/**************************************************************************
 *
 * Copyright (c) 2006-2009 VMware, Inc., Palo Alto, CA., USA
 * All Rights Reserved.
 *
 * Permission is hereby granted, free of charge, to any person obtaining a
 * copy of this software and associated documentation files (the
 * "Software"), to deal in the Software without restriction, including
 * without limitation the rights to use, copy, modify, merge, publish,
 * distribute, sub license, and/or sell copies of the Software, and to
 * permit persons to whom the Software is furnished to do so, subject to
 * the following conditions:
 *
 * The above copyright notice and this permission notice (including the
 * next paragraph) shall be included in all copies or substantial portions
 * of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT. IN NO EVENT SHALL
 * THE COPYRIGHT HOLDERS, AUTHORS AND/OR ITS SUPPLIERS BE LIABLE FOR ANY CLAIM,
 * DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR
 * OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE
 * USE OR OTHER DEALINGS IN THE SOFTWARE.
 *
 **************************************************************************/
/*
 * Authors: Thomas Hellstrom <thellstrom-at-vmware-dot-com>
 */

#define pr_fmt(fmt) "[TTM] " fmt

#include <drm/ttm/ttm_module.h>
#include <drm/ttm/ttm_bo_driver.h>
#include <drm/ttm/ttm_placement.h>
#include <drm/drm_vma_manager.h>
#include <linux/mm.h>
#include <linux/pfn_t.h>
#include <linux/rbtree.h>
#include <linux/module.h>
#include <linux/uaccess.h>
#include <linux/mem_encrypt.h>

#include <sys/sysctl.h>
#include <vm/vm.h>
#include <vm/vm_page.h>
#include <vm/vm_page2.h>

#define TTM_BO_VM_NUM_PREFAULT 16

static int ttm_bo_vm_fault_idle(struct ttm_buffer_object *bo,
                                struct vm_fault *vmf)
{
        int ret = 0;

        if (likely(!bo->moving))
                goto out_unlock;

        /*
         * Quick non-stalling check for idle.
         */
        if (dma_fence_is_signaled(bo->moving))
                goto out_clear;

        /*
         * If possible, avoid waiting for GPU with mmap_sem
         * held.
         */
        if (vmf->flags & FAULT_FLAG_ALLOW_RETRY) {
                ret = VM_FAULT_RETRY;
                if (vmf->flags & FAULT_FLAG_RETRY_NOWAIT)
                        goto out_unlock;

                ttm_bo_get(bo);
                up_read(&vmf->vma->vm_mm->mmap_sem);            /* release */
                (void) dma_fence_wait(bo->moving, true);
                ttm_bo_unreserve(bo);
                ttm_bo_put(bo);
                down_read(&vmf->vma->vm_mm->mmap_sem);          /* acquire */
                goto out_unlock;
        }

        /*
         * Ordinary wait.
         */
        ret = dma_fence_wait(bo->moving, true);
        if (unlikely(ret != 0)) {
                ret = (ret != -ERESTARTSYS) ? VM_FAULT_SIGBUS :
                        VM_FAULT_NOPAGE;
                goto out_unlock;
        }

out_clear:
        dma_fence_put(bo->moving);
        bo->moving = NULL;

out_unlock:
        return ret;
}

/*
 * Always unstall on unexpected vm_page alias, fatal bus fault.
 * Set to 0 to stall, set to positive count to unstall N times,
 * then stall again.
 */
static int drm_unstall = -1;
SYSCTL_INT(_debug, OID_AUTO, unstall, CTLFLAG_RW, &drm_unstall, 0, "");

static int ttm_bo_vm_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
{
        /* see ttm_bo_mmap_single() at end of this file */
        /* ttm_bo_vm_ops not currently used, no entry should occur */
        panic("ttm_bo_vm_fault");
#if 0
        struct ttm_buffer_object *bo = (struct ttm_buffer_object *)
            vma->vm_private_data;
        struct ttm_bo_device *bdev = bo->bdev;
        unsigned long page_offset;
        unsigned long page_last;
        unsigned long pfn;
        struct ttm_tt *ttm = NULL;
        struct page *page;
        int err;
        int i;
        vm_fault_t ret = VM_FAULT_NOPAGE;
        unsigned long address = vmf->address;
        struct ttm_mem_type_manager *man =
                &bdev->man[bo->mem.mem_type];
        struct vm_area_struct cvma;

