208 lines
8.4 KiB
ReStructuredText
208 lines
8.4 KiB
ReStructuredText
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Linux and parallel port IDE devices
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===================================
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PARIDE v1.03 (c) 1997-8 Grant Guenther <grant@torque.net>
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PATA_PARPORT (c) 2023 Ondrej Zary
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1. Introduction
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===============
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Owing to the simplicity and near universality of the parallel port interface
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to personal computers, many external devices such as portable hard-disk,
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CD-ROM, LS-120 and tape drives use the parallel port to connect to their
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host computer. While some devices (notably scanners) use ad-hoc methods
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to pass commands and data through the parallel port interface, most
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external devices are actually identical to an internal model, but with
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a parallel-port adapter chip added in. Some of the original parallel port
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adapters were little more than mechanisms for multiplexing a SCSI bus.
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(The Iomega PPA-3 adapter used in the ZIP drives is an example of this
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approach). Most current designs, however, take a different approach.
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The adapter chip reproduces a small ISA or IDE bus in the external device
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and the communication protocol provides operations for reading and writing
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device registers, as well as data block transfer functions. Sometimes,
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the device being addressed via the parallel cable is a standard SCSI
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controller like an NCR 5380. The "ditto" family of external tape
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drives use the ISA replicator to interface a floppy disk controller,
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which is then connected to a floppy-tape mechanism. The vast majority
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of external parallel port devices, however, are now based on standard
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IDE type devices, which require no intermediate controller. If one
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were to open up a parallel port CD-ROM drive, for instance, one would
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find a standard ATAPI CD-ROM drive, a power supply, and a single adapter
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that interconnected a standard PC parallel port cable and a standard
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IDE cable. It is usually possible to exchange the CD-ROM device with
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any other device using the IDE interface.
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The document describes the support in Linux for parallel port IDE
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devices. It does not cover parallel port SCSI devices, "ditto" tape
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drives or scanners. Many different devices are supported by the
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parallel port IDE subsystem, including:
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- MicroSolutions backpack CD-ROM
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- MicroSolutions backpack PD/CD
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- MicroSolutions backpack hard-drives
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- MicroSolutions backpack 8000t tape drive
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- SyQuest EZ-135, EZ-230 & SparQ drives
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- Avatar Shark
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- Imation Superdisk LS-120
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- Maxell Superdisk LS-120
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- FreeCom Power CD
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- Hewlett-Packard 5GB and 8GB tape drives
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- Hewlett-Packard 7100 and 7200 CD-RW drives
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as well as most of the clone and no-name products on the market.
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To support such a wide range of devices, pata_parport is actually structured
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in two parts. There is a base pata_parport module which provides an interface
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to kernel libata subsystem, registry and some common methods for accessing
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the parallel ports.
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The second component is a set of low-level protocol drivers for each of the
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parallel port IDE adapter chips. Thanks to the interest and encouragement of
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Linux users from many parts of the world, support is available for almost all
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known adapter protocols:
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==== ====================================== ====
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aten ATEN EH-100 (HK)
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bpck Microsolutions backpack (US)
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comm DataStor (old-type) "commuter" adapter (TW)
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dstr DataStor EP-2000 (TW)
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epat Shuttle EPAT (UK)
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epia Shuttle EPIA (UK)
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fit2 FIT TD-2000 (US)
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fit3 FIT TD-3000 (US)
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friq Freecom IQ cable (DE)
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frpw Freecom Power (DE)
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kbic KingByte KBIC-951A and KBIC-971A (TW)
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ktti KT Technology PHd adapter (SG)
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on20 OnSpec 90c20 (US)
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on26 OnSpec 90c26 (US)
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==== ====================================== ====
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2. Using pata_parport subsystem
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===============================
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While configuring the Linux kernel, you may choose either to build
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the pata_parport drivers into your kernel, or to build them as modules.
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In either case, you will need to select "Parallel port IDE device support"
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and at least one of the parallel port communication protocols.
