209 lines
6.6 KiB
Groff
209 lines
6.6 KiB
Groff
.\" $NetBSD: pci_intr.9,v 1.27 2020/08/27 14:14:00 fcambus Exp $
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.\"
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.\" Copyright (c) 2000 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 Bill Sommerfeld
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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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.\"
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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 September 20, 2018
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.Dt PCI_INTR 9
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.Os
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.Sh NAME
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.Nm pci_intr ,
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.Nm pci_intr_map ,
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.Nm pci_intr_string ,
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.Nm pci_intr_evcnt ,
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.Nm pci_intr_establish ,
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.Nm pci_intr_establish_xname ,
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.Nm pci_intr_disestablish ,
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.Nm pci_intr_setattr
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.Nd PCI bus interrupt manipulation functions
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.Sh SYNOPSIS
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.In dev/pci/pcivar.h
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.Ft int
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.Fn pci_intr_map "const struct pci_attach_args *pa" "pci_intr_handle_t *ih"
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.Ft const char *
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.Fn pci_intr_string "pci_chipset_tag_t pc" "pci_intr_handle_t ih" "char *buf" "size_t len"
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.Ft const struct evcnt *
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.Fn pci_intr_evcnt "pci_chipset_tag_t pc" "pci_intr_handle_t ih"
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.Ft void *
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.Fn pci_intr_establish "pci_chipset_tag_t pc" "pci_intr_handle_t ih" \
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"int ipl" "int (*intrhand)(void *)" "void *intrarg"
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.Ft void *
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.Fn pci_intr_establish_xname "pci_chipset_tag_t pc" "pci_intr_handle_t ih" \
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"int ipl" "int (*intrhand)(void *)" "void *intrarg" "const char *xname"
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.Ft void
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.Fn pci_intr_disestablish "pci_chipset_tag_t pc" "void *ih"
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.Ft int
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.Fn pci_intr_setattr "pci_chipset_tag_t pc" "pci_intr_handle_t *ih" "int attr" "uint64_t data"
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.Sh DESCRIPTION
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The
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.Nm
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functions exist to allow device drivers machine-independent access to
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PCI bus interrupts.
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The functions described in this page are typically declared in a port's
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.In machine/pci_machdep.h
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header file; however, drivers should generally include
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.In dev/pci/pcivar.h
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to get other PCI-specific declarations as well.
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.Pp
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Each driver has an
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.Fn attach
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function which has a bus-specific
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.Ft attach_args
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structure.
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Each driver for a PCI device is passed a pointer to an object of type
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.Ft struct pci_attach_args
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which contains, among other things, information about the location
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of the device in the PCI bus topology sufficient to allow interrupts
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from the device to be handled.
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.Pp
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If a driver wishes to establish an interrupt handler for the device,
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it should pass the
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.Ft struct pci_attach_args *
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to the
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.Fn pci_intr_map
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function, which returns zero on success, and nonzero on failure.
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The function sets the
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.Ft pci_intr_handle_t
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pointed at by its second argument to a machine-dependent value which
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identifies a particular interrupt source.
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.Pp
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If the driver wishes to refer to the interrupt source in an attach or
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error message, it should use the value returned by
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.Fn pci_intr_string .
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The buffer passed to
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.Fn pci_intr_string
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should be at least
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.Dv PCI_INTRSTR_LEN
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bytes.
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.Pp
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Subsequently, when the driver is prepared to receive interrupts, it
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should call
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.Fn pci_intr_establish
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to actually establish the handler; when the device interrupts,
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.Fa intrhand
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will be called with a single argument
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.Fa intrarg ,
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and will run at the interrupt priority level
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.Fa ipl .
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.Pp
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The return value of
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.Fn pci_intr_establish
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may be saved and passed to
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.Fn pci_intr_disestablish
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to disable the interrupt handler
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when the driver is no longer interested in interrupts from the device.
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.Pp
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.Fn pci_intr_establish_xname
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is almost the same as
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.Fn pci_intr_establish .
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The difference is only
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.Fa xname
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which is used by
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.Xr intrctl 8
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to show the device name(s) of the interrupt id.
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.Pp
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The
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.Fn pci_intr_setattr
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function sets an attribute
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.Fa attr
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of the interrupt handler to
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.Fa data .
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Currently, only the following attribute is supported:
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.Bl -tag -width PCI_INTR_MPSAFE
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.It Dv PCI_INTR_MPSAFE
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If this attribute is set to
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.Dv true ,
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it specifies that the interrupt handler is multiprocessor safe and works its
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own locking; otherwise the kernel lock will be held for the call to the
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interrupt handler.
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The default is
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.Dv false .
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.El
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.Pp
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The
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.Fn pci_intr_setattr
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function returns zero on success, and nonzero on failure.
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.Pp
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The
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.Fn pci_intr_evcnt
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function should return an evcnt structure pointer or
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.Dv NULL
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if there is no evcnt associated with this interrupt.
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See
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.Xr evcnt 9
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for more details.
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.Ss PORTING
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A port's implementation of
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.Fn pci_intr_map
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may use the following members of
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.Ft struct pci_attach_args
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to determine how the device's interrupts are routed.
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.Bd -literal
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pci_chipset_tag_t pa_pc;
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pcitag_t pa_tag;
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pcitag_t pa_intrtag; /* intr. appears to come from here */
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pci_intr_pin_t pa_intrpin; /* intr. appears on this pin */
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pci_intr_line_t pa_intrline; /* intr. routing information */
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pci_intr_pin_t pa_rawintrpin; /* unswizzled pin */
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.Ed
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.Pp
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PCI-PCI
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bridges swizzle (permute) interrupt wiring.
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Depending on implementation details, it may be more convenient to use
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either original or the swizzled interrupt parameters.
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The original device tag and interrupt pin can be found in
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.Ft pa_tag
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and
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.Ft pa_rawintrpin
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respectively, while the swizzled tag and pin can be found in
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.Ft pa_intrtag
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and
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.Ft pa_intrpin .
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.Pp
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When a device is attached to a primary bus, both pairs of fields
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contain the same values.
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When a device is found behind one or more pci-pci bridges,
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.Ft pa_intrpin
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contains the
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.Dq swizzled
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interrupt pin number, while
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.Ft pa_rawintrpin
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contains the original interrupt pin;
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.Ft pa_tag
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contains the PCI tag of the device itself, and
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.Ft pa_intrtag
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contains the PCI tag of the uppermost bridge device.
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.Sh SEE ALSO
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.Xr evcnt 9 ,
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.Xr pci 9 ,
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.Xr pci_msi 9
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.Sh HISTORY
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.Fn pci_intr_establish_xname
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was added in
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.Nx 8.0
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as part of MSI/MSI-X support.
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