ddi_dma_getwin(9F) Kernel Functions for Drivers ddi_dma_getwin(9F)NAMEddi_dma_getwin - activate a new DMA window
SYNOPSIS
#include <sys/ddi.h>
#include <sys/sunddi.h>
int ddi_dma_getwin(ddi_dma_handle_t handle, uint_t win, off_t *offp,
size_t *lenp, ddi_dma_cookie_t *cookiep, uint_t *ccountp);
INTERFACE LEVEL
Solaris DDI specific (Solaris DDI).
PARAMETERS
handle The DMA handle previously allocated by a call to
ddi_dma_alloc_handle(9F).
win Number of the window to activate.
offp Pointer to an offset. Upon a successful return, offp
will contain the new offset indicating the
beginning of the window within the object.
lenp Upon a successful return, lenp will contain the size,
in bytes, of the current window.
cookiep A pointer to the first ddi_dma_cookie(9S) structure.
ccountp Upon a successful return, ccountp will contain the
number of cookies for this DMA window.
DESCRIPTIONddi_dma_getwin() activates a new DMA window. If a DMA resource allo‐
cation request returns DDI_DMA_PARTIAL_MAP indicating that resources
for less than the entire object were allocated, the current DMA window
can be changed by a call to ddi_dma_getwin().
The caller must first determine the number of DMA windows, N, using
ddi_dma_numwin(9F). ddi_dma_getwin() takes a DMA window number from
the range [0..N-1] as the parameter win and makes it the current DMA
window.
ddi_dma_getwin() fills in the first DMA cookie pointed to by cookiep
with the appropriate address, length, and bus type. *ccountp is set to
the number of DMA cookies representing this DMA object. Subsequent DMA
cookies must be retrieved using ddi_dma_nextcookie(9F).
ddi_dma_getwin() takes care of underlying resource synchronizations
required to shift the window. However accessing the data prior to or
after moving the window requires further synchronization steps using
ddi_dma_sync(9F).
ddi_dma_getwin() is normally called from an interrupt routine. The
first invocation of the DMA engine is done from the driver. All subse‐
quent invocations of the DMA engine are done from the interrupt rou‐
tine. The interrupt routine checks to see if the request has been com‐
pleted. If it has, the interrupt routine returns without invoking
another DMA transfer. Otherwise, it calls ddi_dma_getwin() to shift
the current window and start another DMA transfer.
RETURN VALUESddi_dma_getwin() returns:
DDI_SUCCESS Resources for the specified DMA window are allocated.
DDI_FAILURE win is not a valid window index.
CONTEXTddi_dma_getwin() can be called from user, kernel, or interrupt context.
SEE ALSOddi_dma_addr_bind_handle(9F), ddi_dma_alloc_handle(9F),
ddi_dma_buf_bind_handle(9F), ddi_dma_nextcookie(9F),
ddi_dma_numwin(9F), ddi_dma_sync(9F), ddi_dma_unbind_handle(9F),
ddi_dma_cookie(9S)
Writing Device Drivers
SunOS 5.10 15 Nov 1996 ddi_dma_getwin(9F)
