Document bus_space_reserve(9), bus_space_reserve_subregion(9),
bus_space_release(9), bus_space_reservation_map(9), bus_space_reservation_unmap(9), bus_space_reservation_addr(9), bus_space_reservation_size(9), bus_space_handle_is_equal(9).
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dyoung
parent
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9063212b84
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@ -1,4 +1,4 @@
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.\" $NetBSD: bus_space.9,v 1.42 2011/07/01 22:06:19 dyoung Exp $
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.\" $NetBSD: bus_space.9,v 1.43 2011/07/06 18:27:31 dyoung Exp $
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.\"
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.\" Copyright (c) 1997 The NetBSD Foundation, Inc.
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.\" All rights reserved.
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@ -27,7 +27,7 @@
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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 July 1, 2011
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.Dd July 6, 2011
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.Dt BUS_SPACE 9
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.Os
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.Sh NAME
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@ -38,6 +38,7 @@
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.Nm bus_space_copy_region_4 ,
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.Nm bus_space_copy_region_8 ,
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.Nm bus_space_free ,
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.Nm bus_space_handle_is_equal ,
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.Nm bus_space_is_equal ,
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.Nm bus_space_map ,
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.Nm bus_space_mmap ,
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@ -73,6 +74,14 @@
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.Nm bus_space_read_stream_2 ,
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.Nm bus_space_read_stream_4 ,
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.Nm bus_space_read_stream_8 ,
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.Nm bus_space_release ,
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.Nm bus_space_reservation_addr ,
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.Nm bus_space_reservation_init ,
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.Nm bus_space_reservation_size ,
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.Nm bus_space_reservation_map ,
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.Nm bus_space_reservation_unmap ,
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.Nm bus_space_reserve ,
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.Nm bus_space_reserve_subregion ,
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.Nm bus_space_set_region_1 ,
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.Nm bus_space_set_region_2 ,
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.Nm bus_space_set_region_4 ,
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@ -108,7 +117,31 @@
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.Sh SYNOPSIS
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.In sys/bus.h
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.Ft bool
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.Fn bus_space_handle_is_equal "bus_space_tag_t space" \
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"bus_space_handle_t handle1" "bus_space_handle_t handle2"
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.Ft bool
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.Fn bus_space_is_equal "bus_space_tag_t space1" "bus_space_tag_t space2"
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.Ft void
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.Fn bus_space_release "bus_space_tag_t t" "bus_space_reservation_t *bsr"
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.Ft int
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.Fn bus_space_reserve "bus_space_tag_t t" "bus_addr_t bpa" "bus_size_t size" \
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"int flags" "bus_space_reservation_t *bsrp"
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.Ft int
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.Fn bus_space_reserve_subregion "bus_space_tag_t t" \
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"bus_addr_t reg_start" "bus_addr_t reg_end" \
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"bus_size_t size" "bus_size_t alignment" "bus_size_t boundary" \
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"int flags" "bus_space_reservation_t *bsrp"
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.Ft void
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.Fn bus_space_reservation_init "bus_space_reservation_t *bsr" \
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"bus_addr_t addr" "bus_size_t size"
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.Ft bus_size_t
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.Fn bus_space_reservation_size "bus_space_reservation_t *bsr"
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.Ft int
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.Fn bus_space_reservation_map "bus_space_tag_t t" \
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"bus_space_reservation_t *bsr" "int flags" "bus_space_handle_t *bshp"
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.Ft void
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.Fn bus_space_reservation_unmap "bus_space_tag_t t" "bus_space_handle_t bsh" \
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"bus_size_t size"
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.Ft int
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.Fn bus_space_map "bus_space_tag_t space" "bus_addr_t address" \
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"bus_size_t size" "int flags" "bus_space_handle_t *handlep"
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@ -544,6 +577,25 @@ type is used to describe a mapping of a range of bus space.
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Its contents are machine-dependent and should be considered opaque by
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machine-independent code.
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This type is used when performing bus space access operations.
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.It Fa bus_space_reservation_t
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.Pp
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The
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.Fa bus_space_reservation_t
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type is used to describe a range of bus space.
