freebsd/share/man/man9/rman.9

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.Dd April 29, 2007
.Dt RMAN 9
.Os
.Sh NAME
.Nm rman ,
.Nm rman_activate_resource ,
.Nm rman_await_resource ,
.Nm rman_deactivate_resource ,
.Nm rman_fini ,
.Nm rman_init ,
.Nm rman_manage_region ,
.Nm rman_release_resource ,
.Nm rman_reserve_resource ,
.Nm rman_reserve_resource_bound ,
.Nm rman_make_alignment_flags ,
.Nm rman_get_start ,
.Nm rman_get_end ,
.Nm rman_get_device ,
.Nm rman_get_size ,
.Nm rman_get_flags ,
.Nm rman_set_virtual ,
.Nm rman_get_virtual ,
.Nm rman_set_bustag ,
.Nm rman_get_bustag ,
.Nm rman_set_bushandle ,
.Nm rman_get_bushandle ,
.Nm rman_set_rid ,
.Nm rman_get_rid
.Nd resource management functions
.Sh SYNOPSIS
.In sys/rman.h
.Ft int
.Fn rman_activate_resource "struct resource *r"
.Ft int
.Fn rman_await_resource "struct resource *r" "int pri2" "int timo"
.Ft int
.Fn rman_deactivate_resource "struct resource *r"
.Ft int
.Fn rman_fini "struct rman *rm"
.Ft int
.Fn rman_init "struct rman *rm"
.Ft int
.Fn rman_manage_region "struct rman *rm" "u_long start" "u_long end"
.Ft int
.Fn rman_release_resource "struct resource *r"
.Ft "struct resource *"
.Fo rman_reserve_resource
.Fa "struct rman *rm" "u_long start" "u_long end" "u_long count"
.Fa "u_int flags" "struct device *dev"
.Fc
.Ft "struct resource *"
.Fo rman_reserve_resource_bound
.Fa "struct rman *rm" "u_long start" "u_long end" "u_long count"
.Fa "u_long bound" "u_int flags" "struct device *dev"
.Fc
.Ft uint32_t
.Fn rman_make_alignment_flags "uint32_t size"
.Ft u_long
.Fn rman_get_start "struct resource *r"
.Ft u_long
.Fn rman_get_end "struct resource *r"
.Ft "struct device *"
.Fn rman_get_device "struct resource *r"
.Ft u_long
.Fn rman_get_size "struct resource *r"
.Ft u_int
.Fn rman_get_flags "struct resource *r"
.Ft void
.Fn rman_set_virtual "struct resource *r" "void *v"
.Ft "void *"
.Fn rman_get_virtual "struct resource *r"
.Ft void
.Fn rman_set_bustag "struct resource *r" "bus_space_tag_t t"
.Ft bus_space_tag_t
.Fn rman_get_bustag "struct resource *r"
.Ft void
.Fn rman_set_bushandle "struct resource *r" "bus_space_handle_t h"
.Ft bus_space_handle_t
.Fn rman_get_bushandle "struct resource *r"
.Ft void
.Fn rman_set_rid "struct resource *r" "int rid"
.Ft int
.Fn rman_get_rid "struct resource *r"
.Sh DESCRIPTION
The
.Nm
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.
.Pp
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.
.Bd -literal
#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 */
.Ed
.Pp
The remainder of the flag bits are used to represent the desired alignment
of the resource within the region.
.Pp
The
.Fn rman_init
function initializes the region descriptor, pointed to by the
.Fa rm
argument, for use with the resource management functions.
It is required that the fields
.Va rm_type
and
.Va rm_descr
of
.Vt "struct rman"
be set before calling
.Fn rman_init .
The field
.Va rm_type
shall be set to
.Dv RMAN_ARRAY .
The field
.Va 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
.Fn rman_init
fails to initalize the mutex, it will return
.Er ENOMEM ; otherwise it will return 0 and
.Fa rm
will be initalized.
.Pp
The
.Fn rman_fini
function frees any structures associated with the structure
pointed to by the
.Fa rm
argument.
