Implement bus_dmamem_alloc_size() and bus_dmamem_free_size() as

counterparts to bus_dmamem_alloc() and bus_dmamem_free().  This allows
the caller to specify the size of the allocation instead of it defaulting
to the max_size field of the busdma tag.

This is intended to aid in converting drivers to busdma.  Lots of
hardware cannot understand scatter/gather lists, which forces the
driver to copy the i/o buffers to a single contiguous region
before sending it to the hardware.  Without these new methods, this
would require a new busdma tag for each operation, or a complex
internal allocator/cache for each driver.

Allocations greater than PAGE_SIZE are rounded up to the next
PAGE_SIZE by contigmalloc(), so this is not suitable for multiple
static allocations that would be better served by a single
fixed-length subdivided allocation.

Reviewed by:	jake (sparc64)

sys/alpha/alpha/busdma_machdep.c

@@ -350,14 +350,18 @@ bus_dmamap_destroy(bus_dma_tag_t dmat, bus_dmamap_t map)
  * A dmamap to for use with dmamap_load is also allocated.
  */
 int
-bus_dmamem_alloc(bus_dma_tag_t dmat, void** vaddr, int flags,
+bus_dmamem_alloc_size(bus_dma_tag_t dmat, void** vaddr, int flags,
-		 bus_dmamap_t *mapp)
+		      bus_dmamap_t *mapp, bus_size_t size)
 {
+
+	if (size > dmat->maxsize)
+		return (ENOMEM);
+
 	/* If we succeed, no mapping/bouncing will be required */
 	*mapp = &nobounce_dmamap;
 
-	if ((dmat->maxsize <= PAGE_SIZE) && dmat->lowaddr >= ptoa(Maxmem)) {
+	if ((size <= PAGE_SIZE) && dmat->lowaddr >= ptoa(Maxmem)) {
-		*vaddr = malloc(dmat->maxsize, M_DEVBUF,
+		*vaddr = malloc(size, M_DEVBUF,
 				(flags & BUS_DMA_NOWAIT) ? M_NOWAIT : 0);
 	} else {
 		/*
@@ -365,7 +369,7 @@ bus_dmamem_alloc(bus_dma_tag_t dmat, void** vaddr, int flags,
 		 *     and handles multi-seg allocations.  Nobody is doing
 		 *     multi-seg allocations yet though.
 		 */
-		*vaddr = contigmalloc(dmat->maxsize, M_DEVBUF,
+		*vaddr = contigmalloc(size, M_DEVBUF,
 		    (flags & BUS_DMA_NOWAIT) ? M_NOWAIT : 0,
 		    0ul, dmat->lowaddr, dmat->alignment? dmat->alignment : 1ul,
 		    dmat->boundary);
@@ -375,12 +379,20 @@ bus_dmamem_alloc(bus_dma_tag_t dmat, void** vaddr, int flags,
 	return (0);
 }
 
+int
+bus_dmamem_alloc(bus_dma_tag_t dmat, void** vaddr, int flags,
+		 bus_dmamap_t *mapp)
+{
+	return (bus_dmamem_alloc_size(dmat, vaddr, flags, mapp, dmat->maxsize));
+}
+
 /*
  * Free a piece of memory and it's allociated dmamap, that was allocated
  * via bus_dmamem_alloc.
  */
 void
-bus_dmamem_free(bus_dma_tag_t dmat, void *vaddr, bus_dmamap_t map)
+bus_dmamem_free_size(bus_dma_tag_t dmat, void *vaddr, bus_dmamap_t map,
+		     bus_size_t size)
 {
 	/*
 	 * dmamem does not need to be bounced, so the map should be
@@ -388,10 +400,16 @@ bus_dmamem_free(bus_dma_tag_t dmat, void *vaddr, bus_dmamap_t map)
 	 */
 	if (map != &nobounce_dmamap)
 		panic("bus_dmamem_free: Invalid map freed\n");
-	if ((dmat->maxsize <= PAGE_SIZE) && dmat->lowaddr >= ptoa(Maxmem))
+	if ((size <= PAGE_SIZE) && dmat->lowaddr >= ptoa(Maxmem))
 		free(vaddr, M_DEVBUF);
 	else
-		contigfree(vaddr, dmat->maxsize, M_DEVBUF);
+		contigfree(vaddr, size, M_DEVBUF);
+}
+
+void
+bus_dmamem_free(bus_dma_tag_t dmat, void *vaddr, bus_dmamap_t map)
+{
+	bus_dmamem_free_size(dmat, vaddr, map, dmat->maxsize);
 }
 
