SVR5

dma_swsetup(D3)

dma_swsetup -- program a DMA operation for a subsequent software request

Synopsis

   #include <sys/types.h>
   #include <sys/dma.h>
   #include <sys/ddi.h>
   
   int dma_swsetup(struct dma_cb *dmacbptr, int chan, uchar_t mode);

Description

dma_swsetup programs the ISA, EISA, or MCA DMA channel chan for the operation specified by the DMA command block whose address is given by dmacbptr.

Arguments

dmacbptr: Pointer to the DMA command block that specifies the DMA operation.
chan: DMA channel over which the operation is to take place.
mode: Specifies whether the caller is willing to sleep waiting to allocate desired DMA channel.

Return values

dma_swsetup returns the value TRUE on success and returns the value FALSE otherwise.

Usage

dma_swsetup does not initiate the DMA transfer. Instead, the transfer will be initiated by a subsequent request initiated via software by dma_swstart(D3). If dma_swsetup programs the operation successfully, it then calls the procedure specified by the proc field of the dma_cb(D4) structure. It passes as an argument the value in the ``procparms'' field. If proc is set to NULL, then no routine is called.

To program the operation, dma_swsetup requires exclusive use of the specified DMA channel. The caller may specify, via the mode argument, whether dma_swsetup should sleep waiting for a busy channel to become available. If the specified channel is in use and mode is set to DMA_SLEEP, then dma_swsetup will sleep until the channel becomes available for its use. Otherwise, if DMA_NOSLEEP is specified and the requested channel is not immediately available, dma_swsetup will not program the channel, but will simply return a value of FALSE.

Context and synchronization

If mode is set to DMA_NOSLEEP, non-blockable, initialization, or interrupt context.

If mode is set to DMA_SLEEP, user context. The driver must be in a legal context for the callback function being passed in with the dmacbptr argument.

Hardware applicability

PC-AT compatible platforms with ISA, EISA, or MCA buses

Version applicability

ddi: 1, 2, 3, 4, 5, 5mp, 6, 6mp, 7, 7mp, 7.1, 7.1mp, 8, 8mp

Future directions

This interface is expected to be replaced or modified in a future release.

References

dma_swstart(D3), dma_stop(D3), dma_cb(D4)

``DMA'' in HDK Technical Reference