DDI_DMA_COOKIE(9S) Data Structures for Drivers DDI_DMA_COOKIE(9S)

NAME

ddi_dma_cookie - DMA address cookie

SYNOPSIS

#include <sys/sunddi.h>

INTERFACE LEVEL

illumos DDI specific (illumos DDI).

DESCRIPTION

The ddi_dma_cookie_t structure contains DMA address information
required to program a DMA engine. The structure is filled in by a
call to ddi_dma_getwin(9F), ddi_dma_addr_bind_handle(9F), or
ddi_dma_buf_bind_handle(9F), to get device-specific DMA transfer
information for a DMA request or a DMA window.

STRUCTURE MEMBERS

typedef struct {
union {
uint64_t _dmac_ll; /* 64 bit DMA add. */
uint32_t _dmac_la[2]; /* 2 x 32 bit add. */
} _dmu;
size_t dmac_size; /* DMA cookie size */
uint_t dmac_type; /* bus spec. type bits */
} ddi_dma_cookie_t;


You can access the DMA address through the #defines: dmac_address for
32-bit addresses and dmac_laddress for 64-bit addresses. These macros
are defined as follows:

#define dmac_laddress _dmu._dmac_ll
#ifdef _LONG_LONG_HTOL
#define dmac_notused _dmu._dmac_la[0]
#define dmac_address _dmu._dmac_la[1]
#else
#define dmac_address _dmu._dmac_la[0]
#define dmac_notused _dmu._dmac_la[1]
#endif


dmac_laddress specifies a 64-bit I/O address appropriate for
programming the device's DMA engine. If a device has a 64-bit DMA
address register a driver should use this field to program the DMA
engine. dmac_address specifies a 32-bit I/O address. It should be
used for devices that have a 32-bit DMA address register. The I/O
address range that the device can address and other DMA attributes
have to be specified in a ddi_dma_attr(9S) structure.


dmac_size describes the length of the transfer in bytes.


dmac_type contains bus-specific type bits, if appropriate. For
example, a device on a PCI bus has PCI address modifier bits placed
here.

SEE ALSO

pci(5), sysbus(5), ddi_dma_addr_bind_handle(9F),
ddi_dma_buf_bind_handle(9F), ddi_dma_getwin(9F),
ddi_dma_nextcookie(9F), ddi_dma_attr(9S)


Writing Device Drivers

March 6, 2023 DDI_DMA_COOKIE(9S)