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Commit 38192d52 authored by David S. Miller's avatar David S. Miller Committed by David S. Miller
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[SPARC64]: Temporarily remove IOMMU merging code. 



Changeset fde6a3c8 ("iommu sg merging:
sparc64: make iommu respect the segment size limits") broke sparc64
because whilst it added the segment limiting code to the first pass of
SG mapping (in prepare_sg()) it did not add matching code to the
second pass handling (in fill_sg())

As a result the two passes disagree where the segment boundaries
should be, resulting in OOPSes, DMA corruption, and corrupted
superblocks.

Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent b3ff81dd

arch/sparc64/kernel/Makefile

+1 −1
Original line number Diff line number Diff line
@@ -11,7 +11,7 @@ obj-y := process.o setup.o cpu.o idprom.o \ 
		   traps.o auxio.o una_asm.o sysfs.o iommu.o \

		   irq.o ptrace.o time.o sys_sparc.o signal.o \

		   unaligned.o central.o pci.o starfire.o semaphore.o \

		   power.o sbus.o iommu_common.o sparc64_ksyms.o chmc.o \

		   power.o sbus.o sparc64_ksyms.o chmc.o \

		   visemul.o prom.o of_device.o hvapi.o sstate.o mdesc.o



obj-$(CONFIG_STACKTRACE) += stacktrace.o

arch/sparc64/kernel/iommu.c

+26 −116
Original line number Diff line number Diff line
@@ -472,94 +472,15 @@ static void dma_4u_unmap_single(struct device *dev, dma_addr_t bus_addr, 
	spin_unlock_irqrestore(&iommu->lock, flags);

}



#define SG_ENT_PHYS_ADDRESS(SG)	(__pa(sg_virt((SG))))



static void fill_sg(iopte_t *iopte, struct scatterlist *sg,

		    int nused, int nelems,

		    unsigned long iopte_protection)

{

	struct scatterlist *dma_sg = sg;

	int i;



	for (i = 0; i < nused; i++) {

		unsigned long pteval = ~0UL;

		u32 dma_npages;



		dma_npages = ((dma_sg->dma_address & (IO_PAGE_SIZE - 1UL)) +

			      dma_sg->dma_length +

			      ((IO_PAGE_SIZE - 1UL))) >> IO_PAGE_SHIFT;

		do {

			unsigned long offset;

			signed int len;



			/* If we are here, we know we have at least one

			 * more page to map.  So walk forward until we

			 * hit a page crossing, and begin creating new

			 * mappings from that spot.

			 */

			for (;;) {

				unsigned long tmp;



				tmp = SG_ENT_PHYS_ADDRESS(sg);

				len = sg->length;

				if (((tmp ^ pteval) >> IO_PAGE_SHIFT) != 0UL) {

					pteval = tmp & IO_PAGE_MASK;

					offset = tmp & (IO_PAGE_SIZE - 1UL);

					break;

				}

				if (((tmp ^ (tmp + len - 1UL)) >> IO_PAGE_SHIFT) != 0UL) {

					pteval = (tmp + IO_PAGE_SIZE) & IO_PAGE_MASK;

					offset = 0UL;

					len -= (IO_PAGE_SIZE - (tmp & (IO_PAGE_SIZE - 1UL)));

					break;

				}

				sg = sg_next(sg);

				nelems--;

			}



			pteval = iopte_protection | (pteval & IOPTE_PAGE);

			while (len > 0) {

				*iopte++ = __iopte(pteval);

				pteval += IO_PAGE_SIZE;

				len -= (IO_PAGE_SIZE - offset);

				offset = 0;

				dma_npages--;

			}



			pteval = (pteval & IOPTE_PAGE) + len;

			sg = sg_next(sg);

			nelems--;



			/* Skip over any tail mappings we've fully mapped,

			 * adjusting pteval along the way.  Stop when we

			 * detect a page crossing event.

