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iommu.c

/* iommu.c: Generic sparc64 IOMMU support.
 *
 * Copyright (C) 1999, 2007 David S. Miller (davem@davemloft.net)
 * Copyright (C) 1999, 2000 Jakub Jelinek (jakub@redhat.com)
 */

#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/delay.h>
#include <linux/device.h>
#include <linux/dma-mapping.h>
#include <linux/errno.h>

#ifdef CONFIG_PCI
#include <linux/pci.h>
#endif

#include <asm/iommu.h>

#include "iommu_common.h"

#define STC_CTXMATCH_ADDR(STC, CTX) \
      ((STC)->strbuf_ctxmatch_base + ((CTX) << 3))
#define STC_FLUSHFLAG_INIT(STC) \
      (*((STC)->strbuf_flushflag) = 0UL)
#define STC_FLUSHFLAG_SET(STC) \
      (*((STC)->strbuf_flushflag) != 0UL)

#define iommu_read(__reg) \
({    u64 __ret; \
      __asm__ __volatile__("ldxa [%1] %2, %0" \
                       : "=r" (__ret) \
                       : "r" (__reg), "i" (ASI_PHYS_BYPASS_EC_E) \
                       : "memory"); \
      __ret; \
})
#define iommu_write(__reg, __val) \
      __asm__ __volatile__("stxa %0, [%1] %2" \
                       : /* no outputs */ \
                       : "r" (__val), "r" (__reg), \
                         "i" (ASI_PHYS_BYPASS_EC_E))

/* Must be invoked under the IOMMU lock. */
static void __iommu_flushall(struct iommu *iommu)
{
      if (iommu->iommu_flushinv) {
            iommu_write(iommu->iommu_flushinv, ~(u64)0);
      } else {
            unsigned long tag;
            int entry;

            tag = iommu->iommu_tags;
            for (entry = 0; entry < 16; entry++) {
                  iommu_write(tag, 0);
                  tag += 8;
            }

            /* Ensure completion of previous PIO writes. */
            (void) iommu_read(iommu->write_complete_reg);
      }
}

#define IOPTE_CONSISTENT(CTX) \
      (IOPTE_VALID | IOPTE_CACHE | \
       (((CTX) << 47) & IOPTE_CONTEXT))

#define IOPTE_STREAMING(CTX) \
      (IOPTE_CONSISTENT(CTX) | IOPTE_STBUF)

/* Existing mappings are never marked invalid, instead they
 * are pointed to a dummy page.
 */
#define IOPTE_IS_DUMMY(iommu, iopte)      \
      ((iopte_val(*iopte) & IOPTE_PAGE) == (iommu)->dummy_page_pa)

static inline void iopte_make_dummy(struct iommu *iommu, iopte_t *iopte)
{
      unsigned long val = iopte_val(*iopte);

      val &= ~IOPTE_PAGE;
      val |= iommu->dummy_page_pa;

      iopte_val(*iopte) = val;
}

/* Based largely upon the ppc64 iommu allocator.  */
static long arena_alloc(struct iommu *iommu, unsigned long npages)
{
      struct iommu_arena *arena = &iommu->arena;
      unsigned long n, i, start, end, limit;
      int pass;

      limit = arena->limit;
      start = arena->hint;
      pass = 0;

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);
                  pass++;
                  goto again;
            } else {
                  /* Scanned the whole thing, give up. */
                  return -1;
            }
      }

      for (i = n; i < end; i++) {
            if (test_bit(i, arena->map)) {
                  start = i + 1;
                  goto again;
            }
      }

      for (i = n; i < end; i++)
            __set_bit(i, arena->map);

      arena->hint = end;

      return n;
}

static void arena_free(struct iommu_arena *arena, unsigned long base, unsigned long npages)
{
      unsigned long i;

      for (i = base; i < (base + npages); i++)
            __clear_bit(i, arena->map);
}

int iommu_table_init(struct iommu *iommu, int tsbsize,
                 u32 dma_offset, u32 dma_addr_mask)
{
      unsigned long i, tsbbase, order, sz, num_tsb_entries;

      num_tsb_entries = tsbsize / sizeof(iopte_t);

      /* Setup initial software IOMMU state. */
      spin_lock_init(&iommu->lock);
      iommu->ctx_lowest_free = 1;
      iommu->page_table_map_base = dma_offset;
      iommu->dma_addr_mask = dma_addr_mask;

