/*
 * Copyright (C) 2001 Mike Corrigan & Dave Engebretsen, IBM Corporation
 * 
 * Rewrite, cleanup, new allocation schemes, virtual merging: 
 * Copyright (C) 2004 Olof Johansson, IBM Corporation
 *               and  Ben. Herrenschmidt, IBM Corporation
 *
 * Dynamic DMA mapping support, bus-independent parts.
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 * 
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 * 
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307 USA
 */


#include <linux/init.h>
#include <linux/types.h>
#include <linux/slab.h>
#include <linux/mm.h>
#include <linux/spinlock.h>
#include <linux/string.h>
#include <linux/dma-mapping.h>
#include <linux/bitops.h>
#include <linux/iommu-helper.h>
#include <asm/io.h>
#include <asm/prom.h>
#include <asm/iommu.h>
#include <asm/pci-bridge.h>
#include <asm/machdep.h>
#include <asm/kdump.h>

#define DBG(...)

#ifdef CONFIG_IOMMU_VMERGE
static int novmerge = 0;
#else
static int novmerge = 1;
#endif

static int protect4gb = 1;

static inline unsigned long iommu_num_pages(unsigned long vaddr,
                                            unsigned long slen)
{
        unsigned long npages;

        npages = IOMMU_PAGE_ALIGN(vaddr + slen) - (vaddr & IOMMU_PAGE_MASK);
        npages >>= IOMMU_PAGE_SHIFT;

        return npages;
}

static int __init setup_protect4gb(char *str)
{
        if (strcmp(str, "on") == 0)
                protect4gb = 1;
        else if (strcmp(str, "off") == 0)
                protect4gb = 0;

        return 1;
}

static int __init setup_iommu(char *str)
{
        if (!strcmp(str, "novmerge"))
                novmerge = 1;
        else if (!strcmp(str, "vmerge"))
                novmerge = 0;
        return 1;
}

__setup("protect4gb=", setup_protect4gb);
__setup("iommu=", setup_iommu);

static unsigned long iommu_range_alloc(struct device *dev,
                                       struct iommu_table *tbl,
                                       unsigned long npages,
                                       unsigned long *handle,
                                       unsigned long mask,
                                       unsigned int align_order)
{ 
        unsigned long n, end, start;
        unsigned long limit;
        int largealloc = npages > 15;
        int pass = 0;
        unsigned long align_mask;
        unsigned long boundary_size;

        align_mask = 0xffffffffffffffffl >> (64 - align_order);

        /* 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 = largealloc ? tbl->it_largehint : tbl->it_hint;

        /* Use only half of the table for small allocs (15 pages or less) */
        limit = largealloc ? tbl->it_size : tbl->it_halfpoint;

        if (largealloc && start < tbl->it_halfpoint)
                start = tbl->it_halfpoint;

        /* 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 initial start.
         */
        if (start >= limit)
                start = largealloc ? tbl->it_largehint : tbl->it_hint;

 again:

        if (limit + tbl->it_offset > mask) {
                limit = mask - tbl->it_offset + 1;
                /* If we're constrained on address range, first try
                 * at the masked hint to avoid O(n) search complexity,
                 * but on second pass, start at 0.
                 */
                if ((start & mask) >= limit || pass > 0)
                        start = 0;
                else
                        start &= mask;
        }

        if (dev)
                boundary_size = ALIGN(dma_get_seg_boundary(dev) + 1,
                                      1 << IOMMU_PAGE_SHIFT);
        else
                boundary_size = ALIGN(1UL << 32, 1 << IOMMU_PAGE_SHIFT);
        /* 4GB boundary for iseries_hv_alloc and iseries_hv_map */

        n = iommu_area_alloc(tbl->it_map, limit, start, npages,
                             tbl->it_offset, boundary_size >> IOMMU_PAGE_SHIFT,
                             align_mask);
        if (n == -1) {
                if (likely(pass < 2)) {
                        /* First failure, just rescan the half of the table.
                         * Second failure, rescan the other half of the table.
                         */
                        start = (largealloc ^ pass) ? tbl->it_halfpoint : 0;
                        limit = pass ? tbl->it_size : limit;
                        pass++;
                        goto again;
                } else {
                        /* Third failure, give up */
                        return DMA_ERROR_CODE;
                }
        }

        end = n + npages;