			 */

			while (nelems &&

			       (pteval << (64 - IO_PAGE_SHIFT)) != 0UL &&

			       (pteval == SG_ENT_PHYS_ADDRESS(sg)) &&

			       ((pteval ^

				 (SG_ENT_PHYS_ADDRESS(sg) + sg->length - 1UL)) >> IO_PAGE_SHIFT) == 0UL) {

				pteval += sg->length;

				sg = sg_next(sg);

				nelems--;

			}

			if ((pteval << (64 - IO_PAGE_SHIFT)) == 0UL)

				pteval = ~0UL;

		} while (dma_npages != 0);

		dma_sg = sg_next(dma_sg);

	}

}



static int dma_4u_map_sg(struct device *dev, struct scatterlist *sglist,

			 int nelems, enum dma_data_direction direction)

{

	struct iommu *iommu;

	unsigned long flags, ctx, i, npages, iopte_protection;

	struct scatterlist *sg;

	struct strbuf *strbuf;

	unsigned long flags, ctx, npages, iopte_protection;

	struct iommu *iommu;

	iopte_t *base;

	u32 dma_base;

	struct scatterlist *sgtmp;

	int used;



	/* Fast path single entry scatterlists. */

	if (nelems == 1) {
@@ -578,11 +499,7 @@ static int dma_4u_map_sg(struct device *dev, struct scatterlist *sglist, 
	if (unlikely(direction == DMA_NONE))

		goto bad_no_ctx;



	/* Step 1: Prepare scatter list. */



	npages = prepare_sg(dev, sglist, nelems);



	/* Step 2: Allocate a cluster and context, if necessary. */

	npages = calc_npages(sglist, nelems);



	spin_lock_irqsave(&iommu->lock, flags);
@@ -599,18 +516,6 @@ static int dma_4u_map_sg(struct device *dev, struct scatterlist *sglist, 
	dma_base = iommu->page_table_map_base +

		((base - iommu->page_table) << IO_PAGE_SHIFT);



	/* Step 3: Normalize DMA addresses. */

	used = nelems;



	sgtmp = sglist;

	while (used && sgtmp->dma_length) {

		sgtmp->dma_address += dma_base;

		sgtmp = sg_next(sgtmp);

		used--;

	}

	used = nelems - used;



	/* Step 4: Create the mappings. */

	if (strbuf->strbuf_enabled)

		iopte_protection = IOPTE_STREAMING(ctx);

	else
@@ -618,13 +523,27 @@ static int dma_4u_map_sg(struct device *dev, struct scatterlist *sglist, 
	if (direction != DMA_TO_DEVICE)

		iopte_protection |= IOPTE_WRITE;



	fill_sg(base, sglist, used, nelems, iopte_protection);

	for_each_sg(sglist, sg, nelems, i) {

		unsigned long paddr = SG_ENT_PHYS_ADDRESS(sg);

		unsigned long slen = sg->length;

		unsigned long this_npages;



		this_npages = iommu_num_pages(paddr, slen);



#ifdef VERIFY_SG

	verify_sglist(sglist, nelems, base, npages);

#endif

		sg->dma_address = dma_base | (paddr & ~IO_PAGE_MASK);

		sg->dma_length = slen;



	return used;

		paddr &= IO_PAGE_MASK;

		while (this_npages--) {

			iopte_val(*base) = iopte_protection | paddr;



			base++;

			paddr += IO_PAGE_SIZE;

			dma_base += IO_PAGE_SIZE;

		}

	}



	return nelems;



bad:

	iommu_free_ctx(iommu, ctx);
@@ -637,11 +556,10 @@ static int dma_4u_map_sg(struct device *dev, struct scatterlist *sglist, 
static void dma_4u_unmap_sg(struct device *dev, struct scatterlist *sglist,

			    int nelems, enum dma_data_direction direction)

{

	struct iommu *iommu;

	unsigned long flags, ctx, i, npages;

	struct strbuf *strbuf;

	struct iommu *iommu;

	iopte_t *base;

	unsigned long flags, ctx, i, npages;

	struct scatterlist *sg, *sgprv;

	u32 bus_addr;



	if (unlikely(direction == DMA_NONE)) {
@@ -654,15 +572,7 @@ static void dma_4u_unmap_sg(struct device *dev, struct scatterlist *sglist, 


	bus_addr = sglist->dma_address & IO_PAGE_MASK;



	sgprv = NULL;

	for_each_sg(sglist, sg, nelems, i) {

		if (sg->dma_length == 0)

			break;

		sgprv = sg;

	}



	npages = (IO_PAGE_ALIGN(sgprv->dma_address + sgprv->dma_length) -

		  bus_addr) >> IO_PAGE_SHIFT;

	npages = calc_npages(sglist, nelems);



	base = iommu->page_table +

		((bus_addr - iommu->page_table_map_base) >> IO_PAGE_SHIFT);

arch/sparc64/kernel/iommu_common.c

deleted100644 → 0
+0 −248
Original line number Diff line number Diff line 
/* $Id: iommu_common.c,v 1.9 2001/12/17 07:05:09 davem Exp $

 * iommu_common.c: UltraSparc SBUS/PCI common iommu code.