      /* 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) {
            printk(KERN_ERR "IOMMU: Error, kmalloc(arena.map) failed.\n");
            return -ENOMEM;
      }
      iommu->arena.limit = num_tsb_entries;

      /* Allocate and initialize the dummy page which we
       * set inactive IO PTEs to point to.
       */
      iommu->dummy_page = __get_free_pages(GFP_KERNEL, 0);
      if (!iommu->dummy_page) {
            printk(KERN_ERR "IOMMU: Error, gfp(dummy_page) failed.\n");
            goto out_free_map;
      }
      memset((void *)iommu->dummy_page, 0, PAGE_SIZE);
      iommu->dummy_page_pa = (unsigned long) __pa(iommu->dummy_page);

      /* Now allocate and setup the IOMMU page table itself.  */
      order = get_order(tsbsize);
      tsbbase = __get_free_pages(GFP_KERNEL, order);
      if (!tsbbase) {
            printk(KERN_ERR "IOMMU: Error, gfp(tsb) failed.\n");
            goto out_free_dummy_page;
      }
      iommu->page_table = (iopte_t *)tsbbase;

      for (i = 0; i < num_tsb_entries; i++)
            iopte_make_dummy(iommu, &iommu->page_table[i]);

      return 0;

out_free_dummy_page:
      free_page(iommu->dummy_page);
      iommu->dummy_page = 0UL;

out_free_map:
      kfree(iommu->arena.map);
      iommu->arena.map = NULL;

      return -ENOMEM;
}

static inline iopte_t *alloc_npages(struct iommu *iommu, unsigned long npages)
{
      long entry;

      entry = arena_alloc(iommu, npages);
      if (unlikely(entry < 0))
            return NULL;

      return iommu->page_table + entry;
}

static inline void free_npages(struct iommu *iommu, dma_addr_t base, unsigned long npages)
{
      arena_free(&iommu->arena, base >> IO_PAGE_SHIFT, npages);
}

static int iommu_alloc_ctx(struct iommu *iommu)
{
      int lowest = iommu->ctx_lowest_free;
      int sz = IOMMU_NUM_CTXS - lowest;
      int n = find_next_zero_bit(iommu->ctx_bitmap, sz, lowest);

      if (unlikely(n == sz)) {
            n = find_next_zero_bit(iommu->ctx_bitmap, lowest, 1);
            if (unlikely(n == lowest)) {
                  printk(KERN_WARNING "IOMMU: Ran out of contexts.\n");
                  n = 0;
            }
      }
      if (n)
            __set_bit(n, iommu->ctx_bitmap);

      return n;
}

static inline void iommu_free_ctx(struct iommu *iommu, int ctx)
{
      if (likely(ctx)) {
            __clear_bit(ctx, iommu->ctx_bitmap);
            if (ctx < iommu->ctx_lowest_free)
                  iommu->ctx_lowest_free = ctx;
      }
}

static void *dma_4u_alloc_coherent(struct device *dev, size_t size,
                           dma_addr_t *dma_addrp, gfp_t gfp)
{
      struct iommu *iommu;
      iopte_t *iopte;
      unsigned long flags, order, first_page;
      void *ret;
      int npages;

      size = IO_PAGE_ALIGN(size);
      order = get_order(size);
      if (order >= 10)
            return NULL;

      first_page = __get_free_pages(gfp, order);
      if (first_page == 0UL)
            return NULL;
      memset((char *)first_page, 0, PAGE_SIZE << order);

      iommu = dev->archdata.iommu;

      spin_lock_irqsave(&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;
      }

      *dma_addrp = (iommu->page_table_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_val(*iopte) = (IOPTE_CONSISTENT(0UL) |
                             IOPTE_WRITE |
                             (first_page & IOPTE_PAGE));
            iopte++;
            first_page += IO_PAGE_SIZE;
      }

      return ret;
}

static void dma_4u_free_coherent(struct device *dev, size_t size,
                         void *cpu, dma_addr_t dvma)
{
      struct iommu *iommu;
      iopte_t *iopte;
      unsigned long flags, order, npages;

      npages = IO_PAGE_ALIGN(size) >> IO_PAGE_SHIFT;
      iommu = dev->archdata.iommu;
      iopte = iommu->page_table +
            ((dvma - iommu->page_table_map_base) >> IO_PAGE_SHIFT);

      spin_lock_irqsave(&iommu->lock, flags);

