ARM: dma-api: fix max_pfn off-by-one error in __dma_supported()

[linux/fpc-iii.git] / arch / ia64 / hp / common / sba_iommu.c

// SPDX-License-Identifier: GPL-2.0-or-later
/*
**  IA64 System Bus Adapter (SBA) I/O MMU manager
**
**      (c) Copyright 2002-2005 Alex Williamson
**      (c) Copyright 2002-2003 Grant Grundler
**      (c) Copyright 2002-2005 Hewlett-Packard Company
**
**      Portions (c) 2000 Grant Grundler (from parisc I/O MMU code)
**      Portions (c) 1999 Dave S. Miller (from sparc64 I/O MMU code)
**
**
**
** This module initializes the IOC (I/O Controller) found on HP
** McKinley machines and their successors.
**
*/

#include <linux/types.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/spinlock.h>
#include <linux/slab.h>
#include <linux/init.h>
#include <linux/mm.h>
#include <linux/string.h>
#include <linux/pci.h>
#include <linux/proc_fs.h>
#include <linux/seq_file.h>
#include <linux/acpi.h>
#include <linux/efi.h>
#include <linux/nodemask.h>
#include <linux/bitops.h>         /* hweight64() */
#include <linux/crash_dump.h>
#include <linux/iommu-helper.h>
#include <linux/dma-mapping.h>
#include <linux/prefetch.h>
#include <linux/swiotlb.h>

#include <asm/delay.h>          /* ia64_get_itc() */
#include <asm/io.h>
#include <asm/page.h>           /* PAGE_OFFSET */
#include <asm/dma.h>

#include <asm/acpi-ext.h>

#define PFX "IOC: "

/*
** Enabling timing search of the pdir resource map.  Output in /proc.
** Disabled by default to optimize performance.
*/
#undef PDIR_SEARCH_TIMING

/*
** This option allows cards capable of 64bit DMA to bypass the IOMMU.  If
** not defined, all DMA will be 32bit and go through the TLB.
** There's potentially a conflict in the bio merge code with us
** advertising an iommu, but then bypassing it.  Since I/O MMU bypassing
** appears to give more performance than bio-level virtual merging, we'll
** do the former for now.  NOTE: BYPASS_SG also needs to be undef'd to
** completely restrict DMA to the IOMMU.
*/
#define ALLOW_IOV_BYPASS

/*
** This option specifically allows/disallows bypassing scatterlists with
** multiple entries.  Coalescing these entries can allow better DMA streaming
** and in some cases shows better performance than entirely bypassing the
** IOMMU.  Performance increase on the order of 1-2% sequential output/input
** using bonnie++ on a RAID0 MD device (sym2 & mpt).
*/
#undef ALLOW_IOV_BYPASS_SG

/*
** If a device prefetches beyond the end of a valid pdir entry, it will cause
** a hard failure, ie. MCA.  Version 3.0 and later of the zx1 LBA should
** disconnect on 4k boundaries and prevent such issues.  If the device is
** particularly aggressive, this option will keep the entire pdir valid such
** that prefetching will hit a valid address.  This could severely impact
** error containment, and is therefore off by default.  The page that is
** used for spill-over is poisoned, so that should help debugging somewhat.
*/
#undef FULL_VALID_PDIR

#define ENABLE_MARK_CLEAN

/*
** The number of debug flags is a clue - this code is fragile.  NOTE: since
** tightening the use of res_lock the resource bitmap and actual pdir are no
** longer guaranteed to stay in sync.  The sanity checking code isn't going to
** like that.
*/
#undef DEBUG_SBA_INIT
#undef DEBUG_SBA_RUN
#undef DEBUG_SBA_RUN_SG
#undef DEBUG_SBA_RESOURCE
#undef ASSERT_PDIR_SANITY
#undef DEBUG_LARGE_SG_ENTRIES
#undef DEBUG_BYPASS

#if defined(FULL_VALID_PDIR) && defined(ASSERT_PDIR_SANITY)
#error FULL_VALID_PDIR and ASSERT_PDIR_SANITY are mutually exclusive
#endif

#define SBA_INLINE      __inline__
/* #define SBA_INLINE */

#ifdef DEBUG_SBA_INIT
#define DBG_INIT(x...)  printk(x)
#else
#define DBG_INIT(x...)
#endif

#ifdef DEBUG_SBA_RUN
#define DBG_RUN(x...)   printk(x)
#else
#define DBG_RUN(x...)
#endif

#ifdef DEBUG_SBA_RUN_SG
#define DBG_RUN_SG(x...)        printk(x)
#else
#define DBG_RUN_SG(x...)
#endif


#ifdef DEBUG_SBA_RESOURCE
#define DBG_RES(x...)   printk(x)
#else
#define DBG_RES(x...)
#endif

#ifdef DEBUG_BYPASS
#define DBG_BYPASS(x...)        printk(x)
#else
#define DBG_BYPASS(x...)
#endif

#ifdef ASSERT_PDIR_SANITY
#define ASSERT(expr) \
        if(!(expr)) { \
                printk( "\n" __FILE__ ":%d: Assertion " #expr " failed!\n",__LINE__); \
                panic(#expr); \
        }
#else
#define ASSERT(expr)
#endif

/*
** The number of pdir entries to "free" before issuing
** a read to PCOM register to flush out PCOM writes.
** Interacts with allocation granularity (ie 4 or 8 entries
** allocated and free'd/purged at a time might make this
** less interesting).
*/
#define DELAYED_RESOURCE_CNT    64

#define PCI_DEVICE_ID_HP_SX2000_IOC     0x12ec

#define ZX1_IOC_ID      ((PCI_DEVICE_ID_HP_ZX1_IOC << 16) | PCI_VENDOR_ID_HP)
#define ZX2_IOC_ID      ((PCI_DEVICE_ID_HP_ZX2_IOC << 16) | PCI_VENDOR_ID_HP)
#define REO_IOC_ID      ((PCI_DEVICE_ID_HP_REO_IOC << 16) | PCI_VENDOR_ID_HP)
#define SX1000_IOC_ID   ((PCI_DEVICE_ID_HP_SX1000_IOC << 16) | PCI_VENDOR_ID_HP)
#define SX2000_IOC_ID   ((PCI_DEVICE_ID_HP_SX2000_IOC << 16) | PCI_VENDOR_ID_HP)

#define ZX1_IOC_OFFSET  0x1000  /* ACPI reports SBA, we want IOC */

#define IOC_FUNC_ID     0x000
#define IOC_FCLASS      0x008   /* function class, bist, header, rev... */
#define IOC_IBASE       0x300   /* IO TLB */
#define IOC_IMASK       0x308
#define IOC_PCOM        0x310
#define IOC_TCNFG       0x318
#define IOC_PDIR_BASE   0x320

#define IOC_ROPE0_CFG   0x500
#define   IOC_ROPE_AO     0x10  /* Allow "Relaxed Ordering" */


/* AGP GART driver looks for this */
#define ZX1_SBA_IOMMU_COOKIE    0x0000badbadc0ffeeUL

/*
** The zx1 IOC supports 4/8/16/64KB page sizes (see TCNFG register)
**
** Some IOCs (sx1000) can run at the above pages sizes, but are
** really only supported using the IOC at a 4k page size.
**
** iovp_size could only be greater than PAGE_SIZE if we are
** confident the drivers really only touch the next physical
** page iff that driver instance owns it.
*/
static unsigned long iovp_size;
static unsigned long iovp_shift;
static unsigned long iovp_mask;

struct ioc {
        void __iomem    *ioc_hpa;       /* I/O MMU base address */
        char            *res_map;       /* resource map, bit == pdir entry */
        u64             *pdir_base;     /* physical base address */
        unsigned long   ibase;          /* pdir IOV Space base */
        unsigned long   imask;          /* pdir IOV Space mask */

        unsigned long   *res_hint;      /* next avail IOVP - circular search */
        unsigned long   dma_mask;
        spinlock_t      res_lock;       /* protects the resource bitmap, but must be held when */
                                        /* clearing pdir to prevent races with allocations. */
        unsigned int    res_bitshift;   /* from the RIGHT! */
        unsigned int    res_size;       /* size of resource map in bytes */
#ifdef CONFIG_NUMA
        unsigned int    node;           /* node where this IOC lives */
#endif
#if DELAYED_RESOURCE_CNT > 0
        spinlock_t      saved_lock;     /* may want to try to get this on a separate cacheline */
                                        /* than res_lock for bigger systems. */
        int             saved_cnt;
        struct sba_dma_pair {
                dma_addr_t      iova;
                size_t          size;
        } saved[DELAYED_RESOURCE_CNT];
#endif

#ifdef PDIR_SEARCH_TIMING
#define SBA_SEARCH_SAMPLE       0x100
        unsigned long avg_search[SBA_SEARCH_SAMPLE];
        unsigned long avg_idx;  /* current index into avg_search */
#endif

        /* Stuff we don't need in performance path */
        struct ioc      *next;          /* list of IOC's in system */
        acpi_handle     handle;         /* for multiple IOC's */
        const char      *name;
        unsigned int    func_id;
        unsigned int    rev;            /* HW revision of chip */
        u32             iov_size;
        unsigned int    pdir_size;      /* in bytes, determined by IOV Space size */
        struct pci_dev  *sac_only_dev;
};

static struct ioc *ioc_list, *ioc_found;
static int reserve_sba_gart = 1;

static SBA_INLINE void sba_mark_invalid(struct ioc *, dma_addr_t, size_t);
static SBA_INLINE void sba_free_range(struct ioc *, dma_addr_t, size_t);