        /* Bump the hint to a new block for small allocs. */
        if (largealloc) {
                /* Don't bump to new block to avoid fragmentation */
                tbl->it_largehint = end;
        } else {
                /* Overflow will be taken care of at the next allocation */
                tbl->it_hint = (end + tbl->it_blocksize - 1) &
                                ~(tbl->it_blocksize - 1);
        }

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

        return n;
}

static dma_addr_t iommu_alloc(struct device *dev, struct iommu_table *tbl,
                              void *page, unsigned int npages,
                              enum dma_data_direction direction,
                              unsigned long mask, unsigned int align_order)
{
        unsigned long entry, flags;
        dma_addr_t ret = DMA_ERROR_CODE;

        spin_lock_irqsave(&(tbl->it_lock), flags);

        entry = iommu_range_alloc(dev, tbl, npages, NULL, mask, align_order);

        if (unlikely(entry == DMA_ERROR_CODE)) {
                spin_unlock_irqrestore(&(tbl->it_lock), flags);
                return DMA_ERROR_CODE;
        }

        entry += tbl->it_offset;        /* Offset into real TCE table */
        ret = entry << IOMMU_PAGE_SHIFT;        /* Set the return dma address */

        /* Put the TCEs in the HW table */
        ppc_md.tce_build(tbl, entry, npages, (unsigned long)page & IOMMU_PAGE_MASK,
                         direction);


        /* Flush/invalidate TLB caches if necessary */
        if (ppc_md.tce_flush)
                ppc_md.tce_flush(tbl);

        spin_unlock_irqrestore(&(tbl->it_lock), flags);

        /* Make sure updates are seen by hardware */
        mb();

        return ret;
}

static void __iommu_free(struct iommu_table *tbl, dma_addr_t dma_addr, 
                         unsigned int npages)
{
        unsigned long entry, free_entry;

        entry = dma_addr >> IOMMU_PAGE_SHIFT;
        free_entry = entry - tbl->it_offset;

        if (((free_entry + npages) > tbl->it_size) ||
            (entry < tbl->it_offset)) {
                if (printk_ratelimit()) {
                        printk(KERN_INFO "iommu_free: invalid entry\n");
                        printk(KERN_INFO "\tentry     = 0x%lx\n", entry); 
                        printk(KERN_INFO "\tdma_addr  = 0x%lx\n", (u64)dma_addr);
                        printk(KERN_INFO "\tTable     = 0x%lx\n", (u64)tbl);
                        printk(KERN_INFO "\tbus#      = 0x%lx\n", (u64)tbl->it_busno);
                        printk(KERN_INFO "\tsize      = 0x%lx\n", (u64)tbl->it_size);
                        printk(KERN_INFO "\tstartOff  = 0x%lx\n", (u64)tbl->it_offset);
                        printk(KERN_INFO "\tindex     = 0x%lx\n", (u64)tbl->it_index);
                        WARN_ON(1);
                }
                return;
        }

        ppc_md.tce_free(tbl, entry, npages);
        iommu_area_free(tbl->it_map, free_entry, npages);
}

static void iommu_free(struct iommu_table *tbl, dma_addr_t dma_addr,
                unsigned int npages)
{
        unsigned long flags;

        spin_lock_irqsave(&(tbl->it_lock), flags);

        __iommu_free(tbl, dma_addr, npages);

        /* Make sure TLB cache is flushed if the HW needs it. We do
         * not do an mb() here on purpose, it is not needed on any of
         * the current platforms.
         */
        if (ppc_md.tce_flush)
                ppc_md.tce_flush(tbl);

        spin_unlock_irqrestore(&(tbl->it_lock), flags);
}

int iommu_map_sg(struct device *dev, struct scatterlist *sglist,
                 int nelems, unsigned long mask,
                 enum dma_data_direction direction)
{
        struct iommu_table *tbl = dev->archdata.dma_data;
        dma_addr_t dma_next = 0, dma_addr;
        unsigned long flags;
        struct scatterlist *s, *outs, *segstart;
        int outcount, incount, i;
        unsigned int align;
        unsigned long handle;
        unsigned int max_seg_size;

