[SPARC64]: Fix SBUS IOMMU allocation code.

There are several IOMMU allocator bugs. Instead of trying to fix this
overly complicated code, just mirror the PCI IOMMU arena allocator
which is very stable and well stress tested.

I tried to make the code as identical as possible so we can switch
sun4u PCI and SBUS over to a common piece of IOMMU code. All that
will be need are two callbacks, one to do a full IOMMU flush and one
to do a streaming buffer flush.

This patch gets rid of a lot of hangs and mysterious crashes on SBUS
sparc64 systems, at least for me.

Signed-off-by: David S. Miller <[e-mail]>

arch/sparc64/kernel/sbus.c

···
 
 #include "iommu_common.h"
 
-/* These should be allocated on an SMP_CACHE_BYTES
- * aligned boundary for optimal performance.
- *
- * On SYSIO, using an 8K page size we have 1GB of SBUS
- * DMA space mapped.  We divide this space into equally
- * 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
-#define ONE_GIG		(1UL * 1024UL * 1024UL * 1024UL)
-#define CLUSTER_SIZE	(ONE_GIG / NCLUSTERS)
-#define CLUSTER_MASK	(CLUSTER_SIZE - 1)
-#define CLUSTER_NPAGES	(CLUSTER_SIZE >> IO_PAGE_SHIFT)
 #define MAP_BASE	((u32)0xc0000000)
 
+struct sbus_iommu_arena {
+	unsigned long	*map;
+	unsigned int	hint;
+	unsigned int	limit;
+};
+
 struct sbus_iommu {
-/*0x00*/spinlock_t		lock;
+	spinlock_t		lock;
 
-/*0x08*/iopte_t			*page_table;
-/*0x10*/unsigned long		strbuf_regs;
-/*0x18*/unsigned long		iommu_regs;
-/*0x20*/unsigned long		sbus_control_reg;
+	struct sbus_iommu_arena	arena;
 
-/*0x28*/volatile unsigned long	strbuf_flushflag;
+	iopte_t			*page_table;
+	unsigned long		strbuf_regs;
+	unsigned long		iommu_regs;
+	unsigned long		sbus_control_reg;
 
-	/* If NCLUSTERS is ever decresed to 4 or lower,
-	 * you must increase the size of the type of
-	 * these counters.  You have been duly warned. -DaveM
-	 */
-/*0x30*/struct {
-		u16	next;
-		u16	flush;
-	} alloc_info[NCLUSTERS];
-
-	/* The lowest used consistent mapping entry.  Since
-	 * we allocate consistent maps out of cluster 0 this
-	 * is relative to the beginning of closter 0.
-	 */
-/*0x50*/u32		lowest_consistent_map;
+	volatile unsigned long	strbuf_flushflag;
 };
 
 /* Offsets from iommu_regs */
···
 		upa_writeq(0, tag);
 		tag += 8UL;
 	}
-	upa_readq(iommu->sbus_control_reg);
-
-	for (entry = 0; entry < NCLUSTERS; entry++) {
-		iommu->alloc_info[entry].flush =
-			iommu->alloc_info[entry].next;
-	}
-}
-
-static void iommu_flush(struct sbus_iommu *iommu, u32 base, unsigned long npages)
-{
-	while (npages--)
-		upa_writeq(base + (npages << IO_PAGE_SHIFT),
-			   iommu->iommu_regs + IOMMU_FLUSH);
 	upa_readq(iommu->sbus_control_reg);
 }
 
···
 		       base, npages);
 }
 
-static iopte_t *alloc_streaming_cluster(struct sbus_iommu *iommu, unsigned long npages)
+/* Based largely upon the ppc64 iommu allocator.  */
+static long sbus_arena_alloc(struct sbus_iommu *iommu, unsigned long npages)
 {
-	iopte_t *iopte, *limit, *first, *cluster;
-	unsigned long cnum, ent, nent, flush_point, found;
+	struct sbus_iommu_arena *arena = &iommu->arena;
+	unsigned long n, i, start, end, limit;
+	int pass;
 
-	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);
+	limit = arena->limit;
+	start = arena->hint;
+	pass = 0;
 
