NAME

ddi_dma_setup - setup DMA resources

SYNOPSIS

#include <sys/ddi.h>

#include <sys/sunddi.h>

int ddi_dma_setup(dev_info_t * dip, ddi_dma_req_t * dmareqp,

ddi_dma_handle_t * handlep);

ARGUMENTS

dip

A pointer to the device's dev_info structure.

dmareqp

A pointer to a DMA request structure (see ddi_dma_req(9S)).

handlep

A pointer to a DMA handle to be filled in. See below for a discussion of a handle. If handlep is NULL, the call to ddi_dma_setup( ) is considered an advisory call, in which case no resources are allocated, but a value indicating the legality and the feasibility of the request is returned.

INTERFACE LEVEL

Solaris DDI specific (Solaris DDI).

DESCRIPTION

ddi_dma_setup( ) allocates resources for a memory object such that a device can perform DMA to or from that object.

A call to ddi_dma_setup( ) informs the system that device referred to by dip wishes to perform DMA to or from a memory object. The memory object, the device's DMA capabilities, the device driver's policy on whether to wait for resources, are all specified in the ddi_dma_req structure pointed to by dmareqp.

A successful call to ddi_dma_setup( ) fills in the value pointed to by handlep. This is an opaque object called a DMA handle. This handle is then used in subsequent DMA calls, until ddi_dma_free(9F) is called.

Again a DMA handle is opaque--drivers may not attempt to interpret its value. When a driver wants to enable its DMA engine, it must retrieve the appropriate address to supply to its DMA engine using a call to ddi_dma_htoc(9F), which takes a pointer to a DMA handle and returns the appropriate DMA address.

When DMA transfer completes, the driver should free up the the allocated DMA resources by calling ddi_dma_free( ).

RETURN VALUES

ddi_dma_setup( ) returns:

DDI_DMA_MAPPED

Successfully allocated resources for the object.

In the case of an advisory call, this indicates that

the request is legal.

DDI_DMA_PARTIAL_MAP

Successfully allocated resources for a part of

the object. This is acceptable when partial

transfers are allowed using a flag setting in the

ddi_dma_req structure (see ddi_dma_req(9S)

and ddi_dma_movwin(9F)).

DDI_DMA_NORESOURCES

When no resources are available.

DDI_DMA_NOMAPPING

The object cannot be reached by the device

requesting the resources.

DDI_DMA_TOOBIG

The object is too big and exceeds the available

resources. The maximum size varies depend-

ing on machine and configuration.

CONTEXT

ddi_dma_setup( ) can be called from user or interrupt context, except when the dmar_fp member of the ddi_dma_req structure pointed to by dmareqp is set to DDI_DMA_SLEEP, in which case it can be called from user context only.

SEE ALSO

ddi_dma_addr_setup(9F), ddi_dma_buf_setup(9F), ddi_dma_free(9F), ddi_dma_htoc(9F), ddi_dma_sync(9F), ddi_dma_req(9S)

Writing Device Drivers

NOTES

The construction of the ddi_dma_req structure is complicated. Use of the provided interface functions such as ddi_dma_buf_setup(9F) simplifies this task.