Kernel Functions for Drivers ddidmaaddrbindhandle(9F)
NAME
ddidmaaddrbindhandle - binds an address to a DMA handle
SYNOPSIS
#include
#include
int ddidmaaddrbindhandle(ddidmahandlet handle, struct as *as,
caddrt addr, sizet len, uintt flags, int (*callback) (caddrt) ,
caddrt arg, ddidmacookiet *cookiep, uintt *ccountp);
INTERFACE LEVEL
Solaris DI specific (Solaris DI).
PARAMETERS
handle The DMA handle previously allocated by a call
to ddidmaallochandle(9F).
as A pointer to an address space structure. This
parameter should be set to NUL, which implies
kernel address space.
addr Virtual address of the memory object.
len Length of the memory object in bytes.
flags Valid flags include:
DIDMAWRITE Transfer direction is
from memory to I/O.
DIDMAREAD Transfer direction is
from I/O to memory.
DIDMARDWR Both read and write.
DIDMAREDZONE Establish an MU redzone
at end of the object.
DIDMAPARTIAL Partial resource alloca-
tion.
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Kernel Functions for Drivers ddidmaaddrbindhandle(9F)
DIDMACONSISTENT Nonsequential, random,
and small block
transfers.
DIDMASTREAMING Sequential, unidirec-
tional, block-sized, and
block-aligned transfers.
callback The address of a function to call back later if
resources are not currently available. The fol-
lowing special function addresses may also be
used.
DIDMASLEP Wait until resources are
available.
DIDMADONTWAIT Do not wait until
resources are available
and do not schedule a
callback.
arg Argument to be passed to the callback function,
callback, if such a function is specified.
cookiep A pointer to the first ddidmacookie(9S)
structure.
ccountp Upon a successful return, ccountp points to a
value representing the number of cookies for
this DMA object.
DESCRIPTION
ddidmaaddrbindhandle() allocates DMA resources for a
memory object such that a device can perform DMA to or from
the object. DMA resources are allocated considering the
device's DMA attributes as expressed by ddidmaattr(9S)
(see ddidmaallochandle(9F)).
ddidmaaddrbindhandle() fills in the first DMA cookie
pointed to by cookiep with the appropriate address, length,
and bus type. *ccountp is set to the number of DMA cookies
representing this DMA object. Subsequent DMA cookies must be
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Kernel Functions for Drivers ddidmaaddrbindhandle(9F)
retrieved by calling ddidmanextcookie(9F) the number of
times specified by *countp-1.
When a DMA transfer completes, the driver frees up system
DMA resources by calling ddidmaunbindhandle(9F).
The flags argument contains information for mapping rou-
tines.
DIDMAWRITE, DIDMAREAD, DIDMARDWR
These flags describe the intended direction of the DMA
transfer.
DIDMASTREAMING
This flag should be set if the device is doing sequen-
tial, unidirectional, block-sized, and block-aligned
transfers to or from memory. The alignment and padding
constraints specified by the minxfer and burstsizes
fields in the DMA attribute structure, ddidmaattr(9S)
(see ddidmaallochandle(9F)) is used to allocate the
most effective hardware support for large transfers.
DIDMACONSISTENT
This flag should be set if the device accesses memory
randomly, or if synchronization steps using
ddidmasync(9F) need to be as efficient as possible.
I/O parameter blocks used for communication between a
device and a driver should be allocated using
DIDMACONSISTENT.
DIDMAREDZONE
If this flag is set, the system attempts to establish a
protected red zone after the object. The DMA resource
allocation functions do not guarantee the success of
this request as some implementations may not have the
hardware ability to support a red zone.
DIDMAPARTIAL
Setting this flag indicates the caller can accept
resources for part of the object. That is, if the size
of the object exceeds the resources available, only
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Kernel Functions for Drivers ddidmaaddrbindhandle(9F)
resources for a portion of the object are allocated. The
system indicates this condition by returning status
DIDMAPARTIALMAP. At a later point, the caller can
use ddidmagetwin(9F) to change the valid portion of
the object for which resources are allocated. If
resources were allocated for only part of the object,
ddidmaaddrbindhandle() returns resources for the
first DMAwindow. Even when DIDMAPARTIAL is set, the
system may decide to allocate resources for the entire
object (less overhead) in which case DIDMAMAPED is
returned.
The callback function callback indicates how a caller wants
to handle the possibility of resources not being available.
If callback is set to DIDMADONTWAIT, the caller does not
care if the allocation fails, and can handle an allocation
failure appropriately. If callback is set to DIDMASLEP,
the caller wishes to have the allocation routines wait for
resources to become available. If any other value is set and
a DMA resource allocation fails, this value is assumed to be
the address of a function to be called when resources
become available. When the specified function is called,
arg is passed to it as an argument. The specified callback
function must return either DIDMACALBACKRUNOUT or
DIDMACALBACKDONE. DIDMACALBACKRUNOUT indicates
that the callback function attempted to allocate DMA
resources but failed. In this case, the callback function
is put back on a list to be called again later.
DIDMACALBACKDONE indicates that either the allocation
of DMA resources was successful or the driver no longer
wishes to retry.
The callback function is called in interrupt context. There-
fore, only system functions accessible from interrupt con-
text are be available. The callback function must take what-
ever steps are necessary to protect its critical resources,
data structures, queues, and so on.
RETURN VALUES
ddidmaaddrbindhandle() returns:
DIDMAMAPED Successfully allocated resources for
the entire object.
DIDMAPARTIALMAP Successfully allocated resources for
a part of the object. This is
acceptable when partial transfers
are permitted by setting the
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Kernel Functions for Drivers ddidmaaddrbindhandle(9F)
DIDMAPARTIAL flag in flags.
DIDMAINUSE Another I/O transaction is using the
DMA handle.
DIDMANORESOURCES No resources are available at the
present time.
DIDMANOMAPING The object cannot be reached by the
device requesting the resources.
DIDMATOBIG The object is too big. A request of
this size can never be satisfied on
this particular system. The maximum
size varies depending on machine and
configuration.
CONTEXT
ddidmaaddrbindhandle() can be called from user, kernel,
or interrupt context, except when callback is set to
DIDMASLEP, in which case it can only be called from user
or kernel context.
SEE ALSO
ddidmaallochandle(9F), ddidmafreehandle(9F),
ddidmagetwin(9F), ddidmamemalloc(9F),
ddidmamemfree(9F), ddidmanextcookie(9F),
ddidmasync(9F), ddidmaunbindhandle(9F),
ddiumemiosetup(9F), ddidmaattr(9S), ddidmacookie(9S)
Writing Device Drivers
NOTES
If the driver permits partial mapping with the
DIDMAPARTIAL flag, the number of cookies in each window
may exceed the size of the device's scatter/gather list as
specified in the dmaattrsgllen field in the
ddidmaattr(9S) structure. In this case, each set of cook-
ies comprising a DMA window will satisfy the DMA attributes
as described in the ddidmaattr(9S) structure in all
aspects. The driver should set up its DMA engine and per-
form one transfer for each set of cookies sufficient for its
scatter/gather list, up to the number of cookies for this
window, before advancing to the next window using
ddidmagetwin(9F).
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