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

4 files changed, 73 insertions, 5 deletions

diff --git a/sys/sparc64/include/bus.h b/sys/sparc64/include/bus.h
index 2a3e5a6..4e0c2b4 100644
--- a/sys/sparc64/include/bus.h
+++ b/sys/sparc64/include/bus.h
@@ -957,6 +957,17 @@ typedef void bus_dmamap_callback_t(void *, bus_dma_segment_t *, int, int);
 typedef void bus_dmamap_callback2_t(void *, bus_dma_segment_t *, int, bus_size_t, int);
 
 /*
+ * 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);
+  
+/*
  * Method table for a bus_dma_tag.
  */
 struct bus_dma_methods {
@@ -996,13 +1007,15 @@ struct bus_dma_tag {
 	int		dt_flags;
 	int		dt_ref_count;
 	int		dt_map_count;
+	bus_dma_lock_t	*dt_lockfunc;
+	void *		*dt_lockfuncarg;
 
 	struct bus_dma_methods	*dt_mt;
 };
 
 int bus_dma_tag_create(bus_dma_tag_t, bus_size_t, bus_size_t, bus_addr_t,
     bus_addr_t, bus_dma_filter_t *, void *, bus_size_t, int, bus_size_t,
-    int, bus_dma_tag_t *);
+    int, bus_dma_lock_t *, void *, bus_dma_tag_t *);
 
 int bus_dma_tag_destroy(bus_dma_tag_t);
 
@@ -1025,4 +1038,8 @@ int bus_dma_tag_destroy(bus_dma_tag_t);
 #define	bus_dmamem_free(t, v, m)					\
 	((t)->dt_mt->dm_dmamem_free((t), (v), (m)))
 
+/*
+ * Generic helper function for manipulating mutexes.
+ */
+void busdma_lock_mutex(void *arg, bus_dma_lock_op_t op);
 #endif /* !_MACHINE_BUS_H_ */
diff --git a/sys/sparc64/pci/psycho.c b/sys/sparc64/pci/psycho.c
index a1d7fee..bf76c3c 100644
--- a/sys/sparc64/pci/psycho.c
+++ b/sys/sparc64/pci/psycho.c
@@ -553,7 +553,7 @@ psycho_attach(device_t dev)
 	sc->sc_iot = psycho_alloc_bus_tag(sc, PCI_IO_BUS_SPACE);
 	sc->sc_cfgt = psycho_alloc_bus_tag(sc, PCI_CONFIG_BUS_SPACE);
 	if (bus_dma_tag_create(sc->sc_dmatag, 8, 1, 0, 0x3ffffffff, NULL, NULL,
-	    0x3ffffffff, 0xff, 0xffffffff, 0, &sc->sc_dmat) != 0)
+	    0x3ffffffff, 0xff, 0xffffffff, 0, NULL, NULL, &sc->sc_dmat) != 0)
 		panic("psycho_attach: bus_dma_tag_create failed");
 	/* Customize the tag. */
 	sc->sc_dmat->dt_cookie = sc->sc_is;
diff --git a/sys/sparc64/sbus/sbus.c b/sys/sparc64/sbus/sbus.c
index 22a0aeb..028933e 100644
--- a/sys/sparc64/sbus/sbus.c
+++ b/sys/sparc64/sbus/sbus.c
@@ -393,7 +393,7 @@ sbus_probe(device_t dev)
 	/* Create the DMA tag. */
 	sc->sc_dmatag = nexus_get_dmatag(dev);
 	if (bus_dma_tag_create(sc->sc_dmatag, 8, 1, 0, 0x3ffffffff, NULL, NULL,
-	    0x3ffffffff, 0xff, 0xffffffff, 0, &sc->sc_cdmatag) != 0)
+	    0x3ffffffff, 0xff, 0xffffffff, 0, NULL, NULL, &sc->sc_cdmatag) != 0)
 		panic("bus_dma_tag_create failed");
 	/* Customize the tag. */
 	sc->sc_cdmatag->dt_cookie = &sc->sc_is;
diff --git a/sys/sparc64/sparc64/bus_machdep.c b/sys/sparc64/sparc64/bus_machdep.c
index 90d6ffd..b9fa29e 100644
--- a/sys/sparc64/sparc64/bus_machdep.c
+++ b/sys/sparc64/sparc64/bus_machdep.c
@@ -155,7 +155,47 @@ int bus_stream_asi[] = {
 };
 
 /*
- * Since there is now way for a device to obtain a dma tag from its parent
+ * Convenience function for manipulating driver locks from busdma (during
+ * busdma_swi, for example).  Drivers that don't provide their own locks
+ * should specify &Giant to dmat->lockfuncarg.  Drivers that use their own
+ * non-mutex locking scheme don't have to use this at all.
+ */
+void
+busdma_lock_mutex(void *arg, bus_dma_lock_op_t op)
+{
+	struct mtx *dmtx;
+
+	dmtx = (struct mtx *)arg;
+	switch (op) {
+	case BUS_DMA_LOCK:
+		mtx_lock(dmtx);
+		break;
+	case BUS_DMA_UNLOCK:
+		mtx_unlock(dmtx);
+		break;
+	default:
+		panic("Unknown operation 0x%x for busdma_lock_mutex!", op);
+	}
+}
+
+/*
+ * dflt_lock should never get called.  It gets put into the dma tag when
+ * lockfunc == NULL, which is only valid if the maps that are associated
+ * with the tag are meant to never be defered.
+ * XXX Should have a way to identify which driver is responsible here.
+ */
+static void
+dflt_lock(void *arg, bus_dma_lock_op_t op)
+{
+#ifdef INVARIANTS
+	panic("driver error: busdma dflt_lock called");
+#else
+	printf("DRIVER_ERROR: busdma dflt_lock called\n");
+#endif
+}
+
+/*
+ * Since there is no way for a device to obtain a dma tag from its parent
  * we use this kluge to handle different the different supported bus systems.
  * The sparc64_root_dma_tag is used as parent for tags that have none, so that
  * the correct methods will be used.
@@ -169,7 +209,8 @@ int
 bus_dma_tag_create(bus_dma_tag_t parent, bus_size_t alignment,
     bus_size_t boundary, bus_addr_t lowaddr, bus_addr_t highaddr,
     bus_dma_filter_t *filter, void *filterarg, bus_size_t maxsize,
-    int nsegments, bus_size_t maxsegsz, int flags, bus_dma_tag_t *dmat)
+    int nsegments, bus_size_t maxsegsz, int flags, bus_dma_lock_t *lockfunc,
+    void *lockfuncarg, bus_dma_tag_t *dmat)
 {
 	bus_dma_tag_t impptag;
 	bus_dma_tag_t newtag;
@@ -204,6 +245,14 @@ bus_dma_tag_create(bus_dma_tag_t parent, bus_size_t alignment,
 	newtag->dt_ref_count = 1; /* Count ourselves */
 	newtag->dt_map_count = 0;
 
+	if (lockfunc != NULL) {
+		newtag->dt_lockfunc = lockfunc;
+		newtag->dt_lockfuncarg = lockfuncarg;
+	} else {
+		newtag->dt_lockfunc = dflt_lock;
+		newtag->dt_lockfuncarg = NULL;
+	}
+       
 	/* Take into account any restrictions imposed by our parent tag */
 	if (parent != NULL) {
 		newtag->dt_lowaddr = ulmin(parent->dt_lowaddr,
@@ -630,6 +679,8 @@ struct bus_dma_tag nexus_dmatag = {
 	0,
 	0,
 	0,
+	NULL,
+	NULL,
 	&nexus_dma_methods,
 };