bus_map_resource (9)

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Copyright (c) 2016 John H. Baldwin <jhb@FreeBSD.org>
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(The comments found at the beginning of the groff file "man9/bus_map_resource.9freebsd".)

NAME

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

SYNOPSIS

In sys/param.h In sys/bus.h

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

DESCRIPTION

These functions create or destroy a mapping of a previously activated resource. Mappings permit CPU access to the resource via the bus_space9 API.

The arguments are as follows:

Fa dev

The device that owns the resource.

Fa 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

Fa r

A pointer to the Vt struct resource returned by bus_alloc_resource9.

Fa 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.

Fa map

The resource mapping to create or destroy.

Resource Mappings

Resource mappings are described by a Vt struct resource_map object. This structure contains a bus_space9 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 Vt struct resource objects described in bus_activate_resource9 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 r_bustag and r_bushandle members directly.

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:

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.

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_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);

RETURN VALUES

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

SEE ALSO

bus_activate_resource9, bus_alloc_resource9, bus_space9, device(9), driver(9)

AUTHORS

This manual page was written by An John Baldwin Aq Mt jhb@FreeBSD.org .