 #define BUS_DMAMAP_NSEGS ((BUS_SPACE_MAXSIZE / PAGE_SIZE) + 1)

sys/alpha/include/bus.h

@@ -571,6 +571,9 @@ int bus_dmamap_destroy(bus_dma_tag_t dmat, bus_dmamap_t map);
  * bus device space based on the constraints lited in the dma tag.
  * A dmamap to for use with dmamap_load is also allocated.
  */
+int bus_dmamem_alloc_size(bus_dma_tag_t dmat, void** vaddr, int flags,
+			  bus_dmamap_t *mapp, bus_size_t size);
+
 int bus_dmamem_alloc(bus_dma_tag_t dmat, void** vaddr, int flags,
 		     bus_dmamap_t *mapp);
 
@@ -578,6 +581,9 @@ int bus_dmamem_alloc(bus_dma_tag_t dmat, void** vaddr, int flags,
  * Free a piece of memory and it's allociated dmamap, that was allocated
  * via bus_dmamem_alloc.
  */
+void bus_dmamem_free_size(bus_dma_tag_t dmat, void *vaddr, bus_dmamap_t map,
+			  bus_size_t size);
+
 void bus_dmamem_free(bus_dma_tag_t dmat, void *vaddr, bus_dmamap_t map);
 
 /*

sys/amd64/amd64/busdma_machdep.c

@@ -331,14 +331,18 @@ bus_dmamap_destroy(bus_dma_tag_t dmat, bus_dmamap_t map)
  * A dmamap to for use with dmamap_load is also allocated.
  */
 int
-bus_dmamem_alloc(bus_dma_tag_t dmat, void** vaddr, int flags,
+bus_dmamem_alloc_size(bus_dma_tag_t dmat, void** vaddr, int flags,
-		 bus_dmamap_t *mapp)
+		      bus_dmamap_t *mapp, bus_size_t size)
 {
+
+	if (size > dmat->maxsize)
+		return (ENOMEM);
+
 	/* If we succeed, no mapping/bouncing will be required */
 	*mapp = NULL;
 
-	if ((dmat->maxsize <= PAGE_SIZE) && dmat->lowaddr >= ptoa(Maxmem)) {
+	if ((size <= PAGE_SIZE) && dmat->lowaddr >= ptoa(Maxmem)) {
-		*vaddr = malloc(dmat->maxsize, M_DEVBUF,
+		*vaddr = malloc(size, M_DEVBUF,
 				(flags & BUS_DMA_NOWAIT) ? M_NOWAIT : 0);
 	} else {
 		/*
@@ -346,7 +350,7 @@ bus_dmamem_alloc(bus_dma_tag_t dmat, void** vaddr, int flags,
 		 *     and handles multi-seg allocations.  Nobody is doing
 		 *     multi-seg allocations yet though.
 		 */
-		*vaddr = contigmalloc(dmat->maxsize, M_DEVBUF,
+		*vaddr = contigmalloc(size, M_DEVBUF,
 		    (flags & BUS_DMA_NOWAIT) ? M_NOWAIT : 0,
 		    0ul, dmat->lowaddr, dmat->alignment? dmat->alignment : 1ul,
 		    dmat->boundary);
@@ -356,12 +360,20 @@ bus_dmamem_alloc(bus_dma_tag_t dmat, void** vaddr, int flags,
 	return (0);
 }
 
+int
+bus_dmamem_alloc(bus_dma_tag_t dmat, void** vaddr, int flags,
+		 bus_dmamap_t *mapp)
+{
+	return (bus_dmamem_alloc_size(dmat, vaddr, flags, mapp, dmat->maxsize));
+}
+
 /*
  * Free a piece of memory and it's allociated dmamap, that was allocated
  * via bus_dmamem_alloc.  Make the same choice for free/contigfree.
  */
 void
-bus_dmamem_free(bus_dma_tag_t dmat, void *vaddr, bus_dmamap_t map)
+bus_dmamem_free_size(bus_dma_tag_t dmat, void *vaddr, bus_dmamap_t map,
+		     bus_size_t size)
 {
 	/*
 	 * dmamem does not need to be bounced, so the map should be
@@ -369,10 +381,16 @@ bus_dmamem_free(bus_dma_tag_t dmat, void *vaddr, bus_dmamap_t map)
 	 */
 	if (map != NULL)
 		panic("bus_dmamem_free: Invalid map freed\n");
-	if ((dmat->maxsize <= PAGE_SIZE) && dmat->lowaddr >= ptoa(Maxmem))
+	if ((size <= PAGE_SIZE) && dmat->lowaddr >= ptoa(Maxmem))
 		free(vaddr, M_DEVBUF);
 	else
-		contigfree(vaddr, dmat->maxsize, M_DEVBUF);
+		contigfree(vaddr, size, M_DEVBUF);
+}
+
+void
+bus_dmamem_free(bus_dma_tag_t dmat, void *vaddr, bus_dmamap_t map)
+{
+	bus_dmamem_free_size(dmat, vaddr, map, dmat->maxsize);
 }
 