#define sba_sg_address(sg)      sg_virt((sg))

#ifdef FULL_VALID_PDIR
static u64 prefetch_spill_page;
#endif

#define GET_IOC(dev)    ((dev_is_pci(dev))                                              \
                         ? ((struct ioc *) PCI_CONTROLLER(to_pci_dev(dev))->iommu) : NULL)

/*
** DMA_CHUNK_SIZE is used by the SCSI mid-layer to break up
** (or rather not merge) DMAs into manageable chunks.
** On parisc, this is more of the software/tuning constraint
** rather than the HW. I/O MMU allocation algorithms can be
** faster with smaller sizes (to some degree).
*/
#define DMA_CHUNK_SIZE  (BITS_PER_LONG*iovp_size)

#define ROUNDUP(x,y) ((x + ((y)-1)) & ~((y)-1))

/************************************
** SBA register read and write support
**
** BE WARNED: register writes are posted.
**  (ie follow writes which must reach HW with a read)
**
*/
#define READ_REG(addr)       __raw_readq(addr)
#define WRITE_REG(val, addr) __raw_writeq(val, addr)

#ifdef DEBUG_SBA_INIT

/**
 * sba_dump_tlb - debugging only - print IOMMU operating parameters
 * @hpa: base address of the IOMMU
 *
 * Print the size/location of the IO MMU PDIR.
 */
static void
sba_dump_tlb(char *hpa)
{
        DBG_INIT("IO TLB at 0x%p\n", (void *)hpa);
        DBG_INIT("IOC_IBASE    : %016lx\n", READ_REG(hpa+IOC_IBASE));
        DBG_INIT("IOC_IMASK    : %016lx\n", READ_REG(hpa+IOC_IMASK));
        DBG_INIT("IOC_TCNFG    : %016lx\n", READ_REG(hpa+IOC_TCNFG));
        DBG_INIT("IOC_PDIR_BASE: %016lx\n", READ_REG(hpa+IOC_PDIR_BASE));
        DBG_INIT("\n");
}
#endif


#ifdef ASSERT_PDIR_SANITY

/**
 * sba_dump_pdir_entry - debugging only - print one IOMMU PDIR entry
 * @ioc: IO MMU structure which owns the pdir we are interested in.
 * @msg: text to print ont the output line.
 * @pide: pdir index.
 *
 * Print one entry of the IO MMU PDIR in human readable form.
 */
static void
sba_dump_pdir_entry(struct ioc *ioc, char *msg, uint pide)
{
        /* start printing from lowest pde in rval */
        u64 *ptr = &ioc->pdir_base[pide  & ~(BITS_PER_LONG - 1)];
        unsigned long *rptr = (unsigned long *) &ioc->res_map[(pide >>3) & -sizeof(unsigned long)];
        uint rcnt;

        printk(KERN_DEBUG "SBA: %s rp %p bit %d rval 0x%lx\n",
                 msg, rptr, pide & (BITS_PER_LONG - 1), *rptr);

        rcnt = 0;
        while (rcnt < BITS_PER_LONG) {
                printk(KERN_DEBUG "%s %2d %p %016Lx\n",
                       (rcnt == (pide & (BITS_PER_LONG - 1)))
                       ? "    -->" : "       ",
                       rcnt, ptr, (unsigned long long) *ptr );
                rcnt++;
                ptr++;
        }
        printk(KERN_DEBUG "%s", msg);
}


/**
 * sba_check_pdir - debugging only - consistency checker
 * @ioc: IO MMU structure which owns the pdir we are interested in.
 * @msg: text to print ont the output line.
 *
 * Verify the resource map and pdir state is consistent
 */
static int
sba_check_pdir(struct ioc *ioc, char *msg)
{
        u64 *rptr_end = (u64 *) &(ioc->res_map[ioc->res_size]);
        u64 *rptr = (u64 *) ioc->res_map;       /* resource map ptr */
        u64 *pptr = ioc->pdir_base;     /* pdir ptr */
        uint pide = 0;

        while (rptr < rptr_end) {
                u64 rval;
                int rcnt; /* number of bits we might check */

                rval = *rptr;
                rcnt = 64;

                while (rcnt) {
                        /* Get last byte and highest bit from that */
                        u32 pde = ((u32)((*pptr >> (63)) & 0x1));
                        if ((rval & 0x1) ^ pde)
                        {
                                /*
                                ** BUMMER!  -- res_map != pdir --
                                ** Dump rval and matching pdir entries
                                */
                                sba_dump_pdir_entry(ioc, msg, pide);
                                return(1);
                        }
                        rcnt--;
                        rval >>= 1;     /* try the next bit */
                        pptr++;
                        pide++;
                }
                rptr++; /* look at next word of res_map */
        }
        /* It'd be nice if we always got here :^) */
        return 0;
}


/**
 * sba_dump_sg - debugging only - print Scatter-Gather list
 * @ioc: IO MMU structure which owns the pdir we are interested in.
 * @startsg: head of the SG list
 * @nents: number of entries in SG list
 *
 * print the SG list so we can verify it's correct by hand.
 */
static void
sba_dump_sg( struct ioc *ioc, struct scatterlist *startsg, int nents)
{
        while (nents-- > 0) {
                printk(KERN_DEBUG " %d : DMA %08lx/%05x CPU %p\n", nents,
                       startsg->dma_address, startsg->dma_length,
                       sba_sg_address(startsg));
                startsg = sg_next(startsg);
        }
}

static void
sba_check_sg( struct ioc *ioc, struct scatterlist *startsg, int nents)
{
        struct scatterlist *the_sg = startsg;
        int the_nents = nents;

        while (the_nents-- > 0) {
                if (sba_sg_address(the_sg) == 0x0UL)
                        sba_dump_sg(NULL, startsg, nents);
                the_sg = sg_next(the_sg);
        }
}

#endif /* ASSERT_PDIR_SANITY */




/**************************************************************
*
*   I/O Pdir Resource Management
*
*   Bits set in the resource map are in use.
*   Each bit can represent a number of pages.
*   LSbs represent lower addresses (IOVA's).
*
***************************************************************/
#define PAGES_PER_RANGE 1       /* could increase this to 4 or 8 if needed */

/* Convert from IOVP to IOVA and vice versa. */
#define SBA_IOVA(ioc,iovp,offset) ((ioc->ibase) | (iovp) | (offset))
#define SBA_IOVP(ioc,iova) ((iova) & ~(ioc->ibase))

#define PDIR_ENTRY_SIZE sizeof(u64)

#define PDIR_INDEX(iovp)   ((iovp)>>iovp_shift)

#define RESMAP_MASK(n)    ~(~0UL << (n))
#define RESMAP_IDX_MASK   (sizeof(unsigned long) - 1)


/**
 * For most cases the normal get_order is sufficient, however it limits us
 * to PAGE_SIZE being the minimum mapping alignment and TC flush granularity.
 * It only incurs about 1 clock cycle to use this one with the static variable
 * and makes the code more intuitive.
 */
static SBA_INLINE int
get_iovp_order (unsigned long size)
{
        long double d = size - 1;
        long order;

        order = ia64_getf_exp(d);
        order = order - iovp_shift - 0xffff + 1;
        if (order < 0)
                order = 0;
        return order;
}

static unsigned long ptr_to_pide(struct ioc *ioc, unsigned long *res_ptr,
                                 unsigned int bitshiftcnt)
{
        return (((unsigned long)res_ptr - (unsigned long)ioc->res_map) << 3)
                + bitshiftcnt;
}

/**
 * sba_search_bitmap - find free space in IO PDIR resource bitmap
 * @ioc: IO MMU structure which owns the pdir we are interested in.
 * @bits_wanted: number of entries we need.
 * @use_hint: use res_hint to indicate where to start looking
 *
 * Find consecutive free bits in resource bitmap.
 * Each bit represents one entry in the IO Pdir.
 * Cool perf optimization: search for log2(size) bits at a time.
 */
static SBA_INLINE unsigned long
sba_search_bitmap(struct ioc *ioc, struct device *dev,
                  unsigned long bits_wanted, int use_hint)
{
        unsigned long *res_ptr;
        unsigned long *res_end = (unsigned long *) &(ioc->res_map[ioc->res_size]);
        unsigned long flags, pide = ~0UL, tpide;
        unsigned long boundary_size;
        unsigned long shift;
        int ret;

        ASSERT(((unsigned long) ioc->res_hint & (sizeof(unsigned long) - 1UL)) == 0);
        ASSERT(res_ptr < res_end);

        boundary_size = (unsigned long long)dma_get_seg_boundary(dev) + 1;
        boundary_size = ALIGN(boundary_size, 1ULL << iovp_shift) >> iovp_shift;

        BUG_ON(ioc->ibase & ~iovp_mask);
        shift = ioc->ibase >> iovp_shift;

        spin_lock_irqsave(&ioc->res_lock, flags);

        /* Allow caller to force a search through the entire resource space */
        if (likely(use_hint)) {
                res_ptr = ioc->res_hint;
        } else {
                res_ptr = (ulong *)ioc->res_map;
                ioc->res_bitshift = 0;
        }

