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, struct resource *r, struct resource_map_request *args, struct resource_map *map);
int
bus_unmap_resource(device_t dev, 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.

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>.