 #define BUS_DMAMAP_NSEGS ((BUS_SPACE_MAXSIZE / PAGE_SIZE) + 1)

sys/amd64/include/bus_dma.h

@@ -180,6 +180,9 @@ int bus_dmamap_destroy(bus_dma_tag_t dmat, bus_dmamap_t map);
  * bus device space based on the constraints lited in the dma tag.
  * A dmamap to for use with dmamap_load is also allocated.
  */
+int bus_dmamem_alloc_size(bus_dma_tag_t dmat, void** vaddr, int flags,
+			  bus_dmamap_t *mapp, bus_size_t size);
+
 int bus_dmamem_alloc(bus_dma_tag_t dmat, void** vaddr, int flags,
 		     bus_dmamap_t *mapp);
 
@@ -187,6 +190,9 @@ int bus_dmamem_alloc(bus_dma_tag_t dmat, void** vaddr, int flags,
  * Free a piece of memory and it's allociated dmamap, that was allocated
  * via bus_dmamem_alloc.
  */
+void bus_dmamem_free_size(bus_dma_tag_t dmat, void *vaddr, bus_dmamap_t map,
+			  bus_size_t size);
+
 void bus_dmamem_free(bus_dma_tag_t dmat, void *vaddr, bus_dmamap_t map);
 
 /*

sys/i386/i386/busdma_machdep.c

@@ -331,14 +331,18 @@ bus_dmamap_destroy(bus_dma_tag_t dmat, bus_dmamap_t map)
  * A dmamap to for use with dmamap_load is also allocated.
  */
 int
-bus_dmamem_alloc(bus_dma_tag_t dmat, void** vaddr, int flags,
+bus_dmamem_alloc_size(bus_dma_tag_t dmat, void** vaddr, int flags,
-		 bus_dmamap_t *mapp)
+		      bus_dmamap_t *mapp, bus_size_t size)
 {
+
+	if (size > dmat->maxsize)
+		return (ENOMEM);
+
 	/* If we succeed, no mapping/bouncing will be required */
 	*mapp = NULL;
 
-	if ((dmat->maxsize <= PAGE_SIZE) && dmat->lowaddr >= ptoa(Maxmem)) {
+	if ((size <= PAGE_SIZE) && dmat->lowaddr >= ptoa(Maxmem)) {
-		*vaddr = malloc(dmat->maxsize, M_DEVBUF,
+		*vaddr = malloc(size, M_DEVBUF,
 				(flags & BUS_DMA_NOWAIT) ? M_NOWAIT : 0);
 	} else {
 		/*
@@ -346,7 +350,7 @@ bus_dmamem_alloc(bus_dma_tag_t dmat, void** vaddr, int flags,
 		 *     and handles multi-seg allocations.  Nobody is doing
 		 *     multi-seg allocations yet though.
 		 */
-		*vaddr = contigmalloc(dmat->maxsize, M_DEVBUF,
+		*vaddr = contigmalloc(size, M_DEVBUF,
 		    (flags & BUS_DMA_NOWAIT) ? M_NOWAIT : 0,
 		    0ul, dmat->lowaddr, dmat->alignment? dmat->alignment : 1ul,
 		    dmat->boundary);
@@ -356,12 +360,20 @@ bus_dmamem_alloc(bus_dma_tag_t dmat, void** vaddr, int flags,
 	return (0);
 }
 
+int
+bus_dmamem_alloc(bus_dma_tag_t dmat, void** vaddr, int flags,
+		 bus_dmamap_t *mapp)
+{
+	return (bus_dmamem_alloc_size(dmat, vaddr, flags, mapp, dmat->maxsize));
+}
+
 /*
  * Free a piece of memory and it's allociated dmamap, that was allocated
  * via bus_dmamem_alloc.  Make the same choice for free/contigfree.
  */
 void
-bus_dmamem_free(bus_dma_tag_t dmat, void *vaddr, bus_dmamap_t map)
+bus_dmamem_free_size(bus_dma_tag_t dmat, void *vaddr, bus_dmamap_t map,
+		     bus_size_t size)
 {
 	/*
 	 * dmamem does not need to be bounced, so the map should be
@@ -369,10 +381,16 @@ bus_dmamem_free(bus_dma_tag_t dmat, void *vaddr, bus_dmamap_t map)
 	 */
 	if (map != NULL)
 		panic("bus_dmamem_free: Invalid map freed\n");
-	if ((dmat->maxsize <= PAGE_SIZE) && dmat->lowaddr >= ptoa(Maxmem))
+	if ((size <= PAGE_SIZE) && dmat->lowaddr >= ptoa(Maxmem))
 		free(vaddr, M_DEVBUF);
 	else
-		contigfree(vaddr, dmat->maxsize, M_DEVBUF);
+		contigfree(vaddr, size, M_DEVBUF);
+}
+
+void
+bus_dmamem_free(bus_dma_tag_t dmat, void *vaddr, bus_dmamap_t map)
+{
+	bus_dmamem_free_size(dmat, vaddr, map, dmat->maxsize);
 }
 
