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, 18 insertions, 1 deletions

diff --git a/sys/alpha/include/bus.h b/sys/alpha/include/bus.h
index 76f6477..582484c 100644
--- a/sys/alpha/include/bus.h
+++ b/sys/alpha/include/bus.h
@@ -523,6 +523,17 @@ typedef struct bus_dma_segment {
 typedef int bus_dma_filter_t(void *, bus_addr_t);
 
 /*
+ * A function that performs driver-specific syncronization on behalf of
+ * busdma.
+ */
+typedef enum {
+	BUS_DMA_LOCK	= 0x01,
+	BUS_DMA_UNLOCK	= 0x02,
+} bus_dma_lock_op_t;
+
+typedef void bus_dma_lock_t(void *, bus_dma_lock_op_t);
+
+/*
  * Allocate a device specific dma_tag encapsulating the constraints of
  * the parent tag in addition to other restrictions specified:
  *
@@ -547,7 +558,8 @@ int bus_dma_tag_create(bus_dma_tag_t parent, bus_size_t alignemnt,
 		       bus_size_t boundary, bus_addr_t lowaddr,
 		       bus_addr_t highaddr, bus_dma_filter_t *filtfunc,
 		       void *filtfuncarg, bus_size_t maxsize, int nsegments,
-		       bus_size_t maxsegsz, int flags, bus_dma_tag_t *dmat);
+		       bus_size_t maxsegsz, int flags, bus_dma_lock_t *lockfunc,
+		       void *lockfuncarg, bus_dma_tag_t *dmat);
 
 int bus_dma_tag_destroy(bus_dma_tag_t dmat);
 
@@ -629,4 +641,9 @@ void _bus_dmamap_unload(bus_dma_tag_t dmat, bus_dmamap_t map);
 	if ((dmamap) != NULL)				\
 		_bus_dmamap_unload(dmat, dmamap)
 
+/*
+ * Generic helper function for manipulating mutexes.
+ */
+void busdma_lock_mutex(void *arg, bus_dma_lock_op_t op);
+
 #endif /* _ALPHA_BUS_H_ */