Copyright (c) 2016 John H. Baldwin <jhb@FreeBSD.org> All rights reserved. Redistribution and use in source and binary forms, with or without modification, are permitted provided that the following conditions are met: 1. Redistributions of source code must retain the above copyright notice, this list of conditions and the following disclaimer. 2. Redistributions in binary form must reproduce the above copyright notice, this list of conditions and the following disclaimer in the doc...
NAMEbus_map_resource , bus_unmap_resource , resource_init_map_request - map or unmap an active resource
SYNOPSISIn 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
DESCRIPTIONThese 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:
- for I/O ports
- 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 MappingsResource 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 PropertiesThe 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.
- Specifies a memory attribute to use when mapping the resource. By default memory mappings use the VM_MEMATTR_UNCACHEABLE attribute.
EXAMPLESThis 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);