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.\" $FreeBSD: src/share/man/man9/bus_alloc_resource.9,v 1.2.2.10 2004/03/17 17:54:24 njl Exp $
.\"
.Dd May 18, 2000
.Dt BUS_ALLOC_RESOURCE 9
.Os
.Sh NAME
.Nm bus_alloc_resource ,
.Nm bus_alloc_resource_any
.Nd alloc resources on a bus
.Sh SYNOPSIS
.In sys/param.h
.In sys/bus.h
.Pp
.In sys/rman.h
.In sys/resource.h
.Ft struct resource *
.Fn bus_alloc_resource "device_t dev" "int type" "int *rid" "u_long start" "u_long end" "u_long count" "u_int flags"
.Ft struct resource *
.Fn bus_alloc_resource_any "device_t dev" "int type" "int *rid" "u_int flags"
.Sh 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
race cases) never earlier.
.Pp
The
.Fn bus_alloc_resource_any
function is a convenience wrapper for
.Fn bus_alloc_resource .
It sets the values for
.Fa start ,
.Fa end ,
and
.Fa count
to the default resource (see description of
.Fa start
below).
.Pp
The arguments are as follows:
.Bl -item
.It
.Fa dev
is the device that requests ownership of the resource.
Before allocation, the resource is owned by the parent bus.
.It
.Fa type
is the type of resource you want to allocate.
It is one of:
.Bl -tag -width ".Dv SYS_RES_MEMORY"
.It Dv SYS_RES_IRQ
for IRQs
.It Dv SYS_RES_DRQ
for ISA DMA lines
.It Dv SYS_RES_IOPORT
for I/O ports
.It Dv SYS_RES_MEMORY
for I/O memory
.El
.It
.Fa 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, similar things are used as of writing,
but that may change in the future with newcard.
For PCI it just happens 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.
.It
.Fa start
and
.Fa end
are the start/end addresses of the resource.
If you specify values of
.Dv 0
for start and
.Dv ~0
for end, the default values for the bus are calculated.
.It
.Fa count
is the size of the resource, e.g. the size of an I/O port (often
.Dv 1
on PCI and device-dependent on ISA and PCCARD).
If you specified the default values for
.Fa start
and
.Fa end ,
then the default value of the bus is used if
.Fa count
is smaller than the default value and
.Fa count
is used, if it is bigger than the default value.
.It
.Fa flags
sets the flags for the resource.
You can set one or more of these flags:
.Bl -tag -width ".Dv RF_SHAREABLE"
.It Dv RF_ALLOCATED
resource has been reserved.
The resource still needs to be activated with
.Xr rman_activate_resource 9 .
.It Dv RF_ACTIVE
activate resource atomically.
.It Dv RF_SHAREABLE
resource permits contemporaneous sharing.
Should always be set unless you know, that the resource cannot be shared.
It is the bus-code's task to filter out the flag if the bus doesn't
support sharing, which is, for example, the case for pccard/cardbus,
which can or cannot share devices, depending on the bus.
.It Dv RF_TIMESHARE
resource permits time-division sharing.
.El
.El
.Sh RETURN VALUES
A pointer to
.Va struct res
is returned on success, a null pointer otherwise.
.Sh EXAMPLES
This is some example code.
The values of
.Va portid
and
.Va irqid
should be saved in the softc of the device after these calls.
.Bd -literal
	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);
.Ed
.Sh SEE ALSO
.Xr bus_release_resource 9 ,
.Xr device 9 ,
.Xr driver 9
.Sh AUTHORS
.An -nosplit
This man page was written by
.An Alexander Langer Aq Mt alex@big.endian.de
with parts by
.An Warner Losh Aq Mt imp@FreeBSD.org .