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>.

Debian                                            May 20, 2016                          BUS_ACTIVATE_RESOURCE(9)