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, 4 insertions, 0 deletions

diff --git a/sys/dev/twe/twe_freebsd.c b/sys/dev/twe/twe_freebsd.c
index 1a41f16..efe63da 100644
--- a/sys/dev/twe/twe_freebsd.c
+++ b/sys/dev/twe/twe_freebsd.c
@@ -233,6 +233,8 @@ twe_attach(device_t dev)
 			   MAXBSIZE, TWE_MAX_SGL_LENGTH,	/* maxsize, nsegments */
 			   BUS_SPACE_MAXSIZE_32BIT,		/* maxsegsize */
 			   BUS_DMA_ALLOCNOW,			/* flags */
+			   NULL,				/* lockfunc */
+			   NULL,				/* lockarg */
 			   &sc->twe_parent_dmat)) {
 	twe_printf(sc, "can't allocate parent DMA tag\n");
 	twe_free(sc);
@@ -265,6 +267,8 @@ twe_attach(device_t dev)
 			   MAXBSIZE, TWE_MAX_SGL_LENGTH,/* maxsize, nsegments */
 			   BUS_SPACE_MAXSIZE_32BIT,	/* maxsegsize */
 			   0,				/* flags */
+			   busdma_lock_mutex,			/* lockfunc */
+			   &Giant,				/* lockarg */
 			   &sc->twe_buffer_dmat)) {
 	twe_printf(sc, "can't allocate data buffer DMA tag\n");
 	twe_free(sc);