      free_npages(iommu, dvma - iommu->page_table_map_base, npages);

      spin_unlock_irqrestore(&iommu->lock, flags);

      order = get_order(size);
      if (order < 10)
            free_pages((unsigned long)cpu, order);
}

static dma_addr_t dma_4u_map_single(struct device *dev, void *ptr, size_t sz,
                            enum dma_data_direction direction)
{
      struct iommu *iommu;
      struct strbuf *strbuf;
      iopte_t *base;
      unsigned long flags, npages, oaddr;
      unsigned long i, base_paddr, ctx;
      u32 bus_addr, ret;
      unsigned long iopte_protection;

      iommu = dev->archdata.iommu;
      strbuf = dev->archdata.stc;

      if (unlikely(direction == DMA_NONE))
            goto bad_no_ctx;

      oaddr = (unsigned long)ptr;
      npages = IO_PAGE_ALIGN(oaddr + sz) - (oaddr & IO_PAGE_MASK);
      npages >>= IO_PAGE_SHIFT;

      spin_lock_irqsave(&iommu->lock, flags);
      base = alloc_npages(iommu, npages);
      ctx = 0;
      if (iommu->iommu_ctxflush)
            ctx = iommu_alloc_ctx(iommu);
      spin_unlock_irqrestore(&iommu->lock, flags);

      if (unlikely(!base))
            goto bad;

      bus_addr = (iommu->page_table_map_base +
                ((base - iommu->page_table) << IO_PAGE_SHIFT));
      ret = bus_addr | (oaddr & ~IO_PAGE_MASK);
      base_paddr = __pa(oaddr & IO_PAGE_MASK);
      if (strbuf->strbuf_enabled)
            iopte_protection = IOPTE_STREAMING(ctx);
      else
            iopte_protection = IOPTE_CONSISTENT(ctx);
      if (direction != DMA_TO_DEVICE)
            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;

bad:
      iommu_free_ctx(iommu, ctx);
bad_no_ctx:
      if (printk_ratelimit())
            WARN_ON(1);
      return DMA_ERROR_CODE;
}

static void strbuf_flush(struct strbuf *strbuf, struct iommu *iommu,
                   u32 vaddr, unsigned long ctx, unsigned long npages,
                   enum dma_data_direction direction)
{
      int limit;

      if (strbuf->strbuf_ctxflush &&
          iommu->iommu_ctxflush) {
            unsigned long matchreg, flushreg;
            u64 val;

            flushreg = strbuf->strbuf_ctxflush;
            matchreg = STC_CTXMATCH_ADDR(strbuf, ctx);

            iommu_write(flushreg, ctx);
            val = iommu_read(matchreg);
            val &= 0xffff;
            if (!val)
                  goto do_flush_sync;

            while (val) {
                  if (val & 0x1)
                        iommu_write(flushreg, ctx);
                  val >>= 1;
            }
            val = iommu_read(matchreg);
            if (unlikely(val)) {
                  printk(KERN_WARNING "strbuf_flush: ctx flush "
                         "timeout matchreg[%lx] ctx[%lx]\n",
                         val, ctx);
                  goto do_page_flush;
            }
      } else {
            unsigned long i;

      do_page_flush:
            for (i = 0; i < npages; i++, vaddr += IO_PAGE_SIZE)
                  iommu_write(strbuf->strbuf_pflush, vaddr);
      }

do_flush_sync:
      /* If the device could not have possibly put dirty data into
       * the streaming cache, no flush-flag synchronization needs
       * to be performed.
       */
      if (direction == DMA_TO_DEVICE)
            return;

      STC_FLUSHFLAG_INIT(strbuf);
      iommu_write(strbuf->strbuf_fsync, strbuf->strbuf_flushflag_pa);
      (void) iommu_read(iommu->write_complete_reg);

      limit = 100000;
      while (!STC_FLUSHFLAG_SET(strbuf)) {
            limit--;
            if (!limit)
                  break;
            udelay(1);
            rmb();
      }
      if (!limit)
            printk(KERN_WARNING "strbuf_flush: flushflag timeout "
                   "vaddr[%08x] ctx[%lx] npages[%ld]\n",
                   vaddr, ctx, npages);
}

static void dma_4u_unmap_single(struct device *dev, dma_addr_t bus_addr,
                        size_t sz, enum dma_data_direction direction)
{
      struct iommu *iommu;
      struct strbuf *strbuf;
      iopte_t *base;
      unsigned long flags, npages, ctx, i;