        /*
         * Work around locking order reversal in fault / nopfn
         * between mmap_sem and bo_reserve: Perform a trylock operation
         * for reserve, and if it fails, retry the fault after waiting
         * for the buffer to become unreserved.
         */
        err = ttm_bo_reserve(bo, true, true, NULL);
        if (unlikely(err != 0)) {
                if (err != -EBUSY)
                        return VM_FAULT_NOPAGE;

                if (vmf->flags & FAULT_FLAG_ALLOW_RETRY) {
                        if (!(vmf->flags & FAULT_FLAG_RETRY_NOWAIT)) {
                                ttm_bo_get(bo);
                                up_read(&vmf->vma->vm_mm->mmap_sem);
                                (void) ttm_bo_wait_unreserved(bo);
                                ttm_bo_put(bo);
                        }

                        return VM_FAULT_RETRY;
                }

                /*
                 * If we'd want to change locking order to
                 * mmap_sem -> bo::reserve, we'd use a blocking reserve here
                 * instead of retrying the fault...
                 */
                return VM_FAULT_NOPAGE;
        }

        /*
         * Refuse to fault imported pages. This should be handled
         * (if at all) by redirecting mmap to the exporter.
         */
        if (bo->ttm && (bo->ttm->page_flags & TTM_PAGE_FLAG_SG)) {
                ret = VM_FAULT_SIGBUS;
                goto out_unlock;
        }

        if (bdev->driver->fault_reserve_notify) {
                err = bdev->driver->fault_reserve_notify(bo);
                switch (err) {
                case 0:
                        break;
                case -EBUSY:
                case -ERESTARTSYS:
                        ret = VM_FAULT_NOPAGE;
                        goto out_unlock;
                default:
                        ret = VM_FAULT_SIGBUS;
                        goto out_unlock;
                }
        }

        /*
         * Wait for buffer data in transit, due to a pipelined
         * move.
         */
        ret = ttm_bo_vm_fault_idle(bo, vmf);
        if (unlikely(ret != 0)) {
                if (ret == VM_FAULT_RETRY &&
                    !(vmf->flags & FAULT_FLAG_RETRY_NOWAIT)) {
                        /* The BO has already been unreserved. */
                        return ret;
                }

                goto out_unlock;
        }

        err = ttm_mem_io_lock(man, true);
        if (unlikely(err != 0)) {
                ret = VM_FAULT_NOPAGE;
                goto out_unlock;
        }
        err = ttm_mem_io_reserve_vm(bo);
        if (unlikely(err != 0)) {
                ret = VM_FAULT_SIGBUS;
                goto out_io_unlock;
        }

        page_offset = ((address - vma->vm_start) >> PAGE_SHIFT) +
                vma->vm_pgoff - drm_vma_node_start(&bo->vma_node);
        page_last = vma_pages(vma) + vma->vm_pgoff -
                drm_vma_node_start(&bo->vma_node);

        if (unlikely(page_offset >= bo->num_pages)) {
                ret = VM_FAULT_SIGBUS;
                goto out_io_unlock;
        }

        /*
         * Make a local vma copy to modify the page_prot member
         * and vm_flags if necessary. The vma parameter is protected
         * by mmap_sem in write mode.
         */
        cvma = *vma;
        cvma.vm_page_prot = vm_get_page_prot(cvma.vm_flags);

        if (bo->mem.bus.is_iomem) {
                cvma.vm_page_prot = ttm_io_prot(bo->mem.placement,
                                                cvma.vm_page_prot);
        } else {
                struct ttm_operation_ctx ctx = {
                        .interruptible = false,
                        .no_wait_gpu = false,
                        .flags = TTM_OPT_FLAG_FORCE_ALLOC

                };

                ttm = bo->ttm;
                cvma.vm_page_prot = ttm_io_prot(bo->mem.placement,
                                                cvma.vm_page_prot);

