Mega busdma API commit.

Add two new arguments to bus_dma_tag_create(): lockfunc and lockfuncarg.
Lockfunc allows a driver to provide a function for managing its locking
semantics while using busdma.  At the moment, this is used for the
asynchronous busdma_swi and callback mechanism.  Two lockfunc implementations
are provided: busdma_lock_mutex() performs standard mutex operations on the
mutex that is specified from lockfuncarg.  dftl_lock() is a panic
implementation and is defaulted to when NULL, NULL are passed to
bus_dma_tag_create().  The only time that NULL, NULL should ever be used is
when the driver ensures that bus_dmamap_load() will not be deferred.
Drivers that do not provide their own locking can pass
busdma_lock_mutex,&Giant args in order to preserve the former behaviour.

sparc64 and powerpc do not provide real busdma_swi functions, so this is
largely a noop on those platforms.  The busdma_swi on is64 is not properly
locked yet, so warnings will be emitted on this platform when busdma
callback deferrals happen.

If anyone gets panics or warnings from dflt_lock() being called, please
let me know right away.

Reviewed by:	tmm, gibbs

1 files changed, 3 insertions, 0 deletions

diff --git a/sys/dev/ciss/ciss.c b/sys/dev/ciss/ciss.c
index ed76fed..ba642de 100644
--- a/sys/dev/ciss/ciss.c
+++ b/sys/dev/ciss/ciss.c
@@ -600,6 +600,7 @@ ciss_init_pci(struct ciss_softc *sc)
 			   MAXBSIZE, CISS_COMMAND_SG_LENGTH,	/* maxsize, nsegments */
 			   BUS_SPACE_MAXSIZE_32BIT,	/* maxsegsize */
 			   BUS_DMA_ALLOCNOW,		/* flags */
+			   NULL, NULL,			/* lockfunc, lockarg */
 			   &sc->ciss_parent_dmat)) {
 	ciss_printf(sc, "can't allocate parent DMA tag\n");
 	return(ENOMEM);
@@ -617,6 +618,7 @@ ciss_init_pci(struct ciss_softc *sc)
 			   MAXBSIZE, CISS_COMMAND_SG_LENGTH,	/* maxsize, nsegments */
 			   BUS_SPACE_MAXSIZE_32BIT,	/* maxsegsize */
 			   0,				/* flags */
+			   busdma_lock_mutex, &Giant,	/* lockfunc, lockarg */
 			   &sc->ciss_buffer_dmat)) {
 	ciss_printf(sc, "can't allocate buffer DMA tag\n");
 	return(ENOMEM);
@@ -745,6 +747,7 @@ ciss_init_requests(struct ciss_softc *sc)
 			   sc->ciss_max_requests, 1,	/* maxsize, nsegments */
 			   BUS_SPACE_MAXSIZE_32BIT,	/* maxsegsize */
 			   0,				/* flags */
+			   busdma_lock_mutex, &Giant,	/* lockfunc, lockarg */
 			   &sc->ciss_command_dmat)) {
 	ciss_printf(sc, "can't allocate command DMA tag\n");
 	return(ENOMEM);