207 lines
7.3 KiB
Groff
207 lines
7.3 KiB
Groff
.\" $NetBSD: mca.9,v 1.5 2002/10/14 13:43:27 wiz Exp $
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.\"
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.\" Copyright (c) 2001 The NetBSD Foundation, Inc.
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.\" All rights reserved.
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.\"
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.\" This code is derived from software contributed to The NetBSD Foundation
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.\" by Gregory McGarry.
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.\"
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.\" Redistribution and use in source and binary forms, with or without
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.\" modification, are permitted provided that the following conditions
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.\" are met:
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.\" 1. Redistributions of source code must retain the above copyright
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.\" notice, this list of conditions and the following disclaimer.
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.\" 2. Redistributions in binary form must reproduce the above copyright
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.\" notice, this list of conditions and the following disclaimer in the
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.\" documentation and/or other materials provided with the distribution.
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.\" 3. All advertising materials mentioning features or use of this software
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.\" must display the following acknowledgement:
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.\" This product includes software developed by the NetBSD
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.\" Foundation, Inc. and its contributors.
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.\" 4. Neither the name of The NetBSD Foundation nor the names of its
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.\" contributors may be used to endorse or promote products derived
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.\" from this software without specific prior written permission.
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.\"
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.\" THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
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.\" ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
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.\" TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
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.\" PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
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.\" BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
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.\" CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
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.\" SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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.\" INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
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.\" CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
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.\" ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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.\" POSSIBILITY OF SUCH DAMAGE.
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.\"
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.Dd October 7, 2001
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.Dt MCA 9
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.Os
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.Sh NAME
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.Nm MCA ,
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.Nm mca_intr_establish ,
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.Nm mca_intr_disestablish ,
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.Nm mca_intr_evcnt ,
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.Nm mca_conf_read ,
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.Nm mca_conf_write
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.Nd MicroChannel Architecture bus
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.Sh SYNOPSIS
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.Fd #include \*[Lt]machine/bus.h\*[Gt]
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.Fd #include \*[Lt]dev/mca/mcavar.h\*[Gt]
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.Fd #include \*[Lt]dev/mca/mcadevs.h\*[Gt]
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.Ft void *
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.Fn mca_intr_establish "mca_chipset_tag_t mc" "mca_intr_handle_t hdl" \
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"int level" "int (*handler)(void *)" "void *arg"
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.Ft void
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.Fn mca_intr_disestablish "mca_chipset_tag_t mc" "mca_intr_handle_t hdl"
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.Ft const struct evcnt *
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.Fn mca_intr_evcnt "mca_chipset_tag_t mc" "mca_intr_handle_t hdl"
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.Ft int
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.Fn mca_conf_read "mca_chipset_tag_t mc" "int slot" "int reg"
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.Ft void
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.Fn mca_conf_write "mca_chipset_tag_t mc" "int slot" "int reg" \
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"int data"
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.Sh DESCRIPTION
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The
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.Nm
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device provides support for IBM's MicroChannel Architecture bus found
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on IBM PS/2 systems and selected workstations.
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It was designed as a replacement bus for the ISA bus found on IBM's
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older machines.
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However, the bus specifications were only available under license, so
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MCA did not achieve widespread acceptance in the industry.
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.Pp
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Being a replacement for the ISA bus, the MCA bus does share some
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similar aspects with the ISA bus.
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Some MCA devices can be detected via the usual ISA-style probing.
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However, most device detection is done through the Programmable Option
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Select (POS) registers.
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These registers provide a window into a device to determine device-specific
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properties and configuration.
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The configuration of devices and their POS registers is performed using
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IBM's system configuration software.
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.Pp
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The MCA bus uses level-triggered interrupts while the ISA bus uses
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edge-triggered interrupts.
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Level triggered interrupts have the advantage that they can be shared
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among multiple device.
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Therefore, most MCA-specific devices should be coded with shared
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interrupts in mind.
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.Sh DATA TYPES
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Drivers for devices attached to the MCA bus will make use of the
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following data types:
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.Bl -tag -width compact
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.It Fa mca_chipset_tag_t
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Chipset tag for the MCA bus.