                /* Allocate all page at once, most common usage */
                if (ttm_tt_populate(ttm, &ctx)) {
                        ret = VM_FAULT_OOM;
                        goto out_io_unlock;
                }
        }

        /*
         * Speculatively prefault a number of pages. Only error on
         * first page.
         */
        for (i = 0; i < TTM_BO_VM_NUM_PREFAULT; ++i) {
                if (bo->mem.bus.is_iomem) {
                        /* Iomem should not be marked encrypted */
                        cvma.vm_page_prot = pgprot_decrypted(cvma.vm_page_prot);
                        pfn = ttm_bo_io_mem_pfn(bo, page_offset);
                } else {
                        page = ttm->pages[page_offset];
                        if (unlikely(!page && i == 0)) {
                                ret = VM_FAULT_OOM;
                                goto out_io_unlock;
                        } else if (unlikely(!page)) {
                                break;
                        }
                        page->index = drm_vma_node_start(&bo->vma_node) +
                                page_offset;
                        pfn = page_to_pfn(page);
                }

                if (vma->vm_flags & VM_MIXEDMAP)
                        ret = vmf_insert_mixed(&cvma, address,
                                        __pfn_to_pfn_t(pfn, PFN_DEV));
                else
                        ret = vmf_insert_pfn(&cvma, address, pfn);

                /*
                 * Somebody beat us to this PTE or prefaulting to
                 * an already populated PTE, or prefaulting error.
                 */

                if (unlikely((ret == VM_FAULT_NOPAGE && i > 0)))
                        break;
                else if (unlikely(ret & VM_FAULT_ERROR))
                        goto out_io_unlock;

                address += PAGE_SIZE;
                if (unlikely(++page_offset >= page_last))
                        break;
        }
        ret = VM_FAULT_NOPAGE;
out_io_unlock:
        ttm_mem_io_unlock(man);
out_unlock:
        ttm_bo_unreserve(bo);
        return ret;
#endif
}

/* ttm_bo_vm_ops not currently used, no entry should occur */
static void ttm_bo_vm_open(struct vm_area_struct *vma)
{
        struct ttm_buffer_object *bo =
            (struct ttm_buffer_object *)vma->vm_private_data;

#if 0
        WARN_ON(bo->bdev->dev_mapping != vma->vm_file->f_mapping);
#endif

        ttm_bo_get(bo);
}

/* ttm_bo_vm_ops not currently used, no entry should occur */
static void ttm_bo_vm_close(struct vm_area_struct *vma)
{
        struct ttm_buffer_object *bo = (struct ttm_buffer_object *)vma->vm_private_data;

        ttm_bo_put(bo);
        vma->vm_private_data = NULL;
}

static int ttm_bo_vm_access_kmap(struct ttm_buffer_object *bo,
                                 unsigned long offset,
                                 uint8_t *buf, int len, int write)
{
        unsigned long page = offset >> PAGE_SHIFT;
        unsigned long bytes_left = len;
        int ret;

        /* Copy a page at a time, that way no extra virtual address
         * mapping is needed
         */
        offset -= page << PAGE_SHIFT;
        do {
                unsigned long bytes = min(bytes_left, PAGE_SIZE - offset);
                struct ttm_bo_kmap_obj map;
                void *ptr;
                bool is_iomem;

                ret = ttm_bo_kmap(bo, page, 1, &map);
                if (ret)
                        return ret;

                ptr = (uint8_t *)ttm_kmap_obj_virtual(&map, &is_iomem) + offset;
                WARN_ON_ONCE(is_iomem);
                if (write)
                        memcpy(ptr, buf, bytes);
                else
                        memcpy(buf, ptr, bytes);
                ttm_bo_kunmap(&map);

                page++;
                buf += bytes;
                bytes_left -= bytes;
                offset = 0;
        } while (bytes_left);

        return len;
}

static int ttm_bo_vm_access(struct vm_area_struct *vma, unsigned long addr,
                            void *buf, int len, int write)
{
        unsigned long offset = (addr) - vma->vm_start;
        struct ttm_buffer_object *bo = vma->vm_private_data;
        int ret;

