Copyright (c) 2006, Sun Microsystems, Inc.
The contents of this file are subject to the terms of the Common Development and Distribution License (the "License"). You may not use this file except in compliance with the License.
You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE or http://www.opensolaris.org/os/licensing. See the License for the specific language governing permissions and limitations under the License.
When distributing Covered Code, include this CDDL HEADER in each file and include the License file at usr/src/OPENSOLARIS.LICENSE. If applicable, add the following below this CDDL HEADER, with the fields enclosed by brackets "[]" replaced with your own identifying information: Portions Copyright [yyyy] [name of copyright owner]
#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);
This interface is obsolete. ddi_dma_getwin(9F) should be used instead.
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.
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_setup(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 window, 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.
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.
The ddi_dma_nextwin() function can be called from user, interrupt, or kernel context.
For an example see ddi_dma_segtocookie(9F).
See attributes(5) for a description of the following attributes:
| ATTRIBUTE TYPE | ATTRIBUTE VALUE |
| Stability Level | Obsolete |
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