b4b2ae5652
Add a pair of bus methods that can be used to "map" resources for direct CPU access using bus_space(9). bus_map_resource() creates a mapping and bus_unmap_resource() releases a previously created mapping. Mappings are described by 'struct resource_map' object. Pointers to these objects can be passed as the first argument to the bus_space wrapper API used for bus resources. Drivers that wish to map all of a resource using default settings (for example, using uncacheable memory attributes) do not need to change. However, drivers that wish to use non-default settings can now do so without jumping through hoops. First, an RF_UNMAPPED flag is added to request that a resource is not implicitly mapped with the default settings when it is activated. This permits other activation steps (such as enabling I/O or memory decoding in a device's PCI command register) to be taken without creating a mapping. Right now the AGP drivers don't set RF_ACTIVE to avoid using up a large amount of KVA to map the AGP aperture on 32-bit platforms. Once RF_UNMAPPED is supported on all platforms that support AGP this can be changed to using RF_UNMAPPED with RF_ACTIVE instead. Second, bus_map_resource accepts an optional structure that defines additional settings for a given mapping. For example, a driver can now request to map only a subset of a resource instead of the entire range. The AGP driver could also use this to only map the first page of the aperture (IIRC, it calls pmap_mapdev() directly to map the first page currently). I will also eventually change the PCI-PCI bridge driver to request mappings of the subset of the I/O window resource on its parent side to create mappings for child devices rather than passing child resources directly up to nexus to be mapped. This also permits bridges that do address translation to request suitable mappings from a resource on the "upper" side of the bus when mapping resources on the "lower" side of the bus. Another attribute that can be specified is an alternate memory attribute for memory-mapped resources. This can be used to request a Write-Combining mapping of a PCI BAR in an MI fashion. (Currently the drivers that do this call pmap_change_attr() directly for x86 only.) Note that this commit only adds the MI framework. Each platform needs to add support for handling RF_UNMAPPED and thew new bus_map/unmap_resource methods. Generally speaking, any drivers that are calling rman_set_bustag() and rman_set_bushandle() need to be updated. Discussed on: arch Reviewed by: cem Differential Revision: https://reviews.freebsd.org/D5237
209 lines
5.8 KiB
Groff
209 lines
5.8 KiB
Groff
.\" -*- nroff -*-
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.\"
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.\" Copyright (c) 2000 Alexander Langer
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.\"
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.\" All rights reserved.
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.\"
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.\" This program is free software.
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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 DEVELOPERS ``AS IS'' AND ANY EXPRESS OR
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.\" IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
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.\" OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
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.\" IN NO EVENT SHALL THE DEVELOPERS BE LIABLE FOR ANY DIRECT, INDIRECT,
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.\" INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
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.\" NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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.\" DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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.\" THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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.\" (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
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.\" THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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.\"
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.\" $FreeBSD$
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.\"
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.Dd May 20, 2016
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.Dt BUS_ALLOC_RESOURCE 9
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.Os
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.Sh NAME
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.Nm bus_alloc_resource ,
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.Nm bus_alloc_resource_any
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.Nm bus_alloc_resource_anywhere
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.Nd allocate resources from a parent bus
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.Sh SYNOPSIS
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.In sys/param.h
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.In sys/bus.h
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.Pp
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.In machine/bus.h
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.In sys/rman.h
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.In machine/resource.h
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.Ft struct resource *
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.Fo bus_alloc_resource
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.Fa "device_t dev" "int type" "int *rid" "rman_res_t start" "rman_res_t end"
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.Fa "rman_res_t count" "u_int flags"
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.Fc
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.Ft struct resource *
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.Fn bus_alloc_resource_any "device_t dev" "int type" "int *rid" "u_int flags"
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.Ft struct resource *
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.Fo bus_alloc_resource_anywhere
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.Fa "device_t dev" "int type" "int *rid" "rman_res_t count" "u_int flags"
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.Fc
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.Sh DESCRIPTION
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This is an easy interface to the resource-management functions.
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It hides the indirection through the parent's method table.
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This function generally should be called in attach, but (except in some
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rare cases) never earlier.
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.Pp
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The
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.Fn bus_alloc_resource_any
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and
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.Fn bus_alloc_resource_anywhere
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functions are convenience wrappers for
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.Fn bus_alloc_resource .
