drivers/gpu/drm/ttm/ttm_bo_vm.c - linux - Git at Google

 /**************************************************************************
  *
  * 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>
  */

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

 #define TTM_BO_VM_NUM_PREFAULT 16

 static struct ttm_buffer_object *ttm_bo_vm_lookup_rb(struct ttm_bo_device *bdev,
 						     unsigned long page_start,
 						     unsigned long num_pages)
 {
 	struct rb_node *cur = bdev->addr_space_rb.rb_node;
 	unsigned long cur_offset;
 	struct ttm_buffer_object *bo;
 	struct ttm_buffer_object *best_bo = NULL;

 	while (likely(cur != NULL)) {
 		bo = rb_entry(cur, struct ttm_buffer_object, vm_rb);
 		cur_offset = bo->vm_node->start;
 		if (page_start >= cur_offset) {
 			cur = cur->rb_right;
 			best_bo = bo;
 			if (page_start == cur_offset)
 				break;
 		} else
 			cur = cur->rb_left;
 	}

 	if (unlikely(best_bo == NULL))
 		return NULL;

 	if (unlikely((best_bo->vm_node->start + best_bo->num_pages) <
 		     (page_start + num_pages)))
 		return NULL;

 	return best_bo;
 }

 static int ttm_bo_vm_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
 {
 	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 ret;
 	int i;
 	unsigned long address = (unsigned long)vmf->virtual_address;
 	int retval = VM_FAULT_NOPAGE;
 	struct ttm_mem_type_manager *man =
 		&bdev->man[bo->mem.mem_type];

 	/*
 	 * 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 scheduling.
 	 */

 	ret = ttm_bo_reserve(bo, true, true, false, 0);
 	if (unlikely(ret != 0)) {
 		if (ret == -EBUSY)
 			set_need_resched();
 		return VM_FAULT_NOPAGE;
 	}

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

 	/*
 	 * Wait for buffer data in transit, due to a pipelined
 	 * move.
 	 */

 	spin_lock(&bdev->fence_lock);
 	if (test_bit(TTM_BO_PRIV_FLAG_MOVING, &bo->priv_flags)) {
 		ret = ttm_bo_wait(bo, false, true, false);
 		spin_unlock(&bdev->fence_lock);
 		if (unlikely(ret != 0)) {
 			retval = (ret != -ERESTARTSYS) ?
 			    VM_FAULT_SIGBUS : VM_FAULT_NOPAGE;
 			goto out_unlock;
 		}
 	} else
 		spin_unlock(&bdev->fence_lock);

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

 	page_offset = ((address - vma->vm_start) >> PAGE_SHIFT) +
 	    bo->vm_node->start - vma->vm_pgoff;
 	page_last = ((vma->vm_end - vma->vm_start) >> PAGE_SHIFT) +
 	    bo->vm_node->start - vma->vm_pgoff;

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

 	/*
 	 * 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.
 	 */
 	if (bo->mem.bus.is_iomem) {
 		vma->vm_page_prot = ttm_io_prot(bo->mem.placement,
 						vma->vm_page_prot);
 	} else {
 		ttm = bo->ttm;
 		vma->vm_page_prot = (bo->mem.placement & TTM_PL_FLAG_CACHED) ?
 		    vm_get_page_prot(vma->vm_flags) :
 		    ttm_io_prot(bo->mem.placement, vma->vm_page_prot);

 		/* Allocate all page at once, most common usage */
 		if (ttm->bdev->driver->ttm_tt_populate(ttm)) {
 			retval = 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)
 			pfn = ((bo->mem.bus.base + bo->mem.bus.offset) >> PAGE_SHIFT) + page_offset;
 		else {
 			page = ttm->pages[page_offset];
 			if (unlikely(!page && i == 0)) {
 				retval = VM_FAULT_OOM;
 				goto out_io_unlock;
 			} else if (unlikely(!page)) {
 				break;
 			}
 			pfn = page_to_pfn(page);
 		}

 		ret = vm_insert_mixed(vma, address, pfn);
 		/*
 		 * Somebody beat us to this PTE or prefaulting to
 		 * an already populated PTE, or prefaulting error.
 		 */

 		if (unlikely((ret == -EBUSY) || (ret != 0 && i > 0)))
 			break;
 		else if (unlikely(ret != 0)) {
 			retval =
 			    (ret == -ENOMEM) ? VM_FAULT_OOM : VM_FAULT_SIGBUS;
 			goto out_io_unlock;
 		}

