NAME¶
bus_alloc_resource
,
bus_alloc_resource_any
—
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,
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 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
() function is a
convenience wrapper 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 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 described by the PC Card's CIS entry. For PCI, the
offset into pci config space which has the BAR to use to access 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 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_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_adjust_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⟩.