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It logically consists of a
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.Fa bus_addr_t ,
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the first address in the range,
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and a
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.Fa bus_size_t ,
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the length in bytes of the range.
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Machine-independent code creates and interrogates a
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.Fa bus_space_reservation_t
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using a constructor,
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.Fn bus_space_reservation_init ,
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and accessor functions,
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.Fn bus_space_reservation_addr
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and
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.Fn bus_space_reservation_size .
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.El
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.Sh COMPARING BUS SPACE TAGS
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To check whether or not one
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@ -563,7 +615,9 @@ instead.
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Bus space must be mapped before it can be used, and should be
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unmapped when it is no longer needed.
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The
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.Fn bus_space_map
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.Fn bus_space_map ,
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.Fn bus_space_reservation_map ,
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.Fn bus_space_reservation_unmap ,
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and
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.Fn bus_space_unmap
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functions provide these capabilities.
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@ -579,7 +633,7 @@ function allows such subregions to be created.
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.Pp
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The
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.Fn bus_space_map
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function maps the region of bus space named by the
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function exclusively reserves and maps the region of bus space named by the
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.Fa space ,
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.Fa address ,
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and
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@ -666,11 +720,44 @@ ISA memory and I/O spaces).
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Mapped regions may contain areas for which there is no device on the bus.
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If space in those areas is accessed, the results are bus-dependent.
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.Pp
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.It Fn bus_space_reservation_map "space" "bsr" "flags" "handlep"
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.Pp
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The
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.Fn bus_space_reservation_map
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function is similar to
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.Fn bus_space_map but it maps a region of bus space
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that was previously reserved by a call to
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.Fn bus_space_reserve
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or
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.Fn bus_space_reserve_subregion .
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The region is given by the
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.Fa space
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and
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.Fa bsr
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arguments.
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If successful, it returns zero and fills in the bus space handle pointed
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to by
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.Fa handlep
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with the handle that can be used to access the mapped region.
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If unsuccessful, it will return non-zero and leave the bus space handle
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pointed to by
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.Fa handlep
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in an undefined state.
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.Pp
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A region mapped by
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.Fn bus_space_reservation_map
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may only be unmapped by a call to
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.Fn bus_space_reservation_unmap .
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.Pp
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For more details, see the description of
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.Fn bus_space_map .
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.Pp
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.It Fn bus_space_unmap "space" "handle" "size"
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.Pp
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The
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.Fn bus_space_unmap
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function unmaps a region of bus space mapped with
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function unmaps and relinquishes a region of bus space reserved and
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mapped with
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.Fn bus_space_map .
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When unmapping a region, the
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.Fa size
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@ -691,6 +778,26 @@ In that case,
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.Fn bus_space_unmap
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will never return.
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.Pp
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.It Fn bus_space_reservation_unmap "space" "handle" "size"
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.Pp
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The
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.Fn bus_space_reservation_unmap
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function is similar to
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.Fn bus_space_unmap
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but it should be called on handles
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mapped by
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.Fn bus_space_reservation_map
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and only on such handles.
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Unlike
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.Fn bus_space_unmap ,
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.Fn bus_space_reservation_unmap
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does not relinquish exclusive use of the bus space named by
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.Fa handle
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and
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.Fa size ;
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that is the job of
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.Fn bus_space_release .
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.Pp
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.It Fn bus_space_subregion "space" "handle" "offset" "size" "nhandlep"
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.Pp
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The
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@ -785,6 +892,16 @@ The
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.Fa prot
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argument indicates the memory protection requested by the user application
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for the range.
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.Pp
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.It Fn bus_space_handle_is_equal "space" "handle1" "handle2"
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Use
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.Fn bus_space_handle_is_equal to
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check whether or not
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.Fa handle1
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and
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.Fa handle2
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refer to regions starting at the same address in the bus space
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.Fa space .
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.El
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.Sh ALLOCATING AND FREEING BUS SPACE
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Some devices require or allow bus space to be allocated by the operating
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@ -792,10 +909,19 @@ system for device use.