        BUG_ON(direction == DMA_NONE);

        if ((nelems == 0) || !tbl)
                return 0;

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

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

        DBG("sg mapping %d elements:\n", nelems);

        spin_lock_irqsave(&(tbl->it_lock), flags);

        max_seg_size = dma_get_max_seg_size(dev);
        for_each_sg(sglist, s, nelems, i) {
                unsigned long vaddr, npages, entry, slen;

                slen = s->length;
                /* Sanity check */
                if (slen == 0) {
                        dma_next = 0;
                        continue;
                }
                /* Allocate iommu entries for that segment */
                vaddr = (unsigned long) sg_virt(s);
                npages = iommu_num_pages(vaddr, slen);
                align = 0;
                if (IOMMU_PAGE_SHIFT < PAGE_SHIFT && slen >= PAGE_SIZE &&
                    (vaddr & ~PAGE_MASK) == 0)
                        align = PAGE_SHIFT - IOMMU_PAGE_SHIFT;
                entry = iommu_range_alloc(dev, tbl, npages, &handle,
                                          mask >> IOMMU_PAGE_SHIFT, align);

                DBG("  - vaddr: %lx, size: %lx\n", vaddr, slen);

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

                /* Convert entry to a dma_addr_t */
                entry += tbl->it_offset;
                dma_addr = entry << IOMMU_PAGE_SHIFT;
                dma_addr |= (s->offset & ~IOMMU_PAGE_MASK);

                DBG("  - %lu pages, entry: %lx, dma_addr: %lx\n",
                            npages, entry, dma_addr);

                /* Insert into HW table */
                ppc_md.tce_build(tbl, entry, npages, vaddr & IOMMU_PAGE_MASK, direction);

                /* If we are in an open segment, try merging */
                if (segstart != s) {
                        DBG("  - trying merge...\n");
                        /* We cannot merge if:
                         * - allocated dma_addr isn't contiguous to previous allocation
                         */
                        if (novmerge || (dma_addr != dma_next) ||
                            (outs->dma_length + s->length > max_seg_size)) {
                                /* Can't merge: create a new segment */
                                segstart = s;
                                outcount++;
                                outs = sg_next(outs);
                                DBG("    can't merge, new segment.\n");
                        } else {
                                outs->dma_length += s->length;
                                DBG("    merged, new len: %ux\n", outs->dma_length);
                        }
                }

                if (segstart == s) {
                        /* This is a new segment, fill entries */
                        DBG("  - filling new segment.\n");
                        outs->dma_address = dma_addr;
                        outs->dma_length = slen;
                }

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

                DBG("  - dma next is: %lx\n", dma_next);
        }

        /* Flush/invalidate TLB caches if necessary */
        if (ppc_md.tce_flush)
                ppc_md.tce_flush(tbl);

        spin_unlock_irqrestore(&(tbl->it_lock), flags);

        DBG("mapped %d elements:\n", outcount);

        /* For the sake of iommu_unmap_sg, we clear out the length in the
         * next entry of the sglist if we didn't fill the list completely
         */
        if (outcount < incount) {
                outs = sg_next(outs);
                outs->dma_address = DMA_ERROR_CODE;
                outs->dma_length = 0;
        }

        /* Make sure updates are seen by hardware */
        mb();

        return outcount;

 failure:
        for_each_sg(sglist, s, nelems, i) {
                if (s->dma_length != 0) {
                        unsigned long vaddr, npages;

                        vaddr = s->dma_address & IOMMU_PAGE_MASK;
                        npages = iommu_num_pages(s->dma_address, s->dma_length);
                        __iommu_free(tbl, vaddr, npages);
                        s->dma_address = DMA_ERROR_CODE;
                        s->dma_length = 0;
                }
                if (s == outs)
                        break;
        }
        spin_unlock_irqrestore(&(tbl->it_lock), flags);
        return 0;
}


void iommu_unmap_sg(struct iommu_table *tbl, struct scatterlist *sglist,
                int nelems, enum dma_data_direction direction)
{
        struct scatterlist *sg;
        unsigned long flags;