 #define BUS_DMAMAP_NSEGS ((BUS_SPACE_MAXSIZE / PAGE_SIZE) + 1)

sys/i386/include/bus_dma.h

@@ -180,6 +180,9 @@ int bus_dmamap_destroy(bus_dma_tag_t dmat, bus_dmamap_t map);
  * bus device space based on the constraints lited in the dma tag.
  * A dmamap to for use with dmamap_load is also allocated.
  */
+int bus_dmamem_alloc_size(bus_dma_tag_t dmat, void** vaddr, int flags,
+			  bus_dmamap_t *mapp, bus_size_t size);
+
 int bus_dmamem_alloc(bus_dma_tag_t dmat, void** vaddr, int flags,
 		     bus_dmamap_t *mapp);
 
@@ -187,6 +190,9 @@ int bus_dmamem_alloc(bus_dma_tag_t dmat, void** vaddr, int flags,
  * Free a piece of memory and it's allociated dmamap, that was allocated
  * via bus_dmamem_alloc.
  */
+void bus_dmamem_free_size(bus_dma_tag_t dmat, void *vaddr, bus_dmamap_t map,
+			  bus_size_t size);
+
 void bus_dmamem_free(bus_dma_tag_t dmat, void *vaddr, bus_dmamap_t map);
 
 /*

sys/sparc64/include/bus.h

@@ -971,8 +971,12 @@ struct bus_dma_tag {
 	/*
 	 * DMA memory utility functions.
 	 */
+	int	(*dt_dmamem_alloc_size)(bus_dma_tag_t, bus_dma_tag_t, void **,
+	    int, bus_dmamap_t *, bus_size_t size);
 	int	(*dt_dmamem_alloc)(bus_dma_tag_t, bus_dma_tag_t, void **, int,
 	    bus_dmamap_t *);
+	void	(*dt_dmamem_free_size)(bus_dma_tag_t, bus_dma_tag_t, void *,
+	    bus_dmamap_t, bus_size_t size);
 	void	(*dt_dmamem_free)(bus_dma_tag_t, bus_dma_tag_t, void *,
 	    bus_dmamap_t);
 };
@@ -1083,6 +1087,19 @@ sparc64_dmamap_sync(bus_dma_tag_t pt, bus_dma_tag_t dt, bus_dmamap_t m,
 #define	bus_dmamap_sync(t, m, op)					\
 	sparc64_dmamap_sync((t), (t), (m), (op))
 
+static __inline int
+sparc64_dmamem_alloc_size(bus_dma_tag_t pt, bus_dma_tag_t dt, void **v, int f,
+    bus_dmamap_t *m, bus_size_t s)
+{
+	bus_dma_tag_t lt;
+
+	for (lt = pt; lt->dmamem_alloc == NULL; lt = lt->parent)
+		;
+	return ((*lt->dmamem_alloc_size)(lt, dt, v, f, m, s));
+}
+#define	bus_dmamem_alloc_size(t, v, f, m, s)				\
+	sparc64_dmamem_alloc_size((t), (t), (v), (f), (m), (s))
+
 static __inline int
 sparc64_dmamem_alloc(bus_dma_tag_t pt, bus_dma_tag_t dt, void **v, int f,
     bus_dmamap_t *m)
@@ -1096,6 +1113,19 @@ sparc64_dmamem_alloc(bus_dma_tag_t pt, bus_dma_tag_t dt, void **v, int f,
 #define	bus_dmamem_alloc(t, v, f, m)					\
 	sparc64_dmamem_alloc((t), (t), (v), (f), (m))
 