        if (len < 1 || (offset + len) >> PAGE_SHIFT > bo->num_pages)
                return -EIO;

        ret = ttm_bo_reserve(bo, true, false, NULL);
        if (ret)
                return ret;

        switch (bo->mem.mem_type) {
        case TTM_PL_SYSTEM:
                if (unlikely(bo->ttm->page_flags & TTM_PAGE_FLAG_SWAPPED)) {
                        ret = ttm_tt_swapin(bo->ttm);
                        if (unlikely(ret != 0))
                                return ret;
                }
                /* fall through */
        case TTM_PL_TT:
                ret = ttm_bo_vm_access_kmap(bo, offset, buf, len, write);
                break;
        default:
                if (bo->bdev->driver->access_memory)
                        ret = bo->bdev->driver->access_memory(
                                bo, offset, buf, len, write);
                else
                        ret = -EIO;
        }

        ttm_bo_unreserve(bo);

        return ret;
}

static const struct vm_operations_struct ttm_bo_vm_ops = {
        .fault = ttm_bo_vm_fault,
        .open = ttm_bo_vm_open,
        .close = ttm_bo_vm_close,
        .access = ttm_bo_vm_access
};

static struct ttm_buffer_object *ttm_bo_vm_lookup(struct ttm_bo_device *bdev,
                                                  unsigned long offset,
                                                  unsigned long pages)
{
        struct drm_vma_offset_node *node;
        struct ttm_buffer_object *bo = NULL;

        drm_vma_offset_lock_lookup(&bdev->vma_manager);

        node = drm_vma_offset_lookup_locked(&bdev->vma_manager, offset, pages);
        if (likely(node)) {
                bo = container_of(node, struct ttm_buffer_object, vma_node);
                bo = ttm_bo_get_unless_zero(bo);
        }

        drm_vma_offset_unlock_lookup(&bdev->vma_manager);

        if (!bo)
                pr_err("Could not find buffer object to map\n");

        return bo;
}

int ttm_bo_mmap(struct file *filp, struct vm_area_struct *vma,
                struct ttm_bo_device *bdev)
{
        struct ttm_bo_driver *driver;
        struct ttm_buffer_object *bo;
        int ret;

        bo = ttm_bo_vm_lookup(bdev, vma->vm_pgoff, vma_pages(vma));
        if (unlikely(!bo))
                return -EINVAL;

        driver = bo->bdev->driver;
        if (unlikely(!driver->verify_access)) {
                ret = -EPERM;
                goto out_unref;
        }
        ret = driver->verify_access(bo, filp);
        if (unlikely(ret != 0))
                goto out_unref;

        vma->vm_ops = &ttm_bo_vm_ops;

        /*
         * Note: We're transferring the bo reference to
         * vma->vm_private_data here.
         */

        vma->vm_private_data = bo;

        /*
         * We'd like to use VM_PFNMAP on shared mappings, where
         * (vma->vm_flags & VM_SHARED) != 0, for performance reasons,
         * but for some reason VM_PFNMAP + x86 PAT + write-combine is very
         * bad for performance. Until that has been sorted out, use
         * VM_MIXEDMAP on all mappings. See freedesktop.org bug #75719
         */
        vma->vm_flags |= VM_MIXEDMAP;
        vma->vm_flags |= VM_IO | VM_DONTEXPAND | VM_DONTDUMP;
        return 0;
out_unref:
        ttm_bo_put(bo);
        return ret;
}
EXPORT_SYMBOL(ttm_bo_mmap);

int ttm_fbdev_mmap(struct vm_area_struct *vma, struct ttm_buffer_object *bo)
{
        if (vma->vm_pgoff != 0)
                return -EACCES;

        ttm_bo_get(bo);

        vma->vm_ops = &ttm_bo_vm_ops;
        vma->vm_private_data = bo;
        vma->vm_flags |= VM_MIXEDMAP;
        vma->vm_flags |= VM_IO | VM_DONTEXPAND;
        return 0;
}
EXPORT_SYMBOL(ttm_fbdev_mmap);

