SCSI_DMAGET(9F) Kernel Functions for Drivers SCSI_DMAGET(9F)

NAME

scsi_dmaget, scsi_dmafree - SCSI dma utility routines

SYNOPSIS

#include <sys/scsi/scsi.h>


struct scsi_pkt *scsi_dmaget(struct scsi_pkt *pkt,
opaque_t dmatoken, int(*callback)(void));


void scsi_dmafree(struct scsi_pkt *pkt);

INTERFACE LEVEL

These interfaces are obsolete. Use scsi_init_pkt(9F) instead of
scsi_dmaget(). Use scsi_destroy_pkt(9F) instead of scsi_dmafree().

PARAMETERS

pkt
A pointer to a scsi_pkt(9S) structure.


dmatoken
Pointer to an implementation dependent object.


callback
Pointer to a callback function, or NULL_FUNC or
SLEEP_FUNC.

DESCRIPTION

The scsi_dmaget() function allocates DMA resources for an already
allocated SCSI packet. pkt is a pointer to the previously allocated
SCSI packet (see scsi_pktalloc(9F)).


The dmatoken parameter is a pointer to an implementation dependent
object which defines the length, direction, and address of the data
transfer associated with this SCSI packet (command). The dmatoken
must be a pointer to a buf(9S) structure. If dmatoken is NULL, no
resources are allocated.


The callback parameter indicates what scsi_dmaget() should do when
resources are not available:

NULL_FUNC
Do not wait for resources. Return a NULL pointer.


SLEEP_FUNC
Wait indefinitely for resources.


Other Values
callback points to a function which is called when
resources may have become available. callback must
return either 0 (indicating that it attempted to
allocate resources but failed to do so again), in
which case it is put back on a list to be called
again later, or 1 indicating either success in
allocating resources or indicating that it no longer
cares for a retry.


The scsi_dmafree() function frees the DMA resources associated with
the SCSI packet. The packet itself remains allocated.

RETURN VALUES

The scsi_dmaget() function returns a pointer to a scsi_pkt on
success. It returns NULL if resources are not available.

CONTEXT

If callback is SLEEP_FUNC, then this routine may only be called from
user or kernel context. Otherwise, it may be called from user,
kernel, or interrupt context. The callback function may not block or
call routines that block.


The scsi_dmafree() function can be called from user, interrupt, or
kernel context.

ATTRIBUTES

See attributes(7) for a description of the following attributes:


+----------------+-----------------+
|ATTRIBUTE TYPE | ATTRIBUTE VALUE |
+----------------+-----------------+
|Stability Level | Obsolete |
+----------------+-----------------+

SEE ALSO

attributes(7), scsi_pktalloc(9F), scsi_pktfree(9F),
scsi_resalloc(9F), scsi_resfree(9F), buf(9S), scsi_pkt(9S)


Writing Device Drivers

NOTES

The scsi_dmaget() and scsi_dmafree() functions are obsolete and will
be discontinued in a future release. These functions have been
replaced by, respectively, scsi_init_pkt(9F) and
scsi_destroy_pkt(9F).

January 16, 2006 SCSI_DMAGET(9F)