opensolaris man page for ddi_dma_nextwin

ddi_dma_nextwin(9F)					   Kernel Functions for Drivers 				       ddi_dma_nextwin(9F)

NAME
       ddi_dma_nextwin - get next DMA window

SYNOPSIS
       #include <sys/ddi.h>
       #include <sys/sunddi.h>

       int ddi_dma_nextwin(ddi_dma_handle_t handle, ddi_dma_win_t win,
	    ddi_dma_win_t *nwin);

INTERFACE LEVEL
       This interface is obsolete. ddi_dma_getwin(9F) should be used instead.

PARAMETERS
       handle	 A DMA handle.

       win	 The current DMA window or NULL.

       nwin	 A pointer to the next DMA window to be filled in. If win is NULL, a pointer to the first window within the object is returned.

DESCRIPTION
       The  ddi_dma_nextwin()  function  shifts the current DMA window win within the object referred to by handle to the next DMA window nwin. If
       the current window is NULL, the first window within the object is returned. A DMA window is a portion of a  DMA	object	or  might  be  the
       entire object. A DMA window has system resources allocated to it and is prepared to accept data transfers. Examples of system resources are
       DVMA mapping resources and intermediate transfer buffer resources.

       All DMA objects require a window. If the DMA window represents the whole DMA object it has system resources allocated for the  entire  data
       transfer.  However,  if the system is unable to setup the entire DMA object due to system resource limitations, the driver writer may allow
       the system to allocate system resources for less than the entire DMA object. This can be accomplished  by  specifying  the  DDI_DMA_PARTIAL
       flag  as a parameter to ddi_dma_buf_setup(9F) or ddi_dma_addr_setup(9F) or as part of a ddi_dma_req(9S) structure in a call to ddi_dma_set-
       up(9F).

       Only the window that has resources allocated is valid per object at any one time. The currently valid window  is  the  one  that  was  most
       recently returned from ddi_dma_nextwin(). Furthermore, because a call to ddi_dma_nextwin() will reallocate system resources to the new win-
       dow, the previous window will become invalid. It is a severe error to call ddi_dma_nextwin() before any transfers into the  current  window
       are complete.

       The  ddi_dma_nextwin()  function  takes	care  of  underlying memory synchronizations required to shift the window. However, if you want to
       access the data before or after moving the window, further synchronizations using ddi_dma_sync(9F) are required.

RETURN VALUES
       The ddi_dma_nextwin() function returns:

       DDI_SUCCESS	Successfully filled in the next window pointer.

       DDI_DMA_DONE	There is no next window. The current window is the final window within the specified object.

       DDI_DMA_STALE	win does not refer to the currently active window.

CONTEXT
       The ddi_dma_nextwin() function can be called from user, interrupt, or kernel context.

EXAMPLES
       For an example see ddi_dma_segtocookie(9F).

ATTRIBUTES
       See attributes(5) for a description of the following attributes:

       +-----------------------------+-----------------------------+
       |      ATTRIBUTE TYPE	     |	    ATTRIBUTE VALUE	   |
       +-----------------------------+-----------------------------+
       |Stability Level 	     |Obsolete			   |
       +-----------------------------+-----------------------------+

SEE ALSO
       attributes(5),	ddi_dma_addr_setup(9F),   ddi_dma_buf_setup(9F),   ddi_dma_getwin(9F),	  ddi_dma_nextseg(9F),	  ddi_dma_segtocookie(9F),
       ddi_dma_sync(9F), ddi_dma_req(9S)

       Writing Device Drivers

SunOS 5.11							    16 Jan 2006 					       ddi_dma_nextwin(9F)