16   Ta 3 4 5 6 7 8
.It aic7891  Ta 20   Ta PCI/64  Ta 40MHz   Ta 16Bit    Ta 16   Ta 3 4 5 6 7 8
.It aic7892  Ta 20   Ta PCI/64  Ta 80MHz   Ta 16Bit    Ta 16   Ta 3 4 5 6 7 8
.It aic7895  Ta 15   Ta PCI/32  Ta 20MHz   Ta 16Bit    Ta 16   Ta 2 3 4 5
.It aic7895C Ta 15   Ta PCI/32  Ta 20MHz   Ta 16Bit    Ta 16   Ta 2 3 4 5     8
.It aic7896  Ta 20   Ta PCI/32  Ta 40MHz   Ta 16Bit    Ta 16   Ta 2 3 4 5 6 7 8
.It aic7897  Ta 20   Ta PCI/64  Ta 40MHz   Ta 16Bit    Ta 16   Ta 2 3 4 5 6 7 8
.It aic7899  Ta 20   Ta PCI/64  Ta 80MHz   Ta 16Bit    Ta 16   Ta 2 3 4 5 6 7 8
.El
.Bl -enum -compact
.It
Multiplexed Twin Channel Device - One controller servicing two buses.
.It
Multi-function Twin Channel Device - Two controllers on one chip.
.It
Command Channel Secondary DMA Engine - Allows scatter gather list and
SCB prefetch.
.It
64 Byte SCB Support - SCSI CDB is embedded in the SCB to eliminate an extra DMA.
.It
Block Move Instruction Support - Doubles the speed of certain sequencer
operations.
.It
.Sq Bayonet
style Scatter Gather Engine - Improves S/G prefetch performance.
.It
Queuing Registers - Allows queuing of new transactions without pausing the
sequencer.
.It
Multiple Target IDs - Allows the controller to respond to selection as a
target on multiple SCSI IDs.
.El
.Sh HARDWARE
Supported SCSI controllers include:
.Bl -item -offset indent
.It
Adaptec AHA-2742W EISA Fast Wide SCSI adapter
.It
Adaptec AHA-274xAT EISA dual channel Fast SCSI adapter
.It
Adaptec AHA-284x VL Fast SCSI adapter
.It
Adaptec AHA-2910 PCI Fast SCSI adapter (no SCSI BIOS)
.It
Adaptec AHA-2915 PCI Fast SCSI adapter (no SCSI BIOS)
.It
Adaptec AHA-2920C PCI Fast SCSI adapter
.Bl -item -offset indent
.It
Note:
Adaptec AHA-2920/A which use the Future Domain's chips are not supported
by this driver.
.El
.It
Adaptec AHA-2930C PCI Ultra SCSI adapter
.It
Adaptec AHA-2930U2 PCI Ultra2 Wide LVD SCSI adapter
.It
Adaptec AHA-2940 PCI Fast SCSI adapter
.It
Adaptec AHA-2940U PCI Ultra SCSI adapter
.It
Adaptec AHA-2940AU PCI Ultra SCSI adapter
.It
Adaptec AHA-2940UW PCI Ultra Wide SCSI adapter
.It
Adaptec AHA-2940UW Dual PCI dual channel Ultra Wide SCSI adapter
.It
Adaptec AHA-2940UW Pro PCI Ultra Wide SCSI adapter
.It
Adaptec AHA-2940U2W PCI Ultra2 Wide LVD SCSI adapter
.It
Adaptec AHA-2940U2B PCI Ultra2 Wide LVD SCSI adapter
.It
Adaptec AHA-2944W PCI Fast Wide Differential SCSI adapter
.It
Adaptec AHA-2944UW PCI Ultra Wide Differential SCSI adapter
.It
Adaptec AHA-2950U2W
.It
Adaptec AHA-2950U2B 64bit PCI Ultra2 Wide LVD SCSI adapter
.It
Adaptec AHA-19160B PCI Ultra160 Wide LVD SCSI adapter
.It
Adaptec ASC-29160 PCI Ultra160 Wide LVD SCSI adapter
.It
Adaptec AHA-29160N PCI Ultra160 Wide LVD SCSI adapter
.It
Adaptec AHA-29160B 64bit PCI Ultra160 Wide LVD SCSI adapter
.It
Adaptec AHA-3940 PCI dual channel Fast SCSI adapter
.It
Adaptec AHA-3940U PCI dual channel Ultra SCSI adapter
.It
Adaptec AHA-3940AU PCI dual channel Ultra SCSI adapter
.It
Adaptec AHA-3940UW PCI dual channel Ultra Wide SCSI adapter
.It
Adaptec AHA-3940AUW PCI dual channel Ultra Wide SCSI adapter
.It
Adaptec AHA-3940U2W PCI dual channel Ultra2 Wide LVD SCSI adapter
.It
Adaptec AHA-3950U2 64bit PCI dual channel Ultra2 Wide LVD SCSI adapter
.It
Adaptec AHA-3960 64bit PCI dual channel Ultra160 Wide LVD SCSI adapter
.It
Adaptec AHA-3985 PCI dual channel Fast SCSI RAID adapter
.It
Adaptec AHA-39160 64bit PCI dual channel Ultra160 Wide LVD SCSI adapter
.It
Adaptec AHA-4944UW PCI quad channel PCI Ultra Wide Differential SCSI adapter
.It
Other SCSI controllers based on the Adaptec AIC7770, AIC7850,
AIC7860, AIC7870, AIC7880, AIC7890, AIC7891, AIC7892, AIC7895,
AIC7896, AIC7897 and AIC7899 SCSI host adapter chips.
