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, 7 insertions, 1 deletions

diff --git a/sys/dev/amd/amd.c b/sys/dev/amd/amd.c
index 6267ce0..fe398ad 100644
--- a/sys/dev/amd/amd.c
+++ b/sys/dev/amd/amd.c
@@ -55,6 +55,8 @@
 #include <sys/systm.h>
 #include <sys/queue.h>
 #include <sys/kernel.h>
+#include <sys/lock.h>
+#include <sys/mutex.h>
 
 #include <vm/vm.h>
 #include <vm/pmap.h>
@@ -2290,6 +2292,8 @@ amd_init(device_t dev)
 			       /*maxsize*/MAXBSIZE, /*nsegments*/AMD_NSEG,
 			       /*maxsegsz*/AMD_MAXTRANSFER_SIZE,
 			       /*flags*/BUS_DMA_ALLOCNOW,
+			       /*lockfunc*/busdma_lock_mutex,
+			       /*lockarg*/&Giant,
 			       &amd->buffer_dmat) != 0) {
 		if (bootverbose)
 			printf("amd_init: bus_dma_tag_create failure!\n");
@@ -2305,7 +2309,9 @@ amd_init(device_t dev)
 			       sizeof(struct scsi_sense_data) * MAX_SRB_CNT,
 			       /*nsegments*/1,
 			       /*maxsegsz*/AMD_MAXTRANSFER_SIZE,
-			       /*flags*/0, &amd->sense_dmat) != 0) {
+			       /*flags*/0,
+			       /*lockfunc*/busdma_lock_mutex,
+			       /*lockarg*/&Giant, &amd->sense_dmat) != 0) {
 		if (bootverbose)
 			device_printf(dev, "cannot create sense buffer dmat\n");
 		return (ENXIO);