-	if (cnum == 0)
-		limit = (iommu->page_table +
-			 iommu->lowest_consistent_map);
-	else
-		limit = (iopte + CLUSTER_NPAGES);
-
-	iopte += ((ent = iommu->alloc_info[cnum].next) << cnum);
-	flush_point = iommu->alloc_info[cnum].flush;
-
-	first = iopte;
-	cluster = NULL;
-	found = 0;
-	for (;;) {
-		if (iopte_val(*iopte) == 0UL) {
-			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)
+again:
+	n = find_next_zero_bit(arena->map, limit, start);
+	end = n + npages;
+	if (unlikely(end >= limit)) {
+		if (likely(pass < 1)) {
+			limit = start;
+			start = 0;
 			__iommu_flushall(iommu);
-		if (iopte == first)
-			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 cluster;
-
-bad:
-	printk(KERN_EMERG "sbus: alloc_streaming_cluster of npages(%ld) failed!\n",
-	       npages);
-	return NULL;
-}
-
-static void free_streaming_cluster(struct sbus_iommu *iommu, u32 base, unsigned long npages)
-{
-	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
-	 * ever trying to reuse it.
-	 */
-#define between(X,Y,Z)	(((Z) - (Y)) >= ((X) - (Y)))
-	if (between(ent, iommu->alloc_info[cnum].next, iommu->alloc_info[cnum].flush))
-		iommu->alloc_info[cnum].flush = ent;
-#undef between
-}
-
-/* We allocate consistent mappings from the end of cluster zero. */
-static iopte_t *alloc_consistent_cluster(struct sbus_iommu *iommu, unsigned long npages)
-{
-	iopte_t *iopte;
-
-	iopte = iommu->page_table + (1 * CLUSTER_NPAGES);
-	while (iopte > iommu->page_table) {
-		iopte--;
-		if (!(iopte_val(*iopte) & IOPTE_VALID)) {
-			unsigned long tmp = npages;
-
-			while (--tmp) {
-				iopte--;
-				if (iopte_val(*iopte) & IOPTE_VALID)
-					break;
-			}
-			if (tmp == 0) {
-				u32 entry = (iopte - iommu->page_table);
-
-				if (entry < iommu->lowest_consistent_map)
-					iommu->lowest_consistent_map = entry;
-				return iopte;
-			}
+			pass++;
+			goto again;
+		} else {
+			/* Scanned the whole thing, give up. */
+			return -1;
 		}
 	}
-	return NULL;
-}
 
-static void free_consistent_cluster(struct sbus_iommu *iommu, u32 base, unsigned long npages)
-{
-	iopte_t *iopte = iommu->page_table + ((base - MAP_BASE) >> IO_PAGE_SHIFT);
-
-	if ((iopte - iommu->page_table) == iommu->lowest_consistent_map) {
-		iopte_t *walk = iopte + npages;
-		iopte_t *limit;
-
-		limit = iommu->page_table + CLUSTER_NPAGES;
-		while (walk < limit) {
-			if (iopte_val(*walk) != 0UL)
-				break;
-			walk++;
+	for (i = n; i < end; i++) {
+		if (test_bit(i, arena->map)) {
+			start = i + 1;
+			goto again;
 		}
-		iommu->lowest_consistent_map =
-			(walk - iommu->page_table);
 	}
 
-	while (npages--)
-		*iopte++ = __iopte(0UL);
+	for (i = n; i < end; i++)
+		__set_bit(i, arena->map);
+
+	arena->hint = end;
+
+	return n;
+}
+
+static void sbus_arena_free(struct sbus_iommu_arena *arena, unsigned long base, unsigned long npages)
+{
+	unsigned long i;
+
+	for (i = base; i < (base + npages); i++)
+		__clear_bit(i, arena->map);
+}
+
+static void sbus_iommu_table_init(struct sbus_iommu *iommu, unsigned int tsbsize)
+{
+	unsigned long tsbbase, order, sz, num_tsb_entries;
+
+	num_tsb_entries = tsbsize / sizeof(iopte_t);
+
+	/* Setup initial software IOMMU state. */
+	spin_lock_init(&iommu->lock);
+
+	/* Allocate and initialize the free area map.  */
+	sz = num_tsb_entries / 8;
+	sz = (sz + 7UL) & ~7UL;
+	iommu->arena.map = kzalloc(sz, GFP_KERNEL);
+	if (!iommu->arena.map) {
+		prom_printf("PCI_IOMMU: Error, kmalloc(arena.map) failed.\n");
+		prom_halt();
+	}
+	iommu->arena.limit = num_tsb_entries;
+
+	/* Now allocate and setup the IOMMU page table itself.  */
+	order = get_order(tsbsize);
+	tsbbase = __get_free_pages(GFP_KERNEL, order);
+	if (!tsbbase) {
+		prom_printf("IOMMU: Error, gfp(tsb) failed.\n");
+		prom_halt();
+	}
+	iommu->page_table = (iopte_t *)tsbbase;
+	memset(iommu->page_table, 0, tsbsize);
+}
+
+static inline iopte_t *alloc_npages(struct sbus_iommu *iommu, unsigned long npages)
+{
+	long entry;
+
+	entry = sbus_arena_alloc(iommu, npages);
+	if (unlikely(entry < 0))
+		return NULL;
+
+	return iommu->page_table + entry;
+}
+
+static inline void free_npages(struct sbus_iommu *iommu, dma_addr_t base, unsigned long npages)
+{
+	sbus_arena_free(&iommu->arena, base >> IO_PAGE_SHIFT, npages);
 }
 
