BUS_UNMAP_RESOURCE(9FREEBSD) - Linux man page online | System kernel interfaces

Map or unmap an active resource.

May 20, 2016
BUS_MAP_RESOURCE(9) BSD Kernel Developer's Manual BUS_MAP_RESOURCE(9)


bus_map_resource, bus_unmap_resource, resource_init_map_request — map or unmap an active resource


#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);


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 vir‐ tual 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 prop‐ erties 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.


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_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);


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


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


This manual page was written by John Baldwin <>.
BSD May 20, 2016 BSD
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bus_unmap_resource(9freebsd) referred by
refer to bus_activate_resource(9freebsd) | bus_alloc_resource(9freebsd) | bus_map_resource(9freebsd) | bus_space(9freebsd) | device(9freebsd) | driver(9freebsd)
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