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BUS_ALLOC_RESOURCE(9) DragonFly Kernel Developer's ManualBUS_ALLOC_RESOURCE(9)


NAME

     bus_alloc_resource, bus_alloc_resource_any -- alloc resources on a bus


SYNOPSIS

     #include <sys/param.h>
     #include <sys/bus.h>

     #include <sys/rman.h>
     #include <sys/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 gener-
     ally should be called in attach, but (except in some race 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 allo-
     cation, 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, 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 ear-
     lier.

     start and end are the start/end addresses of the resource.  If you spec-
     ify values of 0 for start and ~0 for end, the default values for the bus
     are calculated.

     count is the size of the resource, e.g. the size of an I/O port (often 1
     on PCI and device-dependent on ISA and PCCARD).  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 rman_activate_resource(9).

     RF_ACTIVE     activate resource atomically.

     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.

     RF_TIMESHARE  resource permits time-division sharing.


RETURN VALUES

     A pointer to struct res is returned on success, a null pointer otherwise.


EXAMPLES

     This is some example code.  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_release_resource(9), device(9), driver(9)


AUTHORS

     This man page was written by Alexander Langer <alex@big.endian.de> with
     parts by Warner Losh <imp@FreeBSD.org>.

DragonFly 3.5                    May 18, 2000                    DragonFly 3.5

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