BUS_ACTIVATE_RESOURCE(9)                     FreeBSD Kernel Developer's Manual

NAME
     bus_activate_resource, bus_deactivate_resource - activate or deactivate a
     resource

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

     #include <machine/bus.h>
     #include <sys/rman.h>
     #include <machine/resource.h>

     int
     bus_activate_resource(device_t dev, int type, int rid,
         struct resource *r);

     int
     bus_deactivate_resource(device_t dev, int type, int rid,
         struct resource *r);

DESCRIPTION
     These functions activate or deactivate a previously allocated resource.
     In general, resources must be activated before they can be accessed by
     the driver.  Bus drivers may perform additional actions to ensure that
     the resource is ready to be accessed.  For example, the PCI bus driver
     enables memory decoding in a PCI device's command register when
     activating a memory resource.

     The arguments are as follows:

     dev     The device that requests ownership of the resource.  Before
             allocation, the resource is owned by the parent bus.

     type    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     A pointer to a bus specific handle that identifies the resource
             being allocated.

     r       A pointer to the struct resource returned by
             bus_alloc_resource(9).

   Resource Mapping
     Resources which can be mapped for CPU access by a bus_space(9) tag and
     handle will create a mapping of the entire resource when activated.  The
     tag and handle for this mapping are stored in r and can be retrieved via
     rman_get_bustag(9) and rman_get_bushandle(9).  These can be used with the
     bus_space(9) API to access device registers or memory described by r.  If
     the mapping is associated with a virtual address, the virtual address can
     be retrieved via rman_get_virtual(9).

     This implicit mapping can be disabled by passing the RF_UNMAPPED flag to
     bus_alloc_resource(9).  A driver may use this if it wishes to allocate
     its own mappings of a resource using bus_map_resource(9).

     A wrapper API for bus_space(9) is also provided that accepts the
     associated resource as the first argument in place of the bus_space(9)
     tag and handle.  The functions in this wrapper API are named similarly to
     the bus_space(9) API except that "_space" is removed from their name.
     For example, bus_read_4() can be used in place of bus_space_read_4().
     The wrapper API is preferred in new drivers.

     These two statements both read a 32-bit register at the start of a
     resource:

             bus_space_read_4(rman_get_bustag(res), rman_get_bushandle(res), 0);
             bus_read_4(res, 0);

RETURN VALUES
     Zero is returned on success, otherwise an error is returned.

SEE ALSO
     bus_alloc_resource(9), bus_map_resource(9), bus_space(9), device(9),
     driver(9)

AUTHORS
     This manual page was written by Warner Losh <imp@FreeBSD.org>.

FreeBSD 13.1-RELEASE-p6          May 20, 2016          FreeBSD 13.1-RELEASE-p6