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:

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).