NAME
bus_activate_resource,
bus_deactivate_resource —
activate or deactivate a
resource
SYNOPSIS
#include
<sys/param.h>
#include <sys/bus.h>
#include <machine/bus.h>
#include <sys/rman.h>
#include
<machine/resource.h>
int
bus_activate_resource(device_t
dev, int type, int rid,
struct resource *r);
int
bus_deactivate_resource(device_t
dev, int type, int rid,
struct resource *r);
DESCRIPTION
These functions activate or deactivate a previously allocated resource. In general, resources must be activated before they can be accessed by the driver. Bus drivers may perform additional actions to ensure that the resource is ready to be accessed. For example, the PCI bus driver enables memory decoding in a PCI device's command register when activating a memory resource.The arguments are as follows:
- dev
- The device that requests ownership of the resource. Before allocation, the resource is owned by the parent bus.
- type
- The type of resource you want to allocate. It is one of:
PCI_RES_BUS- for PCI bus numbers
SYS_RES_IRQ- for IRQs
SYS_RES_DRQ- for ISA DMA lines
SYS_RES_IOPORT- for I/O ports
SYS_RES_MEMORY- for I/O memory
- rid
- A pointer to a bus specific handle that identifies the resource being allocated.
- r
- A pointer to the struct resource returned by bus_alloc_resource(9).
Resource Mapping
Resources which can be mapped for CPU access by a bus_space(9) tag and handle will create a mapping of the entire resource when activated. The tag and handle for this mapping are stored in r and can be retrieved via rman_get_bustag(9) and rman_get_bushandle(9). These can be used with the bus_space(9) API to access device registers or memory described by r. If the mapping is associated with a virtual address, the virtual address can be retrieved via rman_get_virtual(9).
This implicit mapping can be disabled by passing the
RF_UNMAPPED flag to
bus_alloc_resource(9). A driver may use this if it wishes to
allocate its own mappings of a resource using
bus_map_resource(9).
A wrapper API for
bus_space(9) is also provided that accepts the associated
resource as the first argument in place of the
bus_space(9) tag and handle. The functions in this wrapper
API are named similarly to the
bus_space(9) API except that “_space” is
removed from their name. For example,
bus_read_4()
can be used in place of
bus_space_read_4().
The wrapper API is preferred in new drivers.
These two statements both read a 32-bit register at the start of a resource:
bus_space_read_4(rman_get_bustag(res), rman_get_bushandle(res), 0); bus_read_4(res, 0);
RETURN VALUES
Zero is returned on success, otherwise an error is returned.
SEE ALSO
bus_alloc_resource(9), bus_map_resource(9), bus_space(9), device(9), driver(9)
AUTHORS
This manual page was written by Warner Losh <imp@FreeBSD.org>.