.El
.Sh SCSI CONTROL BLOCKS (SCBs)
Every transaction sent to a device on the SCSI bus is assigned a
.Sq SCSI Control Block
(SCB).
The SCB contains all of the information required by the controller
to process a transaction.
The chip feature table lists the number of SCBs that can be stored
in on-chip memory.
All chips with model numbers greater than or equal to 7870 allow
for the on chip SCB space to be augmented with external SRAM up to
a maximum of 255 SCBs.
Very few Adaptec controller configurations have external SRAM.
.Pp
If external SRAM is not available, SCBs are a limited resource.
Using the SCBs in a straight forward manner would only allow the driver to
handle as many concurrent transactions as there are physical SCBs.
To fully use the SCSI bus and the devices on it,
requires much more concurrency.
The solution to this problem is
.Em SCB Paging ,
a concept similar to memory paging.
SCB paging takes advantage of the fact that devices usually disconnect
from the SCSI bus for long periods of time without talking to the
controller.
The SCBs for disconnected transactions are only of use to the
controller when the transfer is resumed.
When the host queues another transaction for the controller to
execute, the controller firmware will use a free SCB if one is
available.
Otherwise, the state of the most recently disconnected (and therefore
most likely to stay disconnected) SCB is saved, via DMA, to host
memory, and the local SCB reused to start the new transaction.
This allows the controller to queue up to
255 transactions regardless of the amount of SCB space.
Since the local SCB space serves as a cache for disconnected
transactions, the more SCB space available, the less host bus
traffic consumed saving and restoring SCB data.
.Sh SEE ALSO
.Xr aha 4 ,
.Xr ahb 4 ,
.Xr ahd 4 ,
.Xr cd 4 ,
.Xr ch 4 ,
.Xr intro 4 ,
.Xr scsi 4 ,
.Xr sd 4 ,
.Xr st 4
.Sh HISTORY
The
.Nm
driver appeared in
.Fx 2.0
and
.Nx 1.1 .
.Sh AUTHORS
The
.Nm
driver, the AIC7xxx sequencer-code assembler,
and the firmware running on the aic7xxx chips was written by
.An Justin T. Gibbs .
.Nx
porting is done by Stefan Grefen, Charles M. Hannum,
Michael Graff, Jason R. Thorpe, Pete Bentley,
Frank van der Linden and Noriyuki Soda.
.Sh BUGS
Some Quantum drives (at least the Empire 2100 and 1080s) will not run on an
AIC7870 Rev B in synchronous mode at 10MHz.
Controllers with this problem have a
42 MHz clock crystal on them and run slightly above 10MHz.
This confuses the drive and hangs the bus.
Setting a maximum synchronous negotiation rate of 8MHz in the SCSI-Select
utility will allow normal operation.
.Pp
.\" Although the Ultra2 and Ultra160 products have sufficient instruction
.\" ram space to support both the initiator and target roles concurrently,
.\" this configuration is disabled in favor of allowing the target role
.\" to respond on multiple target ids.
.\" A method for configuring dual
.\" role mode should be provided.
.\" .Pp
.\" Tagged Queuing is not supported in target mode.
.\" .Pp
.\" Reselection in target mode fails to function correctly on all high
.\" voltage differential boards as shipped by Adaptec.
.\" Information on
.\" how to modify HVD board to work correctly in target mode is available
.\" from Adaptec.
Target mode is not supported on
.Nx
version of this driver.