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

 static void ttm_bo_vm_open(struct vm_area_struct *vma)
 {
 	struct ttm_buffer_object *bo =
 	    (struct ttm_buffer_object *)vma->vm_private_data;

 	(void)ttm_bo_reference(bo);
 }

 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_unref(&bo);
 	vma->vm_private_data = NULL;
 }

 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
 };

 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;

 	read_lock(&bdev->vm_lock);
 	bo = ttm_bo_vm_lookup_rb(bdev, vma->vm_pgoff,
 				 (vma->vm_end - vma->vm_start) >> PAGE_SHIFT);
 	if (likely(bo != NULL))
 		ttm_bo_reference(bo);
 	read_unlock(&bdev->vm_lock);

 	if (unlikely(bo == NULL)) {
 		printk(KERN_ERR TTM_PFX
 		       "Could not find buffer object to map.\n");
 		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;
 	vma->vm_flags |= VM_RESERVED | VM_IO | VM_MIXEDMAP | VM_DONTEXPAND;
 	return 0;
 out_unref:
 	ttm_bo_unref(&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;

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


 ssize_t ttm_bo_io(struct ttm_bo_device *bdev, struct file *filp,
 		  const char __user *wbuf, char __user *rbuf, size_t count,
 		  loff_t *f_pos, bool write)
 {
 	struct ttm_buffer_object *bo;
 	struct ttm_bo_driver *driver;
 	struct ttm_bo_kmap_obj map;
 	unsigned long dev_offset = (*f_pos >> PAGE_SHIFT);
 	unsigned long kmap_offset;
 	unsigned long kmap_end;
 	unsigned long kmap_num;
 	size_t io_size;
 	unsigned int page_offset;
 	char *virtual;
 	int ret;
 	bool no_wait = false;
 	bool dummy;

 	read_lock(&bdev->vm_lock);
 	bo = ttm_bo_vm_lookup_rb(bdev, dev_offset, 1);
 	if (likely(bo != NULL))
 		ttm_bo_reference(bo);
 	read_unlock(&bdev->vm_lock);

 	if (unlikely(bo == NULL))
 		return -EFAULT;

 	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;

 	kmap_offset = dev_offset - bo->vm_node->start;
 	if (unlikely(kmap_offset >= bo->num_pages)) {
 		ret = -EFBIG;
 		goto out_unref;
 	}

 	page_offset = *f_pos & ~PAGE_MASK;
 	io_size = bo->num_pages - kmap_offset;
 	io_size = (io_size << PAGE_SHIFT) - page_offset;
 	if (count < io_size)
 		io_size = count;

 	kmap_end = (*f_pos + count - 1) >> PAGE_SHIFT;
 	kmap_num = kmap_end - kmap_offset + 1;

 	ret = ttm_bo_reserve(bo, true, no_wait, false, 0);

 	switch (ret) {
 	case 0:
 		break;
 	case -EBUSY:
 		ret = -EAGAIN;
 		goto out_unref;
 	default:
 		goto out_unref;
 	}

 	ret = ttm_bo_kmap(bo, kmap_offset, kmap_num, &map);
 	if (unlikely(ret != 0)) {
 		ttm_bo_unreserve(bo);
 		goto out_unref;
 	}

 	virtual = ttm_kmap_obj_virtual(&map, &dummy);
 	virtual += page_offset;

 	if (write)
 		ret = copy_from_user(virtual, wbuf, io_size);
 	else
 		ret = copy_to_user(rbuf, virtual, io_size);

 	ttm_bo_kunmap(&map);
 	ttm_bo_unreserve(bo);
 	ttm_bo_unref(&bo);

 	if (unlikely(ret != 0))
 		return -EFBIG;