        /*
         * N.B.  REO/Grande defect AR2305 can cause TLB fetch timeouts
         * if a TLB entry is purged while in use.  sba_mark_invalid()
         * purges IOTLB entries in power-of-two sizes, so we also
         * allocate IOVA space in power-of-two sizes.
         */
        bits_wanted = 1UL << get_iovp_order(bits_wanted << iovp_shift);

        if (likely(bits_wanted == 1)) {
                unsigned int bitshiftcnt;
                for(; res_ptr < res_end ; res_ptr++) {
                        if (likely(*res_ptr != ~0UL)) {
                                bitshiftcnt = ffz(*res_ptr);
                                *res_ptr |= (1UL << bitshiftcnt);
                                pide = ptr_to_pide(ioc, res_ptr, bitshiftcnt);
                                ioc->res_bitshift = bitshiftcnt + bits_wanted;
                                goto found_it;
                        }
                }
                goto not_found;

        }
        
        if (likely(bits_wanted <= BITS_PER_LONG/2)) {
                /*
                ** Search the resource bit map on well-aligned values.
                ** "o" is the alignment.
                ** We need the alignment to invalidate I/O TLB using
                ** SBA HW features in the unmap path.
                */
                unsigned long o = 1 << get_iovp_order(bits_wanted << iovp_shift);
                uint bitshiftcnt = ROUNDUP(ioc->res_bitshift, o);
                unsigned long mask, base_mask;

                base_mask = RESMAP_MASK(bits_wanted);
                mask = base_mask << bitshiftcnt;

                DBG_RES("%s() o %ld %p", __func__, o, res_ptr);
                for(; res_ptr < res_end ; res_ptr++)
                { 
                        DBG_RES("    %p %lx %lx\n", res_ptr, mask, *res_ptr);
                        ASSERT(0 != mask);
                        for (; mask ; mask <<= o, bitshiftcnt += o) {
                                tpide = ptr_to_pide(ioc, res_ptr, bitshiftcnt);
                                ret = iommu_is_span_boundary(tpide, bits_wanted,
                                                             shift,
                                                             boundary_size);
                                if ((0 == ((*res_ptr) & mask)) && !ret) {
                                        *res_ptr |= mask;     /* mark resources busy! */
                                        pide = tpide;
                                        ioc->res_bitshift = bitshiftcnt + bits_wanted;
                                        goto found_it;
                                }
                        }

                        bitshiftcnt = 0;
                        mask = base_mask;

                }

        } else {
                int qwords, bits, i;
                unsigned long *end;

                qwords = bits_wanted >> 6; /* /64 */
                bits = bits_wanted - (qwords * BITS_PER_LONG);

                end = res_end - qwords;

                for (; res_ptr < end; res_ptr++) {
                        tpide = ptr_to_pide(ioc, res_ptr, 0);
                        ret = iommu_is_span_boundary(tpide, bits_wanted,
                                                     shift, boundary_size);
                        if (ret)
                                goto next_ptr;
                        for (i = 0 ; i < qwords ; i++) {
                                if (res_ptr[i] != 0)
                                        goto next_ptr;
                        }
                        if (bits && res_ptr[i] && (__ffs(res_ptr[i]) < bits))
                                continue;

                        /* Found it, mark it */
                        for (i = 0 ; i < qwords ; i++)
                                res_ptr[i] = ~0UL;
                        res_ptr[i] |= RESMAP_MASK(bits);

                        pide = tpide;
                        res_ptr += qwords;
                        ioc->res_bitshift = bits;
                        goto found_it;
next_ptr:
                        ;
                }
        }

not_found:
        prefetch(ioc->res_map);
        ioc->res_hint = (unsigned long *) ioc->res_map;
        ioc->res_bitshift = 0;
        spin_unlock_irqrestore(&ioc->res_lock, flags);
        return (pide);

found_it:
        ioc->res_hint = res_ptr;
        spin_unlock_irqrestore(&ioc->res_lock, flags);
        return (pide);
}


/**
 * sba_alloc_range - find free bits and mark them in IO PDIR resource bitmap
 * @ioc: IO MMU structure which owns the pdir we are interested in.
 * @size: number of bytes to create a mapping for
 *
 * Given a size, find consecutive unmarked and then mark those bits in the
 * resource bit map.
 */
static int
sba_alloc_range(struct ioc *ioc, struct device *dev, size_t size)
{
        unsigned int pages_needed = size >> iovp_shift;
#ifdef PDIR_SEARCH_TIMING
        unsigned long itc_start;
#endif
        unsigned long pide;

        ASSERT(pages_needed);
        ASSERT(0 == (size & ~iovp_mask));

#ifdef PDIR_SEARCH_TIMING
        itc_start = ia64_get_itc();
#endif
        /*
        ** "seek and ye shall find"...praying never hurts either...
        */
        pide = sba_search_bitmap(ioc, dev, pages_needed, 1);
        if (unlikely(pide >= (ioc->res_size << 3))) {
                pide = sba_search_bitmap(ioc, dev, pages_needed, 0);
                if (unlikely(pide >= (ioc->res_size << 3))) {
#if DELAYED_RESOURCE_CNT > 0
                        unsigned long flags;

                        /*
                        ** With delayed resource freeing, we can give this one more shot.  We're
                        ** getting close to being in trouble here, so do what we can to make this
                        ** one count.
                        */
                        spin_lock_irqsave(&ioc->saved_lock, flags);
                        if (ioc->saved_cnt > 0) {
                                struct sba_dma_pair *d;
                                int cnt = ioc->saved_cnt;

                                d = &(ioc->saved[ioc->saved_cnt - 1]);

                                spin_lock(&ioc->res_lock);
                                while (cnt--) {
                                        sba_mark_invalid(ioc, d->iova, d->size);
                                        sba_free_range(ioc, d->iova, d->size);
                                        d--;
                                }
                                ioc->saved_cnt = 0;
                                READ_REG(ioc->ioc_hpa+IOC_PCOM);        /* flush purges */
                                spin_unlock(&ioc->res_lock);
                        }
                        spin_unlock_irqrestore(&ioc->saved_lock, flags);

                        pide = sba_search_bitmap(ioc, dev, pages_needed, 0);
                        if (unlikely(pide >= (ioc->res_size << 3))) {
                                printk(KERN_WARNING "%s: I/O MMU @ %p is"
                                       "out of mapping resources, %u %u %lx\n",
                                       __func__, ioc->ioc_hpa, ioc->res_size,
                                       pages_needed, dma_get_seg_boundary(dev));
                                return -1;
                        }
#else
                        printk(KERN_WARNING "%s: I/O MMU @ %p is"
                               "out of mapping resources, %u %u %lx\n",
                               __func__, ioc->ioc_hpa, ioc->res_size,
                               pages_needed, dma_get_seg_boundary(dev));
                        return -1;
#endif
                }
        }

#ifdef PDIR_SEARCH_TIMING
        ioc->avg_search[ioc->avg_idx++] = (ia64_get_itc() - itc_start) / pages_needed;
        ioc->avg_idx &= SBA_SEARCH_SAMPLE - 1;
#endif

        prefetchw(&(ioc->pdir_base[pide]));

#ifdef ASSERT_PDIR_SANITY
        /* verify the first enable bit is clear */
        if(0x00 != ((u8 *) ioc->pdir_base)[pide*PDIR_ENTRY_SIZE + 7]) {
                sba_dump_pdir_entry(ioc, "sba_search_bitmap() botched it?", pide);
        }
#endif

        DBG_RES("%s(%x) %d -> %lx hint %x/%x\n",
                __func__, size, pages_needed, pide,
                (uint) ((unsigned long) ioc->res_hint - (unsigned long) ioc->res_map),
                ioc->res_bitshift );

        return (pide);
}


/**
 * sba_free_range - unmark bits in IO PDIR resource bitmap
 * @ioc: IO MMU structure which owns the pdir we are interested in.
 * @iova: IO virtual address which was previously allocated.
 * @size: number of bytes to create a mapping for
 *
 * clear bits in the ioc's resource map
 */
static SBA_INLINE void
sba_free_range(struct ioc *ioc, dma_addr_t iova, size_t size)
{
        unsigned long iovp = SBA_IOVP(ioc, iova);
        unsigned int pide = PDIR_INDEX(iovp);
        unsigned int ridx = pide >> 3;  /* convert bit to byte address */
        unsigned long *res_ptr = (unsigned long *) &((ioc)->res_map[ridx & ~RESMAP_IDX_MASK]);
        int bits_not_wanted = size >> iovp_shift;
        unsigned long m;

        /* Round up to power-of-two size: see AR2305 note above */
        bits_not_wanted = 1UL << get_iovp_order(bits_not_wanted << iovp_shift);
        for (; bits_not_wanted > 0 ; res_ptr++) {
                
                if (unlikely(bits_not_wanted > BITS_PER_LONG)) {

                        /* these mappings start 64bit aligned */
                        *res_ptr = 0UL;
                        bits_not_wanted -= BITS_PER_LONG;
                        pide += BITS_PER_LONG;

                } else {

                        /* 3-bits "bit" address plus 2 (or 3) bits for "byte" == bit in word */
                        m = RESMAP_MASK(bits_not_wanted) << (pide & (BITS_PER_LONG - 1));
                        bits_not_wanted = 0;

                        DBG_RES("%s( ,%x,%x) %x/%lx %x %p %lx\n", __func__, (uint) iova, size,
                                bits_not_wanted, m, pide, res_ptr, *res_ptr);

                        ASSERT(m != 0);
                        ASSERT(bits_not_wanted);
                        ASSERT((*res_ptr & m) == m); /* verify same bits are set */
                        *res_ptr &= ~m;
                }
        }
}


/**************************************************************
*
*   "Dynamic DMA Mapping" support (aka "Coherent I/O")
*
***************************************************************/