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If you do not know what kind of parallel port adapter is used in your drive,
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you could begin by checking the file names and any text files on your DOS
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installation floppy. Alternatively, you can look at the markings on
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the adapter chip itself. That's usually sufficient to identify the
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correct device.
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You can actually select all the protocol modules, and allow the pata_parport
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subsystem to try them all for you.
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For the "brand-name" products listed above, here are the protocol
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and high-level drivers that you would use:
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================ ============ ========
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Manufacturer Model Protocol
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================ ============ ========
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MicroSolutions CD-ROM bpck
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MicroSolutions PD drive bpck
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MicroSolutions hard-drive bpck
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MicroSolutions 8000t tape bpck
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SyQuest EZ, SparQ epat
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Imation Superdisk epat
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Maxell Superdisk friq
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Avatar Shark epat
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FreeCom CD-ROM frpw
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Hewlett-Packard 5GB Tape epat
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Hewlett-Packard 7200e (CD) epat
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Hewlett-Packard 7200e (CD-R) epat
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================ ============ ========
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All parports and all protocol drivers are probed automatically unless probe=0
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parameter is used. So just "modprobe epat" is enough for a Imation SuperDisk
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drive to work.
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Manual device creation::
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# echo "port protocol mode unit delay" >/sys/bus/pata_parport/new_device
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where:
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======== ================================================
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port parport name (or "auto" for all parports)
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protocol protocol name (or "auto" for all protocols)
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mode mode number (protocol-specific) or -1 for probe
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unit unit number (for backpack only, see below)
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delay I/O delay (see troubleshooting section below)
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======== ================================================
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If you happen to be using a MicroSolutions backpack device, you will
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also need to know the unit ID number for each drive. This is usually
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the last two digits of the drive's serial number (but read MicroSolutions'
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documentation about this).
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If you omit the parameters from the end, defaults will be used, e.g.:
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Probe all parports with all protocols::
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# echo auto >/sys/bus/pata_parport/new_device
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Probe parport0 using protocol epat and mode 4 (EPP-16)::
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# echo "parport0 epat 4" >/sys/bus/pata_parport/new_device
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Probe parport0 using all protocols::
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# echo "parport0 auto" >/sys/bus/pata_parport/new_device
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Probe all parports using protoocol epat::
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# echo "auto epat" >/sys/bus/pata_parport/new_device
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Deleting devices::
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# echo pata_parport.0 >/sys/bus/pata_parport/delete_device
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3. Troubleshooting
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==================
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3.1 Use EPP mode if you can
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----------------------------
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The most common problems that people report with the pata_parport drivers
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concern the parallel port CMOS settings. At this time, none of the
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protocol modules support ECP mode, or any ECP combination modes.
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If you are able to do so, please set your parallel port into EPP mode
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using your CMOS setup procedure.
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3.2 Check the port delay
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-------------------------
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Some parallel ports cannot reliably transfer data at full speed. To
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offset the errors, the protocol modules introduce a "port
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delay" between each access to the i/o ports. Each protocol sets
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a default value for this delay. In most cases, the user can override
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the default and set it to 0 - resulting in somewhat higher transfer
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rates. In some rare cases (especially with older 486 systems) the
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default delays are not long enough. if you experience corrupt data
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transfers, or unexpected failures, you may wish to increase the
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port delay.
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3.3 Some drives need a printer reset
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-------------------------------------
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There appear to be a number of "noname" external drives on the market
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that do not always power up correctly. We have noticed this with some
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drives based on OnSpec and older Freecom adapters. In these rare cases,
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the adapter can often be reinitialised by issuing a "printer reset" on
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the parallel port. As the reset operation is potentially disruptive in
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multiple device environments, the pata_parport drivers will not do it
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automatically. You can however, force a printer reset by doing::
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insmod lp reset=1
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rmmod lp
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If you have one of these marginal cases, you should probably build
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your pata_parport drivers as modules, and arrange to do the printer reset
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before loading the pata_parport drivers.
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