+static __inline void
+sparc64_dmamem_free_size(bus_dma_tag_t pt, bus_dma_tag_t dt, void *v,
+    bus_dmamap_t m, bus_size_t s)
+{
+	bus_dma_tag_t lt;
+
+	for (lt = pt; lt->dmamem_free == NULL; lt = lt->parent)
+		;
+	(*lt->dmamem_free_size)(lt, dt, v, m, s);
+}
+#define	bus_dmamem_free_size(t, v, m, s)				\
+	sparc64_dmamem_free_size((t), (t), (v), (m), (s))
+
 static __inline void
 sparc64_dmamem_free(bus_dma_tag_t pt, bus_dma_tag_t dt, void *v,
     bus_dmamap_t m)

sys/sparc64/include/iommuvar.h

@@ -95,8 +95,12 @@ void iommu_dvmamap_unload(bus_dma_tag_t, bus_dma_tag_t, struct iommu_state *,
     bus_dmamap_t);
 void iommu_dvmamap_sync(bus_dma_tag_t, bus_dma_tag_t, struct iommu_state *,
     bus_dmamap_t, bus_dmasync_op_t);
+int iommu_dvmamem_alloc_size(bus_dma_tag_t, bus_dma_tag_t, struct iommu_state *,
+    void **, int, bus_dmamap_t *, bus_size_t size);
 int iommu_dvmamem_alloc(bus_dma_tag_t, bus_dma_tag_t, struct iommu_state *,
     void **, int, bus_dmamap_t *);
+void iommu_dvmamem_free_size(bus_dma_tag_t, bus_dma_tag_t, struct iommu_state *,
+    void *, bus_dmamap_t, bus_size_t size);
 void iommu_dvmamem_free(bus_dma_tag_t, bus_dma_tag_t, struct iommu_state *,
     void *, bus_dmamap_t);
 

sys/sparc64/pci/psycho.c

@@ -113,8 +113,12 @@ static int psycho_dmamap_load_uio(bus_dma_tag_t, bus_dma_tag_t, bus_dmamap_t,
 static void psycho_dmamap_unload(bus_dma_tag_t, bus_dma_tag_t, bus_dmamap_t);
 static void psycho_dmamap_sync(bus_dma_tag_t, bus_dma_tag_t, bus_dmamap_t,
     bus_dmasync_op_t);
+static int psycho_dmamem_alloc_size(bus_dma_tag_t, bus_dma_tag_t, void **, int,
+    bus_dmamap_t *, bus_size_t size);
 static int psycho_dmamem_alloc(bus_dma_tag_t, bus_dma_tag_t, void **, int,
     bus_dmamap_t *);
+static void psycho_dmamem_free_size(bus_dma_tag_t, bus_dma_tag_t, void *,
+    bus_dmamap_t, bus_size_t size);
 static void psycho_dmamem_free(bus_dma_tag_t, bus_dma_tag_t, void *,
     bus_dmamap_t);
 
@@ -497,7 +501,9 @@ psycho_attach(device_t dev)
 	sc->sc_dmat->dt_dmamap_load_uio = psycho_dmamap_load_uio;
 	sc->sc_dmat->dt_dmamap_unload = psycho_dmamap_unload;
 	sc->sc_dmat->dt_dmamap_sync = psycho_dmamap_sync;
+	sc->sc_dmat->dt_dmamem_alloc_size = psycho_dmamem_alloc_size;
 	sc->sc_dmat->dt_dmamem_alloc = psycho_dmamem_alloc;
+	sc->sc_dmat->dt_dmamem_free_size = psycho_dmamem_free_size;
 	sc->sc_dmat->dt_dmamem_free = psycho_dmamem_free;
 	/* XXX: register as root dma tag (kluge). */
 	sparc64_root_dma_tag = sc->sc_dmat;
@@ -1313,6 +1319,17 @@ psycho_alloc_bus_tag(struct psycho_softc *sc, int type)
 /*
  * hooks into the iommu dvma calls.
  */
+static int
+psycho_dmamem_alloc_size(bus_dma_tag_t pdmat, bus_dma_tag_t ddmat, void **vaddr,
+    int flags, bus_dmamap_t *mapp, bus_size_t size)
+{
+	struct psycho_softc *sc;
+
+	sc = (struct psycho_softc *)pdmat->cookie;
+	return (iommu_dvmamem_alloc_size(pdmat, ddmat, sc->sc_is, vaddr, flags,
+	    mapp, size));
+}
+
 static int
 psycho_dmamem_alloc(bus_dma_tag_t pdmat, bus_dma_tag_t ddmat, void **vaddr,
     int flags, bus_dmamap_t *mapp)
@@ -1324,6 +1341,16 @@ psycho_dmamem_alloc(bus_dma_tag_t pdmat, bus_dma_tag_t ddmat, void **vaddr,
 	    mapp));
 }
 