      if (unlikely(direction == DMA_NONE)) {
            if (printk_ratelimit())
                  WARN_ON(1);
            return;
      }

      iommu = dev->archdata.iommu;
      strbuf = dev->archdata.stc;

      npages = IO_PAGE_ALIGN(bus_addr + sz) - (bus_addr & IO_PAGE_MASK);
      npages >>= IO_PAGE_SHIFT;
      base = iommu->page_table +
            ((bus_addr - iommu->page_table_map_base) >> IO_PAGE_SHIFT);
      bus_addr &= IO_PAGE_MASK;

      spin_lock_irqsave(&iommu->lock, flags);

      /* Record the context, if any. */
      ctx = 0;
      if (iommu->iommu_ctxflush)
            ctx = (iopte_val(*base) & IOPTE_CONTEXT) >> 47UL;

      /* Step 1: Kick data out of streaming buffers if necessary. */
      if (strbuf->strbuf_enabled)
            strbuf_flush(strbuf, iommu, bus_addr, ctx,
                       npages, direction);

      /* Step 2: Clear out TSB entries. */
      for (i = 0; i < npages; i++)
            iopte_make_dummy(iommu, base + i);

      free_npages(iommu, bus_addr - iommu->page_table_map_base, npages);

      iommu_free_ctx(iommu, ctx);

      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;
      struct strbuf *strbuf;
      unsigned long flags, ctx, npages, iopte_protection;
      iopte_t *base;
      u32 dma_base;
      struct scatterlist *sgtmp;
      int used;

      /* Fast path single entry scatterlists. */
      if (nelems == 1) {
            sglist->dma_address =
                  dma_4u_map_single(dev, sg_virt(sglist),
                                sglist->length, direction);
            if (unlikely(sglist->dma_address == DMA_ERROR_CODE))
                  return 0;
            sglist->dma_length = sglist->length;
            return 1;
      }

      iommu = dev->archdata.iommu;
      strbuf = dev->archdata.stc;

      if (unlikely(direction == DMA_NONE))
            goto bad_no_ctx;

      /* Step 1: Prepare scatter list. */

      npages = prepare_sg(sglist, nelems);

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

      spin_lock_irqsave(&iommu->lock, flags);

      base = alloc_npages(iommu, npages);
      ctx = 0;
      if (iommu->iommu_ctxflush)
            ctx = iommu_alloc_ctx(iommu);

      spin_unlock_irqrestore(&iommu->lock, flags);

      if (base == NULL)
            goto bad;

      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
            iopte_protection = IOPTE_CONSISTENT(ctx);
      if (direction != DMA_TO_DEVICE)
            iopte_protection |= IOPTE_WRITE;

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

#ifdef VERIFY_SG
      verify_sglist(sglist, nelems, base, npages);
#endif

      return used;

bad:
      iommu_free_ctx(iommu, ctx);
bad_no_ctx:
      if (printk_ratelimit())
            WARN_ON(1);
      return 0;
}

static void dma_4u_unmap_sg(struct device *dev, struct scatterlist *sglist,
                      int nelems, enum dma_data_direction direction)
{
      struct iommu *iommu;
      struct strbuf *strbuf;
      iopte_t *base;
      unsigned long flags, ctx, i, npages;
      struct scatterlist *sg, *sgprv;
      u32 bus_addr;

      if (unlikely(direction == DMA_NONE)) {
            if (printk_ratelimit())
                  WARN_ON(1);
      }

      iommu = dev->archdata.iommu;
      strbuf = dev->archdata.stc;

      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;

      base = iommu->page_table +
            ((bus_addr - iommu->page_table_map_base) >> IO_PAGE_SHIFT);

      spin_lock_irqsave(&iommu->lock, flags);

      /* Record the context, if any. */
      ctx = 0;
      if (iommu->iommu_ctxflush)
            ctx = (iopte_val(*base) & IOPTE_CONTEXT) >> 47UL;

      /* Step 1: Kick data out of streaming buffers if necessary. */
      if (strbuf->strbuf_enabled)
            strbuf_flush(strbuf, iommu, bus_addr, ctx, npages, direction);