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.It Fa mca_intr_handle_t
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The opaque handle describing an established interrupt handler.
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.It Fa struct mca_attach_args
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A structure use to inform the driver of MCA bus properties.
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It contains the following members:
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.Bd -literal
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bus_space_tag_t ma_iot; /* MCA I/O space tag */
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bus_space_tag_t ma_memt; /* MCA mem space tag */
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bus_dma_tag_t ma_dmat; /* MCA DMA tag */
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int ma_slot; /* MCA slot number */
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int ma_pos[8]; /* MCA POS values */
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int ma_id; /* MCA device */
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.Ed
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.El
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.Sh FUNCTIONS
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.Bl -tag -width compact
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.It Fn mca_intr_establish "mc" "hdl" "level" "handler" "arg"
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Establish a MCA interrupt handler on the MCA bus specified by
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.Fa mc
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for the interrupt described completely by
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.Fa hdl .
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The priority of the interrupt is specified by
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.Fa level .
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When the interrupt occurs the function
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.Fa handler
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is called with argument
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.Fa arg .
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.It Fn mca_intr_disestablish "mc" "hdl"
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Dis-establish the interrupt handler on the MCA bus specified by
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.Fa mc
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for the interrupt described completely
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.Fa hdl .
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.It Fn mca_intr_evcnt "mc" "hdl"
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Do interrupt event counting on the MCA bus specified by
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.Fa mc
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for the event described completely by
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.Fa hdl .
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.It Fn mca_conf_read "mc" "slot" "reg"
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Read the POS register
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.Fa reg
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for the device in slot
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.Fa slot
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on the MCA bus specified by
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.Fa mc .
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.It Fn mca_conf_write "mc" "slot" "reg" "data"
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Write data
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.Fa data
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to the POS register
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.Fa reg
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for the device in slot
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.Fa slot
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on the MCA bus specified by
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.Fa mc .
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.El
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.Sh AUTOCONFIGURATION
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The MCA bus is a direct-connection bus.
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During autoconfiguration, the parent specifies the MCA device ID for the
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found device in the
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.Fa ma_id
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member of the
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.Em mca_attach_args
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structure.
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Drivers should match on the device ID.
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Device capabilities and configuration information should be read from
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device POS registers using
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.Fn mca_conf_read .
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Some important configuration information found in the POS registers
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include the I/O base address, memory base address and interrupt
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number.
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The location of these configurable options with the POS registers are
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device specific.
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.Sh DMA SUPPORT
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The MCA bus supports 32-bit, bidirectional DMA transfers.
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Currently, no machine-independent support for MCA DMA is available.
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.Sh CODE REFERENCES
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This section describes places within the
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.Nx
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source tree where actual code implementing or utilising the
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machine-independent MCA subsystem can be found.
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All pathnames are relative to
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.Pa /usr/src .
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.Pp
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The MCA subsystem itself is implemented within the file
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.Pa sys/dev/mca/mca_subr.c .
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Machine-dependent portions can be found in
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.Pa sys/arch/\*[Lt]arch\*[Gt]/mca/mca_machdep.c .
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The database of known devices exists within the file
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.Fa sys/dev/mca/mcadevs_data.h
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and is generated automatically from the file
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.Pa sys/dev/mca/mcadevs .
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New vendor and product identifiers should be added to this file.
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The database can be regenerated using the Makefile
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.Pa sys/dev/mca/Makefile.mcadevs .
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.Pp
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A good source of information about MCA devices is IBM's system
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configuration disk.
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The disk contains .adf files which describe the location of device
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configuration options in the POS registers.
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.Sh SEE ALSO
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.Xr mca 4 ,
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.Xr autoconf 9 ,
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.Xr bus_dma 9 ,
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.Xr bus_space 9 ,
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.Xr driver 9 ,
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.Xr isa 9
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.Sh BUGS
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The machine-independent
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.Nm
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driver does not currently support DMA.
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MCA devices which require DMA operation currently access the DMA
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capabilities directly.
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