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BUS_ALLOC_RESOURCE(9) 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() func- tions are convenience wrappers for bus_alloc_resource(). bus_alloc_resource_any() sets start, end, and count to the default re- source (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 al- location, 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 is a bus specific handle that identifies the resource being allo- cated. 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 re- sources 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. 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 speci- fied 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 zero or more of these flags: 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. 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. struct resource *portres, *irqres; portres = bus_alloc_resource(dev, SYS_RES_IOPORT, 0, 0ul, ~0ul, 32, RF_ACTIVE); irqres = bus_alloc_resource_any(dev, SYS_RES_IRQ, 0, 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 ports 15.1 March 6, 2026 BUS_ALLOC_RESOURCE(9)
NAME | SYNOPSIS | DESCRIPTION | RETURN VALUES | EXAMPLES | SEE ALSO | AUTHORS
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