/**
 * sba_io_pdir_entry - fill in one IO PDIR entry
 * @pdir_ptr:  pointer to IO PDIR entry
 * @vba: Virtual CPU address of buffer to map
 *
 * SBA Mapping Routine
 *
 * Given a virtual address (vba, arg1) sba_io_pdir_entry()
 * loads the I/O PDIR entry pointed to by pdir_ptr (arg0).
 * Each IO Pdir entry consists of 8 bytes as shown below
 * (LSB == bit 0):
 *
 *  63                    40                                 11    7        0
 * +-+---------------------+----------------------------------+----+--------+
 * |V|        U            |            PPN[39:12]            | U  |   FF   |
 * +-+---------------------+----------------------------------+----+--------+
 *
 *  V  == Valid Bit
 *  U  == Unused
 * PPN == Physical Page Number
 *
 * The physical address fields are filled with the results of virt_to_phys()
 * on the vba.
 */

#if 1
#define sba_io_pdir_entry(pdir_ptr, vba) *pdir_ptr = ((vba & ~0xE000000000000FFFULL)    \
                                                      | 0x8000000000000000ULL)
#else
void SBA_INLINE
sba_io_pdir_entry(u64 *pdir_ptr, unsigned long vba)
{
        *pdir_ptr = ((vba & ~0xE000000000000FFFULL) | 0x80000000000000FFULL);
}
#endif

#ifdef ENABLE_MARK_CLEAN
/**
 * Since DMA is i-cache coherent, any (complete) pages that were written via
 * DMA can be marked as "clean" so that lazy_mmu_prot_update() doesn't have to
 * flush them when they get mapped into an executable vm-area.
 */
static void
mark_clean (void *addr, size_t size)
{
        unsigned long pg_addr, end;

        pg_addr = PAGE_ALIGN((unsigned long) addr);
        end = (unsigned long) addr + size;
        while (pg_addr + PAGE_SIZE <= end) {
                struct page *page = virt_to_page((void *)pg_addr);
                set_bit(PG_arch_1, &page->flags);
                pg_addr += PAGE_SIZE;
        }
}
#endif

/**
 * sba_mark_invalid - invalidate one or more IO PDIR entries
 * @ioc: IO MMU structure which owns the pdir we are interested in.
 * @iova:  IO Virtual Address mapped earlier
 * @byte_cnt:  number of bytes this mapping covers.
 *
 * Marking the IO PDIR entry(ies) as Invalid and invalidate
 * corresponding IO TLB entry. The PCOM (Purge Command Register)
 * is to purge stale entries in the IO TLB when unmapping entries.
 *
 * The PCOM register supports purging of multiple pages, with a minium
 * of 1 page and a maximum of 2GB. Hardware requires the address be
 * aligned to the size of the range being purged. The size of the range
 * must be a power of 2. The "Cool perf optimization" in the
 * allocation routine helps keep that true.
 */
static SBA_INLINE void
sba_mark_invalid(struct ioc *ioc, dma_addr_t iova, size_t byte_cnt)
{
        u32 iovp = (u32) SBA_IOVP(ioc,iova);

        int off = PDIR_INDEX(iovp);

        /* Must be non-zero and rounded up */
        ASSERT(byte_cnt > 0);
        ASSERT(0 == (byte_cnt & ~iovp_mask));

#ifdef ASSERT_PDIR_SANITY
        /* Assert first pdir entry is set */
        if (!(ioc->pdir_base[off] >> 60)) {
                sba_dump_pdir_entry(ioc,"sba_mark_invalid()", PDIR_INDEX(iovp));
        }
#endif

        if (byte_cnt <= iovp_size)
        {
                ASSERT(off < ioc->pdir_size);

                iovp |= iovp_shift;     /* set "size" field for PCOM */

#ifndef FULL_VALID_PDIR
                /*
                ** clear I/O PDIR entry "valid" bit
                ** Do NOT clear the rest - save it for debugging.
                ** We should only clear bits that have previously
                ** been enabled.
                */
                ioc->pdir_base[off] &= ~(0x80000000000000FFULL);
#else
                /*
                ** If we want to maintain the PDIR as valid, put in
                ** the spill page so devices prefetching won't
                ** cause a hard fail.
                */
                ioc->pdir_base[off] = (0x80000000000000FFULL | prefetch_spill_page);
#endif
        } else {
                u32 t = get_iovp_order(byte_cnt) + iovp_shift;

                iovp |= t;
                ASSERT(t <= 31);   /* 2GB! Max value of "size" field */

                do {
                        /* verify this pdir entry is enabled */
                        ASSERT(ioc->pdir_base[off]  >> 63);
#ifndef FULL_VALID_PDIR
                        /* clear I/O Pdir entry "valid" bit first */
                        ioc->pdir_base[off] &= ~(0x80000000000000FFULL);
#else
                        ioc->pdir_base[off] = (0x80000000000000FFULL | prefetch_spill_page);
#endif
                        off++;
                        byte_cnt -= iovp_size;
                } while (byte_cnt > 0);
        }

        WRITE_REG(iovp | ioc->ibase, ioc->ioc_hpa+IOC_PCOM);
}

/**
 * sba_map_page - map one buffer and return IOVA for DMA
 * @dev: instance of PCI owned by the driver that's asking.
 * @page: page to map
 * @poff: offset into page
 * @size: number of bytes to map
 * @dir: dma direction
 * @attrs: optional dma attributes
 *
 * See Documentation/DMA-API-HOWTO.txt
 */
static dma_addr_t sba_map_page(struct device *dev, struct page *page,
                               unsigned long poff, size_t size,
                               enum dma_data_direction dir,
                               unsigned long attrs)
{
        struct ioc *ioc;
        void *addr = page_address(page) + poff;
        dma_addr_t iovp;
        dma_addr_t offset;
        u64 *pdir_start;
        int pide;
#ifdef ASSERT_PDIR_SANITY
        unsigned long flags;
#endif
#ifdef ALLOW_IOV_BYPASS
        unsigned long pci_addr = virt_to_phys(addr);
#endif

#ifdef ALLOW_IOV_BYPASS
        ASSERT(to_pci_dev(dev)->dma_mask);
        /*
        ** Check if the PCI device can DMA to ptr... if so, just return ptr
        */
        if (likely((pci_addr & ~to_pci_dev(dev)->dma_mask) == 0)) {
                /*
                ** Device is bit capable of DMA'ing to the buffer...
                ** just return the PCI address of ptr
                */
                DBG_BYPASS("sba_map_page() bypass mask/addr: "
                           "0x%lx/0x%lx\n",
                           to_pci_dev(dev)->dma_mask, pci_addr);
                return pci_addr;
        }
#endif
        ioc = GET_IOC(dev);
        ASSERT(ioc);

        prefetch(ioc->res_hint);

        ASSERT(size > 0);
        ASSERT(size <= DMA_CHUNK_SIZE);

        /* save offset bits */
        offset = ((dma_addr_t) (long) addr) & ~iovp_mask;

        /* round up to nearest iovp_size */
        size = (size + offset + ~iovp_mask) & iovp_mask;

#ifdef ASSERT_PDIR_SANITY
        spin_lock_irqsave(&ioc->res_lock, flags);
        if (sba_check_pdir(ioc,"Check before sba_map_page()"))
                panic("Sanity check failed");
        spin_unlock_irqrestore(&ioc->res_lock, flags);
#endif

        pide = sba_alloc_range(ioc, dev, size);
        if (pide < 0)
                return DMA_MAPPING_ERROR;

        iovp = (dma_addr_t) pide << iovp_shift;

        DBG_RUN("%s() 0x%p -> 0x%lx\n", __func__, addr, (long) iovp | offset);

        pdir_start = &(ioc->pdir_base[pide]);

        while (size > 0) {
                ASSERT(((u8 *)pdir_start)[7] == 0); /* verify availability */
                sba_io_pdir_entry(pdir_start, (unsigned long) addr);

                DBG_RUN("     pdir 0x%p %lx\n", pdir_start, *pdir_start);

                addr += iovp_size;
                size -= iovp_size;
                pdir_start++;
        }
        /* force pdir update */
        wmb();

        /* form complete address */
#ifdef ASSERT_PDIR_SANITY
        spin_lock_irqsave(&ioc->res_lock, flags);
        sba_check_pdir(ioc,"Check after sba_map_page()");
        spin_unlock_irqrestore(&ioc->res_lock, flags);
#endif
        return SBA_IOVA(ioc, iovp, offset);
}

#ifdef ENABLE_MARK_CLEAN
static SBA_INLINE void
sba_mark_clean(struct ioc *ioc, dma_addr_t iova, size_t size)
{
        u32     iovp = (u32) SBA_IOVP(ioc,iova);
        int     off = PDIR_INDEX(iovp);
        void    *addr;

        if (size <= iovp_size) {
                addr = phys_to_virt(ioc->pdir_base[off] &
                                    ~0xE000000000000FFFULL);
                mark_clean(addr, size);
        } else {
                do {
                        addr = phys_to_virt(ioc->pdir_base[off] &
                                            ~0xE000000000000FFFULL);
                        mark_clean(addr, min(size, iovp_size));
                        off++;
                        size -= iovp_size;
                } while (size > 0);
        }
}
#endif

/**
 * sba_unmap_page - unmap one IOVA and free resources
 * @dev: instance of PCI owned by the driver that's asking.
 * @iova:  IOVA of driver buffer previously mapped.
 * @size:  number of bytes mapped in driver buffer.
 * @dir:  R/W or both.
 * @attrs: optional dma attributes
 *
 * See Documentation/DMA-API-HOWTO.txt
 */
static void sba_unmap_page(struct device *dev, dma_addr_t iova, size_t size,
                           enum dma_data_direction dir, unsigned long attrs)
{
        struct ioc *ioc;
#if DELAYED_RESOURCE_CNT > 0
        struct sba_dma_pair *d;
#endif
        unsigned long flags;
        dma_addr_t offset;

        ioc = GET_IOC(dev);
        ASSERT(ioc);

