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, 6 insertions, 0 deletions

diff --git a/sys/dev/ahb/ahb.c b/sys/dev/ahb/ahb.c
index a3902ae..2d2d373 100644
--- a/sys/dev/ahb/ahb.c
+++ b/sys/dev/ahb/ahb.c
@@ -33,6 +33,8 @@
 #include <sys/kernel.h>
 #include <sys/malloc.h>
 #include <sys/module.h>
+#include <sys/lock.h>
+#include <sys/mutex.h>
 #include <sys/bus.h>
 
 #include <machine/bus_pio.h>
@@ -303,6 +305,8 @@ ahbattach(device_t dev)
 				/* nsegments	*/ AHB_NSEG,
 				/* maxsegsz	*/ BUS_SPACE_MAXSIZE_32BIT,
 				/* flags	*/ BUS_DMA_ALLOCNOW,
+				/* lockfunc	*/ busdma_lock_mutex,
+				/* lockarg	*/ &Giant,
 				&ahb->buffer_dmat) != 0)
 		goto error_exit;
 
@@ -322,6 +326,8 @@ ahbattach(device_t dev)
 				/* nsegments	*/ 1,
 				/* maxsegsz	*/ BUS_SPACE_MAXSIZE_32BIT,
 				/* flags	*/ 0,
+				/* lockfunc	*/ busdma_lock_mutex,
+				/* lockarg	*/ &Giant,
 				&ahb->ecb_dmat) != 0)
 		goto error_exit;