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; |
||
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struct resource_map_request req; |
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uint32_t val; |
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int rid; |
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rid = PCIR_BAR(0); |
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r = bus_alloc_resource_any(dev, SYS_RES_MEMORY, &rid, RF_ACTIVE | |
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RF_UNMAPPED); |
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resource_init_map_request(&req); |
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req.memattr = VM_MEMATTR_WRITE_COMBINING; |
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bus_map_resource(dev, SYS_RES_MEMORY, r, &req, &map); |
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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 [AT] FreeBSD.org>.
BSD February 5, 2018 BSD