 	*f_pos += io_size;

 	return io_size;
 out_unref:
 	ttm_bo_unref(&bo);
 	return ret;
 }

 ssize_t ttm_bo_fbdev_io(struct ttm_buffer_object *bo, const char __user *wbuf,
 			char __user *rbuf, size_t count, loff_t *f_pos,
 			bool write)
 {
 	struct ttm_bo_kmap_obj map;
 	unsigned long kmap_offset;
 	unsigned long kmap_end;
 	unsigned long kmap_num;
 	size_t io_size;
 	unsigned int page_offset;
 	char *virtual;
 	int ret;
 	bool no_wait = false;
 	bool dummy;

 	kmap_offset = (*f_pos >> PAGE_SHIFT);
 	if (unlikely(kmap_offset >= bo->num_pages))
 		return -EFBIG;

 	page_offset = *f_pos & ~PAGE_MASK;
 	io_size = bo->num_pages - kmap_offset;
 	io_size = (io_size << PAGE_SHIFT) - page_offset;
 	if (count < io_size)
 		io_size = count;

 	kmap_end = (*f_pos + count - 1) >> PAGE_SHIFT;
 	kmap_num = kmap_end - kmap_offset + 1;

 	ret = ttm_bo_reserve(bo, true, no_wait, false, 0);

 	switch (ret) {
 	case 0:
 		break;
 	case -EBUSY:
 		return -EAGAIN;
 	default:
 		return ret;
 	}

 	ret = ttm_bo_kmap(bo, kmap_offset, kmap_num, &map);
 	if (unlikely(ret != 0)) {
 		ttm_bo_unreserve(bo);
 		return ret;
 	}

 	virtual = ttm_kmap_obj_virtual(&map, &dummy);
 	virtual += page_offset;

 	if (write)
 		ret = copy_from_user(virtual, wbuf, io_size);
 	else
 		ret = copy_to_user(rbuf, virtual, io_size);

 	ttm_bo_kunmap(&map);
 	ttm_bo_unreserve(bo);
 	ttm_bo_unref(&bo);

 	if (unlikely(ret != 0))
 		return ret;

 	*f_pos += io_size;

 	return io_size;
 }
	/**************************************************************************
	*
	* 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>
	*/

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

	#define TTM_BO_VM_NUM_PREFAULT 16

	static struct ttm_buffer_object ttm_bo_vm_lookup_rb(struct ttm_bo_device bdev,
	unsigned long page_start,
	unsigned long num_pages)
	{
	struct rb_node *cur = bdev->addr_space_rb.rb_node;
	unsigned long cur_offset;
	struct ttm_buffer_object *bo;
	struct ttm_buffer_object *best_bo = NULL;

	while (likely(cur != NULL)) {
	bo = rb_entry(cur, struct ttm_buffer_object, vm_rb);
	cur_offset = bo->vm_node->start;
	if (page_start >= cur_offset) {
	cur = cur->rb_right;
	best_bo = bo;
	if (page_start == cur_offset)
	break;
	} else
	cur = cur->rb_left;
	}

	if (unlikely(best_bo == NULL))
	return NULL;

	if (unlikely((best_bo->vm_node->start + best_bo->num_pages) <
	(page_start + num_pages)))
	return NULL;

	return best_bo;
	}

	static int ttm_bo_vm_fault(struct vm_area_struct vma, struct vm_fault vmf)
	{
	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 ret;
	int i;
	unsigned long address = (unsigned long)vmf->virtual_address;
	int retval = VM_FAULT_NOPAGE;
	struct ttm_mem_type_manager *man =
	&bdev->man[bo->mem.mem_type];

	/*
	* 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 scheduling.
	*/

	ret = ttm_bo_reserve(bo, true, true, false, 0);
	if (unlikely(ret != 0)) {
	if (ret == -EBUSY)
	set_need_resched();
	return VM_FAULT_NOPAGE;
	}