If any of the resources within the managed region have the
.Dv RF_ALLOCATED
flag set, it will return
.Er EBUSY ;
otherwise, any mutexes associated with the structure will be released
and destroyed, and the function will return 0.
.Pp
The
.Fn rman_manage_region
function establishes the concept of a region which is under
.Nm
control.
The
.Fa rman
argument points to the region descriptor.
The
.Fa start
and
.Fa end
arguments specify the bounds of the region.
If successful,
.Fn rman_manage_region
will return 0.
If the region overlaps with an existing region, it will return
.Er EBUSY .
.Er ENOMEM
will be return when
.Fn rman_manage_region
failed to allocate memory for the region.
.Pp
The
.Fn rman_reserve_resource_bound
function is where the bulk of the
.Nm
logic is located.
It attempts to reserve a contiguous range in the specified region
.Fa rm
for the use of the device
.Fa dev .
The caller can specify the
.Fa start
and
.Fa end
of an acceptable range, as well as
alignment, and the code will attempt to find a free segment which fits.
The
.Fa start
argument is the lowest acceptable starting value of the resource.
The
.Fa end
argument is the highest acceptable ending value of the resource.
Therefore,
.Fa start No + Fa count No \- 1
must be \[<=]
.Fa end
for any allocation to happen.
The default behavior is to allocate an exclusive segment, unless the
.Dv RF_SHAREABLE
or
.Dv 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.
.Pp
The
.Fn rman_reserve_resource
function is used to reserve resources within a previously established region.
It is a simplified interface to
.Fn rman_reserve_resource_bound
which passes 0 for the
.Fa flags
argument.
.Pp
The
.Fn rman_make_alignment_flags
function returns the flag mask corresponding to the desired alignment
.Fa size .
This should be used when calling
.Fn rman_reserve_resource_bound .
.Pp
The
.Fn rman_release_resource
function releases the reserved resource
.Fa r .
It may attempt to merge adjacent free resources.
.Pp
The
.Fn rman_activate_resource
function marks a resource as active, by setting the
.Dv RF_ACTIVE
flag.
If this is a time shared resource, and the caller has not yet acquired
the resource, the function returns
.Er EBUSY .
.Pp
The
.Fn rman_deactivate_resource
function marks a resource
.Fa r
as inactive, by clearing the
.Dv RF_ACTIVE
flag.
If other consumers are waiting for this range, it will wakeup their threads.
.Pp
The
.Fn rman_await_resource
function performs an asynchronous wait for a resource
.Fa r
to become inactive, that is, for the
.Dv 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
.Fa pri
and
.Fa timo
are passed to the
.Fn rman_await_resource
function.
.Pp
The
.Fn rman_get_start ,
.Fn rman_get_end ,
.Fn rman_get_size ,
and
.Fn rman_get_flags
functions return the bounds, size and flags of the previously reserved
resource
.Fa r .
.Pp
The
.Fn rman_set_bustag
function associates a
.Vt bus_space_tag_t
.Fa t
with the resource
.Fa r .
The
.Fn rman_get_bustag
function is used to retrieve this tag once set.
.Pp
The
.Fn rman_set_bushandle
function associates a
.Vt bus_space_handle_t
.Fa h
with the resource
.Fa r .
The
.Fn rman_get_bushandle
function is used to retrieve this handle once set.
.Pp
The
.Fn rman_set_virtual
function is used to associate a kernel virtual address with a resource
.Fa r .
The
.Fn rman_get_virtual
function can be used to retrieve the KVA once set.
.Pp
The
.Fn rman_set_rid
function associates a resource identifier with a resource
.Fa r .
The
.Fn rman_get_rid
function retrieves this RID.
.Pp
The
.Fn rman_get_device
function returns a pointer to the device which reserved the resource
.Fa r .
.Sh SEE ALSO
.Xr bus_activate_resource 9 ,
.Xr bus_alloc_resource 9 ,
.Xr bus_release_resource 9 ,
.Xr bus_set_resource 9 ,
.Xr mutex 9
.Sh AUTHORS
This manual page was written by
.An Bruce M Simpson Aq bms@spc.org .