/* iommu.c: Generic sparc64 IOMMU support.
 *
 * Copyright (C) 1999, 2007, 2008 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>
#include <linux/iommu-helper.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 almost entirely upon the ppc64 iommu allocator.  If you use the 'handle'
 * facility it must all be done in one pass while under the iommu lock.
 *
 * On sun4u platforms, we only flush the IOMMU once every time we've passed
 * over the entire page table doing allocations.  Therefore we only ever advance
 * the hint and cannot backtrack it.
 */
unsigned long iommu_range_alloc(struct device *dev,
                                struct iommu *iommu,
                                unsigned long npages,
                                unsigned long *handle)
{
        unsigned long n, end, start, limit, boundary_size;
        struct iommu_arena *arena = &iommu->arena;
        int pass = 0;

        /* This allocator was derived from x86_64's bit string search */

        /* Sanity check */
        if (unlikely(npages == 0)) {
                if (printk_ratelimit())
                        WARN_ON(1);
                return DMA_ERROR_CODE;
        }

        if (handle && *handle)
                start = *handle;
        else
                start = arena->hint;

        limit = arena->limit;

        /* The case below can happen if we have a small segment appended
         * to a large, or when the previous alloc was at the very end of
         * the available space. If so, go back to the beginning and flush.
         */
        if (start >= limit) {
                start = 0;
                if (iommu->flush_all)
                        iommu->flush_all(iommu);
        }

 again:

        if (dev)
                boundary_size = ALIGN(dma_get_seg_boundary(dev) + 1,
                                      1 << IO_PAGE_SHIFT);
        else
                boundary_size = ALIGN(1UL << 32, 1 << IO_PAGE_SHIFT);

        n = iommu_area_alloc(arena->map, limit, start, npages,
                             iommu->page_table_map_base >> IO_PAGE_SHIFT,
                             boundary_size >> IO_PAGE_SHIFT, 0);
        if (n == -1) {
                if (likely(pass < 1)) {
                        /* First failure, rescan from the beginning.  */
                        start = 0;
                        if (iommu->flush_all)
                                iommu->flush_all(iommu);
                        pass++;
                        goto again;
                } else {
                        /* Second failure, give up */
                        return DMA_ERROR_CODE;
                }
        }

        end = n + npages;

        arena->hint = end;

        /* Update handle for SG allocations */
        if (handle)
                *handle = end;

        return n;
}

void iommu_range_free(struct iommu *iommu, dma_addr_t dma_addr, unsigned long npages)
{
        struct iommu_arena *arena = &iommu->arena;
        unsigned long entry;

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

        iommu_area_free(arena->map, entry, npages);
}

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

        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 = kmalloc_node(sz, GFP_KERNEL, numa_node);
        if (!iommu->arena.map) {
                printk(KERN_ERR "IOMMU: Error, kmalloc(arena.map) failed.\n");
                return -ENOMEM;
        }
        memset(iommu->arena.map, 0, sz);
        iommu->arena.limit = num_tsb_entries;

        if (tlb_type != hypervisor)
                iommu->flush_all = iommu_flushall;

        /* Allocate and initialize the dummy page which we
         * set inactive IO PTEs to point to.
         */
        page = alloc_pages_node(numa_node, GFP_KERNEL, 0);
        if (!page) {
                printk(KERN_ERR "IOMMU: Error, gfp(dummy_page) failed.\n");
                goto out_free_map;
        }
        iommu->dummy_page = (unsigned long) page_address(page);
        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);
        page = alloc_pages_node(numa_node, GFP_KERNEL, order);
        if (!page) {
                printk(KERN_ERR "IOMMU: Error, gfp(tsb) failed.\n");
                goto out_free_dummy_page;
        }
        iommu->page_table = (iopte_t *)page_address(page);

        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 device *dev, struct iommu *iommu,
                                    unsigned long npages)
{
        unsigned long entry;

        entry = iommu_range_alloc(dev, iommu, npages, NULL);
        if (unlikely(entry == DMA_ERROR_CODE))
                return NULL;

        return iommu->page_table + entry;
}

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)
{
        unsigned long flags, order, first_page;
        struct iommu *iommu;
        struct page *page;
        int npages, nid;
        iopte_t *iopte;
        void *ret;

