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BUS_ALLOC_RESOURCE(9) FreeBSD Kernel Developer's Manual BUS_ALLOC_RESOURCE(9)
NAME
bus_alloc_resource, bus_alloc_resource_any, bus_alloc_resource_anywhere -
allocate resources from a parent bus
SYNOPSIS
#include <sys/param.h>
#include <sys/bus.h>
#include <machine/bus.h>
#include <sys/rman.h>
#include <machine/resource.h>
struct resource *
bus_alloc_resource(device_t dev, int type, int *rid, rman_res_t start,
rman_res_t end, rman_res_t count, u_int flags);
struct resource *
bus_alloc_resource_any(device_t dev, int type, int *rid, u_int flags);
struct resource *
bus_alloc_resource_anywhere(device_t dev, int type, int *rid,
rman_res_t count, u_int flags);
DESCRIPTION
This is an easy interface to the resource-management functions. It hides
the indirection through the parent's method table. This function
generally should be called in attach, but (except in some rare cases)
never earlier.
The bus_alloc_resource_any() and bus_alloc_resource_anywhere() functions
are convenience wrappers for bus_alloc_resource().
bus_alloc_resource_any() sets start, end, and count to the default
resource (see description of start below). bus_alloc_resource_anywhere()
sets start and end to the default resource and uses the provided count
argument.
The arguments are as follows:
dev is the device that requests ownership of the resource. Before
allocation, the resource is owned by the parent bus.
type is 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 points to a bus specific handle that identifies the resource being
allocated. For ISA this is an index into an array of resources that have
been setup for this device by either the PnP mechanism, or via the hints
mechanism. For PCCARD, this is an index into the array of resources
default values for the bus are calculated.
count is the size of the resource. For example, the size of an I/O port
is usually 1 byte (but some devices override this). If you specified the
default values for start and end, then the default value of the bus is
used if count is smaller than the default value and count is used, if it
is bigger than the default value.
flags sets the flags for the resource. You can set one or more of these
flags:
RF_ALLOCATED resource has been reserved. The resource still needs to be
activated with bus_activate_resource(9).
RF_ACTIVE activate resource atomically.
RF_PREFETCHABLE
resource is prefetchable.
RF_SHAREABLE resource permits contemporaneous sharing. It should always
be set unless you know that the resource cannot be shared.
It is the bus driver's task to filter out the flag if the
bus does not support sharing. For example, pccard(4)
cannot share IRQs while cardbus(4) can.
RF_UNMAPPED do not establish implicit mapping when activated via
bus_activate_resource(9).
RETURN VALUES
A pointer to struct resource is returned on success, a null pointer
otherwise.
EXAMPLES
This is some example code that allocates a 32 byte I/O port range and an
IRQ. The values of portid and irqid should be saved in the softc of the
device after these calls.
struct resource *portres, *irqres;
int portid, irqid;
portid = 0;
irqid = 0;
portres = bus_alloc_resource(dev, SYS_RES_IOPORT, &portid,
0ul, ~0ul, 32, RF_ACTIVE);
irqres = bus_alloc_resource_any(dev, SYS_RES_IRQ, &irqid,
RF_ACTIVE | RF_SHAREABLE);
SEE ALSO
bus_activate_resource(9), bus_adjust_resource(9), bus_map_resource(9),
bus_release_resource(9), device(9), driver(9)
AUTHORS
This manual page was written by Alexander Langer <alex@big.endian.de>
with parts by Warner Losh <imp@FreeBSD.org>.
FreeBSD 14.0-RELEASE-p6 May 20, 2016 FreeBSD 14.0-RELEASE-p6