scsi_dmaget, scsi_dmafree - SCSI dma utility routines
#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);
A pointer to a scsi_pkt(9S) structure.
Pointer to an implementation dependent object.
Pointer to a callback function, or NULL_FUNC or SLEEP_FUNC.
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:
Do not wait for resources. Return a NULL pointer.
Wait indefinitely for resources.
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.
The scsi_dmaget() function 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 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.
See attributes(5) for a description of the following attributes:
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 These functions have been replaced by, respectively, scsi_init_pkt(9F) and scsi_destroy_pkt(9F).