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(5) for a description of the following attributes:


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

SEE ALSO


attributes(5), 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)