#ifdef ALLOW_IOV_BYPASS
        if (likely((iova & ioc->imask) != ioc->ibase)) {
                /*
                ** Address does not fall w/in IOVA, must be bypassing
                */
                DBG_BYPASS("sba_unmap_page() bypass addr: 0x%lx\n",
                           iova);

#ifdef ENABLE_MARK_CLEAN
                if (dir == DMA_FROM_DEVICE) {
                        mark_clean(phys_to_virt(iova), size);
                }
#endif
                return;
        }
#endif
        offset = iova & ~iovp_mask;

        DBG_RUN("%s() iovp 0x%lx/%x\n", __func__, (long) iova, size);

        iova ^= offset;        /* clear offset bits */
        size += offset;
        size = ROUNDUP(size, iovp_size);

#ifdef ENABLE_MARK_CLEAN
        if (dir == DMA_FROM_DEVICE)
                sba_mark_clean(ioc, iova, size);
#endif

#if DELAYED_RESOURCE_CNT > 0
        spin_lock_irqsave(&ioc->saved_lock, flags);
        d = &(ioc->saved[ioc->saved_cnt]);
        d->iova = iova;
        d->size = size;
        if (unlikely(++(ioc->saved_cnt) >= DELAYED_RESOURCE_CNT)) {
                int cnt = ioc->saved_cnt;
                spin_lock(&ioc->res_lock);
                while (cnt--) {
                        sba_mark_invalid(ioc, d->iova, d->size);
                        sba_free_range(ioc, d->iova, d->size);
                        d--;
                }
                ioc->saved_cnt = 0;
                READ_REG(ioc->ioc_hpa+IOC_PCOM);        /* flush purges */
                spin_unlock(&ioc->res_lock);
        }
        spin_unlock_irqrestore(&ioc->saved_lock, flags);
#else /* DELAYED_RESOURCE_CNT == 0 */
        spin_lock_irqsave(&ioc->res_lock, flags);
        sba_mark_invalid(ioc, iova, size);
        sba_free_range(ioc, iova, size);
        READ_REG(ioc->ioc_hpa+IOC_PCOM);        /* flush purges */
        spin_unlock_irqrestore(&ioc->res_lock, flags);
#endif /* DELAYED_RESOURCE_CNT == 0 */
}

/**
 * sba_alloc_coherent - allocate/map shared mem for DMA
 * @dev: instance of PCI owned by the driver that's asking.
 * @size:  number of bytes mapped in driver buffer.
 * @dma_handle:  IOVA of new buffer.
 *
 * See Documentation/DMA-API-HOWTO.txt
 */
static void *
sba_alloc_coherent(struct device *dev, size_t size, dma_addr_t *dma_handle,
                   gfp_t flags, unsigned long attrs)
{
        struct page *page;
        struct ioc *ioc;
        int node = -1;
        void *addr;

        ioc = GET_IOC(dev);
        ASSERT(ioc);
#ifdef CONFIG_NUMA
        node = ioc->node;
#endif

        page = alloc_pages_node(node, flags, get_order(size));
        if (unlikely(!page))
                return NULL;

        addr = page_address(page);
        memset(addr, 0, size);
        *dma_handle = page_to_phys(page);

#ifdef ALLOW_IOV_BYPASS
        ASSERT(dev->coherent_dma_mask);
        /*
        ** Check if the PCI device can DMA to ptr... if so, just return ptr
        */
        if (likely((*dma_handle & ~dev->coherent_dma_mask) == 0)) {
                DBG_BYPASS("sba_alloc_coherent() bypass mask/addr: 0x%lx/0x%lx\n",
                           dev->coherent_dma_mask, *dma_handle);

                return addr;
        }
#endif

        /*
         * If device can't bypass or bypass is disabled, pass the 32bit fake
         * device to map single to get an iova mapping.
         */
        *dma_handle = sba_map_page(&ioc->sac_only_dev->dev, page, 0, size,
                        DMA_BIDIRECTIONAL, 0);
        if (dma_mapping_error(dev, *dma_handle))
                return NULL;
        return addr;
}


/**
 * sba_free_coherent - free/unmap shared mem for DMA
 * @dev: instance of PCI owned by the driver that's asking.
 * @size:  number of bytes mapped in driver buffer.
 * @vaddr:  virtual address IOVA of "consistent" buffer.
 * @dma_handler:  IO virtual address of "consistent" buffer.
 *
 * See Documentation/DMA-API-HOWTO.txt
 */
static void sba_free_coherent(struct device *dev, size_t size, void *vaddr,
                              dma_addr_t dma_handle, unsigned long attrs)
{
        sba_unmap_page(dev, dma_handle, size, 0, 0);
        free_pages((unsigned long) vaddr, get_order(size));
}


/*
** Since 0 is a valid pdir_base index value, can't use that
** to determine if a value is valid or not. Use a flag to indicate
** the SG list entry contains a valid pdir index.
*/
#define PIDE_FLAG 0x1UL

#ifdef DEBUG_LARGE_SG_ENTRIES
int dump_run_sg = 0;
#endif


/**
 * sba_fill_pdir - write allocated SG entries into IO PDIR
 * @ioc: IO MMU structure which owns the pdir we are interested in.
 * @startsg:  list of IOVA/size pairs
 * @nents: number of entries in startsg list
 *
 * Take preprocessed SG list and write corresponding entries
 * in the IO PDIR.
 */

static SBA_INLINE int
sba_fill_pdir(
        struct ioc *ioc,
        struct scatterlist *startsg,
        int nents)
{
        struct scatterlist *dma_sg = startsg;   /* pointer to current DMA */
        int n_mappings = 0;
        u64 *pdirp = NULL;
        unsigned long dma_offset = 0;

        while (nents-- > 0) {
                int     cnt = startsg->dma_length;
                startsg->dma_length = 0;

#ifdef DEBUG_LARGE_SG_ENTRIES
                if (dump_run_sg)
                        printk(" %2d : %08lx/%05x %p\n",
                                nents, startsg->dma_address, cnt,
                                sba_sg_address(startsg));
#else
                DBG_RUN_SG(" %d : %08lx/%05x %p\n",
                                nents, startsg->dma_address, cnt,
                                sba_sg_address(startsg));
#endif
                /*
                ** Look for the start of a new DMA stream
                */
                if (startsg->dma_address & PIDE_FLAG) {
                        u32 pide = startsg->dma_address & ~PIDE_FLAG;
                        dma_offset = (unsigned long) pide & ~iovp_mask;
                        startsg->dma_address = 0;
                        if (n_mappings)
                                dma_sg = sg_next(dma_sg);
                        dma_sg->dma_address = pide | ioc->ibase;
                        pdirp = &(ioc->pdir_base[pide >> iovp_shift]);
                        n_mappings++;
                }

                /*
                ** Look for a VCONTIG chunk
                */
                if (cnt) {
                        unsigned long vaddr = (unsigned long) sba_sg_address(startsg);
                        ASSERT(pdirp);

                        /* Since multiple Vcontig blocks could make up
                        ** one DMA stream, *add* cnt to dma_len.
                        */
                        dma_sg->dma_length += cnt;
                        cnt += dma_offset;
                        dma_offset=0;   /* only want offset on first chunk */
                        cnt = ROUNDUP(cnt, iovp_size);
                        do {
                                sba_io_pdir_entry(pdirp, vaddr);
                                vaddr += iovp_size;
                                cnt -= iovp_size;
                                pdirp++;
                        } while (cnt > 0);
                }
                startsg = sg_next(startsg);
        }
        /* force pdir update */
        wmb();

#ifdef DEBUG_LARGE_SG_ENTRIES
        dump_run_sg = 0;
#endif
        return(n_mappings);
}


/*
** Two address ranges are DMA contiguous *iff* "end of prev" and
** "start of next" are both on an IOV page boundary.
**
** (shift left is a quick trick to mask off upper bits)
*/
#define DMA_CONTIG(__X, __Y) \
        (((((unsigned long) __X) | ((unsigned long) __Y)) << (BITS_PER_LONG - iovp_shift)) == 0UL)


/**
 * sba_coalesce_chunks - preprocess the SG list
 * @ioc: IO MMU structure which owns the pdir we are interested in.
 * @startsg:  list of IOVA/size pairs
 * @nents: number of entries in startsg list
 *
 * First pass is to walk the SG list and determine where the breaks are
 * in the DMA stream. Allocates PDIR entries but does not fill them.
 * Returns the number of DMA chunks.
 *
 * Doing the fill separate from the coalescing/allocation keeps the
 * code simpler. Future enhancement could make one pass through
 * the sglist do both.
 */
static SBA_INLINE int
sba_coalesce_chunks(struct ioc *ioc, struct device *dev,
        struct scatterlist *startsg,
        int nents)
{
        struct scatterlist *vcontig_sg;    /* VCONTIG chunk head */
        unsigned long vcontig_len;         /* len of VCONTIG chunk */
        unsigned long vcontig_end;
        struct scatterlist *dma_sg;        /* next DMA stream head */
        unsigned long dma_offset, dma_len; /* start/len of DMA stream */
        int n_mappings = 0;
        unsigned int max_seg_size = dma_get_max_seg_size(dev);
        int idx;

        while (nents > 0) {
                unsigned long vaddr = (unsigned long) sba_sg_address(startsg);