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

	/*
	* Wait for buffer data in transit, due to a pipelined
	* move.
	*/

	spin_lock(&bdev->fence_lock);
	if (test_bit(TTM_BO_PRIV_FLAG_MOVING, &bo->priv_flags)) {
	ret = ttm_bo_wait(bo, false, true, false);
	spin_unlock(&bdev->fence_lock);
	if (unlikely(ret != 0)) {
	retval = (ret != -ERESTARTSYS) ?
	VM_FAULT_SIGBUS : VM_FAULT_NOPAGE;
	goto out_unlock;
	}
	} else
	spin_unlock(&bdev->fence_lock);

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

	page_offset = ((address - vma->vm_start) >> PAGE_SHIFT) +
	bo->vm_node->start - vma->vm_pgoff;
	page_last = ((vma->vm_end - vma->vm_start) >> PAGE_SHIFT) +
	bo->vm_node->start - vma->vm_pgoff;

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

	/*
	* 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.
	*/
	if (bo->mem.bus.is_iomem) {
	vma->vm_page_prot = ttm_io_prot(bo->mem.placement,
	vma->vm_page_prot);
	} else {
	ttm = bo->ttm;
	vma->vm_page_prot = (bo->mem.placement & TTM_PL_FLAG_CACHED) ?
	vm_get_page_prot(vma->vm_flags) :
	ttm_io_prot(bo->mem.placement, vma->vm_page_prot);

	/* Allocate all page at once, most common usage */
	if (ttm->bdev->driver->ttm_tt_populate(ttm)) {
	retval = 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)
	pfn = ((bo->mem.bus.base + bo->mem.bus.offset) >> PAGE_SHIFT) + page_offset;
	else {
	page = ttm->pages[page_offset];
	if (unlikely(!page && i == 0)) {
	retval = VM_FAULT_OOM;
	goto out_io_unlock;
	} else if (unlikely(!page)) {
	break;
	}
	pfn = page_to_pfn(page);
	}

	ret = vm_insert_mixed(vma, address, pfn);
	/*
	* Somebody beat us to this PTE or prefaulting to
	* an already populated PTE, or prefaulting error.
	*/

	if (unlikely((ret == -EBUSY) \|\| (ret != 0 && i > 0)))
	break;
	else if (unlikely(ret != 0)) {
	retval =
	(ret == -ENOMEM) ? VM_FAULT_OOM : VM_FAULT_SIGBUS;
	goto out_io_unlock;
	}

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

	static void ttm_bo_vm_open(struct vm_area_struct *vma)
	{
	struct ttm_buffer_object *bo =
	(struct ttm_buffer_object *)vma->vm_private_data;

	(void)ttm_bo_reference(bo);
	}

	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_unref(&bo);
	vma->vm_private_data = NULL;
	}

	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
	};

	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;

	read_lock(&bdev->vm_lock);
	bo = ttm_bo_vm_lookup_rb(bdev, vma->vm_pgoff,
	(vma->vm_end - vma->vm_start) >> PAGE_SHIFT);
	if (likely(bo != NULL))
	ttm_bo_reference(bo);
	read_unlock(&bdev->vm_lock);

	if (unlikely(bo == NULL)) {
	printk(KERN_ERR TTM_PFX
	"Could not find buffer object to map.\n");
	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;
	vma->vm_flags \|= VM_RESERVED \| VM_IO \| VM_MIXEDMAP \| VM_DONTEXPAND;
	return 0;
	out_unref:
	ttm_bo_unref(&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;