 void *sbus_alloc_consistent(struct sbus_dev *sdev, size_t size, dma_addr_t *dvma_addr)
 {
-	unsigned long order, first_page, flags;
 	struct sbus_iommu *iommu;
 	iopte_t *iopte;
+	unsigned long flags, order, first_page;
 	void *ret;
 	int npages;
-
-	if (size <= 0 || sdev == NULL || dvma_addr == NULL)
-		return NULL;
 
 	size = IO_PAGE_ALIGN(size);
 	order = get_order(size);
 	if (order >= 10)
 		return NULL;
+
 	first_page = __get_free_pages(GFP_KERNEL|__GFP_COMP, order);
 	if (first_page == 0UL)
 		return NULL;
···
 	iommu = sdev->bus->iommu;
 
 	spin_lock_irqsave(&iommu->lock, flags);
-	iopte = alloc_consistent_cluster(iommu, size >> IO_PAGE_SHIFT);
-	if (iopte == NULL) {
-		spin_unlock_irqrestore(&iommu->lock, flags);
+	iopte = alloc_npages(iommu, size >> IO_PAGE_SHIFT);
+	spin_unlock_irqrestore(&iommu->lock, flags);
+
+	if (unlikely(iopte == NULL)) {
 		free_pages(first_page, order);
 		return NULL;
 	}
 
-	/* Ok, we're committed at this point. */
-	*dvma_addr = MAP_BASE +	((iopte - iommu->page_table) << IO_PAGE_SHIFT);
+	*dvma_addr = (MAP_BASE +
+		      ((iopte - iommu->page_table) << IO_PAGE_SHIFT));
 	ret = (void *) first_page;
 	npages = size >> IO_PAGE_SHIFT;
+	first_page = __pa(first_page);
 	while (npages--) {
-		*iopte++ = __iopte(IOPTE_VALID | IOPTE_CACHE | IOPTE_WRITE |
-				   (__pa(first_page) & IOPTE_PAGE));
+		iopte_val(*iopte) = (IOPTE_VALID | IOPTE_CACHE |
+				     IOPTE_WRITE |
+				     (first_page & IOPTE_PAGE));
+		iopte++;
 		first_page += IO_PAGE_SIZE;
 	}
-	iommu_flush(iommu, *dvma_addr, size >> IO_PAGE_SHIFT);
-	spin_unlock_irqrestore(&iommu->lock, flags);
 
 	return ret;
 }
 
 void sbus_free_consistent(struct sbus_dev *sdev, size_t size, void *cpu, dma_addr_t dvma)
 {
-	unsigned long order, npages;
 	struct sbus_iommu *iommu;
-
-	if (size <= 0 || sdev == NULL || cpu == NULL)
-		return;
+	iopte_t *iopte;
+	unsigned long flags, order, npages;
 
 	npages = IO_PAGE_ALIGN(size) >> IO_PAGE_SHIFT;
 	iommu = sdev->bus->iommu;
+	iopte = iommu->page_table +
+		((dvma - MAP_BASE) >> IO_PAGE_SHIFT);
 
-	spin_lock_irq(&iommu->lock);
-	free_consistent_cluster(iommu, dvma, npages);
-	iommu_flush(iommu, dvma, npages);
-	spin_unlock_irq(&iommu->lock);
+	spin_lock_irqsave(&iommu->lock, flags);
+
+	free_npages(iommu, dvma - MAP_BASE, npages);
+
+	spin_unlock_irqrestore(&iommu->lock, flags);
 
 	order = get_order(size);
 	if (order < 10)
 		free_pages((unsigned long)cpu, order);
 }
 
