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/aha/aha_mca.c b/sys/dev/aha/aha_mca.c
index 761504e..10ce088 100644
--- a/sys/dev/aha/aha_mca.c
+++ b/sys/dev/aha/aha_mca.c
@@ -31,6 +31,8 @@
 #include <sys/types.h>
 #include <sys/param.h>
 #include <sys/kernel.h>
+#include <sys/lock.h>
+#include <sys/mutex.h>
 
 #include <sys/module.h>
 #include <sys/bus.h>
@@ -184,6 +186,8 @@ aha_mca_attach (device_t dev)
 				/* nsegments	*/ ~0,
 				/* maxsegsz	*/ BUS_SPACE_MAXSIZE_24BIT,
 				/* flags	*/ 0,
+				/* lockfunc	*/ busdma_lock_mutex,
+				/* lockarg	*/ &Giant,
 				&sc->parent_dmat);
 	if (error) {
 		device_printf(dev, "bus_dma_tag_create() failed!\n");