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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 also
     initializes any mutexes associated with the structure.

     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.

     NOTE: This interface is not robust against programming errors which add
     multiple copies of the same 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〉.