                /*
                ** Prepare for first/next DMA stream
                */
                dma_sg = vcontig_sg = startsg;
                dma_len = vcontig_len = vcontig_end = startsg->length;
                vcontig_end +=  vaddr;
                dma_offset = vaddr & ~iovp_mask;

                /* PARANOID: clear entries */
                startsg->dma_address = startsg->dma_length = 0;

                /*
                ** This loop terminates one iteration "early" since
                ** it's always looking one "ahead".
                */
                while (--nents > 0) {
                        unsigned long vaddr;    /* tmp */

                        startsg = sg_next(startsg);

                        /* PARANOID */
                        startsg->dma_address = startsg->dma_length = 0;

                        /* catch brokenness in SCSI layer */
                        ASSERT(startsg->length <= DMA_CHUNK_SIZE);

                        /*
                        ** First make sure current dma stream won't
                        ** exceed DMA_CHUNK_SIZE if we coalesce the
                        ** next entry.
                        */
                        if (((dma_len + dma_offset + startsg->length + ~iovp_mask) & iovp_mask)
                            > DMA_CHUNK_SIZE)
                                break;

                        if (dma_len + startsg->length > max_seg_size)
                                break;

                        /*
                        ** Then look for virtually contiguous blocks.
                        **
                        ** append the next transaction?
                        */
                        vaddr = (unsigned long) sba_sg_address(startsg);
                        if  (vcontig_end == vaddr)
                        {
                                vcontig_len += startsg->length;
                                vcontig_end += startsg->length;
                                dma_len     += startsg->length;
                                continue;
                        }

#ifdef DEBUG_LARGE_SG_ENTRIES
                        dump_run_sg = (vcontig_len > iovp_size);
#endif

                        /*
                        ** Not virtually contiguous.
                        ** Terminate prev chunk.
                        ** Start a new chunk.
                        **
                        ** Once we start a new VCONTIG chunk, dma_offset
                        ** can't change. And we need the offset from the first
                        ** chunk - not the last one. Ergo Successive chunks
                        ** must start on page boundaries and dove tail
                        ** with it's predecessor.
                        */
                        vcontig_sg->dma_length = vcontig_len;

                        vcontig_sg = startsg;
                        vcontig_len = startsg->length;

                        /*
                        ** 3) do the entries end/start on page boundaries?
                        **    Don't update vcontig_end until we've checked.
                        */
                        if (DMA_CONTIG(vcontig_end, vaddr))
                        {
                                vcontig_end = vcontig_len + vaddr;
                                dma_len += vcontig_len;
                                continue;
                        } else {
                                break;
                        }
                }

                /*
                ** End of DMA Stream
                ** Terminate last VCONTIG block.
                ** Allocate space for DMA stream.
                */
                vcontig_sg->dma_length = vcontig_len;
                dma_len = (dma_len + dma_offset + ~iovp_mask) & iovp_mask;
                ASSERT(dma_len <= DMA_CHUNK_SIZE);
                idx = sba_alloc_range(ioc, dev, dma_len);
                if (idx < 0) {
                        dma_sg->dma_length = 0;
                        return -1;
                }
                dma_sg->dma_address = (dma_addr_t)(PIDE_FLAG | (idx << iovp_shift)
                                                   | dma_offset);
                n_mappings++;
        }

        return n_mappings;
}

static void sba_unmap_sg_attrs(struct device *dev, struct scatterlist *sglist,
                               int nents, enum dma_data_direction dir,
                               unsigned long attrs);
/**
 * sba_map_sg - map Scatter/Gather list
 * @dev: instance of PCI owned by the driver that's asking.
 * @sglist:  array of buffer/length pairs
 * @nents:  number of entries in list
 * @dir:  R/W or both.
 * @attrs: optional dma attributes
 *
 * See Documentation/DMA-API-HOWTO.txt
 */
static int sba_map_sg_attrs(struct device *dev, struct scatterlist *sglist,
                            int nents, enum dma_data_direction dir,
                            unsigned long attrs)
{
        struct ioc *ioc;
        int coalesced, filled = 0;
#ifdef ASSERT_PDIR_SANITY
        unsigned long flags;
#endif
#ifdef ALLOW_IOV_BYPASS_SG
        struct scatterlist *sg;
#endif

        DBG_RUN_SG("%s() START %d entries\n", __func__, nents);
        ioc = GET_IOC(dev);
        ASSERT(ioc);

#ifdef ALLOW_IOV_BYPASS_SG
        ASSERT(to_pci_dev(dev)->dma_mask);
        if (likely((ioc->dma_mask & ~to_pci_dev(dev)->dma_mask) == 0)) {
                for_each_sg(sglist, sg, nents, filled) {
                        sg->dma_length = sg->length;
                        sg->dma_address = virt_to_phys(sba_sg_address(sg));
                }
                return filled;
        }
#endif
        /* Fast path single entry scatterlists. */
        if (nents == 1) {
                sglist->dma_length = sglist->length;
                sglist->dma_address = sba_map_page(dev, sg_page(sglist),
                                sglist->offset, sglist->length, dir, attrs);
                if (dma_mapping_error(dev, sglist->dma_address))
                        return 0;
                return 1;
        }

#ifdef ASSERT_PDIR_SANITY
        spin_lock_irqsave(&ioc->res_lock, flags);
        if (sba_check_pdir(ioc,"Check before sba_map_sg_attrs()"))
        {
                sba_dump_sg(ioc, sglist, nents);
                panic("Check before sba_map_sg_attrs()");
        }
        spin_unlock_irqrestore(&ioc->res_lock, flags);
#endif

        prefetch(ioc->res_hint);

        /*
        ** First coalesce the chunks and allocate I/O pdir space
        **
        ** If this is one DMA stream, we can properly map using the
        ** correct virtual address associated with each DMA page.
        ** w/o this association, we wouldn't have coherent DMA!
        ** Access to the virtual address is what forces a two pass algorithm.
        */
        coalesced = sba_coalesce_chunks(ioc, dev, sglist, nents);
        if (coalesced < 0) {
                sba_unmap_sg_attrs(dev, sglist, nents, dir, attrs);
                return 0;
        }

        /*
        ** Program the I/O Pdir
        **
        ** map the virtual addresses to the I/O Pdir
        ** o dma_address will contain the pdir index
        ** o dma_len will contain the number of bytes to map
        ** o address contains the virtual address.
        */
        filled = sba_fill_pdir(ioc, sglist, nents);

#ifdef ASSERT_PDIR_SANITY
        spin_lock_irqsave(&ioc->res_lock, flags);
        if (sba_check_pdir(ioc,"Check after sba_map_sg_attrs()"))
        {
                sba_dump_sg(ioc, sglist, nents);
                panic("Check after sba_map_sg_attrs()\n");
        }
        spin_unlock_irqrestore(&ioc->res_lock, flags);
#endif

        ASSERT(coalesced == filled);
        DBG_RUN_SG("%s() DONE %d mappings\n", __func__, filled);

        return filled;
}

/**
 * sba_unmap_sg_attrs - unmap Scatter/Gather list
 * @dev: instance of PCI owned by the driver that's asking.
 * @sglist:  array of buffer/length pairs
 * @nents:  number of entries in list
 * @dir:  R/W or both.
 * @attrs: optional dma attributes
 *
 * See Documentation/DMA-API-HOWTO.txt
 */
static void sba_unmap_sg_attrs(struct device *dev, struct scatterlist *sglist,
                               int nents, enum dma_data_direction dir,
                               unsigned long attrs)
{
#ifdef ASSERT_PDIR_SANITY
        struct ioc *ioc;
        unsigned long flags;
#endif

        DBG_RUN_SG("%s() START %d entries,  %p,%x\n",
                   __func__, nents, sba_sg_address(sglist), sglist->length);

#ifdef ASSERT_PDIR_SANITY
        ioc = GET_IOC(dev);
        ASSERT(ioc);

        spin_lock_irqsave(&ioc->res_lock, flags);
        sba_check_pdir(ioc,"Check before sba_unmap_sg_attrs()");
        spin_unlock_irqrestore(&ioc->res_lock, flags);
#endif

        while (nents && sglist->dma_length) {

                sba_unmap_page(dev, sglist->dma_address, sglist->dma_length,
                               dir, attrs);
                sglist = sg_next(sglist);
                nents--;
        }

        DBG_RUN_SG("%s() DONE (nents %d)\n", __func__,  nents);

#ifdef ASSERT_PDIR_SANITY
        spin_lock_irqsave(&ioc->res_lock, flags);
        sba_check_pdir(ioc,"Check after sba_unmap_sg_attrs()");
        spin_unlock_irqrestore(&ioc->res_lock, flags);
#endif

}

/**************************************************************
*
*   Initialization and claim
*
***************************************************************/

static void
ioc_iova_init(struct ioc *ioc)
{
        int tcnfg;
        int agp_found = 0;
        struct pci_dev *device = NULL;
#ifdef FULL_VALID_PDIR
        unsigned long index;
#endif

        /*
        ** Firmware programs the base and size of a "safe IOVA space"
        ** (one that doesn't overlap memory or LMMIO space) in the
        ** IBASE and IMASK registers.
        */
        ioc->ibase = READ_REG(ioc->ioc_hpa + IOC_IBASE) & ~0x1UL;
        ioc->imask = READ_REG(ioc->ioc_hpa + IOC_IMASK) | 0xFFFFFFFF00000000UL;

        ioc->iov_size = ~ioc->imask + 1;