        BUG_ON(direction == DMA_NONE);

        if (!tbl)
                return;

        spin_lock_irqsave(&(tbl->it_lock), flags);

        sg = sglist;
        while (nelems--) {
                unsigned int npages;
                dma_addr_t dma_handle = sg->dma_address;

                if (sg->dma_length == 0)
                        break;
                npages = iommu_num_pages(dma_handle, sg->dma_length);
                __iommu_free(tbl, dma_handle, npages);
                sg = sg_next(sg);
        }

        /* Flush/invalidate TLBs if necessary. As for iommu_free(), we
         * do not do an mb() here, the affected platforms do not need it
         * when freeing.
         */
        if (ppc_md.tce_flush)
                ppc_md.tce_flush(tbl);

        spin_unlock_irqrestore(&(tbl->it_lock), flags);
}

/*
 * Build a iommu_table structure.  This contains a bit map which
 * is used to manage allocation of the tce space.
 */
struct iommu_table *iommu_init_table(struct iommu_table *tbl, int nid)
{
        unsigned long sz;
        static int welcomed = 0;
        struct page *page;

        /* Set aside 1/4 of the table for large allocations. */
        tbl->it_halfpoint = tbl->it_size * 3 / 4;

        /* number of bytes needed for the bitmap */
        sz = (tbl->it_size + 7) >> 3;

        page = alloc_pages_node(nid, GFP_ATOMIC, get_order(sz));
        if (!page)
                panic("iommu_init_table: Can't allocate %ld bytes\n", sz);
        tbl->it_map = page_address(page);
        memset(tbl->it_map, 0, sz);

        tbl->it_hint = 0;
        tbl->it_largehint = tbl->it_halfpoint;
        spin_lock_init(&tbl->it_lock);

#ifdef CONFIG_CRASH_DUMP
        if (ppc_md.tce_get) {
                unsigned long index;
                unsigned long tceval;
                unsigned long tcecount = 0;

                /*
                 * Reserve the existing mappings left by the first kernel.
                 */
                for (index = 0; index < tbl->it_size; index++) {
                        tceval = ppc_md.tce_get(tbl, index + tbl->it_offset);
                        /*
                         * Freed TCE entry contains 0x7fffffffffffffff on JS20
                         */
                        if (tceval && (tceval != 0x7fffffffffffffffUL)) {
                                __set_bit(index, tbl->it_map);
                                tcecount++;
                        }
                }
                if ((tbl->it_size - tcecount) < KDUMP_MIN_TCE_ENTRIES) {
                        printk(KERN_WARNING "TCE table is full; ");
                        printk(KERN_WARNING "freeing %d entries for the kdump boot\n",
                                KDUMP_MIN_TCE_ENTRIES);
                        for (index = tbl->it_size - KDUMP_MIN_TCE_ENTRIES;
                                index < tbl->it_size; index++)
                                __clear_bit(index, tbl->it_map);
                }
        }
#else
        /* Clear the hardware table in case firmware left allocations in it */
        ppc_md.tce_free(tbl, tbl->it_offset, tbl->it_size);
#endif

        if (!welcomed) {
                printk(KERN_INFO "IOMMU table initialized, virtual merging %s\n",
                       novmerge ? "disabled" : "enabled");
                welcomed = 1;
        }

        return tbl;
}

void iommu_free_table(struct iommu_table *tbl, const char *node_name)
{
        unsigned long bitmap_sz, i;
        unsigned int order;

        if (!tbl || !tbl->it_map) {
                printk(KERN_ERR "%s: expected TCE map for %s\n", __func__,
                                node_name);
                return;
        }

        /* verify that table contains no entries */
        /* it_size is in entries, and we're examining 64 at a time */
        for (i = 0; i < (tbl->it_size/64); i++) {
                if (tbl->it_map[i] != 0) {
                        printk(KERN_WARNING "%s: Unexpected TCEs for %s\n",
                                __func__, node_name);
                        break;
                }
        }

        /* calculate bitmap size in bytes */
        bitmap_sz = (tbl->it_size + 7) / 8;

        /* free bitmap */
        order = get_order(bitmap_sz);
        free_pages((unsigned long) tbl->it_map, order);