/*
 * DragonFlyBSD Interface
 */

/*
 * NOTE: This code is fragile.  This code can only be entered with *mres
 *       not NULL when *mres is a placeholder page allocated by the kernel.
 */
static int
ttm_bo_vm_fault_dfly(vm_object_t vm_obj, vm_ooffset_t offset,
                     int prot, vm_page_t *mres)
{
        struct ttm_buffer_object *bo = vm_obj->handle;
        struct ttm_bo_device *bdev = bo->bdev;
        struct ttm_tt *ttm = NULL;
        vm_page_t m;
        int ret;
        int retval = VM_PAGER_OK;
        struct ttm_mem_type_manager *man =
                &bdev->man[bo->mem.mem_type];
        struct vm_area_struct cvma;

/*
   The Linux code expects to receive these arguments:
   - struct vm_area_struct *vma
   - struct vm_fault *vmf
*/
#ifdef __DragonFly__
        struct vm_area_struct vmas;
        struct vm_area_struct *vma = &vmas;
        struct vm_fault vmfs;
        struct vm_fault *vmf = &vmfs;

        memset(vma, 0, sizeof(*vma));
        memset(vmf, 0, sizeof(*vmf));

        vma->vm_mm = current->mm;
        vmf->vma = vma;

        int retry_count = 0;
#endif

        vm_object_pip_add(vm_obj, 1);

        /*
         * OBJT_MGTDEVICE does not pre-allocate the page.
         */
        KKASSERT(*mres == NULL);

retry:
        /* The Linux page fault handler acquires mmap_sem */
        down_read(&vma->vm_mm->mmap_sem);

        m = NULL;

        /*
         * Work around locking order reversal in fault / nopfn
         * between mmap_sem and bo_reserve: Perform a trylock operation
         * for reserve, and if it fails, retry the fault after waiting
         * for the buffer to become unreserved.
         */
        ret = ttm_bo_reserve(bo, true, true, NULL);
        if (unlikely(ret != 0)) {
                if (ret != -EBUSY) {
                        retval = VM_PAGER_ERROR;
                        goto out_unlock2;
                }

                if (vmf->flags & FAULT_FLAG_ALLOW_RETRY || 1) {
                        if (!(vmf->flags & FAULT_FLAG_RETRY_NOWAIT)) {
                                up_read(&vma->vm_mm->mmap_sem);
                                (void) ttm_bo_wait_unreserved(bo);
                                down_read(&vma->vm_mm->mmap_sem);
                        }

#ifndef __DragonFly__
                        return VM_FAULT_RETRY;
#else
                        up_read(&vma->vm_mm->mmap_sem);
                        lwkt_yield();
                        goto retry;
#endif
                }

                /*
                 * If we'd want to change locking order to
                 * mmap_sem -> bo::reserve, we'd use a blocking reserve here
                 * instead of retrying the fault...
                 */
                retval = VM_PAGER_ERROR;
                goto out_unlock2;
        }

        if (bdev->driver->fault_reserve_notify) {
                ret = bdev->driver->fault_reserve_notify(bo);
                switch (ret) {
                case 0:
                        break;
                case -EBUSY:
                        lwkt_yield();
                        /* fall through */
                case -ERESTARTSYS:
                case -EINTR:
                        retval = VM_PAGER_ERROR;
                        goto out_unlock1;
                default:
                        retval = VM_PAGER_ERROR;
                        goto out_unlock1;
                }
        }

        /*
         * Wait for buffer data in transit, due to a pipelined
         * move.
         */
        ret = ttm_bo_vm_fault_idle(bo, vmf);
        if (unlikely(ret != 0)) {
                if (retry_count >= 100) {
                        retval = VM_PAGER_ERROR;
                        goto out_unlock1;
                } else {
                        retry_count++;
                        ttm_bo_unreserve(bo);
                        up_read(&vma->vm_mm->mmap_sem);
                        int dummy;
                        tsleep(&dummy, 0, "blah", 1);