        DBG_INIT("%s() hpa %p IOV base 0x%lx mask 0x%lx (%dMB)\n",
                __func__, ioc->ioc_hpa, ioc->ibase, ioc->imask,
                ioc->iov_size >> 20);

        switch (iovp_size) {
                case  4*1024: tcnfg = 0; break;
                case  8*1024: tcnfg = 1; break;
                case 16*1024: tcnfg = 2; break;
                case 64*1024: tcnfg = 3; break;
                default:
                        panic(PFX "Unsupported IOTLB page size %ldK",
                                iovp_size >> 10);
                        break;
        }
        WRITE_REG(tcnfg, ioc->ioc_hpa + IOC_TCNFG);

        ioc->pdir_size = (ioc->iov_size / iovp_size) * PDIR_ENTRY_SIZE;
        ioc->pdir_base = (void *) __get_free_pages(GFP_KERNEL,
                                                   get_order(ioc->pdir_size));
        if (!ioc->pdir_base)
                panic(PFX "Couldn't allocate I/O Page Table\n");

        memset(ioc->pdir_base, 0, ioc->pdir_size);

        DBG_INIT("%s() IOV page size %ldK pdir %p size %x\n", __func__,
                iovp_size >> 10, ioc->pdir_base, ioc->pdir_size);

        ASSERT(ALIGN((unsigned long) ioc->pdir_base, 4*1024) == (unsigned long) ioc->pdir_base);
        WRITE_REG(virt_to_phys(ioc->pdir_base), ioc->ioc_hpa + IOC_PDIR_BASE);

        /*
        ** If an AGP device is present, only use half of the IOV space
        ** for PCI DMA.  Unfortunately we can't know ahead of time
        ** whether GART support will actually be used, for now we
        ** can just key on an AGP device found in the system.
        ** We program the next pdir index after we stop w/ a key for
        ** the GART code to handshake on.
        */
        for_each_pci_dev(device)        
                agp_found |= pci_find_capability(device, PCI_CAP_ID_AGP);

        if (agp_found && reserve_sba_gart) {
                printk(KERN_INFO PFX "reserving %dMb of IOVA space at 0x%lx for agpgart\n",
                      ioc->iov_size/2 >> 20, ioc->ibase + ioc->iov_size/2);
                ioc->pdir_size /= 2;
                ((u64 *)ioc->pdir_base)[PDIR_INDEX(ioc->iov_size/2)] = ZX1_SBA_IOMMU_COOKIE;
        }
#ifdef FULL_VALID_PDIR
        /*
        ** Check to see if the spill page has been allocated, we don't need more than
        ** one across multiple SBAs.
        */
        if (!prefetch_spill_page) {
                char *spill_poison = "SBAIOMMU POISON";
                int poison_size = 16;
                void *poison_addr, *addr;

                addr = (void *)__get_free_pages(GFP_KERNEL, get_order(iovp_size));
                if (!addr)
                        panic(PFX "Couldn't allocate PDIR spill page\n");

                poison_addr = addr;
                for ( ; (u64) poison_addr < addr + iovp_size; poison_addr += poison_size)
                        memcpy(poison_addr, spill_poison, poison_size);

                prefetch_spill_page = virt_to_phys(addr);

                DBG_INIT("%s() prefetch spill addr: 0x%lx\n", __func__, prefetch_spill_page);
        }
        /*
        ** Set all the PDIR entries valid w/ the spill page as the target
        */
        for (index = 0 ; index < (ioc->pdir_size / PDIR_ENTRY_SIZE) ; index++)
                ((u64 *)ioc->pdir_base)[index] = (0x80000000000000FF | prefetch_spill_page);
#endif

        /* Clear I/O TLB of any possible entries */
        WRITE_REG(ioc->ibase | (get_iovp_order(ioc->iov_size) + iovp_shift), ioc->ioc_hpa + IOC_PCOM);
        READ_REG(ioc->ioc_hpa + IOC_PCOM);

        /* Enable IOVA translation */
        WRITE_REG(ioc->ibase | 1, ioc->ioc_hpa + IOC_IBASE);
        READ_REG(ioc->ioc_hpa + IOC_IBASE);
}

static void __init
ioc_resource_init(struct ioc *ioc)
{
        spin_lock_init(&ioc->res_lock);
#if DELAYED_RESOURCE_CNT > 0
        spin_lock_init(&ioc->saved_lock);
#endif

        /* resource map size dictated by pdir_size */
        ioc->res_size = ioc->pdir_size / PDIR_ENTRY_SIZE; /* entries */
        ioc->res_size >>= 3;  /* convert bit count to byte count */
        DBG_INIT("%s() res_size 0x%x\n", __func__, ioc->res_size);

        ioc->res_map = (char *) __get_free_pages(GFP_KERNEL,
                                                 get_order(ioc->res_size));
        if (!ioc->res_map)
                panic(PFX "Couldn't allocate resource map\n");

        memset(ioc->res_map, 0, ioc->res_size);
        /* next available IOVP - circular search */
        ioc->res_hint = (unsigned long *) ioc->res_map;

#ifdef ASSERT_PDIR_SANITY
        /* Mark first bit busy - ie no IOVA 0 */
        ioc->res_map[0] = 0x1;
        ioc->pdir_base[0] = 0x8000000000000000ULL | ZX1_SBA_IOMMU_COOKIE;
#endif
#ifdef FULL_VALID_PDIR
        /* Mark the last resource used so we don't prefetch beyond IOVA space */
        ioc->res_map[ioc->res_size - 1] |= 0x80UL; /* res_map is chars */
        ioc->pdir_base[(ioc->pdir_size / PDIR_ENTRY_SIZE) - 1] = (0x80000000000000FF
                                                              | prefetch_spill_page);
#endif

        DBG_INIT("%s() res_map %x %p\n", __func__,
                 ioc->res_size, (void *) ioc->res_map);
}

static void __init
ioc_sac_init(struct ioc *ioc)
{
        struct pci_dev *sac = NULL;
        struct pci_controller *controller = NULL;

        /*
         * pci_alloc_coherent() must return a DMA address which is
         * SAC (single address cycle) addressable, so allocate a
         * pseudo-device to enforce that.
         */
        sac = kzalloc(sizeof(*sac), GFP_KERNEL);
        if (!sac)
                panic(PFX "Couldn't allocate struct pci_dev");

        controller = kzalloc(sizeof(*controller), GFP_KERNEL);
        if (!controller)
                panic(PFX "Couldn't allocate struct pci_controller");

        controller->iommu = ioc;
        sac->sysdata = controller;
        sac->dma_mask = 0xFFFFFFFFUL;
        sac->dev.bus = &pci_bus_type;
        ioc->sac_only_dev = sac;
}

static void __init
ioc_zx1_init(struct ioc *ioc)
{
        unsigned long rope_config;
        unsigned int i;

        if (ioc->rev < 0x20)
                panic(PFX "IOC 2.0 or later required for IOMMU support\n");

        /* 38 bit memory controller + extra bit for range displaced by MMIO */
        ioc->dma_mask = (0x1UL << 39) - 1;

        /*
        ** Clear ROPE(N)_CONFIG AO bit.
        ** Disables "NT Ordering" (~= !"Relaxed Ordering")
        ** Overrides bit 1 in DMA Hint Sets.
        ** Improves netperf UDP_STREAM by ~10% for tg3 on bcm5701.
        */
        for (i=0; i<(8*8); i+=8) {
                rope_config = READ_REG(ioc->ioc_hpa + IOC_ROPE0_CFG + i);
                rope_config &= ~IOC_ROPE_AO;
                WRITE_REG(rope_config, ioc->ioc_hpa + IOC_ROPE0_CFG + i);
        }
}

typedef void (initfunc)(struct ioc *);

struct ioc_iommu {
        u32 func_id;
        char *name;
        initfunc *init;
};

static struct ioc_iommu ioc_iommu_info[] __initdata = {
        { ZX1_IOC_ID, "zx1", ioc_zx1_init },
        { ZX2_IOC_ID, "zx2", NULL },
        { SX1000_IOC_ID, "sx1000", NULL },
        { SX2000_IOC_ID, "sx2000", NULL },
};

static void __init ioc_init(unsigned long hpa, struct ioc *ioc)
{
        struct ioc_iommu *info;

        ioc->next = ioc_list;
        ioc_list = ioc;

        ioc->ioc_hpa = ioremap(hpa, 0x1000);

        ioc->func_id = READ_REG(ioc->ioc_hpa + IOC_FUNC_ID);
        ioc->rev = READ_REG(ioc->ioc_hpa + IOC_FCLASS) & 0xFFUL;
        ioc->dma_mask = 0xFFFFFFFFFFFFFFFFUL;   /* conservative */

        for (info = ioc_iommu_info; info < ioc_iommu_info + ARRAY_SIZE(ioc_iommu_info); info++) {
                if (ioc->func_id == info->func_id) {
                        ioc->name = info->name;
                        if (info->init)
                                (info->init)(ioc);
                }
        }

        iovp_size = (1 << iovp_shift);
        iovp_mask = ~(iovp_size - 1);

        DBG_INIT("%s: PAGE_SIZE %ldK, iovp_size %ldK\n", __func__,
                PAGE_SIZE >> 10, iovp_size >> 10);

        if (!ioc->name) {
                ioc->name = kmalloc(24, GFP_KERNEL);
                if (ioc->name)
                        sprintf((char *) ioc->name, "Unknown (%04x:%04x)",
                                ioc->func_id & 0xFFFF, (ioc->func_id >> 16) & 0xFFFF);
                else
                        ioc->name = "Unknown";
        }

        ioc_iova_init(ioc);
        ioc_resource_init(ioc);
        ioc_sac_init(ioc);

        printk(KERN_INFO PFX
                "%s %d.%d HPA 0x%lx IOVA space %dMb at 0x%lx\n",
                ioc->name, (ioc->rev >> 4) & 0xF, ioc->rev & 0xF,
                hpa, ioc->iov_size >> 20, ioc->ibase);
}