 *

 * Copyright (C) 1999 David S. Miller (davem@redhat.com)

 */



#include <linux/dma-mapping.h>

#include "iommu_common.h"



/* You are _strongly_ advised to enable the following debugging code

 * any time you make changes to the sg code below, run it for a while

 * with filesystems mounted read-only before buying the farm... -DaveM

 */



#ifdef VERIFY_SG

static int verify_lengths(struct scatterlist *sglist, int nents, int npages)

{

	int sg_len, dma_len;

	int i, pgcount;

	struct scatterlist *sg;



	sg_len = 0;

	for_each_sg(sglist, sg, nents, i)

		sg_len += sg->length;



	dma_len = 0;

	for_each_sg(sglist, sg, nents, i) {

		if (!sg->dma_length)

			break;

		dma_len += sg->dma_length;

	}



	if (sg_len != dma_len) {

		printk("verify_lengths: Error, different, sg[%d] dma[%d]\n",

		       sg_len, dma_len);

		return -1;

	}



	pgcount = 0;

	for_each_sg(sglist, sg, nents, i) {

		unsigned long start, end;



		if (!sg->dma_length)

			break;



		start = sg->dma_address;

		start = start & IO_PAGE_MASK;



		end = sg->dma_address + sg->dma_length;

		end = (end + (IO_PAGE_SIZE - 1)) & IO_PAGE_MASK;



		pgcount += ((end - start) >> IO_PAGE_SHIFT);

	}



	if (pgcount != npages) {

		printk("verify_lengths: Error, page count wrong, "

		       "npages[%d] pgcount[%d]\n",

		       npages, pgcount);

		return -1;

	}



	/* This test passes... */

	return 0;

}



static int verify_one_map(struct scatterlist *dma_sg, struct scatterlist **__sg, int nents, iopte_t **__iopte)

{

	struct scatterlist *sg = *__sg;

	iopte_t *iopte = *__iopte;

	u32 dlen = dma_sg->dma_length;

	u32 daddr;

	unsigned int sglen;

	unsigned long sgaddr;



	daddr = dma_sg->dma_address;

	sglen = sg->length;

	sgaddr = (unsigned long) sg_virt(sg);

	while (dlen > 0) {

		unsigned long paddr;



		/* SG and DMA_SG must begin at the same sub-page boundary. */

		if ((sgaddr & ~IO_PAGE_MASK) != (daddr & ~IO_PAGE_MASK)) {

			printk("verify_one_map: Wrong start offset "

			       "sg[%08lx] dma[%08x]\n",

			       sgaddr, daddr);

			nents = -1;

			goto out;

		}



		/* Verify the IOPTE points to the right page. */

		paddr = iopte_val(*iopte) & IOPTE_PAGE;

		if ((paddr + PAGE_OFFSET) != (sgaddr & IO_PAGE_MASK)) {

			printk("verify_one_map: IOPTE[%08lx] maps the "

			       "wrong page, should be [%08lx]\n",

			       iopte_val(*iopte), (sgaddr & IO_PAGE_MASK) - PAGE_OFFSET);

			nents = -1;

			goto out;

		}



		/* If this SG crosses a page, adjust to that next page

		 * boundary and loop.

		 */

		if ((sgaddr & IO_PAGE_MASK) ^ ((sgaddr + sglen - 1) & IO_PAGE_MASK)) {

			unsigned long next_page, diff;



			next_page = (sgaddr + IO_PAGE_SIZE) & IO_PAGE_MASK;

			diff = next_page - sgaddr;

			sgaddr += diff;

			daddr += diff;

			sglen -= diff;

			dlen -= diff;

			if (dlen > 0)

				iopte++;

			continue;

		}



		/* SG wholly consumed within this page. */

		daddr += sglen;

		dlen -= sglen;



		if (dlen > 0 && ((daddr & ~IO_PAGE_MASK) == 0))

			iopte++;



		sg = sg_next(sg);

		if (--nents <= 0)

			break;

		sgaddr = (unsigned long) sg_virt(sg);

		sglen = sg->length;

	}

	if (dlen < 0) {

		/* Transfer overrun, big problems. */

		printk("verify_one_map: Transfer overrun by %d bytes.\n",

		       -dlen);

		nents = -1;

	} else {

		/* Advance to next dma_sg implies that the next iopte will

		 * begin it.

