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, 2 insertions, 0 deletions

diff --git a/sys/dev/dpt/dpt_isa.c b/sys/dev/dpt/dpt_isa.c
index 708bb69..183b9fb 100644
--- a/sys/dev/dpt/dpt_isa.c
+++ b/sys/dev/dpt/dpt_isa.c
@@ -189,6 +189,8 @@ dpt_isa_attach (device_t dev)
 				/* nsegments */	~0,
 				/* maxsegsz  */	BUS_SPACE_MAXSIZE_32BIT,
 				/* flags     */	0,
+				/* lockfunc  */ busdma_lock_mutex,
+				/* lockarg   */ &Giant,
 				&dpt->parent_dmat) != 0) {
 		error = ENXIO;
 		goto bad;