                        goto retry;
                }
        }

        ret = ttm_mem_io_lock(man, true);
        if (unlikely(ret != 0)) {
                retval = VM_PAGER_ERROR;
                goto out_unlock1;
        }
        ret = ttm_mem_io_reserve_vm(bo);
        if (unlikely(ret != 0)) {
                retval = VM_PAGER_ERROR;
                goto out_io_unlock1;
        }
        if (unlikely(OFF_TO_IDX(offset) >= bo->num_pages)) {
                retval = VM_PAGER_ERROR;
                goto out_io_unlock1;
        }

        /*
         * Lookup the real page.
         *
         * Strictly, we're not allowed to modify vma->vm_page_prot here,
         * since the mmap_sem is only held in read mode. However, we
         * modify only the caching bits of vma->vm_page_prot and
         * consider those bits protected by
         * the bo->mutex, as we should be the only writers.
         * There shouldn't really be any readers of these bits except
         * within vm_insert_mixed()? fork?
         *
         * TODO: Add a list of vmas to the bo, and change the
         * vma->vm_page_prot when the object changes caching policy, with
         * the correct locks held.
         */

        /*
         * Make a local vma copy to modify the page_prot member
         * and vm_flags if necessary. The vma parameter is protected
         * by mmap_sem in write mode.
         */
        cvma = *vma;
#if 0
        cvma.vm_page_prot = vm_get_page_prot(cvma.vm_flags);
#else
        cvma.vm_page_prot = 0;
#endif

        if (bo->mem.bus.is_iomem) {
#ifdef __DragonFly__
                m = vm_phys_fictitious_to_vm_page(bo->mem.bus.base +
                                                  bo->mem.bus.offset + offset);
                pmap_page_set_memattr(m, ttm_io_prot(bo->mem.placement, 0));
#endif
                cvma.vm_page_prot = ttm_io_prot(bo->mem.placement,
                                                cvma.vm_page_prot);
        } else {
                ttm = bo->ttm;
                cvma.vm_page_prot = ttm_io_prot(bo->mem.placement,
                                                cvma.vm_page_prot);

                /* Allocate all page at once, most common usage */
                struct ttm_operation_ctx ctx = {
                        .interruptible = false,
                        .no_wait_gpu = false,
                        .flags = TTM_OPT_FLAG_FORCE_ALLOC

                };
                if (ttm_tt_populate(ttm, &ctx)) {
                        retval = VM_PAGER_ERROR;
                        goto out_io_unlock1;
                }

                m = (struct vm_page *)ttm->pages[OFF_TO_IDX(offset)];
                if (unlikely(!m)) {
                        retval = VM_PAGER_ERROR;
                        goto out_io_unlock1;
                }
                pmap_page_set_memattr(m,
                    (bo->mem.placement & TTM_PL_FLAG_CACHED) ?
                    VM_MEMATTR_WRITE_BACK : ttm_io_prot(bo->mem.placement, 0));
        }

        if (vm_page_busy_try(m, FALSE)) {
                kprintf("r");
                vm_page_sleep_busy(m, FALSE, "ttmvmf");
                ttm_mem_io_unlock(man);
                ttm_bo_unreserve(bo);
                up_read(&vma->vm_mm->mmap_sem);
                goto retry;
        }

        /*
         * Return our fake page BUSYd.  Do not index it into the VM object.
         * The caller will enter it into the pmap.
         */
        m->valid = VM_PAGE_BITS_ALL;
        *mres = m;

out_io_unlock1:
        ttm_mem_io_unlock(man);
out_unlock1:
        ttm_bo_unreserve(bo);
out_unlock2:
        vm_object_pip_wakeup(vm_obj);
        up_read(&vma->vm_mm->mmap_sem);

        return (retval);
}

static int
ttm_bo_vm_ctor(void *handle, vm_ooffset_t size, vm_prot_t prot,
               vm_ooffset_t foff, struct ucred *cred, u_short *color)
{