-dma_addr_t sbus_map_single(struct sbus_dev *sdev, void *ptr, size_t size, int dir)
+dma_addr_t sbus_map_single(struct sbus_dev *sdev, void *ptr, size_t sz, int direction)
 {
-	struct sbus_iommu *iommu = sdev->bus->iommu;
-	unsigned long npages, pbase, flags;
-	iopte_t *iopte;
-	u32 dma_base, offset;
-	unsigned long iopte_bits;
+	struct sbus_iommu *iommu;
+	iopte_t *base;
+	unsigned long flags, npages, oaddr;
+	unsigned long i, base_paddr;
+	u32 bus_addr, ret;
+	unsigned long iopte_protection;
 
-	if (dir == SBUS_DMA_NONE)
+	iommu = sdev->bus->iommu;
+
+	if (unlikely(direction == SBUS_DMA_NONE))
 		BUG();
 
-	pbase = (unsigned long) ptr;
-	offset = (u32) (pbase & ~IO_PAGE_MASK);
-	size = (IO_PAGE_ALIGN(pbase + size) - (pbase & IO_PAGE_MASK));
-	pbase = (unsigned long) __pa(pbase & IO_PAGE_MASK);
+	oaddr = (unsigned long)ptr;
+	npages = IO_PAGE_ALIGN(oaddr + sz) - (oaddr & IO_PAGE_MASK);
+	npages >>= IO_PAGE_SHIFT;
 
 	spin_lock_irqsave(&iommu->lock, flags);
-	npages = size >> IO_PAGE_SHIFT;
-	iopte = alloc_streaming_cluster(iommu, npages);
-	if (iopte == NULL)
-		goto bad;
-	dma_base = MAP_BASE + ((iopte - iommu->page_table) << IO_PAGE_SHIFT);
-	npages = size >> IO_PAGE_SHIFT;
-	iopte_bits = IOPTE_VALID | IOPTE_STBUF | IOPTE_CACHE;
-	if (dir != SBUS_DMA_TODEVICE)
-		iopte_bits |= IOPTE_WRITE;
-	while (npages--) {
-		*iopte++ = __iopte(iopte_bits | (pbase & IOPTE_PAGE));
-		pbase += IO_PAGE_SIZE;
-	}
-	npages = size >> IO_PAGE_SHIFT;
+	base = alloc_npages(iommu, npages);
 	spin_unlock_irqrestore(&iommu->lock, flags);
 
-	return (dma_base | offset);
+	if (unlikely(!base))
+		BUG();
 
-bad:
-	spin_unlock_irqrestore(&iommu->lock, flags);
-	BUG();
-	return 0;
+	bus_addr = (MAP_BASE +
+		    ((base - iommu->page_table) << IO_PAGE_SHIFT));
+	ret = bus_addr | (oaddr & ~IO_PAGE_MASK);
+	base_paddr = __pa(oaddr & IO_PAGE_MASK);
+
+	iopte_protection = IOPTE_VALID | IOPTE_STBUF | IOPTE_CACHE;
+	if (direction != SBUS_DMA_TODEVICE)
+		iopte_protection |= IOPTE_WRITE;
+
+	for (i = 0; i < npages; i++, base++, base_paddr += IO_PAGE_SIZE)
+		iopte_val(*base) = iopte_protection | base_paddr;
+
+	return ret;
 }
 
-void sbus_unmap_single(struct sbus_dev *sdev, dma_addr_t dma_addr, size_t size, int direction)
+void sbus_unmap_single(struct sbus_dev *sdev, dma_addr_t bus_addr, size_t sz, int direction)
 {
 	struct sbus_iommu *iommu = sdev->bus->iommu;
-	u32 dma_base = dma_addr & IO_PAGE_MASK;
-	unsigned long flags;
+	iopte_t *base;
+	unsigned long flags, npages, i;
 