      /* Step 2: Clear out the TSB entries. */
      for (i = 0; i < npages; i++)
            iopte_make_dummy(iommu, base + i);

      free_npages(iommu, bus_addr - iommu->page_table_map_base, npages);

      iommu_free_ctx(iommu, ctx);

      spin_unlock_irqrestore(&iommu->lock, flags);
}

static void dma_4u_sync_single_for_cpu(struct device *dev,
                               dma_addr_t bus_addr, size_t sz,
                               enum dma_data_direction direction)
{
      struct iommu *iommu;
      struct strbuf *strbuf;
      unsigned long flags, ctx, npages;

      iommu = dev->archdata.iommu;
      strbuf = dev->archdata.stc;

      if (!strbuf->strbuf_enabled)
            return;

      spin_lock_irqsave(&iommu->lock, flags);

      npages = IO_PAGE_ALIGN(bus_addr + sz) - (bus_addr & IO_PAGE_MASK);
      npages >>= IO_PAGE_SHIFT;
      bus_addr &= IO_PAGE_MASK;

      /* Step 1: Record the context, if any. */
      ctx = 0;
      if (iommu->iommu_ctxflush &&
          strbuf->strbuf_ctxflush) {
            iopte_t *iopte;

            iopte = iommu->page_table +
                  ((bus_addr - iommu->page_table_map_base)>>IO_PAGE_SHIFT);
            ctx = (iopte_val(*iopte) & IOPTE_CONTEXT) >> 47UL;
      }

      /* Step 2: Kick data out of streaming buffers. */
      strbuf_flush(strbuf, iommu, bus_addr, ctx, npages, direction);

      spin_unlock_irqrestore(&iommu->lock, flags);
}

static void dma_4u_sync_sg_for_cpu(struct device *dev,
                           struct scatterlist *sglist, int nelems,
                           enum dma_data_direction direction)
{
      struct iommu *iommu;
      struct strbuf *strbuf;
      unsigned long flags, ctx, npages, i;
      struct scatterlist *sg, *sgprv;
      u32 bus_addr;

      iommu = dev->archdata.iommu;
      strbuf = dev->archdata.stc;

      if (!strbuf->strbuf_enabled)
            return;

      spin_lock_irqsave(&iommu->lock, flags);

      /* Step 1: Record the context, if any. */
      ctx = 0;
      if (iommu->iommu_ctxflush &&
          strbuf->strbuf_ctxflush) {
            iopte_t *iopte;

            iopte = iommu->page_table +
                  ((sglist[0].dma_address - iommu->page_table_map_base) >> IO_PAGE_SHIFT);
            ctx = (iopte_val(*iopte) & IOPTE_CONTEXT) >> 47UL;
      }

      /* Step 2: Kick data out of streaming buffers. */
      bus_addr = sglist[0].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;
      strbuf_flush(strbuf, iommu, bus_addr, ctx, npages, direction);

      spin_unlock_irqrestore(&iommu->lock, flags);
}

const struct dma_ops sun4u_dma_ops = {
      .alloc_coherent         = dma_4u_alloc_coherent,
      .free_coherent          = dma_4u_free_coherent,
      .map_single       = dma_4u_map_single,
      .unmap_single           = dma_4u_unmap_single,
      .map_sg                 = dma_4u_map_sg,
      .unmap_sg         = dma_4u_unmap_sg,
      .sync_single_for_cpu    = dma_4u_sync_single_for_cpu,
      .sync_sg_for_cpu  = dma_4u_sync_sg_for_cpu,
};

const struct dma_ops *dma_ops = &sun4u_dma_ops;
EXPORT_SYMBOL(dma_ops);

int dma_supported(struct device *dev, u64 device_mask)
{
      struct iommu *iommu = dev->archdata.iommu;
      u64 dma_addr_mask = iommu->dma_addr_mask;

      if (device_mask >= (1UL << 32UL))
            return 0;

      if ((device_mask & dma_addr_mask) == dma_addr_mask)
            return 1;

#ifdef CONFIG_PCI
      if (dev->bus == &pci_bus_type)
            return pci_dma_supported(to_pci_dev(dev), device_mask);
#endif

      return 0;
}
EXPORT_SYMBOL(dma_supported);

int dma_set_mask(struct device *dev, u64 dma_mask)
{
#ifdef CONFIG_PCI
      if (dev->bus == &pci_bus_type)
            return pci_set_dma_mask(to_pci_dev(dev), dma_mask);
#endif
      return -EINVAL;
}
EXPORT_SYMBOL(dma_set_mask);

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