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

        nid = dev->archdata.numa_node;
        page = alloc_pages_node(nid, gfp, order);
        if (unlikely(!page))
                return NULL;

        first_page = (unsigned long) page_address(page);
        memset((char *)first_page, 0, PAGE_SIZE << order);

        iommu = dev->archdata.iommu;

        spin_lock_irqsave(&iommu->lock, flags);
        iopte = alloc_npages(dev, 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);

        iommu_range_free(iommu, dvma, 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_page(struct device *dev, struct page *page,
                                  unsigned long offset, size_t sz,
                                  enum dma_data_direction direction,
                                  struct dma_attrs *attrs)
{
        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)(page_address(page) + offset);
        npages = IO_PAGE_ALIGN(oaddr + sz) - (oaddr & IO_PAGE_MASK);
        npages >>= IO_PAGE_SHIFT;

        spin_lock_irqsave(&iommu->lock, flags);
        base = alloc_npages(dev, 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[%llx] 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_page(struct device *dev, dma_addr_t bus_addr,
                              size_t sz, enum dma_data_direction direction,
                              struct dma_attrs *attrs)
{
        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);

        iommu_range_free(iommu, bus_addr, npages);

        iommu_free_ctx(iommu, ctx);

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

static int dma_4u_map_sg(struct device *dev, struct scatterlist *sglist,
                         int nelems, enum dma_data_direction direction,
                         struct dma_attrs *attrs)
{
        struct scatterlist *s, *outs, *segstart;
        unsigned long flags, handle, prot, ctx;
        dma_addr_t dma_next = 0, dma_addr;
        unsigned int max_seg_size;
        unsigned long seg_boundary_size;
        int outcount, incount, i;
        struct strbuf *strbuf;
        struct iommu *iommu;
        unsigned long base_shift;

        BUG_ON(direction == DMA_NONE);

        iommu = dev->archdata.iommu;
        strbuf = dev->archdata.stc;
        if (nelems == 0 || !iommu)
                return 0;

        spin_lock_irqsave(&iommu->lock, flags);

        ctx = 0;
        if (iommu->iommu_ctxflush)
                ctx = iommu_alloc_ctx(iommu);

        if (strbuf->strbuf_enabled)
                prot = IOPTE_STREAMING(ctx);
        else
                prot = IOPTE_CONSISTENT(ctx);
        if (direction != DMA_TO_DEVICE)
                prot |= IOPTE_WRITE;

        outs = s = segstart = &sglist[0];
        outcount = 1;
        incount = nelems;
        handle = 0;

        /* Init first segment length for backout at failure */
        outs->dma_length = 0;

        max_seg_size = dma_get_max_seg_size(dev);
        seg_boundary_size = ALIGN(dma_get_seg_boundary(dev) + 1,
                                  IO_PAGE_SIZE) >> IO_PAGE_SHIFT;
        base_shift = iommu->page_table_map_base >> IO_PAGE_SHIFT;
        for_each_sg(sglist, s, nelems, i) {
                unsigned long paddr, npages, entry, out_entry = 0, slen;
                iopte_t *base;

                slen = s->length;
                /* Sanity check */
                if (slen == 0) {
                        dma_next = 0;
                        continue;
                }
                /* Allocate iommu entries for that segment */
                paddr = (unsigned long) SG_ENT_PHYS_ADDRESS(s);
                npages = iommu_num_pages(paddr, slen, IO_PAGE_SIZE);
                entry = iommu_range_alloc(dev, iommu, npages, &handle);

                /* Handle failure */
                if (unlikely(entry == DMA_ERROR_CODE)) {
                        if (printk_ratelimit())
                                printk(KERN_INFO "iommu_alloc failed, iommu %p paddr %lx"
                                       " npages %lx\n", iommu, paddr, npages);
                        goto iommu_map_failed;
                }

                base = iommu->page_table + entry;

                /* Convert entry to a dma_addr_t */
                dma_addr = iommu->page_table_map_base +
                        (entry << IO_PAGE_SHIFT);
                dma_addr |= (s->offset & ~IO_PAGE_MASK);

                /* Insert into HW table */
                paddr &= IO_PAGE_MASK;
                while (npages--) {
                        iopte_val(*base) = prot | paddr;
                        base++;
                        paddr += IO_PAGE_SIZE;
                }