-	size = (IO_PAGE_ALIGN(dma_addr + size) - dma_base);
+	if (unlikely(direction == SBUS_DMA_NONE))
+		BUG();
+
+	npages = IO_PAGE_ALIGN(bus_addr + sz) - (bus_addr & IO_PAGE_MASK);
+	npages >>= IO_PAGE_SHIFT;
+	base = iommu->page_table +
+		((bus_addr - MAP_BASE) >> IO_PAGE_SHIFT);
+
+	bus_addr &= IO_PAGE_MASK;
 
 	spin_lock_irqsave(&iommu->lock, flags);
-	free_streaming_cluster(iommu, dma_base, size >> IO_PAGE_SHIFT);
-	sbus_strbuf_flush(iommu, dma_base, size >> IO_PAGE_SHIFT, direction);
+	sbus_strbuf_flush(iommu, bus_addr, npages, direction);
+	for (i = 0; i < npages; i++)
+		iopte_val(base[i]) = 0UL;
+	free_npages(iommu, bus_addr - MAP_BASE, npages);
 	spin_unlock_irqrestore(&iommu->lock, flags);
 }
 
 #define SG_ENT_PHYS_ADDRESS(SG)	\
 	(__pa(page_address((SG)->page)) + (SG)->offset)
 
-static inline void fill_sg(iopte_t *iopte, struct scatterlist *sg, int nused, int nelems, unsigned long iopte_bits)
+static inline void fill_sg(iopte_t *iopte, struct scatterlist *sg,
+			   int nused, int nelems, unsigned long iopte_protection)
 {
 	struct scatterlist *dma_sg = sg;
 	struct scatterlist *sg_end = sg + nelems;
···
 			for (;;) {
 				unsigned long tmp;
 
-				tmp = (unsigned long) SG_ENT_PHYS_ADDRESS(sg);
+				tmp = SG_ENT_PHYS_ADDRESS(sg);
 				len = sg->length;
 				if (((tmp ^ pteval) >> IO_PAGE_SHIFT) != 0UL) {
 					pteval = tmp & IO_PAGE_MASK;
···
 				sg++;
 			}
 
-			pteval = ((pteval & IOPTE_PAGE) | iopte_bits);
+			pteval = iopte_protection | (pteval & IOPTE_PAGE);
 			while (len > 0) {
 				*iopte++ = __iopte(pteval);
 				pteval += IO_PAGE_SIZE;
···
 	}
 }
 
-int sbus_map_sg(struct sbus_dev *sdev, struct scatterlist *sg, int nents, int dir)
+int sbus_map_sg(struct sbus_dev *sdev, struct scatterlist *sglist, int nelems, int direction)
 {
-	struct sbus_iommu *iommu = sdev->bus->iommu;
-	unsigned long flags, npages;
-	iopte_t *iopte;
+	struct sbus_iommu *iommu;
+	unsigned long flags, npages, iopte_protection;
+	iopte_t *base;
 	u32 dma_base;
 	struct scatterlist *sgtmp;
 	int used;
-	unsigned long iopte_bits;
-
-	if (dir == SBUS_DMA_NONE)
-		BUG();
 
 	/* Fast path single entry scatterlists. */
-	if (nents == 1) {
-		sg->dma_address =
+	if (nelems == 1) {
+		sglist->dma_address =
 			sbus_map_single(sdev,
-					(page_address(sg->page) + sg->offset),
-					sg->length, dir);
-		sg->dma_length = sg->length;
+					(page_address(sglist->page) + sglist->offset),
+					sglist->length, direction);
+		sglist->dma_length = sglist->length;
 		return 1;
 	}
 
-	npages = prepare_sg(sg, nents);
+	iommu = sdev->bus->iommu;
+
+	if (unlikely(direction == SBUS_DMA_NONE))
+		BUG();
+
+	npages = prepare_sg(sglist, nelems);
 
 	spin_lock_irqsave(&iommu->lock, flags);
-	iopte = alloc_streaming_cluster(iommu, npages);
-	if (iopte == NULL)
-		goto bad;
-	dma_base = MAP_BASE + ((iopte - iommu->page_table) << IO_PAGE_SHIFT);
+	base = alloc_npages(iommu, npages);
+	spin_unlock_irqrestore(&iommu->lock, flags);
+
+	if (unlikely(base == NULL))
+		BUG();
+
+	dma_base = MAP_BASE +
+		((base - iommu->page_table) << IO_PAGE_SHIFT);
 
 	/* Normalize DVMA addresses. */
-	sgtmp = sg;
-	used = nents;
+	used = nelems;
 
