Solaris DDI specific (Solaris DDI).

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.

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

dmatoken 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.

callback 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 resouces 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.

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

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

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

scsi_dmafree() can be called from user or interrupt context.

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

Writing Device Drivers