+static void
+psycho_dmamem_free_size(bus_dma_tag_t pdmat, bus_dma_tag_t ddmat, void *vaddr,
+    bus_dmamap_t map, bus_size_t size)
+{
+	struct psycho_softc *sc;
+
+	sc = (struct psycho_softc *)pdmat->cookie;
+	iommu_dvmamem_free_size(pdmat, ddmat, sc->sc_is, vaddr, map, size);
+}
+
 static void
 psycho_dmamem_free(bus_dma_tag_t pdmat, bus_dma_tag_t ddmat, void *vaddr,
     bus_dmamap_t map)

sys/sparc64/sbus/sbus.c

@@ -244,8 +244,12 @@ static int sbus_dmamap_load_uio(bus_dma_tag_t, bus_dma_tag_t, bus_dmamap_t,
 static void sbus_dmamap_unload(bus_dma_tag_t, bus_dma_tag_t, bus_dmamap_t);
 static void sbus_dmamap_sync(bus_dma_tag_t, bus_dma_tag_t, bus_dmamap_t,
     bus_dmasync_op_t);
+static int sbus_dmamem_alloc_size(bus_dma_tag_t, bus_dma_tag_t, void **, int,
+    bus_dmamap_t *, bus_size_t size);
 static int sbus_dmamem_alloc(bus_dma_tag_t, bus_dma_tag_t, void **, int,
     bus_dmamap_t *);
+static void sbus_dmamem_free_size(bus_dma_tag_t, bus_dma_tag_t, void *,
+    bus_dmamap_t, bus_size_t);
 static void sbus_dmamem_free(bus_dma_tag_t, bus_dma_tag_t, void *,
     bus_dmamap_t);
 
@@ -349,7 +353,9 @@ sbus_probe(device_t dev)
 	sc->sc_cdmatag->dt_dmamap_load_uio = sbus_dmamap_load_uio;
 	sc->sc_cdmatag->dt_dmamap_unload = sbus_dmamap_unload;
 	sc->sc_cdmatag->dt_dmamap_sync = sbus_dmamap_sync;
+	sc->sc_cdmatag->dt_dmamem_alloc_size = sbus_dmamem_alloc_size;
 	sc->sc_cdmatag->dt_dmamem_alloc = sbus_dmamem_alloc;
+	sc->sc_cdmatag->dt_dmamem_free_size = sbus_dmamem_free_size;
 	sc->sc_cdmatag->dt_dmamem_free = sbus_dmamem_free;
 	/* XXX: register as root dma tag (kluge). */
 	sparc64_root_dma_tag = sc->sc_cdmatag;
@@ -987,6 +993,16 @@ sbus_dmamap_sync(bus_dma_tag_t pdmat, bus_dma_tag_t ddmat, bus_dmamap_t map,
 	iommu_dvmamap_sync(pdmat, ddmat, &sc->sc_is, map, op);
 }
 
+static int
+sbus_dmamem_alloc_size(bus_dma_tag_t pdmat, bus_dma_tag_t ddmat, void **vaddr,
+    int flags, bus_dmamap_t *mapp, bus_size_t size)
+{
+	struct sbus_softc *sc = (struct sbus_softc *)pdmat->cookie;
+
+	return (iommu_dvmamem_alloc_size(pdmat, ddmat, &sc->sc_is, vaddr, flags,
+		    mapp, size));
+}
+
 static int
 sbus_dmamem_alloc(bus_dma_tag_t pdmat, bus_dma_tag_t ddmat, void **vaddr,
     int flags, bus_dmamap_t *mapp)
@@ -997,6 +1013,15 @@ sbus_dmamem_alloc(bus_dma_tag_t pdmat, bus_dma_tag_t ddmat, void **vaddr,
 		    mapp));
 }
 
+static void
+sbus_dmamem_free_size(bus_dma_tag_t pdmat, bus_dma_tag_t ddmat, void *vaddr,
+    bus_dmamap_t map, bus_size_t size)
+{
+	struct sbus_softc *sc = (struct sbus_softc *)pdmat->cookie;
+
+	iommu_dvmamem_free_size(pdmat, ddmat, &sc->sc_is, vaddr, map, size);
+}
+
 static void
 sbus_dmamem_free(bus_dma_tag_t pdmat, bus_dma_tag_t ddmat, void *vaddr,
     bus_dmamap_t map)

sys/sparc64/sparc64/bus_machdep.c

@@ -168,8 +168,12 @@ static int nexus_dmamap_load_uio(bus_dma_tag_t, bus_dma_tag_t, bus_dmamap_t,
 static void nexus_dmamap_unload(bus_dma_tag_t, bus_dma_tag_t, bus_dmamap_t);
 static void nexus_dmamap_sync(bus_dma_tag_t, bus_dma_tag_t, bus_dmamap_t,
     bus_dmasync_op_t);
+static int nexus_dmamem_alloc_size(bus_dma_tag_t, bus_dma_tag_t, void **, int,
+    bus_dmamap_t *, u_long size);
 static int nexus_dmamem_alloc(bus_dma_tag_t, bus_dma_tag_t, void **, int,
     bus_dmamap_t *);
+static void nexus_dmamem_free_size(bus_dma_tag_t, bus_dma_tag_t, void *,
+    bus_dmamap_t, u_long size);
 static void nexus_dmamem_free(bus_dma_tag_t, bus_dma_tag_t, void *,
     bus_dmamap_t);
 
