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				.\" Copyright (c) 2016 John H. Baldwin <jhb@FreeBSD.org>
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				.Dd May 20, 2016
				.Dt BUS_MAP_RESOURCE 9
				.Os
				.Sh NAME
				.Nm bus_map_resource , bus_unmap_resource , resource_init_map_request
				.Nd map or unmap an active resource
				.Sh SYNOPSIS
				.In sys/param.h
				.In sys/bus.h
				.Pp
				.In machine/bus.h
				.In sys/rman.h
				.In machine/resource.h
				.Ft int
				.Fo bus_map_resource
				.Fa "device_t dev" "int type" "struct resource *r"
				.Fa "struct resource_map_request args" "struct resource_map map"
				.Fc
				.Ft int
				.Fo bus_unmap_resource
				.Fa "device_t dev" "int type" "struct resource r" "struct resource_map map"
				.Fc
				.Ft void
				.Fn resource_init_map_request "struct resource_map_request *args"
				.Sh DESCRIPTION
				These functions create or destroy a mapping of a previously activated
				resource.
				Mappings permit CPU access to the resource via the
				.Xr bus_space 9
				API.
				.Pp
				The arguments are as follows:
				.Bl -tag -width indent
				.It Fa dev
				The device that owns the resource.
				.It Fa type
				The type of resource to map.
				It is one of:
				.Pp
				.Bl -tag -width ".Dv SYS_RES_MEMORY" -compact
				.It Dv SYS_RES_IOPORT
				for I/O ports
				.It Dv SYS_RES_MEMORY
				for I/O memory
				.El
				.It Fa r
				A pointer to the
				.Vt "struct resource"
				returned by
				.Xr bus_alloc_resource 9 .
				.It Fa args
				A set of optional properties to apply when creating a mapping.
				This argument can be set to
				.Dv NULL
				to request a mapping of the entire resource with the default properties.
				.It Fa map
				The resource mapping to create or destroy.
				.El
				.Ss Resource Mappings
				Resource mappings are described by a
				.Vt "struct resource_map"
				object.
				This structure contains a
				.Xr bus_space 9
				tag and handle in the
				.Va r_bustag
				and
				.Va r_bushandle
				members that can be used for CPU access to the mapping.
				The structure also contains a
				.Va r_vaddr
				member which contains the virtual address of the mapping if one exists.
				.Pp
				The wrapper API for
				.Vt "struct resource"
				objects described in
				.Xr bus_activate_resource 9
				can also be used with
				.Vt "struct resource_map" .
				For example,
				a pointer to a mapping object can be passed as the first argument to
				.Fn bus_read_4 .
				This wrapper API is preferred over using the
				.Va r_bustag
				and
				.Va r_bushandle
				members directly.
				.Ss Optional Mapping Properties
				The
				.Vt "struct resource_map_request"
				object passed in
				.Fa args
				can be used to specify optional properties of a mapping.
				The structure must be initialized by invoking
				.Fn resource_init_map_request .
				Properties are then specified by setting one or more of these members:
				.Bl -tag -width indent
				.It Va offset , length
				These two members specify a region of the resource to map.
				By default a mapping is created for the entire resource.
				The
				.Va offset
				is relative to the start of the resource.
				.It Va memattr
				Specifies a memory attribute to use when mapping the resource.
				By default memory mappings use the
				.Dv VM_MEMATTR_UNCACHEABLE
				attribute.
				.El
				.Sh EXAMPLES
				This maps a PCI memory BAR with the write-combining memory attribute and
				reads the first 32-bit word:
				.Bd -literal
				struct resource *r;
				struct resource_map map;
				struct resource_map_args args;
				uint32_t val;
				int rid;

				rid = PCIR_BAR(0);
				r = bus_alloc_resource_any(dev, SYS_RES_MEMORY, &rid, RF_ACTIVE \|
				RF_UNMAPPED);
				resource_init_map_request(&args);
				args.memattr = VM_MEMATTR_WRITE_COMBINING;
				bus_map_resource(dev, SYS_RES_MEMORY, r, &args, &map);
				val = bus_read_4(&map, 0);
				.Ed
				.Pp
				.Sh RETURN VALUES
				Zero is returned on success, otherwise an error is returned.
				.Sh SEE ALSO
				.Xr bus_activate_resource 9 ,
				.Xr bus_alloc_resource 9 ,
				.Xr bus_space 9 ,
				.Xr device 9 ,
				.Xr driver 9
				.Sh AUTHORS
				This manual page was written by
				.An John Baldwin Aq Mt jhb@FreeBSD.org .