                /* If we are in an open segment, try merging */
                if (segstart != s) {
                        /* We cannot merge if:
                         * - allocated dma_addr isn't contiguous to previous allocation
                         */
                        if ((dma_addr != dma_next) ||
                            (outs->dma_length + s->length > max_seg_size) ||
                            (is_span_boundary(out_entry, base_shift,
                                              seg_boundary_size, outs, s))) {
                                /* Can't merge: create a new segment */
                                segstart = s;
                                outcount++;
                                outs = sg_next(outs);
                        } else {
                                outs->dma_length += s->length;
                        }
                }

                if (segstart == s) {
                        /* This is a new segment, fill entries */
                        outs->dma_address = dma_addr;
                        outs->dma_length = slen;
                        out_entry = entry;
                }

                /* Calculate next page pointer for contiguous check */
                dma_next = dma_addr + slen;
        }

        spin_unlock_irqrestore(&iommu->lock, flags);

        if (outcount < incount) {
                outs = sg_next(outs);
                outs->dma_address = DMA_ERROR_CODE;
                outs->dma_length = 0;
        }

        return outcount;

iommu_map_failed:
        for_each_sg(sglist, s, nelems, i) {
                if (s->dma_length != 0) {
                        unsigned long vaddr, npages, entry, j;
                        iopte_t *base;

                        vaddr = s->dma_address & IO_PAGE_MASK;
                        npages = iommu_num_pages(s->dma_address, s->dma_length,
                                                 IO_PAGE_SIZE);
                        iommu_range_free(iommu, vaddr, npages);

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

                        for (j = 0; j < npages; j++)
                                iopte_make_dummy(iommu, base + j);

                        s->dma_address = DMA_ERROR_CODE;
                        s->dma_length = 0;
                }
                if (s == outs)
                        break;
        }
        spin_unlock_irqrestore(&iommu->lock, flags);

        return 0;
}

/* If contexts are being used, they are the same in all of the mappings
 * we make for a particular SG.
 */
static unsigned long fetch_sg_ctx(struct iommu *iommu, struct scatterlist *sg)
{
        unsigned long ctx = 0;

        if (iommu->iommu_ctxflush) {
                iopte_t *base;
                u32 bus_addr;

                bus_addr = sg->dma_address & IO_PAGE_MASK;
                base = iommu->page_table +
                        ((bus_addr - iommu->page_table_map_base) >> IO_PAGE_SHIFT);

                ctx = (iopte_val(*base) & IOPTE_CONTEXT) >> 47UL;
        }
        return ctx;
}

static void dma_4u_unmap_sg(struct device *dev, struct scatterlist *sglist,
                            int nelems, enum dma_data_direction direction,
                            struct dma_attrs *attrs)
{
        unsigned long flags, ctx;
        struct scatterlist *sg;
        struct strbuf *strbuf;
        struct iommu *iommu;

        BUG_ON(direction == DMA_NONE);

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

        ctx = fetch_sg_ctx(iommu, sglist);

        spin_lock_irqsave(&iommu->lock, flags);

        sg = sglist;
        while (nelems--) {
                dma_addr_t dma_handle = sg->dma_address;
                unsigned int len = sg->dma_length;
                unsigned long npages, entry;
                iopte_t *base;
                int i;

                if (!len)
                        break;
                npages = iommu_num_pages(dma_handle, len, IO_PAGE_SIZE);
                iommu_range_free(iommu, dma_handle, npages);

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

                dma_handle &= IO_PAGE_MASK;
                if (strbuf->strbuf_enabled)
                        strbuf_flush(strbuf, iommu, dma_handle, ctx,
                                     npages, direction);

                for (i = 0; i < npages; i++)
                        iopte_make_dummy(iommu, base + i);

                sg = sg_next(sg);
        }

        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);
}

static struct dma_map_ops sun4u_dma_ops = {
        .alloc_coherent         = dma_4u_alloc_coherent,
        .free_coherent          = dma_4u_free_coherent,
        .map_page               = dma_4u_map_page,
        .unmap_page             = dma_4u_unmap_page,
        .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,
};

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

extern int pci64_dma_supported(struct pci_dev *pdev, u64 device_mask);

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 pci64_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);