@@ -222,7 +226,9 @@ bus_dma_tag_create(bus_dma_tag_t parent, bus_size_t alignment,
 	newtag->dt_dmamap_load_uio = NULL;
 	newtag->dt_dmamap_unload = NULL;
 	newtag->dt_dmamap_sync = NULL;
+	newtag->dt_dmamem_alloc_size = NULL;
 	newtag->dt_dmamem_alloc = NULL;
+	newtag->dt_dmamem_free_size = NULL;
 	newtag->dt_dmamem_free = NULL;
 
 	/* Take into account any restrictions imposed by our parent tag */
@@ -604,12 +610,15 @@ sparc64_dmamem_free_map(bus_dma_tag_t dmat, bus_dmamap_t map)
  * by bus-specific DMA memory allocation functions.
  */
 static int
-nexus_dmamem_alloc(bus_dma_tag_t pdmat, bus_dma_tag_t ddmat, void **vaddr,
+nexus_dmamem_alloc_size(bus_dma_tag_t pdmat, bus_dma_tag_t ddmat, void **vaddr,
-    int flags, bus_dmamap_t *mapp)
+    int flags, bus_dmamap_t *mapp, bus_size_t size)
 {
 
-	if ((ddmat->dt_maxsize <= PAGE_SIZE)) {
+	if (size > ddmat->dt_maxsize)
-		*vaddr = malloc(ddmat->dt_maxsize, M_DEVBUF,
+		return (ENOMEM);
+
+	if ((size <= PAGE_SIZE)) {
+		*vaddr = malloc(size, M_DEVBUF,
 		    (flags & BUS_DMA_NOWAIT) ? M_NOWAIT : 0);
 	} else {
 		/*
@@ -617,7 +626,7 @@ nexus_dmamem_alloc(bus_dma_tag_t pdmat, bus_dma_tag_t ddmat, void **vaddr,
 		 * and handles multi-seg allocations.  Nobody is doing multi-seg
 		 * allocations yet though.
 		 */
-		*vaddr = contigmalloc(ddmat->dt_maxsize, M_DEVBUF,
+		*vaddr = contigmalloc(size, M_DEVBUF,
 		    (flags & BUS_DMA_NOWAIT) ? M_NOWAIT : 0,
 		    0ul, ddmat->dt_lowaddr,
 		    ddmat->dt_alignment ? ddmat->dt_alignment : 1UL,
@@ -630,20 +639,35 @@ nexus_dmamem_alloc(bus_dma_tag_t pdmat, bus_dma_tag_t ddmat, void **vaddr,
 	return (0);
 }
 
+static int
+nexus_dmamem_alloc(bus_dma_tag_t pdmat, bus_dma_tag_t ddmat, void **vaddr,
+    int flags, bus_dmamap_t *mapp)
+{
+	return (sparc64_dmamem_alloc_size(pdmat, ddmat, vaddr, flags, mapp,
+		ddmat->maxsize));
+}
+
 /*
  * Common function for freeing DMA-safe memory.  May be called by
  * bus-specific DMA memory free functions.
  */
 static void
-nexus_dmamem_free(bus_dma_tag_t pdmat, bus_dma_tag_t ddmat, void *vaddr,
+nexus_dmamem_free_size(bus_dma_tag_t pdmat, bus_dma_tag_t ddmat, void *vaddr,
-    bus_dmamap_t map)
+    bus_dmamap_t map, bus_size_t size)
 {
 
 	sparc64_dmamem_free_map(ddmat, map);
-	if ((ddmat->dt_maxsize <= PAGE_SIZE))
+	if ((size <= PAGE_SIZE))
 		free(vaddr, M_DEVBUF);
 	else
-		contigfree(vaddr, ddmat->dt_maxsize, M_DEVBUF);
+		contigfree(vaddr, size, M_DEVBUF);
+}
+
+static void
+nexus_dmamem_free(bus_dma_tag_t pdmat, bus_dma_tag_t ddmat, void *vaddr,
+    bus_dmamap_t map)
+{
+	sparc64_dmamem_free_size(pdmat, ddmat, vaddr, map, ddmat->dt_maxsize);
 }
 
 struct bus_dma_tag nexus_dmatag = {
@@ -669,7 +693,9 @@ struct bus_dma_tag nexus_dmatag = {
 	nexus_dmamap_unload,
 	nexus_dmamap_sync,
 
