bus_alloc_resource(9)

NAME

bus_alloc_resource, bus_alloc_resource_any - allocate re

sources 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, u_long
start,
        u_long end, u_long count, u_int flags);
struct resource *
bus_alloc_resource_any(device_t dev,  int  type,  int  *rid,
u_int flags);

DESCRIPTION

This is an easy interface to the resource-management func

tions. 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() function is a convenience wrap

per for
bus_alloc_resource(). It sets the values for start, end,

and count to
the default resource (see description of start below).

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:

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 re

source being
allocated. For ISA this is an index into an array of re

sources that have
been setup for this device by either the PnP mechanism, or

via the hints
mechanism. For PCCARD, similar things are used as of writ

ing, but that
may change in the future with newcard. For PCI it just hap

pens to be the
offset into pci config space which has a word that describes

the
resource. The bus methods are free to change the RIDs that

they are
given as a parameter. You must not depend on the value you

gave it earlier.

start and end are the start/end addresses of the resource.

If you specify values of 0ul for start and ~0ul for end and 1 for

count, the 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_SHAREABLE resource permits contemporaneous sharing. It

should always

be set unless you know that the resource can

not 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_TIMESHARE resource permits time-division sharing.

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_release_resource(9), de

vice(9), driver(9)

AUTHORS

This manual page was written by Alexander Langer

<alex@big.endian.de>
with parts by Warner Losh <imp@FreeBSD.org>.

BSD May 18, 2000

BSD