        /* free table */
        kfree(tbl);
}

/* Creates TCEs for a user provided buffer.  The user buffer must be
 * contiguous real kernel storage (not vmalloc).  The address of the buffer
 * passed here is the kernel (virtual) address of the buffer.  The buffer
 * need not be page aligned, the dma_addr_t returned will point to the same
 * byte within the page as vaddr.
 */
dma_addr_t iommu_map_single(struct device *dev, struct iommu_table *tbl,
                            void *vaddr, size_t size, unsigned long mask,
                            enum dma_data_direction direction)
{
        dma_addr_t dma_handle = DMA_ERROR_CODE;
        unsigned long uaddr;
        unsigned int npages, align;

        BUG_ON(direction == DMA_NONE);

        uaddr = (unsigned long)vaddr;
        npages = iommu_num_pages(uaddr, size);

        if (tbl) {
                align = 0;
                if (IOMMU_PAGE_SHIFT < PAGE_SHIFT && size >= PAGE_SIZE &&
                    ((unsigned long)vaddr & ~PAGE_MASK) == 0)
                        align = PAGE_SHIFT - IOMMU_PAGE_SHIFT;

                dma_handle = iommu_alloc(dev, tbl, vaddr, npages, direction,
                                         mask >> IOMMU_PAGE_SHIFT, align);
                if (dma_handle == DMA_ERROR_CODE) {
                        if (printk_ratelimit())  {
                                printk(KERN_INFO "iommu_alloc failed, "
                                                "tbl %p vaddr %p npages %d\n",
                                                tbl, vaddr, npages);
                        }
                } else
                        dma_handle |= (uaddr & ~IOMMU_PAGE_MASK);
        }

        return dma_handle;
}

void iommu_unmap_single(struct iommu_table *tbl, dma_addr_t dma_handle,
                size_t size, enum dma_data_direction direction)
{
        unsigned int npages;

        BUG_ON(direction == DMA_NONE);

        if (tbl) {
                npages = iommu_num_pages(dma_handle, size);
                iommu_free(tbl, dma_handle, npages);
        }
}

/* Allocates a contiguous real buffer and creates mappings over it.
 * Returns the virtual address of the buffer and sets dma_handle
 * to the dma address (mapping) of the first page.
 */
void *iommu_alloc_coherent(struct device *dev, struct iommu_table *tbl,
                           size_t size, dma_addr_t *dma_handle,
                           unsigned long mask, gfp_t flag, int node)
{
        void *ret = NULL;
        dma_addr_t mapping;
        unsigned int order;
        unsigned int nio_pages, io_order;
        struct page *page;

        size = PAGE_ALIGN(size);
        order = get_order(size);

        /*
         * Client asked for way too much space.  This is checked later
         * anyway.  It is easier to debug here for the drivers than in
         * the tce tables.
         */
        if (order >= IOMAP_MAX_ORDER) {
                printk("iommu_alloc_consistent size too large: 0x%lx\n", size);
                return NULL;
        }

        if (!tbl)
                return NULL;

        /* Alloc enough pages (and possibly more) */
        page = alloc_pages_node(node, flag, order);
        if (!page)
                return NULL;
        ret = page_address(page);
        memset(ret, 0, size);

        /* Set up tces to cover the allocated range */
        nio_pages = size >> IOMMU_PAGE_SHIFT;
        io_order = get_iommu_order(size);
        mapping = iommu_alloc(dev, tbl, ret, nio_pages, DMA_BIDIRECTIONAL,
                              mask >> IOMMU_PAGE_SHIFT, io_order);
        if (mapping == DMA_ERROR_CODE) {
                free_pages((unsigned long)ret, order);
                return NULL;
        }
        *dma_handle = mapping;
        return ret;
}

void iommu_free_coherent(struct iommu_table *tbl, size_t size,
                         void *vaddr, dma_addr_t dma_handle)
{
        if (tbl) {
                unsigned int nio_pages;

                size = PAGE_ALIGN(size);
                nio_pages = size >> IOMMU_PAGE_SHIFT;
                iommu_free(tbl, dma_handle, nio_pages);
                size = PAGE_ALIGN(size);
                free_pages((unsigned long)vaddr, get_order(size));
        }
}