/**************************************************************************
**
**   SBA initialization code (HW and SW)
**
**   o identify SBA chip itself
**   o FIXME: initialize DMA hints for reasonable defaults
**
**************************************************************************/

#ifdef CONFIG_PROC_FS
static void *
ioc_start(struct seq_file *s, loff_t *pos)
{
        struct ioc *ioc;
        loff_t n = *pos;

        for (ioc = ioc_list; ioc; ioc = ioc->next)
                if (!n--)
                        return ioc;

        return NULL;
}

static void *
ioc_next(struct seq_file *s, void *v, loff_t *pos)
{
        struct ioc *ioc = v;

        ++*pos;
        return ioc->next;
}

static void
ioc_stop(struct seq_file *s, void *v)
{
}

static int
ioc_show(struct seq_file *s, void *v)
{
        struct ioc *ioc = v;
        unsigned long *res_ptr = (unsigned long *)ioc->res_map;
        int i, used = 0;

        seq_printf(s, "Hewlett Packard %s IOC rev %d.%d\n",
                ioc->name, ((ioc->rev >> 4) & 0xF), (ioc->rev & 0xF));
#ifdef CONFIG_NUMA
        if (ioc->node != NUMA_NO_NODE)
                seq_printf(s, "NUMA node       : %d\n", ioc->node);
#endif
        seq_printf(s, "IOVA size       : %ld MB\n", ((ioc->pdir_size >> 3) * iovp_size)/(1024*1024));
        seq_printf(s, "IOVA page size  : %ld kb\n", iovp_size/1024);

        for (i = 0; i < (ioc->res_size / sizeof(unsigned long)); ++i, ++res_ptr)
                used += hweight64(*res_ptr);

        seq_printf(s, "PDIR size       : %d entries\n", ioc->pdir_size >> 3);
        seq_printf(s, "PDIR used       : %d entries\n", used);

#ifdef PDIR_SEARCH_TIMING
        {
                unsigned long i = 0, avg = 0, min, max;
                min = max = ioc->avg_search[0];
                for (i = 0; i < SBA_SEARCH_SAMPLE; i++) {
                        avg += ioc->avg_search[i];
                        if (ioc->avg_search[i] > max) max = ioc->avg_search[i];
                        if (ioc->avg_search[i] < min) min = ioc->avg_search[i];
                }
                avg /= SBA_SEARCH_SAMPLE;
                seq_printf(s, "Bitmap search   : %ld/%ld/%ld (min/avg/max CPU Cycles/IOVA page)\n",
                           min, avg, max);
        }
#endif
#ifndef ALLOW_IOV_BYPASS
         seq_printf(s, "IOVA bypass disabled\n");
#endif
        return 0;
}

static const struct seq_operations ioc_seq_ops = {
        .start = ioc_start,
        .next  = ioc_next,
        .stop  = ioc_stop,
        .show  = ioc_show
};

static void __init
ioc_proc_init(void)
{
        struct proc_dir_entry *dir;

        dir = proc_mkdir("bus/mckinley", NULL);
        if (!dir)
                return;

        proc_create_seq(ioc_list->name, 0, dir, &ioc_seq_ops);
}
#endif

static void
sba_connect_bus(struct pci_bus *bus)
{
        acpi_handle handle, parent;
        acpi_status status;
        struct ioc *ioc;

        if (!PCI_CONTROLLER(bus))
                panic(PFX "no sysdata on bus %d!\n", bus->number);

        if (PCI_CONTROLLER(bus)->iommu)
                return;

        handle = acpi_device_handle(PCI_CONTROLLER(bus)->companion);
        if (!handle)
                return;

        /*
         * The IOC scope encloses PCI root bridges in the ACPI
         * namespace, so work our way out until we find an IOC we
         * claimed previously.
         */
        do {
                for (ioc = ioc_list; ioc; ioc = ioc->next)
                        if (ioc->handle == handle) {
                                PCI_CONTROLLER(bus)->iommu = ioc;
                                return;
                        }

                status = acpi_get_parent(handle, &parent);
                handle = parent;
        } while (ACPI_SUCCESS(status));

        printk(KERN_WARNING "No IOC for PCI Bus %04x:%02x in ACPI\n", pci_domain_nr(bus), bus->number);
}

static void __init
sba_map_ioc_to_node(struct ioc *ioc, acpi_handle handle)
{
#ifdef CONFIG_NUMA
        unsigned int node;

        node = acpi_get_node(handle);
        if (node != NUMA_NO_NODE && !node_online(node))
                node = NUMA_NO_NODE;

        ioc->node = node;
#endif
}

static void __init acpi_sba_ioc_add(struct ioc *ioc)
{
        acpi_handle handle = ioc->handle;
        acpi_status status;
        u64 hpa, length;
        struct acpi_device_info *adi;

        ioc_found = ioc->next;
        status = hp_acpi_csr_space(handle, &hpa, &length);
        if (ACPI_FAILURE(status))
                goto err;

        status = acpi_get_object_info(handle, &adi);
        if (ACPI_FAILURE(status))
                goto err;

        /*
         * For HWP0001, only SBA appears in ACPI namespace.  It encloses the PCI
         * root bridges, and its CSR space includes the IOC function.
         */
        if (strncmp("HWP0001", adi->hardware_id.string, 7) == 0) {
                hpa += ZX1_IOC_OFFSET;
                /* zx1 based systems default to kernel page size iommu pages */
                if (!iovp_shift)
                        iovp_shift = min(PAGE_SHIFT, 16);
        }
        kfree(adi);

        /*
         * default anything not caught above or specified on cmdline to 4k
         * iommu page size
         */
        if (!iovp_shift)
                iovp_shift = 12;

        ioc_init(hpa, ioc);
        /* setup NUMA node association */
        sba_map_ioc_to_node(ioc, handle);
        return;

 err:
        kfree(ioc);
}

static const struct acpi_device_id hp_ioc_iommu_device_ids[] = {
        {"HWP0001", 0},
        {"HWP0004", 0},
        {"", 0},
};

static int acpi_sba_ioc_attach(struct acpi_device *device,
                               const struct acpi_device_id *not_used)
{
        struct ioc *ioc;

        ioc = kzalloc(sizeof(*ioc), GFP_KERNEL);
        if (!ioc)
                return -ENOMEM;

        ioc->next = ioc_found;
        ioc_found = ioc;
        ioc->handle = device->handle;
        return 1;
}


static struct acpi_scan_handler acpi_sba_ioc_handler = {
        .ids    = hp_ioc_iommu_device_ids,
        .attach = acpi_sba_ioc_attach,
};

static int __init acpi_sba_ioc_init_acpi(void)
{
        return acpi_scan_add_handler(&acpi_sba_ioc_handler);
}
/* This has to run before acpi_scan_init(). */
arch_initcall(acpi_sba_ioc_init_acpi);

static int sba_dma_supported (struct device *dev, u64 mask)
{
        /* make sure it's at least 32bit capable */
        return ((mask & 0xFFFFFFFFUL) == 0xFFFFFFFFUL);
}

static const struct dma_map_ops sba_dma_ops = {
        .alloc                  = sba_alloc_coherent,
        .free                   = sba_free_coherent,
        .map_page               = sba_map_page,
        .unmap_page             = sba_unmap_page,
        .map_sg                 = sba_map_sg_attrs,
        .unmap_sg               = sba_unmap_sg_attrs,
        .dma_supported          = sba_dma_supported,
        .mmap                   = dma_common_mmap,
        .get_sgtable            = dma_common_get_sgtable,
};

static int __init
sba_init(void)
{
        /*
         * If we are booting a kdump kernel, the sba_iommu will cause devices
         * that were not shutdown properly to MCA as soon as they are turned
         * back on.  Our only option for a successful kdump kernel boot is to
         * use swiotlb.
         */
        if (is_kdump_kernel())
                return 0;

        /*
         * ioc_found should be populated by the acpi_sba_ioc_handler's .attach()
         * routine, but that only happens if acpi_scan_init() has already run.
         */
        while (ioc_found)
                acpi_sba_ioc_add(ioc_found);

        if (!ioc_list)
                return 0;

        {
                struct pci_bus *b = NULL;
                while ((b = pci_find_next_bus(b)) != NULL)
                        sba_connect_bus(b);
        }

        /* no need for swiotlb with the iommu */
        swiotlb_exit();
        dma_ops = &sba_dma_ops;

#ifdef CONFIG_PROC_FS
        ioc_proc_init();
#endif
        return 0;
}

subsys_initcall(sba_init); /* must be initialized after ACPI etc., but before any drivers... */

static int __init
nosbagart(char *str)
{
        reserve_sba_gart = 0;
        return 1;
}

__setup("nosbagart", nosbagart);

static int __init
sba_page_override(char *str)
{
        unsigned long page_size;

        page_size = memparse(str, &str);
        switch (page_size) {
                case 4096:
                case 8192:
                case 16384:
                case 65536:
                        iovp_shift = ffs(page_size) - 1;
                        break;
                default:
                        printk("%s: unknown/unsupported iommu page size %ld\n",
                               __func__, page_size);
        }

        return 1;
}

__setup("sbapagesize=",sba_page_override);