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

ddi_dma_cookie - DMA address cookie

#include <sys/sunddi.h>

illumos DDI specific (illumos DDI).

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.


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.

pci(4), sbus(4), sysbus(4), 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

September 30, 1996 OmniOS