BUS_MAP_RESOURCE(9)    FreeBSD Kernel Developer's Manual   BUS_MAP_RESOURCE(9)

NAME
     bus_map_resource, bus_unmap_resource, resource_init_map_request - map or
     unmap an active resource

SYNOPSIS
     #include <sys/param.h>
     #include <sys/bus.h>

     #include <machine/bus.h>
     #include <sys/rman.h>
     #include <machine/resource.h>

     int
     bus_map_resource(device_t dev, int type, struct resource *r,
         struct resource_map_request *args, struct resource_map *map);

     int
     bus_unmap_resource(device_t dev, int type, struct resource *r,
         struct resource_map *map);

     void
     resource_init_map_request(struct resource_map_request *args);

DESCRIPTION
     These functions create or destroy a mapping of a previously activated
     resource.  Mappings permit CPU access to the resource via the
     bus_space(9) API.

     The arguments are as follows:

     dev     The device that owns the resource.

     type    The type of resource to map.  It is one of:

             SYS_RES_IOPORT      for I/O ports
             SYS_RES_MEMORY      for I/O memory

     r       A pointer to the struct resource returned by
             bus_alloc_resource(9).

     args    A set of optional properties to apply when creating a mapping.
             This argument can be set to NULL to request a mapping of the
             entire resource with the default properties.

     map     The resource mapping to create or destroy.

   Resource Mappings
     Resource mappings are described by a struct resource_map object.  This
     structure contains a bus_space(9) tag and handle in the r_bustag and
     r_bushandle members that can be used for CPU access to the mapping.  The
     structure also contains a r_vaddr member which contains the virtual
     address of the mapping if one exists.

     The wrapper API for struct resource objects described in
     bus_activate_resource(9) can also be used with struct resource_map.  For
     example, a pointer to a mapping object can be passed as the first
     argument to bus_read_4().  This wrapper API is preferred over using the
     r_bustag and r_bushandle members directly.

   Optional Mapping Properties
     The struct resource_map_request object passed in args can be used to
     specify optional properties of a mapping.  The structure must be
     initialized by invoking resource_init_map_request().  Properties are then
     specified by setting one or more of these members:

     offset, length
             These two members specify a region of the resource to map.  By
             default a mapping is created for the entire resource.  The offset
             is relative to the start of the resource.

     memattr
             Specifies a memory attribute to use when mapping the resource.
             By default memory mappings use the VM_MEMATTR_UNCACHEABLE
             attribute.

RETURN VALUES
     Zero is returned on success, otherwise an error is returned.

EXAMPLES
     This maps a PCI memory BAR with the write-combining memory attribute and
     reads the first 32-bit word:

             struct resource *r;
             struct resource_map map;
             struct resource_map_request req;
             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(&req);
             req.memattr = VM_MEMATTR_WRITE_COMBINING;
             bus_map_resource(dev, SYS_RES_MEMORY, r, &req, &map);
             val = bus_read_4(&map, 0);

SEE ALSO
     bus_activate_resource(9), bus_alloc_resource(9), bus_space(9), device(9),
     driver(9)

AUTHORS
     This manual page was written by John Baldwin <jhb@FreeBSD.org>.

FreeBSD 13.1-RELEASE-p6        February 5, 2018        FreeBSD 13.1-RELEASE-p6