+	sgtmp = sglist;
 	while (used && sgtmp->dma_length) {
 		sgtmp->dma_address += dma_base;
 		sgtmp++;
 		used--;
 	}
-	used = nents - used;
+	used = nelems - used;
 
-	iopte_bits = IOPTE_VALID | IOPTE_STBUF | IOPTE_CACHE;
-	if (dir != SBUS_DMA_TODEVICE)
-		iopte_bits |= IOPTE_WRITE;
+	iopte_protection = IOPTE_VALID | IOPTE_STBUF | IOPTE_CACHE;
+	if (direction != SBUS_DMA_TODEVICE)
+		iopte_protection |= IOPTE_WRITE;
 
-	fill_sg(iopte, sg, used, nents, iopte_bits);
+	fill_sg(base, sglist, used, nelems, iopte_protection);
+
 #ifdef VERIFY_SG
-	verify_sglist(sg, nents, iopte, npages);
+	verify_sglist(sglist, nelems, base, npages);
 #endif
-	spin_unlock_irqrestore(&iommu->lock, flags);
 
 	return used;
-
-bad:
-	spin_unlock_irqrestore(&iommu->lock, flags);
-	BUG();
-	return 0;
 }
 
-void sbus_unmap_sg(struct sbus_dev *sdev, struct scatterlist *sg, int nents, int direction)
+void sbus_unmap_sg(struct sbus_dev *sdev, struct scatterlist *sglist, int nelems, int direction)
 {
-	unsigned long size, flags;
 	struct sbus_iommu *iommu;
-	u32 dvma_base;
-	int i;
+	iopte_t *base;
+	unsigned long flags, i, npages;
+	u32 bus_addr;
 
-	/* Fast path single entry scatterlists. */
-	if (nents == 1) {
-		sbus_unmap_single(sdev, sg->dma_address, sg->dma_length, direction);
-		return;
-	}
-
-	dvma_base = sg[0].dma_address & IO_PAGE_MASK;
-	for (i = 0; i < nents; i++) {
-		if (sg[i].dma_length == 0)
-			break;
-	}
-	i--;
-	size = IO_PAGE_ALIGN(sg[i].dma_address + sg[i].dma_length) - dvma_base;
+	if (unlikely(direction == SBUS_DMA_NONE))
+		BUG();
 
 	iommu = sdev->bus->iommu;
+
+	bus_addr = sglist->dma_address & IO_PAGE_MASK;
+
+	for (i = 1; i < nelems; i++)
+		if (sglist[i].dma_length == 0)
+			break;
+	i--;
+	npages = (IO_PAGE_ALIGN(sglist[i].dma_address + sglist[i].dma_length) -
+		  bus_addr) >> IO_PAGE_SHIFT;
+
+	base = iommu->page_table +
+		((bus_addr - MAP_BASE) >> IO_PAGE_SHIFT);
+
 	spin_lock_irqsave(&iommu->lock, flags);
-	free_streaming_cluster(iommu, dvma_base, size >> IO_PAGE_SHIFT);
-	sbus_strbuf_flush(iommu, dvma_base, size >> IO_PAGE_SHIFT, direction);
+	sbus_strbuf_flush(iommu, bus_addr, npages, direction);
+	for (i = 0; i < npages; i++)
+		iopte_val(base[i]) = 0UL;
+	free_npages(iommu, bus_addr - MAP_BASE, npages);
 	spin_unlock_irqrestore(&iommu->lock, flags);
 }
 
-void sbus_dma_sync_single_for_cpu(struct sbus_dev *sdev, dma_addr_t base, size_t size, int direction)
+void sbus_dma_sync_single_for_cpu(struct sbus_dev *sdev, dma_addr_t bus_addr, size_t sz, int direction)
 {
-	struct sbus_iommu *iommu = sdev->bus->iommu;
-	unsigned long flags;
+	struct sbus_iommu *iommu;
+	unsigned long flags, npages;
 
-	size = (IO_PAGE_ALIGN(base + size) - (base & IO_PAGE_MASK));
+	iommu = sdev->bus->iommu;
+
+	npages = IO_PAGE_ALIGN(bus_addr + sz) - (bus_addr & IO_PAGE_MASK);
+	npages >>= IO_PAGE_SHIFT;
+	bus_addr &= IO_PAGE_MASK;
 
 	spin_lock_irqsave(&iommu->lock, flags);
-	sbus_strbuf_flush(iommu, base & IO_PAGE_MASK, size >> IO_PAGE_SHIFT, direction);
+	sbus_strbuf_flush(iommu, bus_addr, npages, direction);
 	spin_unlock_irqrestore(&iommu->lock, flags);
 }
 