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


	ssize_t ttm_bo_io(struct ttm_bo_device bdev, struct file filp,
	const char __user wbuf, char __user rbuf, size_t count,
	loff_t *f_pos, bool write)
	{
	struct ttm_buffer_object *bo;
	struct ttm_bo_driver *driver;
	struct ttm_bo_kmap_obj map;
	unsigned long dev_offset = (*f_pos >> PAGE_SHIFT);
	unsigned long kmap_offset;
	unsigned long kmap_end;
	unsigned long kmap_num;
	size_t io_size;
	unsigned int page_offset;
	char *virtual;
	int ret;
	bool no_wait = false;
	bool dummy;

	read_lock(&bdev->vm_lock);
	bo = ttm_bo_vm_lookup_rb(bdev, dev_offset, 1);
	if (likely(bo != NULL))
	ttm_bo_reference(bo);
	read_unlock(&bdev->vm_lock);

	if (unlikely(bo == NULL))
	return -EFAULT;

	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;

	kmap_offset = dev_offset - bo->vm_node->start;
	if (unlikely(kmap_offset >= bo->num_pages)) {
	ret = -EFBIG;
	goto out_unref;
	}

	page_offset = *f_pos & ~PAGE_MASK;
	io_size = bo->num_pages - kmap_offset;
	io_size = (io_size << PAGE_SHIFT) - page_offset;
	if (count < io_size)
	io_size = count;

	kmap_end = (*f_pos + count - 1) >> PAGE_SHIFT;
	kmap_num = kmap_end - kmap_offset + 1;

	ret = ttm_bo_reserve(bo, true, no_wait, false, 0);

	switch (ret) {
	case 0:
	break;
	case -EBUSY:
	ret = -EAGAIN;
	goto out_unref;
	default:
	goto out_unref;
	}

	ret = ttm_bo_kmap(bo, kmap_offset, kmap_num, &map);
	if (unlikely(ret != 0)) {
	ttm_bo_unreserve(bo);
	goto out_unref;
	}

	virtual = ttm_kmap_obj_virtual(&map, &dummy);
	virtual += page_offset;

	if (write)
	ret = copy_from_user(virtual, wbuf, io_size);
	else
	ret = copy_to_user(rbuf, virtual, io_size);

	ttm_bo_kunmap(&map);
	ttm_bo_unreserve(bo);
	ttm_bo_unref(&bo);

	if (unlikely(ret != 0))
	return -EFBIG;

	*f_pos += io_size;

	return io_size;
	out_unref:
	ttm_bo_unref(&bo);
	return ret;
	}

	ssize_t ttm_bo_fbdev_io(struct ttm_buffer_object bo, const char __user wbuf,
	char __user rbuf, size_t count, loff_t f_pos,
	bool write)
	{
	struct ttm_bo_kmap_obj map;
	unsigned long kmap_offset;
	unsigned long kmap_end;
	unsigned long kmap_num;
	size_t io_size;
	unsigned int page_offset;
	char *virtual;
	int ret;
	bool no_wait = false;
	bool dummy;

	kmap_offset = (*f_pos >> PAGE_SHIFT);
	if (unlikely(kmap_offset >= bo->num_pages))
	return -EFBIG;

	page_offset = *f_pos & ~PAGE_MASK;
	io_size = bo->num_pages - kmap_offset;
	io_size = (io_size << PAGE_SHIFT) - page_offset;
	if (count < io_size)
	io_size = count;

	kmap_end = (*f_pos + count - 1) >> PAGE_SHIFT;
	kmap_num = kmap_end - kmap_offset + 1;

	ret = ttm_bo_reserve(bo, true, no_wait, false, 0);

	switch (ret) {
	case 0:
	break;
	case -EBUSY:
	return -EAGAIN;
	default:
	return ret;
	}

	ret = ttm_bo_kmap(bo, kmap_offset, kmap_num, &map);
	if (unlikely(ret != 0)) {
	ttm_bo_unreserve(bo);
	return ret;
	}

	virtual = ttm_kmap_obj_virtual(&map, &dummy);
	virtual += page_offset;

	if (write)
	ret = copy_from_user(virtual, wbuf, io_size);
	else
	ret = copy_to_user(rbuf, virtual, io_size);

	ttm_bo_kunmap(&map);
	ttm_bo_unreserve(bo);
	ttm_bo_unref(&bo);

	if (unlikely(ret != 0))
	return ret;

	*f_pos += io_size;

	return io_size;
	}