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.Fn bus_alloc_resource_any
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sets
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.Fa start ,
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.Fa end ,
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and
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.Fa count
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to the default resource (see description of
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.Fa start
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below).
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.Fn bus_alloc_resource_anywhere
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sets
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.Fa start
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and
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.Fa end
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to the default resource and uses the provided
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.Fa count
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argument.
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.Pp
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The arguments are as follows:
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.Bl -item
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.It
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.Fa dev
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is the device that requests ownership of the resource.
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Before allocation, the resource is owned by the parent bus.
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.It
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.Fa type
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is the type of resource you want to allocate.
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It is one of:
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.Bl -tag -width SYS_RES_MEMORY
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.It Dv PCI_RES_BUS
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for PCI bus numbers
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.It Dv SYS_RES_IRQ
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for IRQs
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.It Dv SYS_RES_DRQ
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for ISA DMA lines
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.It Dv SYS_RES_IOPORT
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for I/O ports
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.It Dv SYS_RES_MEMORY
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for I/O memory
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.El
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.It
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.Fa rid
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points to a bus specific handle that identifies the resource being allocated.
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For ISA this is an index into an array of resources that have been setup
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for this device by either the PnP mechanism, or via the hints mechanism.
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For PCCARD, this is an index into the array of resources described by the PC Card's
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CIS entry.
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For PCI, the offset into PCI config space which has the BAR to use to access
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the resource.
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The bus methods are free to change the RIDs that they are given as a parameter.
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You must not depend on the value you gave it earlier.
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.It
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.Fa start
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and
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.Fa end
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are the start/end addresses of the resource.
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If you specify values of 0ul for
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.Fa start
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and ~0ul for
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.Fa end
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and 1 for
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.Fa count ,
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the default values for the bus are calculated.
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.It
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.Fa count
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is the size of the resource.
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For example, the size of an I/O port is usually 1 byte (but some devices
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override this).
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If you specified the default values for
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.Fa start
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and
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.Fa end ,
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then the default value of the bus is used if
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.Fa count
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is smaller than the default value and
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.Fa count
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is used, if it is bigger than the default value.
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.It
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.Fa flags
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sets the flags for the resource.
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You can set one or more of these flags:
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.Bl -tag -width RF_SHAREABLE
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.It Dv RF_ALLOCATED
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resource has been reserved.
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The resource still needs to be activated with
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.Xr bus_activate_resource 9 .
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.It Dv RF_ACTIVE
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activate resource atomically.
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.It Dv RF_PREFETCHABLE
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resource is prefetchable.
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.It Dv RF_SHAREABLE
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resource permits contemporaneous sharing.
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It should always be set unless you know that the resource cannot be shared.
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It is the bus driver's task to filter out the flag if the bus does not
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support sharing.
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For example,
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.Xr pccard 4
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cannot share IRQs while
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.Xr cardbus 4
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can.
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.It Dv RF_UNMAPPED
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do not establish implicit mapping when activated via
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.Xr bus_activate_resource 9 .
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.El
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.El
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.Sh RETURN VALUES
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A pointer to
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.Va struct resource
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is returned on success, a null pointer otherwise.
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.Sh EXAMPLES
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This is some example code that allocates a 32 byte I/O port range and an IRQ.
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The values of
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.Va portid
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and
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.Va irqid
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should be saved in the softc of the device after these calls.
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.Bd -literal
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struct resource *portres, *irqres;
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int portid, irqid;
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portid = 0;
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irqid = 0;
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portres = bus_alloc_resource(dev, SYS_RES_IOPORT, &portid,
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0ul, ~0ul, 32, RF_ACTIVE);
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irqres = bus_alloc_resource_any(dev, SYS_RES_IRQ, &irqid,
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RF_ACTIVE | RF_SHAREABLE);
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.Ed
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.Sh SEE ALSO
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.Xr bus_activate_resource 9 ,
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.Xr bus_adjust_resource 9 ,
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.Xr bus_map_resource 9 ,
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.Xr bus_release_resource 9 ,
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.Xr device 9 ,
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.Xr driver 9
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.Sh AUTHORS
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.An -nosplit
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This manual page was written by
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.An Alexander Langer Aq Mt alex@big.endian.de
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with parts by
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.An Warner Losh Aq Mt imp@FreeBSD.org .
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