···
 {
 }
 
-void sbus_dma_sync_sg_for_cpu(struct sbus_dev *sdev, struct scatterlist *sg, int nents, int direction)
+void sbus_dma_sync_sg_for_cpu(struct sbus_dev *sdev, struct scatterlist *sglist, int nelems, int direction)
 {
-	struct sbus_iommu *iommu = sdev->bus->iommu;
-	unsigned long flags, size;
-	u32 base;
-	int i;
+	struct sbus_iommu *iommu;
+	unsigned long flags, npages, i;
+	u32 bus_addr;
 
-	base = sg[0].dma_address & IO_PAGE_MASK;
-	for (i = 0; i < nents; i++) {
-		if (sg[i].dma_length == 0)
+	iommu = sdev->bus->iommu;
+
+	bus_addr = sglist[0].dma_address & IO_PAGE_MASK;
+	for (i = 0; i < nelems; i++) {
+		if (!sglist[i].dma_length)
 			break;
 	}
 	i--;
-	size = IO_PAGE_ALIGN(sg[i].dma_address + sg[i].dma_length) - base;
+	npages = (IO_PAGE_ALIGN(sglist[i].dma_address + sglist[i].dma_length)
+		  - bus_addr) >> IO_PAGE_SHIFT;
 
 	spin_lock_irqsave(&iommu->lock, flags);
-	sbus_strbuf_flush(iommu, base, size >> IO_PAGE_SHIFT, direction);
+	sbus_strbuf_flush(iommu, bus_addr, npages, direction);
 	spin_unlock_irqrestore(&iommu->lock, flags);
 }
 
···
 	struct linux_prom64_registers *pr;
 	struct device_node *dp;
 	struct sbus_iommu *iommu;
-	unsigned long regs, tsb_base;
+	unsigned long regs;
 	u64 control;
 	int i;
 
···
 
 	memset(iommu, 0, sizeof(*iommu));
 
-	/* We start with no consistent mappings. */
-	iommu->lowest_consistent_map = CLUSTER_NPAGES;
-
-	for (i = 0; i < NCLUSTERS; i++) {
-		iommu->alloc_info[i].flush = 0;
-		iommu->alloc_info[i].next = 0;
-	}
-
 	/* Setup spinlock. */
 	spin_lock_init(&iommu->lock);
 
···
 	       sbus->portid, regs);
 
 	/* Setup for TSB_SIZE=7, TBW_SIZE=0, MMU_DE=1, MMU_EN=1 */
+	sbus_iommu_table_init(iommu, IO_TSB_SIZE);
+
 	control = upa_readq(iommu->iommu_regs + IOMMU_CONTROL);
 	control = ((7UL << 16UL)	|
 		   (0UL << 2UL)		|
 		   (1UL << 1UL)		|
 		   (1UL << 0UL));
-
-	/* Using the above configuration we need 1MB iommu page
-	 * table (128K ioptes * 8 bytes per iopte).  This is
-	 * page order 7 on UltraSparc.
-	 */
-	tsb_base = __get_free_pages(GFP_ATOMIC, get_order(IO_TSB_SIZE));
-	if (tsb_base == 0UL) {
-		prom_printf("sbus_iommu_init: Fatal error, cannot alloc TSB table.\n");
-		prom_halt();
-	}
-
-	iommu->page_table = (iopte_t *) tsb_base;
-	memset(iommu->page_table, 0, IO_TSB_SIZE);
-
 	upa_writeq(control, iommu->iommu_regs + IOMMU_CONTROL);
 
 	/* Clean out any cruft in the IOMMU using
···
 	upa_readq(iommu->sbus_control_reg);
 
 	/* Give the TSB to SYSIO. */
-	upa_writeq(__pa(tsb_base), iommu->iommu_regs + IOMMU_TSBBASE);
+	upa_writeq(__pa(iommu->page_table), iommu->iommu_regs + IOMMU_TSBBASE);
 
 	/* Setup streaming buffer, DE=1 SB_EN=1 */
 	control = (1UL << 1UL) | (1UL << 0UL);