		 */

		iopte++;

	}



out:

	*__sg = sg;

	*__iopte = iopte;

	return nents;

}



static int verify_maps(struct scatterlist *sg, int nents, iopte_t *iopte)

{

	struct scatterlist *dma_sg = sg;

	struct scatterlist *orig_dma_sg = dma_sg;

	int orig_nents = nents;



	for (;;) {

		nents = verify_one_map(dma_sg, &sg, nents, &iopte);

		if (nents <= 0)

			break;

		dma_sg = sg_next(dma_sg);

		if (dma_sg->dma_length == 0)

			break;

	}



	if (nents > 0) {

		printk("verify_maps: dma maps consumed by some sgs remain (%d)\n",

		       nents);

		return -1;

	}



	if (nents < 0) {

		printk("verify_maps: Error, messed up mappings, "

		       "at sg %d dma_sg %d\n",

		       (int) (orig_nents + nents), (int) (dma_sg - orig_dma_sg));

		return -1;

	}



	/* This test passes... */

	return 0;

}



void verify_sglist(struct scatterlist *sglist, int nents, iopte_t *iopte, int npages)

{

	struct scatterlist *sg;



	if (verify_lengths(sglist, nents, npages) < 0 ||

	    verify_maps(sglist, nents, iopte) < 0) {

		int i;



		printk("verify_sglist: Crap, messed up mappings, dumping, iodma at ");

		printk("%016lx.\n", sglist->dma_address & IO_PAGE_MASK);



		for_each_sg(sglist, sg, nents, i) {

			printk("sg(%d): page_addr(%p) off(%x) length(%x) "

			       "dma_address[%016x] dma_length[%016x]\n",

			       i,

			       page_address(sg_page(sg)), sg->offset,

			       sg->length,

			       sg->dma_address, sg->dma_length);

		}

	}



	/* Seems to be ok */

}

#endif



unsigned long prepare_sg(struct device *dev, struct scatterlist *sg, int nents)

{

	struct scatterlist *dma_sg = sg;

	unsigned long prev;

	u32 dent_addr, dent_len;

	unsigned int max_seg_size;



	prev  = (unsigned long) sg_virt(sg);

	prev += (unsigned long) (dent_len = sg->length);

	dent_addr = (u32) ((unsigned long)(sg_virt(sg)) & (IO_PAGE_SIZE - 1UL));

	max_seg_size = dma_get_max_seg_size(dev);

	while (--nents) {

		unsigned long addr;



		sg = sg_next(sg);

		addr = (unsigned long) sg_virt(sg);

		if (! VCONTIG(prev, addr) ||

			dent_len + sg->length > max_seg_size) {

			dma_sg->dma_address = dent_addr;

			dma_sg->dma_length = dent_len;

			dma_sg = sg_next(dma_sg);



			dent_addr = ((dent_addr +

				      dent_len +

				      (IO_PAGE_SIZE - 1UL)) >> IO_PAGE_SHIFT);

			dent_addr <<= IO_PAGE_SHIFT;

			dent_addr += addr & (IO_PAGE_SIZE - 1UL);

			dent_len = 0;

		}

		dent_len += sg->length;

		prev = addr + sg->length;

	}

	dma_sg->dma_address = dent_addr;

	dma_sg->dma_length = dent_len;



	if (dma_sg != sg) {

		dma_sg = sg_next(dma_sg);

		dma_sg->dma_length = 0;

	}



	return ((unsigned long) dent_addr +

		(unsigned long) dent_len +

		(IO_PAGE_SIZE - 1UL)) >> IO_PAGE_SHIFT;

}

arch/sparc64/kernel/iommu_common.h

+26 −0
Original line number Diff line number Diff line
@@ -30,6 +30,32 @@ 
 */

#define IOMMU_PAGE_SHIFT		13



#define SG_ENT_PHYS_ADDRESS(SG)	(__pa(sg_virt((SG))))



static inline unsigned long iommu_num_pages(unsigned long vaddr,

					    unsigned long slen)