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When the devices no longer need the space, the
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operating system should free it for use by other devices.
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The
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.Fn bus_space_alloc
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.Fn bus_space_alloc ,
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.Fn bus_space_free ,
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.Fn bus_space_reserve ,
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.Fn bus_space_reserve_subregion ,
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and
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.Fn bus_space_free
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.Fn bus_space_release
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functions provide these capabilities.
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The functions
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.Fn bus_space_reserve ,
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.Fn bus_space_reserve_subregion ,
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and
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.Fn bus_space_release
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are not yet available on all architectures.
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.Pp
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.Bl -ohang -compact
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.It Fn bus_space_alloc "space" "reg_start" "reg_end" "size" "alignment" \
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@ -873,6 +999,120 @@ The
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function can be used on handles created by
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.Fn bus_space_alloc .
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.Pp
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.It Fn bus_space_reserve "t" "bpa" "size" "flags" "bsrp"
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.Pp
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The
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.Fn bus_space_reserve
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function reserves, for the caller's exclusive use,
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.Fa size
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bytes starting at the address
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.Fa bpa
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in the space referenced by
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.Fa t .
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.Pp
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.Fn bus_space_reserve
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does
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.Em not
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map the space.
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The caller should use
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.Fn bus_space_reservation_map
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to map the reservation.
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.Fa flags
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contains a hint how the caller may map the reservation, later.
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Whenever possible, callers should pass the same flags to
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.Fn bus_space_reserve
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as they will pass to
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.Fn bus_space_reservation_map
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to map the reservation.
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.Pp
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On success,
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.Fn bus_space_reserve
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records the reservation at
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.Fa bsrp
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and returns 0.
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On failure,
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.Fa bsrp
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is undefined, and
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.Fn bus_space_reserve
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returns a non-zero error code.
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Possible error codes include
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.Bl -tag -width EOPNOTSUPP -offset indent
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.It Dv EOPNOTSUPP
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.Fn bus_space_reserve
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is not supported on this architecture, or
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.Fa flags
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was incompatible with the bus space represented by
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.Fa t .
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.It Dv ENOMEM
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There was not sufficient bus space at
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.Fa bpa
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to satisfy the request.
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.El
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.Pp
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.It Fn bus_space_reserve_subregion "t" "reg_start" "reg_end" \
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"size" "alignment" "boundary" "flags" "bsrp"
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.Pp
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The
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.Fn bus_space_reserve_subregion
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function reserves, for the caller's exclusive use,
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.Fa size
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bytes in the space referenced by
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.Fa t .
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The parameters
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.Fa reg_start ,
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.Fa reg_end ,
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.Fa alignment ,
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.Fa boundary ,
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and
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.Fa flags
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each work alike to the
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.Fn bus_space_alloc
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parameters of the same names.
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.Pp
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On success,
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.Fn bus_space_reserve_subregion
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records the reservation at
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.Fa bsrp
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and returns 0.
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On failure,
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.Fa bsrp
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is undefined, and
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.Fn bus_space_reserve_subregion
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returns a non-zero error code.
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Possible error codes include
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.Bl -tag -width EOPNOTSUPP -offset indent
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.It Dv EOPNOTSUPP
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.Fn bus_space_reserve
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is not supported on this architecture, or
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.Fa flags
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was incompatible with the bus space represented by
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.Fa t .
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.It Dv ENOMEM
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There was not sufficient bus space at
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.Fa bpa
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to satisfy the request.
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.El
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.Pp
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.It Fn bus_space_release "t" "bsr"
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.Pp
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The
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.Fn bus_space_release
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function releases the bus space
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.Fa bsr
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in
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.Fa t
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that was previously reserved by
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.Fn bus_space_reserve
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or
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.Fn bus_space_reserve_subregion .
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.Pp
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If
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.Fn bus_space_release
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is called on a reservation that has been mapped by
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.Fn bus_space_reservation_map
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without subsequently being unmapped, the behavior of the system is
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undefined.
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.Pp
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.It Fn bus_space_free "space" "handle" "size"
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.Pp
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The
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