DDI_DMA_ADDR_BIND_HANDLE(9F) Kernel Functions for Drivers

NAME

ddi_dma_addr_bind_handle - binds an address to a DMA handle

SYNOPSIS

#include <sys/ddi.h>
#include <sys/sunddi.h>


int ddi_dma_addr_bind_handle(ddi_dma_handle_t handle, struct as *as,
caddr_t addr, size_t len, uint_t flags, int (*callback) (caddr_t) ,
caddr_t arg, ddi_dma_cookie_t *cookiep, uint_t *ccountp);

INTERFACE LEVEL

illumos DDI specific (illumos DDI).

PARAMETERS

handle
The DMA handle previously allocated by a call to
ddi_dma_alloc_handle(9F).


as
A pointer to an address space structure. This parameter
should be set to NULL, which implies kernel address space.


addr
Virtual address of the memory object.


len
Length of the memory object in bytes.


flags
Valid flags include:

DDI_DMA_WRITE
Transfer direction is from memory to
I/O.


DDI_DMA_READ
Transfer direction is from I/O to
memory.


DDI_DMA_RDWR
Both read and write.


DDI_DMA_REDZONE
Establish an MMU redzone at end of
the object.


DDI_DMA_PARTIAL
Partial resource allocation.


DDI_DMA_CONSISTENT
Nonsequential, random, and small
block transfers.


DDI_DMA_STREAMING
Sequential, unidirectional, block-
sized, and block-aligned transfers.


callback
The address of a function to call back later if resources
are not currently available. The following special function
addresses may also be used.

DDI_DMA_SLEEP
Wait until resources are available.


DDI_DMA_DONTWAIT
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 ddi_dma_cookie(9S) structure. This
should be left as NULL in new callers.


ccountp
Upon a successful return, ccountp points to a value
representing the number of cookies for this DMA object.
This can be left as NULL in new callers. The cookie count
can be obtained by calling ddi_dma_ncookies(9F).

DESCRIPTION

ddi_dma_addr_bind_handle() 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
ddi_dma_attr(9S) (see ddi_dma_alloc_handle(9F)).


ddi_dma_addr_bind_handle() allocates and associates a number of DMA
cookies with handle. To get the total number of cookies, callers should
use the ddi_dma_ncookies(9F) function. To get all of the cookies, callers
should use the ddi_dma_cookie_iter(9F) or ddi_dma_cookie_get(9F)
functions. Callers should pass NULL for cookiep and ccountp. These
values are required if using the deprecated ddi_dma_nextcookie(9F)
interface, in which case cookiep is filled in with the first
ddi_dma_cookie(9S) structure.


When a DMA transfer completes, the driver frees up system DMA resources
by calling ddi_dma_unbind_handle(9F).


The flags argument contains information for mapping routines.

DDI_DMA_WRITE, DDI_DMA_READ, DDI_DMA_RDWR

These flags describe the intended direction of the DMA transfer.


DDI_DMA_STREAMING

This flag should be set if the device is doing sequential,
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,
ddi_dma_attr(9S) (see ddi_dma_alloc_handle(9F)) is used to allocate
the most effective hardware support for large transfers.


DDI_DMA_CONSISTENT

This flag should be set if the device accesses memory randomly, or
if synchronization steps using ddi_dma_sync(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
DDI_DMA_CONSISTENT.


DDI_DMA_REDZONE

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.


DDI_DMA_PARTIAL

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 resources for a portion of the object are
allocated. The system indicates this condition by returning status
DDI_DMA_PARTIAL_MAP. At a later point, the caller can use
ddi_dma_getwin(9F) to change the valid portion of the object for
which resources are allocated. If resources were allocated for only
part of the object, ddi_dma_addr_bind_handle() returns resources for
the first DMA window. Even when DDI_DMA_PARTIAL is set, the system
may decide to allocate resources for the entire object (less
overhead) in which case DDI_DMA_MAPPED 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
DDI_DMA_DONTWAIT, the caller does not care if the allocation fails, and
can handle an allocation failure appropriately. If callback is set to
DDI_DMA_SLEEP, 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 DDI_DMA_CALLBACK_RUNOUT
or DDI_DMA_CALLBACK_DONE. DDI_DMA_CALLBACK_RUNOUT 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. DDI_DMA_CALLBACK_DONE 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. Therefore, only
system functions accessible from interrupt context are be available. The
callback function must take whatever steps are necessary to protect its
critical resources, data structures, queues, and so on.

RETURN VALUES

ddi_dma_addr_bind_handle() returns:

DDI_DMA_MAPPED
Successfully allocated resources for the entire
object.


DDI_DMA_PARTIAL_MAP
Successfully allocated resources for a part of
the object. This is acceptable when partial
transfers are permitted by setting the
DDI_DMA_PARTIAL flag in flags.


DDI_DMA_INUSE
Another I/O transaction is using the DMA handle.


DDI_DMA_NORESOURCES
No resources are available at the present time.


DDI_DMA_NOMAPPING
The object cannot be reached by the device
requesting the resources.


DDI_DMA_TOOBIG
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

ddi_dma_addr_bind_handle() can be called from user, kernel, or interrupt
context, except when callback is set to DDI_DMA_SLEEP, in which case it
can only be called from user or kernel context.

SEE ALSO

ddi_dma_alloc_handle(9F), ddi_dma_cookie_get(9F),
ddi_dma_cookie_iter(9F), ddi_dma_free_handle(9F), ddi_dma_getwin(9F),
ddi_dma_mem_alloc(9F), ddi_dma_mem_free(9F), ddi_dma_ncookies(9F),
ddi_dma_sync(9F), ddi_dma_unbind_handle(9F), ddi_umem_iosetup(9F),
ddi_dma_attr(9S), ddi_dma_cookie(9S)


Writing Device Drivers

NOTES

If the driver permits partial mapping with the DDI_DMA_PARTIAL flag, the
number of cookies in each window may exceed the size of the device's
scatter/gather list as specified in the dma_attr_sgllen field in the
ddi_dma_attr(9S) structure. In this case, each set of cookies comprising
a DMA window will satisfy the DMA attributes as described in the
ddi_dma_attr(9S) structure in all aspects. The driver should set up its
DMA engine and perform 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 ddi_dma_getwin(9F).

August 22, 2023 DDI_DMA_ADDR_BIND_HANDLE(9F)