+	nexus_dmamem_alloc_size,
 	nexus_dmamem_alloc,
+	nexus_dmamem_free_size,
 	nexus_dmamem_free,
 };
 

sys/sparc64/sparc64/iommu.c

@@ -668,18 +668,22 @@ iommu_dvma_vallocseg(bus_dma_tag_t dt, struct iommu_state *is, bus_dmamap_t map,
 }
 
 int
-iommu_dvmamem_alloc(bus_dma_tag_t pt, bus_dma_tag_t dt, struct iommu_state *is,
+iommu_dvmamem_alloc_size(bus_dma_tag_t pt, bus_dma_tag_t dt,
-    void **vaddr, int flags, bus_dmamap_t *mapp)
+    struct iommu_state *is, void **vaddr, int flags, bus_dmamap_t *mapp,
+    bus_size_t size)
 {
 	int error;
 
+	if (size > dt->maxsize)
+		return (ENOMEM);
+
 	/*
 	 * XXX: This will break for 32 bit transfers on machines with more than
 	 * 16G (1 << 34 bytes) of memory.
 	 */
 	if ((error = sparc64_dmamem_alloc_map(dt, mapp)) != 0)
 		return (error);
-	if ((*vaddr = malloc(dt->dt_maxsize, M_IOMMU,
+	if ((*vaddr = malloc(size, M_IOMMU,
 	    (flags & BUS_DMA_NOWAIT) ? M_NOWAIT : 0)) == NULL) {
 		error = ENOMEM;
 		sparc64_dmamem_free_map(dt, *mapp);
@@ -690,18 +694,33 @@ iommu_dvmamem_alloc(bus_dma_tag_t pt, bus_dma_tag_t dt, struct iommu_state *is,
 	 * Try to preallocate DVMA space. If this fails, it is retried at load
 	 * time.
 	 */
-	iommu_dvma_valloc(dt, is, *mapp, IOMMU_SIZE_ROUNDUP(dt->dt_maxsize));
+	iommu_dvma_valloc(dt, is, *mapp, IOMMU_SIZE_ROUNDUP(size));
 	return (0);
 }
 
+int
+iommu_dvmamem_alloc(bus_dma_tag_t pt, bus_dma_tag_t dt, struct iommu_state *is,
+    void **vaddr, int flags, bus_dmamap_t *mapp)
+{
+	return (iommu_dvmamem_alloc_size(pt, dt, is, vaddr, flags, mapp,
+	    dt->maxsize));
+}
+
+void
+iommu_dvmamem_free_size(bus_dma_tag_t pt, bus_dma_tag_t dt,
+    struct iommu_state *is, void *vaddr, bus_dmamap_t map, bus_size_t size)
+{
+
+	iommu_dvma_vfree(is, map);
+	sparc64_dmamem_free_map(dt, map);
+	free(vaddr, M_IOMMU);
+}
+
 void
 iommu_dvmamem_free(bus_dma_tag_t pt, bus_dma_tag_t dt, struct iommu_state *is,
     void *vaddr, bus_dmamap_t map)
 {
-
+	iommu_dvmamem_free_size(pt, dt, is, vaddr, map, dt->maxsize);
-	iommu_dvma_vfree(is, map);
-	sparc64_dmamem_free_map(dt, map);
-	free(vaddr, M_IOMMU);
 }
 
 int

sys/sys/bus_dma.h

@@ -180,6 +180,9 @@ int bus_dmamap_destroy(bus_dma_tag_t dmat, bus_dmamap_t map);
  * bus device space based on the constraints lited in the dma tag.
  * A dmamap to for use with dmamap_load is also allocated.
  */
+int bus_dmamem_alloc_size(bus_dma_tag_t dmat, void** vaddr, int flags,
+			  bus_dmamap_t *mapp, bus_size_t size);
+
 int bus_dmamem_alloc(bus_dma_tag_t dmat, void** vaddr, int flags,
 		     bus_dmamap_t *mapp);
 
@@ -187,6 +190,9 @@ int bus_dmamem_alloc(bus_dma_tag_t dmat, void** vaddr, int flags,
  * Free a piece of memory and it's allociated dmamap, that was allocated
  * via bus_dmamem_alloc.
  */
+void bus_dmamem_free_size(bus_dma_tag_t dmat, void *vaddr, bus_dmamap_t map,
+			  bus_size_t size);
+
 void bus_dmamem_free(bus_dma_tag_t dmat, void *vaddr, bus_dmamap_t map);
 
 /*