{

	unsigned long npages;



	npages = IO_PAGE_ALIGN(vaddr + slen) - (vaddr & IO_PAGE_MASK);

	npages >>= IO_PAGE_SHIFT;



	return npages;

}



static inline unsigned long calc_npages(struct scatterlist *sglist, int nelems)

{

	unsigned long i, npages = 0;

	struct scatterlist *sg;



	for_each_sg(sglist, sg, nelems, i) {

		unsigned long paddr = SG_ENT_PHYS_ADDRESS(sg);

		npages += iommu_num_pages(paddr, sg->length);

	}



	return npages;

}



/* You are _strongly_ advised to enable the following debugging code

 * any time you make changes to the sg code below, run it for a while

 * with filesystems mounted read-only before buying the farm... -DaveM

arch/sparc64/kernel/pci_sun4v.c

+39 −131
Original line number Diff line number Diff line
@@ -365,113 +365,14 @@ static void dma_4v_unmap_single(struct device *dev, dma_addr_t bus_addr, 
	spin_unlock_irqrestore(&iommu->lock, flags);

}



#define SG_ENT_PHYS_ADDRESS(SG)	(__pa(sg_virt((SG))))



static long fill_sg(long entry, struct device *dev,

		    struct scatterlist *sg,

		    int nused, int nelems, unsigned long prot)

{

	struct scatterlist *dma_sg = sg;

	unsigned long flags;

	int i;



	local_irq_save(flags);



	iommu_batch_start(dev, prot, entry);



	for (i = 0; i < nused; i++) {

		unsigned long pteval = ~0UL;

		u32 dma_npages;



		dma_npages = ((dma_sg->dma_address & (IO_PAGE_SIZE - 1UL)) +

			      dma_sg->dma_length +

			      ((IO_PAGE_SIZE - 1UL))) >> IO_PAGE_SHIFT;

		do {

			unsigned long offset;

			signed int len;



			/* If we are here, we know we have at least one

			 * more page to map.  So walk forward until we

			 * hit a page crossing, and begin creating new

			 * mappings from that spot.

			 */

			for (;;) {

				unsigned long tmp;



				tmp = SG_ENT_PHYS_ADDRESS(sg);

				len = sg->length;

				if (((tmp ^ pteval) >> IO_PAGE_SHIFT) != 0UL) {

					pteval = tmp & IO_PAGE_MASK;

					offset = tmp & (IO_PAGE_SIZE - 1UL);

					break;

				}

				if (((tmp ^ (tmp + len - 1UL)) >> IO_PAGE_SHIFT) != 0UL) {

					pteval = (tmp + IO_PAGE_SIZE) & IO_PAGE_MASK;

					offset = 0UL;

					len -= (IO_PAGE_SIZE - (tmp & (IO_PAGE_SIZE - 1UL)));

					break;

				}

				sg = sg_next(sg);

				nelems--;

			}



			pteval = (pteval & IOPTE_PAGE);

			while (len > 0) {

				long err;



				err = iommu_batch_add(pteval);

				if (unlikely(err < 0L))

					goto iommu_map_failed;



				pteval += IO_PAGE_SIZE;

				len -= (IO_PAGE_SIZE - offset);

				offset = 0;

				dma_npages--;

			}



			pteval = (pteval & IOPTE_PAGE) + len;

			sg = sg_next(sg);

			nelems--;



			/* Skip over any tail mappings we've fully mapped,

			 * adjusting pteval along the way.  Stop when we

			 * detect a page crossing event.

			 */

			while (nelems &&

			       (pteval << (64 - IO_PAGE_SHIFT)) != 0UL &&

			       (pteval == SG_ENT_PHYS_ADDRESS(sg)) &&

			       ((pteval ^

				 (SG_ENT_PHYS_ADDRESS(sg) + sg->length - 1UL)) >> IO_PAGE_SHIFT) == 0UL) {

				pteval += sg->length;

				sg = sg_next(sg);

				nelems--;

			}

			if ((pteval << (64 - IO_PAGE_SHIFT)) == 0UL)

				pteval = ~0UL;

		} while (dma_npages != 0);

		dma_sg = sg_next(dma_sg);

	}



	if (unlikely(iommu_batch_end() < 0L))

		goto iommu_map_failed;



	local_irq_restore(flags);

	return 0;



iommu_map_failed:

	local_irq_restore(flags);

	return -1L;