        /*
         * On Linux, a reference to the buffer object is acquired here.
         * The reason is that this function is not called when the
         * mmap() is initialized, but only when a process forks for
         * instance. Therefore on Linux, the reference on the bo is
         * acquired either in ttm_bo_mmap() or ttm_bo_vm_open(). It's
         * then released in ttm_bo_vm_close().
         *
         * Here, this function is called during mmap() intialization.
         * Thus, the reference acquired in ttm_bo_mmap_single() is
         * sufficient.
         */
        *color = 0;
        return (0);
}

static void
ttm_bo_vm_dtor(void *handle)
{
        struct ttm_buffer_object *bo = handle;

        ttm_bo_unref(&bo);
}

static struct cdev_pager_ops ttm_pager_ops = {
        .cdev_pg_fault = ttm_bo_vm_fault_dfly,
        .cdev_pg_ctor = ttm_bo_vm_ctor,
        .cdev_pg_dtor = ttm_bo_vm_dtor
};

/*
 * Called from drm_drv.c
 *
 * *offset - object offset in bytes
 * size    - map size in bytes
 *
 * We setup a dummy vma (for now) and call ttm_bo_mmap().  Then we setup
 * our own VM object and dfly ops.  Note that the ops supplied by
 * ttm_bo_mmap() are not currently used.
 */
int
ttm_bo_mmap_single(struct file *fp, struct drm_device *dev,
                   vm_ooffset_t *offset, vm_size_t size,
                   struct vm_object **obj_res, int nprot)
{
        struct ttm_bo_device *bdev = dev->drm_ttm_bdev;
        struct ttm_buffer_object *bo;
        struct vm_object *vm_obj;
        struct vm_area_struct vma;
        int ret;

        *obj_res = NULL;

        bzero(&vma, sizeof(vma));
        vma.vm_start = *offset;         /* bdev-relative offset */
        vma.vm_end = vma.vm_start + size;
        vma.vm_pgoff = vma.vm_start >> PAGE_SHIFT;
        /* vma.vm_page_prot */
        /* vma.vm_flags */

        /*
         * Call the linux-ported code to do the work, and on success just
         * setup our own VM object and ignore what the linux code did other
         * then supplying us the 'bo'.
         */
        ret = ttm_bo_mmap(fp, &vma, bdev);

        if (ret == 0) {
                bo = vma.vm_private_data;
                vm_obj = cdev_pager_allocate(bo, OBJT_MGTDEVICE,
                                             &ttm_pager_ops,
                                             size, nprot, 0,
                                             curthread->td_ucred);
                if (vm_obj) {
                        *obj_res = vm_obj;
                        *offset = 0;            /* object-relative offset */
                } else {
                        ttm_bo_unref(&bo);
                        ret = EINVAL;
                }
        }
        return ret;
}
EXPORT_SYMBOL(ttm_bo_mmap_single);

#ifdef __DragonFly__
void ttm_bo_release_mmap(struct ttm_buffer_object *bo);

void
ttm_bo_release_mmap(struct ttm_buffer_object *bo)
{
        vm_object_t vm_obj;

        vm_obj = cdev_pager_lookup(bo);
        if (vm_obj == NULL)
                return;

        VM_OBJECT_LOCK(vm_obj);
#if 1
        vm_object_page_remove(vm_obj, 0, 0, false);
#else
        /*
         * XXX REMOVED
         *
         * We no longer manage the vm pages inside the MGTDEVICE
         * objects.
         */
        vm_page_t m;
        int i;

        for (i = 0; i < bo->num_pages; i++) {
                m = vm_page_lookup_busy_wait(vm_obj, i, TRUE, "ttm_unm");
                if (m == NULL)
                        continue;
                cdev_pager_free_page(vm_obj, m);
        }
#endif
        VM_OBJECT_UNLOCK(vm_obj);

        vm_object_deallocate(vm_obj);
}
#endif

#if 0
int ttm_fbdev_mmap(struct vm_area_struct *vma, struct ttm_buffer_object *bo)
{
        if (vma->vm_pgoff != 0)
                return -EACCES;

        vma->vm_ops = &ttm_bo_vm_ops;
        vma->vm_private_data = ttm_bo_reference(bo);
        vma->vm_flags |= VM_IO | VM_MIXEDMAP | VM_DONTEXPAND;
        return 0;
}
EXPORT_SYMBOL(ttm_fbdev_mmap);
#endif