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NAME

     rman, rman_activate_resource, rman_await_resource, rman_deactivate_resource, rman_fini,
     rman_init, rman_manage_region, rman_release_resource, rman_reserve_resource,
     rman_reserve_resource_bound, rman_make_alignment_flags, rman_get_start, rman_get_end,
     rman_get_device, rman_get_size, rman_get_flags, rman_set_virtual, rman_get_virtual,
     rman_set_bustag, rman_get_bustag, rman_set_bushandle, rman_get_bushandle, rman_set_rid,
     rman_get_rid — resource management functions

SYNOPSIS

     #include <sys/rman.h>

     int
     rman_activate_resource(struct resource *r);

     int
     rman_await_resource(struct resource *r, int pri2, int timo);

     int
     rman_deactivate_resource(struct resource *r);

     int
     rman_fini(struct rman *rm);

     int
     rman_init(struct rman *rm);

     int
     rman_manage_region(struct rman *rm, u_long start, u_long end);

     int
     rman_release_resource(struct resource *r);

     struct resource *
     rman_reserve_resource(struct rman *rm, u_long start, u_long end, u_long count, u_int flags,
         struct device *dev);

     struct resource *
     rman_reserve_resource_bound(struct rman *rm, u_long start, u_long end, u_long count,
         u_long bound, u_int flags, struct device *dev);

     uint32_t
     rman_make_alignment_flags(uint32_t size);

     u_long
     rman_get_start(struct resource *r);

     u_long
     rman_get_end(struct resource *r);

     struct device *
     rman_get_device(struct resource *r);

     u_long
     rman_get_size(struct resource *r);

     u_int
     rman_get_flags(struct resource *r);

     void
     rman_set_virtual(struct resource *r, void *v);

     void *
     rman_get_virtual(struct resource *r);

     void
     rman_set_bustag(struct resource *r, bus_space_tag_t t);

     bus_space_tag_t
     rman_get_bustag(struct resource *r);

     void
     rman_set_bushandle(struct resource *r, bus_space_handle_t h);

     bus_space_handle_t
     rman_get_bushandle(struct resource *r);

     void
     rman_set_rid(struct resource *r, int rid);

     int
     rman_get_rid(struct resource *r);

DESCRIPTION

     The rman set of functions provides a flexible resource management abstraction.  It is used
     extensively by the bus management code.  It implements the abstractions of region and
     resource.  A region descriptor is used to manage a region; this could be memory or some
     other form of bus space.

     Each region has a set of bounds.  Within these bounds, allocated segments may reside.  Each
     segment, termed a resource, has several properties which are represented by a 16-bit flag
     register, as follows.

     #define RF_ALLOCATED    0x0001 /* resource has been reserved */
     #define RF_ACTIVE       0x0002 /* resource allocation has been activated */
     #define RF_SHAREABLE    0x0004 /* resource permits contemporaneous sharing */
     #define RF_TIMESHARE    0x0008 /* resource permits time-division sharing */
     #define RF_WANTED       0x0010 /* somebody is waiting for this resource */
     #define RF_FIRSTSHARE   0x0020 /* first in sharing list */
     #define RF_PREFETCHABLE 0x0040 /* resource is prefetchable */

     The remainder of the flag bits are used to represent the desired alignment of the resource
     within the region.

     The rman_init() function initializes the region descriptor, pointed to by the rm argument,
     for use with the resource management functions.  It is required that the fields rm_type and
     rm_descr of struct rman be set before calling rman_init().  The field rm_type shall be set
     to RMAN_ARRAY.  The field rm_descr shall be set to a string that describes the resource to
     be managed.  It also initializes any mutexes associated with the structure.  If rman_init()
     fails to initalize the mutex, it will return ENOMEM; otherwise it will return 0 and rm will
     be initalized.

     The rman_fini() function frees any structures associated with the structure pointed to by
     the rm argument.  If any of the resources within the managed region have the RF_ALLOCATED
     flag set, it will return EBUSY; otherwise, any mutexes associated with the structure will be
     released and destroyed, and the function will return 0.

     The rman_manage_region() function establishes the concept of a region which is under rman
     control.  The rman argument points to the region descriptor.  The start and end arguments
     specify the bounds of the region.  If successful, rman_manage_region() will return 0.  If
     the region overlaps with an existing region, it will return EBUSY.  ENOMEM will be return
     when rman_manage_region() failed to allocate memory for the region.

     The rman_reserve_resource_bound() function is where the bulk of the rman logic is located.
     It attempts to reserve a contiguous range in the specified region rm for the use of the
     device dev.  The caller can specify the start and end of an acceptable range, as well as
     alignment, and the code will attempt to find a free segment which fits.  The start argument
     is the lowest acceptable starting value of the resource.  The end argument is the highest
     acceptable ending value of the resource.  Therefore, start + count - 1 must be ≤ end for any
     allocation to happen.  The default behavior is to allocate an exclusive segment, unless the
     RF_SHAREABLE or RF_TIMESHARE flags are set, in which case a shared segment will be
     allocated.  If this shared segment already exists, the caller has its device added to the
     list of consumers.

     The rman_reserve_resource() function is used to reserve resources within a previously
     established region.  It is a simplified interface to rman_reserve_resource_bound() which
     passes 0 for the flags argument.

     The rman_make_alignment_flags() function returns the flag mask corresponding to the desired
     alignment size.  This should be used when calling rman_reserve_resource_bound().

     The rman_release_resource() function releases the reserved resource r.  It may attempt to
     merge adjacent free resources.

     The rman_activate_resource() function marks a resource as active, by setting the RF_ACTIVE
     flag.  If this is a time shared resource, and the caller has not yet acquired the resource,
     the function returns EBUSY.

     The rman_deactivate_resource() function marks a resource r as inactive, by clearing the
     RF_ACTIVE flag.  If other consumers are waiting for this range, it will wakeup their
     threads.

     The rman_await_resource() function performs an asynchronous wait for a resource r to become
     inactive, that is, for the RF_ACTIVE flag to be cleared.  It is used to enable cooperative
     sharing of a resource which can only be safely used by one thread at a time.  The arguments
     pri and timo are passed to the rman_await_resource() function.

     The rman_get_start(), rman_get_end(), rman_get_size(), and rman_get_flags() functions return
     the bounds, size and flags of the previously reserved resource r.

     The rman_set_bustag() function associates a bus_space_tag_t t with the resource r.  The
     rman_get_bustag() function is used to retrieve this tag once set.

     The rman_set_bushandle() function associates a bus_space_handle_t h with the resource r.
     The rman_get_bushandle() function is used to retrieve this handle once set.

     The rman_set_virtual() function is used to associate a kernel virtual address with a
     resource r.  The rman_get_virtual() function can be used to retrieve the KVA once set.

     The rman_set_rid() function associates a resource identifier with a resource r.  The
     rman_get_rid() function retrieves this RID.

     The rman_get_device() function returns a pointer to the device which reserved the resource
     r.

SEE ALSO

     bus_activate_resource(9), bus_alloc_resource(9), bus_release_resource(9),
     bus_set_resource(9), mutex(9)

AUTHORS

     This manual page was written by Bruce M Simpson <bms@spc.org>.