[SPARC64]: Handle SBUS dma allocations larger than 1MB.

Signed-off-by: David Dillow <dave@thedillows.org>
Signed-off-by: David S. Miller <davem@redhat.com>

arch/sparc64/kernel/sbus.c

@@ -28,10 +28,10 @@
  *
  * On SYSIO, using an 8K page size we have 1GB of SBUS
  * DMA space mapped.  We divide this space into equally
- * sized clusters.  Currently we allow clusters up to a
- * size of 1MB.  If anything begins to generate DMA
- * mapping requests larger than this we will need to
- * increase things a bit.
+ * sized clusters. We allocate a DMA mapping from the
+ * cluster that matches the order of the allocation, or
+ * if the order is greater than the number of clusters,
+ * we try to allocate from the last cluster.
  */
 
 #define NCLUSTERS	8UL
@@ -134,12 +134,17 @@ static void strbuf_flush(struct sbus_iommu *iommu, u32 base, unsigned long npage
 
 static iopte_t *alloc_streaming_cluster(struct sbus_iommu *iommu, unsigned long npages)
 {
-	iopte_t *iopte, *limit, *first;
-	unsigned long cnum, ent, flush_point;
+	iopte_t *iopte, *limit, *first, *cluster;
+	unsigned long cnum, ent, nent, flush_point, found;
 
 	cnum = 0;
+	nent = 1;
 	while ((1UL << cnum) < npages)
 		cnum++;
+	if(cnum >= NCLUSTERS) {
+		nent = 1UL << (cnum - NCLUSTERS);
+		cnum = NCLUSTERS - 1;
+	}
 	iopte  = iommu->page_table + (cnum * CLUSTER_NPAGES);
 
 	if (cnum == 0)
@@ -152,22 +157,31 @@ static iopte_t *alloc_streaming_cluster(struct sbus_iommu *iommu, unsigned long
 	flush_point = iommu->alloc_info[cnum].flush;
 
 	first = iopte;
+	cluster = NULL;
+	found = 0;
 	for (;;) {
 		if (iopte_val(*iopte) == 0UL) {
-			if ((iopte + (1 << cnum)) >= limit)
-				ent = 0;
-			else
-				ent = ent + 1;
-			iommu->alloc_info[cnum].next = ent;
-			if (ent == flush_point)
-				__iommu_flushall(iommu);
-			break;
+			found++;
+			if (!cluster)
+				cluster = iopte;
+		} else {
+			/* Used cluster in the way */
+			cluster = NULL;
+			found = 0;
 		}
+
+		if (found == nent)
+			break;
+
 		iopte += (1 << cnum);
 		ent++;
 		if (iopte >= limit) {
 			iopte = (iommu->page_table + (cnum * CLUSTER_NPAGES));
 			ent = 0;
+
+			/* Multiple cluster allocations must not wrap */
+			cluster = NULL;
+			found = 0;
 		}
 		if (ent == flush_point)
 			__iommu_flushall(iommu);
@@ -175,8 +189,19 @@ static iopte_t *alloc_streaming_cluster(struct sbus_iommu *iommu, unsigned long
 			goto bad;
 	}
 
+	/* ent/iopte points to the last cluster entry we're going to use,
+	 * so save our place for the next allocation.
+	 */
+	if ((iopte + (1 << cnum)) >= limit)
+		ent = 0;
+	else
+		ent = ent + 1;
+	iommu->alloc_info[cnum].next = ent;
+	if (ent == flush_point)
+		__iommu_flushall(iommu);
+
 	/* I've got your streaming cluster right here buddy boy... */
-	return iopte;
+	return cluster;
 
 bad:
 	printk(KERN_EMERG "sbus: alloc_streaming_cluster of npages(%ld) failed!\n",
@@ -186,15 +211,23 @@ static iopte_t *alloc_streaming_cluster(struct sbus_iommu *iommu, unsigned long
 
 static void free_streaming_cluster(struct sbus_iommu *iommu, u32 base, unsigned long npages)
 {
-	unsigned long cnum, ent;
+	unsigned long cnum, ent, nent;
 	iopte_t *iopte;
 
 	cnum = 0;
+	nent = 1;
 	while ((1UL << cnum) < npages)
 		cnum++;
+	if(cnum >= NCLUSTERS) {
+		nent = 1UL << (cnum - NCLUSTERS);
+		cnum = NCLUSTERS - 1;
+	}
 	ent = (base & CLUSTER_MASK) >> (IO_PAGE_SHIFT + cnum);
 	iopte = iommu->page_table + ((base - MAP_BASE) >> IO_PAGE_SHIFT);
+	do {
 		iopte_val(*iopte) = 0UL;
+		iopte += 1 << cnum;
+	} while(--nent);
 
 	/* If the global flush might not have caught this entry,
 	 * adjust the flush point such that we will flush before