}



static int dma_4v_map_sg(struct device *dev, struct scatterlist *sglist,

			 int nelems, enum dma_data_direction direction)

{

	unsigned long flags, npages, i, prot;

	struct scatterlist *sg;

	struct iommu *iommu;

	unsigned long flags, npages, prot;

	u32 dma_base;

	struct scatterlist *sgtmp;

	long entry, err;

	int used;

	u32 dma_base;



	/* Fast path single entry scatterlists. */

	if (nelems == 1) {
@@ -489,10 +390,8 @@ static int dma_4v_map_sg(struct device *dev, struct scatterlist *sglist, 
	if (unlikely(direction == DMA_NONE))

		goto bad;



	/* Step 1: Prepare scatter list. */

	npages = prepare_sg(dev, sglist, nelems);

	npages = calc_npages(sglist, nelems);



	/* Step 2: Allocate a cluster and context, if necessary. */

	spin_lock_irqsave(&iommu->lock, flags);

	entry = arena_alloc(&iommu->arena, npages);

	spin_unlock_irqrestore(&iommu->lock, flags);
@@ -503,27 +402,45 @@ static int dma_4v_map_sg(struct device *dev, struct scatterlist *sglist, 
	dma_base = iommu->page_table_map_base +

		(entry << IO_PAGE_SHIFT);



	/* Step 3: Normalize DMA addresses. */

	used = nelems;



	sgtmp = sglist;

	while (used && sgtmp->dma_length) {

		sgtmp->dma_address += dma_base;

		sgtmp = sg_next(sgtmp);

		used--;

	}

	used = nelems - used;



	/* Step 4: Create the mappings. */

	prot = HV_PCI_MAP_ATTR_READ;

	if (direction != DMA_TO_DEVICE)

		prot |= HV_PCI_MAP_ATTR_WRITE;



	err = fill_sg(entry, dev, sglist, used, nelems, prot);

	local_irq_save(flags);



	iommu_batch_start(dev, prot, entry);



	for_each_sg(sglist, sg, nelems, i) {

		unsigned long paddr = SG_ENT_PHYS_ADDRESS(sg);

		unsigned long slen = sg->length;

		unsigned long this_npages;



		this_npages = iommu_num_pages(paddr, slen);



		sg->dma_address = dma_base | (paddr & ~IO_PAGE_MASK);

		sg->dma_length = slen;



		paddr &= IO_PAGE_MASK;

		while (this_npages--) {

			err = iommu_batch_add(paddr);

			if (unlikely(err < 0L)) {

				local_irq_restore(flags);

				goto iommu_map_failed;

			}



			paddr += IO_PAGE_SIZE;

			dma_base += IO_PAGE_SIZE;

		}

	}



	err = iommu_batch_end();



	local_irq_restore(flags);



	if (unlikely(err < 0L))

		goto iommu_map_failed;



	return used;

	return nelems;



bad:

	if (printk_ratelimit())
@@ -541,12 +458,11 @@ static int dma_4v_map_sg(struct device *dev, struct scatterlist *sglist, 
static void dma_4v_unmap_sg(struct device *dev, struct scatterlist *sglist,

			    int nelems, enum dma_data_direction direction)

{

	unsigned long flags, npages;

	struct pci_pbm_info *pbm;

	u32 devhandle, bus_addr;

	struct iommu *iommu;

	unsigned long flags, i, npages;

	struct scatterlist *sg, *sgprv;

	long entry;

	u32 devhandle, bus_addr;



	if (unlikely(direction == DMA_NONE)) {

		if (printk_ratelimit())
@@ -558,16 +474,8 @@ static void dma_4v_unmap_sg(struct device *dev, struct scatterlist *sglist, 
	devhandle = pbm->devhandle;

	

	bus_addr = sglist->dma_address & IO_PAGE_MASK;

	sgprv = NULL;

	for_each_sg(sglist, sg, nelems, i) {

		if (sg->dma_length == 0)

			break;



		sgprv = sg;

	}



	npages = (IO_PAGE_ALIGN(sgprv->dma_address + sgprv->dma_length) -

		  bus_addr) >> IO_PAGE_SHIFT;

	npages = calc_npages(sglist, nelems);



	entry = ((bus_addr - iommu->page_table_map_base) >> IO_PAGE_SHIFT);